A Framework Profile of .NET

Ralf Lammel, Rufus Linke, Ekaterina Pek, and Andrei VaranovichSoftware Languages Team & ADAPT Lab

Universitat Koblenz-Landau, Germany

Abstract—We develop a basic form of framework com-prehension which is based on simple, reuse-related metricsfor the as-implemented design and usage of frameworks. Tothis end, we provide a framework profile which incorporatespotential reuse characteristics (e.g., specializability of typesin a framework) as well as actual reuse characteristics (e.g.,evidence of specialization of framework types in projects). Weapply framework comprehension in an empirical study of theMicrosoft .NET Framework. The approach is helpful in severalcontexts of software reverse and re-engineering.

Keywords-framework, .NET, framework design, frameworkusage, framework profile, reuse, type specialization, late bind-ing, polymorphism, inheritance, program comprehension, soft-ware metrics, dynamic program analysis.

I. INTRODUCTION

Suppose you need to (better) understand the architectureof a platform such as the Java Standard Edition1, the Mi-crosoft .NET Framework2, or another composite framework.There is no silver bullet for such framework comprehension,but a range of models may be useful in this context. Thepresent paper describes the notion of framework profilewhich incorporates characteristics of potential and actualreuse of frameworks. The approach is applied to the Mi-crosoft .NET Framework and a corpus of .NET projects inan empirical study.

Framework comprehension supports reverse and re-engineering activities. In quality assessment of designs [1],framework profiles help understanding frameworks in amanner complementary to architectural smells, patterns, oranti-patterns. Also, one can compare given projects withthe framework profile. More specifically, in framework re-modularization, framework profiles help summarizing thestatus of modularization and motivating refactorings [2]. InAPI migration [3], framework profiles help assessing APIreplacement options with regard to, for example, differentextensibility characteristics. Finally, framework profiles helpin teaching OO architecture, design, and implementation [4].

A framework profile is illustrated in Figure 1. Reuse-related properties are depicted for a number of .NET name-spaces and open-source projects; the names are elided here.The infographics is derived from the results of static anddynamic program analysis. The leftmost column displaysa metric for the percentage of specializable types (i.e.,

1http://www.oracle.com/us/javase2http://www.microsoft.com/net/

• N N N ∗ ∗ �

• – – � – – – –• – – N – – – –• � N

• ∗ ∗ ∗ ∗ N N ∗• ∗ � N � � N ∗ � N N N � ∗ �

• ∗ � ∗ ∗ ∗ ∗ N ∗ ∗ � ∗ ∗• ∗ ∗ ∗ ∗ ∗ ∗• � � � � � N � � � � � � � � � N � �

• ∗ N ∗

Rows: top-10 .NET namespaces, in terms of number of types.Middle block of columns: actual reuse by project of the corpus.Leftmost column: potential reuse in terms of specializability.Rightmost column: summary of actual reuse.

Figure 1. Infographics for an excerpt of a framework profile for .NET

non-sealed, non-static classes and all interfaces) by usingbullets of increasing size. (This approach will be definedmore precisely later on.) The bulk of the columns classifyactual reuse of namespaces by projects as follows: ‘–’ – thenamespace was not available in the framework version usedby the project; ‘∗’ – the namespace is referenced; ‘N’ – thenamespace is even specialized by the project (i.e., there isa project type that extends or implements a type of thenamespace); ‘�’ – late binding involves the namespace (i.e.,there is a project type that acts as runtime receiver type fora call with a static receiver type from the namespace). Therightmost column summarizes actual reuse by means of thedominating classifier, if any, for each row.

Overall, the figure contrasts potential with actual reuse ata high-level of abstraction.

Summary of contributions3

• We use metrics to analyze potential and actual frameworkreuse for some limited forms of reuse. To this end, weleverage static and dynamic program analysis.• The metrics also help classifying composite frameworks

with regard to reuse so that namespaces can be associatedwith categories that describe reuse characteristics concisely.• We describe an empirical study for the Microsoft .NET

framework and a corpus of .NET projects such that reusecharacteristics add up to a framework profile for .NET.

Road-map§ II describes our methodology. § III explores reuse-related met-

rics for frameworks. § IV proposes a classification of frameworks.§V studies actual framework reuse. §VI identifies threats tovalidity. §VII discusses related work. §VIII concludes the paper.

3The paper’s web site, http://softlang.uni-koblenz.de/dotnet, providessupport material for the empirical study.

.NET Project Repository LOC Description

3.5 Castle ActiveRecord GitHub 30,303 Object-relational mapper4.0 Castle Core Library GitHub 36,659 Core library for the Castle framework3.5 Castle MonoRail GitHub 58,121 MVC Web framework4.0 Castle Windsor GitHub 50,032 Inversion of control container4.0 Json.NET Codeplex 43,127 JSON framework2.0 log4net Sourceforge 27,799 Logging framework2.0 Lucene.Net Apache.org 158,519 Search engine4.0 Managed Extensibility Framework Codeplex 149,303 Framework for extensible applications and components4.0 Moq GoogleCode 17,430 Mocking library2.0 NAnt Sourceforge 56,529 Build tool3.5 NHibernate Sourceforge 330,374 Object-relational mapper3.5 NUnit Launchpad 85,439 Unit testing framework4.0 Patterns & Practices - Prism Codeplex 146,778 Library to build flexible WPF and Silverlight applications3.5 RhinoMocks GitHub 23,459 Mocking framework2.0 SharpZipLib Sourceforge 25,691 Compression library2.0 Spring.NET GitHub 183,772 Framework for enterprise applications2.0 xUnit.net Codeplex 23,366 Unit testing framework

Table I.NET projects in study’s corpus (versions as of 19 June 2011)

II. METHODOLOGY

A. Research hypothesis

Platforms such as JSE or .NET leverage programminglanguage concepts in a systematic manner to make thoseframeworks reusable (say, extensible, instantiatable, or con-figurable). It is challenging to understand the reuse charac-teristics of frameworks and actual reuse in projects at a highlevel of abstraction. Software metrics on top of simple staticand dynamic program analysis are useful to infer essentialhigh-level reuse characteristics.

B. Research questions

1) What are the interesting and helpful high-level char-acteristics of frameworks with regard to their potentialand actual reuse?

2) To what extend can those characteristics be computedwith simple metrics subject to simple static and dy-namic program analysis?

C. Research method

We applied an explorative approach such that a larger setof metrics of mainly structural properties was incrementallyscreened until a smaller set of key metrics and derivedclassifiers emerged. We use infographics (such as Figure 1)to visualize metrics, classifiers, and other characteristicsof frameworks and projects that use them. The resultingclaims are subject to validation by domain experts for theframework under study.

D. Study subject

The subject of study consists of the Microsoft .NETFramework and a corpus of open-source .NET projectstargeting different versions of .NET (2.0, 3.5, 4.0).

.NET (4.0) has 401 namespaces in total, but we groupthese namespaces reasonably, based on the tree-like or-ganization of their compound names. For instance, allnamespaces in the System.Web branch provide web-related

functionality and can be viewed as a single namespace. Inthis manner, we obtained the manageable number of 69namespaces; see Table II.4 In the rest of the paper, we signifygrouping by “*” as in System.Web.*. Grouping is often usedin discussions of .NET—also by Microsoft.5

Table I collects metadata about the corpus of the study.The following text summarizes the requirements for the cor-pus and the process of its accumulation; more informationis available from the paper’s website.

One requirement is that the corpus is made up from well-known, widely-used and mature projects. We assume thatsuch projects make good use of .NET.

Another requirement is that dynamic analysis must befeasible for the projects of the corpus. This requirementimplies practically that we need projects with good availabletestsuites. The need for testsuites, in turn, implies practicallythat the corpus is made up from frameworks or libraries asopposed to, e.g., interactive tools. Admittedly, advanced test-data generation approaches could be used instead [5].

Yet another requirement is that the corpus is made up fromopen-source projects so that our results are more easily re-producible. Also, the instrumentation for static and dynamicanalysis would be problematic for proprietary projects whichusually commit to signed assemblies.

We searched CodePlex, SourceForge, GitHub, and GoogleCode applying the repository-provided ranking for popu-larity (preferably based on downloads). For the topmostapprox. 30 projects of each repository we checked all therequirements, and in this manner we identified a diverse setof projects as shown in Table I. These projects all use C#as implementation language. (In principle, our approach isprepared to deal with other .NET languages as well—sincethe analysis uses bytecode engineering.)

4We also excluded some namespaces that are fully marked as obsoleteand an auxiliary namespace, XamlGeneratedNamespace, used only by theworkflow designer tool.

5http://msdn.microsoft.com/en-us/library/gg145045.aspx

III. REUSE-RELATED METRICS FOR FRAMEWORKS

We consider the as-implemented design of a framework—without considering any client code (i.e., ‘projects’). Wedefine reuse-related metrics for frameworks and screen themfor .NET. We explain the metrics specifically in the formas they are needed for a composite framework (such as.NET) which consists of many component frameworks—towhich we refer here as namespaces for better distinction.We usually consider metrics per namespace. Some of themetrics are specific to .NET’s type system.

A. Definition of metrics

The ‘overall potential for reuse’ is described by thefollowing metrics:6 # Types—the number of (visible, sayreusable) types declared by a namespace; # Methods—thenumber of (visible, say reusable) methods declared by anamespace.

The types (say, type declarations) of a namespace breakdown into percentages as follows: % Interfaces, % Classes,% Value types, and % Delegate types. If a namespacehas relatively few classes, then this may hint at intended,potential reuse that is different from classic, class-orientedOO programming. In the sequel, we refer to classes andinterfaces as OO types. Further, % Generic types denotesthe percentage of all types that are generic. Relatively manygeneric types hint at a framework for generic programming.Further, the classes of a namespace break down into per-centages as follows; likewise for methods: % Static classes,% Abstract classes, and % Concrete classes.7 Clearly,abstract classes and methods hint at potential reuse of theframework by specialization. Static classes hint at non-OOlibraries and associated, different forms of reuse.

There are metrics for ‘specializability and sealedness’of namespaces: % Specializable classes—the percentage ofall classes that are either abstract or concrete but non-sealed, thereby excluding static and sealed classes; % Sealedclasses—the percentage of all concrete classes that aresealed (final). Sealing explicitly limits reuse by specializa-tion. The aforementioned metrics can also be taken to themethod level. Further, we can incorporate interfaces intoa metric for specializability: % Specializable types—thepercentage of all OO types (i.e., all classes and interfaces)that are either specializable classes or interfaces—the latterbeing all specializable by definition. There are OO types that

6In the case of .NET, non-private, non-internal types and methodsare considered. Properties (in the .NET sense) are considered here asmethods, which they are indeed at the byte-code level. All (visible) methoddeclarations are counted separately. For instance, the initial declaration ofa method as well as all overrides are counted separately. Overloads arecounted separately, too.

7In .NET, value types include structs and enum types. Static classesare not considered concrete classes; neither are they considered abstractclasses—regardless of encoding in MS IL; they are counted separately here.A delegate type is essentially a method type; they are counted separatelyhere—regardless of the encoding in MS IL where delegate types derivefrom class System.Delegate.

must be specialized before they can be reused in client code;we refer to them as orphan types subject to the followingmetrics: % Orphan classes—the percentage of all abstractclasses that are never concretely implemented within theframework; % Orphan interfaces—the percentage of allinterfaces that are never implemented within the framework;% Orphan types—the percentage of all abstract classes andinterfaces that are either orphan classes or orphan interfaces.

‘Inter-namespace reuse’ is described by these metrics:# Referenced namespaces—the number of namespaces thatare referenced by a given namespace; # Referring name-spaces—the number of namespaces that are referring to agiven namespace. Obviously, one can also define metrics for‘inter-namespace specialization’; this is omitted here.

The earlier breakdown of type declarations can bematched by a similar breakdown of type references. Inparticular, type references due to method arguments give riseto % Interface arguments, % Class arguments, % Valuetype arguments, and % Delegate arguments. These met-rics hint at certain forms of reuse. In particular, interfacearguments give rise to interface polymorphism whereas del-egate arguments give rise to closure-based parametrization.

Finally, there are metrics that relate to the degree of‘specialization within a namespace’: MAX size class treeand MAX size interface tree—the size of the largest classor interface inheritance tree in terms of the node count onlyconsidering nodes from the given namespace. (We view aclass as a root of an inheritance tree in the given namespace,if it derives from System.Object or a class in a differentnamespace; likewise for interfaces.) These are reuse-relatedmetrics because, for example, they hint at polymorphism thatcan be leveraged for framework reuse in client code.

B. Measurements for .NET

Table II lists the various metrics for all the .NET name-spaces while sorting namespaces by # Types. We use aninfographics such that most data is not displayed as numbers,but distribution-based visualization is used instead: ‘blank’for zero values and bullets of increasing size, i.e., ‘•’, ‘•’, ‘•’,‘•’, for values in the percentage intervals (0,25), [25,50),[50,75), [75,100) of the distribution. For each column, thecell(s) corresponding to the maximum value for the columndisplay(s) the value instead of ‘•’. Medians as well as 25thand 75th percentiles for all columns are displayed at thebottom of the table.

We total some measurements over all .NET namespaces:

# Types = 12611# OO types = 10103# Classes = 9215# Interfaces = 888# Specializable classes = 5750 (62.4 % of all classes)# Specializable types = 6638 (65.7 % of all OO types)

In accordance with our methodology we grew this set ofmetrics, and we used the infographics of Table II and

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System.Web.* 2327 29315 • • 43 • • • • • • • • • • • • • • •

System.Windows.* • • • 82 • • • • • • • • • • • • • • • • •

System.ServiceModel.* • • • • 43 • • • • • • • • • • • • • • •System.Windows.Forms.* • • • • • • • • • • • • • • • • • • • •

System.Data.* • • • • • • • • • • • • • • • • • • • • •System.Activities.* • • • • • • • • • • • • • • • • • • • • •System.ComponentModel.* • • • • • • • • • • • • • • • • • • • •System.Workflow.* • • • • • • • • • • • • • • • • • • • •System.Xml.* • • • • • • • • • • • • • • • • • • • •System.Net.* • • • • • • • • • • • • • • • • • • • •System.DirectoryServices.* • • • • • • • • • • • • • • • •System • • • • • 69 • • • • • • • • • • • • • • •

System.Security.Cryptography.* • • • • • • • • • • • • • • •Microsoft.VisualBasic.* • • 38 • • • • • • • • • • • 48 • • • • • •System.Runtime.InteropServices.* • • • • • • • • • • • • • • • • •Microsoft.JScript.* • • • • • • • • • • • • • • • • • •System.Drawing.* • • • • • • • • • • • • • • • • • • • •

System.Runtime.Remoting.* • • • • • • • • • • • 23 • • • • • • • •System.Configuration.* • • • • • • • • • • • • • • • • • • • •System.Diagnostics.* • • • • • • • • • • • • • • • • • • •System.IO.* • • • • • • • • • • • • • • • • • • • •

System.Reflection.* • • • • • • • • • • • • • • • • •

System.EnterpriseServices.* • • • • • • • • • • • • • • • •System.CodeDom.* • • • • • • • • • • • • • • • • •

System.IdentityModel.* • • • • • • • • • • • • • • • • • • •Microsoft.Build.* • • • • • • • • • • • • • • • • • •System.Management.* • • • • • • • • • • • • • • • • • • •

System.Threading.* • • • • • • • • • • • • • • • • • • • •

System.Runtime.Serialization.* • • • • • • • • • • • • • • • • • • •System.Security.AccessControl • • • • • • • • • • • • • • •

System.Security.Permissions • • • • • • • • • • • • 86 • •

System.Runtime.CompilerServices • • • • • • • • • • • • • • • • • • • •

System.Linq.* • • • • • • • • • • • 23 • • • • • • • •System.AddIn.* • • • • • • • • • • • • • • • • •System.Xaml.* • • • • • • • • • • • • • • • • • • •System.Messaging.* • • • • • • • • • • • • • • • • •Microsoft.Win32.* • • • • • • • • • • • • • • • • •System.Security.Policy • • • • • • • • • • • • • • • • •

System.Globalization • • • • • • • • • • • •Microsoft.VisualC.* • • • • • • • 100 • • • • 100 100 • •System.Transactions.* • • • • • • • • • • • • • • • • • 100 •System.Security • • • • • • • • • • • • • • •

System.Collections.Generic • • • • • • • • • • • • • • • • • •System.Runtime.DurableInstancing • • • • • • • • • • • • • • • • •

System.Collections • • • • • • • • • • • • • •System.Text • • • • • • • • • • • • • •System.Deployment.* • • • • • • • • • • • • • • •System.Runtime.Caching.* • • • • • • • • • • • • • • • • • 100 •System.ServiceProcess.* • • • • • • • • • • • •System.Resources.* • • • • • • • • • • • • • • •System.Dynamic • • • • • • • • 91 • • • • • 72 • 70System.Security.Principal • • • • • • • • • • • • • •Microsoft.SqlServer.Server • • • • • • • • • • • • • 100 •System.Security.Authentication.* • • • • • • • • • • • • • • •System.Collections.Specialized • • • • • • • • • • • • • • 100 100System.Device.Location • • • • • • • • • • • • • •System.Text.RegularExpressions • • • • • • • • • • • • 100 100 • •Accessibility • • • • • • 60 • • • • 100 100 • •System.Collections.Concurrent • • • • • • • • • • • • 100 100 • •System.Runtime.Versioning • • • • • • • • • • •

Microsoft.CSharp.* • • • • • • • • • • • •System.Collections.ObjectModel • • • • 100 100 • • • • 100 100 • •System.Runtime.ConstrainedExecution • • • • • • • • •

System.Runtime • • • • • • 100 • • •

System.Timers • • • • • 25 • • • • 100 100System.Media • • • • 100 • • • • • •

System.Runtime.Hosting • • • • 100 • • • • •

System.Runtime.ExceptionServices • • • 100 • • •

System.Numerics • • • • 100 • • •75% 190 1579 8 7 22 26 80 16 23 5 1 66 8 46 5 51 89 90 4 40 10Median 60 543 3 2 17 9 72 6 13 0 0 54 4 34 2 33 67 69 1 0 425% 18 175 0 0 11 3 60 0 6 0 0 37 1 19 0 10 46 50 0 0 0

Table IIInfographics for reuse-related metrics for .NET (See the online version for additional data.)

Namespace categories with regard to ‘inter-namespace reuse’:• application if # Referring namespaces = 0.• core if # Referring namespaces is ‘exceptional’.Namespace categories with regard to ‘specializability’:• open if % Specializable types is ‘exceptional’.• closed if % Sealed classes is ‘exceptional’.• incomplete if % Orphan types is ‘exceptional’.Namespace categories with regard to ‘class-inheritance trees’:• branched if MAX size class tree is ‘exceptional’.• flat if MAX size class tree = 0.Namespace categories with regard to ‘intensiveness’:• interface-intensive if % Interface arguments is ‘exceptional’.• delegate-intensive if % Delegate arguments is ‘exceptional’.A sub-category for delegate-intensive namespaces:• event-based if % Delegate types is ‘exceptional’.

Occurrences of ‘exceptional’ are essentially configurable. In thispaper, we assume though that “x is ‘exceptional’ for a namespace”proxies for the statement that the metric x for the given namespaceis in the [75, 100) percentage interval with regard to the distributionfor metric x over all namespaces.

Figure 2. Definition of (non-mutually exclusive) categories

further views (available in the online version of the paper)to develop intuitions about reuse-related characteristics ofnamespaces. The following classification only uses someof the metrics directly, but the other metrics are useful forunderstanding and validation.

IV. CLASSIFICATION OF FRAMEWORKS

In the following, we use the reuse-related metrics to definecategories for reuse characteristics of frameworks—in fact,namespaces. See Figure 2 for the concise definition of thecategories. See Table III for the application of the classifica-tion to a few .NET namespaces that serve as representativesin this section. The section is finished with considerationsof validation.

A. Derivation of the categories

Let us start with ‘inter-namespace reuse’. An applicationnamespace is characterized by the lack of other namespacesreferring to it. That is, no reuse potential is realized for thegiven namespace within the composite framework. Insteadof namespaces with zero referring namespaces, we may alsoconsider namespaces with the most referring namespaces.These are called core namespaces for obvious reasons.

As the medians and other percentiles at the bottom ofTable II indicate, inter-namespace usage is very commonfor .NET. (The appendix of the online version even showssubstantial mutual dependencies.) There are these applica-tion namespaces. The System.AddIn.* namespace provides ageneric framework for framework plug-ins in the sense ofclient frameworks on top of .NET. The Microsoft.VisualC.*namespace supports compilation and code generation forC++. The System.Device.Location namespace allows appli-cation developers to access the computer’s location. TheSystem.Runtime.ExceptionServices namespace supports ad-vanced exception handling for applications.

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System.Web.* X X XSystem.Data.* X XSystem.Activities.* X X XSystem.ComponentModel.* X X X X X XSystem.Xml.* XSystem.DirectoryServices.* X XSystem.EnterpriseServices.* X XSystem.CodeDom.* X XSystem.Linq.* X X XSystem.AddIn.* X X X X XMicrosoft.VisualC.* X X X X XSystem.Transactions.* X X X XSystem.Collections X X XSystem.Runtime.Caching.* X X XSystem.Device.Location X X X XSystem.Runtime.ExceptionServices X X

Table IIIClassification of selected .NET namespaces(See the online version for additional data.)

Perhaps the most obvious representative of a core name-space is System.Collections as it provides collection typesvery much like a library for basic datatypes. Starting atthe top of Table II, the largest core namespace is Sys-tem.ComponentModel.* with its fundamental support forimplementing the run-time and design-time behavior ofcomponents and controls. The next core namespace is Sys-tem.Xml.* with various APIs for XML processing.

Let us consider ‘specializability’. We speak of an opennamespace when the percentage of specializable types is‘exceptional’. We speak of a closed namespace when thepercentage of sealed classes is ‘exceptional’. It will be inter-esting to see whether open namespaces are subject to ‘more’specialization in projects than non-open (or even closed)namespaces. In any case, it is helpful to understand whichnamespaces come wide open and which namespaces limitspecialization explicitly. In this context, another categoryemerges. We speak of an incomplete namespace, when thepercentage of orphan types is ‘exceptional’.

Starting at the top of Table II, the largest open namespaceis System.DirectoryServices.*; it models entities in a network(such as users and printers) and it supports common tasks(such as adding users and setting permissions). The nextopen namespace is System.CodeDom.*; it models an abstractsyntax of .NET languages. These namespaces provide richinheritance hierarchies that are left open for specializationby other frameworks or client code. We mention that Sys-tem.DirectoryServices.* is not specialized within the .NETFramework itself while System.CodeDom.* is specialized byseveral namespaces. Basic knowledge of .NET suggests thatCodeDom is specialized by namespaces that host ‘CodeDomproviders’ and regular projects are actually not very likelyto contain additional providers.

The largest closed namespace is System.Data.*; it sup-ports data access and management for diverse sources—

relational databases specifically. One may expect this name-space to be open because of the need to define a richprovider interface for diverse sources. However, many ofthe classes for data access and management do not dependon the data source, and hence they are sealed. Also, variousproviders, such as SQL Server, Oracle, ODBC, and OleDB,are included into the namespace and accordingly sealed.The next closed namespace is System.Activities.*; it supportsabstract syntax and presentation of activities in a workflowsense. One may expect this namespace to be open becauseof the common design to provide extensibility of syntaxesby inheritance. However, the abstract syntax at hand iseffectively constrained to be non-extensible.

Orphan types are clearly very common in .NET; seeagain Table II.8 The assumption is here that the orphantypes model domain-/application-centric concepts that can-not be implemented in the framework. Let us review thoseincomplete .NET namespaces with all their interfaces be-ing orphans. The System.Transactions.* namespace supportstransaction and resource management; it is referenced byseveral other .NET namespaces—without though imple-menting any of its interfaces. The System.Runtime.Caching.*namespace supports caching; this namespace is only used inthe System.Web.* namespace—without though implementingany of its interfaces.

Let us turn to categories related to ‘class-inheritancetrees’. There are flat namespaces without intra-namespaceclass inheritance. There are branched namespaces with‘exceptional’ inheritance trees. Flat namespaces may bethought of as providing a facade for (some of) the referencednamespaces in the broad sense of the design pattern of thatname. Branched namespaces stand out with a complex objectmodel—complex in terms of tree size.

Starting at the top of Table II, the largest flat name-space is System.EnterpriseServices.*; it supports compo-nent programming with COM+. In particular, .NET ob-jects can be provided with access to resource and trans-action management of COM+. One can indeed think ofSystem.EnterpriseServices.* as a facade. There are manybranched namespaces at the top of Table II; the bigger anamespace, the more likely it contains some sizable treeamong its forest of classes. We previously encountered a‘small’ branched namespace System.CodeDom.* with itsobject model for .NET-language abstract syntax.

Let us finally consider what we call ‘intensiveness’. Aninterface-intensive namespace makes much use of inter-faces for method arguments, thereby supporting reusabilityin terms of interface polymorphism. (This may be seen as

8(Third-party) framework design guidelines for .NET [6] discourageorphan types; a framework designer is supposed to provide implementations(say, concrete classes) for all interfaces and abstract classes. Still orphantypes exist in .NET—presumably because corresponding implementationswould be illustrative rather than reusable and hence better suited for samplesthan for inclusion into the framework assemblies.

a symptom of interface-oriented programming.) There arealso delegate-intensive namespaces, which make much useof delegates for method arguments. Basic knowledge of.NET tells us that delegates are used in .NET for two majorprogramming styles. That is, delegates may be used foreither functional (OO) programming or event-based systems.These two styles cannot be separated easily—certainly notby means of simple metrics. There is a specific form ofan event-based namespace that reveals itself through thedelegate types that it declares.

A clearcut example of a namespace that is, in fact, bothinterface- and delegate-intensive is System.Linq.*; it supportsfunctional (OO) programming specifically for collectionsbased on the IEnumerable interface and friends. We note thatSystem.Linq.* does not declare any delegate type becausethe fundamental function types are readily provided bythe System namespace. There are several namespaces with‘exceptional’ percentages of both delegate arguments anddelegate-type declarations, thereby suggesting themselves ascandidates of the aforementioned, specific form of event-based namespaces; see, for example, System.Web.* right atthe top of Table II—the namespace provides web-relatedfunctionality and uses an event-based style, for example, toattach handlers to user-interface components.

Event-based programming does not necessarily involvedesignated delegate types. Standard delegate types for func-tions or designated interface types may be used as well. Forinstance, the System.Device.Location namespace uses specialinterface types to process updates to the device’s location.Hence, more advanced static analysis would be needed tofind evidence of event-based programming in the form of,for example, subscription protocols or state-based behavior.Further, a strict separation between functional (OO) andevent-based programming is not universally meaningful. Forinstance, the use of asynchronous calls is arguably bothfunctional and event-based. This is an issue with classifyingthe System.Activities.* namespace, for example.

B. Validation of categories

We performed validation to check that the computationallyassigned categories (based on Figure 2) match with theexpectations of domain experts. We discussed each assignedcategory in a manner that one researcher had to provide theconfirmative argument for a category, and another researcherhad to confirm—both researchers (in fact, authors) beingknowledgable in .NET.

In this process, we decided to focus on search for falsepositives and neglect search for false negatives on thegrounds of the argument that the metrics-based categorydefinitions are designed to find ‘striking’ true positives only.Nevertheless, we offer an example of a false negative forbetter understanding. The System.Data.* namespace shouldarguably be classified as a delegate-intensive namespace. Infact, the namespace leverages functional (OO) programming

in the way that data providers are LINQ-enabled. However,the actual percentage of delegate usage does not meet thethreshold of the category’s definition.

V. COMPARISON OF POTENTIAL AND ACTUAL REUSE

We consider the as-implemented usage of a framework.Our main interest is to infer how projects ‘typically’ usethe framework. We define corresponding metrics and screenthem for .NET and the corpus of .NET projects of this study.

A. Definition of metrics

The metric % Referenced OO types denotes the percent-age of all OO types of a given namespace (or the entireframework) that are actually referenced (say, reused) in agiven project (or the entire corpus). The following metricsare defined ‘relative’ to the referenced OO types as opposedto all types.

In §III, we considered specializable types; the correspond-ing relative metric is % Specializable types (rel.)—thepercentage of all referenced OO types that are specializable.Likewise, the metric % Specialized types (rel.) denotesthe percentage of specializable, referenced types that wereactually specialized in projects. Finally, the metric % Late-bound types (rel.) denotes the percentage of specializable,referenced types that were actually bound late in projects.We say that a framework type is bound late in a project,if there is a method call with the framework type as staticreceiver type and a project type as runtime receiver type.(Clearly, said project type directly or indirectly specializessaid framework type.)

B. Measurements for .NET

We summarize measurements for the corpus:• 44 namespaces (out of 69) are referenced.• 22 namespaces are specialized.• 15 namespaces are bound late.• 925 classes (10.0 % of all classes) are referenced.• 105 interfaces (11.8 % of all interfaces) are referenced.• 173 types (2.6 % of all specializable types) are specialized:

– 107 classes (1.9 % of all specializable classes)– 66 interfaces (7.4 % of all interfaces)∗ 30 interfaces are inherited.∗ 66 interfaces are implemented.9

• 611 static receiver types are exercised.• 142 types (2.1 % of all specializable types) are bound late:10

– 116 classes (2.0 % of all specializable classes)11

– 26 interfaces (2.9 % of all interfaces)

An infographics with details is shown in Table IV; the figurein the paper’s introduction was a sketch of this table. We

9Hence, all .NET interfaces serving as base type in interface inheritancein the corpus are also implemented in the corpus.

10Our analysis cannot find all forms of late binding as discussed in §VI.11The number of types bound late may indeed be greater than the number

of specialized types because late binding relates to static receiver types; oneproject type may have several ancestors in the framework.

order namespaces again by the number of types and weinclude only those ever referenced by the corpus.

The middle block of columns displays actual reuse forall combinations of namespace and project while using thefollowing indicators: ‘–’ denotes infeasible reuse (in thesense that the namespace is not available for the frameworkversion of the project); ‘blank’ denotes no reuse; ‘∗’ or ‘∗’denotes less or more referencing (without specialization);‘N’ or ‘N’ denotes less or more specialization (without latebinding); ‘�’ or ‘�’ denotes less or more late binding. Here,‘less or more’ refers to below versus above median non-zero percentages of referenced OO types, specialized types(rel.), and late-bound types (rel.). Hence, those cells showwhether referencing, specialization, and late binding happenat all, and if so, to what extent (at a coarse-grained level:less versus more).

The columns on the left summarize potential reusefor each namespace in terms of the metrics # Types and% Specializable types from Table II.

The columns on the right summarize actual reuse in termsof a ‘dominator’ (i.e., the dominating form of reuse) andthe actual reuse metrics defined above. The dominator isdetermined as follows—without taking into account extentof reuse (‘less or more’). If a namespace is not reusedby more than half of all projects, then the dominator cellremains empty; see, e.g., System.CodeDom.*. Otherwise, if‘referencing’ is more frequent than ‘specialization’ and ‘latebinding’ combined, then the dominator is ‘∗’; in the oppositecase, the dominator is ‘N’ or ‘�’—whatever reuse formis more frequent. For instance, namespace System is usedwith late binding in most projects. Hence, actual reuse issummarized as ‘�’.

C. Discussion

The corpus misses several .NET namespaces totally—including all application namespaces (see Table III) andvarious namespaces related to user interfaces—the lattermost likely due to our methodology; see §II.

The online version determines correlations between var-ious metrics. We state one interesting correlation here: thepercentage of referenced OO types is inversely correlatedwith the size of the namespace (in terms of the number oftypes). Hence, it may be possible to identify an ‘essentialcore’ for each of the largest namespaces.

Let us study the metrics by reviewing all those name-spaces that are referenced but not specialized by the cor-pus. There are 21 namespaces like this and they are allspecializable, in principle. Nine of these namespaces arein the upper half of the distribution for % Specializabletypes. (See, for example, namespaces System.Globalizationand System.Text.RegularExpressions with ‘exceptional’ spe-cializability.) The referenced OO types are only slightly lessspecializable. That is, eight namespaces are in the upperhalf of the distribution for % Specializable types (rel.). Thus,

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Framework 3.5 4.0 3.5 4.0 4.0 2.0 4.0 4.0 2.0 3.5 3.5 4.0 3.5 2.0 2.0 2.0 2.0System.Web.* 2327 • N N N ∗ ∗ � • • • •System.Windows.* • • – – � – – – – • • • •System.ServiceModel.* • • – – N – – – – • • •System.Windows.Forms.* • • � N • • • •System.Data.* • • ∗ ∗ ∗ ∗ N N ∗ • • •System.ComponentModel.* • • ∗ � N � � N ∗ � N N N � ∗ � • • • •System.Xml.* • • ∗ � ∗ ∗ ∗ ∗ N ∗ ∗ � ∗ ∗ • • • •System.Net.* • • ∗ ∗ ∗ ∗ ∗ ∗ • •System • • � � � � � N � � � � � � � � � N � � • • • •System.Security.Cryptography.* • • ∗ N ∗ • • •System.Runtime.InteropServices.* • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •

Microsoft.VisualBasic.* • • ∗ ∗ • •

System.Drawing.* • • ∗ ∗ ∗ • •

System.Runtime.Remoting.* • • ∗ ∗ ∗ ∗ ∗ � ∗ � ∗ N ∗ • • • •System.Configuration.* • • N ∗ N N N N N ∗ � N N ∗ N • • • •System.Diagnostics.* • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ N ∗ ∗ • • •System.IO.* • • ∗ ∗ N ∗ ∗ � ∗ ∗ � ∗ � � ∗ ∗ ∗ � � ∗ • • • •System.Reflection.* • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •

System.EnterpriseServices.* • • ∗ • •

System.CodeDom.* • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •Microsoft.Build.* • • N ∗ • • •System.Threading.* • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ N ∗ ∗ ∗ ∗ • • •System.Runtime.Serialization.* • • ∗ N ∗ N N N N ∗ N N ∗ ∗ ∗ N ∗ ∗ N N • • 75System.Security.Permissions • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ •

System.Runtime.CompilerServices • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •

System.Linq.* • • ∗ ∗ ∗ ∗ ∗ – ∗ � – � ∗ ∗ – – – – ∗ • • • •System.Messaging.* • • ∗ • 100Microsoft.Win32.* • • ∗ ∗ ∗ ∗ • •

System.Security.Policy • • ∗ ∗ ∗ ∗ ∗ •

System.Globalization • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •

System.Transactions.* • • N ∗ ∗ • • •System.Security • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •

System.Collections.Generic • • � � ∗ � � ∗ � N ∗ � � � � N � � � • • • •System.Text • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • •

System.Collections • • � N � N N � � N � � � N � � � N � � • • • •System.ServiceProcess.* • • ∗ • 100System.Resources.* • • ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ � ∗ ∗ ∗ • • • •System.Security.Principal • • ∗ ∗ ∗ ∗ • 100System.Collections.Specialized • 100 N � � ∗ � ∗ ∗ N ∗ � ∗ � 86 100 • •System.Text.RegularExpressions • 100 ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ ∗ • 100System.Runtime.Versioning • • ∗ ∗ ∗ ∗ ∗ ∗ •

System.Collections.ObjectModel • 100 � � � � � ∗ � � ∗ ∗ ∗ � � • 100 • 50Microsoft.CSharp.* • • ∗ ∗ ∗ • 100System.Timers • 100 ∗ ∗ • 100# Referenced types 137 301 245 229 277 229 201 174 375 374 437 213 135 604 308 113 193# Specialized types 16 39 28 26 27 20 18 13 26 39 31 29 10 73 19 11 26# Late bound types 6 7 9 10 11 3 6 4 10 12 20 11 8 22 5 2 875 % 235 89 33 92 33 8Median 80 73 20 75 6 025 % 36 54 12 50 0 0

Table IVInfographics for comparing potential and actual reuse for .NET (See the online version for additional data.)

low (high resp.) specialization is not predicted by low (highresp.) specializability in any obvious sense.

Most namespaces are actually referenced by enoughprojects to get assigned an actual reuse summary in the formof a dominator. This suggests that the projects of the corpusindeed share a ‘profile’ in an informal sense.

Let us compare potential reuse in terms of specializabilitywith actual reuse in terms of the dominator. There areeight namespaces with dominator ‘N’ or ‘�’. Half of thesenamespaces contribute to the System.Collections.* hierarchyand the associated specializability is ‘exceptional’. How-ever, specializability is ‘non-exceptional’ for the remaining

cases; specializability is, in fact, in the percentage interval(0,25) for two cases; see namespaces System.Configuration.*and System.Runtime.Serialization.*. This observation furtherconfirms that high specialization is not predicted by highspecializability in any obvious sense.

VI. THREATS TO VALIDITY

There are the following threats to internal validity. Weuse homegrown tools in the study, especially for bytecodeinstrumentation, for the analysis of .NET design and usage.More subtly, there are threats due to the model underlyingour research. First, while investigating potential and actual.NET reuse, we focus on type specialization—even thoughframeworks might be also configured via attributes (i.e.,annotations) or XML files. This applies to a number of .NETnamespaces. Second, we observe late binding based solelyon the calls from client code to the framework, while itmight also be the case that the framework calls into theclient code through callbacks. Further, the analysis of latebinding relies on the runtime data gathered from the testsuiteexecution. Coverage of method-call sites is incomplete; thetests do not cover 38.96 % of the method-call sites in theprojects of the study.

The major threat to external validity is that though wesystematically collected our corpus, the generalization ofthe results might be biased because of the corpus’ size andcontent as well as the selection criteria.

VII. RELATED WORK

Software metrics are leveraged in our work for exploringreuse characteristics and the alignment between potentialand actual reuse. Elsewhere, metrics are typically used tounderstand maintainability [7] or quality of the code anddesign [8], [1], [9]. There is also a trend to analyze thedistribution characteristics for metrics and the correlationbetween different metrics [10], [11]. In the context of OOprogramming, work on metrics typically focuses on Java; thework of [12] targets .NET with a few basic metrics withoutfocus on reuse.

Type specialization (including class and interface inheri-tance, interface implementation, overriding) is at the centerof attention in our work; there is related work that studies re-lated metrics—without though the objective of summarizingreuse characteristics at a high of level of abstraction. Thework of [13] studies structural metrics of Java bytecode;some reuse-related measurements are covered, too, e.g.,the number of types that inherit from external frameworktypes, or the most implemented external interfaces. The workof [14], [15] focuses on metrics for inheritance and overrid-ing for Java, and it shows, for example, that programmersextend user-defined types more often than external library orframework types. In those works, depth of inheritance treesis considered relevant whereas our metrics-based approachfavored size of inheritance trees since we are interested in

the number of types participating in specialization. The workof [16] analyzes instantiations of frameworks (Eclipse UI,JHotDraw, Struts), though for a purpose of detecting usagechanges in the course of framework evolution. None of theaforementioned efforts involve dynamic analysis.

Static analysis of API or framework usage often addressreuse-related concerns, which are however complementaryto our notion of framework profile. The work of [17]leverages metrics to determine the popularity of the EclipseAPI. Research on API popularity in Java is also presentedin [18]; the authors analyze import statements in open-sourcesoftware to detect and predict changes in usage of APIsover time. The work [19] (co-authored by two of the presentauthors) and [20] analyzes popularity of the Java standardAPI in several dimensions. The work of [21] analyzes APIusage in Java applications and corresponding, ported C#applications to help with automated migration. There issubstantial interest in analyzing API usage with regard tousage patterns; see, for example, [22]. Usage patterns andour framework profiles provide very different abstractionlevels for reuse-related models.

Dynamic usage analysis is leveraged in our work todiscover late-bound framework types. The resulting com-bination of static and dynamic analysis is also encounteredelsewhere [23], [24]. These efforts are relevant in so far asthey inspired our approach (specifically, our implementation)for aligning static and dynamic receiver types. In particular,the work of [23] deals with the dynamic measurement ofpolymorphism in Java and interprets it from a reuse-orientedpoint of view. Bytecode is instrumented and runtime receivertypes are determined by accessing the virtual machine’sstack—similar to our approach. This work is not focusedthough on reuse of a composite framework.

VIII. CONCLUSION

We presented a new approach to understanding reusecharacteristics of composite frameworks such as JSE or.NET. We applied the approach in an empirical study to.NET and a suitable corpus of .NET projects. The reusecharacteristics include metrics of potential reuse (such asthe percentage of specializable types), categories related toreuse (such as open or closed namespaces), and metrics ofactual reuse (such as the percentage of specialized types).These metrics and the classification add up to what we calla framework profile. Infographics can be used to providedifferent views on framework profiles.

Future work needs to address issues of generality men-tioned in §VI. That is, other forms of framework reuse(in particular, configuration) should be investigated, i.e.,forms that do not use basic OO facets. Another importantdirection concerns partitioning of frameworks into relevantsub-frameworks. Such partitioning will make classificationmore useful. Also, partitioning will identify different rolesof sub-frameworks more clearly for developers.

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[15] E. Tempero, S. Counsell, and J. Noble, “An empirical studyof overriding in open source Java,” in Proceedings of theThirty-Third Australasian Conferenc on Computer Science -Volume 102, ACSC ’10. Australian Computer Society, 2010,pp. 3–12.

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[24] A. Rountev, S. Kagan, and M. Gibas, “Static and dynamicanalysis of call chains in java,” in Proceedings of theACM/SIGSOFT International Symposium on Software Testingand Analysis, ISSTA 2004. ACM, 2004, pp. 1–11.

APPENDIX

This appendix provides additions to the main sections ofthe paper. This information is for the reader’s convenience,and it is only included into the online version of paper. Weurge the reader to view data on the screen, thereby beingable to see the details in the tables and figures. (Please usezooming and rotation features of your PDF viewer.) Thisappendix is not suitable for printing—given the amount ofdata included.

A. Additions to §III1) Additional metrics: We add definitions of a few met-

rics that we only hinted at in §III.Specializability is taken to the method level as fol-

lows. Each namespace can be measured in terms of% Specializable methods, i.e., the percentage of all meth-ods that are either abstract or non-sealed methods—henceexcluding static and sealed as well as non-virtual methods. Ametrics is added for % Sealed methods, i.e., the percentageof “non-overridable virtual methods”—which is the percent-age of all virtual, non-abstract instance method declarationsthat are sealed (including the case that the hosting class issealed entirely).

The notion of orphan types can also be refined as follows.That is, types may be orphaned in a more inclusive sense ifwe focus specifically on composite frameworks. There is thevariation % Local orphan classes: the percentage of all ab-stract classes in a given namespace that are never concretelyimplemented within the given namespace. Likewise, thereis the variation % Local orphan interfaces. These metricsshow us whether there are namespaces that are incompleteby themselves while they are ‘fully illustrated’ by othernamespaces so that they do not count as hosting ‘global’orhpans.

Instead of unspecific usage, ‘inter-namespace specializa-tion’ can also be considered. That is, each namespace canbe measured in terms of # Specialized namespaces, i.e.,the number of namespaces with at least one type that isspecialized (implemented or extended) by a type of thegiven namespace versus # Specializing namespaces, i.e., thenumber of namespaces with at least one type that specializea type of the given namespace. Here, direct relationships forreferences and specialization are counted, only—as opposedto taking the transitive closure of those relations.

Table VIII and Table IX provide additional views on the’inter-namespace referencing’ and ’inter-namespace special-ization’. As we can see from the ’specialization’ view, thereare very few ’top’ namespaces which are heavily specialized;others have noticeable less specialization cases. This alsoto some extend proves the hypothesis that classic forms ofOO-extensibility is not very much exercised within .NETFramework itself; they are rather observable on the limitedset of very specific namespaces (e.g. collections).

2) Additional measurements: Table V and Table V serveas extended versions of Table II: they list all reuse-relatedmetrics for .NET platform (in numbers and infographics).Table VIII and Table IX shed some light on usage andspecialization within .NET. Table X provides informationabout possible correlation between metrics. More detailedinformation about orphan types in .NET is provided byFigure 3 and Table XI (namespaces by frequency of orphantypes and a list of all orphan types).

B. Additions to §IV1) Additional measurements: Table XII lists all name-

spaces, classified automatically based on definitions intro-duced in §IV. Table XIII provides information about possiblecorrelation between categories.

C. Additions to §V1) Illustration of late-bound types: The notion of ‘late-

bound type’ was only explained very briefly in §V. Addi-tional details follow.

We start from the most basic form of framework usage:client code references a framework or a namespace thereof.Such a reference could relate to various language concepts,e.g., a reference to a class in a constructor call, a referenceto a type in the declaration of a method argument, or areference to a base class in a class declaration.

In terms of OO-based reuse of a framework in clientcode, usage in the sense of type specialization is of specialinterest. Yet more advanced usage is resembled by latebinding at the boundary of framework and client code. Weare are concerned here with late binding in the sense thata method call of the client code uses a framework type asstatic receiver type, but the actual runtime receiver type endsup being a type of the client code which necessarily derivesfrom the static receiver type.

For clarity, consider the following client code:

public class MyList<T> : List<T> { ... }public static Program {

public static void printResult(List<Item> l){

...Console.WriteLine("Count: {0}", l.Count);...

}public static void Main(string[] args){

List<Item> r = new MyList<Item>();...printResult(r);...

}}

The client code specializes the framework class List forgeneric collections resulting in a subclass MyList. The clientcode also defines a method printResult that works on theframework type List. In the body of that method, List’s

virtual member Count (which is a property, in fact) isinvoked. Further, the client code instantiates MyList andpasses that list to printResult. Subject to a dynamic programanalysis, it can be determined that late binding is used onList. In fact, in this specific example, an inter-proceduralanalysis would be sufficient as opposed to a full-blowndynamic analysis. In this paper, the term static receivertype refers the receiver type essentially as it is declared inthe source code or as the declaration is recoverable fromthe byte code. Hence, the static receiver type in the calll.Count is List<Item>, but the dynamic receiver type isMyList<Item>.

2) Additional measurements: Actual reuse of .NET plat-form by projects is shown in Table XIV, providing numbersfor the infographics of Table IV. Figure 7 shows how oftenlate binding occurs, while Table XVII lists .NET types thatare bound late in projects. Figure 4 and Figure 5 givedetailed overview of the breakdown of referenced types intolate-bound, specialized, specializable, and non-specializable.Figure 6 provides such breakdown per each namespace, forall types, including non-referenced.

Figure 8 and Figure 9 provide information about .NETinterfaces and classes that were derived/inherited in thecorpus. Figure 10 shows top 30 .NET interfaces that wereimplemented in the corpus. Table XVIII lists .NET orphantypes that were implemented in the corpus.

The derived .NET classes in Figure 9 can be classifiedas follows. Again, collections dominate the picture, fol-lowed by custom attributes (say, annotations) and exceptions.Marginally exercised aspects include conversion, remoting,user interfaces, configuration, I/O, and visitors for LINQ.

The implemented .NET interfaces in Figure 10 can beclassified as follows. The list of interfaces is headed byIDisposable, which is used for the release of resources;primarily, these are unmanaged resources. 12 of the 30interfaces deal with collections. Among the top 10, there areadditionally interfaces for serialization and cloning. In therest of the list, yet other aspects are exercised: comparison,services, streaming, and change tracking.

D. On correlation

Where appropriate, we calculated Spearman’s rank cor-relation coefficient, a non-parametric measure of statisticaldependence between variables. The sign of the coefficientindicates the direction of the association: “+” means thatwhen A increases, B increases, too; “-” means that when Aincreases, B decreases. The value of the coefficient indicatesthe degree of the correlation: “0” means that there is no ten-dency for B to either increase or decrease when A increases;“1” means that A and B perfectly monotonically related.(Please note that correlation does not imply causation!)

Spearman’s rank correlation coefficient is calculated forreuse-related metrics (Table X), for classification of name-spaces (Table XIII), and for actual reuse metrics (Table XV

and Table XVI). Stars highlight statistically significant re-sults: three stars mean that p-value is less than 0.001, twostars mean that p-value is less than 0.01, and one starmeans that p-value is less than 0.05. P-value in its turnis a probability to obtain something like what is observed,assuming that null hypothesis (that there is no correlation)is true. So “statistically significant results” mean that thenull hypothesis can be rejected with low risk of making atype I error (i.e., rejecting the true null hypothesis) and thatthe alternative hypothesis (that correlation is present, withsuch-and-such Spearman’s rho) can be accepted instead.

We neither analyze the results in detail nor interpret them.Let us just mention some of the observed (non-trivial) corre-lations. For instance, there is a positive correlation betweenthe number of types in a namespace and the MAX size classtree within the namespace (Table X), meaning that the moretypes a namespace has, the bigger the maximal inheritancetree of namespace’s classes. According to Table XV, thereis a positive correlation such that the number of late-boundtypes increases with the number specialized types, whichin turn increases with the number specializable, referencedtypes, which in turn increases with the number referencedtypes.

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#Referencednamespaces

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#Specializednamespaces

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-0.2

7*0.

44**

*-0

.07

-0.0

4-0

.70*

**-0

.23

pDA

0.28

*0.

30*

0.38

**0.

220.

29*

0.16

0.30

*-0

.02

0.41

***

0.14

0.11

0.04

-0.2

6*0.

59**

*0.

38**

0.04

0.27

*-0

.21

pStC

0.24

*0.

190.

30*

0.26

*0.

220.

26*

0.39

***

0.29

*0.

180.

140.

070.

20-0

.09

0.07

0.13

0.17

0.18

-0.0

80.

15pA

C0.

28*

0.29

*0.

180.

110.

35**

0.20

0.17

0.36

**0.

230.

48**

*0.

180.

00-0

.15

0.06

0.13

0.12

-0.0

1-0

.06

0.07

-0.0

6pC

rC-0

.02

-0.0

10.

010.

10-0

.10

-0.0

2-0

.03

-0.3

1**

0.03

-0.2

3-0

.14

0.13

0.03

0.07

-0.1

70.

000.

03-0

.06

0.01

-0.3

5**

-0.7

0***

pStM

0.12

0.11

0.17

0.05

0.13

0.05

0.19

0.31

**0.

01-0

.03

-0.0

9-0

.03

0.22

-0.0

10.

01-0

.08

0.09

0.25

*-0

.03

0.59

***

-0.1

2-0

.30*

pAM

0.34

**0.

26*

0.20

0.63

***

0.15

0.51

***

0.19

0.11

0.25

*0.

39**

-0.2

7*0.

80**

*-0

.18

-0.0

70.

110.

38**

0.21

-0.2

1-0

.03

0.10

0.21

-0.0

3-0

.10

pCrM

-0.0

7-0

.05

-0.0

4-0

.27*

0.01

-0.1

8-0

.04

-0.1

80.

06-0

.07

0.37

**-0

.39*

**-0

.16

0.06

-0.1

00.

03-0

.21

-0.1

40.

05-0

.50*

**0.

160.

23-0

.75*

**-0

.39*

**pS

ldC

0.18

0.07

0.17

0.17

0.07

0.13

0.13

0.12

-0.0

50.

100.

060.

040.

18-0

.25*

-0.1

70.

03-0

.14

-0.0

4-0

.28*

0.14

0.03

-0.0

80.

210.

03-0

.09

pSpC

-0.1

0-0

.03

-0.0

9-0

.11

-0.0

1-0

.07

-0.0

5-0

.07

0.13

-0.0

30.

020.

02-0

.26*

0.28

*0.

200.

040.

15-0

.04

0.34

**-0

.09

0.03

0.16

-0.2

9*0.

040.

17-0

.92*

**pS

pT-0

.07

-0.0

2-0

.08

-0.0

1-0

.05

0.02

-0.0

4-0

.07

0.13

0.00

-0.0

80.

18-0

.25*

0.24

*0.

230.

070.

25*

-0.0

60.

32**

-0.0

2-0

.02

0.18

-0.2

4*0.

170.

06-0

.89*

**0.

96**

*pS

ldM

0.15

0.15

0.04

0.29

*0.

110.

48**

*0.

160.

29*

0.20

0.37

**0.

060.

37**

-0.2

8*0.

030.

25*

0.27

*0.

05-0

.05

0.10

0.05

0.24

-0.1

20.

000.

29*

0.00

-0.0

80.

110.

14pS

pM0.

230.

200.

140.

38**

0.11

0.29

*0.

090.

160.

150.

32**

-0.2

20.

40**

*0.

00-0

.02

-0.3

1*0.

150.

06-0

.03

-0.2

6*-0

.05

0.26

*-0

.03

-0.2

5*0.

60**

*-0

.08

0.12

-0.0

40.

03-0

.07

pOC

0.31

**0.

31**

0.29

*0.

170.

37**

0.16

0.29

*0.

230.

41**

*0.

32**

0.25

*-0

.01

-0.3

0*0.

200.

220.

170.

12-0

.10

0.38

**0.

020.

70**

*-0

.49*

**-0

.05

0.20

0.05

-0.1

10.

150.

110.

190.

03pO

I0.

48**

*0.

43**

*0.

49**

*0.

65**

*0.

41**

*0.

40**

*0.

39**

*-0

.11

0.46

***

0.17

-0.1

30.

52**

*-0

.05

0.15

0.05

0.26

*0.

19-0

.22

0.18

0.20

-0.0

10.

040.

080.

52**

*-0

.35*

*0.

21-0

.17

-0.0

9-0

.09

0.43

***

0.12

pOT

0.27

*0.

24*

0.23

0.45

***

0.21

0.26

*0.

17-0

.01

0.36

**0.

20-0

.10

0.48

***

-0.2

10.

110.

220.

170.

27*

-0.1

30.

24*

0.06

0.29

*-0

.16

-0.0

20.

57**

*-0

.30*

-0.0

20.

080.

160.

000.

32**

0.59

***

0.67

***

pLO

C0.

190.

180.

110.

130.

160.

130.

100.

35**

0.21

0.51

***

0.09

0.05

-0.1

90.

010.

160.

090.

14-0

.10

0.16

0.04

0.81

***

-0.6

1***

-0.0

90.

24*

0.07

0.00

0.05

0.04

0.15

0.15

0.80

***

0.00

0.46

***

pLO

I0.

44**

*0.

41**

*0.

43**

*0.

66**

*0.

28*

0.43

***

0.30

*0.

070.

40**

*0.

34**

-0.2

9*0.

62**

*-0

.01

0.18

-0.0

10.

210.

23-0

.14

0.12

0.17

0.04

0.04

0.06

0.59

***

-0.3

6**

0.19

-0.1

4-0

.05

-0.0

10.

51**

*0.

070.

91**

*0.

62**

*0.

07

Tabl

eX

Spea

rman

’sra

nkco

rrel

atio

nco

effic

ient

for

reus

e-re

late

dm

etri

cs

0 10 20 30 40 50 60

System.Runtime.CompilerServicesSystem.Security.Cryptography.*

Microsoft.SqlServer.ServerSystem.Net.*

System.Collections.SpecializedSystem.Collections.Generic

System.Security.PermissionsSystem.Security.Authentication.*

System.Management.*System.Runtime.Caching.*

System.Runtime.Remoting.*System.Runtime.Serialization.*

System.CodeDom.*System.IdentityModel.*

System.Runtime.DurableInstancingSystem.Runtime.InteropServices.*

System.Drawing.*System.Transactions.*

System.Configuration.*System.Windows.Forms.*

System.EnterpriseServices.*System.ServiceModel.*

System.Data.*System.Xml.*

System.Windows.*System.Xaml.*

Microsoft.VisualC.*System.Workflow.*

Microsoft.VsaSystem.Dynamic

Microsoft.JScript.*System.AddIn.*

Microsoft.VisualBasic.*System.Activities.*

System.ComponentModel.*System.Web.*

11111111

2222

333

444

55

66

777

899

1111

1416

1717

4352

Figure 3. .NET namespaces sorted by the number of orphan types

System.Runtime.CompilerServices.CallSiteBinderSystem.Security.Cryptography.Xml.IRelDecryptorMicrosoft.SqlServer.Server.IBinarySerializeSystem.Net.ICredentialPolicySystem.Collections.Specialized.INotifyCollectionChangedSystem.Collections.Generic.SynchronizedKeyedCollection‘2System.Security.Permissions.ResourcePermissionBaseSystem.Security.Authentication.ExtendedProtection.ChannelBindingSystem.Management.Instrumentation.BaseEventSystem.Management.Instrumentation.InstanceSystem.Runtime.Caching.Hosting.IApplicationIdentifierSystem.Runtime.Caching.Hosting.IMemoryCacheManagerSystem.Runtime.Remoting.Channels.IAuthorizeRemotingConnectionSystem.Runtime.Remoting.Services.RemotingClientProxySystem.Runtime.Serialization.IExtensibleDataObjectSystem.Runtime.Serialization.IDataContractSurrogateSystem.CodeDom.Compiler.CodeDomProviderSystem.CodeDom.Compiler.CodeCompilerSystem.CodeDom.Compiler.CodeParserSystem.IdentityModel.Selectors.SecurityTokenManagerSystem.IdentityModel.Selectors.SecurityTokenSerializerSystem.IdentityModel.Selectors.SecurityTokenVersionSystem.Runtime.DurableInstancing.InstancePersistenceCommandSystem.Runtime.DurableInstancing.InstancePersistenceEvent‘1System.Runtime.DurableInstancing.InstanceStoreSystem.Runtime.InteropServices.ComTypes.IDataObjectSystem.Runtime.InteropServices.ComTypes.IAdviseSinkSystem.Runtime.InteropServices.ComTypes.IEnumFORMATETCSystem.Runtime.InteropServices.ComTypes.IEnumSTATDATASystem.Drawing.Design.ToolboxServiceSystem.Drawing.Design.IToolboxUserSystem.Drawing.Design.IPropertyValueUIServiceSystem.Drawing.Design.IToolboxItemProviderSystem.Transactions.IPromotableSinglePhaseNotificationSystem.Transactions.ISinglePhaseNotificationSystem.Transactions.ISimpleTransactionSuperiorSystem.Transactions.IDtcTransactionSystem.Configuration.Install.ComponentInstallerSystem.Configuration.ApplicationSettingsBaseSystem.Configuration.IConfigurationSystemSystem.Configuration.IPersistComponentSettingsSystem.Configuration.ISettingsProviderServiceSystem.Windows.Forms.Design.IMenuEditorServiceSystem.Windows.Forms.Design.ComponentEditorPageSystem.Windows.Forms.AxHostSystem.Windows.Forms.IFileReaderServiceSystem.Windows.Forms.Design.IUIServiceSystem.EnterpriseServices.IPlaybackControlSystem.EnterpriseServices.ITransactionSystem.EnterpriseServices.IProcessInitializerSystem.EnterpriseServices.IProcessInitControlSystem.EnterpriseServices.IServiceCallSystem.EnterpriseServices.IAsyncErrorNotifySystem.ServiceModel.Activities.IWorkflowInstanceManagementSystem.ServiceModel.Activities.IReceiveMessageCallbackSystem.ServiceModel.Activities.ISendMessageCallbackSystem.ServiceModel.Discovery.DiscoveryProxySystem.ServiceModel.Channels.IHttpCookieContainerManagerSystem.ServiceModel.PeerMessagePropagationFilterSystem.Data.TypedTableBase‘1System.Data.Mapping.EntityViewContainerSystem.Data.Objects.DataClasses.ComplexObjectSystem.Data.Objects.DataClasses.EntityObjectSystem.Data.Services.IExpandProviderSystem.Data.Services.Providers.IDataServicePagingProviderSystem.Data.Services.Providers.IDataServiceStreamProviderSystem.Xml.IStreamProviderSystem.Xml.Serialization.Advanced.SchemaImporterExtensionSystem.Xml.XPath.XPathExpressionSystem.Xml.Xsl.IXsltContextVariableSystem.Xml.Xsl.XsltContextSystem.Xml.Xsl.IXsltContextFunctionSystem.Xml.Serialization.XmlSerializerImplementationSystem.Windows.Markup.IQueryAmbientSystem.Windows.Markup.IComponentConnectorSystem.Windows.Markup.IUriContextSystem.Windows.Markup.IValueSerializerContextSystem.Windows.Markup.INameScopeDictionarySystem.Windows.Markup.IProvideValueTargetSystem.Windows.Markup.IXamlTypeResolverSystem.Xaml.IXamlNamespaceResolverSystem.Xaml.XamlDeferringLoaderSystem.Xaml.IXamlNameResolverSystem.Xaml.IAmbientProviderSystem.Xaml.IRootObjectProviderSystem.Xaml.IDestinationTypeProviderSystem.Xaml.IXamlObjectWriterFactorySystem.Xaml.IAttachedPropertyStoreMicrosoft.VisualC.StlClr.Generic.INode‘1Microsoft.VisualC.StlClr.IDeque‘1Microsoft.VisualC.StlClr.IList‘1Microsoft.VisualC.StlClr.IQueue‘2Microsoft.VisualC.StlClr.IPriorityQueue‘2Microsoft.VisualC.StlClr.IStack‘2Microsoft.VisualC.StlClr.IVector‘1Microsoft.VisualC.StlClr.IHash‘2Microsoft.VisualC.StlClr.ITree‘2System.Workflow.Activities.WorkflowWebServiceSystem.Workflow.Activities.Rules.IRuleExpressionSystem.Workflow.Activities.WorkflowSubscriptionServiceSystem.Workflow.ComponentModel.Design.IMemberCreationServiceSystem.Workflow.ComponentModel.Design.IExtendedUIServiceSystem.Workflow.ComponentModel.Design.IExtendedUIService2System.Workflow.ComponentModel.Design.ITypeProviderCreatorSystem.Workflow.Runtime.DebugEngine.IExpressionEvaluationFrameSystem.Workflow.Runtime.DebugEngine.IWorkflowDebuggerMicrosoft.Vsa.IVsaCodeItemMicrosoft.Vsa.IVsaErrorMicrosoft.Vsa.IVsaGlobalItemMicrosoft.Vsa.IVsaItemsMicrosoft.Vsa.IVsaReferenceItemMicrosoft.Vsa.IVsaSiteMicrosoft.Vsa.IVsaPersistSiteMicrosoft.Vsa.IVsaIDESiteMicrosoft.Vsa.IVsaIDEMicrosoft.Vsa.IVsaDTEngineMicrosoft.Vsa.IVsaDTCodeItemSystem.Dynamic.BinaryOperationBinderSystem.Dynamic.ConvertBinderSystem.Dynamic.GetIndexBinderSystem.Dynamic.IInvokeOnGetBinderSystem.Dynamic.InvokeMemberBinderSystem.Dynamic.SetIndexBinderSystem.Dynamic.SetMemberBinderSystem.Dynamic.UnaryOperationBinderSystem.Dynamic.CreateInstanceBinderSystem.Dynamic.DeleteIndexBinderSystem.Dynamic.DeleteMemberBinderMicrosoft.JScript.IErrorHandlerMicrosoft.JScript.IObjectCompletionInfoMicrosoft.JScript.IMethodsCompletionInfoMicrosoft.JScript.Vsa.BaseVsaStartupMicrosoft.JScript.COMMemberInfoMicrosoft.JScript.IDebugTypeMicrosoft.JScript.IDebuggerObjectMicrosoft.JScript.FieldAccessorMicrosoft.JScript.INeedEngineMicrosoft.JScript.MethodInvokerMicrosoft.JScript.IMessageReceiverMicrosoft.JScript.ISite2Microsoft.JScript.IDefineEventMicrosoft.JScript.Vsa.IJSVsaPersistSiteSystem.AddIn.Contract.Collections.IRemoteArgumentArrayListContract

System.AddIn.Contract.Collections.IRemoteArgumentDictionaryEnumeratorContractSystem.AddIn.Contract.Collections.IEnumeratorContract‘1System.AddIn.Contract.Collections.IArrayContract‘1System.AddIn.Contract.Collections.IListContract‘1System.AddIn.Contract.IExecutorExtensionContractSystem.AddIn.Contract.ISerializableObjectContractSystem.AddIn.Contract.Automation.IRemoteTypeContractSystem.AddIn.Contract.Automation.IRemoteEventInfoContractSystem.AddIn.Contract.Automation.IRemoteFieldInfoContractSystem.AddIn.Contract.Automation.IRemoteMethodInfoContractSystem.AddIn.Contract.Automation.IRemotePropertyInfoContractSystem.AddIn.Contract.Automation.IRemoteDelegateContractSystem.AddIn.Contract.IServiceProviderContractSystem.AddIn.Contract.IProfferServiceContractSystem.AddIn.Contract.INativeHandleContractMicrosoft.VisualBasic.Compatibility.VB6.BaseDataEnvironmentMicrosoft.VisualBasic.Compatibility.VB6.IDataFormatDispMicrosoft.VisualBasic.Compatibility.VB6.IRowPositionMicrosoft.VisualBasic.Compatibility.VB6.IRowsetMicrosoft.VisualBasic.Compatibility.VB6.IRowsetChangeMicrosoft.VisualBasic.Compatibility.VB6.IColumnsInfoMicrosoft.VisualBasic.Compatibility.VB6.IRowsetInfoMicrosoft.VisualBasic.Compatibility.VB6.IRowsetIdentityMicrosoft.VisualBasic.Compatibility.VB6.IAccessorMicrosoft.VisualBasic.Compatibility.VB6.IChapteredRowsetMicrosoft.VisualBasic.Compatibility.VB6.IDataFormatMicrosoft.VisualBasic.Compatibility.VB6.IConnectionPointMicrosoft.VisualBasic.Compatibility.VB6.IConnectionPointContainerMicrosoft.VisualBasic.Compatibility.VB6.IEnumConnectionsMicrosoft.VisualBasic.Compatibility.VB6.IEnumConnectionPointsMicrosoft.VisualBasic.Compatibility.VB6.BaseOcxArrayMicrosoft.VisualBasic.CompilerServices.IVbHostSystem.Activities.Presentation.PropertyEditing.CategoryEntrySystem.Activities.Presentation.PropertyEditing.PropertyEntrySystem.Activities.Presentation.PropertyEditing.PropertyEntryCollectionSystem.Activities.Presentation.PropertyEditing.PropertyValueSystem.Activities.Presentation.PropertyEditing.PropertyValueCollectionSystem.Activities.Presentation.PropertyEditing.CategoryEditorSystem.Activities.Presentation.Hosting.IDocumentPersistenceServiceSystem.Activities.Presentation.Hosting.IMultiTargetingSupportServiceSystem.Activities.Presentation.IWorkflowDesignerStorageServiceSystem.Activities.Presentation.IIntegratedHelpServiceSystem.Activities.Presentation.IActivityToolboxServiceSystem.Activities.Presentation.IXamlLoadErrorServiceSystem.Activities.Presentation.Hosting.ICommandServiceSystem.Activities.Presentation.Validation.IValidationErrorServiceSystem.Activities.Presentation.View.IExpressionEditorInstanceSystem.Activities.Presentation.View.IExpressionEditorServiceSystem.Activities.Presentation.IModalServiceSystem.ComponentModel.Composition.IPartImportsSatisfiedNotificationSystem.ComponentModel.DataAnnotations.IValidatableObjectSystem.ComponentModel.Design.IComponentDesignerDebugServiceSystem.ComponentModel.Design.IComponentDesignerStateServiceSystem.ComponentModel.Design.IDesignTimeAssemblyLoaderSystem.ComponentModel.Design.IMultitargetHelperServiceSystem.ComponentModel.Design.ObjectSelectorEditorSystem.ComponentModel.Design.Data.DataSourceDescriptorSystem.ComponentModel.Design.Data.DataSourceGroupSystem.ComponentModel.Design.Data.DataSourceProviderServiceSystem.ComponentModel.Design.Data.DesignerDataStoredProcedureSystem.ComponentModel.Design.Data.DesignerDataTableSystem.ComponentModel.Design.Data.DesignerDataViewSystem.ComponentModel.Design.Data.IDataEnvironmentSystem.ComponentModel.Design.Data.IDesignerDataSchemaSystem.ComponentModel.Design.Serialization.ICodeDomDesignerReloadSystem.ComponentModel.Design.EventBindingServiceSystem.ComponentModel.Design.UndoEngineSystem.ComponentModel.Design.Serialization.CodeDomDesignerLoaderSystem.ComponentModel.ISynchronizeInvokeSystem.ComponentModel.INotifyPropertyChangedSystem.ComponentModel.IBindingListViewSystem.ComponentModel.ITypedListSystem.ComponentModel.ISupportInitializeNotificationSystem.ComponentModel.IListSourceSystem.ComponentModel.IEditableObjectSystem.ComponentModel.IDataErrorInfoSystem.ComponentModel.INotifyPropertyChangingSystem.ComponentModel.Design.IRootDesignerSystem.ComponentModel.Design.DesignerOptionServiceSystem.ComponentModel.ComponentEditorSystem.ComponentModel.ContainerFilterServiceSystem.ComponentModel.IComNativeDescriptorHandlerSystem.ComponentModel.IIntellisenseBuilderSystem.ComponentModel.InstanceCreationEditorSystem.ComponentModel.IRevertibleChangeTrackingSystem.ComponentModel.Design.TypeDescriptionProviderServiceSystem.ComponentModel.TypeListConverterSystem.ComponentModel.Design.IComponentDiscoveryServiceSystem.ComponentModel.Design.IHelpServiceSystem.ComponentModel.Design.ITypeDiscoveryServiceSystem.ComponentModel.Design.ITypeResolutionServiceSystem.ComponentModel.Design.Serialization.MemberRelationshipServiceSystem.Web.UI.Design.DesignTimeResourceProviderFactorySystem.Web.UI.Design.IContentResolutionServiceSystem.Web.UI.Design.IControlDesignerTagSystem.Web.UI.Design.IControlDesignerViewSystem.Web.UI.Design.IDesignTimeResourceProviderFactoryServiceSystem.Web.UI.Design.IDesignTimeResourceWriterSystem.Web.UI.Design.IDocumentProjectItemSystem.Web.UI.Design.IFolderProjectItemSystem.Web.UI.Design.IHtmlControlDesignerBehaviorSystem.Web.UI.Design.IProjectItemSystem.Web.UI.Design.IControlDesignerBehaviorSystem.Web.UI.Design.IWebAdministrationServiceSystem.Web.UI.Design.IWebApplicationSystem.Web.UI.Design.IWebFormReferenceManagerSystem.Web.UI.Design.IWebFormsBuilderUIServiceSystem.Web.UI.Design.IWebFormsDocumentServiceSystem.Web.Hosting.AppDomainProtocolHandlerSystem.Web.Hosting.ProcessProtocolHandlerSystem.Web.Caching.OutputCacheProviderSystem.Web.Compilation.IAssemblyPostProcessorSystem.Web.Hosting.IProcessHostPreloadClientSystem.Web.Hosting.IProcessHostSupportFunctionsSystem.Web.Hosting.IProcessPingCallbackSystem.Web.Hosting.IListenerChannelCallbackSystem.Web.Hosting.IApplicationPreloadUtilSystem.Web.Management.IWebEventCustomEvaluatorSystem.Web.IPartitionResolverSystem.Web.Routing.UrlRoutingHandlerSystem.Web.SessionState.IPartialSessionStateSystem.Web.SessionState.IReadOnlySessionStateSystem.Web.UI.IResourceUrlGeneratorSystem.Web.UI.IThemeResolutionServiceSystem.Web.UI.IUserControlTypeResolutionServiceSystem.Web.UI.Adapters.PageAdapterSystem.Web.UI.PageParserFilterSystem.Web.UI.PageThemeSystem.Web.UI.WebControls.WebParts.IVersioningPersonalizableSystem.Web.UI.WebControls.WebParts.IWebPartRowSystem.Web.UI.WebControls.WebParts.IWebPartTableSystem.Web.Util.IWebPropertyAccessorSystem.Web.DynamicData.QueryableFilterUserControlSystem.Web.ClientServices.Providers.IClientFormsAuthenticationCredentialsProviderSystem.Web.UI.ExtenderControlSystem.Web.UI.ScriptControlSystem.Web.Query.Dynamic.DynamicClassSystem.Web.Compilation.IWcfReferenceReceiveContextInformationSystem.Web.Script.Serialization.JavaScriptConverterSystem.Web.UI.Design.MobileControls.IMobileWebFormServicesSystem.Web.Services.Protocols.SoapExtensionSystem.Web.Services.Protocols.SoapExtensionAttributeSystem.Web.Services.Description.SoapExtensionImporterSystem.Web.Services.Description.SoapExtensionReflector

Table XIList of .NET orphan types

Namespace App

licat

ion

Cor

e

Ope

n

Clo

sed

Inco

mpl

ete

Bra

nche

d

Flat

Inte

rfac

e-in

tens

ive

Del

egat

e-in

tens

ive

Eve

nt-b

ased

4 18 20 20 19 20 20 19 21 12System.Web.* X X XSystem.Windows.* X X XSystem.ServiceModel.* X X XSystem.Windows.Forms.* X X XSystem.Data.* X XSystem.Activities.* X X XSystem.ComponentModel.* X X X X X XSystem.Workflow.* X XSystem.Xml.* XSystem.Net.* X XSystem.DirectoryServices.* X XSystem X X XSystem.Security.Cryptography.* XMicrosoft.VisualBasic.* X X XSystem.Runtime.InteropServices.* X X X XMicrosoft.JScript.* X X XSystem.Drawing.* XSystem.Runtime.Remoting.* X XSystem.Configuration.* X XSystem.Diagnostics.* XSystem.IO.* X XSystem.Reflection.* X XSystem.EnterpriseServices.* X XSystem.CodeDom.* X XSystem.IdentityModel.* XMicrosoft.Build.* X X XSystem.Management.* X X XSystem.Threading.* X X XSystem.Runtime.Serialization.* X X XSystem.Security.AccessControl XSystem.Security.Permissions X X XSystem.Runtime.CompilerServices X XSystem.Linq.* X X XSystem.AddIn.* X X X X XSystem.Xaml.* X X XSystem.Messaging.* XMicrosoft.Win32.* X X XSystem.Security.Policy X XSystem.Globalization X X XMicrosoft.VisualC.* X X X X XSystem.Transactions.* X X X XSystem.Security X X X XSystem.Collections.Generic X X X X X XSystem.Runtime.DurableInstancing XSystem.Collections X X XSystem.Text X XSystem.Deployment.* X X XSystem.Runtime.Caching.* X X XSystem.ServiceProcess.* X XSystem.Resources.*System.Dynamic X X XSystem.Security.PrincipalMicrosoft.SqlServer.Server XSystem.Security.Authentication.* X XSystem.Collections.Specialized X XSystem.Device.Location X X X XSystem.Text.RegularExpressions X XAccessibility X X XSystem.Collections.Concurrent X X XSystem.Runtime.Versioning X XMicrosoft.CSharp.* X XSystem.Collections.ObjectModel X X X XSystem.Runtime.ConstrainedExecution X XSystem.Runtime X XSystem.Timers X X X X XSystem.Media X XSystem.Runtime.Hosting XSystem.Runtime.ExceptionServices X XSystem.Numerics X

Table XIIClassification of .NET namespaces

isApplication isCore isOpen isClosed isIncomplete isBranched isFlat isInterfaceIntensive isDelegateIntensiveisApplication

isCore -0.15isOpen 0.11 -0.09

isClosed -0.02 0.13 -0.41***isIncomplete 0.12 -0.07 0.18 -0.11

isBranched -0.16 -0.09 -0.06 -0.06 -0.04isFlat 0.39*** -0.16 0.23 0.01 0.04 -0.41***

isInterfaceIntensive 0.12 0.08 -0.04 -0.11 0.27* -0.11 0.04isDelegateIntensive -0.03 -0.11 -0.08 -0.35** 0.09 0.13 -0.08 0.09

isEventBased -0.11 -0.01 -0.12 -0.29* -0.03 0.04 -0.21 0.06 0.69***

Table XIIISpearman’s rank correlation coefficient for categories

Nam

espa

ce

#Types

%Specializabletypes

ActiveRecord

CastleCore

MonoRail

Windsor

Json.NET

log4net

MEF

Moq

NAnt

NHibernate

NUnit

Prism

Rhino.Mocks

Spring.NET

xUnit

SharpZipLib

Lucene.Net

Dominator

%Referencedtypes

%Specializabletypes(rel.)

%Specializedtypes(rel.)

%Late-boundtypes(rel.)

Fram

ewor

k3.

54.

03.

54.

04.

02.

04.

04.

02.

03.

53.

54.

03.

52.

02.

02.

02.

0Sy

stem

.Web

.*23

2773

(3,1

,0)

(0,0

,0)

(37,

6,0)

(7,1

,0)

(0,0

,0)

(5,0

,0)

(0,0

,0)

(0,0

,0)

(5,0

,0)

(0,0

,0)

(0,0

,0)

(0,0

,0)

(0,0

,0)

(146

,31,

4)(0

,0,0

)(0

,0,0

)(0

,0,0

)(1

68,3

3,4)

744

.045

5Sy

stem

.Win

dow

s.*

1658

74(0

,0,0

)(0

,0,0

)(0

,0,0

)(0

,0,0

)(0

,0,0

)–

(0,0

,0)

(0,0

,0)

–(0

,0,0

)(0

,0,0

)(3

1,3,

5)(0

,0,0

)–

––

–(3

1,3,

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066

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*96

389

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40,1

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1552

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6,2,

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Mod

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2,3,

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2069

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stem

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l.*35

887

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Syst

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285

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5,0,

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0,0,

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2,0,

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71.4

00

Syst

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6541

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250

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tero

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235

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Syst

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ing.

*19

147

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(0,0

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(2,0

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0,0)

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166.

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Rem

otin

g.*

190

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79.3

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Syst

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ion.

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3,0)

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(0,0

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(1,0

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(32,

7,1)

1759

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5Sy

stem

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gnos

tics.

*17

366

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0,0)

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(4,0

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(34,

1,0)

2047

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0Sy

stem

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123

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5,1,

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3,0,

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5,2,

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,0,1

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2,5,

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68.6

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Syst

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tion.

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342

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(58,

0,0)

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0,0)

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0,0)

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0,0)

(25,

0,0)

(45,

0,0)

(24,

0,0)

(28,

0,0)

(41,

0,0)

(29,

0,0)

(23,

0,0)

(30,

0,0)

(64,

0,0)

(35,

0,0)

(12,

0,0)

(21,

0,0)

(77,

0,0)

6829

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stem

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ces.

*11

144

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0,0)

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(0,0

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(19,

0,0)

1710

.50

0Sy

stem

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598

(0,0

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0,0)

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3394

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icro

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ld.*

9692

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1,0)

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248.

750

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stem

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eadi

ng.*

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0,0)

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0,0)

(5,0

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(2,0

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(8,0

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2633

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Seri

aliz

atio

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7449

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(23,

6,0)

3134

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0Sy

stem

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urity

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mis

sion

s70

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Syst

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lerS

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6951

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0,0)

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2028

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0Sy

stem

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6263

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7,2)

5363

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stem

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5290

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2375

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633

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stem

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4531

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00

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Syst

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4552

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0Sy

stem

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3650

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3646

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stem

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lect

ions

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eric

3197

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2,2)

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9,1)

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0,0)

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4,3)

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6,5)

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5,1)

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3,0)

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6,4)

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1,1)

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6,1)

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3,2)

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Syst

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(2,0

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(2,0

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1266

.70

0Sy

stem

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lect

ions

2592

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5,1)

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7,4)

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7,0)

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5)(4

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3,6,

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8485

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44Sy

stem

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Proc

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*21

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50.0

00

Syst

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Syst

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1875

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3310

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Syst

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Ref

eren

ced

type

s14

330

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123

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517

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938

245

321

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531

711

319

8#

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1639

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2720

1813

2639

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1073

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Lat

ebo

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type

s6

79

1011

36

410

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118

225

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8M

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types totalRefT spbTAbs spbTRel totalSpdTtypes

totalRefT 0.70***spbTAbs 0.99*** 0.70***spbTRel 0.66*** 0.95*** 0.67***

totalSpdT 0.40** 0.62*** 0.43** 0.62***totalLbT 0.22 0.49*** 0.24 0.54*** 0.84***

Table XVSpearman’s rank correlation coefficient for actual reuse metrics (numbers)

pRefT pSpbTAbs pSpbTRel pSpdTAbs pSpdTRel pLBTAbspRefT

pSpbTAbs 0.13pSpbTRel 0.01 0.61***pSpdTAbs 0.39** 0.38* 0.15pSpdTRel 0.26 0.46** 0.17 0.94***pLBTAbs 0.36* 0.34* 0.24 0.83*** 0.75***pLBTRel 0.32* 0.34* 0.22 0.81*** 0.75*** 0.99***

Table XVISpearman’s rank correlation coefficient for actual reuse metrics (percentage)

0 10 20 30 40

050

100

150

Namespaces

# ty

pes

Referenced typesSpecializable types (rel)Specialized types

Figure 4. Breakdown of referenced types - I

Non−specializableSpecializableSpecializedLate−bound

Breakdown of referenced types

Namespaces (ordered decreasingly by the number of types)

Per

cent

age

020

4060

8010

0

Figure 5. Breakdown of referenced types - II

Non−specializable (non−ref)Specializable (non−ref)Non−specializable (ref)Specializable (ref)SpecializedLate−bound

Breakdown of types in terms of usage

Namespaces (ordered decreasingly by the number of types)

Per

cent

age

020

4060

8010

0

Figure 6. Breakdown of types in terms of the actual reuse metrics

NH

ibern

ate

Lu

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it

0%

20%

40%

60%

80%

100%

Project Methods

Late binding

Framework Methods

Figure 7. .NET calls w/ and w/o late binding

0 5 10 15 20 25 30 35 40

System.ComponentModel.IContainerSystem.ComponentModel.ISite

System.ComponentModel.Composition.Primitives.ICompositionElementSystem.Collections.Generic.ICollection`1

System.Collections.IComparerSystem.Linq.IOrderedQueryable`1

System.Linq.IQueryable`1System.Configuration.Internal.IInternalConfigSystem

System.Configuration.Internal.IConfigErrorInfoSystem.Data.IDataReaderSystem.Data.IDataRecord

System.ComponentModel.IEditableObjectSystem.ComponentModel.IRevertibleChangeTracking

System.ComponentModel.IChangeTrackingSystem.ComponentModel.INotifyPropertyChanging

System.ComponentModel.IDataErrorInfoSystem.ComponentModel.Design.IServiceContainer

System.Collections.IListSystem.Collections.IDictionary

System.Linq.IOrderedQueryableSystem.Linq.IQueryable

System.Collections.Specialized.INotifyCollectionChangedSystem.ComponentModel.INotifyPropertyChanged

System.ICloneableSystem.Collections.ICollection

System.IServiceProviderSystem.Collections.Generic.IEnumerable`1

System.Collections.IEnumerableSystem.IDisposable

1111111111122222222222

44

8910

1937

For each interface, the number of sub-interfaces in the corpus are shown.

Figure 8. All .NET interfaces with sub-interfaces in the corpus

System.Collections.Specialized.NameValueCollectionSystem.Xml.XmlElementSystem.Collections.HashtableSystem.ExceptionSystem.Collections.ObjectModel.Collection‘1System.ArraySystem.Collections.Specialized.HybridDictionarySystem.Linq.Expressions.ExpressionSystem.Collections.Specialized.StringCollectionSystem.Collections.Generic.List‘1System.Collections.ArrayListSystem.DelegateSystem.EnumSystem.Xml.XmlNodeSystem.Windows.Forms.ControlSystem.IO.StringWriterSystem.ComponentModel.TypeConverterSystem.Collections.Generic.Dictionary‘2System.Collections.CollectionBaseSystem.Xml.XmlAttributeSystem.Collections.IEnumerableSystem.Collections.Generic.IEnumerable‘1System.IO.MemoryStreamSystem.IO.StreamSystem.IO.TextWriterSystem.Collections.Generic.SortedDictionary‘2System.Windows.Forms.TreeNodeSystem.Web.UI.ControlSystem.Collections.ICollectionSystem.Windows.DependencyObjectSystem.Xml.XmlDocumentSystem.Collections.DictionaryBaseSystem.Windows.FrameworkElementSystem.Web.UI.PageSystem.Collections.Generic.ICollection‘1System.Windows.Forms.ToolStripSystem.Xml.XmlNamespaceManagerSystem.ComponentModel.BindingList‘1System.Web.UI.TemplateControlSystem.MulticastDelegateSystem.Linq.Expressions.ExpressionVisitorSystem.Windows.Forms.FormSystem.Collections.ReadOnlyCollectionBaseSystem.Collections.ObjectModel.KeyedCollection‘2System.Collections.Generic.IList‘1System.Configuration.ConfigurationElementCollectionSystem.ComponentModel.PropertyChangedEventArgsSystem.Collections.IListSystem.IO.StreamReaderSystem.ArgumentExceptionSystem.RandomSystem.Windows.Forms.ScrollableControlSystem.Runtime.Remoting.Proxies.RealProxySystem.IO.BinaryReaderSystem.ComponentModel.ComponentSystem.ComponentModel.MemberDescriptorSystem.ValueTypeSystem.Windows.Forms.StatusBarSystem.Windows.Forms.TreeViewSystem.Windows.Threading.DispatcherObjectSystem.Windows.Controls.Primitives.ButtonBaseSystem.Windows.UIElementSystem.Web.HttpApplicationSystem.Resources.ResourceManager

Table XVIIList of .NET types that are bound late in the corpus

0 20 40 60 80 100 120 140

System.Collections.DictionaryBaseSystem.Collections.Specialized.NameValueCollection

System.Web.UI.PageSystem.Configuration.ConfigurationElementCollection

System.Configuration.ConfigurationElementSystem.Resources.ResourceManager

System.Collections.ObjectModel.KeyedCollection`2System.Linq.Expressions.Expression

System.Web.UI.WebControls.WebControlSystem.Collections.Generic.List`1

System.Collections.Generic.Dictionary`2System.Collections.ArrayList

System.Web.UI.ControlSystem.IO.IOException

System.ComponentModel.EnumConverterSystem.Linq.Expressions.ExpressionVisitor

System.SystemExceptionSystem.IO.TextWriter

System.Collections.HashtableSystem.IO.Stream

System.Windows.Forms.UserControlSystem.Collections.ObjectModel.Collection`1

System.ComponentModel.TypeConverterSystem.Windows.Forms.Form

System.EventArgsSystem.ApplicationException

System.Collections.CollectionBaseSystem.MarshalByRefObject

System.ExceptionSystem.Attribute

223333444555556778

11111112

1717

2325

3851

59135

For each class, the number of subclasses in the corpus are shown.

Figure 9. Top 30 .NET classes inherited in the corpus

0 50 100 150 200 250 300 350

System.ComponentModel.IEditableObjectSystem.ComponentModel.IRevertibleChangeTracking

System.ComponentModel.IChangeTrackingSystem.Data.IDataReaderSystem.Web.IHttpHandlerSystem.Web.IHttpModule

System.Runtime.Serialization.IObjectReferenceSystem.ComponentModel.Design.IServiceContainer

System.Collections.Generic.IList`1System.ComponentModel.INotifyPropertyChanged

System.Collections.Generic.IEqualityComparer`1System.Collections.Generic.IDictionary`2

System.Configuration.IConfigurationSectionHandlerSystem.IComparableSystem.IEquatable`1

System.Collections.IDictionaryEnumeratorSystem.Runtime.Serialization.IDeserializationCallback

System.IServiceProviderSystem.Collections.IList

System.Collections.IComparerSystem.Collections.IDictionary

System.Collections.Generic.ICollection`1System.Runtime.Serialization.ISerializable

System.Collections.ICollectionSystem.ICloneable

System.Collections.Generic.IEnumerator`1System.Collections.Generic.IEnumerable`1

System.Collections.IEnumeratorSystem.Collections.IEnumerable

System.IDisposable

5555677791011121314141416181925283338

6583

117578

155196

118176

185256

303

For each interfaces, the number of implementing classes in the corpus are shown. Note: the full bar counts allimplementations whereas the black part excludes classes that can be reliably classified as being compiler-generated.

Figure 10. Top 30 .NET interfaces implemented in the corpus

Namespace % I/C Implemented types Count

System 28.57 I IServiceProvider 18I IAsyncResult 1

System.Collections 60.00 C DictionaryBase 2C .CollectionBase 38C ReadOnlyCollectionBase 1

System.Collections.ObjectModel 100.00 C KeyedCollection‘2 4

System.Collections.Specialized 100.00 C INotifyCollectionChanged 5

System.ComponentModel.* 12.77 I IEditableObject 5I IRevertibleChangeTracking 5I INotifyPropertyChanging 4I IDataErrorInfo 4I ITypedList 1I Composition.IPartImportsSatis-

fiedNotification1

System.Configuration.* 20.00 C ApplicationSettingsBase 1

System.Runtime.Serialization.* 50.00 I IDeserializationCallback 16C SerializationBinder 1I ISafeSerializationData 1

System.Xml.* 42.86 C Xsl.XsltContext 1I Xsl.IXsltContextFunction 1I Xsl.IXsltContextVariable 1

Table XVIII.NET orphan types implemented in the corpus

Runtime receiver type Specialized .NET Type Static receiver typeNHibernate.Exceptions.GenericADOException System.ApplicationException(C) System.Exception(C)NHibernate.Criterion.Order[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Castle.Components.DictionaryAdapter.XPathContext System.Xml.Xsl.XsltContext(C) System.Xml.XmlNamespaceManager(C)Castle.Components.DictionaryAdapter.IDictionaryBehavior[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Castle.Components.DictionaryAdapter.EditableBindingList1 System.ComponentModel.BindingList1(C) System.Collections.ObjectModel.Collection1(C)Castle.MonoRail.Framework.MonoRailException System.ApplicationException(C) System.Exception(C)Castle.MonoRail.Framework.Tests.Helpers.Month[] System.Array(C) System.Collections.IEnumerable(I)Castle.MonoRail.Framework.Tests.Helpers.Role[] System.Array(C) System.Collections.IEnumerable(I)Castle.MonoRail.Framework.Tests.Helpers.RegistrationEnum[] System.Array(C) System.Collections.IEnumerable(I)Castle.MonoRail.Framework.Tests.Helpers.ProductCategory[] System.Array(C) System.Collections.IEnumerable(I)Castle.MonoRail.Framework.Tests.Helpers.Role2[] System.Array(C) System.Collections.IEnumerable(I)Castle.Core.Pair2[] System.Array(C) System.Collections.IEnumerable(I)Castle.MonoRail.Framework.Tests.Helpers.Role[] System.Array(C) System.Collections.ICollection(I)Castle.MonoRail.Framework.Tests.Helpers.Role[] System.Array(C) System.Collections.IList(I)Castle.Core.DependencyModel[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Newtonsoft.Json.JsonConverter[] System.Array(C) System.Collections.Generic.ICollection1(I)Newtonsoft.Json.JsonContainerAttribute[] System.Array(C) System.Collections.Generic.ICollection1(I)Newtonsoft.Json.JsonConverterAttribute[] System.Array(C) System.Collections.Generic.ICollection1(I)Newtonsoft.Json.JsonPropertyAttribute[] System.Array(C) System.Collections.Generic.ICollection1(I)Newtonsoft.Json.JsonIgnoreAttribute[] System.Array(C) System.Collections.Generic.ICollection1(I)Newtonsoft.Json.Serialization.JsonPropertyCollection System.Collections.ObjectModel.KeyedCollection2(C) System.Collections.ObjectModel.Collection1(C)Newtonsoft.Json.JsonPropertyAttribute[] System.Array(C) System.Collections.Generic.IList1(I)Newtonsoft.Json.JsonConverter[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Newtonsoft.Json.JsonConverterAttribute[] System.Array(C) System.Collections.Generic.IList1(I)Newtonsoft.Json.JsonContainerAttribute[] System.Array(C) System.Collections.Generic.IList1(I)Newtonsoft.Json.Converters.IsoDateTimeConverter[] System.Array(C) System.Collections.Generic.ICollection1(I)Newtonsoft.Json.Converters.IsoDateTimeConverter[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Newtonsoft.Json.Schema.JsonSchemaNodeCollection System.Collections.ObjectModel.KeyedCollection2(C) System.Collections.ObjectModel.Collection1(C)Newtonsoft.Json.Linq.ComponentModel.JPropertyDescriptor System.ComponentModel.PropertyDescriptor(C) System.ComponentModel.MemberDescriptor(C)Newtonsoft.Json.JsonIgnoreAttribute[] System.Array(C) System.Collections.Generic.IList1(I)Newtonsoft.Json.JsonConverter[] System.Array(C) System.Collections.Generic.IList1(I)Newtonsoft.Json.Utilities.EnumValues1 System.Collections.ObjectModel.KeyedCollection2(C) System.Collections.ObjectModel.Collection1(C)Newtonsoft.Json.Tests.Serialization.KeyValueId[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Newtonsoft.Json.Tests.Serialization.Employee[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Newtonsoft.Json.Tests.TestObjects.VersionKeyedCollection System.Collections.ObjectModel.KeyedCollection2(C) System.Collections.ObjectModel.Collection1(C)log4net.Util.ReusableStringWriter System.IO.StringWriter(C) System.IO.TextWriter(C)System.ComponentModel.Composition.Primitives.Export[] System.Array(C) System.Collections.ICollection(I)System.ComponentModel.Composition.Primitives.ExportDefinition[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.ComponentModel.Composition.Primitives.ExportDefinition[] System.Array(C) System.Collections.ICollection(I)System.ComponentModel.Composition.CompositionError[] System.Array(C) System.Collections.ICollection(I)System.ComponentModel.Composition.ReflectionModel.ReflectionParameterImportDefinition[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.ComponentModel.Composition.Primitives.ComposablePartCatalog[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.ComponentModel.Composition.Primitives.ComposablePart[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.ComponentModel.Composition.Primitives.Export[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.ComponentModel.Composition.Primitives.ComposablePartDefinition[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.ComponentModel.Composition.Primitives.ImportDefinition[] System.Array(C) System.Collections.Generic.IEnumerable1(I)System.Lazy2[] System.Array(C) System.Collections.IEnumerable(I)System.ComponentModel.Composition.Primitives.ComposablePartDefinition[] System.Array(C) System.Collections.ICollection(I)NAnt.Core.BuildException System.ApplicationException(C) System.Exception(C)NAnt.Compression.Types.DuplicateHandlingConverter System.ComponentModel.EnumConverter(C) System.ComponentModel.TypeConverter(C)Tests.NAnt.Core.ElementTest1Task+OutputTypeConverter System.ComponentModel.EnumConverter(C) System.ComponentModel.TypeConverter(C)NAnt.Core.LevelConverter System.ComponentModel.EnumConverter(C) System.ComponentModel.TypeConverter(C)NAnt.DotNet.Types.DebugOutputConverter System.ComponentModel.EnumConverter(C) System.ComponentModel.TypeConverter(C)NAnt.Core.Util.CommandLineArgumentException System.ArgumentException(C) System.Exception(C)NHibernate.Cfg.MappingSchema.HbmClass[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmSubclass[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmJoinedSubclass[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmUnionSubclass[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmJoin[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmColumn[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmFilter[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Mapping.ISelectable[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.IEntityPropertyMapping[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Engine.Query.Sql.INativeSQLQueryReturn[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.MappingException System.ApplicationException(C) System.Exception(C)NHibernate.Cfg.MappingSchema.HbmFormula[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Engine.TypedValue[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.Cfg.MappingSchema.HbmMetaValue[] System.Array(C) System.Collections.Generic.ICollection1(I)NHibernate.Type.IType[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Param.IParameterSpecification[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Test.HQL.Ast.Human[] System.Array(C) System.Collections.ICollection(I)NHibernate.Test.HQL.Ast.Human[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.DomainModel.FooComponent[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.DomainModel.Foo[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.DomainModel.FooStatus[] System.Array(C) System.Collections.ICollection(I)NHibernate.DomainModel.FooStatus[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.DomainModel.GlarchProxy[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.DomainModel.FooProxy[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.DomainModel.Qux[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.Hql.Ast.HqlTreeNode[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Hql.Ast.HqlStatement[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Hql.Ast.HqlExpression[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Hql.Ast.HqlWhen[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.DomainModel.NHSpecific.Child[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.Cfg.MappingSchema.HbmParam[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NHibernate.Cfg.MappingSchema.HbmMetaValue[] System.Array(C) System.Collections.Generic.IEnumerable1(I)NUnit.Framework.TextMessageWriter System.IO.StringWriter(C) System.IO.TextWriter(C)NUnit.Core.Test[] System.Array(C) System.Collections.IEnumerable(I)NUnit.Core.Test[] System.Array(C) System.Collections.ICollection(I)NUnit.Core.NUnitException System.ApplicationException(C) System.Exception(C)NUnit.Core.Tests.FrameworkData[] System.Array(C) System.Collections.IEnumerable(I)NUnit.Framework.TestCaseData[] System.Array(C) System.Collections.IEnumerable(I)NUnit.UiException.Tests.Controls.TestCodeBox+TestingCodeBox System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Tests.Controls.TestCodeBox+TestingCodeBox System.Windows.Forms.UserControl(C) System.Windows.Forms.ScrollableControl(C)NUnit.UiException.Controls.CodeBox System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Controls.CodeBox System.Windows.Forms.UserControl(C) System.Windows.Forms.ScrollableControl(C)NUnit.UiException.Tests.Controls.TestCodeRenderingContext+TestingCodeBox System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Tests.Controls.TestCodeRenderingContext+TestingCodeBox System.Windows.Forms.UserControl(C) System.Windows.Forms.ScrollableControl(C)NUnit.UiException.Controls.ErrorList System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Controls.ErrorToolbar System.Windows.Forms.ToolStrip(C) System.Windows.Forms.Control(C)NUnit.UiException.Controls.ErrorPanelLayout System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Tests.Controls.TestErrorList+TestingErrorList System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Controls.ErrorBrowser System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiException.Controls.StackTraceDisplay System.Windows.Forms.UserControl(C) System.Windows.Forms.Control(C)NUnit.UiKit.LongRunningOperationDisplay System.Windows.Forms.Form(C) System.Windows.Forms.Control(C)NUnit.UiKit.TestSuiteTreeView System.Windows.Forms.TreeView(C) System.Windows.Forms.Control(C)CP.Windows.Forms.ExpandingLabel System.Windows.Forms.Label(C) System.Windows.Forms.Control(C)Microsoft.Practices.Prism.Modularity.ModuleInfo[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Castle.Proxies.FrameworkElementProxy System.Windows.FrameworkElement(C) System.Windows.DependencyObject(C)Microsoft.Practices.Prism.Tests.Mocks.MockFrameworkElement System.Windows.FrameworkElement(C) System.Windows.DependencyObject(C)Microsoft.Practices.Prism.Tests.Mocks.MockClickableObject System.Windows.Controls.Primitives.ButtonBase(C) System.Windows.UIElement(C)Microsoft.Practices.Prism.Tests.Mocks.MockClickableObject System.Windows.Controls.Primitives.ButtonBase(C) System.Windows.DependencyObject(C)Microsoft.Practices.Prism.Tests.Mocks.MockFrameworkElement System.Windows.FrameworkElement(C) System.Windows.Threading.DispatcherObject(C)Castle.Proxies.FrameworkElementProxy 2 System.Windows.FrameworkElement(C) System.Windows.DependencyObject(C)Rhino.Mocks.Constraints.AbstractConstraint[] System.Array(C) System.Collections.ICollection(I)Rhino.Mocks.Constraints.AbstractConstraint[] System.Array(C) System.Collections.IEnumerable(I)Rhino.Mocks.Tests.Constraints.FailsOnEqual[] System.Array(C) System.Collections.ICollection(I)Spring.Objects.ISharedStateFactory[] System.Array(C) System.Collections.ICollection(I)Spring.Objects.ISharedStateFactory[] System.Array(C) System.Collections.IEnumerable(I)Spring.Util.ConfigXmlElement System.Xml.XmlElement(C) System.Xml.XmlNode(C)Spring.Objects.PropertyValue[] System.Array(C) System.Collections.IEnumerable(I)Spring.Core.TypeMismatchException System.ApplicationException(C) System.Exception(C)Spring.Aop.Framework.AutoProxy.ApcTestAttribute[] System.Array(C) System.Collections.ICollection(I)Spring.Aop.IAdvisor[] System.Array(C) System.Collections.IEnumerable(I)Spring.Core.TypeConversion.TimeSpanConverter System.ComponentModel.TimeSpanConverter(C) System.ComponentModel.TypeConverter(C)Spring.Objects.Factory.ObjectDefinitionStoreException System.ApplicationException(C) System.Exception(C)Spring.Objects.Factory.NoSuchObjectDefinitionException System.ApplicationException(C) System.Exception(C)Spring.Inventor[] System.Array(C) System.Collections.IEnumerable(I)Spring.Inventor[] System.Array(C) System.Collections.ICollection(I)Spring.Inventor[] System.Array(C) System.Collections.IList(I)Spring.Objects.Factory.ObjectInitializationException System.ApplicationException(C) System.Exception(C)Spring.Util.ConfigXmlDocument System.Xml.XmlDocument(C) System.Xml.XmlNode(C)Spring.Objects.TestObject[] System.Array(C) System.Collections.IEnumerable(I)Spring.Util.FatalReflectionException System.ApplicationException(C) System.Exception(C)Spring.Core.InvalidPropertyException System.ApplicationException(C) System.Exception(C)Spring.Objects.TestObject[] System.Array(C) System.Collections.IList(I)Spring.Core.MethodInvocationException System.ApplicationException(C) System.Exception(C)Spring.Util.Foo[] System.Array(C) System.Collections.IEnumerable(I)Spring.Expressions.IExpression[] System.Array(C) System.Collections.ICollection(I)Spring.Expressions.IExpression[] System.Array(C) System.Collections.IList(I)Spring.Validation.Actions.ErrorMessageAction[] System.Array(C) System.Collections.ICollection(I)Spring.Validation.Actions.ErrorMessageAction[] System.Array(C) System.Collections.IEnumerable(I)NHibernate.PropertyValueException System.ApplicationException(C) System.Exception(C)NHibernate.ADOException System.ApplicationException(C) System.Exception(C)Spring.Objects.Factory.ObjectCreationException System.ApplicationException(C) System.Exception(C)Spring.Aop.Framework.AopConfigException System.ApplicationException(C) System.Exception(C)Spring.Web.Support.MockControl System.Web.UI.UserControl(C) System.Web.UI.Control(C)ASP.withoutresources aspx System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)ASP.withresources aspx System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)ASP.disablessession aspx System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)ASP.maintainssession1 aspx System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)ASP.maintainssession2 aspx System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)ASP.TransferAfterSetResult System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)ASP.TransferAfterSetResult System.Web.UI.Page(C) System.Web.UI.Control(C)ASP.transferaftersetresultsave aspx System.Web.UI.Page(C) System.Web.UI.TemplateControl(C)Spring.Web.UI.Controls.Panel System.Web.UI.WebControls.Panel(C) System.Web.UI.Control(C)Spring.TestSupport.TestUserControl System.Web.UI.UserControl(C) System.Web.UI.Control(C)SpecificationBaseCommand[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Xunit.TestMethod[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Xunit.TestClass[] System.Array(C) System.Collections.Generic.IEnumerable1(I)Xunit.TestMethod[] System.Array(C) System.Collections.IEnumerable(I)Xunit.IResultXmlTransform[] System.Array(C) System.Collections.Generic.IEnumerable1(I)TestableTestClass[] System.Array(C) System.Collections.Generic.IEnumerable1(I)SupportClass+GeneralKeyedCollection2 System.Collections.ObjectModel.KeyedCollection2(C) System.Collections.ObjectModel.Collection1(C)

Table XIXTriples of (latebound, specialized, static receiver]) types when static receiver and specialized are different.