27 September 2007 Kaiser: COMS W4156 Fall 2007 1

COMS W4156: Advanced Software Engineering

Prof. Gail Kaiser

Kaiser+4156@cs.columbia.edu

http://york.cs.columbia.edu/classes/cs4156/

27 September 2007 Kaiser: COMS W4156 Fall 2007 2

.NET Components

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What is .NET?

• An object-oriented software development platform, with– peer to peer multi-language interoperability (as

opposed to Java’s “native methods”)– common intermediate language (CIL)– common language runtime (CLR)– common data representation based on XML

• The C# language is the most comfortable for .NET, but not the only one and not mandatory

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How Does Multi-Language Support Work?

• A compiler from any language compiles an application into CIL (also referred to as MS IL – Microsoft Intermediate Language)

• The compiler also generates metadata in XML – information on the types and named entities (classes, methods, fields, etc.) defined and used in the application

• At runtime, the CIL code is Just-in-Time (JIT) compiled into the target platform’s native code

• The CLR uses the metadata to perform runtime checks for type-safety and security (“managed code”)

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Common Language RuntimeExecution Model

CLR

VBSource code

Compiler

C++C#

Assembly AssemblyAssembly

Operating System Services

MSIL

Common Language Runtime JIT Compiler

Compiler Compiler

Native code

ManagedCode

ManagedCode

ManagedCode

UnmanagedCode

CLR Services

Ngen

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So Where’s the Component Model?

COM+(and Web Services)

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.NET Serviced Components

• COM+ 1.5 = COM 1.0 with performance and scaling improvements

• .NET components derive from the System.EnterpriseServices.ServicedComponent class and use the System.EnterpriseServices namespace

• Must be registered with a COM+ application• But can also use COM+ services outside

components

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Example

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Exampleusing System.EnterpriseServices; using System.Runtime.CompilerServices; using System.Reflection; // Supply the COM+ application name. [assembly: ApplicationName("BankComponent")] // Supply a strong-named assembly. [assembly: AssemblyKeyFileAttribute("BankComponent.snk")]namespace BankComponent

{ [Transaction(TransactionOption.Required)] public class Account : ServicedComponent { [AutoComplete]

public bool Post(int accountNum, double amount) { /* Updates the database; no need to call

SetComplete. Calls SetComplete automatically if no exception is generated. */

return false; } } }

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.NET vs. COM+

• No IUnknown base interface• No reference counting, uses garbage

collection• No class factories, the .NET runtime

resolves to a particular class within an assembly

• No apartments, programmer synchronizes (or uses automatic .NET synchronization domains)

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.NET vs. COM+

• No IDL (Interface Definition Language) files, the compiler generates the assembly metadata and dependencies are captured during compilation (in manifests)

• No GUIDs (globally unique identifiers), instead uses scoping based on namespaces and “strong names” (unique digital signature using an encryption key)

• Evidence-based security (where component came from), in addition to role-based

• Doesn’t rely on registry, reduces DLL Hell

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IDA #3 Due Next Week!

• Tuesday 2 October, 10am

• Assignments posted on course website

• Submit via CourseWorks

• Individual Development Assignment #3

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Upcoming Deadlines

• Revised project concept due October 9th – first iteration begins

• First iteration plan due October 16th • First iteration progress report due October 23rd • First iteration demo week October 30th –

November 8th • First iteration final report due November 9th

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COMS W4156: Advanced Software Engineering

Prof. Gail Kaiser

Kaiser+4156@cs.columbia.edu

http://york.cs.columbia.edu/classes/cs4156/