Mark Friedman Architect Developer Division Microsoft Corporation

Web application Performance

Mark FriedmanArchitectDeveloper DivisionMicrosoft Corporation

Agenda: ASP.NET architecture for building dynamic

web applications Building scalable web applications

Persisting Session state Caching application data n-Tiered application scaling

Building responsive web applications Page Load Time and Round trips AJAX

Tips for Silverlight and WPF-based applications

Web Application Performance

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Framework for developing web sites that generate Dynamic HTML Responses Get Request ↔ Response message

Additional files are frequently embedded in the Response HTML

e.g.,<A HREF="resumepage.html">my resume</A>

Web Browser (e.g., IE) performs HTML layout Frames Tables Images Cascading Style Sheets

<LINK REL=STYLESHEET HREF="mystyles.css" TYPE="text/css">

ASP.NET Application Performance

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From Web Pages to Web Applications aka, Rich Internet Applications (RIA)

Dynamic HTML (Server-side processing) SOAP (Web services) AJAX (Client-side scripting) Silverlight (Client-side runtime) XAML elements (WPF) etc.,

Dynamic HTML is layered on top of the HTTP protocol, which was originally designed to be both connectionless and sessionless. Individual requests are independent of each other No “state” is preserved between one request and

another


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Server-side Request processing Event-oriented programming model (Postback) HttpContext wrapper around the HTTP Request Persistent State

ViewState Session State Application and Page Cache objects etc.


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Client-side scripting Rich Internet Applications (RIA) AJAX

Browser Document Object Model (DOM) Javascript Asynchronous server Postbacks (to web services)


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Measurement considerations On the client

Performance counters Network Monitor traces ETW traces (IE, etc.) Direct measurements inside Javascript code

On the server IIS logs (especially Time-Taken fields) Performance counters

web app response time data is not available ETW traces (IIS, ASP.NET, CLR, etc.)

volume considerations Direct measurement inside .NET code

e.g., Stopwatch


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Measurement considerations End-to-End Multiple tiers


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HTTP application performance is constrained by network latency!


NetworkLatency

Client-sidescript

Server-side.aspx

NetworkLatency

Client-sidescript

Server-side.aspx

NetworkLatency

Client-sidescript

Server-side.aspx

Unit Test Load Test

e.g., VS TeamTest

Production

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Measuring Page Load Time Time to First Byte Network Monitor capture data

DNS Lookup TCP Session handshaking

SYN, SYN-ACK, ACK sequence Calculates 1st Round Trip Time used by Fast

Retransmit logic Dynamic HTML Response message generated by the

ASP.NET application Which can then reference additional files

embedded in the HTML e.g., css, js, jpg, gif, xml, xaml, wmv, etc.

When is the application Ready to use?


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Visual Roundtrip Analyzer

demo

VRTA (Visual Round Trip Analyzer)


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http://www.microsoft.com/downloads/details.aspx?FamilyID=119F3477-DCED-41E3-A0E7-D8B5CAE893A3&displaylang=en

Elements of Page Load Time Html CSS Javascript (serializes) XAML Images Audio Video Banner ads (often from 3rd parties) etc.

Page Load parallelism IE7 limited to two parallel sessions IE8 and Chrome support six parallel sessions


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Pages are assembled from a variety of elements, some of which may reside on different web servers

Static content can be cached: on the client on the server somewhere in-between

Proxy servers Cache engines etc.

Semi-dynamic content may also be cacheable


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Semi-dynamic content generated by ASP.NET server-side code may be cacheable Multiple facilities in IIS/ASP.NET available for

cachingIIS kernel mode CacheASP.NET Application cacheASP.NET Page cache

Virtual memory constraints relieved in x64 OS!

Note: these are complex facilities that may require considerable monitoring & analysis to achieve optimal results.


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Cache performance and efficiency Caching is ubiquitous across the web

In the Browser in the content delivery network infrastructure, on the proxy server on the web server (in multiple forms) on the database server

For the sake of latency, cache data as close to the client as possible Multiple layers of cache hold largely redundant data One effective layer is usually sufficient

See “Caching Architecture Guide for .NET Framework Applications”


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http://msdn.microsoft.com/en-us/library/ms978498.aspx

w3wp.exew3wp.exe

Common Language Runtime (CLR)

JIT compilerGarbage Collection threads

mscoree.dllmscorsvr.dllMyApp.dll

ASP.NET Application Architecture

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Event-driven programming (runat=“server”)

ASP.NET programming model

Form:<asp:DropDownList id="FileDropDownList" style="Z-INDEX: 111; LEFT: 192px; POSITION: absolute; TOP: 240px“ runat="server" Width="552px" Height="40px“ AutoPostBack="True"></asp:DropDownList>

Code behind:Private Sub FileDropDownList_SelectedIndexChanged _ (ByVal sender As System.Object, _ ByVal e As System.EventArgs) _ Handles FileDropDownList.SelectedIndexChanged Session("FileSelected") = FileDropDownList.SelectedValueEnd Sub

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IIS Architecture

User

Kernel

HTTP

TCP

IP

Network Interface

HTTP Kernel Mode Driver

(http.sys)

HTTP Response Cache

(Physical Memory)

LSSAS

WindowsAuthentication

SSL

Inetinfo

IIS Administration

FTP

Metabase

SMTP

NNTP

SVCHOST

W3SVC

W3wpW3wp

Mscoree.dll

http

<code-behind>.dll

Default.aspx

Application Pool

W3wpW3wp

Mscoree.dll

<code-behind>.dll

Default.aspx

Application Pool

WAS

Cache

net.tcp net.tcp

http

HTTP Request

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IIS Architecture

Kernel mode driver (http.sys) Dedicated kernel mode

Response object cache Static (jpgs, gifs, etc.) and

semi-dynamic (ASP.NET) content

Accessed using Physical addresses only!

Monitor Web Service Cache\Kernel: Current URIs Cached, etc.

See “IIS 7.0 Output Caching” at http://learn.iis.net/page.aspx/154/iis-7-output-caching/

http://learn.iis.net/page.aspx/154/iis-7-output-caching/

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IIS Architecture

ASP and ASP.NET requests processed by w3wp.exe worker processes

Worker processes are configured into Application Pools managed by the Windows Process Activation Service (WAS) Pool Health options

(including automatic recycling)

Pool Performance options

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IIS Architecture

ASP.NET w3wp.exe worker processes Health monitoring

Performance counters per worker process in IIS 7.0

From a command line: \windows\system32\inetsrv\appcmd list WP

Monitoring IIS worker processes

demo


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ASP.NET services can be made available to non-ASP.NET applications!

ApplicationManager HostingEnvironment

Per Request HttpContext HttpRequest HttpResponse

IIS 7.0 Integrated Pipeline

Request Life-cycle EventsBegin Request Authentication Authorization Resolve Cache Map Handler Acquire State Execute Handler Release State Update Cache Log Request Send Request

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HttpApplication Event Handlers (IHttpModule)

IIS 7.0 Integrated Mode

Event EventBeginRequest PreRequestHandlerExecute

AuthenticateRequest PostRequestHandlerExecute

PostAuthenticateRequest ReleaseRequestState

AuthorizeRequest PostReleaseRequestState

PostAuthorizeRequest PostMapRequestHandler

ResolveRequestCache PostMapRequestHandler

PostResolveRequestCache PostMapRequestHandler

MapRequestHandler UpdateRequestCachePostMapRequestHandler PostUpdateRequestCacheAcquireRequestState LogRequest

PostAcquireRequestState EndRequest

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IIS 7.0 Integrated Mode

Leverage ASP.NET Modules (services) FormsAuthenticationModule ProfileModule RoleManagerModule SessionStateModule

See ApplicationHost.config <modules> section

See Mike Volodarsky, “Explore The Web Server For Windows Vista And Beyond,” MSDN

Magazine, March 2007 “Enhance Your Apps with the Integrated ASP.NET Pipeline,” MSDN

Magazine, January 2008. “Build Web Server Solutions with End-to-End Extensibility,” MSDN

Magazine, March 2008.31

Configure IIS ETW tracing to gather RequestNotification events

Mark FriedmanArchitectDeveloper Division

demo

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Configure IIS Tracing using Logman

IIS: WWW Server Event Trace Provider

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IIS: WWW Server Event Trace Provider Keywords

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IIS: WWW Server Event Trace Provider – Level = 5 (Diagnostic level)

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ETW Trace reporting tools

Post-process etl Trace using tracerpt

tracerpt filename.etl –of CSV –o mytrace.csv

logparser

logparser "select * from filename.etl" -e 20 -o:DATAGRID -rtp 30 -compactModeSep "|"

xperf

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IIS: WWW Server Event Trace Provider Keywords e.g., UseUrlFilter to control the volume of data Configure the TraceUriPrefix Metabase Property

See “How to Trace Requests for a Specific URL or Set of URLs” at http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/c56d19af-b3d1-4be9-8a6f-4aa86bacac3f.mspx?mfr=true

http://www.microsoft.com/technet/prodtechnol/WindowsServer2003/Library/IIS/c56d19af-b3d1-4be9-8a6f-4aa86bacac3f.mspx?mfr=true




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The HTTP protocol is connectionless sessionless

.NET wrappers for HTTP protocol services HttpContext

Provides programmatic access to all properties associated with an HTTP Request

Request Response Session Cache

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.NET wrappers for HTTP protocol services HttpContext.Request

HttpMethod (GET, POST, etc.) URL Cookies collection Headers InputStream UserHostAddress (IP address of the Requestor) etc.

The ASP.NET programming model provides several facilities to persist User/Application state

ASP.NET Page Events

Event UsagePreInit Create dynamic controls, set the Theme; master page, etc.

Init Read or initialize control properties

InitComplete Raised by the Page object.

PreLoad Perform any processing on your page or control before the Load event.

Load The Page calls the OnLoad event method on the Page, then recursively for each child control and its children

Control events Button Clicks and other Control events are processed after Page_Load

LoadComplete Fires after all controls on the page are loaded.

PreRender Data binding for controls occurs now.

SaveStateComplete Fires when the ViewState for all controls is complete and saved.

Render Method that writes out the html markup associated with the control.

Unload Do final cleanup, such as closing files or database connections

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ASP.NET scalability strategies

Session State management ASP.NET Cache n-Tiered applications

e.g., Presentation Layer Business Logic Layer Data Layer

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ASP.NET State Management

What is State? Any information about the user,

his/her history and association with the application that informs the application’s processing.

e.g., how to associate a (potential)

customer with his/her shopping cart?

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Session State management Client-side options

Hidden fields Cookies Query strings (including Web Beacons or Clear GIFs ) View state Control state

Server-side options Application state (HttpApplicationState) Session state Profile Properties

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State by Scope: Application state (HttpApplicationState) Page

Static variables potentially use Page.Cache for dynamic data

Session Client-side options

Query strings Cookies Hidden fields View state Control state

Server-side options Session state Profile Properties


Persisting state on the client on the server

State Management

ViewState Stored in _VIEWSTATE hidden field

ControlState Override if ViewState is turned off on the Page

HiddenField control

Cookies Add cookie data to the Cookies collection in the HttpResponse object

Query strings

Application State HttpApplicationState

Session State

Profiles SqlProfileProvider

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Persisting state on the server (ViewState)

Control ViewState (e.g., a DataGrid control) View state is enabled for all server controls by

default. Additional round trips to the server may be

required to re-send the Control’s ViewState remember, the HTTP protocol is sessionless

Set the control's EnableViewState property to false to disable…

Or, use AJAX functions to eliminate server postbacks so you can maintain ViewState on the client (browser) 48

Inspectingcontrols ViewState

demo

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ASP.NET ViewState

ViewState Passed to the client in _ViewState hidden field in the

Response message Returned to the Server on a postback Request

Inspect using %@ Page Trace="true“ View html Source on the client 3rd party tools like Fiddler

Be careful of Data bound controls (GridView, etc.) Large TreeViews, DropDownLists, etc.


Understanding what is in your ViewState? e.g., ASP.NET ViewState Helper tool from

Binary Fortress Software

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ASP.NET Application State

Page.Application Gets the HttpApplicationState object for the current Web request. Remember: application state must be locked to

update the data stored there correctly:

Application.Lock(); Application["PageRequestCount"] = ((int)Application["PageRequestCount"])+1; Application.UnLock();

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ASP.NET Session state

HttpContext.Session Data associated with a logical sequence of Requests

that need to be persisted across interactions Unique session IDs are passed along automatically

with each Request as either cookies or embedded in the URL

Session data is stored in a Dictionary collection, allowing individual session state variables to be accessed directly by Key name

Three external storage options InProc StateServer SQL Server

Timeout management

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ASP.NET Session

HttpContext.Session InProc option provides fastest service, but does

not permit access to Session data from a different process in a Web garden application or a different Web server in a cluster

Using alternatives to InProc session storage has significant performance implications StateServer SQL Server Custom provider

Measure impact using the IIS RequestNotification events e.g., AcquireRequestState, PostAcquireRequestState

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Session State options

InProc StateServer

Does not require using a separate computer ASP.NET State service must be active Provides persistent state for multiprocess IIS Web gardens with

automatic restart SQLServer

Uses a separate computer where the DB is stored Multicomputer front-end clustering. e.g., Round-Robin DNS Failover on an HA cluster to a secondary copy of SQL Server

Session State configuration options

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Session State optionsFor example,

Run either InstallSqlState.sql or InstallPersistSqlState.sql to create the Session State stored procedures

Code the sessionState attribute in web.config:

<configuration>

<system.web>

<sessionState mode="SQLServer"

sqlConnectionString=" Integrated Security=SSPI;datasource=dataserver;"

cookieless="false"

timeout="20"/>

</sessionState>

</system.web>

</configuration>

Cache objects based on Frequency of re-use Cost to re-generate Size

Optimize:Max(Cache Hit %)

Min(Space x Time)

Caching strategies

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Optimize to: maximize Cache Hit % minimize Cache

memory size Analyze web logs for

patterns of re-use Usually, there are

diminishing returns from increasing cache size to be large enough to hold infrequently referenced objects

ASP.NET Cache

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0 25 50 75 100

Cache Hit %Ca

che

Size

Multiple facilities: e.g.,

IIS kernel mode Cache ASP.NET Application cache ASP.NET Page cache etc.

Which cache facility? e.g., results from a complex database Query

Depends on the scope of the data Application, User, Page (or some combination)

Static vs. Dynamic data

Caching strategies

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Access to large process vm in x64 OS! To be effective, cached data should reside in

physical memory! Caching the same data in multiple places tends

to be wasteful Multiple layers of cache hold largely redundant data For the sake of latency, cache data as close to the client

as possible One effective layer is usually sufficient

Note: effective caching is difficult & complex To achieve optimal results, be prepared to monitor

performance & analyze results.

Caching strategies

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ASP.NET Cache

Application cache HttpContext.Cache Page.Cache

Page output caching Full page

@ OutputCache Directive Use VaryByParam with Query Strings to cache multiple versions of a Page

Partial page Control Caching

<PartialCaching> Attribute Post-cache substitution: dynamically updating portions of a cached page

Substitution.MethodName HttpResponse.WriteSubstitution Method

You can also cache data in the Session object, where appropriate

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ASP.NET Application & Page Cache

What to cache: Frequently used data that is relatively static and expensive to

re-create Additional considerations based on object size

space-time product: frequency of use x object size

The Cache is instrumented using performance Counters But to use Cache effectively, you might need additional

performance data: e.g.,

Enumerate the contents of the Cache Identify and log Underused entries Calculate cache residency times per entry


Steven Smith’s ASPAlliance Cache Manager Plug-in

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Cache object is a hybrid of the Dictionary class with additional methods and properties implements IEnumerable to manage cache effectiveness to help deal with cache synchronization issues

Note: no built-in Lock object ! Locking is not normally required, but may be necessary

to avoid race conditions in special situations

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Cache Methods Add (key, value, dependencies, expiration, sliding

expiration, priority, onRemoveCallback); e.g., Cache.Add("Key1", "Value 1", null,

DateTime.Now.AddSeconds(60), Cache.NoSlidingExpiration, CacheItemPriority.High, onRemove);

Dependencies (permits bulk removal) Notification upon removal

Insert (also overwrites an existing entry) Get Remove

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Cache Object Removal Policy Scavenging (based on Priority)

Low, BelowNormal, Normal, AboveNormal,High NotRemovable

Expiration Dependencies

whenever the underlying data has changed set up an AggregateCacheDependency set up a SqlCacheDependency:

uses SQL Query Notification mechanism when the underlying data Table or View changes

See http://msdn.microsoft.com/en-us/library/system.web.caching.sqlcachedependency.aspx

http://msdn.microsoft.com/en-us/library/system.web.caching.sqlcachedependency.aspx

http://msdn.microsoft.com/en-us/library/system.web.caching.sqlcachedependency.aspx

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Calculate Application Cache effectiveness from the ASP.NET Cache instrumentation Cache API Entries Cache API Hits Cache API Misses Cache API Hit Ratio Cache API Turnover Rate: The number of calls to

the Add, Insert, and Remove Methods per second

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Cache Object Notifications upon removal

public void RemovedCallback (String k, Object v, CacheItemRemovedReason r){}

Examine the CacheItemRemovedReason DependencyChanged Expired Removed

by a Remove method call, or by an Insert method call that specified the same key.

Underused


InstrumentedCacheValue (to be processed by CacheItemRemovedCallback delegate)

public class InstrumentedCacheValue { private object _value; private DateTime _timestamp_added; // unfortunately, it is a sealed class; otherwise… // private Int64 _refcount; // private DateTime _lastreftimestamp; public object Value { get { return _value; } } public DateTime timestamp_added { get { return _timestamp_added; } } public InstrumentedCacheValue(object value){ _value = value; _timestamp_added = DateTime.Now; }}

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Cache Object ReadOnly Properties Count EffectivePrivateBytesLimit

can be set with the privateBytesLimit attribute EffectivePercentagePhysicalMemoryLimit

can be set with the percentagePhysicalMemoryUsedLimit attribute

Cache Configuration Attributes in web.configdisableMemoryCollectiondisableExpirationprivateBytesLimitpercentagePhysicalMemoryUsedLimit privateBytesPollTime="HH:MM:SS"

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ASP.NET Page Output Cache

Page output caching Full page

@ OutputCache Directive Duration parameter (in seconds) Use VaryByParam to cache multiple versions of a Page Location

Any (equivalent to HttpCacheability.Public ) Client, Proxy Server, Edge Server, etc.

Client: (equivalent to HttpCacheability.Private) Server: (equivalent to HttpCacheability.Server) None: (equivalent to HttpCacheability.NoCache) ServerAndClient: (equivalent to

HttpCacheability.Private & to HttpCacheability.Server)

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Programmatically, set the HttpCachePolicy of the Response.Cache object

Response.Cache.SetCacheability(HttpCacheability.Public);

Response.Cache.SetExpires(DateTime.Now.AddSeconds(300));

Response.Cache.SetMaxAge(TimeSpan.FromSeconds(300));

Response.Cache.SetValidUntilExpires(true);Response.Cache.SetLastModified(DateTime.Now);Response.Cache.SetOmitVaryStar(true);

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Programmatically set the Cache-Control header Call Response.Cache.SetCacheability Method and

set the HttpCacheability property

NoCache Public Private (default)

Server ServerAndNoCache PublicAndPrivate

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Calculate Cache effectiveness from the ASP.NET Cache instrumentation Cache Entries Cache Hits Cache Misses Cache Hit Ratio Cache Turnover Rate: The number of calls to the

Add, Insert, and Remove Methods per second

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ASP.NET Partial Page Output Cache

When page caching will not work due to dynamic content

Two partial page caching options: Control caching for user controls

[PartialCaching(120)] public partial class CachedControl : System.Web.UI.UserControl

{ // Class Code } Post-Cache substitution

Banner ads, etc.

ASP.NET & AJAX

Web pages built with ASP.NET Web server controls perform postbacks initiated by clicking a button, etc.

In Response, the server renders a new page. Frequently this re-renders controls and text that did

not change between postbacks. AJAX refers to set of patterns and practices that

perform partial rendering of the page at the client using Javascript and asynchronous HTTP requests Microsoft pioneered the use of AJAX prior to

ASP.NET AJAX support for ASP.NET was not provided

until.NET Framework 3.077

ASP.NET & AJAX

Reduce server Round Tripping using client-side scripting (Responsiveness) Support popular UI elements such as progress bars,

tooltips, pop-up windows Client call-backs (ICallbackHandler) AJAX (Asynchronous JavaScript and XML)

XMLHttpRequest Microsoft AJAX Library on the client (browser) Server controls:

ScriptManager <asp:ScriptManager EnablePartialRendering="True“ />

UpdatePanel UpdateProgress Timer

Web services sending & receiving JSON or XML Web services located in the Cloud

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ASP.NET and AJAX

Asynchronous XMLHttpRequest Note: implementation of XMLHttpRequest is

browser-dependentxmlhttp.open('GET', url, true);xmlhttp.onreadystatechange = AsyncUpdateEvent;xmlhttp.send(null);

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ASP.NET and AJAX

UpdatePanel Control

Define regions of the page that can be updated independently using an XMLHttpRequest converts PostBacks into Asynchronous XML and HTTP Requests Somewhat larger Request messages vs. significantly smaller server Response

messages Flicker-free update Re-sends all Viewstate data, however, for controls within the UpdatePanel

Triggers Property ChildrenAsTriggers Property for controls inside the UpdatePanel

See “Cutting Edge, “AJAX Application Architecture, Part 1” by Dino Esposito for more details 80

http://msdn.microsoft.com/en-us/magazine/cc163363.aspx

Client HTTP Get Request

Sys.Application.Init All scripts loaded ScriptManager control UpdatePanel

Sys.Application.Load

A Button inside the UpdatePanel is clicked…

Response message

AJAX Page Processing Events

Server

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Client PageRequestManager

initializeRequest beginRequest

Asynchronous postback request to the server

pageLoading event pageLoaded event

Application load event endRequest event

Response message

AJAX Page Processing Events

Server

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ASP.NET + AJAX

Persisting state on the client using callbacks (e.g., a TreeView control) on the server:

Implement the ICallbackEventHandler interface. Implement the RaiseCallbackEvent method. Implement the GetCallbackResult method.

on the client, provide three scripts: a helper method that performs the actual request to the

server, the client callback function to receive results from the server. A helper function that performs the actual request to the

server generated automatically by ASP.NET when you reference the

GetCallbackEventReference method in server code

See : “Implementing Client Callbacks Programmatically Without Postbacks in ASP.NET Web Pages” for details.

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ASP.NET and AJAX and WCF

Representational State Transfer service (REST) AJAX library wraps asynchronous WCF service endpoints WCF non-SOAP endpoints (i.e., JavaScript Object

Notation or JSON) Try the new Asynchronous WCF HTTP Module/Handler

for long running Requests New in VS 2008 SP1 Releases the IIS worker thread immediately after processing Supports much higher levels of concurrency See Wenlong Dong’s blog for details

ADO.NET Data Services Framework See http://msdn.microsoft.com/en-us/library/cc907912.aspx

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http://blogs.msdn.com/wenlong/archive/2008/08/13/orcas-sp1-improvement-asynchronous-wcf-http-module-handler-for-iis7-for-better-server-scalability.aspx

http://msdn.microsoft.com/en-us/library/cc907912.aspx

WCF code is protocol-independent WCF endpoints:

Addresses Bindings (e.g., WebHttpBinding) Contracts

configure declaratively

ASP.NET + AJAX + WCF

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Service Binding alternatives:

WCF Performance

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Binding Response Time (msecs) Throughput

wsHttpBinding 1300 1200

basicHttpBinding 1150 1800

netTcpBinding 400 5100

netNamedPipeBinding 280 7000

wsHttpBinding

basicH

ttpBinding

netTcpBinding

netNam

edPipeBinding0

2000

4000

6000

8000

Throughput

Source: Resnik, Crane, & Bowen, Essential Windows Communication Foundation, Addison Wesley, 2008. Chapter 4.

See also, “A Performance Comparison of Windows Communication Foundation (WCF) with Existing Distributed Communication Technologies”

Caution: your mileage will vary.

http://www.msnbc.msn.com/id/21134540/vp/27265490#27148560



WCF Scalability

Instancing per-Call servicing is the default mode per-Session servicing (the default)

[ServiceContract(Session = true)]interface IMyContract {...}

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]

class MyService : IMyContract {...}

<netTcpBinding> <binding name="TCPSession"> <reliableSession enabled="true"

inactivityTimeout="00:25:00"/>

</binding></netTcpBinding>

shareable service instances

WCF Scalability

WCF Sessions Explicitly initiated and terminated by the calling

application. Messages are processed in the order in which

they are received. Sessions explicitly group messages into a

conversation. Note: WCF does not create a specific session-

oriented data store

WCF Session-oriented behavior can be handy with Transactions.

WCF Scalability

Singleton service one instance of the service is configured the instance lasts until the Host shuts down the instance can have multiple concurrent threads…[ServiceBehavior( InstanceContextMode=InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple )]

class MySingleton : IMyContract, IDisposable

WCF Scalability

Threading ConcurrencyMode.Multiple

requires locking and synchronization of shared state data

ConcurrencyMode.Reentrant can be used with per-Session callers to limit the

number of concurrent instances

Use serviceThrottling to control concurrency levels<behavior name="Throttled"> <serviceThrottling

maxConcurrentCalls="100" maxConcurrentSessions=“30" maxConcurrentInstances=“20" />

Configure WCF performanceCounters

Mark FriedmanArchitectDeveloper Division

demo

In App.config:

<system.serviceModel>



<diagnostics performanceCounters="All"></diagnostics>

But <diagnostics

performanceCounters=“ServiceOnly"></diagnostics>

is recommended (less overhead)

WCF Diagnostics

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WCF Diagnostics

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WCF Diagnostics

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WCF supports diagnostic tracing & end-to-end tracing scenarios

See “Using Service Trace Viewer for Viewing Correlated Traces and Troubleshooting”

See also, Essential Windows Communication Foundation, Ch. 9.

http://msdn.microsoft.com/en-us/library/aa751795.aspx

http://msdn.microsoft.com/en-us/library/aa751795.aspx

WCF Diagnostics

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WCF Diagnostics

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WCF makes it easy to develop web services

Uri baseAddress = new Uri("http://localhost:8000/HelloService"); string address = "http://localhost:8000/HelloService/MyService"; using (ServiceHost serviceHost = new ServiceHost(typeof(HelloService),

baseAddress)){ serviceHost.AddServiceEndpoint(typeof(IHello), new WebHttpBinding(),

address); serviceHost.Open(); Console.WriteLine("Press <enter> to terminate service"); Console.ReadLine(); serviceHost.Close(); }

AJAX support makes it easy to integrate asynchronous web services into ASP.NET pages


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Use ASP.NET + AJAX + WCF for building Rich Internet Applications Browser Document Object Model (DOM)

Tree of all HTML page elements Need to decompose your web pages into

Synchronous HTML requests for Server-side rendering Asynchronous HTML requests and Javascript

rendering Silverlight controls and WPF XAML elements

Measure: Server-side rendering Download time for all server-side elements Client-side rendering Javascript execution time

ASP.NET programming tools

Use tools like Fiddler

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HTTP performance is constrained by the TCP Protocol TCP ensures in order delivery of all packets

All packets must be Acknowledged Note: full duplex protocol

TCP Session handshaking SYN, SYN-ACK, ACK sequence Negotiates the TCP Window Size Calculates 1st Round Trip Time used by Fast Retransmit logic

TCP Window Upper limit on the amount of data that can be sent to a

Receiver without receiving an Acknowledgement Congestion control (pacing) mechanism Slow Start Full Window used as a congestion signal Round Trip Time, or RTT, determines Timeout interval for

retransmitting unacknowledged, i.e., dropped packets


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Visual Roundtrip Analyzer

demo

Best Practices for Improving Page Load Time


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TCP measures Round Trip Time (RTT) RTT calculated for the initial SYN-ACK sequence

is used a baseline RTT is sampled thereafter and used to drive

reTransmits See also Timestamps Option

It is the Latency, not the Bandwidth that matters.

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VRTA (Visual Round Trip Analyzer)


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Elements of Page Load Time Html CSS Javascript (serialized) XAML Images Audio Video Banner ads (often from 3rd parties) etc.

Page Load parallelism IE7 limited to two parallel sessions IE8 and Chrome support 5 or 6 parallel sessions


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VRTA (Visual Round Trip Analyzer) File details

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VRTA (Visual Round Trip Analyzer) File details

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Best Practices for improving Page Load Time Avoid needless Round Trips to the Server

Use compression!!! Consolidate small image files (image clustering) Set Expiration dates for static content (strong

suggests versioning your web site) Be careful with ETAGs when IIS front-end machines

are clustered Beware of Javascript blocking

Trade off download time against AJAX client functionality

Increase Parallel TCP Ports HTML 1.1 default is two simultaneous TCP Ports Make sure Keep_Alives are turned on


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Best Practices for improving Page Load Time Measure! Measure! Measure! Client-side interaction time measurements

Timestamp Javascript execution time behavior Return response time data to the Server using a Get

Request for a clear gif, passing the response time data in the Query string Using a c.gif for this client-server communication

(aka web beacon) is a common practice in Web analytics

Use an Asynchronous Get Request that doesn’t block!!!


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Documents

Mark Friedman Architect Developer Division Microsoft Corporation