Building WCF Services with WF in .NET 4.0

Ed PintoPMMicrosoft Corporation

Agenda

Motivation WF 4.0 Basics WCF and WF

Async I/O Error Handling Correlation

Hosting and Monitoring Other WCF 4.0 Improvements

Challenges

Work is increasingly distributed Coordination code creates complexity

Coordinating messages with application state Coordinating calls to a database or another

service (Async I/O) Coordinating rainy day scenarios

Management and tracking of distributed work is difficult

Host“Dublin”(IIS/WAS + App Server Extensions)

Microsoft ® .NET Workflow Service <your own>.exe

WF Runtime

What is WF?

WF programs coordinate work with minimal ceremony

Activities Runtime Tooling

Tooling

VS Designer VS Debugger Rehosted Designer

Workflow

Activity Library

Activities are the primitive abstraction for behaviorActivities are composable with other ActivitiesActivities have user-defined Variables for data storageActivities bind Arguments to in-scope VariablesActivities define Arguments to declare the type of data that can flow into or out of an ActivityFlow Chart

Parallel

Sequence

Activities

Send Message

Delay Receive Message

Generate Order

InArgument<TimeSpan>

OutArgument<Order>

InArgument<Message>

OutArgument<Message>

Process Order

Send Report

Variables

Variables

Variables

Instances

Management Endpoint

BehaviorsPersistence

Tracking

ServiceHostBase

…Tracking

Workflow Service Host

Activity Library

SendMessage

WCF and WF

ReceiveMessage

...

Instances

Management Endpoint

BehaviorsPersistence

Tracking

ServiceHostBase

…Tracking

Workflow Service Host

Activity Library

SendMessage

WCF and WF

ReceiveMessage

...

Coordinating Asynchronous Concurrency//Simple to author and maintain, performs poorly[OperationContract]public Picture GetPicture(string name){ //blocking I/O byte[] bytes = mediaService.GetMedia(name); return new Picture { Bytes = bytes, Name = name};}

//Performs well, difficult to author and maintain[OperationContract(AsyncPattern = true)]IAsyncResult public BeginGetPicture(string name, AsyncCallback callback, object state){ return new PictureAsyncResult(name, callback, state);}

Picture EndGetPicture(IAsyncResult result){ return PictureAsyncResult.End(result);}

Coordinating Asynchronous Concurrency//Simple to author and maintain, calls are sequential[OperationContract]public Picture GetPicture(string name){ //blocking I/O byte[] bytes = mediaService.GetMedia(name); //blocking I/O PictureInfo info = pictuerInfoService.GetPictureInfo(name); return new Picture { Bytes = bytes, PictureInfo = info };}

//calls can be made in parallel, difficult to author and maintain[OperationContract(AsyncPattern = true)]IAsyncResult public BeginGetPicture(string name, AsyncCallback callback, object state){ return new BiggerPictureAsyncResult(name, callback, state);}

Picture EndGetPicture(IAsyncResult result){ return BiggerPictureAsyncResult.End(result);}

Coordinating Asynchronous Concurrency

Workflow Runtime

Client Operation

I/OScheduler

Parallel

GetMedia GetPictureInfo

Sequence

GetMedia

Other Activities

Coordinating Asynchronous Work

GetMedia

Client

PictureService

MediaService

GetPictureInfo

GetPicture

PictureInfo

Service

Coordinating Asynchronous Concurrency

demo

Try Catch Finally

Exception Handling Logic

Process Message

Variables

Sequence

Flow In Transaction Scope

Variables

Receive Message

Coordinating Error Handling

Exceptions Transactions Compensation /

Cancellation

CompensableActivity

Compensation Logic

Body

Variables

Do X

Compensate X

Correlation

Submit TaskJobId = 123

Task Complete JobId = 123

3. Send

4. Receive

1. Start Job 123

6. Job 123 Complete

Application

Application State

2. Store Job 123

5. Lookup Job 123

JobId 789JobId 456

JobId 123

Correlation

Correlation QueryChannels

Context

SendMessage/ReceiveMessage+ CorrelationHandle

Instance Store

Content (poid=123)

Workflow

Correlation

Submit Task

Task Complete

2. Send

4. Receive

1. Start Job 123

6. Job 123 Complete

CorrelationHandle

Query Results

JobId=123

Query Results

JobId=123

Application State

JobId 789JobId 456

JobId 123

Correlation Query

JobId = 123

Correlation Query

JobId = 123

SendMessage

ReceiveMessage

3. Store workflow with query results

5. Lookup workflow using query results

PictureInfo

Service

Correlation

GetMedia

Client

PictureService

MediaService

GetPictureInfo

GetPicture

Picture

Context Based Correlation

Context Based Correlation

Content Based Correlation

Media

PictureInfo

Message Correlation

demo

[OperationContract]public void SubmitOrder(Order order){ // your code here}

Workflow Service Host

Hosting and Monitoring

Persistence

Tracking

IIS/WAS Site/Service Configuration

Tracking

IIS Manager • Management• Control• Enumeration• Tracking

Management Endpoint

Tracking

Instances

WCF + WF + "Dublin"

PowerShellManagement APIs

Hosting and Monitoring

demo

When Should I Write WCF Services using Workflow?

Consider Workflow Services if your service: Calls a database, calls another service, or uses

the file system Coordinates parallel work Enforces ordering between messages Coordinates messages with application state Is long running Requires rich tracking information

Other WCF 4.0 Improvements

REST toolkit Discovery Local Services New Channels: UDP, Http Polling Duplex Standards: SOAP over UDP, BP 1.2 Standard Endpoints Durable Duplex Simplified ConfigAnd much much more….

Conclusion

WF and WCF push complex coordination to the framework Async I/O Error Handling Correlation

WF and WCF make service state queryable “Dublin” provides enterprise

Persistence Tracking Management More …

Resources

Breakout Sessions BB18 - "Dublin": Hosting and Managing Workflows

and Services TL38 - WCF: Zen of Performance and Scale TL35 - WCF: Developing RESTful Services TL17 - WF 4.0: A First Look TL21 - WF 4.0: Extending with Custom Activities TL36 - Microsoft .NET Framework: Declarative

Programming Using XAML BB27 - .NET Services: Orchestrating Services and

Business Processes Using Cloud-Based Workflow http://msdn.microsoft.com/wcf/future/ http://msdn.microsoft.com/wf/future/ Questions to wfpdc@microsoft.com

Evals & Recordings

Please fill

out your

evaluation for

this session at:

This session will be available as a recording at:

www.microsoftpdc.com

Please use the microphones provided

Q&A

© 2008 Microsoft Corporation. All rights reserved. Microsoft, Windows, Windows Vista and other product names are or may be registered trademarks and/or trademarks in the U.S. and/or other countries.The information herein is for informational purposes only and represents the current view of Microsoft Corporation as of the date of this presentation. Because Microsoft must respond to changing market

conditions, it should not be interpreted to be a commitment on the part of Microsoft, and Microsoft cannot guarantee the accuracy of any information provided after the date of this presentation. MICROSOFT MAKES NO WARRANTIES, EXPRESS, IMPLIED OR STATUTORY, AS TO THE INFORMATION IN THIS PRESENTATION.

Correlation

Correlation QueryChannels

Cookies Context

SendMessage/ReceiveMessage+ CorrelationHandle

Instance Store

Body Content (poid=123)

InstancesInstances

Management Endpoint

Behaviors

Persistence

Tracking

IIS/WASSite/Service

Configuration

Service Host[OperationContract]public void SubmitOrder(Order order){ // your code here} …

Tools Trace Viewer

Test Client

Tracking

Designer Debugger

IIS Manager • Management• Control• Enumeration• Tracking

Management Endpoint

Metadata

Tracking

…

WCFWCF + WFWCF + WF + "Dublin"

Workflow Service HostActivity Library

SendMessage

ReceiveMessage

…

Channels (HTTP, TCP, NamedPipes, …)

Config Editor

PowerShellManagement APIs

WCF 4.0 Improvements

Rest toolkit Standards:

SOAP over UDP, WS-Discovery, WS-BA, WS-RSP, BP 1.2

Local Services New Channels

UDP, Polling Http Duplex Discoverable services Programming model simplifications

Standard Endpoints Config

…

Host

WF Runtime

What is WF?

WF programs coordinate work with minimal ceremony

Activities Runtime Tooling

ToolingVS

DesignerVS

DebuggerRehosted Designer

WorkflowActivity Library

Correlation

Application

Submit OrderPOId = 123

Update OrderPOId = 123

POId 789POId 456

POId 123

Application State

1. Receive

2. Store PO 123

3. Receive

4. Lookup PO 123

5. Store PO 123

Coordinating Asynchronous Work

Xaml GetMedia(Name)Client

PictureService

MediaService

PictureInfo

Service

PictureInfo GetPictureInfo(Name)

Picture GetPicture(Name)