Connecting Applications With Wcf

7/28/2019 Connecting Applications With Wcf

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12007 Brian Noyes, IDesign Inc All Rights Reserved

2008 Brian Noyes, IDesign Inc. All rights reserved

Brian Noyes

www.idesign.net

Connecting Applications with Windows

Communication Foundation

About Brian

n Chief Architect, IDesign Inc. (www.idesign.net)

n Microsoft Regional Director / MVP

n Publishing

l Developing Applications with Windows Workflow Foundation,LiveLessons training DVD, June 2007.

l Smart Client Deployment with ClickOnce, Addison Wesley, January 2007

l Data Binding in Windows Forms 2.0, Addison Wesley, January 2006

l MSDN Magazine, MSDN Online, CoDe Magazine, The Server Side .NET,asp.netPRO, Visual Studio Magazine

n Speaking

l Microsoft TechEd US, Europe, Malaysia, Visual Studio Connections,DevTeach, INETA Speakers Bureau, MSDN Webcasts

n Participates in Microsoft Design Reviews

n E-mail:[email protected]

n Blog: http://briannoyes.net
http://www.idesign.net/http://www.idesign.net/mailto:[email protected]://briannoyes.net/http://briannoyes.net/mailto:[email protected]://www.idesign.net/http://www.idesign.net/


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Agenda

n Connected Systems Concerns

n WCF Overview

n WCF ABCs and Es

n Defining Services

n Connecting Clients

n Passing Data

n Advanced Capabilities

Connected Systems in a SO World

n Need to connect clients to back-end services

n Need to connect services to other services

n Need to be decoupled from the specific service technology / calling patterns

n Need support for distributed system capabilities:

l Service hosting

l Instance management

l Reliability

l Async communications

l Transactions

l Security


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SOA Tenets

n Service boundaries are explicit

n Services are described by policy

n Services expose contract and schema, not types

n Services are autonomous

What if Im not doing SOA?

n If your application is composed of more than one process, you

still need a remoting technology

n WCF is the best available remoting technology even if you are

just doing client/server, point-to-point communication


4/20


Agenda


n WCF Overview

n WCF ABCs and Es

n Defining Services


n Passing Data


WCF Overview

n Framework for connecting distributed applications

n Part of .NET 3.0 and later

n Enables building SOA applications

n Implements WS-* standards

n Single API that supports the capabilities of:

l .NET Remoting

l ASP.NET Web Services

l Enterprise Services (COM+)

l MSMQ


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WCF Overview

n Messaging subsystem at its core

l SOAP messages

Does not necessarily mean XML/Text!

n Interoperability with:

l Enterprise Services

l ASMX / Web Services 1.0 services

l Any WS-* compliant web service

l MSMQ applications

WCF Value Proposition

n Simplicity

l On par with other remoting technologies if you just need simple remote calls

l Incrementally more complex as you start to take advantage of more complex

features

Features which the other technologies may not have

n Flexibility

l You can change your mind about wire level communication protocols, security

model, and many other facets without changing your source code

n Maintainability

l One API for all forms of remote communication, dont need to learn multiple

technology stacks

n Power

l All the capabilities of other remoting APIs rolled into one

l Interoperability and SOA enabled in ways the other technologies never considered


6/20


Agenda


n WCF Overview

n WCF ABCs and Es

n Defining Services


n Passing Data


WCF ABCs and Es

n Clients and services communicate through Endpoints

ClientClient ServiceService

MessageMessageEndpointEndpoint EndpointEndpoint

EndpointEndpoint


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WCF ABCs and Es

n Enpoints are composed of Address, Binding, Contract

ClientClient ServiceService

MessageMessageAABBCC AA BB CC

AA BB CC

AddressAddress BindingBinding ContractContract

(Where)(Where) (How)(How) (What)(What)

WCF Addresses

n Location of the service

n URL

l Protocol

l Server/domain

l Port

l Service URI (optional)

n Examples:

l http://myappserver:2112/

l http://my.service.domain.com/SomeServiceURI

l net.tcp://myappserver:2112/SomeServiceURI
http://my.service.domain.com/SomeServiceURIhttp://my.service.domain.com/SomeServiceURI


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WCF Bindings

n The brains of the communications

n Encapsulates what happens on the wire

l Wire level protocol

l Communication patterns

l Message format

l Security

l Transactions

l

Reliabilityn Can all be extracted out of code and put in config

WCF Bindings

n WCF defines several standard bindings

l Basic

l TCP

l Peer TCP

l Named Pipe

l WS

n Many variation bindings

l Context, Dual, Federation, etc

n Can customize standard bindings

n Can define custom bindings


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WCF Contracts

n Service Contracts

l Operations exposed by the service

n Data Contracts

l What data is passed through the service operations

n Message Contracts

l What the message looks like when serialized

n Fault Contracts

l

What error messages look like

Agenda


n WCF Overview

n WCF ABCs and Es

n Defining Services


n Passing Data



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Defining Services

n Define a Service Contract

l .NET interface

l [ServiceContract] attribute on the type

l [OperationContract] attribute on the operations (methods)

Defining Services

n Implement a service types

l Implements service contract interface

l Does not require any WCF specifics for basic communication

l Add [ServiceBehavior] attribute with properties for special

communication patterns

Timeouts, instancing, concurrency, transactions


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Agenda


n WCF Overview

n WCF ABCs and Es

n Defining Services


n Passing Data


Connecting Clients

n Need a WCF proxy on the client

l Generate

svcutil.exe

Add Service Reference in VS

Code gen (snippets, CodeRush, CodeSmith)

l Dynamically create

ChannelFactory class

n Proxy exposes service contract methods

n Create instance of proxy, call methods


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Agenda


n WCF Overview

n WCF ABCs and Es

n Defining Services


n Passing Data


Passing Data

n Based on Data Contracts

n .NET primitives work out-of-box

l Serializable

n Any serializable type by default

n XmlSerializable types if you change the formatter

n Best practice:

l Define data contracts for custom types used in the service

contract [DataContract] attribute on the entity type

[DataMember] attribute on the properties you want to be contained in

the data transfered


13/20


Agenda


n WCF Overview

n WCF ABCs and Es

n Defining Services


n Passing Data


Advanced Capabilities

n Asynchronous calls

n Callbacks

n Sessions

n Security

n Reliability

n Queuing

n Transactions

n Peer to Peer


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Asynchronous calls

n Service calls can:

l Take a long time

l Be one-way

l Call back into client

l Be re-entrant

n Need to make calls asynchronously

n Handle completion / error handling

n Display results in UI

l Completion events/callbacks on background thread

Asynchronous Calls

n Manual Async Calls

l Delegate based

l BeginXXX/EndXXX method variants

Svcutil /a switch

OperationContract.AsyncPattern = true

l Register callback method

l Gets called on background thread, must marshal results

yourself to UI thread (ISynchronizeInvoke)


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Callbacks

n Service can call client

l Events

n Need to register client callback contract on service

l ServiceContract.CallbackContract

n Need to obtain callback channel instance in service

l OperationContext.GetCallbackChannel

n Callbacks happen asynchronously from client perspective

Sessions

n Often service calls are related to one another

l Start Order

l Add Order Items

l Submit Order

n Individual service calls are just messages

l Underlying protocol does not support sessions

n Need to relate multiple messages together

n Sessions are maintained through shared service instances on service side

n

NOTE: Session is the default instancing moden NOTE: Sessions are BAD for scalability

n NOTE: Sessions get messy with transactions / web farms / etc.


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Security

n Three kinds: Transport, Message, Mixed

n Must match the requirements of the service

n Credentials:

l Windows

l X.509

l Username/password

l Cardspace

n Message integrity / confidentiality

l SSL

l WS-Security

n Authorization

l .NET Role-based securityl PrincipalPermission / IsInRole

Reliability

n Reliable transports

l TCP

l IPC

n WCF reliability deals with message reliability

n Enables order delivery assurance

n Reliability is controlled in the binding

l Supported/not supported

l Enabled/disabled


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Reliability

n Reliability not supported

l Basic binding

l Peer TCP binding

l MSMQ/MSMQ integration binding

n Reliability always enabled

l WS dual binding

n Reliability disabled by default but can be enabled

l

TCP bindingl WS binding

n Reliable by definition while not using WCF reliability

l Named pipes

Queuing

n Message queuing technologies allow communications that are:

l Asynchronous

l One way

l Buffered

l Disconnected

n Great for submit types of operations where you dont need

immediate feedback in the client of service side processing


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Queued Calls

ClientProxy

DispatcherMSMQ

Queue

MSMQ

Message

Service

MSMQ

Channel

Listener

Dispatcher Service

Client Initiated Transactions

n Indigo transactions built on top of System.Transactions + WS-*

n Initiate a transaction in client code

n Transaction is flowed to all services called that support transactions

using (TransactionScope scope =new TransactionScope())

{// Call Service1 transaction flowed to service1// Call Service2 transaction flowed to service2scope.Complete();

} // All commit or all rollback


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Enabling Transactions

n Transactions do not flow by default

n Requirements:

l Enclose service calls in transaction scope on client

l transactionFlow = true on binding

l [TransactionFlow] attribute on service contract methods

Optional specify transaction scoping options

l OperationBehavior attribute on service methods

TransactionFlowRequired = true

TransactionAutoComplete = true

Peer-to-Peer Communications

n No true multicast in V1

n Each client is a also service

n Must call every other (interested) client directly

n Can simulate with duplex channels

n Can use PeerChannel


20/20

202007 Brian Noyes IDesign Inc All Rights Reserved

Resources

n Programming WCF, Juval Lowy, OReilly & Associates.

n Learning WCF, Michele Leroux Bustamante, OReilly &Associates.

n IDesign WCF Master Class, www.idesign.net.

n IDesign articles:http://www.idesign.net/idesign/DesktopDefault.aspx?tabindex=-1&tabid=9

n WCF Dev Site: http://msdn.microsoft.com/wcf

E-mail: [email protected]

Blog: http://briannoyes.net
http://www.idesign.net/http://www.idesign.net/idesign/DesktopDefault.aspx?tabindex=http://msdn.microsoft.com/wcfmailto:[email protected]://briannoyes.net/http://briannoyes.net/mailto:[email protected]://msdn.microsoft.com/wcfhttp://www.idesign.net/idesign/DesktopDefault.aspx?tabindex=http://www.idesign.net/

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