Introduction
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PV178: Programming for .NET Framework
Windows Communication Foundation
Vojtech Forejt, forejt@fi.muni.cz
Martin Osovsky, osovsky@ics.muni.cz
Faculty of Informatics and Institute of Computer Science
Masaryk University
April 20, 2010
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Introduction
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• Applications composed of several processes.
• Processes usually communicate via a network.
• Java RMI, .NET Remoting, Web services...
• Each technology has slightly different purpose.
• The technologies are not compatible.
• Migrating from one technology to another requires a lot of
effort.
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Servi
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• Method of development in which systems provide functionality
as loosely coupled services
• Service - mechanism providing access to one or more
capabilities using a prescribed interface and consistent
constraints and policies
• Each service implements one action (get a weather forecast,
book a hotel room, get latest blog posts,...)
• Services communicate using predefined protocols.
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Basic
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• named and anonymous pipes, mailslots
• rpc, Ipc, ape...
• files
• memory mapped files
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Mess,
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• public, private queues
• implemented via filesystem
• accesible by name e.g. pocitac\jmeno
• methods Send, Peek, Receive
• all have asynchronous versions
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.NET Remoting
• Allows creation of object shared by several applications
• Platform specific
• Similar to Java RMI
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Web
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• Services communicating over standard internet protocols
• Exact behaviour described by standards (SOAP, REST,
WSDL, UDDI,...)
• Messages are mostly passed as X M L files
• Communication between different languages and/or platforms
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3Win
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• Framework for building applications that inter-communicate.
• From .NET 3.0, under development in Mono.
• Follows principles of SOA.
• The underlying architecture may not be hard-coded, can be
changed using config files.
• Namespace System.ServiceModel.
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• Service is a CLR type that exposes a functionality via a set of
methods accessible by remote clients
• Endpoints - Specify the way in which service communicates
with clients
• Address - URI
• Binding - protocols supported
• Contract - functionality supported (methods, types)
Introduction
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Says where the service is available.
Address at which the service awaits incomming messages
<scheme>://<domain>[:port]/[path]
• Examples:
http://example.com/ServiceA
net.msmq://localhost
Every endpoint must have unique address
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Binding
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• Says how the service can be accessed
• Transport protocol - TCP, HTTP, named pipe, M S M Q , . . .
• Message encoding - X M L , binary
• Other protocols - for security, reliability.
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Binding cont.
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• W C F provides classes for most commonly used binding types
• Web services - BasicHttpBinding, WSHttpBinding, ...
• Binary - NetTcpBinding, NetNamedPipeBinding,...
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• Says what the service provides
• Set of operations that the service exposes
• Provided via a class marked with
ServiceContractAttribute and its methods with
OperationContractAttribute.
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• Used by clients to communicate with services
• Hide process of serialization from the client.
• Based on the service contract.
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Channels
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• Facilitate the communication between proxy and service
• Channel stack - transport channel, message encoding channel,
channels for security,...
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• Service is made available through a host process
• Internet Information Services
• Windows Activation Services
• Windows service
• Windows Form
• Console
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Se
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• Used to host services not hosted by IIS
• Type of a service is passed in constructor
• Endpoint are created by AddServiceEndpoint method, or
created from config file.
• Open and Close methods start and stop listening on the
endpoint.
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WCF - Structure
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Client
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Service
Proxy
B Channnel(s) A B C
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message
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Example
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• SimpleWebService
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• The methods described by service contract may need to use
"complex" types.
• Data contract describes how a complex type is serialized.
• DataContractAttribute is applied to the complex type to
be serialized.
• DataMemberAttribute is applied to the serialized members.
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WCF in Visual Studio
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• Rich design time support
• Editing of config files
• Proxy generation
• Service Testing
• Example