WCF Intro Scott Reed Owner - Brain Hz Software Instructor – DevelopMentor

Agenda Why WCF? Architecture Programmatic client and service Moving to configuration Sharing contracts Summary

Before WCF TechnologyProsCons SocketsFlexibleCode everything RPCImperative request/replySimplistic, synchronous DCOMTrxs, SecurityComplex, hard to debug/maintain.NET RemotingEasy, configurable, extensible No interoperability ASMX Web ServicesEasy, interoperableSimplistic, Security=SSL only WSE 2.0/3.0Added message securityNot as easy, Verbose, still lacking MSMQAsync, solves availabilityExplicit message passing Clearly not an enabling technology, instead it is unifying

WCF Design goal Design goal: – To be the best way to get any two pieces of software to communicate under any circumstances To achieve this had to abstract communication – Services are programs that exchange messages – Lower layer sends messages through channels

Messages Packaged data Abstraction of a SOAP message – Xml InfoSet not actually XML Created using factory method – Message.CreateMessage

Channels Channel transmit those messages Channels together form a stack Protocol channels can be layered on top – Provide services like reliability and security Encoder changes Message to byte[] Transport channel actually sends the bytes

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Programming in the Channel Layer Explicit message passing like in sockets or MSMQ – What happened to easy? void ChannelListen() { IChannelListener listener = GetListener(); listener.Open(); while (listener.WaitForChannel()) { IReplyChannel channel = listener.AcceptChannel(); channel.Open(); RequestContext request = channel.ReceiveRequest(); Message reply = HandleMessage(request.RequestMessage); request.Reply(reply); request.Close(); channel.Close(); } void ChannelListen() { IChannelListener listener = GetListener(); listener.Open(); while (listener.WaitForChannel()) { IReplyChannel channel = listener.AcceptChannel(); channel.Open(); RequestContext request = channel.ReceiveRequest(); Message reply = HandleMessage(request.RequestMessage); request.Reply(reply); request.Close(); channel.Close(); }

Service Model Layer Sits on top of Channel Layer and hides it Allows method invocation of strongly typed parameters Uses serialization to translate objects into messages

The Big Picture protocol encoder transport protocol encoder transport serializer proxy dispatcher service object Service Model Layer Channel Layer

Endpoint Clients talk to endpoints, and services expose endpoints Address Binding Contract

BCA BCA BCA BCA BCA ClientService

WCF in all its glory Business Partner Customer wsHttpBinding (feature rich) basicHttpBinding (compatibility) netTcpBinding (performance) netMsmqBinding (batch processing) netNamedPipeBinding (local, fast) Browser webHttpBinding (AJAX, JSON…)

Hosting Need something to listen for incoming connections (a host) WCF is host independent (by default) Self host (Console, NT Service, Forms/WPF App) – Use the ServiceHost class (Open and Close) IIS/WAS hosted – Use a.svc file (just like ASMX) WCF provided host for testing * – WcfServiceHost

Step by step Define the contract Implement the contract Host the service Expose endpoints Optionally expose metadata

Demo Writing a programmatic client and a service

Configuration Why do it in config? – So you don’t have to recompile Everything you do in code can be done in config (almost)

Demo (revisited) Changing to a config file

Sharing contracts Both the client and the service need to know the types and methods listed in the contract There are two ways to accomplish this: – Share types (ala Remoting) – Share schema (ala ASMX)

Demo (revisited again) Exposing metadata (base and explicit) Generating a proxy

Summary WCF unifies communications technology Architected in two layers: – Channel layer and Service Model layer Endpoints are ABCs Two ways to share contract (type and schema)