Wcf best practices
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This document contains best practices for developing web services and clients using Windows Communication Foundation (WCF). It covers topics such as service and client design patterns, data contracts, service hosting, security, and choosing between SOAP and REST. The document is authored by Brian Noyes, a Microsoft Regional Director and MVP who has written books and training materials on WCF. It is intended to provide guidance to developers on architecting and implementing robust WCF services and clients.
Wcf best practices
- 1. 1Copyright © 2009 Brian Noyes, IDesign Inc Brian Noyes Chief Architect, IDesign www.idesign.net brian.noyes@idesign.net Chief ArchitectChief Architect IDesign Inc. (www.idesign.net)IDesign Inc. (www.idesign.net) Microsoft Regional DirectorMicrosoft Regional Director MVPMVP Microsoft MVPMicrosoft MVP Connected SystemsConnected Systems About Brian PublishingPublishing Developing Applications withDeveloping Applications with Windows Workflow Foundation,Windows Workflow Foundation, LiveLessons training DVD, June 2007LiveLessons training DVD, June 2007 Smart Client Deployment withSmart Client Deployment with ClickOnce, Addison Wesley,ClickOnce, Addison Wesley, January 2007January 2007 Data Binding in Windows Forms 2.0,Data Binding in Windows Forms 2.0, Addison Wesley, January 2006Addison Wesley, January 2006 MSDN Magazine, MSDN Online,MSDN Magazine, MSDN Online, CoDe Magazine, The Server Side .NET,CoDe Magazine, The Server Side .NET, asp.netPRO, Visual Studio Magazineasp.netPRO, Visual Studio Magazine SpeakingSpeaking Microsoft TechEd US, Europe, Malaysia,Microsoft TechEd US, Europe, Malaysia, Visual Studio Connections, DevTeach,Visual Studio Connections, DevTeach, INETA Speakers Bureau, MSDNINETA Speakers Bureau, MSDN WebcastsWebcasts E-mail: brian.noyes@idesign.net Blog: http://briannoyes.net
- 2. 2Copyright © 2009 Brian Noyes, IDesign Inc Agenda Service Best Practices Client Best Practices Data Contracts SOAP vs REST ServiceDefinition Separate contract from implementation Contract (interface) first Define services in a class library, not directly in a host project Layering Separate Service Layer? Instance model Change to Per Call as default Session / Singleton when?
- 3. 3Copyright © 2009 Brian Noyes, IDesign Inc ServiceException Handling For operation specific exceptions Try/catch, throw FaultException<T> Favor using FaultException<T> FaultException can be ambiguous to the client because unhandled exceptions arrive as a FaultException Include FaultContract in service contract definition if you throw FaultExceptions Part of the API you are exposing For global exception handling from services Use an error handler Include exception details in debug builds only ServiceSecurity Intranet services Default Windows Auth may be all you need Possibly Hybrid – Windows Creds / Custom Application Roles Extranet / Internet / Custom security needs Use ASP.NET Membership / Role providers ASP.NET providers Really a standard .NET framework security infrastructure Built in providers for Windows or SQL Server – based credentials / roles Easy to implement custom providers Establish principal on the thread Re-usable across ASP.NET, WCF, WPF & Windows Forms (via Client Application Services)
- 4. 4Copyright © 2009 Brian Noyes, IDesign Inc ServiceHosting Favor WAS Hosting when Server 2008 is an option Multiple protocol support IIS Hosting model and tools Favor IIS for external HTTP only services Better on-box scalability / availability through worker process model Better management tools Favor self-hosting for stateful services, callbacks, .NET Service Bus, debugging Have a console-based debug self-host for development time Can be a Windows Service project that is used for production self-hosting with a mode switch for debugging Consider Dublin hosting in the future SelfHost Code Do not put ServiceHost in a using statement in production code Dispose can throw an exception that masks the real exception thrown from Open call Explicitly call Close in try/catch, log/ deal with exception in catch
- 5. 5Copyright © 2009 Brian Noyes, IDesign Inc Agenda Service Best Practices Client Best Practices Data Contracts SOAP vs REST ClientProxy Classes Favor static proxy class over ChannelFactory Connection caching in the base class in 3.5 Place for encapsulation of common patterns Hand-code or micro-code generate proxy classes for internal services Less bloated code Share service contract and data contracts through libraries Explicit control over config file
- 6. 6Copyright © 2009 Brian Noyes, IDesign Inc ClientProxy Classes Add Service Reference for external services or when you want an async API on the client Clean up config after it destroys it Make sure to add references to data contract libraries before adding the service reference to avoid duplicate definitions Live with the duplicate service contract definition instead of needing to repeatedly clean up the proxy code ClientProxy Management Cache client proxies if frequent calls to avoid session establishment cost If secure / reliable session enabled Have to deal more cautiously with faulted proxies Check proxy state before using Get rid of proxy after exception Don’t put proxies in a using statement Dispose call might throw exception and mask real exception Explicitly close in a try/catch block, and if Close throws an exception, Abort the proxy to ensure resource clean up
- 7. 7Copyright © 2009 Brian Noyes, IDesign Inc ClientException Management All exceptions thrown from a service call derive from CommunicationException FaultException could be wrapped unhandled exception on the client, or explicit error returned from the service FaultException<T> always an explicit error returned from the service Simple approach: Any exception from a proxy call, safe close the proxy Advanced approach: FaultException<T> - proxy is reusable Agenda Service Best Practices Client Best Practices Data Contracts SOAP vs REST
- 8. 8Copyright © 2009 Brian Noyes, IDesign Inc Data Contracts Favor data contracts over serializable types More explicit model, better control over what the client sees Implement IExtensibleDataObject Avoids dropping data that the service / client does not understand Avoid passing complex .NET specific types for interoperable services DataSets and Exception types Data Contracts Avoid XmlSerializer and MessageContracts except for interoperable scenarios and REST services
- 9. 9Copyright © 2009 Brian Noyes, IDesign Inc Agenda Service Best Practices Client Best Practices Data Contracts SOAP vs REST SOAP vs REST Favor SOAP services when you are writing a service that only your code will consume Favor REST services for publicly exposed, data oriented services
- 10. 10Copyright © 2009 Brian Noyes, IDesign Inc Resources IDesign WCF Master Class IDesign WCF Coding Standard – http://www.idesign.net Programming WCF, Juval Lowy, O’Reilly & Associates, 2007 Learning WCF, Michele Leroux Bustamante, O’Reilly & Associates, 2007 Connect Apps with WCF, Brian Noyes, Visual Studio Magazine, Feb 2008, http://visualstudiomagazine.com/articles/2008/02/01/connect-apps-with- wcf.aspx?sc_lang=en Wenlong Dong’s Blog: http://blogs.msdn.com/wenlong/default.aspx E-mail: brian.noyes@idesign.net Blog: http://briannoyes.net