Best practices for versioning your services with WCF? - wcf

I'm starting to work with my model almost exclusively in WCF and wanted to get some practical approaches to versioning these services over time. Can anyone point me in the right direction?

There is a good writeup on Craig McMurtry's WebLog. Its from 2006, but most of it is still relevant.
As well as a decision tree to walk through the choices, he shows how to implement those changes using Windows Communication Foundation

See "Versioning WCF Services: Part I" and "Versioning WCF Services: Part II".
See also:
WCF Backwards Compatibility and Versioning Strategies – Part 1
WCF Backward Compatibility and Versioning Strategies – Part 2
WCF Backward Compatibility and Versioning Strategies – Part 3

While not an instant answer for you, I found the book Learning WCF very useful; in it there's a small section on versioning (which is similar to Craig McMurtry's advice posted by Espo). If you're looking for a general intro book, it's very good. Her website has lots of good stuff too: Das Blonde
Edit:
No sure why her site isn't responding; it's been a while since I've visited, so maybe she shut it down. No sure.

Related

Windows Communication Foundation (WCF) for beginners

I need to learn WCF for my project as I am building a client-server application under Windows. What's the best place to start. I've googled for tutorials and books but I couldn't find something suitable for starters. I would prefer a book.
As for resoures: there's the MSDN WCF Developer Center which has everything from beginner's tutorials to articles and sample code.
Also, check out the screen cast library up on MSDN for some really useful, 10-15 minute chunks of information on just about any topic related to WCF you might be interested in.
Look at PluralSight videos may be its easy way for you to start. Some of the videos are on MSDN for free.
Find book for yourself. For example this one could be easy to understand for beginner.
Look at WCF samples. Some samples can help you in learning.
If you prefer a good book, check out Programming WCF Services, 3rd Edition by Juval Lowy.
Other WCF book recommendations are listed in this question.

Conceptual overview of WCF security model?

I'm working with WCF at the moment and attempting to implement a custom security model based around an API key and signature (similar to how Facebook/Flickr/OAuth etc. work).
There are a while bunch of classes like ServiceAuthorizationManager, SecurityToken, SecurityTokenValidator, IAuthorizationPolicy and so on, but I can't seem to find any documentation about how these work together or what the conceptual security model is for WCF.
I'm really looking for something that details how these classes fit and work together, so I can understand where to extract credentials, where to validate they are correct, where to decide what level of access to give them and so on. If there is a book I can buy about this stuff it would be even better, as all the WCF books I have found skip over all this stuff entirely.
Is there any documentation out there?
Take a look at Juval Lowy's excellent "Programming WCF Services," 2nd Edition:
Here's the link to Amazon's page on it.
Chapter 10 is completely devoted to security.
Microsoft has released a WCF Security Guide - a free(!) eBook. You can find it here.
That's an awful lot of information to wade through. Good luck!

New architecture concepts

I posted this community wiki in the hopes of creating a thread of expertise. My question is thus ... "Where do the experts go to learn about the newest coding techniques?".
I'm basically looking for the leading/bleeding edge of architecture, design, development and theory.
I know conferences and trade shows are probably the best venues to see the latest and greatest, but for those on a limited budget (of both time and money) such as myself, I'm looking for websites that I can read in the evenings that will keep me current on what's new in the world.
I program mostly in C# but the websites need not be geared towards C#.
Blogs
Martin Fowler, the best starting point I think. (http://martinfowler.com/)
articles like "Consumer-Driven Contracts: A Service Evolution Pattern", "Mocks Aren't Stubs", "Inversion of Control Containers and the Dependency Injection pattern" (http://martinfowler.com/articles.html)
David Hayden (http://www.davidhayden.com/)
Reflective Perspective, a good daily feed (http://blog.cwa.me.uk/tags/morning-brew/)
Ayende (http://ayende.com/Blog/)
Eric Lippert - Works on the language. Sometimes read about new C# features before they're announced elsewhere.
Scott Hanselman
Journals
The Architecture Journal (http://msdn.microsoft.com/en-us/architecture/bb410935.aspx) And what's a great option - you can order free, paper based copies!
MSDN Magazine (http://msdn.microsoft.com/en-us/magazine/default.aspx)
Community
Codeproject.com, short and large articles
pnpguidance.com, tutorials, blogs and articles
Real applications and devteams
pattern&practices home: http://msdn.microsoft.com/en-us/practices/default.aspx, and P&P products
SCSF, the Smart Client Software Factory home. Learn about desktop enterprise systems. (http://msdn.microsoft.com/en-us/library/aa480482.aspx)
WCSF, the Web Client Software Factory home. Learn about busines(process) oriented web architecures. (http://msdn.microsoft.com/en-us/library/bb264518.aspx)
Enterprise Library
For free - I would recommend MSDN, particularly keep an eye on the C# and .NET technology pages. Lots of blogs, and nearly every announcements about what's up and coming is put there.
Serverside.net
The ondemand(previously recorded) webcasts from Microsoft are normally really good, but it's a painful number of clicks to actually get to the point where you can download the file, and sometimes you find that it is not available.
Also sometimes you can find a .NET User Group locally that will have speakers/sessions occasionally. These are also great ways to network and find out what kind of work is going on in your area.
Books, books, books! Good books are written by subject matter expects, involve input from many sources, are peer reviewed, well structured and go orders of magnitude deeper than trade shows, and most online material. When you buy a book, you get the experience of an expert for a very reasonable price.
NDepend documentation comes with two white books and also online blog posts and articles concerning the architecture for large .NET application:
Partitioning code base through .NET assemblies and Visual Studio projects (8 pages)
Defining .NET Components with Namespaces (7 pages)
Control Components Dependencies to gain Clean Architecture
Re-factoring, Re-Structuring and the cost of Levelizing
Evolutionary Design and Acyclic componentization
Layering, the Level metric and the Discourse of Method
Fighting Fabricated Complexity
I never get to go to PDC, but I do love to watch the videos.
As a previous post mentioned the MS PDC videos are on online. Same with Mix which has good MS Web development related content. Also, for general MS videos there is Channel 9, it's not all technical content, but it's worth searching if you are looking for something in particular.
Someone already mentioned blogs, here are a few more:
Scott Hansleman - lots of stuff on there, a lot of ASP, MVC stuff.
Phil Haack - another good MVC guy.
Rob Connery - again a lot of focus on MVC.
ScottGu - according to his blog he "builds a few products for Microsoft", which has to be the understatment of the year - he is in charge of ASP, IIS, SIlverlight and much more besides at MS.
Check out Sharp Architecture, it's very promising.
I've collected several RSS feeds that I regularly to stay up-to-date on .NET and Agile. If you like I can share the list with you. It contains most of the stuff already mentioned here.

Understanding WCF

Could anyone point me to a resource that explains WCF with pictures and simple code snippets. I am tired of googling and finding the same "ABC" articles in all search results.
WCF is a very complex technology that in my opinion is very poorly documented. It is incredibly easy to get up and running with, but the performance tuning to run a large scale app can be incredibly complicated and a lot of trial and error. One day everything is working fine and then you find out that only a single Channel is kept waiting for a new connection and that there is a config setting that you need to adjust on a custom binding to allow more channels to be waiting so that calls don't fail inbetween when a channel is used and the next channel is spun up.
In general Nicholas Allen's blog is a gold mine of information. However Windbg has been my best friend in trying to explain some very bizarre behavior coming from WCF.
Here's a really simple example. It's specific to CE/Mobile devices, but the concept is no different PC to PC.
I found the following two books to be really good for getting up to speed on WCF:
Programming WCF Services (Lowy - O'Reilly)
Pro WCF (Peiris, Mulder - Apress)
They both start with more of a conceptual description of WCF, so you understand the concepts and terms. This is really useful, because it allows you to narrow any google searches to more specific concepts.
And this is an article that breaks down understanding WCF and why it was developed in a simple, bulleted list.

Does WCF raise the bar or just the complexity level? [closed]

Closed. This question is opinion-based. It is not currently accepting answers.
Want to improve this question? Update the question so it can be answered with facts and citations by editing this post.
Closed 3 years ago.
Improve this question
I understand the value of the three-part service/host/client model offered by WCF. But is it just me or does it seem like WCF took something pretty direct and straightforward (the ASMX model) and made a mess out of it?
Is there an alternative to using SvcUtil's command line step back in time to generate the proxy? With ASMX services a test harness was automatically provided; is there a good alternative today with WCF?
I appreciate that the WS* stuff is more tightly integrated with WCF and hope to find some payoff for WCF there, but geeze, otherwise I'm perplexed.
Also, the state of books available for WCF is abysmal at best. Juval Lowy, a superb author, has written a good O'Reilly reference book "Programming WCF Services" but it doesn't do that much (for me anyway) for learning now to use WCF. That book's precursor (and a little better organized, but not much, as a tutorial) is Michele Leroux Bustamante's Learning WCF. It has good spots but is outdated in place and its corresponding Web site is gone.
Do you have good WCF learning references besides just continuing to Google the bejebus out of things?
Okay, here we go. First, Michele Leroux Bustamante's book has been updated for VS2008. The website for the book is not gone. It's up right now, and it has tons of great WCF info. On that website she provides updated code compatible with VS2008 for all the examples in her book. If you order from Amazon, you will get the reprint which is updated.
WCF is not only a replacement for ASMX. Sure it can (and does quite well) replace ASMX, but the real benefit is that it allows your services to be self-hosted. Most of the functionality from WSE has been baked in from the start. The framework is highly configurable, and the ability to serve multiple endpoints over multiple protocols is amazing, IMO.
While you can still generate proxy classes from the "Add Service Reference" option, it's not necessary. All you really have to do is copy your ServiceContract interface and tell your code where to find the endpoint for the service, and that's it. You can call methods from the service with very little code. Using this method, you have complete control over the implementation. Regardless of the method you choose to generate a proxy class, Michele shows both and uses both in her excellent series of webcasts on the subject.
Michele has tons of great material out there, and I recommend you check out her website(s). Here's some links that were incredibly helpful for me as I was learning WCF. I hope that you'll come to realize how strong WCF really is, and how easy it is to implement. The learning curve is a little bit steep, but the rewards for your time investment are well worth it:
Michele's webcasts: http://www.dasblonde.net/2007/06/24/WCFWebcastSeries.aspx
Michele's book website (alive and updated for VS2008): http://www.thatindigogirl.com/
I recommend you watch at least 1 of Michele's webcasts. She is a very effective presenter, and she's obviously incredibly knowledgeable when it comes to WCF. She does a great job of demystifying the inner workings of WCF from the ground up.
I typically use Google to find my WCF answers and commonly find myself on the following blogs:
Blogs with valuable WCF articles
http://blogs.msdn.com/drnick/default.aspx
http://blogs.msdn.com/wenlong/default.aspx
http://blogs.thinktecture.com/buddhike/
http://www.dasblonde.net/default.aspx
Other valuable articles I've found
http://blogs.conchango.com/pauloreichert/archive/2007/02/22/WCF-Reliable-Sessions-Puzzle.aspx
http://blogs.msdn.com/salvapatuel/archive/2007/04/25/why-using-is-bad-for-your-wcf-service-host.aspx
I'm having a hardtime to see when I should or would use WCF. Why? Because I put productivity and simplicity on top of my list. Why was the ASMX model so succesful, because it worked, and you get it to work fast. And with VS 2005 and .NET 2.0 wsdl.exe was spitting out pretty nice and compliant services.
In real life you should have very few communication protocols in your architecture. This keeps it simple an maintainable. If you need to acces to legacy systems, write specific adapters for them so they can play along in the nice shiny and beautiful SOA world.
WCF is much more powerful than ASMX and it extends it in several ways. ASMX is limited to only HTTP, whereas WCF can use several protocols for its communication (granted, HTTP is still the way most people will use it, at least for services that need to be interoperable). WCF is also easier to extend. At least, it is possible to extend it in ways that ASMX cannot be extended. "Easy" may be stretching it. =)
The added functionality offered by WCF far outweighs the complexity it adds, in my opinion. I also feel that the programming model is easier. DataContracts are much nicer than having to serialize using XML serialization with public properties for everything, for example. It's also much more declarative in nature, which is also nice.
Wait.... did you ever use .NET Remoting, cause thats the real thing its replacing. .NET Remoting is pretty complicated itself. I find WCF easier and better laid out.
I don't see it mentioned often enough, but you can still implement fairly simple services with WCF, very similar to ASMX services. For example:
[ServiceContract]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class SimpleService
{
[OperationContract]
public string HelloWorld()
{
return "Hello World";
}
}
You still have to register the end point in your web.config, but that's not so bad.
Eliminating the verbosity of the separated data, service, and operation contracts goes a long way toward making WCF more manageable for me.
VS2008 includes the "Add Service Reference" context menu item which will create the proxy for you behind the scenes.
As was mentioned previously, WCF is not intended solely as a replacement for the ASMX web service types, but to provide a consistent, secure and scalable methodology for all interoperable services, whether it is over HTTP, tcp, named pipes or MSMQ transports.
I will confess that I do have other issues with WCF (e.g. re-writing method signatures when exposing a service over basicHTTP - see here, but overall I think it is a definite imrovement
If you're using VS2008 and create a WCF project then you automatically get a test harness when you hit run/debug and you can add a reference without having to use svcutil.
My initial thoughts of WCF were exactly the same! Here are some solutions:
Program your own proxy/client layer utilising generics (see classes ClientBase, Binding). I've found this easy to get working, but hard to perfect.
Use a third party implementation of 1 (SoftwareIsHardwork is my current favourite)
WCF is a replacement for all earlier web service technologies from Microsoft. It also does a lot more than what is traditionally considered as "web services".
WCF "web services" are part of a much broader spectrum of remote communication enabled through WCF. You will get a much higher degree of flexibility and portability doing things in WCF than through traditional ASMX because WCF is designed, from the ground up, to summarize all of the different distributed programming infrastructures offered by Microsoft. An endpoint in WCF can be communicated with just as easily over SOAP/XML as it can over TCP/binary and to change this medium is simply a configuration file mod. In theory, this reduces the amount of new code needed when porting or changing business needs, targets, etc.
ASMX is older than WCF, and anything ASMX can do so can WCF (and more). Basically you can see WCF as trying to logically group together all the different ways of getting two apps to communicate in the world of Microsoft; ASMX was just one of these many ways and so is now grouped under the WCF umbrella of capabilities.
Web Services can be accessed only over HTTP & it works in stateless environment, where WCF is flexible because its services can be hosted in different types of applications. Common scenarios for hosting WCF services are IIS,WAS, Self-hosting, Managed Windows Service.
The major difference is that Web Services Use XmlSerializer. But WCF Uses DataContractSerializer which is better in Performance as compared to XmlSerializer.
In what scenarios must WCF be used
A secure service to process business transactions. A service that
supplies current data to others, such as a traffic report or other
monitoring service. A chat service that allows two people to
communicate or exchange data in real time. A dashboard application
that polls one or more services for data and presents it in a logical
presentation. Exposing a workflow implemented using Windows Workflow
Foundation as a WCF service. A Silverlight application to poll a
service for the latest data feeds.
Features of WCF
Service Orientation
Interoperability
Multiple Message Patterns
Service Metadata
Data Contracts
Security
Multiple Transports and Encodings
Reliable and Queued Messages
Durable Messages
Transactions
AJAX and REST Support
Extensibility
source: main source of text
MSDN? I usually do pretty well with the Library reference itself, and I usually expect to find valuable articles there.
In terms of what it offers, I think the answer is compatibility. The ASMX services were pretty Microsofty. Not to say that they didn't try to be compatible with other consumers; but the model wasn't made to fit much besides ASP.NET web pages and some other custom Microsoft consumers. Whereas WCF, because of its architecture, allows your service to have very open-standard--based endpoints, e.g. REST, JSON, etc. in addition to the usual SOAP. Other people will probably have a much easier time consuming your WCF service than your ASMX one.
(This is all basically inferred from comparative MSDN reading, so someone who knows more should feel free to correct me.)
WCF should not be thought of as a replacement for ASMX. Judging at how it is positioned and how it is being used internally by Microsoft, it is really a fundamental architecture piece that is used for any type of cross-boundary communication.
I believe that WCF really advances ASMX web services implementation in many ways. First of all it provides a very nice layered object model that helps hide the intrinsic complexity of distributed applications.
Secondly you can have more than request-replay messaging patterns, including asynchronous notifications from server to client (impossible with pure HTTP), and thirdly abstracting away the underlying transport protocol from XML messaging and thus elegantly supporting HTTP, HTTPS, TCP and other. Backward compatibility with "1-st generation" web services is also a plus.
WCF uses XML standard as the internal representation format. This could be perceived as advantage or disadvantage, especially with the growing popularity "fat-free alternatives to XML" like JSON.
The difficult things I find with WCF is managing the configurations for clients and servers, and troubleshooting the not so nice faulted state exceptions.
It would be great if anyone had any shortcuts or tips for those.
I find that is a pain; in that I have .NET at both ends, have the same "contract" dlls loaded at both ends etc. But then I have to mess about with a lot of details like "KnownType" attributes.
WCF also defaults to only letting 1 or 2 clients connect to a service until you change lots of configuration. Changing the config from code is not easy, shipping lots of comfig files is not an option, as it is too hard to merge our changes into any changes a customer may have made at the time of an upgrade (also we don't want customers playing with WCF settings!)
.NET remoting tended to just work most of the time.
I think trying to pretend that .NET to .NET object based communications is the same as sending bit so of Text (xml) to an unknown system, was a step too far.
(The few times we have used WCF to talk to a Java system, we found that the XSD that the java system gave out did not match what XML it wanted anyway, so had to hand-code a lot of the XML mappings.)