Is it even possible more or less natively consume WCF service from Go application?
I can imagine it should be possible to execute SOAP calls in Go, but WCF is a bit more than that only, for example authorization will probably be a problem also...
Have anyone at least approached this area, or maybe someone can give useful me advice in this "wheel reinvention task"?
Thank you in advance for all your input, ideas and suggestions.
I think you should expose a RESTful Service. I myself have the problem with exposing a WCF Service too many clients using PHP, Go, Ruby and all kind of languages. We never ever got it right, to automatically generate a proxy.
The maybe simplest way is to use WCF, like described in this example:
https://www.codeproject.com/Articles/105273/Create-RESTful-WCF-Service-API-Step-
By-Step-Guide
But I recommend to switch to ASP.NET Core (Migration is not that hard) or if you have the budget I would consider https://servicestack.net/
It may be well beyond the wait time for this. However, here is something really interesting that could help. The situation the authors found themselves is relevant even today in some organizations.
https://github.com/khoad/msbingo
Here's the motivation provided by the authors:
Application/soap+msbin1 encoding was a blocking issue for modernizing services from WCF to platform-agnostic technologies such as Go. We needed to be able to make calls to dependency services that spoke msbin1 and were not going to be updated or even reconfigured, but we did not want to introduce unnecessary complexity such as workarounds like .NET-based WCF request translator proxies or deploying Mono with our service instances. Initially we tried the Mono deployment route, which, while it would have worked well enough, significantly complicated our deployment pipeline, thus erasing one of the major advantages of golang.
I found it a useful starting point to begin experimentation.
I'm just about getting into WCF; but from what I've read so far, like the sample scenarios I found on MSDN and some other sites, I can do all that with web services and applications that call those web services. So why the need for an elaborate layer like WCF?
Most of the comparisons I've googled for explain it more from a programming point of view. Still trying to find answers without much success as to when it makes business and of course programming sense to use the WCF layer as opposed to traditional application to web services model.
Anyone here with experience on both and can advice on how to go about choosing either web services or going the WCF way? What are those things that can't absolutely be done using just plain old web services called by applications and where the WCF layer will save the day.
You've fallen for the Microsoft trap of "it's just about web services" :-)
It's actually a lot more:
it's about service-oriented programming in general (not just web services - you can also write TCP/IP based services, MSMQ queue-based messaging and a lot more)
it's about unifying all the diverse programming models that existed so far (ASMX, Enterprise Services, DCOM, .NET remoting)
it's about providing a lot of ready-made and ready-to-use plumbing which can handle things like reliable messaging, transaction support, security in any shape or form you'd like, service discovery, and a lot more
it's about separating the service implementation from the details of how clients will call it and making this a configurable stack of protocols, encodings etc.
Sure - most of this stuff can be done in ASMX, or .NET remoting - but try to convert an ASMX web service to be callable in your intranet using TCP/IP and transport security... Many of those "older" technologies have a very intricate and direct link to how they're being used - you can't easily change that without changing the whole service code.
WCF separates all these "plumbing details" like what endpoint to call, what protocol to use to call it, how to handle security etc. out into a "WCF stack" that's configurable and composable, so you can easily switch your service XYZ to use HTTP allowing anonymous users to call it, to using TCP/IP with Windows credentials required - your service code won't change a bit - it's only configuration of the plumbing.
That to me is the most compelling reason for WCF - I can totally concentrate on my actual service code, and not pollute it with lots of plumbing stuff - how to handle transports and text encodings and all that. And I can easily change that and adapt to new requirements and needs in deployment without having to touch my actual service code.
Plus, the second major point is extensibility - most of the older technologies just had their one, set way of doing things and many didn't lend themselves to being extended. You had to either adapt to use it the way they did it - or forget about it. WCF has a vast and very intricate system for extending just about anything - you can create your own transport protocol (people have created UDP or SMTP based bindings), you can create your own message encoders (like I had to do to talk to a web service which could only understand ISO-8859-1 encoded messages), and you can extend just about anything else in WCF - all in an organized, well-documented, very stable and safe way.
So these two things - separating out plumbing into configurable layers, and extensibility to the maximum - are the most compelling reasons for me to use WCF.
Edit: Kobi's link above, is a far better answer than mine.
WCF is basically a better architecture for supporting communications. It breaks many dependencies such as hosting (not iis dependent), transport, security, addressing into plugin components, and allows customisation to a very high degree.
Yes you can do a lot with traditional technologies, however you can do more with WCF. If you don't need the features now then of course you can can continue with legacy technologies, however if you prefer you can opt for a better architecture now with an eye on the future but it comes at a cost of having to switch technologies now.
Take this example. If you have a legacy asmx web service, how easily can you offer the same service via an MSMQed endpoint? With WCF its as simple as adding new config settings.
I assume that you are not asking "why not just stick with SOAP/HTTP". WSF allows you to choose a number of different transports rather than just simple HTTP, but as you observe the WS-* technologies allow you to do all that. So I think you're asking why use a powerful but complex framework when the raw technolgies are not impossibly complex?
You could ask this same question of any Framework. You could just use the basic technologies and avoid the learning curve of adopting the framework.
Frameworks such as WCF do have a learning curve, but consider what happens if you don't use them:
You find that you write boiler-plate code for each service invocation. You then either accept duplication or begin to refactor and build your own libraries. Before long you've developed your own Framework, but it's not the same as anybody else's. So then any new team memeber has to learn your local framework, serious learning currve.
Note also that WCF addresses issues such as the monitoring of the deployed solution.
The biggest appeal to me is testability. Services are defined by a CLR interface, which is quite easy to mock inside a test harness. Some words of warning, however. With great flexibility comes some pain in the configuration process, along with a few "gotchas". An example of a gotcha is that WCF--adhering closely to a "best practice"--requires an active SSL connection in order to pass SOAP authentication credentials over HTTP. This hinders testing quite a bit.
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!
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.
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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.)