Folks,
I'm building a pretty standard workflow that I want exposed via a WCF endpoint - I'm using the "WCF Service Application" project template and I've got a .xamlx service. This is a very simple document interchange workflow service - I want consumers to POST me a blob of XML as the body of an HTTP post (with HTTP headers containing authentication tokens). In response, these consumers will get a blob of XML containing the reply. 2 goals for me using REST/POX here are the document/message-based nature of the interaction AND I want to make client development easy for non-.NET environments (especially limited environments like Silverlight and iPhone).
I don't really see how to make this possible using out of the box features (unless I'm missing something). Does anybody know how to create a RESTful (or even REST-ish, I'm not picky) endpoint for a WF4 service-hosted workflow? Any info leading in the right direction here would be great.
There is an unreleased item on CodePlex to cover this, which includes source code. Also see this SO answer which contains another idea for achieving this.
If you'd like to see the CodePlex activity released, please up-vote the UserVoice request.
Using a REST Pass-Through Service
As #Maurice mentions, you can also treat the WF service as a back-end service and expose a REST service that simply calls through to the WF service.
This method is a bit clumsy, but has the advantage that it doesn't use anything unreleased or really complicated.
If the back-end service runs on the same machine as the REST service (which is probably what you'd do), you should expose the WF service using the named pipes binding. This binding is fast, but only works when the caller and callee are on the same box.
A further thought: your REST pass-through service is blocked while the back-end service is being called. If your WF service is not very fast, you'd benefit from making your REST service asynchronous so it doesn't block a thread pool thread while the WF service is being called.
There are no out of the box activities that will allow you to use REST with WF, the Receice is pure SOAP.
You can either build a custom REST Receive activity and use that with your workflow. Depending on your needs this is going to be quite a handful to a lot of work. The easy option is use use a standard REST WCF endpoint and convert the REST data to SOAP, pass rhe request on to the workflow, and do the reverse on the result message.
Related
I have a third-party Java web service listening at three SOAP 1.1 WSDL endpoints. One of the endpoints is used to initiate the session and perform some high-level tasks, and the other endpoints are for subject-specific tasks reusing that initial authentication.
I'm building a C# WCF application to talk to the service, and I'd like to share the session cookie among the three client objects.
What's the VS2010 'best practices' way of sharing this cookie?
If this article is still the best answer, I can go with it, but I would appreciate some additional feedback, especially if .NET 4 introduced a simplification that I'm not finding on-line.
http://megakemp.wordpress.com/2009/02/06/managing-shared-cookies-in-wcf/
I can pretty easily create the first client and retain the session (new BasicHttpBinding myBinding; myBinding.AllowCookies = true), but I couldn't find an elegant way of saving off the cookie from the Connect response and reusing for the two auxiliary clients.
Any insights are appreciated.
I should note that I'm aware of CookieContainer and using Add Web Reference instead of Add Service Reference. That method is labeled as 'legacy' in most posts I've read, and I'd prefer to stay current...or as current as possible when working with SOAP 1.1.
The mentioned article is still valid. You have to use OperationContextScope and access message properties to get protocol specific data. This complexity is based on the fact that WCF architecture is protocol independent whereas ASMX architecture was HTTP protocol dependent.
It is true that ASMX (WebReference) is legacy technology but it is still present in .NET framework so if you know that you will never need nothing more the basic SOAP messaging without any advanced WS-* standard you can still use it and make your life little bit simple. Once you need anything more you can still refactor your code and use WCF with mentioned code to work with cookies.
I have a web service that is used by many different clients using many different languages.
I want to switch it to wcf to take advantage of the many different endpoints.
However what has been stopping me is that I am afraid that the clients will have to use a special sdk to connect (if they are using java or php or some other language) that is different then the sdk they use to connect to the existing web service.
Is this true? Or is connecting to WCF the exact same as it is for web services in other languages.
The project I am currently working on has multiple WCF configurations, some are using the default SOAP implementation, and some are using a POX (plain-old-xml) style message.
So the short answer is 'yes' you can configure WCF in such a way to work with just about anything.
However, be warned that as soon as you step outside the default little box that WCF has set up for you, it gets pretty complicated. You end up with a lot of custom message parsing and security handling if you go to a POX message format. Its easier if you stick with SOAP though.
As for needing a 'special SDK' you won't. You can communicate with WCF with simple HTTP POST messages if needed.
I have clients that are using VB.NET apps (using SOAP) and Java apps (using POX) to hit my WCF services.
A basicHttpBinding endpoint in WCF is exactly a standard SOAP endpoint, and your Java or PHP clients will not have to change in any way.
I have two related questions about Web services:
(1) I'm currently writing a set of applications, and it occurred to me that maybe I'm not using the right tool for the job. Here is the spec:
There are many Windows servers behind different VPNs and firewalls.
Each of the servers has a Windows service running, that reports various information about it to a centralized server, via a Web service, both of which I've written, and have access to.
So I'm both the producer and the consumer, and I'm staying on the same platform (.NET). Maybe a web service isn't the way to go? I'm using one purely because it's easy to write and deploy, and I'm the most comfortable with them. Should I really be using WCF for this?
(2) In the web service, I'm creating a State object to represent the state of the server, and sending it as a parameter. However, adding a service reference creates a proxy of the State class. It seems gacky to copy the properties of the State object to the proxy, and then send the proxy. Should I just replace the proxy class with the real class in the auto-generated code (i.e., include a reference to the State class instead)?
By "web services" I assume you mean an ASMX? I would go with WCF is possible, simply because you lose nothing but gain lots of flexibility. You could, for example, switch from XML-over-HTTP to Binary-over-TCP through a simple config change.
I would suggest to use WCF and use the Net.Tcp binding. It should be efficient enough for 300 clients. For the proxy class issue use the /reference option for the svcutil tool when you generate the proxy. This will allow you to share classes between server and client. I would not use this option if interoperability was a concern but since you stated that you develop both the clietn and the service and all in .Net it is a valid use in your case.
Your distinction between "Web Services" and WCF is a false distinction.
ASMX Web Services is the original .NET SOAP Web Service technology, introduced in .NET 1.0. It has been replaced by WCF, which can everything that ASMX can do, plus a whole lot more (including support for the WS-* standards).
Microsoft now considers ASMX Web Services, and the XML Serializer they're based on, to be "legacy technology". See "Microsoft says: ASMX Web Services are a “Legacy Technology”".
With WCF, since you have control of both sides of the operation, and can share the .dll in which the service contract is defined, you can and perhaps should be using ChannelFactory<IYourServiceContractHere> instead of auto-generating those ugly proxy classes with service references.
Here's the first hit I found on this topic: http://blogs.msdn.com/juveriak/archive/2008/02/03/using-channels-vs-proxies-in-wcf.aspx
If it is platform independent, I would certainly recommend WCF.
I've done exactly what your describing to great effect across more than 300 locations. I don't think you made the wrong call.
Another thing you could consider that would work well is using MSMQ. In this case, however, you'll either need to write event triggers (COM) or an event queue processing service.
I have a Windows Service which performs a certain function, and then needs to send that information off to a webservice for processing. The webservice is hosted by a remote web application. I am trying to ascertain the best way to call the webservice(s) as each web application might be only 2.0, or 3.5 etc. In my windows service, I am defining each "client" in the app.config, e.g.
<Client WebServiceUrl="http://location.com/webservice.svc" Username="" Password="">
</Client>
The web application must implement two web services that are required for my windows service to run, however not sure the best way to implement the "rules" for the web application.
EDIT:
I'll try and rephrase..
The Windows Service runs every 30 seconds and obtains a list of information. The service supports multiple "clients" as shown above. When each client process is run, the data is collected and is then needed to be sent to the supporting web application.
The windows service does not know what to do with the data, it is just sending it. Each web application for a client would be in different locations, and could possibly be built in 2.0, 3.5, PHP, etc. All the windows service cares about, is that when it performs its processing for a client, it is able to send the data to the webservice location defined in the app.config of the windows service.
What I'm trying to determine is how to connect to the webservice (which I'm leaning towards WCF, however Basic or WS not sure), and what rules need to be defined for the web application in how to build the response.
If the Windows service is to support php applications etc, WSHttpBinding would not be an option, which would mean BasicHttpBinding would then work. The other thing to decide is whether or not to utilise a RESTful service or SOAP service.
Hope this makes more sense.
I'm not really clear on what you are doing.
It seems like you have 3 things: A Windows Service, and then a web service, hosted in a web app.
I think your question is, what to use, REST, ASMX, WSE or WCF, when interconnecting the Windows Service app with the remote web service.
ASMX, WSE and WCF are alternative programming models for the web service. REST is not a programming model. It is not like the other three.
ASMX and WSE will require that you use Web services and SOAP.
WCF can allow you to use Web services and SOAP, REST (XML or JSON) over HTTP, or a binary format over TCP, among other options.
Because it is flexible and current technology, I'd recommend WCF. ASMX is now termed "legacy technology" by Microsoft. Doesn't mean it won't work, but it will not get updates. (Much like WinForms versus WPF). WSE is no longer in mainstream support, as far as I know. For these reasons, I wouldn't recommend starting a new project on WSE, nor on ASMX.
WCF is more general than ASMX and can seem more complicated, for that reason. But once you make some choices and zero in on what you want (for example choose HTTP and REST, or choose binary and TCP), it's more powerful. WCF can be used as the programming model on both the client or sender (in your case, the Windows Service, I guess) and/or on the server (the web service hosted in the web app).
Using WCF on the client side does not imply you must use it on the server side, and vice versa. On the other hand, if you control the source code on both ends, I would recommend using WCF on both sides.
As for "how to implement the rules for the web app" - I don't understand what you are asking there. Maybe if you are more specific on the question there, someone will be able to help out.
Update: Based on your additional explanation, I'm going to suggest you look at the REST stuff in WCF for .NET 3.5. In PHP it's very easy to implement a REST-style service, and with WCF, the same is true for .NET. Now in your case the Windows service is the client and it is sending out a request, an update request, to various servers that reside on your customers' networks. According to REST principles, I'd make those outbound requests PUTs or POSTs, depending on the semantics of the call.
Then you could ship some example service code to your (uppercase) Clients, to get them started on building what they need to receive your outbound PUT/POST messages.
Security is a concern though. You didn't mention it at all, which is surprising. Security is not one of those things best deferred, so that you "add it on later". You should think about it early - it may affect the protocol choices you make. For example, if you need to mutually authenticate the clients and servers (the latter at your "uppercase" Clients' networks), then you may want to go with SOAP, which gives you good options on the protocol side for security. Secure Web services extensions (WS-Sec, etc) are well supported in WCF, but not sure about the status of this capability in PHP.
I'm looking to understand when to use a WCF services instead of just using webclient or httpwebrequest. I guess I'm also looking to understand the difference between the design patterns that would be appropriate for both.
Are you talking about when to create a WCF service yourself (over web service), or when to consume an existing web service using WCF instead of .NET 2.0 ASMX clients?
As for creating a WCF service yourself:
Gives you a lot more options in terms of hosting (in an app, Windows Service, IIS, WAS)
Gives you a lot more security options
Gives you a lot more protocol options (besides just HTTP, you can also use WS-*, TCP, Named Pipes, MSMQ and more)
Allows you to write your service once, and expose it on multiple end-points with different protocols at the same time
As for using WCF to talk to an existing HTTP (ASMX) web service - I don't see a whole lot of massive benefits, except WCF uses more configuration over code, and it can be good to standardize on one way of doing things, if you already use other WCF services, anyway.
Marc
I'm currently using WCF for most of the things that I would use WebClient or HttpWebRequest/HttpWebResponse in the past. While there definitely is overhead for learing how to make calls to web methods using WCF, the extensibility of WCF and the abstraction it provides makes it a MUCH better candidate for these types of calls.
I've already used it to make calls to Akismet and RPX pretty easily.
To get started, I'd look at the section of the MSDN documentation titled "WCF Web Programming Object Model", located at:
http://msdn.microsoft.com/en-us/library/bb412204.aspx