I'm a bit new to WCF, so please bear with me. I have a very simple REST Service written up using .NET 3.5, which is exposed through a asp.net web application through a SVC file. Everything is working as expected.
What I would like to know is if it is possible for me to create a plugin structure in WCF, so that I can have third party developers write up expose their functionality through my service. I'm hoping it's possible to dynamically create my endpoints through code, at the moment everything is in my web.config and service.svc files (as far as exposing the contract).
In the end, what I would like to have an active running service that auto checks for new assemblies (if added to the plugins directory), and would automatically add new endpoints, which could have completely different functionalities. One could be a file transfer plugin, another could be a calculator, etc.
But first I need to know if it's even feasible... currently I'm looking into MEF to see if that might help out, as I'm used to just loading DLLs manually (in Desktop apps).
It is possible to use MEF through WCF, I have worked on a similar project in the past. You could expose functions from the plugin DLL's through MEF assume the implementer of the MEF interface is implimenting a function that starts a new WCF service with it's own end points, then call that function from the main service.
See some sample projects below, although none of them are doing what you are asking it is possible that the MEF plugins could have a service host that's starting their very own service with their own end points.
Creating WCF Service Extensibility through MEF
A sample demonstrating how WCF and MEF play together
Related
Looking at an earlier 3.5 based solution, there is an WCF service within the same web project. I thought WCF services generally got their own project.
I usually separate my WCF projects out for maintenance purposes, but they can be within a web project. It is basically the same thing as the old ASMX [WebMethod] process. In fact, any method in a code-behind of a web form can be turned into a web service method by decorating the method accordingly.
I am using Biztalk UDDI V3 (stand-alone install) on a windows 2008. I have configured all services (web, database and subscription):
I successfully published a couple of services
I successfully accessed and retrieved service information from my .net console application.
My issue at this point is with the subscription service. I tried to subscribe to one of the published services only to find out that I need to create my own listener.
I followed the steps listed here. Please take a look at the section entitled "Building subscription alerts for service changes". I am confused as to what the WCF service I create is supposed to look like. The instructions state the following:
Now we create a new WCF Service project and reference this existing service library. After making sure the .svc file points to our referenced library object, and adding a valid endpoint configuration file, view our service in the web browser to ensure that it's up and running.
I find this section confusing. Not sure what public methods would the WCF service expose(if any at all) or how to expose the functionality within the service library that I just referenced from within my WCF project.
Of course, if you know of a different way to achieve what I am trying to accomplish, that also would be much appreciated.
Thank you.
This may help. I actually just wrote a complete port for Apache jUDDI's client library using .NET C#. One of the use cases is actually what you are attempting to do. Here's the rough approach used.
Generate the code from wsdl (using wsdl.exe, because svcutil doesn't like the UDDI wsdls)
Alter the interface code to have WCF bindings for the Subscription Listener class
Create an implementation of the subscription listener and handle the callbacks
Fire up the implementation using WCF's embedded service
Register your sub listener endpoint with UDDI (using the correct annotations per the spec)
Setup the subscription using your sub listener's binding template
Wait for callbacks
Here's the code
http://svn.apache.org/repos/asf/juddi/trunk/juddi-client.net/
Example
http://svn.apache.org/repos/asf/juddi/trunk/juddi-client.net/juddi-client.net-sample/org.apache.juddi.client.samples/SubscriptionCallbackExample.cs
There's also a Java version that does the exact same thing.
Allow me to explain a little better.
I have a VS2010 Solution, split into 2 projects: a WCF Web Service, and a Class Library that uses the Web Service.
The WCF Web Service is a simple logging service; namespace "LogService", service "LogService", contract "ILogService".
When you use the "Add Service Reference" utility that comes with VS2010 to add a reference to the WCF, into the consuming Class Library project, you will see that the tool correctly adds a reference to a Web Service that can be called through "LogService.LogServiceClient". No problem here.
Now, I have another Solution; this is also split into 2 projects: another WCF Web Service, and a Web Application that uses this new Web Service.
This particular Web Service provides operations performed on a database; namespace "BLService", service "BLService", contract "IBLService".
Using that very same "Add Service Reference" utility in this project, however, adds a reference whose client name is actually "BLService.IBLServiceClient". Please notice there is a "I" prepended to the service client class name. The utility seems to have decided it should use the contract's name, instead of the service's name, to create the service client class.
I don't understand why does the tool behave differently on both Solutions. I've tried checking everything I could from both, and I can't find no significative differences (to my knowledge, at least).
Do you people know why does this happen? What things should I check, and correct, in my Web project (or anywhere else in the solution) so this odd behavior does not happen anymore?
I am new to both Silverlight and WF (both 4.0 version), i was wondering if we can integrate WF4.0 with Silverlight 4.0 in such a way that, when we click on some button in sliverlight UI the workflow should be executed and the output from the final activity of the workflow is displayed in the Silverlight screen. If it can be done then please provide me with some link or any tutorial where i can learn about this and start implementing.
Thanks in advance.
In WF 4.0 you can have workflows started (or progressed) by WCF endpoints. Therefore, if you can call the WCF endpoint from your Silverlight application you should be able to do this quite easily. Lots of information on Microsoft's WF Developer Centre.
Assuming you are using Visual Studio 2010, you can get up and running with a very simple Silverlight -> WF example very quickly...
Create a new project (and new solution) from the 'WCF Workflow Service Application' template. The project will be named DeclarativeServiceLibraryX. This should give you a very simple WorkflowService definition using SequentialService that simply receives the request from a client (with a single integer argument) and sends a response (with the same value). This project is created as a web project so includes a Web.config.
Create a new Silverlight 4 application. You will be asked if you want to host the Silverlight app in the existing web project (created in step #1). Probably a good idea to say yes.
In the Silverlight application, select 'Add Service Reference...', then 'Discover/ Services in Solution'. Service1.xamlx will appear as an option, select it and click Ok.
VS will then generate a WCF service reference client. You could then add a TextBox & Button to capture some data, create the client and send the service call across the wire to the WCF Workflow Service. This Workflow Service could then be modified as necessary (or use these steps to add a WCF Workflow Service to your own web project).
One area that might be challenging is modifying the WCF service bindings to be compatible with Silverlight; perhaps create a Silverlight-compatible WCF service in your server-side project first, then create a WF WCF endpoint and look at the generated code & config to see how to put things together.
The MSDN Endpoint blog is also a useful resource for learning more about WF and WCF (especially with the new style lightweight REST-style 'WCF Web HTTP' bindings, which might be more suitable for consumption by a Silverlight client.
I am assuming that you don't want to host the workflow inside the Silverlight app itself, as WF is a full .Net framework component rather than being Silverlight compatible. I'm sure you could write your own lightweight workflow framework that runs inside Silverlight, but given workflow is generally a multi-user, server-side concern this probably wouldn't be very useful concern.
I found an example with WPF here for these samples. Hope they will help you a bit or at least give a general look at this topic.
Workflow Foundation is not included in the Silverlight 4.0 runtime and thus cannot be used within a Silverlight app. So Silx answer do not relate at all to Silverlight. And James Websters answer is the only solution to make use of WF from Silverlight.
You cant use WF with silverlight.... the only way is , You can call WCF service to access WF as explained by James Webster.
I am working on a Silverlight application that uses WCF. I need to have my WCF project separate from the ASP.Net application that will host my Silverlight project. I am looking for some guidance on how I should organize my solution and list gotchas other people have experienced during debugging and deployment.
Specifically my questions are
What type of project should I use for the WCF service?(A WCF project, an ASP.NET project with self-hosted WCF services, something else)
What do I need to so to get it so that when I press F5 I can debug both my Silverlight project and my WCF service? Will I need a cross-domain policy just to debug the thing?
Some background info on why I want to do this:
I have legacy web application that I am gradually converting over to a Silverlight application. Because it is a large web application some of its features will be converted to Silverlight before others.
The legacy web application has lots of code in it that is no longer used. Much of the code that is no longer used references 3rd part assemblies. This is why I want to get rid of the old web application. So obviously I don't want to host WCF services that will be kept for future versions in it. That is my reason for wanting to make the WCF project separate.
We're doing the exact same thing.
We're using a WCF project just in case we have to change how it's hosted in the future. (I.E. no longer using IIS)
2.a. You can have a solution with your silverlight projects, and your wcf project. The silverlight project will have a service reference to the wcf service in your solution. That allows you to debug using F5. However, when you go to deploy, you will have to change your app.config service URIs to refer to your production location.
2.b. You will only need a cross-domain policy file if your fully qualified domain names are different for the wcf service and the silverlight app. Ours happen to be different. Here is an excellent article on when to use the policy file: Clicky
Good luck!
Just remember that when you get ready to deploy, if your service is going to be hosted on a different machine than your app, you need to deploy the service first. Then re-configure your service reference, and finally re-compile your Silverlight before deploying. Otherwise, your Silverlight app will look for the service on your local machine instead of where you deploy it.