Question: I am currently looking for a good framework to integrate multiple systems with different communication methods like

* FTP
* Mail
* Queue
* Web Service

in a .NET application. For Java there seem to be a lot of options available, but I could not find anything similar for the .NET platform.

Answer: 
The Workflow Foundations are more suitable for... well.. work flows representing the business logic. You seem to be more interested in integrating existing services. In that case I would focus more on the Windows Communication Foundation. Which were introduced together with the (original) Workflow Foundation. So WCF is part of .NET Versions 3 and above. WCF will support Webservices, Message Queueing and FTP out of the box. For email you will probably need some kind of custom channel. However, it's highly likely that someone else has already written one for you.

[According to Microsoft](http://msdn.microsoft.com/en-us/library/ms731082.aspx): 

> 
> "Windows Communication Foundation (WCF) is a framework for building
>  service-oriented applications. Using WCF, you can send data as
>  asynchronous messages from one service endpoint to another. A service
>  endpoint can be part of a continuously available service hosted by
>  IIS, or it can be a service hosted in an application. An endpoint can
>  be a client of a service that requests data from a service endpoint.
>  The messages can be as simple as a single character or word sent as
>  XML, or as complex as a stream of binary data."
> 
> 
> 

[This page](http://msdn.microsoft.com/en-us/netframework/dd939784) on MSDN contains resources to help developers get up to speed on developing with Windows Communication Foundation (WCF). Keep in mind, all of this concerns only the communications layer. You'll have to write glue-code yourself.

If you really want a more "framworky" solution, I'd agree with Tommy Grovnes. 'Service Bus' is the buzzword to search for. In fact Stackoverflow already provides many [insights](https://stackoverflow.com/search?q=.net%20service%20bus) on what services busses are good for, what implementations exist, experiences with them and so on. Especially [this question on .NET service busses](https://stackoverflow.com/questions/1545442/net-service-bus-recommendations) looks like a promissing start. 

Cheers

dave
I suggest you have a look at [Windows Workflow Foundation (WF)](http://msdn.microsoft.com/en-us/library/ee342461.aspx). It's part of the .NET Framework.

It uses the concept of Activities. An activity is a general concept, and is also well suited for "connectors" to other systems. Some out-of-the-box activities are provided ([.NET Framework 4 Built-In Activity Library](http://msdn.microsoft.com/en-us/library/dd489459))

Others can be written in .NET ([Tutorial: Create a Custom WF Activity](http://msdn.microsoft.com/en-us/library/ms734563%28v=vs.90%29.aspx)), you can also find numerous sample implementations on the web ([Workflow SendEmail Custom Activity](http://www.codeproject.com/Articles/36774/Workflow-SendEmail-Custom-Activity), [FTP Activity for Windows Workflow Foundation](http://www.codeproject.com/Articles/38239/FTP-Activity-for-Windows-Workflow-Foundation), [MSMQ Workflow Activities](http://winterdom.com/2006/03/msmqworkflowactivitiesv1), [Building and Testing a WCF Web Service Using Workflow Foundation 4.0](http://www.codeproject.com/Articles/95418/Building-and-Testing-a-WCF-Web-Service-Using-Workf)) or you can also buy already built specific activities from 3rd parties ([Xceed Activities](http://doc.xceedsoft.com/products/XceedWfWorkflow/), [/n software Workflow Activities](http://www.nsoftware.com/workflow/default.aspx), etc.)