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As part of the workflow service project, I need to build an XML querying framework.

For this to work on the back end, I would like to use Linq - but in order to do so, I need to have it be capable of handling dynamically generated queries derived from the query XML coming into the service.

It appears that Microsoft has produced samples of this - Dynamic Query.

There are a number of good examples around:

ScottGu's dynamic query example:

Linq Dynamic Query C# class

Blog post that includes a join example:

The issue though with Dynamic Linq is that you appear to trade the strong typing associated with standard Linq for the flexiblity of Dynamic query.

A query executed with Dynamic Linq returns as a type of 'DynamicClass1' etc. which cannot be cast to other types. This means that a generic mapping process of some kind would have to be used to get the data back into some kind of strongly typed form.

In the case of what I am working on, I don't need the strong typing. I am working on setting up a service entry point for generic querying of data associated with the service in question. The query language coming in will be constructed in XML, and defined using a typical XML query pattern.

These queries will be translated to dynamic linq, which is then executed and mapped back to XML from the generic dynamic class generated.

I have been constructing a workflow based service engine using WCF and WF with the intention of using infopath forms to route data through the engine.

Fortunately, the company that supplies our Project Services Automation system BSTGlobal has built just such an engine they call BSTFX. This tool is a set of service contracts and objects coupled with a management console and WCF hosting system that takes quite a bit of the work out of building a stable service oriented workflow.

One of the tricky bits though has been figuring out how to get Infopath to talk to a WCF service.

Using SSIS from M$ SQL 2005 to build a massive data import for an accounting system (yes very painful). SSIS itself looks very good - however, I have been running into a few strange things.

For no particular reason, my packages stopped opening with a somewhat cryptic error that indicated the packages had been 'corrupted':

"package might be corrupted ssis"

Resolution turned out to be to re-regsvr the XML dlls. Don't know how, why or what would cause them to become unregistered, or why it would affect SSIS outside of their being required to parse the XML that makes up the package... At any rate, if you experience that error, then run:

regsvr32 msxml3.dll
regsvr32 msxml4.dll
regsvr32 msxml6.dll

This should clear it up...

I have been hearing a lot about this both from Microsoft and from developers/companies I know in town.

Its a Don Box creation, and looks absolutely excellent. I was planning to build up a workflow engine of my own, as I require one for a number of things that I am working on, and have tried Biztalk a few times, only to find that its too complicated and fiddly for most workflow related tasks. I will have a look at the new version of Biztalk that is coming out shortly, but I think this Windows Workflow looks a great deal more applicable for most of the cases I am working on.

Article on best practices for team development with Biztalk. I have found lots of articles on how to set biztalk up, but just this one thus far on getting a team environment setup for developing...

Found some more - this looks quite interesting:

http://www.manageability.org/blog/stuff/open-source-etl/view

This MC Eagle software handles EDI!! http://www.mec-eagle.org/

Enhydra Shark: http://shark.objectweb.org/
Looked good but fairly complicated - java based.

Bonita - http://bonita.objectweb.org/html/Download/index.html 
Looks promising: java based workflow engine, liscensed LGPL, can use MySQL as database

PetriNet based PHP workflow engine
Couldn't find a download, but describes a workflow engine design in detail: http://www.tonymarston.net/php-mysql/workflow.html

Gluecode Joe - http://www.gluecode.com/website/products/licensing.jsp
Looks promising allows free, unlimited distribution of the binary code

Workflow Patterns:
http://tmitwww.tm.tue.nl/research/patterns/index.htm