We've tried to make it as easy as possible to work with BDC Meta Man so that you can generate the XML application definition files you need to use with the Business Data Catalog. This has always been easy for data sources such as Oracle, SQL Server, DB2 etc but SAP has always been very painful due to the web service methods it provides you with out of the box. For example to use the Business Data Catalog with web services you want nice methods such as:
[WebMethod]
public List<Product> GetProducts()
[WebMethod]
public Product GetProductById(int productId)
[WebMethod]
public List<int> GetProductIds()
Those among you who have been working with the BDC will notice that these web methods implement BDC type methods of Finder, SpecificFinder and IdEnumerator. If the web services you want to use aren't like this then you are going to have a hard time using them with the BDC. I know some instances of companies who have written web service wrappers around the SAP web services!
So it's been our mission to make SAP and BDC integration a lot easier and we are comfortable that we've done it! Lightning Tools together with Sitrion have partnered to bring the knowledge of SharePoint and the Business Data Catalog, and SAP together.
The first place to start is with Sitrion's iQL Studio. You can model metadata-driven from within Visual Studio 2005 and 2008 that leverage SAP functionalities like BAPIs, RFCs, Queries and Workflows.
iQL Studio allows the developer to simply drag & drop SAP functionalities to a design surface and model an abstracted and documented Business Entity. Even testing of SAP functions (like SAP transaction SE37) is integrated into iQL's toolkit. iQL also features composite methods that are able to execute calls against multiple SAP functions and also allow the usage of custom embedded .NET code.
Once an iQL Business is modelled it can be published with one single click to Microsoft's IIS as a pure .NET WebService! From here you can start using BDC Meta Man and create powerful MOSS integration scenarios.
For more information and some images of the tools in action please see our page here:
http://www.lightningtools.com/sap/business-data-catalog.aspx