SSRS is a great tool for quickly retrieving data and presenting the data to the user at a run-time decided format. One area where SSRS often falls short is when the underlying data needs to come from several different sources. Perhaps we want to retrieve data from the General Ledger which is in Oracle, and join that against a list of departments and employees which are stored in SQL Server for us to display in one table. When this happens, it is quite often not possible to join them into one dataset, and we are stuck with some difficult design problems for the report.
Here is a sample SSRS DPE (Data Processing Extension) project SCS has put together on Code Project as a starting point for any interested developers to work from. Depending on the specific needs of the project additional development will be required, but we have created a starting point for anybody that needs to use SSRS to report data coming from two or more different databases.