My sixth sense of a developer at SAP Labs has giving me a hint that SAP customers are not doomed to use only SAP software. If someone uses SAP products, then it is natural to expect that she has looked at other vendors and has considered taking their best bits of software. And at the end when putting all these pieces together, the expectations are that they talk to each other.
This assumption of mine has been recently confirmed by a customer who has chosen SAP NetWeaver CE as a development platform, but also has plenty of licenses for IBM Rational Software Architect. And, rationally, the customer find it very useful to utilize his IBM Rational tools for development on top of the SAP NetWeaver CE.
Failing to install IBM RSA on top of SAP NWDS, due to the different Eclipse versions they are based on, the customer found the SAP NetWeaver Server Adapter for Eclipse to be the solution for his wish. Being a tiny plug-in that integrates the SAP NetWeaver Application Server Java into any Eclipse-based IDE, the server adapter is the crux to bring not only IBM Rational tools to the SAP NetWeaver platform, but any third-party vendor products based on Eclipse.
So, if you have already spent some money on IBM Rational software, just give it a try together with the SAP NetWeaver platform.