I have to integrate my web service with IBM Enterprise Service Bus (ESB). I think that there should not be any mediation because this service has only one location and do not have to change requests. Is it true? Can ESB administrator simply connect web service to the bus?
If it is necessary to write mediation code: are there any free tutorials and tools to create such mediation or I have to buy WebSphere Integration Developer (WID)? This mediation should be simple and I don't want to spend money on something used once.
Disclaimer: I'm a WebSphere ESB consultant for IBM.
The answer to your question depends on what you're expecting WebSphere ESB (WESB) to do for you. If you're simply trying to connect a Web Service consumer to a Web Service provider, you don't need need WESB to do that. However, typically folks want to use WESB because they either want to put some logic between the two (maybe transforming from one Web Service interface to another, for example), or because they might want to later. In either case, you'll need to create a mediation module to do that - there is no bus per se that you just connect services to.
In practice, you will need WebSphere Integration Developer (WID) to do that - it would be a lot of work to create the mediations manually, it's not documented, and it's not supported by IBM either. Your local IBM client team should be able to advise you, but these products are typically purchased together.
Hope that helps.