service registry

Hi ,

I come to know that whatever service exposed by any system is available in service registry or in other way u can say that whoever exposed service create an entry in service registry to inform outside world.

Actually i m try to consume some service that is exposed by any system i,e ERP q43 etc.

so i just waana know that where is the service registry and it is necessary that all the service exposed must present in service registry.

Thanks,

sudhanshu