A bit off-topic : Recently started wondering what would be the preferred language to code some general "web service plumbing" tool : quickly generate client to

A bit off-topic : Recently started wondering what would be the preferred language to code some general "web service plumbing" tool : quickly generate client to access a web api, as well as easily provide data mapping and data "passing" from endpoints to endpoints. I started investigating language that would let you create DSLs, but i'm wondering if this field hasn't already been explored, and some tools created for that purpose.