Ethan Cerami's book Web Services Essentials
is exactly that - but not just an overview and introduction to the
concepts of Web Services and some of the key standards; but also a
(read open source) based programming introduction -where users get
to develop real, working Web Services.
Cerami starts with an overview of why XML fits well into the world
of distributed messaging and calls- XML's extensible tags are
almost perfect for the task. Then XML-RPC is defined and its relation
to SOAP(Simple Object Access Protocol) is defined for use in a sample
exercise using Apache SOAP. The exercise is simple message passing but
it does invoke a Web Service on the NET. The next phase involves learning
WSDL-Web Services Desscription Language which describes a Web Service
such that any user can go to a UDDI-Universal Description, Discovery
and Integration is a registry or database of WSDL descriptors to find
Web Services available and of interest. And Cerami shows how to setup
this up such that all of the UDDI querying is done in automated fashion
over the Web.
In short order, readers find they have read (and if so inclined, programmed)all
the ingredients of basic Web Services. Its all in the title of the
book - Web Services Essentials.