WSDL

now time for wsdl!

WSDL

web services description language

what does wsdl do

captures the type signatures of the methods available on a particular SOAP endpoint

wsdl 1

must work in an open environment where the payloads are essentially unknown

wsdl 2

a much more complex problem than most IDLs which work on a closed type universe

wsdl element 1

messages - the messages that can be invoked

wsdl element 2

port types - collections of messages

wsdl element 3

types - using xml schemata

wsdl element 4

bindings - the messages and transport protocols usable on each endpoint

port type 1

one way operations receive a message and never respond with one

port type 2

request response operations are normal RPC operations that accept a request message and generate a response

bindings

bind port types to endpoints

four styles of binding

document or RPC, literal or encoded

rpc literal

the name of the operations and parameters are the same, the data appears “literally”

document literal

no operation name, we just pass a document with the right elements in it

why rpc literal?

it is as simple as SOAP gets

why document literal?

allows pretty much arbitrary xml to be used to invoke operations, we extract data from the elements and use namespaces to remove ambiguity