The function ws-start takes takes two arguments handlers
and port. It starts a server listening on port
responding to requests with handlers. Handlers may be
either a single function or an association list composed of pairs of
matchers and handler functions. When handlers is a single
function the given function is used to serve every request, when it is
an association list, the function of the first matcher to match each
request handles that request.
Matchers may be a regular expression or a function. Regular
expression matchers consists of an HTTP header and a regular
expression. When the regular expression matches the content of the
given header the matcher succeeds and the associated handler is
called. For example the following matches any GET request
whose path starts with the substring “foo”.
(:GET . "^foo")
A function matcher is a function which takes the request object (see Requests) and succeeds when the function returns a non-nil value. For example the following matcher matches every request,
(lambda (_) t)
and the following matches only requests in which the supplied “number” parameter is odd.
(lambda (request) (oddp (string-to-number (cdr (assoc "number" request)))))
Each handler is a function which takes a request object
(see Requests) as its only argument. The function may respond to
the request by writing to the network process held in the
process field of the request object. For example, the
process-send-string function may be used to write string data
to a request as in the following.
(process-send-string (process request) "hello world")
When the handler function exits the connection is terminated unless
the handler function returns the keyword :keep-alive.