Availability:
:- use_module(library(http/http_dispatch)).
[det]http_handler(+Path,
:Closure, +Options)'/home.html' or a term
Alias(Relative). Where Alias is associated with a concrete path using http:location/3
and resolved using http_absolute_location/3. Relative
can be a single atom or a term‘Segment1/Segment2/...`, where each
element is either an atom or a variable. If a segment is a variable it
matches any segment and the binding may be passed to the closure. If the
last segment is a variable it may match multiple segments. This allows
registering REST paths, for example:
:- http_handler(root(user/User), user(Method, User),
[ method(Method),
methods([get,post,put])
]).
user(get, User, Request) :-
...
user(post, User, Request) :-
...
If an HTTP request arrives at the server that matches Path, Closure is called as below, where Request is the parsed HTTP request.
call(Closure, Request)
Options is a list containing the following options:
- authentication(+Type)
- Demand authentication. Authentication methods are plugable. The library
http_authenticate.plprovides a plugin for user/password basedBasicHTTP authentication. - chunked
- Use
Transfer-encoding: chunkedif the client allows for it. - condition(:Goal)
- If present, the handler is ignored if Goal does not succeed.
- content_type(+Term)
- Specifies the content-type of the reply. This value is currently not used by this library. It enhances the reflexive capabilities of this library through http_current_handler/3.
- id(+Atom)
- Identifier of the handler. The default identifier is the predicate name. Used by http_location_by_id/2 and http_link_to_id/3.
- hide_children(+Bool)
- If
trueon a prefix-handler (see prefix), possible children are masked. This can be used to (temporary) overrule part of the tree. - method(+Method)
- Declare that the handler processes Method. This is equivalent
to
methods([Method]). Usingmethod(*)allows for all methods. - methods(+ListOfMethods)
- Declare that the handler processes all of the given methods. If this option appears multiple times, the methods are combined.
- prefix
- Call Pred on any location that is a specialisation of Path.
If multiple handlers match, the one with the longest path is used.
Options defined with a prefix handler are the default options
for paths that start with this prefix. Note that the handler acts as a
fallback handler for the tree below it:
:- http_handler(/, http_404([index('index.html')]), [spawn(my_pool),prefix]). - priority(+Integer)
- If two handlers handle the same path, the one with the highest priority is used. If equal, the last registered is used. Please be aware that the order of clauses in multifile predicates can change due to reloading files. The default priority is 0 (zero).
- spawn(+SpawnOptions)
- Run the handler in a separate thread. If SpawnOptions is an atom, it is interpreted as a thread pool name (see create_thread_pool/3). Otherwise the options are passed to http_spawn/2 and from there to thread_create/3. These options are typically used to set the stack limits.
- time_limit(+Spec)
- One of
infinite,defaultor a positive number (seconds). Ifdefault, the value from the settinghttp:time_limitis taken. The default of this setting is 300 (5 minutes). See setting/2.
Note that http_handler/3 is normally invoked as a directive and processed using term-expansion. Using term-expansion ensures proper update through make/0 when the specification is modified.