wsme/doc/integrate.rst

Integrating with a Framework

General considerations

Using WSME within another framework providing its own REST capabilities is generally done by using a specific decorator to declare the function signature, in addition to the framework's own way of declaring exposed functions.

This decorator can have two different names depending on the adapter.

@wsexpose

This decorator will declare the function signature and take care of calling the adequate decorators of the framework.

Generally this decorator is provided for frameworks that use object-dispatch controllers, such as adapter-pecan and adapter-tg1.

@signature

This decorator only sets the function signature and returns a function that can be used by the host framework as a REST request target.

Generally this decorator is provided for frameworks that expect functions taking a request object as a single parameter and returning a response object. This is the case for adapter-cornice and adapter-flask.

If you want to enable additional protocols, you will need to mount a WSRoot instance somewhere in the application, generally /ws. This subpath will then handle the additional protocols. In a future version, a WSGI middleware will probably play this role.

Note

Not all the adapters are at the same level of maturity.

WSGI Application

The wsme.WSRoot.wsgiapp function of WSRoot returns a WSGI application.

Example

The following example assumes the REST protocol will be entirely handled by WSME, which is the case if you write a WSME standalone application.

from wsme import WSRoot, expose


class MyRoot(WSRoot):
    @expose(unicode)
    def helloworld(self):
        return u"Hello World !"

root = MyRoot(protocols=['restjson'])
application = root.wsgiapp()

Cornice

" Cornice provides helpers to build & document REST-ish Web Services with Pyramid, with decent default behaviors. It takes care of following the HTTP specification in an automated way where possible."

wsmeext.cornice -- Cornice adapter

wsmeext.cornice

signature

Declare the parameters of a function and returns a function suitable for cornice (ie that takes a request and returns a response).

Example

from cornice import Service
from wsmeext.cornice import signature
import wsme.types

hello = Service(name='hello', path='/', description="Simplest app")

class Info(wsme.types.Base):
    message = wsme.types.text


@hello.get()
@signature(Info)
def get_info():
    """Returns Hello in JSON or XML."""
    return Info(message='Hello World')


@hello.post()
@signature(None, Info)
def set_info(info):
    print("Got a message: %s" % info.message)

Flask

"Flask is a microframework for Python based on Werkzeug, Jinja 2 and good intentions. And before you ask: It's BSD licensed! "

Warning

Flask support is limited to function signature handling. It does not support additional protocols. This is a temporary limitation, if you have needs on that matter please tell us at python-wsme@googlegroups.com.

wsmeext.flask -- Flask adapter

wsmeext.flask

signature(return_type, *arg_types, **options)

See @signature for parameters documentation.

Can be used on a function before routing it with flask.

Example

from wsmeext.flask import signature

@app.route('/multiply')
@signature(int, int, int)
def multiply(a, b):
    return a * b

Pecan

"Pecan was created to fill a void in the Python web-framework world – a very lightweight framework that provides object-dispatch style routing. Pecan does not aim to be a "full stack" framework, and therefore includes no out of the box support for things like sessions or databases. Pecan instead focuses on HTTP itself."

Warning

A pecan application is not able to mount another WSGI application on a subpath. For that reason, additional protocols are not supported for now, until WSME provides a middleware that can do the same as a mounted WSRoot.

wsmeext.pecan -- Pecan adapter

wsmeext.pecan

wsexpose(return_type, *arg_types, **options)

See @signature for parameters documentation.

Can be used on any function of a pecan RestController instead of the expose decorator from Pecan.

Configuration

WSME can be configured through the application configation, by adding a 'wsme' configuration entry in config.py:

wsme = {
    'debug': True
}

Valid configuration variables are :

• 'debug': Whether or not to include exception tracebacks in the returned server-side errors.

Example

The example from the Pecan documentation becomes:

from wsmeext.pecan import wsexpose

class BooksController(RestController):
    @wsexpose(Book, int, int)
    def get(self, author_id, id):
        # ..

    @wsexpose(Book, int, int, body=Book)
    def put(self, author_id, id, book):
        # ..

class AuthorsController(RestController):
        books = BooksController()

Turbogears 1.x

The TG adapters have an api very similar to TGWebServices. Migrating from it should be straightforward (a little howto migrate would not hurt though, and it will be written as soon as possible).

wsmeext.tg11 -- TG 1.1 adapter

wsmeext.tg11

wsexpose(return_type, *arg_types, **options)

See @signature for parameters documentation.

Can be used on any function of a controller instead of the expose decorator from TG.

wsvalidate(*arg_types)

Set the argument types of an exposed function. This decorator is provided so that WSME is an almost drop-in replacement for TGWebServices. If starting from scratch you can use wsexpose only

adapt(wsroot)

Returns a TG1 controller instance that publish a wsme.WSRoot. It can then be mounted on a TG1 controller.

Because the adapt function modifies the cherrypy filters of the controller the 'webpath' of the WSRoot instance must be consistent with the path it will be mounted on.

wsmeext.tg15 -- TG 1.5 adapter

wsmeext.tg15

This adapter has the exact same api as wsmeext.tg11.

Example

In a freshly quickstarted tg1 application (let's say, wsmedemo), you can add REST-ish functions anywhere in your controller tree. Here directly on the root, in controllers.py:

# ...

# For tg 1.5, import from wsmeext.tg15 instead :
from wsmeext.tg11 import wsexpose, WSRoot

class Root(controllers.RootController):
    # Having a WSRoot on /ws is only required to enable additional
    # protocols. For REST-only services, it can be ignored.
    ws = adapt(
        WSRoot(webpath='/ws', protocols=['soap'])
    )

    @wsexpose(int, int, int)
    def multiply(self, a, b):
        return a * b

Other frameworks

Bottle

No adapter is provided yet but it should not be hard to write one, by taking example on the cornice adapter.

This example only show how to mount a WSRoot inside a bottle application.

import bottle
import wsme

class MyRoot(wsme.WSRoot):
    @wsme.expose(unicode)
    def helloworld(self):
        return u"Hello World !"

root = MyRoot(webpath='/ws', protocols=['restjson'])

bottle.mount('/ws', root.wsgiapp())
bottle.run()

Pyramid

The recommended way of using WSME inside Pyramid is to use adapter-cornice.