Web Transport and Services

Quick Links: Web Services - HTTP Bridge - Transport Endpoints

Crossbar.io includes a full-featured WAMP router to wire up your application components. But if you serve HTML5 Web clients from Crossbar.io, the static Web assets for your frontends like HTML, JavaScript and image files need to be hosted somewhere as well.

You can host static content on your existing Web server or a static hosting service like Amazon S3. It does not matter if your Crossbar.io nodes reside on different domain names from the static content. However, you can let Crossbar.io also host the static assets. This is possible by using a Web Transport with your router.

Besides hosting static content, the Web Transport also adds a whole number of other features like serving WSGI, redirection, file upload or CGI.

Configuration

A Web transport is configured as a dictionary element in the list of transports of a router (see: Router Configuration ). The Web transport dictionary has the following configuration parameters:

attribute	description
id	The (optional) transport ID - this must be unique within the router this transport runs in (default: “transportN” - where N is numbered starting with 1)
type	Must be “web” (required)
endpoint	The endpoint to listen on (required). See Transport Endpoints
paths	A dictionary for configuring services on subpaths (required - see below and Web Services or HTTP Bridge ).
options	Is an optional dictionary for additional transport wide configuration (see below).

For Web transport paths the following two requirements must be fullfilled:

• a path must match the regular expression ^([a-z0-9A-Z_\-]+|/)$

• there must be a root path / set

The value mapped to in the paths dictionary is a Web Service. The complete list of available Web services can be found here:

• Web Services

• HTTP Bridge

The Web transport options can have the following attributes:

attribute	description
access_log	set to true to enable Web access logging (default: false)
display_tracebacks	set to true to enable rendering of Python tracebacks (default: false)
hsts	set to true to enable HTTP Strict Transport Security (HSTS) (only applicable when using a TLS endpoint) (default: false)
hsts_max_age	for HSTS, use this maximum age (only applicable when using a TLS endpoint). (default: 31536000)
options	Is an optional dictionary for additional transport wide configuration (see below).

Example

Here is the basic outline of a Web Transport configuration

{
   "controller": {
   },
   "workers": [
      {
         "type": "router",
         "transports": [
            {
               "type": "web",
               "endpoint": {
                  "type": "tcp",
                  "port": 8080
               },
               "paths": {
                  "/": {
                     "type": "static",
                     "directory": ".."
                  },
                  "ws": {
                     "type": "websocket"
                  }
               }
            }
         ]
      }
   ]
}

Here is an example that combines three services:

"paths": {
   "/": {
      "type": "static",
      "directory": ".."
   },
   "ws": {
      "type": "websocket",
   },
   "downloads": {
      "type": "static",
      "directory": "/home/someone/downloads"
   },
   "config": {
      "type": "json",
      "value": {
         "param1": "foobar",
         "param2": [1, 2, 3]
      }
   }
}