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Northbound interface:RESTful

Revision as of 16:51, 23 November 2015 by Sylvain Fontaine (talk | contribs)

In computing, Representational State Transfer (REST) is the software architectural style of the World Wide Web. REST gives a coordinated set of constraints to the design of components in a distributed hypermedia system that can lead to a higher-performing and more maintainable architecture.

To the extent that systems conform to the constraints of REST they can be called RESTful. RESTful systems typically, but not always, communicate over HTTP with the same HTTP verbs (GET, POST, PUT, DELETE, etc.) which web browsers use to retrieve web pages and to send data to remote servers. REST interfaces with external systems using resources identified by URI, for example /people/tom, which can be operated upon using standard verbs, such as DELETE /people/tom.

Reference: Wikipedia

TelcoBridges RESTful Northbound Interface

As of Release 2.9, TelcoBridges gateways support a RESTful configuration interface using JSON for data exchange.

Supported RFCs

TelcoBridges supports the following RFCs for RESTful API:

Specification Supported
RFC 7159 The JavaScript Object Notation (JSON) Data Interchange Format Yes
Extensible Markup Language (XML) 1.0 (Fifth Edition) No
RFC 2617 HTTP Authentication: Basic and Digest Access Authentication Basic Scheme Only
RFC 2109 HTTP State Management Mechanism Yes

REST API overview

Supported Methods

GET

List collection entries

 GET /users
 <- Content : {"root":{}}
 <- Code    : HTTP/1.0 200 OK

Read a specific configuration entry

 GET /users/root
 <- Content : {"name":"root","user_group":"Admin","pass":"Not Shown"}
 <- Code    : HTTP/1.0 200 OK

PUT

Update a configuration entry

 PUT /users/root
 -> Content : {"pass":"MyNewSecret"}
 <- Code    : HTTP/1.0 200 OK

Omitted attributes in a PUT are left unchanged on the server.

POST

Create a configuration entry into a collection

 POST /users
 -> Content : { "name" : "RogerFluffy", "user_group" : "nobody" , "pass" : "xyz" }
 <- Code    : HTTP/1.0 200 OK

Omitted attributes in a POST are being set to 'default'.

DELETE

Delete a configuration entry from a collection

 DELETE /users/RogerFluffy
 <- Code    : HTTP/1.0 200 OK

Entries

Entries are found under collection URIs. A collection is generally composed of multiple entries, with a different name for each entry. The entry name must be provided during the POST:

 POST /users
 -> Content : { "name" : "RogerFluffy", ... }
 <- Code    : HTTP/1.0 200 OK

Entries generally have attributes, and can also include collections. For example, for the configuration entry MyCFG, we can find the routes collection using the following URI:

 /configurations/MyCFG/routes

Collections

URI with the plural form generally represent a collection of entries. A collection can be composed of mutiple entries, or limited to 1.

For example, the URI where users configuration entries are grouped into is

 /users

Likewise, the list of routes can be found on

 /configurations/MyCFG/routes

When the collection is limited to 1 entry, the entry name is fixed. For example, only one H.248 stack can be defined, therefore the name is fixed to gateway_h248 The entry name must be NOT be provided during the POST:

 POST /configurations/MyCFG/h248_stacks
 -> Content : { "enabled" : true, "naps" : [ "NAP_TDM", "RTP_NAP"], ... }
 <- Code    : HTTP/1.0 200 OK

Recursivity

Non-recursive (default) requests

By default, requests are non-recursive. This means that when a GET request is made on a URI, only objects on that element will be returned.

 GET /configurations/NewCFG
 <- Content : {"name":"NewCFG", "notes":"This is a new demo configuration", "routes":{}, ... }

In the response, we see two attribute value pairs : name and notes. One other object there is routes. These two are collections, and should be queried individually to get their sub-elements.

 GET /configurations/NewCFG/routes
 <- Content : {"Route1":{}, ...}
 GET /configurations/NewCFG/routes/Routes1
 <- Content : {"name":"Route1", "called":"5551212","calling":"", ...}

Recursive requests

It is possible to get all sub-elements from a GET by using the recursive=yes attribute on the URI.

 GET /configurations/NewCFG?recursive=yes
 <- Content : { 
      "name":"NewCFG", 
      "notes":"This is a new demo configuration", 
      "routes": { 
        "Route1": {
          "name":"Route1", 
          "called":"5551212",
          "calling":"", ...
        },
        "Route2": {
          "name":"Route2", 
          "called":"5551314",
          "calling":"", ...
        }, ...
      }
    }

This is also true to get the content of all elements of a collection

 GET /users?recursive=yes
 <- Content : {
      "RogerFluffy":{
        "name":"RogerFluffy",
        "user_group":"nobody",
        "pass":"Not Shown"
      },
      "root":{
        "name":"root",
        "user_group":"Admin",
        "pass":"Not Shown"
      }
    }

Request Status code

The following result class are used to as HTTP status code to indicate the result of request.

* 2XX - success
* 3XX - redirection (304 Not Modified)
* 4XX - client error
* 5XX - server error

In Addition to HTTP status code, every HTTP response also inlcudes a JSON payload with a verbose message.

 POST /configurations/MyCFG/h248_stacks
 -> Content : { ... }
 <- Code    : HTTP/1.0 200 OK
 <- Content : { "message" : "Tbgw h248 cfg creation failed: Public ip address can't be blank, Public ip address is invalid, Local ip address is invalid, Local ip address When not using virtual ip, an ip address must be entered"}

This message can be used to find the exact reason why a RESTful API call failed.

HTTP headers

The following HTTP header should be used in requests:

HTTP Header Description
Host Mandatory
Authorization RFC2617 WWW Authentication, basic mode. Can be used on each requests, or first request only by using Cookie/Set-Cookie headers
Cookie RFC2109 HTTP Session management
Content-Type "application/json; charset=utf-8"
Content-Length Length of content for PUT and POST requests
User-Agent Optional
If-None-Match Optional (HTTP ETag/If-None-Match caching mechanism)
Cache-Control HTTP Cache control, use is optional
Connection "keep-alive"

The following HTTP header are to be expected for a server response:

HTTP Header Description
Authorization RFC2617 WWW Authentication
Set-Cookie RFC2109 HTTP Session management
Content-Type "application/json; charset=utf-8"
Content-Length Length of content
E-Tag Optional (HTTP ETag/If-None-Match caching mechanism)
Cache-Control Optional
Date Can be ignored
X-Runtime Can be ignored
X-Frame-Option To be ignored

API Access

HTTP port

The HTTP port for RESTful access is the same as for the Web interface. By default, the port is 12358.

Credentials

The credentials (user/password) used to authenticate a RESTful client application are the same as for the WebPortal. Users can be managed from the Web interface under /users. The same path is used to manage users by the RESTful interface.