jsonrpc-c (client) Module

Matthew Williams

   <matthew@flowroute.com>

Edited by

Jordan Levy

   <jordan@flowroute.com>

   Copyright © 2011 Flowroute LLC (flowroute.com)
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. servers (string)
              3.2. max_conn_attempts (int)

        4. Functions

              4.1. jsonrpc_notification(method, parameters)
              4.2. jsonrpc_request(method, parameters, return_route,
                      error_route, result_var)

   List of Examples

   1.1. Set servers parameter
   1.2. Set max_conn_attempts parameter
   1.3. jsonrpc_notification usage
   1.4. jsonrpc_request usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. servers (string)
        3.2. max_conn_attempts (int)

   4. Functions

        4.1. jsonrpc_notification(method, parameters)
        4.2. jsonrpc_request(method, parameters, return_route,
                error_route, result_var)

1. Overview

   This module provides access to json-rpc services (operating over
   TCP/Netstrings).

   This module uses t_suspend() and t_continue() from the TM module.

   Note that after invoking an asyncronous operation, the processing will
   continue later, in another application process. Therefore, do not rely
   on variables stored in private memory, use shared memory if you want to
   get values after the processing is resumend (e.g., $shv(...) or htable
   $sht(...)).

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * tm - transaction management.

2.2. External Libraries or Applications

   Note: this module uses Linux specific API, part of glibc library, it
   might not compile on other types of operating systems.

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * libjson (https://github.com/json-c/json-c/wiki)
     * libevent - http://libevent.org/
     * glibc - http://www.gnu.org/software/libc/ (v2.8 or higher)

3. Parameters

   3.1. servers (string)
   3.2. max_conn_attempts (int)

3.1. servers (string)

   The servers providing the remote jsonrpc service. Format is
   "host1:port1,priority1 host2:port2,priority2". Requests to servers of
   the same priority will be distributed evenly (round robin). Server
   groups with higher priority are used first.

   Example 1.1. Set servers parameter
...
modparam("jsonrpc", "servers", "localhost:9999,2 10.10.0.1:9999,2 backup.server:
9999,1")
...

3.2. max_conn_attempts (int)

   Max number of connection attempts for a server. -1 will keep
   reconnecting forever, 0 will skip any attempt to reconnect.

   Example 1.2. Set max_conn_attempts parameter
...
modparam("jsonrpc", "max_conn_attempts", 10)
...

4. Functions

   4.1. jsonrpc_notification(method, parameters)
   4.2. jsonrpc_request(method, parameters, return_route, error_route,
          result_var)

4.1.  jsonrpc_notification(method, parameters)

   Invokes the remote 'method' with the given 'parameters' as a
   notification. Unlike jsonrpc_request (below), notifications do not
   receive a response. Script processing continues in the usual fashion as
   soon as the notification has been sent.

   The method and parameters can be a static string or dynamic string
   value with config variables.

   Example 1.3. jsonrpc_notification usage
...
jsonrpc_notification("update_user", "{'id': 1234, 'name': 'Petros'}")
...

4.2.  jsonrpc_request(method, parameters, return_route, error_route,
result_var)

   Invokes the remote 'method' with the given 'parameters'. When the
   response is received, continues processing of the SIP request with the
   route[return_route]. If a timeout occurs, no servers can be reached, or
   a jsonrpc error message is received, continues process at
   route[error_route]. In this case, the result_var will contain one of
   "timeout", "failure", or the error message received back from the
   jsonrpc server.

   The method, parameters, return_route, and error_route can be a static
   string or a dynamic string value with config variables.

   Since the SIP request handling is resumed in another process, the
   config file execution is lost. As mentioned above, only shared
   variables ($shv, etc) should be used for any value that will be needed
   when the script is resumed.

   The result is stored in the pseudo-variable 'result_var'. Since this
   variable is set after the response is received, it is possible to use a
   $var for this parameter.

   Example 1.4. jsonrpc_request usage
...
jsonrpc_request("get_user", "{'id': 1234}", "RESPONSE", "ERROR", "$var(result)")
;
...
route[RESPONSE] {
        xlog("Result received: $var(result)");
        ...
}
...
route[ERROR] {
        xlog("Error received: $var(result)");
        ...
}
...
