kamailio/modules/xhttp

xHTTP Module

Daniel-Constantin Mierla



Edited by

Daniel-Constantin Mierla



Edited by

Alex Balashov



Copyright � 2010 asipto.com
__________________________________________________________________

Table of Contents

1. Admin Guide

1. Overview
2. Note on Latency
3. Dependencies

3.1. Kamailio Modules
3.2. Kamailio Core Settings
3.3. External Libraries or Applications

4. Parameters

4.1. url_skip (str)
4.2. url_match (str)

5. Functions

5.1. xhttp_reply(code, reason, ctype, body)

List of Examples

1.1. Set url_skip parameter
1.2. Set url_match parameter
1.3. xhttp_reply usage

Chapter 1. Admin Guide

Table of Contents

1. Overview
2. Note on Latency
3. Dependencies

3.1. Kamailio Modules
3.2. Kamailio Core Settings
3.3. External Libraries or Applications

4. Parameters

4.1. url_skip (str)
4.2. url_match (str)

5. Functions

5.1. xhttp_reply(code, reason, ctype, body)

1. Overview

This module provides basic HTTP/1.0 server functionality inside SIP
Router. SIP and HTTP are very similar protocols, so, practically, the
SIP parser can easily handle HTTP requests just by adding a fake Via
header.

The xmlrpc module uses the same concept. xHTTP module offers a generic
HTTP handling way, by calling event_route[xhttp:request] in your
config. You can check the HTTP URL via config variable $hu. Note that
use of $ru will raise errors since the structure of an HTTP URL is not
compatible with that of a SIP URI.

2. Note on Latency

Because HTTP requests in xhttp are handled by the same, finite number
of SIP worker processes that operate on SIP messages, the same general
principles regarding script execution speed and throughput should be
observed by the writer in event_route[xhttp:request] as in any other
part of the route script.

For example, if you initiate a database query in the HTTP request route
that takes a long time to return rows, the SIP worker process in which
the request is handled will be blocked for that time and unable to
process other SIP messages. In most typical installations, there are
only a few of these worker processes running.

Therefore, it is highly inadvisable to execute particularly slow things
in the event_route[xhttp:request], because the request is not handled
in an asynchronous manner or otherwise peripherally to general SIP
processing. SIP worker threads will block, pending the outcome of the
event route just like any other config script route.

This is no more or less true for xhttp than it is for any other block
of script in any other scenario, and does not warrant any extraordinary
concern. It nevertheless bears mention here because some processes with
embedded HTTP servers have the request processing take place "outside"
of the main synchronous event sequence, whether by creating separate
threads or by some other asynchronous handling. That is not the case
with xhttp.

3. Dependencies

3.1. Kamailio Modules
3.2. Kamailio Core Settings
3.3. External Libraries or Applications

3.1. Kamailio Modules

The following modules must be loaded before this module:
* sl - stateless reply.

3.2. Kamailio Core Settings

SIP requires a Content-Length header for TCP transport. But most HTTP
clients do not set the content length for normal GET requests.
Therefore, the core must be configured to allow incoming requests
without content length header:
* tcp_accept_no_cl=yes

3.3. External Libraries or Applications

The following libraries or applications must be installed before
running Kamailio with this module loaded:
* None

4. Parameters

4.1. url_skip (str)
4.2. url_match (str)

4.1. url_skip (str)

Regular expression to match the HTTP URL. If there is a match, then
event route is not executed.

Default value is null (don't skip).

Example 1.1. Set url_skip parameter
...
modparam("xhttp", "url_skip", "^/RPC2")
...

4.2. url_match (str)

Regular expression to match the HTTP URL. If there is no match, then
event route is not executed. This check is done after url_skip, so if
both url_skip and url_match would match then the event route is not
executed (url_skip has higher priority).

Default value is null (match everything).

Example 1.2. Set url_match parameter
...
modparam("xhttp", "url_match", "^/sip/")
...

5. Functions

5.1. xhttp_reply(code, reason, ctype, body)

5.1. xhttp_reply(code, reason, ctype, body)

Send back a reply with content-type and body.

Example 1.3. xhttp_reply usage
...
event_route[xhttp:request] {
xhttp_reply("200", "OK", "text/html",
"OK - [$si:$sp]");
}
...