[Serusers] Summary of using SER as an app server

[Michael Shuler]

SER works much better as a proxy in front of an app server such as Asterisk.
Asterisk will need the following patch to truly be useful
http://svn.asteriskdocs.org/res_data/

----------------------------------------

Michael Shuler, C.E.O.
BitWise Communications, Inc. (CLEC) And BitWise Systems, Inc. (ISP)
682 High Point Lane
East Peoria, IL 61611
Office: (217) 585-0357
Cell: (309) 657-6365
Fax: (309) 213-3500
E-Mail: mike at bwsys.net
Customer Service: (877) 976-0711 

> -----Original Message-----
> From: serusers-bounces at lists.iptel.org 
> [mailto:serusers-bounces at lists.iptel.org] On Behalf Of Franklin, Allen
> Sent: Monday, October 04, 2004 5:51 PM
> To: serusers at lists.iptel.org
> Subject: [Serusers] Summary of using SER as an app server
> 
> 
> I have been trying to figure out if I can use the SER server 
> as a true app server.
> I have summarized my findings, below.
> The findings are quite terse (I'm writing it for my 
> superiors) and may sound a little
> harsh, but that's not my intent. I am just hoping to generate 
> some discussion.
> 
> 
> 
> 
> Summary of using SER as an app server:
> 
> Controlling SER using scripts
> -----------------------------
> Routing scripts can be written by a user.
> Only a single script is processed by the engine.
> The SER server hands every SIP message it receives to the 
> script processing engine.
> The script may add/remove/modify header fields and then tell 
> SER what to do with the result.
> The script always operates on the "current" SIP message.
> The scripts must be written in a SER-developed language.
> The language provides operators and functions for 
> manipulating string values in SIP headers.
> The language provides routing functions like forward() and t_relay(). 
> The script engine provides hooks to allow a script to execute 
> shell commands.
> A very basic hook is provided that allows a script to call 
> functions in a user-provided shared library,
> but this hook is only useful for rewriting the URI of the 
> "current" message.
> 
> Controlling SER through an external process
> -------------------------------------------
> The SER server provides an interface to its internal 
> functions via its "Application FIFO Server".
> The IPC mechanism employed is a pair of fifos (or files).
> There is a set of defined FIFO commands that the app can send to SER.
> There is only 1 FIFO command for initiating a transaction 
> from an external process: t_uac() (also t_uac_dlg()).
> The app blocks on a fifo read until the server matches up a 
> reply from the last command sent,
> the complete message text is returned in the read. Presumably 
> SER will handle retransmissions.
> 
> SER does not allow scripts or app server processes to see or 
> modify the SDP, so an app
> server process could not be used to initiate a voice call.
> 
> SER does not have a SIP parser as would be found in a 
> traditional SIP stack.
> 
> _______________________________________________
> Serusers mailing list
> serusers at lists.iptel.org
> http://lists.iptel.org/mailman/listinfo/serusers
>