Subject: [SIP] Re: About "The SIP servlet API"

From: S_S_Dinesh/India/[email-masked]
Date: Mon, 8 May 2000 14:10:18 +0530

Hi,

The "SIP Servelet API" and "Building a SIP Stack" are two very different
things.

If you want to build a SIP Stack, which can be used in many softwares as
you say, you are looking at a generic stack that can
be used to build UAs, Proxies, Redirects etc. In which case, you should not
be bulding a SIP Servelet API only - this document models itself to the
usual Web Server-  Sevelet interface and focusses prmarily on Java, and for
a specific intention - deferring SIP controls to Java classes as 'SIP
Servelets'

Again, thats harldy building a stack to suit all applications.
Of course, you could derive APIs from it if you so wish, but the bottom
line is what you want to do (build a generic sip stack) and what the
servelet API propses are two different things.

If your friend wants a servelet interface, and you think the servelet API
draft suits you, sure you could implement it, but again, it does
not *replace* a generic SIP stack, it would add on to it.

Why dont you look at
http://www.cs.columbia.edu/~hgs/sip/implementations.html   - there are
companies that have implemented generic stacks, and some of their links
(follow it from the implementations page) give you an idea of expected
features from a generic SIP Stack

Regds
Arjun

--
Arjun Roychowdhury @ Hughes Software Systems

"yinshaohua" <[email-masked]> on 03/14/2000 01:02:09 PM

Please respond to "yinshaohua" <[email-masked]>

To:   [email-masked]
cc:

Subject:  About "The SIP servlet API"

Hi :
    Now I have a discussion with my fellow, would you give some suggestions
?
    We want to make a SIP Stack which can be used in many softwares. My
fellow consider that the SIP Stack will be realized providing that it
presents the API of the draft " The SIP Servlet API". But I have some
questions about the API:
    A. When using in sip server,the servlet dispaly less role: decode the
SIP message and the decoded header can be reached by server , store the
trasaction (call-id, to etc), create
message and may set some values according to the
transaction,retransmissions. In section 5.3 of the draft, there writes "
These headers (call-id, from,to,cseq) should not need to be manipulated
directly by servlets ",  I think A SIP stack SHOULD complete essential sip
call management and process some parameters, sending only the useful
infomation for service but not all parameters of message to other module.
    B. As a module of a software, the provided API is so many that it can
be
said the module is not encapsulated. So it not benefit to software
maintenance. I think a SIP stack only gives a series of abstract API which
can be used by other module to complete the service stipulated by the
protocol
    C. Due to so many API, it is difficult to replant a servlet to other
use, meanwhile, the
servlet is diffcult to maintain because it have not a legible limit with
other module.
    D. The SIP STACK should guarantee the SIP message sent by it accord
with
SIP protocol, but the servlet will not due to offering the API.So there may
send unlawful message when the servlet use in other software.
    Please give some suggestions. Thanks!

Shaohua Yin

2000/3/10

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