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Java Programming

SIP: Creating Next-Generation Telecom Applications 18

Posted by michael from the fun-with-java dept.
An anonymous reader writes "In this article, you'll discover how the Session Initiation Protocol (SIP) operates and, building on that knowledge, you will learn how to use the Java SIP Servlet API to build new applications that can run on telecommunications networks. The SIP tour concludes with code examples that demonstrate SIP application development in action."
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SIP: Creating Next-Generation Telecom Applications More

SIP: Creating Next-Generation Telecom Applications

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  • When all you have is a hammer.... (Score:2, Insightful)

    by Anonymous Coward
    Excellent! A derivative of a non-real time, bulk data transfer protocol family (SMTP, HTTP) being used for real time signalling applications.

    While the HTTP request/response model has served the IETF well enough for many things, perhaps they should consider more protocol models than the single hammer they seem to have equipped their toolbox with.
    • First, IETF does not really control the standards. The standard committees and the working groups do. If a working group prefers HTTP request/response then so be it.

      Second, SIP was developed when HTTP request/response seemed like the new way of doing a lot of stuff. It has disadvantages (verbose, textual, lot of cruft you don't need) and advantages (already specified, clear way of extending it, MIME support)

      Third, SIP and other protocols used/specified by the telecom industry tend to have layer upon layer
      • SIP and other protocols used/specified by the telecom industry tend to have layer upon layer. If 1 layer is good, then 10 layers must be ten times as good.

        Huh? Last time I checked, the major alternatives were SIP and H.323. H.323, not SIP, is the overspecified, layered monster from the telecom industry. (Although I'm sure SIP sucks, too.)
    • Did you even read enough of the article to see what SIP does? SIP uses RTP for the media trafic ("real time applications"). Using a "bulk data transfer" for call signaling seems quite appropriate to me. How quickly do you really need your phone to start ringing?

      Also notice that SOAP uses HTTP for RPC. HTTP is hardly bulk anymore.

      • How quickly do you really need your phone to start ringing?

        SIP devices start ringing before their bearer (RTP) is connected (i.e. 180 Ringing is before RTP stream gets set up). In contrast, a black phone (regular telephone) won't start ringing (alerting) until the bearer is connected. This has usability issues, because people are used to the way that regular telephones operate. If the bearer fails on a SIP phone, the phone call can still connect (i.e. the signalling worked), which can confuse both users.

  • Yes... (Score:4, Interesting)

    by 4of12 ( 97621 ) on Friday October 03, 2003 @12:22PM (#7124785) Homepage Journal

    Another great contribution to providing free public documentation by IBM. Kudoes to them.

    Meanwhile, there's that oncoming train [techweb.com] about states requiring VoIP providers to become fully bureaucratically functional telephone providers....

    A good dose of well-meaning out-dated regulation ought to slow down the adoption rate of good new technology.

  • How SIP operates...? (Score:1, Insightful)

    by Anonymous Coward
    I am not sure if that article really explains how SIP operates as much as the Java API the article refers to operates.

    For instance, it does not get into SIP message forking, spiralling, and time outs, nor does it explain how the ACK (the only request which does not get a response) is sometimes considered part of the INVITE transaction, and sometimes it is not, nor how authentication works, or message encryption.

    No mention of the use and differences between CANCEL and BYE.

    There appears to be only a brief
  • Jabber protocol seems conceptually very close (user agent talking to server, server talking to server, server taling to other UA) but Jabber IMHO is somewhat better organized (more XMLish).

    Anyone has opinions on that?

    • Re:how does SIP compare to Jabber? (Score:1, Interesting)

      by Anonymous Coward
      Total agreement. Jabber at least has a consistant, simpler set of syntax and parsing rules, and is more willing to bend on the 'dumb core, smart edge' obsession that besets SIP to the point of idiocy.

    • Re:how does SIP compare to Jabber? (Score:1, Informative)

      by Anonymous Coward
      Here's [blat.info] some more info about SIP.

    • Re:how does SIP compare to Jabber? (Score:1, Informative)

      by Anonymous Coward
      Isn't Jabber using the H.323 protocol for session initiation? Jabber as a whole is much biger protocol than SIP so there's no point to compare them.
      It's common misunderstanding. SIP is only for session initiation. For content exchange You have SDP protocol for example, which very often comes together with SIP.
      • Isn't Jabber using the H.323 protocol for session initiation?

        Where did you get this crazy misunderstanding? Jabber uses XMMP, which is lightweight protocol. Well, jabber uses H.323 - but only for voice over IP extensions/applications, not for regular sessionmanagement.

        Who is the idiot that modded up the parent as "informative"? Check the "information" before you rate it!

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