weblog d’un abbe

20061013

If you’re a Google Apps for Your Domain user…

Filed under: Research — abbe @ 0058

If you’re a Google Apps for Your Domain user then, there are 99% chances that you can’t interoperate with non-Google Jabber users. Why ? In Jabber technology (or precisely XMPP protocol), user of one server can IM to user of another server. e.g. The process that takes when wahjava@gmail.com wants to talk to wahjava@jabber.org is illustrated below:

  1. Client of wahjava@gmail.com sends message destined to wahjava@jabber.org to gmail.com jabber server i.e. talk.google.com server.
  2. talk.google.com then starts search for the jabber server handling jabber.org domain. It first performs a DNS query for SRV record of _xmpp-server._tcp.jabber.org domain name. It recieves 30 30 5269 jabber.org. (as of now). Now from this reply, it deduces that jabber.org is the jabber server handling jaber.org domain.
  3. It then sends this message to jabber.org jabber server.
  4. From jabber.org jabber server, the message gets delivered to wahjava@jabber.org.

Now if wahjava@jabber.org wants to talk to wahjava@jnoiyunrn027n47jlsu.com (a Google Apps for Your Domain user), then 99% of chances are that he can’t. Why ? Because there is no SRV record for XMPP service (i.e. SRV record corresponding to _xmpp-server._tcp.jnoiyunrn027n47jlsu.com) present in the domain nameserver of jnoiyunrn027n47jlsu.com domain. So if wahjava@jnoiyunrn027n47jlsu.com wants to enable Jabber service (provided by Google Apps for Your Domain) fully, he needs to add a SRV record in domain nameserver of jnoiyunrn027n47jlsu.com.

This is neither mentioned in any of Google’s FAQ for Google Apps for Your Domain. I found this after failing to inviting one of my friend (who is a Google Apps for Your Domain user) to a Jabber conference hosted at jabber.org. Thanks to users at jabber channel jdev in jabber.org server for explaining me how Jabber server discovery for a domain takes place (which prevented me from looking into its RFCs ;)).

If no matching SRV record is found then the IP address pointed by A record (and probably AAAA record too, though I’m not sure on this) of domain name is probed for Jabber service.

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2 Comments »

  1. आप ऐसा क्यों नहीं करते कि इसकी जांच अपने जैबर के जरिये हमसे करें यह डोमेन गूगल एप्लीकेशन फॉर युअर डोमेन से युक्त है मेल पता ऊपर लिख दिया गया है जैसे ही wahjava@jabber.org संदेश देगा पता चल जाएगा।
    वैसे हमने जांच की भी है और ऐसा कुछ नहीं पाया है shree@amessage.info pushkarna@jabber.org से जो कि पूर्णतः जैबर सर्वर हैं से सहजता से वार्ता होती है वह भी किसी भी ओर से प्रारंभ की जाए यह लिखने से पहले पुनः जांच कर ली गई है
    अब ऐसा कैसे होता है आप तो समझ ही गए होंगे pushkarna.com के srv records को देख सकते हैं dnsreport stuff से

    श्री shree
    http://pushkarna.com

    Comment by shree — 20061126 @ 0115

  2. जांच करने पर पाया कि pushkarna.com server के SRV records ठीक हैं ।

    — begin dns stuff —
    _xmpp-server._tcp.pushkarna.com. 3600 IN SRV 5 0 5269 talk.l.google.com.
    _xmpp-server._tcp.pushkarna.com. 3600 IN SRV 20 0 5269 talk1.l.google.com.
    _xmpp-server._tcp.pushkarna.com. 3600 IN SRV 20 0 5269 talk2.l.google.com.
    _jabber._tcp.pushkarna.com. 3600 IN SRV 5 0 5222 talk.l.google.com.
    _jabber._tcp.pushkarna.com. 3600 IN SRV 20 0 5222 talk1.l.google.com.
    _jabber._tcp.pushkarna.com. 3600 IN SRV 20 0 5222 talk2.l.google.com.
    _xmpp-client._tcp.pushkarna.com. 3600 IN SRV 20 0 5222 talk4.l.google.com.
    _xmpp-client._tcp.pushkarna.com. 3600 IN SRV 5 0 5222 talk.l.google.com.
    _xmpp-client._tcp.pushkarna.com. 3600 IN SRV 20 0 5222 talk1.l.google.com.
    _xmpp-client._tcp.pushkarna.com. 3600 IN SRV 20 0 5222 talk2.l.google.com.
    _xmpp-client._tcp.pushkarna.com. 3600 IN SRV 20 0 5222 talk3.l.google.com.
    — end dns stuff —

    BtW, Google ने भी अब इसे अपने FAQ में address कर दिया है, निम्नलिखित URL पर:
    http://www.google.com/support/a/bin/answer.py?answer=34143&topic=9201

    परन्तु उन्होंने अभी तक _xmpp-client.tcp SRV record को include नहीं किया जोकि clients द्वारा server की खोज के लिए refer किया जाता है ।

    धन्यवाद
    आशीष शुक्ल

    Comment by आशीष शुक्ल — 20061126 @ 1131


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