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I am fairly new to the presence server thing. I have got the idea about how the presence server works, concept like presentity, watcher , PUBLISH, SUBSCRIBE, NOTIFY, SIP transactions.

I have to work on a project prototype where we have the Presence Server database exposed as SaaS using REST.

One thing I am not able to find out is, the presence data or the information about the publisher and subscriber is stored in the Database tables or in the XML files. Because as I read, everywhere they say about XCAP server which has the policy documents and this policy documents are applied on publisher and subscribers document which are also in xml. I am wondering what is in database then?

Q. So, is it like the information is stored in tables and then converted to xml?

Q. Can we have all the information in tables and can we let go of the XCAP server.

I am desperately looking for the answer.

Thanks

user3275095
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1 Answers1

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http://openxcap.org/ - Image

The following image can be used as a reference to define what is achieved by the XCAP server. It provides HTTP Access to clients to access rules and profiles corresponding to the user and preferences that is available in the DB. So it a direct interface to the DB and is needed if you are going to provide access over REST

Image courtesy - http://openxcap.org/

Rajesh
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  • Thanks Rajesh. But still not clear to me. May be you can elaborate. Or if possible mention steps for a PUBLISH flow. – user3275095 Oct 21 '14 at 18:17
  • I hope this helps - http://www.cs.columbia.edu/~vs2140/presence/presence_simplified.pdf – Rajesh Oct 21 '14 at 19:37
  • Thanks. Thats a good document which I had read already. I have idea of those policy docs, filtering etc. But again my basic confusion about XCAP and Database remains. In this doc also, in some slides (39, 40) it shows presence database and no XCAP but in the next few slides it talks of XCAP but no database. That's why the confusion. Are both the terms used interchangeably? Is there no database as such and only XCAP server? And if there are both then what's there in database? These are my basic doubts. – user3275095 Oct 22 '14 at 13:32
  • How i have understood the difference is that the DB is the repository for all users, preferences and notification status both for watcher and Notifiers and has everything related to the SIP Server interacting to hold Subscriber Information. The XCAP is the direct interface for the client [BOB] to these policies without having to burden a SIP Server which is its only Signalling Interface. There are not many interfaces or SIP Messaging that could get the user to access the very same information from the DB. Thats the reason in some flows where its not relevant the XCAP is skipped. – Rajesh Oct 22 '14 at 17:20
  • Thanks Rajesh. I think it is also the case of the design the server is using. Each server may be following different design. – user3275095 Oct 23 '14 at 13:39