From: Roland Hieber Date: Sat, 14 Dec 2013 06:37:15 +0000 (+0100) Subject: sync: Temporary Subscription for Presence X-Git-Tag: erste-version~2 X-Git-Url: https://git.rohieb.name/skm-ma-ws1314.git/commitdiff_plain/ce4c9f88cbf50fc383af61d1131f706b0f1e5446 sync: Temporary Subscription for Presence --- diff --git a/sec-chatty-things.tex b/sec-chatty-things.tex index 01f0bb2..d748494 100644 --- a/sec-chatty-things.tex +++ b/sec-chatty-things.tex @@ -4,7 +4,6 @@ After the underlying techniques have been explained, we can have a look at the system architecture which Klauck and Kirsche~\cite{Klauck:2012:BCC:2352852.2352881} use to build Chatty Things. - \todo \pages{3} \subsection{Service Provisioning Sublayer} @@ -122,6 +121,23 @@ During runtime, a device can then react to changes in network infrastructure: \subsection{Temporary Subscription for Presence}\label{sec:tsp} -To further reduce the message overhead +To further reduce the message overhead and allow more fine-grained controls over +information filtering, \term{Temporary Subscription for Presence} is introduced. +This technique builds on top of presence stanzas as defined in core XMPP. These +presence stanzas are sent without a \code{to} or \code{from} attribute, and +therefore fit into a single TCP/IP packet over IEEE~802.15.4. However, to be +able to receive these stanzas, a client must manually subscribe to those +information in their roster, which requires further communication between nodes. As the network +can change rapidly, subscriptions would be often outdated, and there would be +much overhead of subscriptions and unsubscription packets, which would inhibit +the flow of the actual information. + +To solve this problem, a dynamic, topic-based roster is implemented on top of +Multi-User Chats (XEP-0045). Every topic corresponds with a chat room, and nodes +join the chat rooms which they are interested in. This allows nodes to inform +only interested nodes about updates. This has the advantage that existing +clients supporting Multi-User Chats can be used by a user, but Chatty Things and +XMPP servers need to be adapted to the new subscription model. Also, this +mechanism does not work with Serverless Messaging. % vim: set ft=tex et ts=2 sw=2 :