X-Git-Url: http://git.rohieb.name/skm-ma-ws1314.git/blobdiff_plain/018432fe79ed92035c902aba53c6595a2a417cc9..fa6284da96446dd4a438bfb72d0e51c367dd3647:/sec-chatty-things.tex

diff --git a/sec-chatty-things.tex b/sec-chatty-things.tex
index 01f0ed0..25b1426 100644
--- a/sec-chatty-things.tex
+++ b/sec-chatty-things.tex
@@ -1,7 +1,7 @@
 \section{System Architecture of ``Chatty Things''}
 
-After the underlying techniques have been explained, we can have a look at the
-system architecture which Klauck and
+After the underlying techniques have been explained, we can now have a look at
+the system architecture which Klauck and
 Kirsche~\cite{Klauck:2012:BCC:2352852.2352881} use to build Chatty Things.
 
 \pages{3}
@@ -53,11 +53,12 @@ unoptimized uXMPP implementation while also implementing new features.
 In order to react to different network infrastructures, their implementation
 allows both communication with a central XMPP server as well as peer-to-peer
 communication over XMPP Serverless Messaging. When a central XMPP server is
-detected over uBonjour, it is used instead with the ANONYMOUS login method, and the
-XEP-0174 module is disabled. The ANONYMOUS login method is chosen since TLS
-encryption is not yet implemented, and it assigns random JID to the client,
-which do not need to exist on the server. However, a server must exist and must
-be configured in order to use this method.
+detected over uBonjour, it is used instead with the ANONYMOUS login method, and
+the XEP-0174 module is disabled. The ANONYMOUS login method is chosen since TLS
+encryption is not yet implemented, and with this method, the server assigns a
+random JID to the client, which does not need to exist on the server. However, a
+server must exist and must be configured to use this login method in order to
+use this method.
 
 With a server, information filtering is achieved by creating topic-based
 Multi-User Chats where multiple devices can be grouped. A user can then simply
@@ -79,11 +80,6 @@ level.
 
 \subsection{Bootstrapping}
 
-In a distributed context like the Internet of Things, devices need to be ready
-to use out of the box. Users often do not want to set up configurations for each
-device they use, and when using several of those devices, it is often not
-reasonable having to configure every single one.
-
 With the given approach, bootstrapping new Chatty Things is easy and no
 configuration is neccessary: on the network layer, IP addresses can simply be
 obtained using IPv4 Link-Local Addressing or IPv6 Stateless Address
@@ -119,16 +115,18 @@ 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 and allow more fine-grained controls over
+To further reduce the message overhead and allow more fine-grained control 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.
+This technique builds on top of presence stanzas as defined in core XMPP, which
+are sent by default without a \code{to} or \code{from} attribute, and therefore
+fit into a single TCP/IP packet over IEEE~802.15.4. However, a drawback of the
+presence mechanism defined by core XMPP is the fact that a client must manually
+subscribe to presence information of another client in order to receive it,
+which requires further communication between the clients. Since the network can
+change rapidly, and clients can frequently join and leave the network,
+subscriptions would often be outdated and must be renewed, leading to 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