X-Git-Url: http://git.rohieb.name/skm-ma-ws1314.git/blobdiff_plain/fa6284da96446dd4a438bfb72d0e51c367dd3647..6fe1c75e6dfe5485572e9047019a04d1e13114f5:/sec-chatty-things.tex?ds=sidebyside

diff --git a/sec-chatty-things.tex b/sec-chatty-things.tex
index 25b1426..6acde0c 100644
--- a/sec-chatty-things.tex
+++ b/sec-chatty-things.tex
@@ -1,17 +1,16 @@
-\section{System Architecture of ``Chatty Things''}
+\section{System Architecture of ``Chatty Things''}\label{sec:arch}
 
 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}
 \subsection{Service Provisioning Sublayer}
 
 Considering the application in deeply embedded systems and the special needs of
-the Internet of Things on the one hand, the protocol stack needs to fulfil
+the Internet of Things on the one hand, the protocol stack needs to fulfill
 certain technical requirements.
 
-First, memory, computing resources and bandwith on embedded systems are limited,
+First, memory, computing resources and bandwidth on embedded systems are limited,
 which demands for a lightweight protocol stack without too much overhead and
 predictable memory consumption, while also retaining enough flexibility for
 future development. The authors therefore provide only the most essential
@@ -32,14 +31,13 @@ Furthermore, Klauck and Kirsche implemented new features for uXMPP, which were
 realized as separate modules to allow enabling and disabling them at runtime,
 thus further reducing the memory footprint of a running system:
 
-\todo{minimize space between list items}
 \begin{itemize}
   \item support for IPv6
   \item support for Multi-User Chats (XEP-0045), which are used for information
     filtering
   \item support for SASL ANONYMOUS login for XMPP servers \cite{xep0175}
   \item a new publish-subscribe mechanism called Temporary Subscription for
-    Presence (see \ref{sec:tsp})
+    Presence (see Section~\ref{sec:tsp})
   \item XMPP Serverless Messaging (XEP-0174), using \term{uBonjour} as
     underlying mDNS/DNS-SD implementation for Contiki.
 \end{itemize}
@@ -48,8 +46,6 @@ The resulting implementation (uXMPP and uBonjour) gets by with 12{.}2\ kBytes of
 ROM and 0{.}63\ kBytes of RAM, which was about the size of the original,
 unoptimized uXMPP implementation while also implementing new features.
 
-\todo{figure of example network structure with and without central server}
-
 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
@@ -57,20 +53,20 @@ 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.
+server must exist and must be configured to supply this login method in order
+for this approach to work.
 
 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
 join the chat with a standard XMPP client on her machine and interact with all
-devices of a topic, or she can also interact with them directly.
+devices of a topic, or she can also interact with single devices directly.
 
 In scenarios without an XMPP server, the XEP-0174 module is activated and
 devices talk directly with the user or with other devices. This method has the
 drawback that Multi-User Chats cannot be used for topic filtering, since no
 method is specified to do XEP-0045 and XEP-0174 at the same time. In this case,
 a user must have an XEP-0174-compliant chat client, but it also gives her the
-opportunity to interact with things spontaneously on an ad-hoc basis (e.~g. when
+opportunity to interact with things spontaneously on an ad hoc basis (e.~g. when
 entering a room) without need for any additional gateway on the application
 level.
 
@@ -81,7 +77,7 @@ level.
 \subsection{Bootstrapping}
 
 With the given approach, bootstrapping new Chatty Things is easy and no
-configuration is neccessary: on the network layer, IP addresses can simply be
+configuration is necessary: on the network layer, IP addresses can simply be
 obtained using IPv4 Link-Local Addressing or IPv6 Stateless Address
 Autoconfiguration. On the transport layer, all needed ports can be obtained over
 DNS-Based Service Discovery. Finally, on the application layer, host names can
@@ -93,26 +89,26 @@ over XMPP Serverless Messaging.
 Bootstrapping a Chatty Thing therefore incorporates three steps:
 
 \begin{enumerate}
-  \item Activate uBonjour and try to discover an XMPP server
+  \item Activate uBonjour and try to discover an XMPP server.
   \item If a server is found, connect to it using ANONYMOUS login, join
     topic-based Multi-User Chats, deactivate the uBonjour client
-    \term(Infrastructure mode).
-  \item If no server is found, activate the XEP-0174 client \term{Ad-hoc mode}.
+    \term{(Infrastructure mode).}
+  \item If no server is found, activate the XEP-0174 client \term{(Ad hoc
+    mode)}.
 \end{enumerate}
 
-During runtime, a device can then react to changes in network infrastructure:
+During runtime, a device can then react to changes in network infrastructure by
+changing from one mode to the other:
 
 \begin{itemize}
   \item In Infrastructure mode: when connection to the server is lost, enable
     the uBonjour client, try to find a server, and when none is found, enable
     Serverless Messaging.
-  \item In Ad-hoc mode: if uBonjour detects a new XMPP server joining the
+  \item In Ad hoc mode: if uBonjour detects a new XMPP server joining the
     network, try to connect to it. If this succeeds, disable Serverless
     Messaging and uBonjour and join topic-based Multi-User Chats.
 \end{itemize}
 
-\todo{short conclusion?}
-
 \subsection{Temporary Subscription for Presence}\label{sec:tsp}
 
 To further reduce the message overhead and allow more fine-grained control over
@@ -125,8 +121,8 @@ 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.
+of subscriptions and unsubscription messages, 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
