going to do
\section{Prerequisites}
-overview to the techniques used in the paper by Klauk and Kirsche
+overview to the techniques used in the paper by Klauck and Kirsche
\cite{klauck-kirsche-chattythings}
\subsection{Address allocation}
addresses in accordance with each other, so no IP address is used twice.
In respect to the Internet of Things, this decentralized approach has the
-advantage that devices can easily be used in different desployments, even where
+advantage that devices can easily be used in different deployments, even where
central infrastructures do not exist, and it also allows them to change their
addresses dynamically in order to react to changes in the network.
\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 bandwidth on embedded systems are limited,
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.
\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
\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
+ \item If no server is found, activate the XEP-0174 client \term{(Ad hoc
mode)}.
\end{enumerate}
\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}
\subsection{Future Work}
In addition to the XEPs covered above, there are a few additional XEPs which can
-be implemented to further increase the effictivity of Chatty Things. Especially
+be implemented to further increase the effectivity of Chatty Things. Especially
the documents XEP-0323 through XEP-0326 (which are currently in Experimental
status) are targeted to the Internet of Things.
\hline
Feature & Chatty Things & CoAP & MQTT & WS4D \\
\hline\hline
- application gateways neccessary & - & yes & yes & - \\ \hline
+ application gateways necessary & - & yes & yes & - \\ \hline
usable with standard clients & yes & - & - & (yes) \\ \hline
discovery support & yes & yes & - & yes\\ \hline
IPv6/6LoWPAN ready & yes & yes & ? & partial \\ \hline
Resources Working Group\footnote{\url{http://datatracker.ietf.org/wg/core/}},
but still has been only in draft status since 2010.\ It allows a mapping to
HTTP, and is therefore stateless, but it specifies a binary protocol, which
-makes it neccessary to deploy application-level gateways and special client
+makes it necessary to deploy application-level gateways and special client
software to communicate with its environment. It relies on UDP, but emulates
congestion control, message confirmation and message IDs, since – in contrast to
HTTP – messages can be sent asynchronously. Discovery is also specified and done
protocol, there is the need to implement at least an XML parser on each node,
which comes with protocol overhead and increased code size. However Klauck and
Kirsche show that with good optimization (in the code as well as in the
-procotol), a complete stack can be implemented in 12 kByte of ROM, which leaves
+protocol), a complete stack can be implemented in 12 kBytes of ROM, which leaves
enough space for other applications to be built onto it. As compared to Web
Services, Chatty Things are probably not as flexible, but they have less
overhead, even when using XML, while MQTT and CoAP provide less flexibility for
\begin{itemize}
\item an A record \code{capulet.local}, specifying her IP address,
\item an SRV record \code{juliet@capulet.\_presence.\_tcp.local}, specifying
- the port on which her XMPP client listens, and refering to
+ the port on which her XMPP client listens, and referring to
\code{capulet.local} as the host name
\item a PTR record \code{\_presence.\_tcp.local} for service discovery,
pointing to \code{juliet@capulet.\_presence.\_tcp.local}
projects / skm-ma-ws1314.git / commitdiff