\chapter{Summary and Future Work}

 \label{chp:summary}

 \section{Conclusion}

 \label{sec:conclusion}

 To fulfill the user requirements mentioned in section

 \ref{sec:hardest-isac-requiremnts} Ajax is clearly the way to go. At this time

 Ajax provides the technical solutions for propagating states from the web server

 to the web browser. Especially the DWR framework (see \cite{dwr}) provides a lot

 of ready-to-use components.

 In my opinion Ajax is also some kind of tricky technology. It is not easy to

 learn how to work with Ajax from one day to another. There should be some good

 background knowledge about how Ajax works. In section

 \ref{sec:preparatory-work} I suggest how to start working with Ajax and how to

 gain some good background knowledge. I cannot emphasize enough how important it

 is to understand the basics of Ajax. Otherwise one might end up searching 

 for errors all the time instead of being productive.

 \section{Directory Structure of \isac s Web Application}

 \label{sec:dir-structure-web-app}

 During my work within the \sisac team I proposed the following directory

 structure for developing the \sisac web application. This directory

 structure satisfies both, the Servlet specification and the directory structure

 needed by Eclipse.

 A typical web application during development consists of different directories

 which serve their own purpose. In this section I will explain which resources

 belong into which directory.

 The basic layout of \sisac's web application looks like this:

 \begin{verbatim}

  1    isacweb

  2      |-src 

  3      |-doc 

  4      |-isac 

  5      |  |-css 

  6      |  |-images 

  7      |  |-js 

  8      |  |-WEB-INF 

  9      |  |    |-lib 

 10      |  |    |-classes 

 11      |  |    |-web.xml 

 12      |  |-index.jsp 

 13      |-work

 \end{verbatim}

 The \texttt{src} directory in line 2 in the above listing 

 contains all sources of the web application. Such sources are Java files,

 Property files or XML files. When the project gets compiled, all sources are

 copied to the \texttt{WEB-INF/classes} directory (line 10). Java files get

 compiled and the their corresponding class files are copied to the

 \texttt{WEB-INF/classes} directory. All non Java files are copied one-to-one

 into the \texttt{WEB-INF/classes} directory.

 The \texttt{doc} directory (line 3) contains useful documentation for both, the

 end user and developer of the web application.

 The web application itself starts at the directory \texttt{isac} (line 4). As

 stated in

 the Servlet specification (see \cite{jsr154}) a web application consists of a

 \texttt{WEB-INF} directory (line 8) and inside this directory there are the

 \texttt{classes} and \texttt{lib} directory (line 9 and 10). As mentioned

 above, the \texttt{classes} directory is the target directory for compilation.

 The \texttt{lib} directory contains all 3rd party JARs needed for the web

 application.

 As you can guess, cascading stylesheet files go into the \texttt{css}

 directory (line 5), Javascript files belong into the \texttt{js} directory (line

 7) and images should be put into the \texttt{images} directory (line 6).

 The JavaServer Pages itself (JSP files) reside in the root of the web

 application, which is the \texttt{isac} directory (line 4) in this case.

 The \texttt{work} directory is a temporary directory for tomcat and contains no

 resources from developers. Tomcat compiles the JSP files into Servlets and

 stores them in the work directory.

 \section{Preparatory work}

 \label{sec:preparatory-work}

 Ajax is a very new technology and new frameworks for Ajax pop out from

 everywhere. During my work with the \sisac team I evaluated some Ajax

 frameworks. The DWR framework (see \cite{dwr}) is a very powerful framework and

 very convenient to use. There are a lot of examples which show how to use the

 different methods of getting data from the server. It is even possible to access

 Java classes from Javascript code within the web page. Another very powerful

 feature is that the server can send events to the client, which is not obvious a

 the first glance of a web application.

 \subsection{Tomcat and Servlets}

 \label{subsec:tomcat-servlets}

 A good point to start is to get familiar with Apache

 Tomcat\footnote{\url{http://tomcat.apache.org}} and the Servlet technology

 \footnote{\url{http://java.sun.com/products/servlet/}}. Since \sisac will use

 Apache Tomcat in version 6, the right specifications to look at are Servlet

 specification 2.5 and JSP specification 2.1.

 I suggest to try some examples with Tomcat, to write a Servlet and a JSP file

 to become familiar with Servlets and JSPs. If you work with Ajax, you do not

 deal directly with Servlets and JSPs, but when searching for bugs and errors a

 little background knowledge is recommended.

 \subsection{Ajax}

 \label{subsec:ajax}

 To start with Ajax, I recommend the book Head Rush Ajax \cite{head-rush-ajax}.

 It starts with the very basics of Ajax and winds up with some advanced

 concepts, i.g. using JSON \footnote{\url{http://www.json.org/js.html}} to send

 an receive data.

 Writing your own code to create a \texttt{XMLHttpRequest} and sending some data

 to the server, perhaps to a servlet, is also recommended. So you get a feeling

 of what is going on behind the scene. Jumping directly into the DWR framework

 with no knowledge about Ajax and Servlets may be very cumbersome, especially

 when you are looking for errors.

 \subsection{Firebug}

 \label{subsec:firebug}

 Another useful tool for debugging Javascript is Firebug

 \footnote{\url{https://addons.mozilla.org/de/firefox/addon/1843}}. Firebug is an

 add-on to the Mozilla Firefox web browser. It shows you if you have errors in

 your Javascript code on your web page. It is also possible to debug within the

 Javascript code. I highly recommend using this tool because it makes it very

 easy to find errors if you are working with Javascript.