project proposal

The scaffold for this proposal is taken from from the UOS website.

Purpose (problem statement):
To simplify the process whereby student's find clubs and societies that they are interested in. That is creating an new channel of communication between students and clubs and societies of the university.

Background:
Currently the only techniques in place to join students with the clubs and societies they are interested with is during O - Week in the week 0 of semester 1(and to a lesser extent Re - O Week week 1 of semester 2). Also there is a directory of all clubs that are registered on the Union website. Now the problem with this is that is hard to navigate, and is unsearchable. This web site does not provide a mechanism to formulate links between the students and the clubs.
By providing a new way to find the clubs and socs that students like it will help keep memberships in the clubs growing and allow more student's to have the complete university experience. The Clubs and Socs program provides an important part of the university experience.

Users / Actors:
The actors that will use the application are as follows:
1) Clubs and Socs Executive: It is their role to update and upload information about their particular club.
2) Clubs and Socs Administrators: These are the union execs that run clubs and socs, it's their job to add club and socs execs as part of the registration every year.
3) Students: who can search the system and get in contact with the clubs and socs they want.

Use Cases:
1. Add / Edit / Remove Club and Soc Exec
2. Add Club Information
3. Search for a Club
4. Contact a club (this one may change submit interest)

These use cases may evolve over time.

recent labs + hibernate

Monday's lab for me well was out... epilepsy and all ... well i'll try to get the hibernate part done asap, also this weekend i will finish readings and write the description for the project.

extra lab

So I went into the lab today and did some work, i finished of the Ant JUnit part. Also i did the form data. The form part was quite easy however it was something that i had not used. Everything was integrated with Spring. The main issue that was quite new was the integrated with tags. The tagging library allowed the inbuilt Spring framework to be used at all areas of Web IO. The reason this is powerful is that we can then use the internal Spring functions to do things like:

• Validation
• DB connections
• Log in etc.

I think this is much better than using simple standard xHTML tags. We can then form better automation and the system will be scalable.

Other things that I needed to mention that were important are:

• Tagging is a critical part of Spring and i need to look at this a bit more.
  
• JSP relies heavily xml and the web xml files. The strucutre of these needs to be learnt instead of relying too heavily on the files that are already there

lab 2

Lab 2 was not as productive since i ran into major issues with the JUnit part. This was because of a faculty install, and so i was the Guinea Pig for the solution. At the end of the day it did work and the JUnit tests (which i knew how to do) worked.
One thing i did learn though was the way to make ant do them for you (even though this took forever to get working) This can be useful in the long run. I will be going back to the lab on Wednesday to finish of section 3 and 4. This should be more productive as i will begin using things like tag libraries and forms, which i am new to.

Croosing chasms

Crossing Chasms: a pattern language for OO application frameworks.
Brown, K. and Whitenack, B.
Vlissides, J et al (eds), Pattern Languages of program design.

This paper deals with many issues with relation mappings to OO systems. This is a major issue in current real time OO centric systems. The paper concentrates on static mappings, that is how the objects map to tables and vice versa.
many of the issues raised come from basic DB theory and going from first Backus Normal form etc. Allot of the paper deals with the best way to deal with relationships and map these things from a design standpoint. Allot of this is hidden is we use something like Hibernate.
However we will return to this paper after we do some more things on Hibernate. However some key points to note:

• Look at the way objects map to the DB early so this mapping has some significant effect.
• Ensure you spend time with the database and map the relationships like you would when you going from 1st order through to 4th order BN.
• You will need to give every object some unique key, in order to make the relational world happy, that is everything will need some form of primary key, and this will help to amp relationships (from simple 1 : 1 to inheritance mappings).
• You will need to have some idea about the way the database stores primitive types so you know what format things will map to.
• When dealing with the issues of relationships you should use direct access (i.e. pointers within the object) rather than relying on the presence of foreign keys which is inherently slow. However ensure that these do exist and are updated to ensure that when an object needs to be instantiated it can be.

Frameworks = components + patterns

Johnson, Ralph E
Communications of the ACM. Vol 40, (10) pp. 39 - 42

In order to understand frameworks you must first try and define them. We can define a framework in a computer sense as a reusable design of parts of a system represented by abstract classes. It provides a customizable interface for developers to use.
Frameworks are like components (such as those components in an OLE library) however they are more complex and also you can customise them allot further. A component can be thought as simply code reuse. A framework is more than that, it is actually design use as well.
Frameworks reuse design aspects like a template or a high level schema. The difference is that a framework has been described in a fixed programming language (Java or C++).
Reusing design has its benefits and its own cots. In the long run you can save time and money with Frameworks, however there is always the steep learning curve associated with developing it.
A pattern is a way to describe a solution to a problem in a certain context. Frameworks implement patterns in a specific way. That is they transform context specific ideas into some tangible code that solves a certain problem. For instance MVC is really a pattern, however the way Spring implements MVC can be though more as a framework.
Frameworks are in the middle between pure code reuse or design reuse. The allow us to use design principles and patterns in a language (and hence domain) specific way.

lab 1

Today's lab had many different parts to it these included:

• Eclipse
• Tomcat
• Spring
• Ant
• J2EE and JSP
• Linux
• Servlet
• JSTL
  

The first part of the lab was easy for me as i have experience with Ant and Eclipse on Linux. However below are some thoughts and things that i should note for later.

Ant provides a tool to deploy, compile and clean the Java app. It serves the same purpose as make with added features. The main part of the Ant program that we deal with is the build.xml file and the build.properties file. These file together provide the deploy, build and clean commands. the properties file gives project specific components such as: location of files. One thing that i noticed is the layout that they want us to use. That is the file layout is different to the one that we would see in normal J2EE apps that i have dealt with before. This is the way that Spring likes it and so we will try to follow it.

The general structure is:
\
|-src
--|bus
--|web
|-war
--|-WEB-INF
----|-jsp
----|-classes
----|-lib
build.xml
build.properties

This is what we will try and keep with.

The next part that was also quite quick was Tomcat. The tomcat file is located in the /opt/tomcat/ folder and is copied to /tmp/tomcat/ at each start up. Tomcat is used in order to deploy our Java app. It does this by using servlets.

The next part was new for me as i have no experience with Spring. Spring is a framework that provides a vast amount of functionality. We use it mainly for the MVC components that it offers. Spring uses servlets in order to perform tasks. So there is a Dispatcher servlet, and a mapping servlet (both which are in our web.xml file)
Once we have this we can form the beans which define the instances of the mapping servlet and dispatcher servlet. This goes into our app specific .xml file. In order to make all this work we require a large amount of extra data in the form of all the libraries. These are copied to our WEB-INF/lib directory and are in the form of JARs.
Spring uses as default the Logger4J app, and so this also is included and written to.

The main issue that we have at this stage is that the model and the view are as one. IN a real MVC app we want the Model and View decoupled. To do this we use a class provided by the Spring framework (InternalResourceViewResolver) . This is instantiated by the use of beans. Doing this decouples the View and Model. and combines them only after the particular view has been resolved.

The business logic is added using simple classes e.g. we use products in order to perform our tasks, these all go into the src file and are split in terms of business logic and web (the controller itself). The controller is an important part as what it does is combine the view and the model, and includes any business logic that is required.
In order to have some data we again use beans to populate our data. This is done in the xml file that controls the app servlet. This is important as it is the app specific things that want to populate this app with certain beans.

The final part of the lab was improving our ant instance with more functionality (again this is easy).

Reflections on what i learnt:

Today i completed Part 1 and Part 2 of the labs. The main concepts and skills i learn was:

• Use of Spring: how spring works and what you need to do to make it help you
• The organisation of Spring and what is offers. That is the MVC and the many classes files.
• Logger 4J interface.
• Beans as applied to Spring, and MVC.
• Using Spring to build an app.

The next thing i need to do is make my own app and try not use the files they have given rather then modifying files try and write the sevlets myself. Also try and write some beans.