PHP HTTP Authentication

The HTTP Authentication for PHP comes in two versions, “Basic” and “Digest”.

• Basic sends the username and password across the net in plain text.
• Digest uses some clever one-way encryption techniques (eg. MD5 or SHA1) to prove that both client and server are exactly who they say they are without actually sending the password at all (in fact the server doesn't even need to store the password itself).

A problem with HTTP Authentication is that there is no way to easily logout, in fact there is no support for logging out. The browser can access the restricted material until such time that the cached credentials are flushed. This usually happens when the browser is closed.

Beginning PHP and MySQL 5 - Chapters 1-7

Ch 1 - An Introduction to PHP
Basically the history of PHP and why you should use it.

Ch 2 - Installing and Configuring Apache and PHP
Useful in getting started up. There are a lot of configuration options listed out. Using default values so skipped over it for now.

Ch 3 - PHP Basics
Learned the syntax that are available, quite a few including a short form version. Went through comments, outputting to html, datatypes, variables and constants, expessions and control structures like if, if-else and switch.

Ch 4 - Functions
All about functions, the prototype for a function is similar to a method:

function function_name(parameters)
{
   function-body
}

There is no return type required. If needed, it can be added to the body.

Variable functions are functions which are evaluated at execution time to retrieve their names:

$function()

Given a URL parameter, this allows one to bypass the tedious if statement in order to know which function to call:

if($trigger == "retrieveUser")
{
   retrieveUser($rowid);
}
else if($trigger == "retrieveNews")
{
   retrieveNews($rowid);
}
else if($trigger == "retrieveWeather")
{
   retrieveWeather($rowid);
}

to the much more compact:

$trigger($rowid);

There are security risks in using this so care must be taken.

Reuseable functions can be stored in a function library and called up by:

include("function.library.php");

Ch 5 - Arrays
Of note is the natural sorting function, natsort(), which sorts (10, 1, 20, 2) to (1, 2, 10, 20) instead of (1, 10, 2, 20).

Ch 6 - Object-Oriented PHP
Normal OO stuff that can be found in C or Java. The Properties feature in PHP can be used to extend the class by adding in new properties. A potential gotcha for constructors is that they do not call the parent constructor automatically.

Ch 7 - Advanced OOP Features
Again more of the same. However there are OOP features that are not supported such constructor, method and operator overloading. There is a section on reflection, showing how to obtain the class type, methods and parameters.

Initial thoughts on PHP

Learning PHP through a book entitled Beginning PHP and MySQL 5: From Novice to Professional, Second Edition by W. Jason Gilmore.

PHP is a loosely-typed language due to its origin as a web counter script. This is inherent in the quick and dirty way it does things, one can put in a variable and assign and reassign it to various data types like strings, integers and floats. There is no need for declarations and type-casting, though it is available. Coming from a Java background, that is very off-putting. Acclimation would be easy but care must be taken to prevent any bad programming habits from creeping in.

The OOP aspect of PHP is a mix of C and Java coding styles. In that respect, it is pretty conventional and a Java programmer can take easily to it. Relatively simple websites should be easy to prototype quickly.

Installing CruiseControl - a continuous integration framework

The first step in installing CruiseControl (CC) is going to the SourceForge site and downloading the distribution. There are two flavors, a binary and a source distribution. You should choose the binary distribution as it is a trimmed version of the source distribution and is much simpler to use. After the download, extract the file to where you want to place it.

From here, you will want to follow the getting started guides for the binary and source distributions in order to set up CruiseControl. The binary distribution lets you run it 'out of the box' and you can see how a functional CC is supposed to work. Once you have the hang of it, you can try out putting your own project under CC. Using the guide for the source distribution, under the "Running the Build Loop" section, you can specify a place to store all your work.

Now the binary distribution sets the root of the CC directory to where the sh/bat executive file is called from. The requirement is that CC's lib and dist directories must be there. So the default is to call cruisecontrol.sh from the extraction place, that will also bind the project storage to be there. If you call the sh file from the specified place in the previous paragraph, CC will complain about not finding the lib and dist directories. The solution is to edit cruisecontrol.sh and hardcode the CCDIR to the extraction place, then call it from the project storage. Note that the binary distribution uses a projects directory instead of a checkout directory.

After that, follow the guide in creating config.xml and build-.xml, making changes as necessary. CC makes use of the Ant build tool so all the project compiling, testing and archiving are done using that. This site tells you how to make use of SVN in Ant instead of CVS.

Links:

• CruiseControl
• Getting Started with the Binary Distribution
• Getting Started with the Source Distribution
• JDeveloper, Subversion and Cruise Control

Continuous Integration

Continuous Integration (CI) is a software development practice of having team members integrate their work into the project frequently. Every integration is automatically built and tested so integration errors can be flushed out.

From Martin Fowler's article on CI, the practices to follow are:

1. Maintain a Single Source Repository
2. Automate the Build
3. Make Your Build Self-Testing
4. Everyone Commits Every Day
5. Every Commit Should Build the Mainline on an Integration Machine
6. Keep the Build Fast
7. Test in a Clone of the Production Environment
8. Make it Easy for Anyone to Get the Latest Executable
9. Everyone can see what's happening
10. Automate Deployment

Current practice at the moment only make use of steps 1 and 2. With step 2, though an Ant build script is present, the Eclipse IDE's automatic build is favored.

Step 3 - Tests are coded but currently they are run by hand, not in conjunction with the build. Step 4 - This is not adhered to, usually committing is done when a large task has been completed.

Steps 5, 6 and 7 are not relevant with the current practice.

Step 8 - Current practice is to ask developer for the latest code, use the source repository to transfer the code then build it. If the code is transferred to a new machine, custom settings have to be supplied before it can be built. Generally a lot of hassle and potential pitfalls.

Step 9 - Only the developer knows what's happening, anyone else has to be informed by that person.

Step 10 - The Ant build script has a deployment task. However that task only deals with production deployment which is set to a particular server and is not suitable for testing.

CI is supposed to lessen integration impact and allow for better communication between team members who are working on a project. Being a development team of one, there are no major issues. Anything that occurs is the result of that single developer and must subsequently be resolved by that person. However that will change as the team grows.

Wicket (vs. Tapestry)

Wicket, as with Tapestry, is a view technology that uses plain HTML and Java code to render web sites. However where with Tapestry you have the controlling logic split between the Java code and html/page files, Wicket thrusts all logic into the Java code and use the html pages only to define the position of its components.

In addition, there is no xml configuration needed aside from the inclusion of the Wicket servlet into the web application. Any configuration is done in Java code. As such the components in Wicket can be reused and also inherit from other components, normal Java behaviour.

After trying Wicket for a few days, it is very much easier to use than Tapestry. The split logic in Tapestry forces one to constantly refer to the html pages for what components are used and their settings and the Java for the logic behaviour. Keeping all the logic in Java enables one to have a clearer picture on what the components are and what they do, and the html pages only need their wicket ids to function.

Another thing is the strict enforcement of wicket ids referencing their respective components. If one has a wicket id that is not referencing a component somewhere in the Java code, the webapp cannot render it and gives an error page. Similarly for a component that tries to add itself to a page without an id.

Shifting from Tapestry, one had to change their coding mindset from a single Java file for a html page. Wicket also requires that, however a base page can be defined and, taking advantage of inheritance, be extended by other pages. Components in one page can be reused in another and so on.

Maven

http://maven.apache.org/

Maven can be run straight out of the archive, once the systempath variables are set. Following the 5 minutes guide, I created a 'Hello World' app, compiled, tested and finally packaged it into a jar. Going further, using 'mvn eclipse:eclipse' allowed it to be imported into the Eclipse IDE. There is also a plugin available for tight integration between Maven and Eclipse.

Dependency management is one prime reason for using Maven. The dependencies are downloaded from a remote repository and stored in a local repository that Maven creates. So for several projects, there will be only be one dependency copy. The default remote repository can be changed to an internal repository that will house a private copy of dependencies.

In regards to Ant, Maven makes for a more standardized build process, with little or no configuration needed to start creating, building and testing projects. It provides a common directory layout for each Maven project, easing orientation.