• This is the Main operation:

  

• XSLT transformation operation:

  

• Zip compression operation:

  

• getFileValue operation:

  

• The definition() operation in syllabi_import_form class:

  

My objective about this proposition is having a deeper knowledgement about Software Enginering and working methodology. In order to achieve that, I was preparing my PC to make nice class diagrams and sequence diagrams.

The "Free Software Market" about UML isn't too much good. I've tested some programs and very few ones completed my needs:

• ArgoUML: It lacks of a very intuitive interface and some basic functionalities that I find vital, and it doesn't allow me to do things in the way I want (bad class diagrams, bad sequence diagrams)
• Violet: It is not updated to UML2, so I couldn't do some stuff like fragments in sequence diagrams
• UMLet: It would be really good if it had a simple, but very necessary tool: a ZOOM!
• BoUML: You can't do constructors in sequence diagrams.

So, after some research, I found 2 programs which fit on my needs:

• SDedit: Probably the best sequence diagram editor I've ever seen. It is not a WYSIWYG editor like the others, you have to know some easy-to-use code (read the program's help) to make sequence diagrams. You type a simple code, and the diagram is drawn while you're doing that. Once you are used to it, the sequence diagram production speeds up in a considerable way, and the diagrams it makes are really nice.

  As it is not a WYSIWYG program, it introduces us to a new philosophy: Dragging&dropping, mouse moves... it's rather slower than simply typing some short lines with keyboard. I leant this concept and idea, and I find it well-builded in empirical demonstrations. I, for instance, I can make sequence diagrams fastly. With a "drawing" (WYSIWYG) editor I spend more time. I can assure you this.

• Dia: SDedit is a program that has sense: Sequence diagrams are just this, sequential. They can be builded and all drawn objects can have a fixed position in the diagram and it will be well shown; in class diagrams it's not possible to do that (or it is really harder), because you can position your items and classes in many ways and are all pretty or more understandable.

  I was looking for a program to design class diagrams as I design sequence diagrams in SDedit, by code; nevertheless, for the reasons explained above, I have not find any program such that (or I'm so stupid that I am not able to find it), so I had to give up and use a decent WYSIWYG editor. I found Dia for this, it's a great program, similar to Visio, it allows me to do very nice class diagrams in UML. It is far better than all described above, but by default it doesn't allow to create associative classes (it's not a huge problem but it could be good to have them), and last time I tried it, after forcing a bit the program capabilities, I recived a Segmentation Fault, loosing my time. It was not very happy, but I will give him a new try.

As a first requirement, I can make an abstraction:

1. First, I have to found, in the restoring process, where the new wiki ID is given and restored.
2. Then, after the piece of code I found before, I have to retrieve the new ID value.
3. Then, I have to locate the code where the link resources are restored.
4. Finally, I have to modify every link that will be restored in the previous founded code, retrieving the current link direction, and modifying the id parameter to the previous retrieved ID value from wiki.

I hope it won't be so hard to perform, however Marc's purposes for this piece of work are merely for my own learning and education.

Marc has explained to me that I will work on DFWiki code refactoring (lot of work is coming OMG), so as a training he demanded me to program a "foo" (example) Moodle format course, Moodle module and a Moodle block. This job has priority for me over the "ID" job explained previously.

In Moodle wiki I remember founding something related with that (some module/block/course format templates), so I'm going to take a look immediately.

Ok guys, let's work!

I never did any XSL transformation or programmed a XSL file, and I needed learning some advanced XSL features immediatelly not recommended for a newbie who wants to learn XSL as a hobby :). Also I had to adapt the xsl syntax to moodle, because Moodle needs "special" considerations:

1. Moodle xml files have very separated parts in the document. However, some parts have a very close relationship, and this relation can only be linked with an Identifier. But this identifier needs to be independent of the XML syllabi, so after some heavy research, the XSL function I needed for this was "generate-id" (this function generates a unique ID for a node, ideal for the lesson bucle).
2. I didn't know why Moodle, after the point 1 application, gave me errors didn't allow me to create a course. The explanation was that generate-id generates an id like "id7623472". Moodle only reads numbers, not strings!, so I have to discard the "id" string with "substring" xsl function.
3. In bucles, I needed incremental variables (aka i++ :)). Nevertheless, "variable" xsl element doesn't allow changing his first assigned value (OMG, problem!), because XSL is a declarative language, not a procedural one like C++ or PHP. The first and valid approach I found to solve this problem was the "number" xsl element. In a bucle, it makes something like a counter, from 1 to N being N the number of iterations. I found it a rustic and 'vaste' method, but valid for my purposes :)

After all these ones, and spending some time, finally I've finished the XSL file and it works perfectly. But this XSL file is built over a syllabi prototype, not over a final version, so I will have to modify it a lot when I recive it.

Now, I've finished all my work on OpenSyllabus integration prototype for Moodlemoot for now until "new external requirements" (probably they will arrive soon).

As you can see, in my blog entries I'm writing about XML files and other kind of resources, but I don't put any example to allow you understanding me clearly. Once I finish the project I will upload all those files and will modify all posts adding to them the mentioned ones (or until my teacher tells me that it could be good to upload them while they are in process).

1. I've no idea about PHP (I'm a pure Java developer, I've never touched PHP).
2. How can I add a new link (which points to the import form) in the Moodle admin block?
3. How can I create a form for allowing a user to upload a file compatible with Moodle?
4. How can I retrieve the file? And the name of the file?
5. How can I store a file into an specific folder in PHP?
6. How can I process a XML file with an XSL parser with my XSL file to transform it into another XML file in PHP?
7. How can I zip files in PHP?
8. How can I reuse the restore implementation?

Well, all these questions have their proper answer. But where can I find the answers and understand them? Afortunately I've already found them, however, it has not been easy:

• Or I'm stupid and I can't find it, or Moodle lacks of a good developer documentation (such as complete class diagrams, specifications, sequence diagrams, proper explanations...). It only has an API over hundreds of files composing Moodle (omg, finding something has been really hard).
• I'm tired of searching concrete functions among the API files. Is the Moodle API useful or useless? Can I do my job with brute programming? Or has someone implemented what I need yet?

After some days of desperate study:

1. PHP is an Object Oriented language, so a port from Java should not be too difficult. PHP is rather different than Java, however it has some similarities (like classes, attributes...), so with some practice, learning PHP should be easier (in fact, I believe I know now PHP and now I can program better than some time ago)

2. I've found the admin block is implemented in admin/settings. I've located my option link in courses.php file:

   $ADMIN->add('courses', new admin_externalpage('osylimp', get_string('osylimp', 'admin'), $CFG->wwwroot . '/course/osyl.php'));

3. Moodle has a superclass for forms, called moodleform (located at lib/formslib.php). Using a form example (edit_form.php located in course folder), I've created a new subclass, called syllabi_import_form.

   But the form example doesn't have a field for uploading files. How can I make one? After lot of websearching and coffees, I've found that I can add a line into the definition function of my new class:

   $mform->addElement('file','syllabi', 'XML course file','maxlength="150" size="20"');

   There were lots of similar lines in the document, however, replacing the first parameter with 'file' I've created a field for uploading files.

4. For retrieving the file value, exists a moodle function for forms: getElementValue. Passing as parameter the name of the file, it will retrieve the value entered by the user. Nevertheless, the value returned by getElementValue for the file field was an array. Arrays in PHP are rather different than Java:

   For expressing an array, in Java we use this expression: namevariable[integer]. In PHP, is something similar, but different. Arrays can be used in many ways, like hash tables, priority queues, stacks... so you can use also strings into the [], and mapping a key to a value in the array. See PHP documentation for further explanation.

   Finally, I could retrieve the name of the file :)

5. For retrieving the file and store it, Moodle forms have a method for storing into an specific path all files the user wants to upload: "save_files".

6. There are lots of XSL parser for PHP: the most interesting I found was Sablotron. However, I couldn't get it working, so I've used the built-in XSLT parser (libxslt library). In PHP documentation about XSL I've found some functions to get it working. This is the main procedure:

   $xp = new XSLTProcessor(); //First we create a XSLT process
$xsl = new DomDocument; //Then, we must load an XSL file
$xsl->load('../OsylCourse.xsl');

$xp->importStylesheet($xsl); //After that, we must import the XSL file
//to the XSLT process
$xml_doc = new DomDocument; //now we have to load the XML file
$xml_doc->load($CFG->dataroot.'/3/backupdata/'.$file['name']);
/*finally, we have to apply the transformation to the document and
save it to a file*/
if ($xml_out = $xp->transformToDOC($xml_doc)) {
$xml_out->save($CFG->dataroot.'/3/backupdata/moodle.xml');
} else {
trigger_error('XSL transformation failed.', E_USER_ERROR);
}

7. Zipping a file is quite easy:

   $zip = new ZipArchive(); //First we create an instance of a Zip file
/*Then, with open system call we create a zip file*/
if ($zip->open($CFG->dataroot.'/3/backupdata/course.zip', ZIPARCHIVE::CREATE)!==TRUE) {
exit("cannot open");
}
//Add as many files as you want (also directories)
$zip->addFile($CFG->dataroot.'/3/backupdata/moodle.xml', 'moodle.xml');
//Close the zip file
$zip->close();


   For further information see PHP Documentation for ZIP.

8. Reuse the restoration code is easy. Simply pass as a parameter the recently zipped file.

Well, that's all for now. However, there are plenty of bugs. For now, I'm only making a functional prototype for Moodlemoot... Doing things well requires time :)