Recently we started a proyect where we need to implement a webpage that should be able to manage google maps markers and locations, with aditional info on them. However the requirement was to do it as a Drupal module in order for the client to embed it on his existing web page powered by Drupal.
I have a strong background developing web pages using java technologies like JSF, and I have had some previous experience using PHP MVC frameworks like cake php, but that's the reason why I think I'm so confused with the module development process used in Drupal (hook methods and conventions...).
First of all I have been looking at the Drupal 7 module development book by Packt, and I just finished the chapter 4 where you're supposed to implement and theme a single blog module. However by using the techniques showed until that point... I find it extremely difficult to implement a google maps powered (Block???) by just theming it as lists or using the render API.
What I found really interesting was the possibility to use theme templates and create the block content based on them; by just passing variables and priting php statemnets..., but it's not explained very well on the book either. So that's why I wanted to ask you where I could find more resources about theme templates, so that I could just put my html markup and js functions on that template, and pass to it the processed variables.
Anyway I think my best bet would be to extend existing module funcionality. In example for the maps I would use the OpenLayers Drupal module that's already done and tested. However, I need to execute my own code logic when a marker is selected, so that's another question..., how Could I insert a callback or intercept the OpenLayers module's functions so that I can extend them and save the data on my own tables or any operation I needed.
Should I rewrite the module files to add more functionality?? or could I implement my own modules and just intercept method calls?.
I'm just starting Drupal, and I think is really simple... but just for showing content, on the other hand interacting with the user, retrieving data from clients, seems to be really really difficult, because I have no idea how to show custom html markup, or add js functions, and then executing php ajax function callbacks on the server. For all these reasons I'm felling a little bit overwhelmed, and I really really need some guidance, tutorials, resources to focus on..
Thanks a lot.