Extensibility API
Using the extension mechanism, you can add / modify / delete iTop objects, and change the application (menus, user rights, …)
But iTop is also providing some means to alter the application behavior using PHP.
Object manipulation API
When adding new behaviors, you'll surely have to :
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Retrieve objects from database
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Get attributes of a retrieved object
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Modify an object in memory
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Store the modification to database
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…
In the following document you'll learn how to do that in PHP : API for searching objects, manipulating them,....
Business logic on objects
Since iTop 3.1.0, the preferred way to add business logic on objects creation / modification / deletion is to use the new event system. But before this version we had two API. Here is a comparison between the 3 API :
| API | Support | Pros & Cons |
|---|---|---|
| CRUD events | Since iTop 3.1, though still experimental ⚗️ | ➕ Has been designed having in mind the caveats of
the two original methods ➕ Multiple events available ➕ Multiple extensions can listen for the same event, and order can be defined ➕ Listeners can be part of the object definition ➕ XML extensibility mechanism ( _delta attribute)➕ Any extension can add its own events ➖ Cannot override parent listener method |
DBObject methods override |
Since iTop 1.0 | ➕ Can be included in the object definition (good
for processing needed for object integrity) ➕ XML extensibility mechanism ( _delta attribute)➖ Can only customize iTop objects CRUD operations ➖ Only one method override possible ➖ Requires a precise understanding of the CRUD stack (method to implement, getting previous values, objects reload, …) |
| iApplicationObjectExtension | Since iTop 1.0, aimed at being deprecated at some point in time | ➕ Multiple implementation possible ➕ Many behaviors can be customized (iTop objects CRUD operations, menus, web page content, …) ➖ No rank ➖ CRUD : just a few callbacks possible |
Events
All the details on this extensibility API: Events API - Adding new events, firing them, while others are listening and reacting on event occurrence.
When available for what you want to do, it is the recommended one
iTop interfaces API
In practice, your code consists in declaring a PHP class implementing an interface known by iTop as being an extension interface. iTop detects automatically the existence of your class and invokes the methods at some specific moments during its execution.
To make this happen, the code of your class must be in a file included by iTop, so included either in:
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main.my-module.phpfile (see Content of a module and the step by step tutorial on creating a module) -
snippet XML node (see XML Data Model Reference)
To learn more about the available interfaces : Interfaces API
DBObject methods override
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Multiple DBObject methods are meant to be overridden to implement custom behaviors : if so they contains the
overwritable-hooktag in their phpdoc block. -
Some can be used to implement custom behaviors in the CRUD stack (Create, Update, Delete) for new iTop objects, also events are preferred in that case.
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To see when those methods are called, check the crud stack map
as two extension modules can become concurrent, one module erasing another module customization, just because it was loaded last at Setup.
That's why Events API or Interfaces API are preferable when there is a risk of concurrence