Introduce Event Manager for Efficient Event Handling and Routing

1 Initial Problem

To implement a workflow concept, all relevant processes should raise an event (much more than now), so that the workflow engine can be aware and react on them. The existing mechanism where a package describes in an xml file, which events it wants to listen to provides the possibility to filter the events. But that is very static and only changes on an update of this package.
Another possibility to listen to events is an event handling plugin, that can listen on an event. For a workflow environment this plugin must listen on all events and relay these events to the relevant processes/scripts, that should be executed. Most processes only react to one of these events. With a growing number of events, much unneeded traffic is generated, that slows the system down.

2 Conceptual Summary

We use an event handling plugin, that handles all events. Every process/script, that should be executed must be registered to a specific event.Furthermore the events can be filtered by the values, that are transmitted with theseevents.

So much less events are sent to processes, which reduces the overhead.
In the current implementation, the plugin does only make a simple comparison of event parameters with defined values for concrete processes. 
Another possibilty, that is not yet realised, would be a validate function in the process class that could be used, to determine quickly, if the process will handle that event. This validation function could handle more complex filtering  relations than the current simple comparison.

This functionality could be a useful enhancement of the ilias core, so that much more events could be filtered efficiently, to reduce the overhead, when more events are raised, as would be useful in a workflow engine environment.

3 User Interface Modifications

3.1 List of Affected Views

• A new administration entry under which the events and the executed processes can be be configured.
  

3.2 User Interface Details

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3.3 New User Interface Concepts

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3.4 Accessibility Implications

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4 Technical Information

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5 Privacy

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6 Security

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7 Contact

• Author of the Request: [vimotion] (Harald Grübele)
• Maintainer: {Please add your name before applying for an initial workshop or a Jour Fixe meeting.}
• Implementation of the feature is done by: {The maintainer must add the name of the implementing developer.}

8 Funding

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9 Discussion

10 Implementation

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Test Cases

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Approval

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