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Yet Another Event System - Revisited

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As a followup of my previous post Yet Another Event System?, it is time for a follow up on the code and examples.

The code has been added to Google Code and it's available for free at YAES source code. You can simply download the entire solution and start coding. If you're only interested in the main functionality class, go directly to ConfigurationManager.cs.

Installation

This is a normal Event System installation process:
  • Copy the compiled Event System DLL to a location of your choosing
  • Reference the DLL from file [Tridion_Home]\conf\Tridion.ContentManager.config, in section configuration / extensions / add, attribute assemblyFileName
  • Copy a .config file to the same directory where your Event System DLL is located, and name it the same as your DLL, but with extension .config
  • Restart Tridion processes. For knowing exactly which process to restart, have a look at my earlier post Debugging a Tridion 2011 Event System

Configuration

The .config file along with the DLL contains a few configuration options:

<configuration>
  <appSettings>
    <!-- Amount of minutes to keep a loaded Configuration dictionary in the cache -->
    <add key="SystemComponentCacheMinutes" value="5"/>

    <!-- Where to read the System Component from (Publication, Current, TcmUri or WebDavUrl). Multiple values are comma separated -->
    <add key="SystemComponentLocation" value="Publication"/>

    <!-- Which metadata field contains a Component Link to the SystemComponent. Multiple fields separated by commas -->
    <add key="SystemComponentField" value="Configuration,conf"/>

    <!-- Search for System Component recursively (going up into the parent Folder/SG)? -->
    <add key="SystemComponentRecursive" value="true"/>

    <!-- When merging several System Components, should it override values for the same key? -->
    <add key="SystemComponentOverride" value="true"/>
  </appSettings>
</configuration>

The configuration keys have the following meaning and possible values:
  • SystemComponentCacheMinutes - the amount of minutes to keep a loaded Configuration object into memory cache;
  • SystemComponentLocation - the location where the configuration Component is located in Tridion CM. Possible multiple values comma-separated are:
    • Publication - denotes the configuration Component is to be read from the Publication Metadata. Specify then also key SystemComponentField;
    • Current - denotes the configuration Component to be read from the Metadata of the current item's Organizational Item (so either its parent Folder or Structure Group). The current item is the item for which the Event System code is performing the action. Specify then also key SystemComponentField;
    • TcmUri - represents an TcmUri string to read the configuration Component from;
    • WebDavUrl - represents a WebDavUrl string to read the configuration Component from;
  • SystemComponentField - comma separated field names to attempt to read the configuration Component from. Each of these values are attempted to be accessed in the metadata of the Organizational Item or Publication. The configuration Component is assumed to be a Component Link from this metadata field to the actual configuration Component;
  • SystemComponentRecursive - string denoting a boolean value (true or false), which instructs whether the configuration Component should be attempted to be read recursively up into the parent Organizational Item until the Root is found;
  • SystemComponentOverride - string denoting a boolean value (true or false), which instructs whether the configuration values found should be overridden in case the same configuration key is encountered. If false, then the value of an existing key will be set once and shall not be overridden;

Usage

Use the static method GetInstance(RepositoryLocalObject) to get the latest up-to-date ConfigurationManager singleton instance. This method also checks the cache and reloads the configurations when/if needed. Execute this method from each Event System interception (call-back) method.

[TcmExtension("Yet Another Event System")]
public class EventSystem : TcmExtension {

    private ConfigurationManager configManager;

    public EventSystem() {
        EventSystem.Subscribe<Component, CheckInEventArgs>(OnComponentCheckIn, EventPhases.Initiated);
        EventSystem.Subscribe<TemplateBuildingBlock, CheckInEventArgs>(OnTBBSavePre, EventPhases.TransactionCommitted);
    }

    private void OnComponentCheckIn(Component component, CheckInEventArgs args, EventPhases phase) {
        configManager = ConfigurationManager.GetInstance(component);
    }

    private void OnTBBSavePre(TemplateBuildingBlock tbb, CheckInEventArgs args, EventPhases phase) {
        configManager = ConfigurationManager.GetInstance(tbb);
    }
}


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