Implementing a Configuration Loader

The configuration IO mechanism of the NLML depends on a tree of configuration items, where each has a name and a value and any number of sub items. Configuration Loaders are responsible for loading the configuration of a certain handler from those tree.

To create a configuration loader, simply create a new class and derive from eExNLML.IO.HandlerConfigurationLoader.

Start with implementing a constructor, which calls the base constructor and also stores a reference to the Traffic Handler for which this configuration loader is responsible:

private YourHandler thHandler;

public YourConfigurationLoader(TrafficHandler thHandler)
: base(thHandler)
    this.thHandler = (YourHandler)thHandler;

Then, override the ParseConfiguration method, to parse the configuration. This method has two parameters. First, a dictionary which contains all configuration items at root level, and second, the environment.

/// <summary>
/// This method must be overriden by any derived class. It must configure the given traffic handler according to the given name value configuration items.
/// </summary>
/// <param name="strNameValues">A dictionary filled with name value items which store the configuration to apply to your traffic handler</param>
/// <param name="eEnviornment">The environment to associate with the traffic handler</param>
protected abstract void ParseConfiguration(Dictionary<string, NameValueItem[]> strNameValues, IEnvironment eEnviornment);

When parsing, don't forget that each configuration item (NameValueItem) can have any number of sub-items. For parsing common data types, simply use the methods which are provided by the eExNLML.IO.ConfigurationParser class. Since the configuration can also contain many items with the same name, the parsing methods are written to work with arrays. If a property is not supposed to be contained more than once in the configuration, simply use the first value in the array.

protected override void ParseConfiguration(Dictionary<string, NameValueItem[]> strNameValues, IEnvironment eEnviornment)
    //Parsing root configuration

    if (strNameValues.ContainsKey("PropertyA"))
        thHandler.PropertyA = ConfigurationParser.ConvertToBools(strNameValues["PropertyA"])[0];

    if (strNameValues.ContainsKey("PropertyB"))
        thHandler.PropertyB = ConfigurationParser.ConvertToInt(strNameValues["PropertyB"])[0];

    //Parsing nested configuration
    if (strNameValues.ContainsKey("MultipleNestedProperty"))
        //For each configuration item with the name "MultipleNestedProperty" 
        foreach (NameValueItem nvi in strNameValues["MultipleNestedProperty"])
            //Access sub items of the configuration item with the name "MultipleNestedProperty"
            IPAddress ipAddress= ConvertToIPAddress(nvi["Address"])[0];
            Subnetmask smMask = ConvertToSubnetmask(nvi["Mask"])[0];
            thHandler.Add(ipaAddress, smMask);

The ParseConfiguration method is called by the NLML engine once when loading is done, after the initialization of the HandlerController.

Last edited May 1, 2011 at 11:50 AM by emiswelt, version 2


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