Support for Literal Values

ILOG Rules for .NET User Guides > Rule Studio > Defining Business Object Models > Support for Literal Values

Support for Literal Values

You can represent some types of the business object model as literal values.

The following properties are defined on a type and are used to define a literal value:

Value Converter

The value converter retrieves the values for the type and converts them into a form that the business object model can use to display them in a business rule.

Value Descriptor

The Value Descriptor property of a type provides information for the business rule language parser. This property informs the parser what the textual form of the value is: a number, a set of characters between quotes, a $ sign preceding a number, and so on.

The Value Descriptor property can be specified using either an existing literal value type (Number, String, Date) or a Custom Value Category. If the Value Category is Custom you must provide a regular expression and a default value. Otherwise, the value is derived from an existing literal value type by adding a prefix and a suffix.

Value Editor

An optional property to customize the user interface in order to edit values. The property value must be a subclass of System.Drawing.Design.UITypeEditor. Note that custom value editors are only supported in the Intellirule Editor within Rule Studio and Rule Solutions for Office.

The Value Converter, Value Descriptor, and Value Editor properties are edited in Rule Studio by selecting the BOM type in the BOM View, and setting the value of the property through the property grid.

You must build your solution or click Refresh in the BOM View toolbar so that the changes are taken into account.

To create the type

The type must be implemented as a structure and must:

have a TypeConverterAttribute attribute that associates the type with its value converter (this attribute is required to locate the converter at runtime)
override GetHashCode() and Equals(object)and overload the equality and inequality operators

To define the value converter

Create a value converter.

You must implement a type converter class. This class must:

inherit from System.ComponentModel.TypeConverter
override the ConvertTo and ConvertFrom methods to support conversion to and from a string

Optionally, if you want to define a domain, override the GetStandardValuesSupported and the GetStandardValues methods. See Creating Dynamic Domains.

Deploy the assembly.

Create a signed assembly containing the type and the type converter.
Add the assembly to the Global Assembly Cache.

At runtime you can also use the Windows Shell command, xcopy, to deploy the assembly to the application directory on the target machine rather than putting the assembly in the GAC.

In your rule application, explicitly load the value converter assembly.

Explicitly loading the value converter ensures that the rule engine can find the value converter assembly at runtime. For information on how to explicitly load an assembly for your execution environment, see Loading the Rule Engine Assemblies.

Set up the business object model.

Add the type to the business object model.
In the Business Object Model View, select the type, select the Value Converter property in the Properties window of the Business Object Model member, and then set the value converter class you defined for it.

To set this property you need the assembly-qualified name of the value converter. For example:

Paints.ColorConverter, Paints, Version=1.0.0.0, Culture=neutral, PublicKeyToken=c1dccd2b4ac6fc5f

You can get the public key token for the assembly using the .NET Strong Name utility, sn.exe.

To add the value descriptor

Open the Value Descriptor dialog from the Properties window.
Select String, Number, Date, or Custom for the Value Category:

For existing literal value types, you can select the Automatic Prefix and Suffix checkbox or enter a Prefix or a Suffix by hand.
For a Custom value type, you must enter a regular expression and a default value.

See Also

Support for Literal Values | The Properties of Business Object Model Members

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