Developer Mapping Guide > Mapping Parameters > Parameter Hierarchy
  

Parameter Hierarchy

The parameter hierarchy defines the levels where you can create user-defined parameters.
The hierarchy occurs in the following order:
Workflow parameters
Mapping parameters
Mapplet parameters
Logical data objects
Transformation/data object parameters
A parameter assigned to an object at a higher level in the hierarchy can replace parameters assigned to lower levels in the hierarchy. You can use the hierarchy to override parameters in the following ways:
For example, you can add a reusable transformation to a mapping. To replace parameters in the reusable transformation, you can create mapping parameters to override the transformation parameters. Or, you can expose the transformation parameters as mapping parameters to bind the transformation parameters to mapping parameters. The transformation uses the default mapping parameter values at run time.

Overriding Parameters Using the Parameter Hierarchy

When you create a parameter for a transformation, a logical data object, a mapplet, or a mapping, you can override the parameter by specifying a new parameter for the transformation, logical data object, mapplet, or mapping at a higher level in the parameter hierarchy.
For example, you create a parameter in a transformation. Then you add the transformation to a mapplet. You can either use the default parameter value from the transformation or you can create a mapplet parameter to override the transformation parameter value.
You can also override parameters using a parameter set or a parameter file. The parameters in the mapping use the parameters specified in the parameter set or parameter file. In a parameter set or a parameter file, you can specify only workflow and mapping parameters.

Binding Parameters to Override the Parameters at Run Time

When you add a reusable object to a mapping or workflow, bind parameters to higher-level parameters in the parameter hierarchy to override the default value of the reusable object parameter. At run time, the Data Integration Service applies the higher-level parameter to the reusable object.
For example, you create a reusable transformation and a parameter in the transformation. Then you add the reusable transformation to a mapplet. You can either use the default parameter value from the transformation, or you can bind the transformation parameter to the mapplet parameter. Change the default value for the mapplet parameter to override the default value of the transformation parameter at run time.
To bind user-defined parameters, expose the parameters. For example, if you add a reusable transformation to a mapping, expose the transformation parameters as mapping parameters to bind the transformation parameters to the mapping parameters.
The following image demonstrates how the Data Integration Service binds parameters in Developer tool mappings:
This image shows a diagram of a mapping that contains a transformation, Transformation 1, and a mapplet. The mapplet contains a second transformation, Transformation 2. The mapping has two parameters, Parameter A and Parameter B. Transformation 1 contains one parameter, Parameter C. The mapplet contains one parameter, Parameter D, and Transformation 2 within the mapplet contains a parameter, Parameter E. Parameter E is connected to Parameter D through an arrow. Parameter D is conntected to Parameter A with an arrow. Parameter C is connected to Parameter B with an arrow.
  1. 1. The parameter in the transformation binds to the parameter in the mapplet. The transformation parameter uses the default value of the mapplet parameter at run time.
  2. 2. The parameter in the mapplet binds to the parameter in the mapping. The mapplet parameter uses the default value of the mapping parameter at run time.
  3. 3. The parameter in the transformation binds to the parameter in the mapping. The transformation parameter uses the default value of the mapping parameter at run time.

Use Cases for Overriding Parameters in Mappings

There are different guidelines to override parameters in non-reusable and reusable mapping objects. You can override both non-reusable and reusable object parameters by creating or reconfiguring mapping parameters. For reusable object parameters, you can first expose the object parameters as mapping parameters. Then reconfigure the mapping parameters.
To override mapping parameters, specify a parameter set or parameter file when you run the mapping.

Overriding Non-Reusable Transformation Parameters in Mappings

When you create a non-reusable transformation in a mapping, the transformation parameters are mapping parameters.
To override the default parameter values in the transformation, complete one of the following tasks:
For example, you can create a non-reusable Filter transformation in a mapping and set a parameter for the Filter transformation. The Developer tool duplicates the transformation parameter and creates a mapping parameter. To override the transformation parameter, reconfigure the default value of the mapping parameter, or configure a parameter set or parameter file to override the mapping parameter.

Overriding Reusable Transformation Parameters in Mappings

When you add a reusable transformation to a mapping, the transformation parameters are transformation parameters until the parameters are exposed as mapping parameters. If you expose the transformation parameters as mapping parameters, you bind the transformation parameters to the mapping parameters. The mapping parameters have the same name and type as the transformation parameters. The default value of the mapping parameter uses the instance value of the reusable transformation parameter.
To override the parameter value in a reusable transformation, complete one of the following tasks:
For example, you can set a parameter for a reusable Filter transformation. When you add the reusable Filter transformation to a mapping, you can configure a mapping parameter to override the Filter transformation parameter, or you can expose the Filter transformation parameter as a mapping parameter. If you expose the Filter transformation parameter as a mapping parameter, the Filter transformation parameter binds to a mapping parameter. To override the exposed transformation parameter, reconfigure the default value of the mapping parameter that binds to the transformation. The transformation uses the default value of the mapping parameter at run time.

Overriding Non-Reusable Transformation Parameters in a Reusable Mapplet

When you create a reusable mapplet that contains a non-reusable transformation, the transformation remains non-reusable. If you create a non-reusable transformation in a mapplet, the transformation parameters are mapplet parameters. When you add a reusable mapplet that contains a non-reusable transformation to a mapping, the non-reusable transformation in the mapplet remains a non-reusable transformation in the mapping.
You can expose the mapplet parameters as mapping parameters. When you expose the mapplet parameters, the mapplet parameters bind to mapping parameters, and the non-reusable transformation parameters become mapping parameters.
To override the reusable mapplet parameters, complete one of the following tasks:
To override the non-reusable transformation parameters, complete one of the following tasks: