Defining input schemas and output actions for JET transformations

The input schema for a Java™ Emitter Template (JET) transformation describes the input that a transformation expects. When you create a JET transformation project, the New Project wizard creates an input schema with a root element. You can also import an existing input schema into an existing JET project. Existing schemas are Eclipse Modeling Framework core (Ecore) files with the name input.schema in the root of a JET project. Using a valid transformation input schema ensures that the input to the transformation is structurally correct, and enables transformation users to create input with fewer syntax or semantic errors.

Adding elements and attributes to JET transformation input schemas
An element represents an input that is required by the JET transformation. A transformation input schema can contain many elements, and each element in a transformation input schema has a multiplicity of zero-or-more. You can add one or more attributes to elements, and create JET actions that are associated with an element. Attributes further describe elements, and are also required as input to a transformation.
Creating JET actions for JET transformations
You can create associations between exemplar artifacts and the transformation input schema elements. Exemplar artifacts are associated with the input schema elements through transformation output actions, also called JET actions. There are three types of JET actions: file actions, folder actions, and project actions.
Editing parameters of JET actions
The default values of the JET action parameters are based on the exemplar artifact that you specify to create the JET action. You can edit the action parameter values of a JET action in the Properties view, or replace the parameter values with model references.
Replacing JET action parameter values with input model references
You can set the parameters of a JET action to reference the attributes or elements in an input model. When you refine the transformation input schema, JET action parameter values that you select can include XPath expressions that correspond to elements in the transformation input schema. When you run the JET transformation by using an input model, JET replaces the XPath expression with the values in the input model. This functionality enables you to modify the behavior of a JET action based on values in the input model.
Managing derived attributes for JET transformations
Derived attributes enable you to encapsulate calculations that a transformation performs repeatedly. You can also create derived attributes to avoid having values hard-coded in the transformation.
Replacing text in JET templates with input model references
You can find or replace text in a JET template with a JET tag that references a value in the input model.
Editing exemplar text associations in JET transformations
You can add or remove exemplar text that is associated with an input schema element, attribute, or derived attribute. This functionality enables you to easily find instances of the text in the JET templates that the transformation generates. For each occurrence of the text that you specify, a JET Replace marker is inserted in the JET templates that contain the text. You can then use the Eclipse Quick Fix functionality to view valid replacement options to replace the exemplar text with a JET tag.

Parent topic: Transforming models into text using JET transformations and exemplars

Related concepts

JET transformation authoring

Related information

Tutorials for JET transformations