Working with Schemas

webMethods 10.2 | Service Development Help | Working with Schemas

An IS schema is a “free-standing” element

in Package Navigator view that acts as the blueprint or model against which you validate an XML document. The IS schema provides a formal description of the structure and content for a valid instance document (the XML document). The formal description is created through the specification of constraints. An IS schema can contain the following types of constraints:

Structural constraints in an IS schema describe the elements, attributes, and types that appear in a valid instance document. For example, an IS schema for a purchase order might specify that a valid <lineItem> element must consist of the <itemNumber>, <size>, <color>, <quantity>, and <unitPrice> elements in that order.

Content constraints in an IS schema describe the type of information that elements and attributes can contain in a valid instance document. For example, the <quantity> element might be required to contain a value that is a positive integer.

During data validation, Designer compares the elements and attributes in the instance document with the structural and content constraints described for those elements and attributes in the IS schema. Designer considers the instance document to be valid when it complies with the structural and content constraints described in the IS schema.

You can create IS schemas from an XML schema, a DTD (Document Type Definition), or an XML document that references an existing DTD.