XMLNSC validation

Enabling XML Schema validation in a message flow

You must complete the following tasks to construct a message flow that validates an XML document in accordance with an XML Schema:

• Enable validation at the appropriate point in the message flow. This is typically achieved by setting the Validate property of the appropriate node to Content and Value. See Validating messages.
• Ensure that all required XML Schema files are deployed. See Deploying XML Schemas later in this section.
• If the XML Schema files are deployed in a message set, you must also supply the name of the message set. Typically, you specify the message set by selecting the Message Set property on a message flow node. If the parser is being invoked from a programming language such as ESQL or Java™, the message set must be specified in the parameters of the function call.

Deploying XML Schemas

XML Schemas can be deployed within an application, in a library that is referenced by an application, or in a message set.

If the schemas are deployed as part of the application, they must be included in one of the projects that are referenced by the application.

If the schemas are deployed in a library, the application must reference that library, even if it will be deployed as part of a different application.

If the schemas are deployed in a message set, you must complete the following steps.

All XML Schemas that are used by IBM® Integration Bus must be created as message definition files within a message set.

To create and deploy a message set for XML Schema validation:

1. Create a new message set or locate an existing message set.
2. Ensure that the message set has its Default message domain set to XMLNSC, or that the XMLNSC check box under Supported message domains is selected, to indicate that the message set supports the XMLNSC domain.
3. Create a message definition file in the message set to represent your message. If you have an existing XML Schema or DTD that describes your message, you can import it. You can repeat this step for each message that you want to validate.
4. Add the message set to a broker archive (BAR) file, which generates the required XML Schema in a file with extension .xsdzip, and deploy the BAR file to the broker.

Standards compliant validation

XMLNSC validation complies fully with XML Schema v1.0 as defined in the specifications that are available at http://www.w3.org/TR/xmlschema-1/ and http://www.w3.org/TR/xmlschema-2/, with the following minor exceptions:

• Any floating point value that is smaller than 10E-43 is treated as zero.
• Any member of a group or complex type, that has both minOccurs > 1024 and maxOccurs > 1024, is validated as if minOccurs = 0 and maxOccurs is unbounded.

Validating XML v1.1 documents

You can validate documents that conform to the XML v1.1 specification, but support is limited by the fact that the XML Schema v1.0 documents must conform to XML v1.0.

As an example, you cannot always declare an XML v1.1 tag name in XML Schema v1.0. This limitation is not imposed by the XMLNSC parser implementation; it is a limitation of XML Schema v1.0.

Interpreting validation errors

A validation error is an error that results when the XML document breaks the rules that are defined in the XML schema. The XML Schema standard specifies exactly what these rules are, and how they should be applied. Validation errors that the XMLNSC parser issues contain information that links the error to the XML Schema rule that has been violated.

XML schema validation error '[cvc-error key: error description]'

'cvc-minInclusive-valid: The value "2" is not valid with respect to the minInclusive facet 
with value "3" for type "po:itemCountType".' 

'cvc-complex-type.2.4.a: Expecting element with local name "numItems" but saw "totalValue".' 

Example 1: Open http://www.w3.org/TR/xmlschema-1/ and search for ‘cvc-minInclusive-valid'. Follow the link to the XML Schema rules for the minInclusive facet.

Example 2: Open http://www.w3.org/TR/xmlschema-1/ and search for ‘cvc-complex-type'. Follow the link to the XML Schema rules for validating the content of a complex type. In this case, the error key contains extra information. The ‘2.4.a' refers to the exact sub-rule that was violated. It should not be included when searching for the rule.

If the XML Schema specification does not provide enough information, you can find more information using a search engine. The XML Schema standard is very widely used, and many online tutorials and other resources are available.