do I have to register a XML schema in XSR before using it for validation?

Yes, A XML schema has to be registered in XSR before it can be used for validation.

OK...
I want to register a XML schema in XSR. May I know how to do this?

XML schema registration involves three steps. First you have to register the primary schema document. It can be done as given below:
Step1: REGISTER XMLSCHEMA http://test FROM /db2/samples/schema/test.xsd AS test.test1;

It will register the primary schema document test.xsd with the XSR. The fully-qualified name of the test.xsd schema is /db2/samples/schema/test.xsd. /db2/samples/schema directory is the local directory where the test.xsd schema document is stored on the system. The schema location is specified using the URL http://test. This XML schema is identified as test.test1.

If XML schema involves multiple schema documents, it can be added to the registered primary document as given below:
Step2: ADD XMLSCHEMA DOCUMENT TO test.test1 ADD header.xsd FROM /db2/samples/schema/header.xsd;

Finally registration process can be completed as given below:
Step3: COMPLETE XMLSCHEMA test.test1;
You can check http://www-128.ibm.com/developerwork...Validation.pdf for more information on this.

What is primary schema document?

An XML schema is a collection of one or more XML schema documents. Of this collection, one document must be designated as the primary schema document. The primary schema document is at the top of the hierarchy with respect to the import and includes dependencies. It includes and/or imports other documents in the schema, which might further include and/or import other schema documents.

Please give more details about query given in Step 1 for registering primary schema document? I seem to have some problems there.

In order to register the document, the fully-qualified file name for the schema document is needed. Fully-qualified name means the file system path of where the document is stored. An SQL identifier also needs to be provided so that the XML schema can later be identified and used for validation. The user can choose any valid SQL two-part name to identify the XML schema. Using meaningful names that help in identifying the XML schema is recommended. Additional information like the schema location of the XML schema can also be provided during registration. Schema location is a URL that identifies and indicates where the schema document is located. You can check http://www.ibm.com/developerworks/db...m-0603saracco/ for more information on this.

Does DB2 validate the schema documents before registering it with XSR?

The schema documents are analyzed and any mismatches between the schema locations provided in the 2nd step and schemaLocation values provided in the import and/or include tags in the schema documents are discovered. If the schema documents are not well-formed or there are schema location mismatches, an error is issued to the user and the schema does not get registered with the XSR.