XMLNSC: Working with XML messages and bit streams

The ASBITSTREAM function

If you code the ASBITSTREAM function with the parser mode option set to RootBitStream to parse a message tree to a bit stream, the result is an XML document that is built from the children of the target element in the normal way. This algorithm is identical to that used to generate the normal output bit stream. Because the target element is not included in the output bit stream, you must ensure that the children of the element follow the constraints for an XML document.

One constraint is that there must be only one body element in the message. You can use a well-formed bit stream obtained in this way to re-create the original tree using a CREATE statement with a PARSE clause.

If you code the ASBITSTREAM function with the parser mode option set to FolderBitStream to parse a message tree to a bit stream, the generated bit stream is an XML document built from the target element and its children. Any DocTypeDecl or XmlDecl elements are ignored, and the target element itself is included in the generated bit stream.

The advantage of this mode is that the target element becomes the body element of the document, and that body element can have multiple elements nested within it. Use this mode to obtain a bit stream description of arbitrary sub-trees owned by an XML parser. You can use bit streams obtained in this way to re-create the original tree using a CREATE statement with a PARSE clause, and a mode of FolderBitStream.

For further information about the ASBITSTREAM function, and some examples of its use, see ASBITSTREAM function.

The CREATE statement with a PARSE clause

If you code a CREATE statement with a PARSE clause with the parser mode option set to RootBitStream to parse a bit stream to a message tree, the expected bit stream is a normal XML document. A field in the tree is created for each field in the document. This algorithm is identical to that used when parsing a bit stream from an input node. In particular, an element named 'XML', 'XMLNS', or 'XMLNSC' is created as the root element of the tree, and all the content in the message is created as children of that root.

If you code a CREATE statement with a PARSE clause with the parser mode option set to FolderBitStream to parse a bit stream to a message tree, the expected bit stream is a normal XML document. Any content outside the body element (such as an XML declaration or doctype) is discarded. The first element created during the parse corresponds to the body of the XML document, and from there the parse proceeds as normal.

For further information about the CREATE statement, and examples of its use, see CREATE statement.