The most important part of a header handler signature is a HANDLE parameter that references the header of a SOAP message. This handle references a SOAP header object that maps to the parsed XML of the actual SOAP message header in the form of a DOM tree. The SOAP header object implements part of an object model that allows you to directly access the XML content of the SOAP header without having to parse it out of the SOAP message. Figure 1 shows the relationship between the SOAP header object model and the parsed XML DOM tree using the SOAP header described in the preceding section.

The complete SOAP header object model includes two types of objects:

The SOAP header object handle also provides attributes that return information about the name of the header and the number of header entries that the header contains.

In the above figure, one SOAP header-entryref object references the Transaction header entry and another object references the OrderInfoID header entry. When working with a SOAP header, you can also use a single SOAP header-entryref object to reference all of the header entries in a SOAP header, one at a time. The SOAP header-entryref object handle provides several ABL attributes and methods that allow you to inspect and modify the contents of the header entry that it references. The attributes return the values of standard SOAP attributes contained in the header entry element, such as the name and namespace of the header entry.