Virtual Way

As per the XML Schemas, the sequence tag in the WSDL file specifies a list of sub elements. This list gives an order in which the sub-elements should appear in the SOAP request. If this sequence is not followed, server does not interpret the SOAP request correctly and throws a fault.

It is the responsibility of the SOAP client to follow the WSDL design and construct the SOAP request. Maintaining the sequence of elements is among one of the several points to keep in mind.

To illustrate this using vSphere APIs, while creating an Alarm using CreateAlarm API, one has to follow the sequence when passing properties in the AlarmSpec. To refer the WSDL definition for the AlarmSpec object, click "Show WSDL type definition" below the object:

Thus, ordering of the elements is a major factor in the SOAP requests processing.