SOAP Message Structure

Part:   1   2 

This chapter describes:

• Generic SOAP message structure.
• SOAP fault message structure.

SOAP Message Structure

A SOAP message is an XML document with "Envelope" as the root element with the following structure:

<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
 <env:Header>
  ...
 </env:Header>
 <env:Body>
  ...
 </env:Body>
</env:Envelope>

where "Header" is an optional child element, and "Body" is a required child element.

A "Header" element may contain zero or more "Header Block" elements with the following structure:

 <env:Header>
  <hb0:headBlock0 xmlns:hb0="Uri0">
   ...
  </hb0:headBlock0>
  ...
  <hbN:headBlockN xmlns:hbN="UriN">
   ...
  </hbN:headBlockN>
 </env:Header>

A "Header Block" element must have a name space. It may contain text information and any number of child elements. It may also contain any number of attributes including SOAP predefined attributes. A "Header Block" has the following structure:

  <hb:headBlock xmlns:hb="Uri">
   <hb:child0 encodingStyle="..." role="..." mustUnderstand="..."
    relay="..." ...>
    ...
   </hb:child0>
   ...
   (text)
   ...
   <hb:childN encodingStyle="..." role="..." mustUnderstand="..."
    relay="..." ...>
    ...
   </hb:childN>
  </hb:headBlock>

"encodingStyle", "role", "mustUnderstand" and "relay" are SOAP predefined attributes. We will discuss them later.

A "Body" element has almost no restrictions. It may have text information, any number of attributes and any number of child elements, with the following structure:

 <env:Body ...>
  <bodyChild0 ...>
   ...
  </bodyChild0 ...>
   ...
   (text)
   ...
  <bodyChildN ...>
   ...
  </bodyChildN ...>
 </env:Body>

To give an idea of how a SOAP message looks like, I have copied the example #1 from the SOAP 1.2 specification here:

<?xml version="1.0"?>
<env:Envelope xmlns:env="http://www.w3.org/2003/05/soap-envelope">
 <env:Header>
  <m:reservation xmlns:m="http://travel.example.org/reservation"
     env:role="http://www.w3.org/2003/05/soap-envelope/role/next"
     env:mustUnderstand="true">
   <m:reference>uuid:093a2da1-q345-73pqff98fe8j7d</m:reference>
   <m:dateAndTime>2001-11-29T13:20:00.000-05:00</m:dateAndTime>
  </m:reservation>
  <n:passenger xmlns:n="http://mycompany.example.com/employees"
     env:role="http://www.w3.org/2003/05/soap-envelope/role/next"
     env:mustUnderstand="true">
   <n:name>Herong Yang</n:name>
  </n:passenger>
 </env:Header>
 <env:Body>
  <p:itinerary
    xmlns:p="http://travelcompany.example.org/reservation/travel">
   <p:departure>
     <p:departing>New York</p:departing>
     <p:arriving>Los Angeles</p:arriving>
     <p:departureDate>2001-12-14</p:departureDate>
     <p:departureTime>late afternoon</p:departureTime>
     <p:seatPreference>aisle</p:seatPreference>
   </p:departure>
   <p:return>
     <p:departing>Los Angeles</p:departing>
     <p:arriving>New York</p:arriving>
     <p:departureDate>2001-12-20</p:departureDate>
     <p:departureTime>mid-morning</p:departureTime>
     <p:seatPreference/>
   </p:return>
  </p:itinerary>
  <q:lodging
   xmlns:q="http://travelcompany.example.org/reservation/hotels">
   <q:preference>none</q:preference>
  </q:lodging>
 </env:Body>
</env:Envelope>

(Continued on next part...)

Part:   1   2