cXML is finally here!
In mid-May 1999, cXML Version 0.91 became available for public download from cxml.org. I downloaded, printed, and dissected the PDF version in response to reader demands for additional information about cXML.
In this week''s one year anniversary edition, we take an in-depth look at how cXML''s structure provides support for secure business-to-business exchange via the Web.
The draft specification is divided into six sections:
- Protocol specification
- Basic and common elements
- Order definitions
- PunchOut definitions
- Catalog definitions
- cXML V1.0 XML documents (.dtd and .mod files)
According to the specification''s introduction, cXML is geared to provide ease of implementation and is encouraged for building prototype applications to work out remaining wrinkles with inter-company communications and purchasing.
Protocol Specifications
CXML follows the request/response message pair model for sharing cXML documents. It also provides for special purpose one-way messaging that''s primarily needed for PunchOut processing. Message pairs are bound to the HTTP protocol and are analogous to TCP over IP. One-way messages are analogous to using UDP over IP. Messages are placed on remote servers using the HTTP-POST operation then wait in-turn for a response.
CXML messages are divided into two major parts, header and message data. Header elements provide for addressing information and for sharing authentication credentials. Message data elements consist of specific cXML
request and responses and their associated parameters or attributes.
A rough form of a cXML request message appears as:
<cXML>
<Header>
...
</Header>
<Request>
...
</Request>
</cXML>
A response cXML messages appears as:
<cXML>
<Response>
...
</Response>
</cXML>
Notice there is no header element in a response message since all responses travel using the same HTTP request path that initiated the work.
The < cXML > and < /cXML > tag is present in all cXML transactions. A typical tag appears
as follows:
<cXML verison="0.9" payloadID="1234567.4567.5678@test.ariba.com"
timestamp="1999-03-31T18:39:09-08:00">
payloadID represents a unique number that''s used for logging purposes and for identifying messages. Ariba recommends using the following attributes to construct the payloadID element:
datetime.process.id.randomnumber@hostname
cXML headers incorporate 3 elements:
The sender element includes a credentials element to help remote hosts trust the origin of cXML messages it receives.
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