Programming Web Services with Perl

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Defining UDDI

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In this example, the instance info structure refers to a tModel that defines the inter-

face by referring to a URI where the WSDL file can be retrieved. There’s no need to

define a key/value pair just to refer to the existing model structure so that clients of

the service can find the description. The only thing that must appear is the

tModelKey

attribute, which refers to the tModel by its UUID. There is allowance for an optional

description element (not shown in this example) followed by the instanceDetails

element. This element contains information mainly for end users more than for auto-

mated clients. It allows the publisher of the record to make notes about what he is

referring to and why. The

overviewDoc block allows a description and a URL to be

provided.

Following the overview information is the

instanceParms element. This element is

very badly documented in the UDDI specifications. In Version 1, the content is

defined as either a URL or an XML string, which is to be namespace-qualified into a

namespace other than that of UDDI itself. But the XML Schema that describes the

structure of the UDDI elements forbids embedded XML. This was noted and cor-

rected in the Version 2 specification. Here, a simple URL is shown as an example.

The role and content aren’t defined by UDDI; they are negotiated between clients

and providers. The URI may be line-delimited key/value pairs, an XML Schema, etc.

Publish and Query Interfaces

UDDI uses SOAP as the actual communications-level protocol for managing requests

and responses between clients and servers. This is helpful because it keeps end users

from having to learn yet another protocol for their applications.

The programming interface is roughly divided into two sections: the routines that

publish data to a registry and those that query a registry for information. We limit

coverage here to basic details because of the complex nature of the elements

involved. For greater depth, refer to the Programmer API documents on the UDDI

home page at http://www.uddi.org.

a WSDL service definition is provided to the

client. The tModel referenced should have been

created already, with the URI of the WSDL file.

</description>

<overviewURL>

http://localhost/wishlist.wsdl

</overviewURL>

</overviewDoc>

<instanceParms>

http://localhost/parms.txt

</instanceParms>

</instanceDetails>

</tModelInstanceInfo>

Example 10-5. Referencing the tModel for WSDL description (continued)