Posts tagged xquery
Implementing Web Services backed by a Database PL/SQL API using the Oracle Service Bus
1This article accompanies an article on the Architecture section of Oracle Technology Network (OTN): Implementing the Enterprise Service Bus Pattern to Expose Database Backed Services. It provides a detailed description of the implementation of the ESB architecture design pattern – the same that is introduced in the article on OTN – using Oracle Service Bus. This OSB based implementation is in terms of structure, architecture design and functionality the replica of the pure Java based implementation described in the OTN-article. OSB adds productivity, agility and many run time administrative benefits over the pure Java solution.
The challengeThe challenge the organization – let us call them Stuff Inc. – is facing is simple and common: external parties have requested access to information through Web Services. This information is held in the enterprise (Oracle) database at Stuff Inc.
The architecture team decides that the implementation of the service should be done according to the ESB architecture pattern.
Their initial implementation is based on custom Java Classes, XSLT stylesheets and JDBC calls.
After some time having worked with this initial set up, they decide to More >
Running XQuery from Java applications using the XQJ API and the Oracle XDK implementation
1While preparing for the new SOA for Java Professionals training program at AMIS, I was recently working on a section discussing XQuery and more specifically the ability to use XQuery from Java as an alternative to JAXB binding to POJOs on the one hand and DOM based XPath searches on the other.
The XQJ API for XQuery support from Java is relatively new and unknown. Implementations of the API are not yet part of Java 6 SE (I am not sure about Java 7) and the number of resources on the internet is still limited.
This article shows the steps for running a simple Java program for inspecting an RSS feed and printing titles for RSS items that concern Java. It also shows how to configure a Java application in JDeveloper 11g using the Oracle XDK implementation of XQJ.
Ways to instantiate a variable in Oracle Service Bus based on a static XML document
4Today we had an interesting exploration into the many ways available in the Oracle Service Bus to load a piece of XML into a variable in a message flow – to use as the source for populating part of a to-be-forwarded request message to the business service or for enriching the response message. Even such a seemingly straightforward task turned out to have a number of ways to approach, each with their own merits and complexities.
The various approaches we uncovered in a space of ten minutes or so:
- use a static expression in an Assign action, simply copying the XML content into the variable
- use the function fn:doc that can load XML from a local file and assign the XML to a variable that way
- introduce the file adapter to load the XML file from the local file system and assign it to a variable; this would also support non-XML formats – like comma separated values – that can be converted to XML
- use the database adapter (or the fn-bea:execute-sql) to retrieve the XML content from a relational database
- store the XML content in an XQuery transformation
- do any of the above and wrap it inside a Proxy Service that can be invoked from from other services, potentially governed by the service More >
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