BI/XML Publisher Notes

Before going into more details of XML Publisher, lets have a look at some of the XML standards.

The XML language specification defines the rules for XML document structure and how XML processors should read the document.

The DTD (document type definition) validates an XML document and provides the relationships of elements contained in the document.

XML Namespaces helps us to distinguish elements with different definitions having same name in the XML document.

The XML Path Language (XPath) provides syntax for searching the XML documents.

The Extensible Style Sheet Language (XSL) uses XSLT (Transformations) to transform an XML document to another document.

An XML Schema describes the XML document structure using DTD and namespaces.

Oracle BI Publisher - OPP (Output Post Processor)

The Output Post Processor (OPP) is mainly used to process post actions of concurrent requests. For instance once the concurrent manager finishes running the concurrent program, it will communicate with OPP to apply the XML Publisher template and create the final output. The services run by OPP are managed through OAM (Oracle Applications Manager). A minimum of one OPP process should always be available in the system to process the concurrent request, otherwise OPP will complete with status WARNING. Depending on the availability the concurrent manager may contact local or remote OPP while running a concurrent request. The OPP service is a multi threaded and initiates a new thread for every concurrent request it processes. We can also view more details of OPP service in OAM. So depending on your work, one can manage the workshifts and the number of threads per process to handle the workload.

Oracle BI Publisher Process Flow

As you have seen a brief introduction to BI/XML Publisher in my last post, today let us see the steps involved in processing a report using BI/XML Publisher.

1.Run the desired concurrent program.
2.The concurrent program calls the data template using the XDO (Extensible
data object) engine.
3.The data template calls the SQL query.
4.The query runs in the database and output is converted to XML.
5.XML output is generated by XML engine.
6.The OPP (Output post processor) formats the output based on the XML Publisher
template you have chosen and creates the final output like pdf, word, excel
and web page.
7.Output delivered to the User.

BI/XML Publisher XDO data engine plays an important role in generating the reports.The XMLP Report business service is the interface to this logical component that initiates the Java services to load the JAR files to the JVM. The Oracle BI Publisher XDO Engine then processes the XML data, XSL template to generate the report. We can also configure the XDO engine to create log files that can capture detail information and errors while generating the reports. The log files are more helpful in determining the cause of problems with the JAR files or the Oracle BI/XML Publisher layout templates.