Tutorials XMLExtensive markup language is the language which presents data in a human readable form of text. The data can be anything from a purchase order or a stock quote or weather radar or a flight schedule it can be represented using XML. XML is very similar to HTML in its functionalities because even XML uses the open tag and the close tag.
But the difference between the both is that the HTML has a set of fixed tags and you have to use something from the specified list and in XML you can use your own tags. These tags can be something which is related to the industry you are in or you can also come up with your own tags and define them. The data that is presented in XML is called an XML document which can be quantified as one unit of data. For example each purchase quote can be called one XML document.
When these XML documents are transformed form one place to another or one system to another system in the packets it is called a datagram. XML documents are usually well structured and well formed documents because they follow the syntax rules correctly and follow the standards exactly the way they are set such as the rule that the start tag and the end tag should always match with each other. This way the XML tags allow you to create a clean and structured form of data.
Oracle offers something called the MXL developer's kit or the XDK which provides all the functionalities of XML in the Oracle 8i environment and even in the Oracle 9i environment. The intermediate text which has started in the Oracle 8i has been built around XML and has an increased awareness for being compatible with XML.
In addition to all of these the developer also includes a lot of functions which were built to work along with XML in coalition. But people who work on Oracle versions which were released before the oracle 8i came into picture cannot directly use the XML but for these people a version of XML called the PLSXML which is a utility based on ML is available and gives the users the same advantages XML gives to oracle 8i users in terms of functionality for the Sequel Applications.
Ever since Oracle 8i was released, the XML developer's kit has come along for Oracle developers. The XML Developer's kit has basically integrated itself into the database ad automatically installs itself along with the database whenever it is installed. PL/SQL can also be used to access the XML developers kit. Even programming languages like Java, C and C++ are used to access the XML developer's kit.
Sequel Applications have a limitation that they have to run inside the database only for example programs like the packages or stored procedures if you have to access the XML developer's kit. Where as the java applications may be inside the database or outside the database it doesn't matter to the XML developer's kit. C and C++ by default are located outside the database and there is no other possibility that exists in their case.
If you have to access the XML developer Kit from a Pl or Sequel or even Java applications for that matter you will have to install the Java virtual machine or JVM and also known as the Jserver. It is quite contradictory that you have to install a jserver or Oracle Java virtual machine installed in order to be able to use the java virtual machine because the XML developers kit was written in Java, this fact has given birth to the need for JVM. Oracle puts wrappers from PL/SQL on the java code so that it is accessible from the PL/SQL.
The XML developers Kit includes an XML parser along with an XSLT processor and also an XPath engine which comes with XSQL page processor and a servlet and additional XML SQL utility. The XDK and the XML parser and the XSLT processor were implemented by Oracle to make itself more adaptable to XML so that it can work cohesively with XML but the XSQL page processor and the XML SQL utility are Oracles own feature which were introduced long with the borrowed features. These elements function together in coordination.
However the XSQL page can be accessed only through the Java applications or the Java virtual machine. In the previous versions of the XDK the XML SQL utility was a tool by itself separate from the XDK and also had to be installed separately, but now it has been built into the XDK and can be installed while the XDK is being installed.
Next Page: XML Parser, XSLT Processor, and XPath Engine
