Understanding Application Architecture & Role of Java in XML Application Architecture

XML application architecture:

Each and every program starts with a set of specifications. The end user wants a piece of software that does something in particular. In this event the user wants to see some poart of results that are based upon information extracted from an XML file that’s accessed across a network.

The functionality of application can be divided into following steps:

1. Retrieving the data.
2. Parsing the data.
3. Processing the data.
4. Presenting the data.

Retrieving the data:

To retrieve the data users request the XML files must be accessed and read wherever they are located on the network.

Parsing the data:

Once when the data is drawn from the XML file it must be examined and then assigned relevant variables for next step. This is called parsing.

Processing the data:

The parsed data must then be processed to supply the user with the information that is needed. To do this the data is run through appropriate computational process. The result of the computational process extracts the numerical values and gives the required answers to the user.

Presenting the data:

After the data has been retrieved, parsed and processed the result must be formatted attractively and presented in such a way the user can manipulate any how. This format might vary from concern to concern.

Role of Java in XML Application Architecture:

XML provides a universal syntax for java semantics. A developer can create descriptions for different types of data to make the data behave in various ways with java programming code, and can later repeatedly use and modify those descriptions. XML and Java are both portable standards, the result of using the combination of the two technologies is portable, reusable data and portable behavior.

The two main application areas of XML in Java are presentation-oriented publishing and enterprise message-oriented middleware. XML can be combined with Java to produce applications as complex Web documents, dynamic publishing, e-commerce, enterprise application integration, and structured information management ant retrieval. The java features are the competent tool for all tasks that has to be performed in building an XML application.

Java Parsers:

Java a full-fledged programming language has the capacity to muck around with strings of text. Methods of the string objects in strings helps in:
- Extracting a sub string from a larger string.
- Converting a string to a series of pieces and dividing the string at a particular delimiter.
- Chopping the end off a string.
- Attaching two or more strings together.
- Replacing sub strings with other strings.
After the raw XML data is parsed, additional formatting is done to bring the data into suitable format as required by the program being used.

Java processor:

Java has the power to do any calculation or processing operation. If a situation is not possible by Java then a reference from a Java program to a non Java resource can solve this work.

Java displayer:

Java has the capacity to create to create full-featured user interfaces. Java supports a complete suite of text-formatting and graphic tools. The extracted data can be made attractive using Java. Also the data that has to be inserted that can be displayed into some other documents can be done using Java.

Examining XML Parsers for Java:

The features required to examine the XML Parsers in Java are:

· XJ Parser:

XJ Parsers form Data Channel INC. is designed with server-side processing, the XJ Parser provides a complete suite of XML validation and parsing utilities. Its reliable, high-speed tool kit for handling many complex XML transactions. It includes capacity to handle XSL documents, making it to take XML text, get information, the required formatting information to the resulting text for rendering in a web browser.

· P3P Parser:

P3P Parser is a P3P protocol parser and constructor written in Java. The package contains classes and methods for parsing, generating, manipulating and evaluating P3P proposals and responses. It also contains a parser and evaluator for “ A P3P Preference Exchange Language” (APPEL). Platform for Privacy Preferences (P3P) is a protocol that enables the private exchange of personal information on the web. The goal of P3P is to enable web sites to express privacy practices and enable users to exercise preferences over those practices. P3P products will allow users to be informed of site practices (in both machine and human readable formats), to delegate decisions to the computer and allow users to tailor the relationship to specific sites.

· AElfred (Microstar):

AElfred from Microstar software Ltd. is a complete package of Java classes that provides excellent tools for parsing and processing XML data. AElfred is a small, fast, DTD-aware Java based XML parser, which is used in Java applets. It helps the users to add XML support to the applets and applications without doubling the size. AElfred consists of two core class files, with a total size of about 26k, and requires very little memory to run. There is also a complex SAX driver available in this distribution for interoperability.

· IBM’s XML Parser for Java:

IBM’s XML Parser for Java runs on any platform for, which there is a JVM that complies with the Java1.1//Java1.2 standard XML Parser for Java, also called as XML4J has an interface that follows to take a string of XML-formatted text, pick the tags out of it and use the tags as keys for extracting the tagged information. XML Parser for Java supports the XML Namespaces standard.