Monday, December 29, 2008

Web Application Framework

A web application framework is a software framework that is designed to support the development of dynamic websites, Web applications and Web services. The framework aims to alleviate the overhead associated with common activities used in Web development. For example, many frameworks provide libraries for database access, tem plating frameworks and session management, and often promote code reuse.

As the design of the World Wide Web was not inherently dynamic, early hypertext consisted of hand-coded HTML that was published on web servers. Any modifications to published pages needed to be performed by the pages' author. To provide a dynamic web page that reflected user inputs, the Common Gateway Interface (CGI) standard was introduced for interfacing external applications with web servers. CGI could adversely affect server load, though, since each request had to start a separate process.

Programmers wanted tighter integration with the web server to enable high traffic web applications. The Apache HTTP Server, for example, supports modules that can extend the web server with arbitrary code executions (such as mod Perl) or forward specific requests to a web server that can handle dynamic content (such as mod jk). Some web servers (such as Apache Tomcat) were specifically designed to handle dynamic content by executing code written in some languages, such as Java.

Monday, December 22, 2008

Structure Of Web Application

Applications are usually broken into logical chunks called "tiers", where every tier is assigned a role. Traditional applications consist only of 1 tier, which resides on the client machine, but web applications lend themselves to a n-tiered approach by nature. Though many variations are possible, the most common structure is the three-tiered application. In its most common form, the three tiers are called presentation, application and storage, in this order. A web browser is the first tier (presentation), an engine using some dynamic Web content technology (such as ASP, ASP.NET, CGI, Cold Fusion, JSP/Java, PHP, Perl, Python, Ruby on Rails or Struts2) is the middle tier (application logic), and a database is the third tier (storage). The web browser sends requests to the middle tier, which services them by making queries and updates against the database and generates a user interface.

For more complex applications, a 3-tier solution may fall short, and you may need a n-tiered approach, where the greatest benefit is breaking the business logic, which resides on the application tier, into a more fine-grained model. For example, creating a separate business logic tier. Or adding an integration tier that separates the data tier from the rest of tiers by providing an easy-to-use interface to access the data. For example, you would access the client data by calling a "list clients" function instead of making a SQL query directly against the client table on the database. That allows to replace the underlying database without changing the other tiers.

There are some who view a web application as a two-tier architecture. This can be a "smart" client that performs all the work and queries a "dumb" server, or a "dumb" client that relies on a "smart" server. The client would handle the presentation tier, the server would have the database (storage tier), and the business logic (application tier) would be on one of them or on both. While this increases the scalability of the applications and separates the display and the database, it still doesn't allow for true specialization of layers, so most applications will outgrow this model.

Monday, December 15, 2008

Technical considerations

A significant advantage of building web applications to support standard browser features is that they should perform as specified regardless of the operating system or OS version installed on a given client. Rather than creating clients for MS Windows, Mac OS X, Linux, and other operating systems, the application can be written once and deployed almost anywhere. However, inconsistent implementations of the HTML, CSS, DOM and other browser specifications can cause problems in web application development and support. Additionally, the ability of users to customize many of the display settings of their browser (such as selecting different font sizes, colors, and typefaces, or disabling scripting support) can interfere with consistent implementation of a web application.

Another approach is to use Adobe Flash or Java applets to provide some or all of the user interface. Since most web browsers include support for these technologies (usually through plug-ins), Flash- or Java-based applications can be implemented with much of the same ease of deployment. Because they allow the programmer greater control over the interface, they bypass many browser-configuration issues, although incompatibilities between Java or Flash implementations on the client can introduce different complications. Because of their architectural similarities to traditional client-server applications, with a somewhat "thick" client, there is some dispute over whether to call systems of this sort "web applications"; an alternative term is "Rich Internet Application" (RIA).

Monday, December 8, 2008

Feature Driven Development

FDD was initially devised by Jeff De Luca to meet the specific needs of a 15 month, 50 person software development project at a large Singapore bank in 1997. Jeff De Luca delivered a set of five processes that covered the development of an overall model and the listing, planning, design and building of features. The first process is heavily influenced by Peter Coad´s approach to object modeling. The second process incorporates Peter Coad's ideas of using a feature list to manage functional requirements and development tasks. The other processes and the blending of the processes into a cohesive whole is a result of Jeff De Luca's experience. Since its successful use on the Singapore project there have been several implementations of FDD.

The description of FDD was first introduced to the world in Chapter 6 of the book Java Modeling in Color with UMLby Peter Coad, Eric Lefebvre and Jeff De Luca in 1999. In Stephen Palmer and Mac Felsing´s book A Practical Guide to Feature-Driven Development[2] (published in 2002) a more general description of FDD, decoupled from java modeling in color, is given.

The original and latest FDD processes can be found on Jeff De Luca´s website under the ´Article´ area. There is also a Community website available at which people can learn more about FDD, questions can be asked, and experiences and the processes themselves are discussed.

Friday, November 7, 2008

EPA Giving Shorter Shrift to Science

If the U.S. Environmental Protection Agency is known for one thing, it’s missing deadlines. The agency regularly misses deadlines for updating health standards and just as regularly gets sued by environmental groups over it.

However, EPA has now found the answer to this problem. If lengthy scientific review and debate is causing the agency to miss its deadlines, then cut back on the science and beef up the role of EPA’s political appointees (who presumably already know what they want and can speed things along to achieve it, science or no).

Monday, October 20, 2008

web application

In software engineering, a web application or webapp is an request that is accessed via web browser over a network such as the Internet or an intranet. It is also a computer software submission that is coded in a browser-supported language and dependent on a common web browser to render the appliance executable.

Web applications are trendy due to the ubiquity of a client, at times called a thin client. The ability to update and keep web applications without distributing and install software on potentially thousands of client computer is a key reason for their popularity. Common web applications comprise webmail, online retail sales, online auctions, wikis, massively multiplayer online role-playing games and many other function.

Monday, October 13, 2008

Ajax :Disadvantages

* Dynamically shaped pages do not register themselves with the browser's history engine, so clicking the browser's "back" button would not return the user to a previous state of the Ajax-enabled page, but would instead return them to the last page visit before it. Workarounds include the use of unseen IFrames to trigger change in the browser's history and varying the anchor bit of the URL when AJAX is run and monitoring it for change.

* Dynamic web page update also makes it hard for a user to bookmark a particular state of the application. Solutions to this problem exist, many of which use the URL fragment identifier to keep track of, and allow users to return to, the request in a given state.

* Because most web crawlers do not carry out JavaScript code, web applications should give an alternative means of accessing the happy that would normally be retrieve with Ajax, to allow search engines to index it.

* Any user whose browser does not hold Ajax or JavaScript, or simply has JavaScript disable, will not be able to use its functionality. Similarly, devices such as mobile phones, PDAs, and screen readers may not have hold for JavaScript or the XMLHttpRequest object. Also, screen readers that are clever to use Ajax may still not be able to properly read the dynamically generate content.

* The same origin policy prevents Ajax from being used across domains, although the W3C has a draft that would allow this functionality.

* The lack of a standards body behind Ajax income there is no widely adopted best do to test Ajax applications. Testing gear for Ajax often do not appreciate Ajax event models, data models, and protocols.

Sunday, October 5, 2008

Ajax Advantages

In many cases, the pages on a website consist of much satisfied that is common between them. Using traditional methods, that content would have to be reloaded on every demand. However, using Ajax, a web application can request only the contented that needs to be updated, thus radically reducing bandwidth usage and load time.

The use of asynchronous needs allows the client's Web browser UI to be extra interactive and to respond quickly to inputs, and section of pages can also be reloaded individually. Users may recognize the application to be faster or more receptive, even if the application has not distorted on the server side.

The use of Ajax can reduce relations to the server, since scripts and style sheet only have to be request once.

Monday, September 29, 2008

Technologies :Ajax

The term Ajax has come to stand for a broad group of web technologies that can be used to apply a web application that communicates with a server in the backdrop, without interfering with the current state of the page. In the article that coined the term Ajax, Jesse James Garrett explains that it refers specifically to these technologies:

* XHTML and CSS for presentation

* the Document Object Model for dynamic display of and interaction with data

* XML and XSLT for the interchange and manipulation of data, respectively

* the XMLHttpRequest object for asynchronous communication

* JavaScript to bring these technologies together

Since then, though, there have been a number of developments in the technology used in an Ajax application, and the definition of the term Ajax. In particular, it has been renowned that:

* JavaScript is not the only client-side scripting language that can be used for implement an Ajax application. Other languages such as VBScript are also capable of the necessary functionality.

* The XMLHttpRequest object is not necessary for asynchronous announcement. It has been noted that IFrames are capable of the same consequence.

* XML is not required for data exchange and therefore XSLT is not required for the treatment of data. JavaScript Object Notation is often used as an alternative format for data exchange, although extra format such as preformatted HTML or plain book can also be used.

Sunday, September 21, 2008


Ajax is combination of both asynchronous JavaScript and XML, or AJAX, is a group of interconnected web development technique used for creating interactive web application or rich Internet application. With Ajax, web application can recover data from the server asynchronously in the setting without intrusive with the display and behavior of the obtainable page. Data is retrieve using the XMLHttpRequest object or all the way through the use of Remote Scripting in browsers that do not hold it. Despite the name, the use of JavaScript, XML, or its asynchronous use is not necessary.

Monday, September 8, 2008

Raga system

A raga in Carnatic music prescribes a set of rules for build a melody very similar to the Western concept of mode. It specify rules for actions up and down, the scale of which notes should figure more and which notes should be used more scarcely, which notes may be sung with gamaka, which phrases should be used, phrases should be avoid, and so on. In effect, it is a series of necessary musical events which must be observed, either absolutely or with a particular frequency.

In Carnatic music, the sampoorna ragas are classify into a method called the melakarta, which groups them according to the kinds of comments that they have. There are seventy-two melakarta ragas, thirty six of whose madhyama is sadharana, the residual thirty-six of whose madhyama is prati. The ragas are group into sets of six, called chakras group according to the supertonic and mediant scale degrees. There is a scheme known as the katapayadi sankhya to establish the names of melakarta ragas.

Ragas may be divided into two modules: janaka ragas and janya ragas. Janya ragas are subclassified into different categories themselves.

Sunday, August 24, 2008


Swara refers to a kind of musical sound that is a sole note, which defines a relative location of a note, rather than a distinct frequency. Swaras too refer to the solfege of Carnatic music, which consist of seven notes, "sa-ri-ga-ma-pa-da-ni" . These names are abbreviation of the longer names shadja, rishabha, gandhara. madhyama, panchama, dhaivata and nishada. Unlike other music system, every part of the solfege has three variant. The exceptions are the drone notes, shadja and panchama , which contain only one form; and madhyama , which has two form. A 7th century stone writing in Kudumiyan Malai in Tamil Nadu shows vowel change to solfege secret code with ra, ri, ru etc. to signify the higher quarter-tones. In one scale, or ragam, there is regularly only one variant of each note here. The exceptions live in "light" ragas, in which, for artistic effect, there may be two, one rising and another downward.

Sunday, August 17, 2008


Sruti generally refers to musical pitch. It is the near equivalent of a tonic in Western harmony; it is the message from which all the others are derivative. It is also used in the logic of grade pitches in an octave. While there is a countless number of sound falling within a size in Carnatic music, the quantity that can be notable by auditory perception is twenty-two. In this sense, while shruti is resolute by auditory observation, it is also an appearance in the listener's mind.