Key Features of Rich Web based
Application are;
o
Adobe Flash, Flex and Adobe
Integrated Runtime (AIR)
o Microsoft Silverlight.
o Curl (an object-oriented language with embedded HTML markup)
o Google Gears.
o Open Laszlo and WebTop,
o Oracle Web Center
Different technologies
used to develop the client side components of Rich Web based Application are;
o
Node.js web development frameworks
ü Node.js
is an open source server environment
ü Node.js
is free
ü Node.js runs on various
platforms (Windows, Linux,
UNIX, Mac OS X, etc.)
ü Node.js
uses JavaScript on the server
o
Tensor flow
Tensor Flow is an end-to-end open
source platform for machine learning. It has a comprehensive, flexible
ecosystem of tools, libraries and community resources that lets researchers
push the state-of-the-art in ML and developers easily build and deploy ML powered
applications.
o
Symphony web application framework.
Symphony is an
open-source PHP web application framework, designed for developers who need
a simple and
elegant toolkit to
create full-featured web
applications. Symphony is sponsored by SensioLabs. It was developed by
Fabien Potencier in 2005.
o ASP.NET web application framework- What is ASP.NET?
.NET is a developer
platform made up of tools,
programming languages, and libraries
for building many different types of applications.
ASP.NET extends
the .NET developer platform with tools and
libraries specifically for building
web apps.
Key Features of Rich Web based
Application are;
o
Adobe Flash, Flex and Adobe
Integrated Runtime (AIR)
o Microsoft Silverlight.
oCurl (an object-oriented language with embedded HTML
markup)
o Google Gears.
o Open Laszlo and WebTop,
Delta Communication- Rich
Communication model of
the Rich Web based Application. It is
used to communicate with the server-components, to exchange only the needful
dataset – for a
particular feature executed at the time. Once a page is loaded to the browser,
all the communications with the server, for
all the features implemented on that page, can
be done using DC, eliminating page
refreshes until the page is refreshed or redirected to another page, explicitly by the user or by an internal component.
Rich Internet
Applications (RIAs) have
become popular with their increased user experience delivered through
rich GUIs and faster responses. The key concept
behind the fast responses is the Delta-Communication (DC), which enables
the communication of necessary data between
the client and the server components, in either synchronous or asynchronous
modes, supporting both data-pull and push modes There are various Technologies
and Techniques (TTs) available for
developing the DC in RIAs. These TTs have
been already discussed in different forums, and also many tutorials are
available to demonstrate the development of them.
However, proper
comparisons of these TTs are not available towards supporting decision making
in selecting these TTs for the RIA development.
Definition - What does Synchronous Transmission mean?
Synchronous
transmission is a data transfer method which is characterized by a continuous
stream of data in the form of signals which are accompanied by regular timing
signals which are generated by some external clocking mechanism meant to ensure
that both the sender and receiver are synchronized with each other.
Data
are sent as frames or packets in fixed intervals.
Synchronous
transmission is transmission of signals in a fixed interval based on a
predefined clocking signal and is meant for constant and reliable transmission
of time-sensitive data such as VoIP and audio/video streaming.
This
method of transmission is used when large amounts of data need to be
transferred quickly since data is transferred in large blocks instead of
individual characters. The data blocks are spaced and grouped in regular intervals
and preceded by synchronous
characters that a remote device decode and use to synchronize the
connection
between the end points. After synchronization is complete, the transmission can
begin.
Definition
- What does Asynchronous Transmission mean?
Asynchronous
transmission is the transmission of data in which each character is a
self-contained unit with its own start and stop bits and an uneven interval
between them.
Asynchronous transmission is also referred
to as start/stop transmission.
Asynchronous transmission
uses start and stop bits to signify the beginning and ending bits. The additional one at the start and end of a transmission alerts the receiver
to the occurrence of the first character and last character. The asynchronous transmission method is deployed
when data is sent as packets as opposed to in a solid stream. The start
and stop bits have opposite polarity, allowing the receiver to understand when
the second packet of information has been
sent.
The two main characteristics specific to asynchronous
communication are:
Every character is preceded by a start
bit and followed
by one or more stop bits
Spaces between characters are commonSYNCHRONOUS TRANSMISSION
ASYNCHRONOUS TRANSMISSION
SYNCHRONOUS TRANSMISSION
ASYNCHRONOUS TRANSMISSION
Meaning Sends
data in the form of blocks or frames
Sends 1 byte or character
at a time
Transmission Speed Fast Slow
Cost Expensive Economical
Time
Interval Constant Random
Gap between the data Absent Present
AJAX technique uses the data-pull mode,
and supports both synchronous and asynchronous modes by API. Through
experiments we have noted that the DC technique implemented by AJAX is the
simplest form of the DC. Furthermore, the underlying concept used to implement
the AJAX technique can be developed in other environments –
Like desktop applications – using other
TTs like WS or C#, even without JS and/or XHR object. We have successfully
developed and tested the technique using C#.Net, to develop
a desktop application component, which
communicates with server components using data- pull DC, asynchronously.
Moreover, the same DC technique is utilized in other
Advanced DC technologies like WS, for the data-pull mode. To denote the
abstract concept
of this simplest implementation of the DC model, we
propose the term “Simple Pull Delta-Communication” (SPDC). Since the
SPCD concept is abstract, it is TTs
independent and can be developed for both browser-based
and
non-browser-based clients.
One of JavaScript’s greatest strengths is its ability to make asynchronous
requests. AJAX. Microsoft invented Ajax in 1999.AJAX
can be seen as the beginning of the JS based RIA development approach, and it
became a major breakthrough in the web development area (Salva & Laurencot, 2009). After its introduction, developers were learning how to use AJAX
to create desktop-like GUIs in the web applications such as Google Maps; and
later they subsequently used AJAX even to create entire
enterprise RIAs (Lawton,
2008). Using the JS’s ability to manipulate the Document
Object Model (DOM) in HTML documents, AJAX achieves and enhances the
interoperability capability of the web applications (Salva & Laurencot, 2009).
It should be noted that the AJAX itself is not a technology, it is a technique;
and the technology behind AJAX is the XHR object with its JS API. The AJAX is a data-pull technique, employing the
traditional request-response model. Combining HTML and CSS with JS, AJAX has
become a powerful tool in RIA development, providing the fundamental
implementation of the DC.
Google made a wide deployment of standards-compliant, cross browser Ajax
with Gmail (2004) and Google Maps (2005). In October 2004 Kayak.com's public
beta release was among
the first large-scale e-commerce uses of what their developers at that time called "the xml http
thing".[10] This increased interest in AJAX among web
program developers.
The term Ajax was publicly used on 18 February
2005 by Jesse James Garrett in an article titled Ajax: A New Approach to Web Applications, based on techniques used
on Google pages.
XHR is also known as
XMLHttpRequest. The XMLHttpRequest object was
initially defined as part of the WHATWG’s
HTML effort. (Based on Microsoft’s implementation many years prior.)
It moved to the W3C in 2006. Extensions (e.g. progress events and
cross-origin requests) to XMLHttpRequest were
developed in a separate draft (XMLHttpRequest Level 2) until end of 2011, at which point the two drafts were merged and XMLHttpRequest became
a single entity again from a standards perspective. End of 2012 it moved back to the WHATWG.On
Chrome or other browsers, if you were to inspect any page, you could head over
to the Network tab, then notice a sub-tab called XHR. Within
this tab, you could see the status of requests, how long requests take, and
plenty more. Microsoft was working on a technology named XMLHTTP in
their Exchange 2000 project [18], and it was first introduced to the world as
an ActiveX control in Internet Explorer 5.0 in March 1999 [19], [20]; and later
it was called the XMLHttpRequest (XHR) object, which has an Application
Programmer Interface (API) in JS. The XMLHttpRequest object can be used to
request data from a web server.
The XMLHttpRequest object is a developers dream, because you can:
Update a web page without reloading the page
Request data from a server - after the page has loaded
Receive data from a server - after the page has loaded Send data to a server - in the background
Simple Pull Delta-
Communication is the basic abstract of
Delta-Communication technique, based on the data-pull mode. It describes the
simplest form of data-pull Delta- Communication, based on the request-response
model and this technique is technology independent.
AJAX technique as a
JS implementation of the SPDC, which is limited to the browser based
applications. XHR object has the ability to develop the rich communication not
only in asynchronous mode, but also in synchronous mode, since the XHR API
contains a setting to configure the synchronous/asynchronous mode. However, even using the asynchronous setting of the XHR object,
still AJAX features
can be developed and presented to the users
to perform DC in synchronous
manner, and the mode of the DC is determined by the way the feature is
designed.
In later rich communication development
technologies like WS, a similar setting is not included, and the developers are
given the flexibility to determine, in which mode the DC should be developed. Based on these facts, considering the outdated and limited impression of the term “AJAX”,
we propose the term (JS-SPCD), in place of the term “AJAX”. The term JS- SPCS
indicates that it utilizes the SPDC technique, and developed using JS.
When the RIA bus is used all the AJAX
requests are directed to a dedicated file, which is assigned for the RIA Bus. As the system grows,
the developers can maintain separate
files for multiple RIA-buses
for different modules.
Then the JavaScript in AJAX engine
has to use the direct URLs
for these dedicated RIA bus files. There are two drawbacks here 1-there will be
multiple URLs to maintain, 2- the physical addresses of these files are exposed
to anyone which is not a good
practice. Using a small PHP code snippet in the index file the data in the
parameter segments can be extracted. According to the first URL parameter the module can be
identified and the
Writing regular AJAX code can be a bit tricky, because different browsers have
different syntax for AJAX implementation. This means that you will have to write extra code to test for different browsers. However, the
jQuery team has taken care of this for us, so that we can write AJAX
functionality with only one single line of
code.
jQuery
AJAX Methods
jQuery - AJAX load () Method
jQuery load () Method
The jQuery load () method
is a simple, but powerful AJAX method.
The load () method loads data
from a server and puts the returned data into the selected element.
Syntax:
$(selector).load (URL, data,
callback);
The required URL parameter specifies the URL you wish to
load.
The optional data
parameter specifies a set of query string key/value pairs to send along with
the request.
The optional
callback parameter is the name of a function to be executed after the load () method is completed.
Here is the content of our example file:
"demo_test.txt":
<h2>jQuery and AJAX is FUN!!!</h2>
<p
id="p1">This is some text in a paragraph.</p>
The following
example loads the content of the
file "demo_test.txt" into
a specific <div> element:
Example
$("#div1").load ("demo_test.txt");
It is also possible to add a jQuery selector to the URL
parameter.
The following
example loads the content of the element with id="p1", inside the
file "demo_test.txt", into a specific <div> element:
Example
$("#div1").load ("demo_test.txt
#p1")
The optional callback parameter specifies a
callback function to run when the load () method
is completed. The callback function can have different parameters:
responseTxt - contains the resulting content
if the call succeeds statusTxt - contains the status of the callxhr - contains the
XMLHttpRequest object
The following example displays an alert
box after the load () method completes. If the load
() method has succeeded, it displays "External content loaded
successfully!", and if it fails it displays an error message:
Example
$("button").click(function(){
$("#div1").load("demo_test.txt", function(responseTxt, statusTxt, xhr){ if(statusTxt == "success")
alert("External
content loaded successfully!"); if(statusTxt
== "error")
alert("Error: " + xhr.status
+ ": " + xhr.statusText);
});
});
AJAX is the art of exchanging data with a server,
and update parts of a web page - without reloading the whole page. The
following two are the jQuery AJAX methods:
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