There is a wide range of web-based applications, which use a rich communication model such as Rich Internet Applications, mobile apps, cloud-based systems, Internet of Things based systems, etc.; however, a proper term to address them all and a definition, which covers and explains the common characteristics of them are missing. A definition of a concept is important as the definition provides a precise common understanding of the focused artifacts, which helps in increasing the realization of these artifacts towards proper utilization of them. We propose the umbrella term Rich Web-based Application to address the aforementioned types of applications, and also propose a definition for it, aligning to the common architectural characteristics of these applications. In addition, we deliver a set of taxonomies to classify the techniques and technologies related to the development of Rich Web-based Applications, in the direction of improving the understanding of the proper utilization of them. In future, we expect to introduce an architectural style for these Rich Web-based Applications, based on the proposed definition.
RIA Characteristics
Direct interaction: In a traditional page-based Web application, interaction is limited to a small group of standard controls: checkboxes, radio buttons and form fields. This severely hampers the creation of usable and engaging applications. An RIA can use a wider range of controls that allow greater efficiency and enhance the user experience. In RIAs, for example, users can interact directly with page elements through editing or drag-and-drop tools. They can also do things like pan across a map or other image.
Partial-page updating: Standard HTML-based Web pages are loaded once. If you update something on a page, the change must be sent back to the server, which makes the changes and then resends the entire page. There’s no other way to do it with HTTP and HTML. With traditional Web-based apps, network connectivity issues, processing limitations and other problems require users to wait while the entire page reloads. Even with broadband connections, wait times can be long and disruptive.But RIAs incorporate additional technologies, such as real-time streaming, high-performance client-side virtual machines, and local caching mechanisms that reduce latency (wait times) and increase responsiveness. A number of commercial development tools (see below) permit this partial-page updating.
Better feedback: Because of their ability to change parts of pages without reloading, RIAs can provide the user with fast and accurate feedback, real-time confirmation of actions and choices, and informative and detailed error messages
Consistency of look and feel: With RIA tools, the user interface and experience with different browsers and operating systems can be more carefully controlled and made consistent.
Offline use: When connectivity is unavailable, it might still be possible to use an RIA if the app is designed to retain its state locally on the client machine. (Developments in Web standards have also made it possible for some traditional Web applications to do that.)
Performance impact: epending on the application and network characteristics, RIAs can often perform better than traditional apps. In particular, applications that avoid round trips to the server by processing locally on the client are likely to be noticeably faster. Offloading such processing to the client machines can also improve server performance. The downside is that small, embedded and mobile devices — which are increasingly common — may not have the resources necessary to use such apps.
DELTA-COMMUNICATIONTECHNOLOGIES
Simple-Pull-Delta-Communication (SPDC) can be seen as the simplest form of DC
- Used in AJAX
- Single XHR request to the server
- Server-side: special technology is not needed
Polling is used to simulate data-push
- Send XHR requests periodically to the server
- Client-side: Native JS support
- Server-side: special technology is not needed
Comet is used to simulate data-push
- Long-lived XHR requests
- Client-side: Native JS support
- Server-side: Need a streaming server. Special technology is not needed, can be implemented with standard web technologies
- Blank responses are eliminated
WebSocket (WS) is bi-directional
- Supports both data-pull and true data-push
- Client-side: HTML5 provides native JS support
- Reduce network traffic than polling/Comet/SSE(highly scalable, 10CK is addressed)
Delta Communication
Web applications have evolved into much complex Rich Internet Applications, providing rich features and enhanced user experience. Proper definitions, which deliver abstract realization of the fundamental concepts of the Rich Internet Application are still missing. Definitions provide proper understanding of the subject and help in increasing the realization of the characteristics of the same. This paper focuses on conceptually identifying the characteristics of the rich communication model of the Rich Internet Applications – commonly known as the “Asynchronous Communication” – suggesting a better term “Delta-Communication”, followed by a definition for it. Based on the definition, we propose a term and a definition for the abstract model of the simplest rich communication technique, which is exploited in AJAX. Additionally, based on the proposed definition for the rich communication model, the paper proposes a new term to replace the term AJAX to overcome the limitations expressed by the term AJAX. These terms and definitions specify and express the fundamental characteristics of the abstract concepts of the rich communication model of the Rich Internet Applications. Index Terms—AJAX, asynchronous, communication, delta, rich internet applications.
AJAX : Asynchronous JavaScript And XML
AJAX stands for Asynchronous JavaScript And XML. AJAX is not a new technology but it is a technique. It is a term that is firstly penned by James Garrett in 2005. Basically, It is a way of using many existing technologies like HTML, CSS, JavaScript, XML, Document Object Model, and main important part is XMLHttpRequest object. When all these technologies work together with AJAX technique, User Interface updates itself without reloading the whole web page. Basically, AJAX will communicate with the server, get data from the server, update UI on the basis of that data without reloading the whole web page.
History of AJAX
Before 2005, communication between client-side and server-side was harder to establish. Developers use hidden iframes to populate the server data to the client-side. But in 2005, James Garrett write an article named AJAX: a new approach to Web applications. The key technology is used in AJAX is XMLHttpRequest(XHR), firstly invented by Microsoft and then use by other browsers. XHR has capabilities to retrieve data from server-side and populate on client-side with the help of existing technologies. Before 2005, developers use different technologies for communication with server-side such as Java Applets or Flash movies.
Delta-Communication can be seen as the power of Rich Internet Applications, and there are different Techniques and Technologies available for the development of Delta-Communication, which should be selected carefully into the Rich Internet Application development. Enough discussions are not available, which compare and contrast these Delta-Communication development Techniques and Technologies towards supporting decision making of selecting them. This paper provides an overview of the contemporary Techniques and Technologies available for the Delta-Communication development, contextually compares them aligning to some selected criteria, and finally discusses some facts to be considered when selecting them for the Rich Internet Application development. A literature survey on the Delta-Communication development Technologies and Techniques was conducted, which was followed by a series of experiments towards getting the empirical evidence for the comparison. During the contextual comparison, the Simple Pull Delta-Communication was identified as the least complex technique and the Websocket was noted as the highest complex technology.
Role of the DC-Bus
The DMCNET (Delta Motion Control Network) communication bus is a motion control communication protocol employing the high-speed bus developed by Delta; it employs different CRC code when engaging in two-way communications, has a transmission rate of 10Mbps in each channel, and supports a maximum communication distance of up to 30 m. Physical communication cables consist of CAT-5e STP Ethernet cable (24AWG/4Pairs).
HTTP
The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. This is the foundation for data communication for the World Wide Web (ie. internet) since 1990. HTTP is a generic and stateless protocol which can be used for other purposes as well using extension of its request methods, error codes and headers.
Ajax
Traditionally webpages required reloading to update their content. For web-based email this meant that users had to manually reload their inbox to check and see if they had new mail. This had huge drawbacks: it was slow and it required user input. When the user reloaded their inbox, the server had to reconstruct the entire web page and resend all of the HTML, CSS, JavaScript, as well as the user’s email. This was hugely inefficient. Ideally, the server should only have to send the user’s new messages, not the entire page. By 2003, all the major browsers solved this issue by adopting the XMLHttpRequest (XHR) object, allowing browsers to communicate with the server without requiring a page reload.The XMLHttpRequest object is part of a technology called Ajax (Asynchronous JavaScript and XML). Using Ajax, data could then be passed between the browser and the server, using the XMLHttpRequest API, without having to reload the web page. With the widespread adoption of the XMLHttpRequest object it quickly became possible to build web applications like Google Maps, and Gmail that used XMLHttpRequest to get new map tiles, or new email without having to reload the entire page.Ajax requests are triggered by JavaScript code; your code sendsUnfortunately, different browsers implement the Ajax API differently. Typically this meant that developers would have to account for all the different browsers to ensure that Ajax would work universally. Fortunately, jQuery provides Ajax support that abstracts away painful browser differences. It offers both a full-featured $.ajax() method, and simple convenience methods such as $.get(), $.getScript(), $.getJSON(), $.post(), and $().load().Most jQuery applications don’t in fact use XML, despite the name “Ajax”; instead, they transport data as plain HTML or JSON (JavaScript Object Notation).In general, Ajax does not work across domains. For instance, a webpage loaded from example1.com is unable to make an Ajax request to example2.com as it would violate the same origin policy. As a work around, JSONP (JSON with Padding) uses <script> tags to load files containing arbitrary JavaScript content and JSON, from another domain. More recently browsers have implemented a technology called Cross-Origin Resource Sharing (CORS), that allows Ajax requests to different domains
References:https://www.researchgate.net/publication/326395849_Rich_Web-based_Applications_An_Umbrella_Term_with_a_Definition_and_Taxonomies_for_Development_Techniques_and_Technologies
https://www.computerworld.com/article/2551058/rich-internet-applications.html
https://en.wikipedia.org/wiki/Comparison_of_synchronous_and_asynchronous_signalling
https://www.researchgate.net/publication/317383686_Delta_Communication_The_Power_of_the_Rich_Internet_Applications
Programming Applications 