Embedded Web Technology is the merging of Embedded Systems.

Embedded Web Technology is the merging of Embedded Systems with the World Wide Web. Embedded Web Technology' decreases the cost of developing and maintaining the user interface by allowing the user to interface to the embedded system through a web browser running on a standard personal computer.An embedded system is a computer that has been built to solve only a few very specific problems and is not easily changed. The word embedded means it is built into the system.

Embedded web technology:

Embedded Web Technology was developed for the Fluids and Combustion Facility (FCF_ of the International Space Station (ISS). FCF is being developed to perform investigations in combustion science and fluids physics in the microgravity environment of the ISS. One of the goals of the FCF is to be able to perform at least 10 investigations in each discipline per year for 10 to 15 years. In order to meet this goal, it is important for the software to be adaptable to changing requirements. One of the areas of concern is the user interface software that the ISS astronauts will use to operate the FCF. The challenge facing the FCF software engineers is that the laptop computer that the user interface software will operate on is suppliedby the ISS, not FCF. In the event that the ISS decides to upgrade the laptop computer, the FCF software team will be required to modify existing user interface code for a new environment while still developing new code for possibly the old laptop computer and also the new laptop computer. The FCF software engineers are also faced with the task of developing a system that would accommodate unknown experiments. This scenario can be extended to any system where the users, hardware and applications are unknown and the system is expected to have along life.

The FCF software engineers realized that the World Wide Web had already solved a similar problem. With the World Wide Web, a person uses a web browser to request a web page from a web server. In this scenario, the web server and the web browser interface is independent of the hardware and softwarebeing utilized at the other end of the interface.

Embedded technology has been around for a long time and its use has gradually expanded into the PC market. Speed, accuracy, reliability were the reasons why embedded technology entered computers. With an great market size of billions in the next coming years, the future is embedded. Embedded systems contain processors, software, input sensors and output actuators, which work as the controls of a device and are subject to constraints.

These Embedded systems may not have disk drives, keyboards, display devices and are typically restricted in terms of power, memory, GUIs and debugging interfaces.The central building blocks are microcontrollers, i.e. microprocessors integrated with memory units and specific peripherals for the observation and control of these embedded systems.On the other hand, Web technologies employ client-server models.

The embedded Web system works on the same principle as that traditional Web request-response systems. Web pages from the embedded system (server) are transmitted to the Web browser (client) , which implements the user interface (Presentation layer). In other cases , the the embedded system dynamically generates the pages to convey the current state of the device to the user at the centralized location. These end users can also use the Web browser to send the information to the embedded system for the configuration and control ofd the device.

Web-enabled devices use the HTTP (Hyper Text Transfer Protocol) standard protocol to transmit Web pages from the embedded system to the Web browser , and to transmit HTML (Hyper Text Markup Languages) form the data from the browser back to the device. The devices require a network interface such as Ethernet ,TCP/IP software , embedded Web server software , and the Web pages (both static and generated) that make up the device- specific GUI.

The HTTP protocol engine takes the request from the Web browser and sends it on the TCP/IP. The HTTP protocol Engine parses the request and sends it to the embedded application for processing. After producing the results , the embedded application generates the HTML code and feeds it to the HTTP Engine , which sends it back to the client using TCP/IP.

Abstract of Embedded Web Technology

Embedded Web Technology (EWT) is regarded as the 'marriage' of Web technologies with embedded systems. In other words, the software developed for embedded systems is applied by making use of the Internet.

Introduction of Embedded Web Technology

Embedded Web Technology is an enabling, or platform, technology. This means that it is relevant to a wide variety of applications, many of which have not yet been identified. We at NASA have promoted EWT through workshops, participation in shows, and one-to-one consultations with our partners.

Embedded Software :

The Internet is the dominant method of information access. People are using universal clients such as Web browsers and email readers to connect to any system, from anywhere, and at any time.

With the use of embedded Internet technology, innovative companies are building products that let people use these same universal clients to manage embedded devices. Using Web or email technologies in a networked device delivers user control with any Web browser or email client. This approach eliminates the need to build custom management applications and provides access to the device using the Internet tools that everyone is familiar with.

Embedded software space is vast and wide open. Newer embedded systems can require different software based applications.

These software based applications are :

Database applications,
Internet applications,
Mobile office productivity tools,
And personal applications.

Developing and running these applications require tools and supporting software platforms. All these embedded software requirements can be broadly classified into "embedded database", "embedded language extensions", "embedded development tools", "embedded applications" and their sub-classification will be a long list of specific areas.

COMPARISON OF A TYPICAL WEB SERVER ENVIRONMENT VERSUS AN EMBEDDED, REAL-TIME ENVIRONMENT

A typical web server runs on a computer that is running a nonrealtime operating system. The web server software itself tends to be large and complex and requires a lot of memory and dist, space, on the order of 10 MB or more. The web servers are designed to run on personal computers and general purpose workstations.

The embedded, real-time environment is much more restricted. The system generally consists of an embedded processor running a real-time operating system and also running a real-time application. Embedded systems have limit_'d memory and disk space that is not easily extensible The users of these two environments have different needs of the systems. The user of the nom'ealtime environment is usually interested in obtaining static or slowly changing information. This information is stored in files and retrieved by the web browser for display by the user. The user can read the information on the display at his own pace or pnnt it out and read it without the aid of the browser. A user of a real-time system, on the other hand, is interested in obtaining the most current data from the system at regular intervals. The user may require the capability to issue commands to the embedded system.

PUTTING EMBEDDED SYSIEMS ON THE WEB

There are two problems thai need to be solved in order for an embedded system to become accessible on the World Wide Web. One is providing a user interface that provides the real-time interaction needed by the user in order to properly interface to the system. The other is to give the embedded system the capability to serve web pages over the World Wide Web.

One feature of the web browser that helped bridge the gap between the two environments is the addition ofJava TM applets. Applets are programs that are capable of being executed by a web browser. They are written in the Java TM language, compiled and then stored on the web server's computer. When a web page is transmitted to a web browser, the web browser scans through the web page, looking for, among other things, applet tags.

When an applet tag is found, the web browser automalically makes another request to the web server for the applet. The applet gets sent to the web browser which in turn loads the Java TM Virtual Machine which starts running the applet. In the typical web environment, applets provide an interface that is dynamic but usually does not interact with the web server's computer. For security purposes, applets are very restricted in what the3' can do in a web browser environment. It is possible to bypass these restrictions with security certificates if they are an impedirnent.

One capability an applet has by default is the ability to communicate back to the computer that served it to the web browser. This comnmnication can be accomplished with basic socket technology, Java's TM Remote Method Invocation (RMI), Common Object Request Broker Architecture technology, or other protocols. RMI is a communication technology specific to Java TM that allows networked Java TM programs to interface in a platform independent manner developed by the Object Management GroupTSL is a technology that allows networked programs to communicate in a common manner that is independent of the underlying hardware, operating system or language. With this capability, it is possible to develop an applet that can interact dynamically with an embedded, real-time system and, thus, let the web browser provide a user interface that meets the needs of the user. On the embedded system side, the problem is providing the capability to be a web server without overburdening the system with all of the functionality specified in the HTTP specification. The embedded system software still needs to be able to perform realtime command and control. This problem was solved by the development of Tempest.

EWT is the marriage of embedded systems and the World Wide Web. Embedded systems, in contrast to general purpose computers such as a desktop, contain processors, software, input sensors and output actuators all of which are dedicated to the control of a specific device.

EWT was developed during the late summer by members of NASA Lewis Research Center, Flight Software Engineering Branch of the Engineering Design and Analysis Division of the Engineering and Technical Services Directorate.  It was modified in 2002.

What is Embedded Technology ?

Embedded technology is software or hardware that is hidden—embedded—in a large device or system.It typically refers to a fixed function device, as compared with a PC, which runs general-purpose applications.  An early example of embedded technology is the engine control unit in a car, which measures what settings to give the engine.

INTRODUCTION TO THE EMBEDDED WEB SERVER

 Embedded Web Server Technology is most evolving technology for Internet Devices.

 There are many application areas including internet devices, telecommunication devices, measuring instruments and lots of consumer electronics.

 Emerging Web technologies for embedded applications  Design Issues for Embedded Web Servers Traditional Web servers are designed to serve static Web pages from high-end workstations with plentiful CPU and memory resources. Embedded Web servers have different requirements for which traditional technologies are unsuitable.  Protocol Considerations  Embedded Software Considerations

There are two primary actors when communicating over the web, the server and the client. For right now think of the server and the client as two desktop computers.

 The server computer waits for the client computer to initiate communication and then the client computer makes a request for information.

 If the server computer understands the request it replies with a response.

 If the server computer does not understand the request it replies back to the client computer with an error. This pattern is called the client-server.

Client-server model between two computers

 To transfer information in this request-response manner both the web service and the web browser must talk the same language. That language is called Hypertext Transfer Protocol or HTTP. HTTP is built on other standard protocols such as TCP/IP.

HOW THE WEB WORKS

 The server boots up, when it is ready to starts the web service program.

 A user on the client machine opens up a web browser. At this point both the web browser and the web service are running and idle.

The client types in a URL in the address bar, which is related to the location of the server, such as http://www.ni.com.

 The server sees the request and replies back in HTTP with some type of content, like a picture of a cat.

The client receives the response and since it is a web browser it renders the cat picture so that the client sees a picture of a cat.

The embedded Web system works on the same principle as that traditional Web request-response systems.

Web pages from the embedded system (server) are transmitted to the Web browser (client) , which implements the user interface (Presentation layer).

 Web-enabled devices use the HTTP (Hyper Text Transfer Protocol) standard protocol to transmit Web pages from the embedded system to the Web browser , and to transmit HTML (Hyper Text Markup Languages) form the data from the browser back to the device.

 The HTTP protocol engine takes the request from the Web browser and sends it on the TCP/IP. The HTTP protocol Engine parses the request and sends it to the embedded application for processing.

 After producing the results , the embedded application generates the HTML code and feeds it to the HTTP Engine , which sends it back to the client using TCP/IP.

What is XML ?

 Extensible markup language (XML) is a structure for text so that information can be easily stored and transmitted through a web service. Although the L in XML stands for language , but it is not a programming language. XML is a popular content choice because it is human readable, and translates easily to other programming languages.

What is HTML?

 Hypertext markup language (HTML) is a language used to describe a webpage.

When a web browser receives content that is HTML it will try to render the content into a web page. Similar to XML, HTML is made up of tags, but unlike XML, HTML defines what types of tags are acceptable.

APPLICATIONS OF EWT

Space Communication

Biotechnology

Technology transfer and protocol

Education

Web technology in embedded applications has distinct advantages over legacy and custom communication mechanisms due to the ubiquity, scalability and security. The amount of knowledge and skills needed to create a web application may be large. Hopefully this article helps the understanding of basic concepts and how they apply to embedded applications. Once all the pieces are integrated with each other, the application becomes a functioning Web server that can be accessed via serial or Ethernet connection. Using this New drivers were also developed to interface the Net186 board to the parallel port cable of the camera and to the serial port of the servo control.

Advantages of embedded we technology:

The embedded system is easy for mass production.
The embedded system is highly reliable.
It has very few interconnections.
The embedded system is small in size.
The embedded system has less expensive.
It has fast operation.
It has improved product quality.
It optimizes use of system resources.
It has low power operation.

Disadvantages of embedded web technology:

The embedded systems are hard for maintenance as it is use and throw device.
It has no technological improvement.
Less power supply durability if it is battery operated.
It has hard to take backup of embedded files.