For example someone could write a java program to

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Unformatted text preview: pic. Java-enabled Browsers A conventional graphical browser works as follows (see Figure 18.3): 1. The user of the web-client calls on hypertext link. 2. The browser of the web-client computer decodes the URL address of the link. 3. The browser contacts the server corresponding to the URL address and requests for the object referenced by the link. 4. The server then fetches an object from the local computer and returns to the browser a bag of bytes that contains the object. 5. The browser then inspects the bytes to determine the type of the data such as HTML document or JPEG image, etc. 6. Finally, the browser uses the data type information to invoke the appropriate code to manipulate and display the object on the web-client computer's screen. Browser - User clicks on a hypertext link Browser - Browser decodes URL address of the link Browser - Browser requests corresponding object from the server Browser - Browser inspects the bytes to determine the type of the data Browser uses the data type information to invoke the appropriate code to manipulate and display the object on the computer's screen Network - request Network - Reply Server - Server fetches the object and returns to the browser a bag of bytes that contains the object Conventional graphical browsers that work in the manner described above are called "first-generation" browsers. The main problem with these browsers is that they are built in a monolithic fashion. That is, every possible type of data, protocol and behavior that a browser can deal with is frozen into its design when the browser is built. This means that every time a new data type, protocol, or behavior is invented, this browser must be upgraded to make it capable of dealing with the new situation. From the viewpoint of end users this is a difficult job because users must continually be aware of what data types and protocols exist, which browsers deal with which of these data types and protocols, and which versions of which browsers ar...
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This document was uploaded on 04/07/2014.

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