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The bottom line is that with socket programming, it is easy to write code that will cause a stream of bytes to flow in both directions between a clientand a server. This is no more difficult than causing a stream of bytes to flow in both directions between memory and a file on a disk.

However, getting the bytes to flow is the easy part. Beyond that, you must do all of the programming to implement an application protocol that is understoodby both the client and the server.

URL Programming

URL programming occurs at a higher level than socket programming, and in theory represents a very powerful idea.

In theory, by using the URL class, you can open a connection to a resource on the web, specified by a URL object, and simply call the getContent method on that URL object. The content of the resource will then be magically downloaded and will appear as an object on the clientmachine, even if it requires an application protocol that didn't exist when you wrote the program, and contains content that you didn't understand when youwrote the program.

This description may be a bit of an overstatement, but it is pretty close to the claims being made. This is a powerful idea, which may or may not bear fruitin the future.

If fully implemented by browsers, the idea means that you can place new and unusual material on a web site along with special content handlers and protocolhandlers. Then a cooperating browser will use those special handlers to move that material from the web site to the client and interpret its content once itgets there without a requirement to install software (such as plug-ins) on the client computer on a permanent basis.

Here is what Peter van der Linden has to say about this topic in his excellent book titled Just Java 1.1 and Beyond:

"If a browser doesn't recognize a media type, it should be able to download the code to process it from the same place it got the file. If theyever get this working, it will be ... a good thing."

Is it working, or will they ever get it working? I don't know. If it depends on cooperation among all the major players, including the major browser vendors- probably not. Therefore, I don't plan to spend much time on the topic of protocol and content handlers until I see some evidence that it is working tosuch an extent that it is practically useful.

That is not to say that you couldn't use the capability right now if you were developing an intranet and wanted the clients to have access to new and unusualcontent. It would be necessary for you to provide the appropriate protocol and content handlers, and it would probably be necessary for the clients to run Javaapplications written by you instead of standard browsers to access the data.

Also, the URL class provides an alternative way to connect one computer to another and transfer data on a stream basis, so we will see someexamples of retrieving data from a server by obtaining a URL connection, and then opening and servicing I/O streams between the client and the server. Wewill see some sample programs that make use of this technique, but we will also see that it is somewhat redundant with the socket programming approach.

A local area network

This is part of a sub-collection of modules designed for teaching network programming. Therefore, you may find some of the modules more meaningful if youare able to connect two or more computers in a local area network and run the sample programs across the network.

However, it is possible to simulate a network inside a single computer. If you are unable to create an actual network, you should be able to run all of thesample programs by simulating a network in your single computer.

The operating system

While the capabilities of Java are generally independent of the operating system in use, the manner in which an individual computer must be configured fornetwork operation is generally not independent of the operating system.

In those cases where these modules provide instructions for configuring the computer, those instructions will assume a Windows operating system. If you areusing a different operating system, you will need to translate those instructions into your operating system.

What's Next?

We will learn how to use the Java InetAddress class to find the domain name corresponding to an IP address, and to find the IP addresscorresponding to a domain name in our sample program in the next module.

Miscellaneous

This section contains a variety of miscellaneous information.

Housekeeping material
  • Module name: Java4620: General Information
  • File: Java4620.htm
  • Published: 03/02/14
  • Revised 12/26/14
Disclaimers:

Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.

I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.

In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published without my prior knowledge.

Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.

-end-

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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