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explanation: Java app server

Posted on 2001-09-13
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BEA claims that Java Application servers must be written in 100% Java to ensure:

"..Complete support for all Java native features like passing objects by value, dynamic update of system and business programs..."

1, What's the advantage of the feature "passing objects by value?"
2, What's "dynamic update of system and business programs?" what does this mean?
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Question by:txholdem
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by:dorothy2
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I can tackle #1, and I can make a good guess about #2.

#1 - They are talking about passing object data by value as opposed to passing by reference.

If you pass by value, you make a copy of the object. You can then pass it to a method as an argument. Whatever happens inside the method does not change the value of the object which was passed. The advantage of pass by value is security, because the caller's object data does not change.

With pass by reference, the actual object instance reference is passed to the method. Now any change to the instance's variables inside the method will be reflected when the method is finished and control returns to the calling program. The advantage of pass by reference is performance, because the overhead required to create a new object is not required.

#2 - dynamic update of system and business programs - if an application uses java technologies such as servlets and java server pages, it is relatively easy to update the site and change the programs on the fly. Some app servers may require you to "reboot" the application, but this takes only a few minutes. Some app servers may be able to serve up modified servlets and jsps as they are changed without restarting the server. To accomplish this the application server must support technologies like servlets and jsps.

Dorothy

Dorothy




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by:dorothy2
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I can tackle #1, and I can make a good guess about #2.

#1 - They are talking about passing object data by value as opposed to passing by reference.

If you pass by value, you make a copy of the object. You can then pass it to a method as an argument. Whatever happens inside the method does not change the value of the object which was passed. The advantage of pass by value is security, because the caller's object data does not change.

With pass by reference, the actual object instance reference is passed to the method. Now any change to the instance's variables inside the method will be reflected when the method is finished and control returns to the calling program. The advantage of pass by reference is performance, because the overhead required to create a new object is not required.

#2 - dynamic update of system and business programs - if an application uses java technologies such as servlets and java server pages, it is relatively easy to update the site and change the programs on the fly. Some app servers may require you to "reboot" the application, but this takes only a few minutes. Some app servers may be able to serve up modified servlets and jsps as they are changed without restarting the server. To accomplish this the application server must support technologies like servlets and jsps.

Dorothy

Dorothy




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objects earned 30 total points
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Not sure what they're talking about because all Java variable are passed by value. It's a language feature and has nothing to do with whether they're 100% Java or not.
All Java programs including ones that are not 100% Java still pass all variable by value.
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by:objects
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Point 2 also sounds like marketing 'wind'.
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by:Venabili
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No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

- points for objects

Please leave any comments here within the next seven days.
 
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Venabili
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