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Asymetric behaviour in method call.

Posted on 2013-01-07
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Last Modified: 2013-01-08
The client makes a method call, which returns fine, with the data (object), and the programme runs. The pre-method call status is supposed to be restored when its business is finished, so that a different client can run the same routine. This time, the method appears to return an empty object, and I can't see why. The clients establish a direct UDP connection with each other via a primary TCP association. It's this TCP linkup routine that is failing. Anyone want to try to help throw some light on what may be happening? Thanks.
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Question by:krakatoa
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4 Comments
 
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dpearson earned 2000 total points
ID: 38753704
I don't think you should expect a general solution for this - you need to post some of the details of the method that is being called so we can try to figure out why it's returning an empty object.  

There's lots of possible reasons (bugs) that can cause this sort of thing...
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by:krakatoa
ID: 38753833
You are quite right Doug. Ironically, that's why I didn't post any code - there's too much, but I thought it was worth a stab asking generally, as after all I didn't have another clue. But I'm going to take a look at one particular area right now, and if that produces nothing, I'll get back with smthg here.
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by:krakatoa
ID: 38754462
It's a mystery to say the least. A client speaks to its server instance to fetch an object. It returns ok. That client can do that operation as often as. But (in say just a 2-client scenario) the other client, when it tries to do the same thing, receives an empty object. The clients are on separate machines, and each has a one-to-one with its server instance.

In the server instance, I've put in a line to print to screen the particular client's credentials. These get printed, therefore a call from either client is at least getting this far. This is the code in the server instance :

protocol = BR_voxinitreader.readLine().trim();
						
						
						if ("RNG".equals(protocol)) {

							try {
							iamcaller = true;
							oos.flush();
							
							System.out.println(myclientsInetAddress);
							oos.writeObject(PersephonepS.phoneDirectory);
			
							} catch (Exception exceptsock) {exceptsock.printStackTrace();}

						} 

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And this is the code in a calling client, asking for the object :

protected ConcurrentHashMap getPhoneDirectory(){ //remote class

				Object ob =null;
				      
				       try{

				       PW_voxiniwriter.println("RNG");
				       PW_voxiniwriter.flush();
				       ob=ois.readObject();

				       }catch(Exception oosex){}	

				       return((ConcurrentHashMap)ob);
			}

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LVL 16

Author Comment

by:krakatoa
ID: 38756874
You helped me think again about where the problem must be, since there is nothing wrong with the code, as I'm sure you know. ;) So your 'no comment' did the trick. I was erasing the object payload too early. It's fixed now.

But I'll be back with a couple of toughie questions again soon. ;)
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