Re: [Pyxida-users] Pyxida developer + help

[Eric Chan-T. <dch...@cs...>]

Thank you for the clarification.

I've been reading through your published papers and code and I must say I 
learned a lot about how Pyxida works :)

I still have a quick and easy (hopefully) question. Each Pyxida node has a 
small amount of neighbors and learn about other nodes through other nodes. 
I am running on about 200 machines, and it seems like all the Pyxida nodes 
are adding each other to their upNeighbors set. NCClient.java has the 
MAX_NEIGHBORS set to 512.

I wanted to make sure that I am not misreading the code, but shouldn't each 
Pyxida node keep a small number of neighbors in its upNeighbors set. Else, 
it will be a lot of updates to send a gossipMessage to all 200 neighbors, 
and it also means that a Pyxida node has the whole network in its 
upNeighbors set - that seems wrong. I am inclined to change the value of 
MAX_NEIGHBORS but wanted to make sure that my understanding is correct 
first.

Thank you,

Eric

On Mar 13 2008, Jonathan Ledlie wrote:

>
>Eric,
>
>IIRC, we set up two coordinate systems so we could experiment with  
>different algorithms for updating them in parallel.  In other words,  
>the same sets of latency measurements would be experienced at the same  
>time -- how do different algorithms respond to them.  You might well  
>find this functionality useful.  If you wanted to expand it to include  
>more than two, I'm sure this wouldn't be too tricky.
>
>So, both coordinates are for the same node, but different coordinate  
>systems.
>
>-jonathan
>
>On Mar 13, 2008, at 1:45 PM, Peter Pietzuch wrote:
>
>> Jonathan, can you shed some light into this?
>>
>> Cheers,
>>   Peter
>>
>> Eric Chan-Tin wrote:
>>> Thanks for the help.
>>>
>>> The problem was that I was using jdk 1.6 and even though I cleaned  
>>> and
>>> recompiled util-prp and ASync and copied the jar files to Pyxida/ 
>>> lib, it
>>> still failed with the same error message. But I downgraded to jdk  
>>> 1.5.0_09
>>> and seems to be working fine now. I assume that some of the jar  
>>> files in
>>> Pyxida/lib were compiled under jdk1.5.
>>>
>>> One more question though. Why are there "update1" and "update2"? More
>>> specifically, why would CoordClient have two NCClient - a primaryNC  
>>> and a
>>> secondaryNC?
>>>
>>> Let's say there are two Pyxida clients - A and B. In an update,  
>>> update1
>>> would refer to A and update2 would refer to B (B sends A a  
>>> message). Is
>>> that a correct interpretation?
>>>
>>> Thank you,
>>>
>>> Eric
>>>
>>> On Mar 11 2008, Peter Pietzuch wrote:
>>>
>>>> Dear Eric,
>>>>
>>>> Eric Chan-Tin wrote:
>>>>> I am interested in helping with the Pyxida project. I read a  
>>>>> couple of
>>>>> papers about how network coordinate systems (for example GNP or  
>>>>> Vivaldi)
>>>>> are insecure and wanted to implement some countermeasures against  
>>>>> those
>>>>> attacks. Instead of creating my own Vivaldi implementation, I  
>>>>> thought of
>>>>> just using Pyxida instead.
>>>> It's great to hear that you want to help out with the Pyxida  
>>>> project. Let
>>>> me know when you have code to contribute and I'll set you up with
>>>> developer access.
>>>>
>>>>> [quote] WA 1205186886103 NetUtil : Could not deserialize java  
>>>>> object:
>>>>> java.io.StreamCorruptedException: invalid type code: 80 WA  
>>>>> 1205186886103
>>>>> ObjComm$ReadConnHa: No valid msgObject received from
>>>>> remoteAddr=<address>:55504. Ignoring. [\quote]
>>>> Usually, deserialisation problems like this one indicate that  
>>>> class files
>>>> were compiled using different Java versions. Have you tried  
>>>> recompiling
>>>> everything from scratch using, say, Java 1.5? Make sure that you  
>>>> also
>>>> rebuild some of the helper libraries (i.e. prp-util).
>>>>
>>>> Let me know if you have any other questions.
>>>>
>>>> Cheers,
>>>>  Peter
>>
>>
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