Re: [jgroups-dev] jgroups port to android

Awesome!!!

Yann, can you blog about it/write a summary?

Regards,
Vladimir

On 11-01-11 4:19 AM, Bela Ban wrote:
> Hi Yann,
>
> (don't forget to post to jg-dev...)
>
> Inline
>
> On 1/10/11 9:38 PM, Yann Sionneau wrote:
>> Hello,
>>
>> Good news ! It's working on android 2.1 2.2 and 2.3 !
>
> Great !
>
>
>> I have tested the SimpleChat application with 3 phones connected
>> together (1 HTC Desire on 2.3, 1 Nexus One on 2.2 and 1 HTC Hero on 2.1)
>> with 2 computers (1 Mac OS X Snow Leopard and 1 Ubuntu).
>>
>> All of these devices were connected to the same wifi subnetwork.
>> I used your Broadcast PING which did a good job !
>> my udp.xml conf : http://pastebin.com/HnNfukxa
>>
>> It was working just fine :)
>
> I see you used the default broadcast address of 255.255.255.255 without
> issues, good...
>
>
>> I ported the Draw demo from jgroups to android too (with several
>> modifications so that it's not compatible anymore with the PC version
>> included in your git repository).
>> It worked well with the phones :)
>
> Do you think there's a chance we can merge those changes back into the
> regular Draw, so we have 1 version. Or is this too cumbersome ?
>
>
>> Just one strange thing, if I draw on one phone, then start the app on a
>> second phone, the second phone does not get the history of the drawing,
>> it starts all blank. Is it normal ?
> Yes. By default, Draw doesn't do any state transfer (state == content of
> the canvas). If you start Draw with -state, it'll transfer the canvas.
>
>
>> With SimpleChat all the history was transmitted when joining the group.
>
> Yes, because SimpleChat by default uses state transfer.
>
>
>> Another question, I had troubles with this file :
>> src/org/jgroups/stack/RangeBasedRetransmitter.java , I modified it like
>> this :
>> https://github.com/fallen/JGroups/commit/959608be03f9e050fce2527e408f555062e4ab81
>
> I made a comment: this is a bug, as the keys (= execution times) will
> need to be ordered. So you could use TreeMap, but would then have to
> synchronize access to it, as TreeMap is not synchronized.
>
> The better solution (for now) is to use DefaultRetransmitter wherever
> RangeBasedRetransmitter is used. I had a configuration switch, but
> removed it some months ago because RangeBasedRetransmitter works really
> well.
>
> This is used by UNICAST2 and NAKACK, via NakReceiverWindow.
>
>
>> So I replaced the ConcurrentSkipListMap by a ConcurrentHashMap, because
>> ConcurrentSkipListMap is not available in Android 2.1 and 2.2 (it's only
>> available since 2.3 !)
>
> See my comment above
>
>
>> It seems to be working just fine, but in theory i am loosing the ordering in the HashMap, is this a serious issue ?
>
> Yes, it is
>
>
>> Or am I fine like
>> that ? Am I going to be in trouble later with bigger programs ?
>
> The exceution times are off, so when you run into retransmissions, they
> might get executed at an incorrect time (= too late).
>
>
>> I do not understand fully the possible side effects of this change !
>>
>> Thank you again for all your help, you have been more than helpful :)
>
> No problem. Let me know when the application is available, I'd like to
> try it out !
>
>


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