Share My Creation Simple Multi-User Chat Demo

Sooner or later somebody will want to know how to do this. It seems to be a fairly common "What next after Hello World?" sort of project.

The attached ZIP archive has two B4J programs: SimpleServer and SimpleClient.

While there is a huge amount I have to learn yet about B4J, these seem to be working properly. That doesn't mean they're bug-free or that I haven't done some things clumsily but these ought to be useful to help others get started with TCP sockets.

As provided these use ASCII for transmission with a CR message delimiter. You could easily change them to use UTF-8 and another delimiter or a length prefix instead.

There is a ReadMe.txt in the archive and I'll try to post a screenshot here.
 

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LucaMs

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Thank you, Dilettante (anche se io credo che potrei scrivere "Grazie" :))

I need example like this (I have not downloaded it yet but I'm going to do it).

If you could convert it for BlueTooth and for PC to Android-device, I would avoid many headaches :p

Ciao e grazie


P.S. Sorry, Bob, "dilettante" is an italian word! lol
 
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dilettante

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It should be easy enough to convert SimpleClient into an Android version that interoperates with my Java SimpleServer using TCP sockets. Probably a little more work but not a lot to convert SimpleServer to an Android version.

To operate over Bluetooth the simplest thing might be to use a library containing a Java implementation of BluetoothSocket and BluetoothServerSocket, but I don't know whether such a library exists (either for Java itself or a even wrapped version for B4J to use). Android already has a Bluetooth Library that contains such classes, though I have not used it.

But I believe the custom here would be to create a question thread in order to get help with changes like this. It would probably bring in more people with specific experience using Bluetooth between an Android device and a Java device (such as a PC).
 
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dilettante

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Thanks Erel.

That wouldn't really be multiuser (COM-port per Android device/user might work) but it probably addresses the needs of many people. The use of sockets is probably constrained by platform limitations, since I haven't found anything like the Android Bluetooth library for Java on Windows or Linux.
 

LucaMs

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Yes, but I'd just need a conversation between pc and smartphone (without VB.Net or other!
Why I did not searched???

Thank you, Erel, this was for me the Christmas gift.

Thanks for your help, dilettante.

And again, happy holidays
 

BPak

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Love the Chat Project, dilettante. Ran great on my Mac as well. Only thing I had to do is put a Client.jar in another location to get the second Client working.
 

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jmon

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Hi,
Thanks a lot for sharing with us. I have an issue, the server constantly drops the connection and I keep on getting the "#Server closed connection" message on the client side. Any idea what could cause this issue?

Thanks.
 

dilettante

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Hi,
Thanks a lot for sharing with us. I have an issue, the server constantly drops the connection and I keep on getting the "#Server closed connection" message on the client side. Any idea what could cause this issue?

I haven't seen this. Are you using an unreliable WiFi or cellular data network or something? This is one of the reasons why HTTP 1.0 often works best for mobile clients: request, response, abandon the connection.

15 minutes (and counting), no drop-outs yet here.
 
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jmon

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I haven't seen this. Are you using an unreliable WiFi or cellular data network or something? This is one of the reasons why HTTP 1.0 often works best for mobile clients: request, response, abandon the connection.

15 minutes (and counting), no drop-outs yet here.
Thanks for your reply. I am on a LAN network. I will check if something else could be dropping the connection. I'll post again if I find something.

[EDIT] I apologize, your example works perfectly and doesn't drop the connection. I made a mistake when I modified your example in the "srvListener_NewConnection". I was setting the "intClient" to a wrong number and when new users where joining the conversation, they would be assigned to a wrong number and overlapping the old users, thus dropping the connection.
My bad!
 
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dilettante

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Love the Chat Project, dilettante. Ran great on my Mac as well. Only thing I had to do is put a Client.jar in another location to get the second Client working.

I'm still curious about this. On a Mac does the JAR file get locked so you can't run a second instance, or did I misinterpret the issue?
 

BPak

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Not a Mac specialist but it just would not run a second Client from same location. Guess it stops it from running second instance.

However, when copying the prog to another folder it was allowed to run a second program of the same name.

I could test it more if required.?
 

BPak

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I tested it again on Mac Lion and it will only run one instance.

However Right-click the Icon for the Client and select Copy from popup menu and a copy of the client is created. It can be ran and used as the second instance.
I also tried using Right-Click and selecting Duplicate which did same as Copy.

Did search from Spotlight for 'run another instance of an application' and came up with a Web Search for Google and found a couple web sites that confirm the Mac is ONE instance only by design.

https://www.google.com/search?rls=en_AU&q=run+another+instance+of+an+application&ie=UTF-8&oe=UTF-8

http://reviews.cnet.com/8301-13727_...multiple-instances-of-an-application-in-os-x/

One says Copy as I have done. The other says it can be done from the Console
 

jmon

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Thanks for your great script. It works very well.

I sometimes have a bug that would crash the server. This fixes the bug:
B4X:
Public Sub Close()
    astmClient.Close
    sckClient.IsInitialized Then
    sckClient.Close
    sckClient = Null
    mInUse = False 'switching this line
    CallSub2(mParent, mEventName & "_Terminated", Me) 'and this line
End Sub
I think you have to put the mInUse = False before the callSub2, because when calling the _Terminated event in the main module would still have this client registered as inUse = true and that could cause and crash the server if trying to send data to this client.
 
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