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UDP Listener example?

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Eagle Offshore

UDP Listener example?

I'm trying to build a display for some instruments that multicast readings using UDP. I started out using CocoaAsyncSocket on Mac (https://github.com/robbiehanson/CocoaAsyncSocket) and I have to say it has a really wonderful api - would be worth cloning it.

However, want to do the same thing in Pharo so I have typed this little snippet into the workspace:

[| socket |
socket := Socket newUDP.
10 timesRepeat: [| s |
s := String new.
socket receiveDataInto: s fromHost: (NetNameResolver addressFromString:'255.255.255.255' ) port: 4848.
Transcript show: s.]] fork

and it doesn't seem to do anything.

What have I missed? Pharo 1.3 stable on SnowLeopard BTW.

Thanks,
-Todd Blanchard

jannik laval

Re: UDP Listener example?

Hi Todd,

The socket chapter in writing progress could help you: https://gforge.inria.fr/scm/viewvc.php/*checkout*/PharoByExampleTwo-Eng/Sockets/Sockets.pdf?root=pharobooks
I do not remember if the receiveData method is blocking. If not, you should wait til data arrives.

Cheers,
Jannik

On Feb 6, 2012, at 22:22 , Eagle Offshore wrote:

> I'm trying to build a display for some instruments that multicast readings using UDP. I started out using CocoaAsyncSocket on Mac (https://github.com/robbiehanson/CocoaAsyncSocket) and I have to say it has a really wonderful api - would be worth cloning it.
>
> However, want to do the same thing in Pharo so I have typed this little snippet into the workspace:
>
> [| socket |
> socket := Socket newUDP.
> 10 timesRepeat: [| s |
> s := String new.
> socket receiveDataInto: s fromHost: (NetNameResolver addressFromString:'255.255.255.255' ) port: 4848.
> Transcript show: s.]] fork
>
> and it doesn't seem to do anything.
>
> What have I missed? Pharo 1.3 stable on SnowLeopard BTW.
>
> Thanks,
> -Todd Blanchard
>

---
Jannik Laval

Sven Van Caekenberghe

Re: UDP Listener example?

In reply to this post by Eagle Offshore

Todd,

On 06 Feb 2012, at 22:22, Eagle Offshore wrote:

> [| socket |
> socket := Socket newUDP.
> 10 timesRepeat: [| s |
> s := String new.
> socket receiveDataInto: s fromHost: (NetNameResolver addressFromString:'255.255.255.255' ) port: 4848.
> Transcript show: s.]] fork
>
> and it doesn't seem to do anything.
>
> What have I missed?

It is a non-blocking API, so you have to write some code to keep on listening until some timeout, in a loop with small delays, like 50ms. Also, you have to preallocate a non-empty buffer.

I have some working code for this, but it is not clean/standalone enough to show here ;-)

If you can't figure it out yourself, just ask and I will mail some of it to you off list.

Regards,

Sven

Eagle Offshore

Re: UDP Listener example?

In reply to this post by jannik laval

Thanks, I found this but it pretty well ignores UDP other than mentioning it exists.

On Feb 6, 2012, at 1:38 PM, jannik.laval wrote:

> Hi Todd,
>
> The socket chapter in writing progress could help you: https://gforge.inria.fr/scm/viewvc.php/*checkout*/PharoByExampleTwo-Eng/Sockets/Sockets.pdf?root=pharobooks
> I do not remember if the receiveData method is blocking. If not, you should wait til data arrives.
>
> Cheers,
> Jannik
>
> On Feb 6, 2012, at 22:22 , Eagle Offshore wrote:
>
>> I'm trying to build a display for some instruments that multicast readings using UDP. I started out using CocoaAsyncSocket on Mac (https://github.com/robbiehanson/CocoaAsyncSocket) and I have to say it has a really wonderful api - would be worth cloning it.
>>
>> However, want to do the same thing in Pharo so I have typed this little snippet into the workspace:
>>
>> [| socket |
>> socket := Socket newUDP.
>> 10 timesRepeat: [| s |
>> s := String new.
>> socket receiveDataInto: s fromHost: (NetNameResolver addressFromString:'255.255.255.255' ) port: 4848.
>> Transcript show: s.]] fork
>>
>> and it doesn't seem to do anything.
>>
>> What have I missed? Pharo 1.3 stable on SnowLeopard BTW.
>>
>> Thanks,
>> -Todd Blanchard
>>
>
> ---
> Jannik Laval
>
>

NorbertHartl

Re: UDP Listener example?

Am 06.02.2012 um 23:13 schrieb Eagle Offshore:

> Thanks, I found this but it pretty well ignores UDP other than mentioning it exists.
>
I think you might confuse the host and port portions of it. If you use

socket receiveDataInto:fromHost:port:

then the host and the port are the ones of the sending side. You need to specify your own side as well

| localPort sourceAddress sourcePort buffer receivedBytes socket delay |
localPort := 5000.
sourceAddress := NetNameResolver addressFromString: '255.255.255.255'.
sourcePort := 4848.

buffer := ByteArray new: 1000.
delay := Delay forMilliseconds: 50.

socket := Socket newUDP setPort: localPort.
[[ receivedBytes := socket receiveDataInto: buffer fromHost: sourceAddress port: sourcePort.
receivedBytes isZero ] whileTrue: [ delay wait ]]
ensure: [ socket closeAndDestroy].

Or you are better off testing it by using #receiveDataInto: instead of #receiveDataInto:fromHost:port:

Norbert

>
> On Feb 6, 2012, at 1:38 PM, jannik.laval wrote:
>
>> Hi Todd,
>>
>> The socket chapter in writing progress could help you: https://gforge.inria.fr/scm/viewvc.php/*checkout*/PharoByExampleTwo-Eng/Sockets/Sockets.pdf?root=pharobooks
>> I do not remember if the receiveData method is blocking. If not, you should wait til data arrives.
>>
>> Cheers,
>> Jannik
>>
>> On Feb 6, 2012, at 22:22 , Eagle Offshore wrote:
>>
>>> I'm trying to build a display for some instruments that multicast readings using UDP. I started out using CocoaAsyncSocket on Mac (https://github.com/robbiehanson/CocoaAsyncSocket) and I have to say it has a really wonderful api - would be worth cloning it.
>>>
>>> However, want to do the same thing in Pharo so I have typed this little snippet into the workspace:
>>>
>>> [| socket |
>>> socket := Socket newUDP.
>>> 10 timesRepeat: [| s |
>>> s := String new.
>>> socket receiveDataInto: s fromHost: (NetNameResolver addressFromString:'255.255.255.255' ) port: 4848.
>>> Transcript show: s.]] fork
>>>
>>> and it doesn't seem to do anything.
>>>
>>> What have I missed? Pharo 1.3 stable on SnowLeopard BTW.
>>>
>>> Thanks,
>>> -Todd Blanchard
>>>
>>
>> ---
>> Jannik Laval
>>
>>
>
>