Re: Building a remote countdown clock

Herbert said

<<Some code:

Socket initializeNetwork  "Only once per image"
dst := Socket newUDP setPort: 1979.
src := Socket newUDP setPort: 2345.
buff := ByteArray new: 1026.
delay := Delay forMilliseconds: 10.
localhost := ByteArray withAll: { 192. 168. 42. 11 }.
received := nil.

rp := [[ received := dst receiveUDPDataInto: buff.
 received first  isZero ] whileTrue: [ delay wait ].
 WorldState addDeferredUIMessage: [ { buff. received } inspect ]] fork.

src sendUDPData: ( 'ctmame' , (String value: 10) , (String value: 162)) toHost: localhost port:  1979.

rp terminate.
src closeAndDestroy.
dst closeAndDestroy.

src := nil.
dst := nil.
buff := nil.
delay := nil.
rp := nil.

Smalltalk garbageCollect
Socket allInstances>>

That's great, thank you very much.  I have a couple of other questions that sprang from using this code.
1. I couldn't get the WorldState addDeferredUIMessage: to do anything.  What is supposed to happen?  I am running the latest Pharo build. The class exists, and I didn't get a DNU, but I didn't get anything else either!

2. Out of curiosity, I tried used the NetNameResolver addressForName: method as a way of getting a socket address  (instead of using the ByteArray.  I tried this when nothing was working, and I noticed the method call in several of the Socket methods.  However, Squeak gave me a DNU.  Is there a simple way to enter host names using the NetNameResolver, or have I completely misunderstood its function?

Cheers
Andy

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Hi Andy,

AB> That's great, thank you very much.  I have a couple of other
AB> questions that sprang from using this code.
AB> 1. I couldn't get the WorldState addDeferredUIMessage: to do
AB> anything.  What is supposed to happen?  I am running the latest
AB> Pharo build. The class exists, and I didn't get a DNU, but I
AB> didn't get anything else either!

uh yeah I wasn't sure what approach you would choose and I was about
to leave for work. Sorry.

First I'm on Squeak 3.8 so let me try Pharo.

All works fine in what I just downloaded from Pharo Website.

So, after you added the deferred UI message, the next line
(sendUDPData...) should pop up an Inspector with an Array. I found the
deferred UI message trick somewhere in the archives or maybe got
direct help from someone. You won't need it.

You need two images. In the receiver you build a loop in which you do
something like:

commSocket dataAvailable
  ifTrue: [receiveResult :=
   commSocket receiveUDPDataInto: receiveBuffer.
   "now display your time in a big TextMorph"]
  ifFalse: [myDelay wait]


Doing real time asynchronous things with the Squeak UI is a bit tricky
but following the lead of ClockMorph should get you going.

The common animation methods in Squeak isolate you from that problems
but changing a Morph's shape at the wrong moment is not good. Sorry I
can't be more specific but if you report problems I will remember
them, I did several animations of lots of Morphs.

AB> 2. Out of curiosity, I tried used the NetNameResolver
AB> addressForName: method as a way of getting a socket address 
AB> (instead of using the ByteArray.  I tried this when nothing was
AB> working, and I noticed the method call in several of the Socket
AB> methods.  However, Squeak gave me a DNU.  Is there a simple way to
AB> enter host names using the NetNameResolver, or have I completely
AB> misunderstood its function?

no, you haven't. I used the code in a network with fixed IP's and no
DHCP running. Right here using NetNameResolver works just fine. If you
doIt:

(NetNameResolver addressForName: 'aComputersName') inspect

you should get an Inspector on a ByteArray with the IP address.


Cheers,

Herbert  

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David Corking said <<

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Herbert said <<

no, you haven't. I used the code in a network with fixed IP's and no
DHCP running. Right here using NetNameResolver works just fine. If you
doIt:

(NetNameResolver addressForName: 'aComputersName') inspect

you should get an Inspector on a ByteArray with the IP address.
>>

Hmmm, I was expecting to get an inspector on a ByteArray, but what I actually got was an inspector on SocketAddress. Something is obviously not quite right here! :-)

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Hi Andy,

AB> (NetNameResolver addressForName: 'aComputersName') inspect

AB> you should get an Inspector on a ByteArray with the IP address.

AB> Hmmm, I was expecting to get an inspector on a ByteArray, but
AB> what I actually got was an inspector on SocketAddress. Something
AB> is obviously not quite right here! :-)

again not on your side, I tried in Pharo and they introduced a class
SocketAddress.

You have to send that instance the message hostNumber to get the
IP-Address as .... oops ... a String. I surely didn't expect that!

What makes it worse, is that my code works though I hand an Array
as the IP address to Socket. So my best guess is you go to the Pharo
list and ask about the proper way to set up a UDP (or TCP) connection.

I could tell you how to pick the bytes out of SocketAddress but this
is Smalltalk after all. There must be a high level way.

Sorry for no better reply,

Herbert  

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