[DUG] Indy Sockets - How to Receive Asynchronously

Thu Dec 4 10:07:23 NZDT 2008

Also, I have not looked at indy for a long time, but I think they have new
objects at a higher level called TCPCommand, which supports CRLF message
management with events.

On Thu, Dec 4, 2008 at 10:06 AM, Kyley Harris <kyleyharris at gmail.com> wrote:

> in that case, your TCP thread should just loop read everything into your
> own buffer and everytime you find CRLF you can grab the complete message
> from the buffer and trigger an event. to stop yourself getting lock timeouts
> on reads use the checkfordataonsource and then read whatever is in the input
> buffer, that way you wont ever get a long timeout waiting for data that
> might not come.
>
>
> On Thu, Dec 4, 2008 at 10:01 AM, Eric A <eaa603 at hotmail.com> wrote:
>
>>  Known factors:
>>
>> 1. I don't know what size message will be returned.
>>
>> 2. The message always ends in CR LF
>>
>> 3. The message is always printable ASCII (not Unicode).
>>
>>
>>
>>
>> ------------------------------
>>
>> Date: Thu, 4 Dec 2008 09:48:52 +1300
>>
>> From: kyleyharris at gmail.com
>> To: delphi at delphi.org.nz
>> Subject: Re: [DUG] Indy Sockets - How to Receive Asynchronously
>>
>> Also, I guess the type of data and your message layer has a big impact on
>> how you design your data receiver.
>>
>> in my own client/servers where I control the protocol, all my messages
>> first send an 8byte size packet.. So my read queue is constantly just doing
>>  ASize := StrToInt( '$'+ReadString(8) ) { 8 byte hex } and this is looping..
>> as soon as I get a successful size I can then read the specific size of data
>> into a message object and continue polling. If I need to send very large
>> data like binary files,, I break it down into smaller packets encapsulated
>> in messages using the above method.
>>
>> On Thu, Dec 4, 2008 at 9:31 AM, Eric A <eaa603 at hotmail.com> wrote:
>>
>> Kyley,
>>
>> No program design yet.  Questions:
>>
>> 1) Inside the thread - do I have to implement a timer event to
>> periodically check the buffer (since there's no "data received" event)?
>>
>> 2) What properties do I read to determine if there's received data
>> available?
>>
>> 3) Do I need to use another Indy component in conjunction with the
>> TCPClient for the buffering etc?
>>
>>
>> Paul,
>>
>> I'll take a look at that site.  Are you using ICS extensively?
>>
>>
>> Thanks,
>> Eric
>>
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Date: Thu, 4 Dec 2008 09:21:03 +1300
>> From: kyleyharris at gmail.com
>> To: delphi at delphi.org.nz
>> Subject: Re: [DUG] Indy Sockets - How to Receive Asynchronously
>>
>>
>> Indy is blocking, so typically on the client side, you would create a
>> waiting thread that you sit the TCPClient inside and loop a readtimeout
>> until the resultbuffer has some data. At that point produce a local event so
>> that your main thread can grab the TCPClient and read the information.
>>
>> without knowing your actual program design and how your TCP layer
>> interacts with your main application its hard to offer any detailed advise,
>> sorry.
>>
>> On Thu, Dec 4, 2008 at 9:14 AM, Paul <paul.blommaerts at telenet.be> wrote:
>>
>>  Indy works blocking only
>> Use ICS instead, they work blocking or non blocking.
>> check www.overbyte.be
>>
>> Paul
>>
>>   ----- Original Message -----
>> *From:* Eric A <eaa603 at hotmail.com>
>> *To:* Delphi UsersGroup <delphi at delphi.org.nz>
>> *Sent:* Wednesday, December 03, 2008 8:55 PM
>> *Subject:* [DUG] Indy Sockets - How to Receive Asynchronously
>>
>> I have a situation where I need to communicate with a communications
>> server using Indy TCP sockets.
>>
>> After sending the command the server returns an "OK" response with a
>> second or two to acknowledge the acceptance of the command, however the
>> reponse from the end device (returned via the server) may take several
>> minutes to eventuate (or a else the sever returns a timeout message).  I
>> need to be able to buffer the responses, be aware of when new strings
>> arrinve, and carry on with other tasks.  This threading aspect shouldn't be
>> an issue as I understand that Indy is naturally multitrheaded by design.
>>
>> I'm not familiar with using the Indy sockets and since there's no
>> "received data event" (due to the nature of the design) I'm wondering how I
>> capture the asynchronous responses sensibly?
>>
>> Does anyone have some code to show me how to use the Indy 10 TCPClient
>> component in this way (for the receive part) ?  Its probably pretty simple
>> but I need to get my head around it quickly.
>>
>> Thanks
>>
>> Eric
>>
>> ------------------------------
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>>
>> --
>> Kyley Harris
>> Harris Software
>> +64-21-671-821
>>
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>> --
>> Kyley Harris
>> Harris Software
>> +64-21-671-821
>>
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>
>
>
> --
> Kyley Harris
> Harris Software
> +64-21-671-821
>

-- 
Kyley Harris
Harris Software
+64-21-671-821
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