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Sending structure over network

Hi

I have some structures which I want to send to another computer on my network.
The structure includes strings and ordinal types.

Right now I'm inheriting a TComponent stores my data as published properties and then stream the component to a string and at the other side I convert the string to a component object. This works fine, but seems a bit dumb.

So any ideas how do it in a cleaner way.

I thought of using records but this is AFAIK not possible because of the strings. I want a generic procedure to stream my structure to data and then back again.

Lee_Nover

well you should never use any non-fixed-length strings in a record
hum..
if you still prefer records then make some "Header + data" protocol
you could make something like :

type
TmyRec = packed record
Param1,
Param2: Integer;
StringLength: Integer;
TheString: string;
end;

var myRec: TMyRec;

I don't know what you're using to write over network ...
(mailslots ?)so I'll just make some dummy procedure

procedure SendMyRec(rec: TMyRec);
begin
SendData(rec, SizeOf(rec));
if rec.StringSize > 0 then
SendData(rec.TheString[1], rec.StringSize);
end;

procedure GetMyRec(var rec: TMyRec);
begin
GetData(rec, SizeOf(rec));
if rec.StringSize > 0 then
begin
SetLength(rec.TheString, rec.StrngSize);
GetData(rec.TheString[1], rec.StringSize);
end;
end;

just an idea of how to do it :)

ASKER CERTIFIED SOLUTION

nestorua

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mfhobbs

Hi,

This is a good excuse to try some XML and put it on your resume. :) Use XML to package your data and conform to an industry standard! It is a very extendible format so you will find it easier in the long run.

Any web search should come up with lots of XML sites.

Basically your data is a simple string might look like (you can remove the linebreaks and spurious spacing):

<mydata>
<record><name>Fred</name><age>101</age></record>
<record><name>Joe</name><age>20</age></record>
...
<record><name>Sue</name><age>55</age></record>
</mydata>

Beats csv or fixed format as they don't allow nesting of data. See how XML is build around nesting. But, like other data formats, expressing links might be an issue...

You have to be careful to 'encode' any XML-special characters though.

You could override the TPersistent methods as described by Nestorua to do the XML too.

Cheers,

-Mat

mfhobbs

...just continuing from my post above:
Btw, there are several good Delphi free libraries around which will do the work of reading and writing to XML from a nested object structure (and worrying about any special encoding).

Cheers,
-Mat

SteveWaite

Good comments here! ;-)

bnz

ASKER

Sorry for not posting any comments before. I didn't receive any notification mail from E-E, probally my email problem.

I don't want to play around with XML, I think I want to go with nestoruas way. I will return when I run into trouble or have the solution made.

BTW Don't lock the question with an answer unless you are 100% sure that you posted what I needed.

bnz

ASKER

smurff

listening

pnh73

No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:

Accept answer from nestorua

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PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER!

Paul (pnh73)
EE Cleanup Volunteer