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 Transfering Stream Data using Remote Functions
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Total posts: 1
 Author Transfering Stream Data using Remote Functions
Danijel Tkalcec [RTC]

01.06.2006 21:17:27
Registered user
You can send streams with remote functions (limited length, since all data has to be kept in memory while sending and receiving) by using newByteStream to create the in-memory Stream, then using asByteStream (this is a TMemoryStream) to read/write data from the stream.

If you have components which write to a memory stream, you can pass “asByteSteam” as a parameter to those components methods/functions, so they can directly fill their content into the stream. On the other side, when the stream arrives, you can use “asByteStream” to access the data received.

Here are some examples …

EXAMPLE 1: Send a stream from a client to the server as a parameter in a remote function call …

On the client-side, to call the remote function, passing the stream as a parameter:
with myClientModule do
  begin
  with Data.newFunction(’callme’) do
    begin
    newByteStream(’mydata’);
    Some_Function_which_fills_the_stream(asByteStream[’mydata’]);
    end;
  Call(myResult);
  end;

And on the server side (OnExecute event), you can access all data inside your stream like this:
// need to make sure this parameter is a ByteStream …
if isType[’mydata’]=rtc_ByteStream then
  Some_Function_which_reads_from_stream(asByteStream[’mydata’]);

EXAMPLE 2: Send a stream as a result of a function call from the Server to the Client.

In server’s OnExecute event, create the stream and fill it with data:
Result.newByteStream;
Some_Function_which_fills_the_stream(Result.asByteStream);

And on the Client side (OnReturn event), you can access all data inside your stream like this:
// need to make sure this parameter is a ByteStream …
if Result.isType=rtc_ByteStream then
  Some_Function_which_reads_from_stream(Result.asByteStream);

EXAMPLE 3: Send a stream from Server’s OnExecute event as a result of a remote function call, now packed inside a record, so you can supply more information about data in that stream.

On the Server-side, you can write something like this:
with Result.newRecord do
  begin
  newByteStream(’mydata’);
  Some_Function_which_fills_the_stream(asByteStream[’mydata’]);
  end;

And on the Client side (OnReturn event), you can access all data inside your stream like this:
// need to make sure this parameter is a Record …
if Result.isType=rtc_Record then
  with Result.asRecord do
    begin
    // need to make sure this parameter is a ByteStream …
    if isType[’mydata’]=rtc_ByteStream then
      Some_Function_which_reads_from_stream(asByteStream[’mydata’]);
    end;