Re: [xSocket-develop] onData ?

[Gregor R. <gre...@go...>]

Hi Rod,

read mark is not necessary if you perform only a single read operation
within your onData method.

Each read operation on a non blocking connection can cause a
BufferUnderflowException. If you perform more than one read operation within
your handling code it is not predicable, if a BufferUnderflowException will
be thrown and when it will be thrown (by the 1. read operation, 2.te,...).
This BufferUnderflowException will be swallowed by xSocket

May be it becomes more clear by an example. The first read operation of the
example code reads a byte. Implicit the byte will be removed from the
internal xSocket read buffer. By calling the second read operation
readString a BufferUnderflowException could be thrown.
The onData method will be called again, if more data is received. By calling
the onData method the readByte method will be called again. Because the byte
has already be removed form the read buffer, the first byte of the string
will be returned.

This behaviour will not appear by using the read mark support.

      BadHandler implements IDataHandler {

         on Data(NonBlockingConnection nbc) {

            byte recordType = nbc.readByte();
            String version = nbc.readStringByDelimiter("\r\n");
            String signature = nbc.readStringByDelimiter("\r\n");
            int dataLength = nbc.readInt();
            ...
         }
       }







2008/5/7 Rod Magnuson <rod...@gm...>:

> It looks like the docs have changed since I started using xSocket. My
> onData implementation does
>
>         // reset to read position (if former reads failed) and mark it
>         connection.resetToReadMark();
>         connection.markReadPosition();
>
>         attempt to read datat that may or may not be thee
>
>         connection.removeReadMark();
>
>         process the data, only reached if a BufferUnderflowException
> wasn't throw
>
> Is the mark manipulation still necessary?
>
> Thanks,
> Rod
>
>
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