Message synchronization

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1

Imported from previous forum

2

Hi,

Is there a possibility to find the next message beginning if I start reading FAST-compressed stream from arbitrary point (not from beginning of current message)? In this case message template is unknown and I could not use information about message structure.

Thanks,
Konstantin Stepanyuk

3

In the general case, no. If you know something more about the stream, you can possibly apply some heuristic searching but there is nothing that stops a pmap followed by an integer in a subgroup of a message to look exactly as the pmap+tid combo appearing at the topmost level of a stream.

/David

Hi,

Is there a possibility to find the next message beginning if I start
reading FAST-compressed stream from arbitrary point (not from beginning
of current message)? In this case message template is unknown and I
could not use information about message structure.

Thanks, Konstantin Stepanyuk

4

I have done this with limited success. The best you can do is search for a point in the stream where you have received a message for a specific template with specific fields present. This would indicate that a reset was issued by the sender. At this point, there would be a unique signature for pmap+templateID+[specific fields and field characteristics]. This is not guaranteed, and individual field validation is often required.

/Daniel

In the general case, no. If you know something more about the stream,
you can possibly apply some heuristic searching but there is nothing
that stops a pmap followed by an integer in a subgroup of a message
to look exactly as the pmap+tid combo appearing at the topmost level
of a stream.

/David

Hi,

Is there a possibility to find the next message beginning if I start
reading FAST-compressed stream from arbitrary point (not from
beginning of current message)? In this case message template is
unknown and I could not use information about message structure.

Thanks, Konstantin Stepanyuk