Distributed Information System (DIS)
  • Home
  • The blog
  • Contact

Bleams explained...

6/12/2007

1 Comment

 

IDR is the data encoding used with DITP. It is to DITP what XML is to SOAP. IDR uses bleams that combines the benefits of block and stream encoding:

   - no need to specify total size in front of it
   - no upper size limit
   - may be encapsulated without depth limit
   - no constrain on data and doesn't rely on markers or tags
   - no need to parse and search payload data to locate the end of bleam

A bleam is encoded as a sequence of byte blocks of at most 16KB. Each block is preceded by an unsigned short value whose 14 less significant bits encodes the number of bytes of data that follow. Its most significant bit is set to one if the block is not first, and its second most significant bit is set to one if the block is not last.

When encapsulating a bleam, its sequence of blocks is simply inserted in the sequence of blocks of the encapsulating bleam. The encapsulated bleam can be stored in the data of the the encapsulating bleam block if it fully fits in one of its block.

The maximum payload size is 16382 so that the biggest block will be 2^14 byte long. The invalid size value 16383 (0x3FFF) is then used as a signal. A signal block has no payload data.

The signal is used in IDR to inform the receiver that the expected sequence of data is interrupted because an exception or an error occured. If the signal block is flagged as end of bleam, the interruption is anonymous. Otherwise subsequent bleam data provides information on the reason of the interruption. In IDR it is the serialized exception object and the objects it may be referencing. Such interruption will eventually propagate to encloding bleams and be encoded as anonymous interruptions.

Encoding and decoding bleams require some care, but the effort is worth it because of its multiple benefits. With small messages DITP is as performant as common inter-object communication protocols. With bigger message, DITP benefits from the stream oriented encoding and reduced latency and memory usage requirements. DITP can thus be used to send huge files, streamed films, etc.

1 Comment
Nickmorel Listudio link
7/26/2023 12:13:01 am

Thank yoou for sharing this

Reply



Leave a Reply.

    Author

    Christophe Meessen is a  computer science engineer working in France.

    Any suggestions to make DIS more useful ? Tell me by using the contact page.

    Categories

    All
    Business Model
    Database
    Dis
    Ditp
    Dvcs
    Git
    Gob
    Idr
    Misc
    Murphys Law
    Programming Language
    Progress Status
    Startup
    Suggested Reading
    Web Site

    Archives

    December 2017
    November 2015
    September 2015
    February 2013
    December 2012
    November 2012
    May 2012
    February 2012
    March 2010
    October 2009
    September 2009
    July 2009
    June 2009
    May 2009
    February 2009
    January 2009
    November 2008
    September 2008
    August 2008
    July 2008
    May 2008
    April 2008
    March 2008
    February 2008
    January 2008
    December 2007
    October 2007
    August 2007
    July 2007
    June 2007
    May 2007

    RSS Feed

    Live traffic feed
    You have no departures or arrivals yet. Wait a few minutes and check again.
    Powered by FEEDJIT
Powered by Create your own unique website with customizable templates.