Open Data Element (ODE)

Karthik Ayyar karthik@houseofkodai.in

20131230

1. Introduction =============== An Open Data Element (ODE) is a self-defining structure of data that is easy to generate and safe to parse.

   ODE is a basic building block for file-formats and network-protocols. Network-protocols are essentially exchange of ODE between peers; This ODE eXchange is known as OX. A network of nodes communicating ODEs via. OX is known as Open Data Interface Network (ODIN).

   Although each element would seem restricted in size of upto 65533 (2^16:65536-3) bytes, any length of data can be accomodated by encoding it as a sequence of fragmented ODEs. For example, a 2-byte fragmentation-header (id/count) extends the maximum size of each element to, almost 16MB (256 * 65531 = 16775936 bytes).

   ODE can be used recursively; an ODE can contain other ODEs.

   Defining file-formats and network-protocols is as simple as defining the ODE type-table. It is anticipated that application developers will publish ODE type-tables encouraging interoperability.

2. Definition =============

[Size] [[Type] [Data]]

[Size]

• 2 bytes
• for UDP packets, refers to sequence number, as size is implicit intended for jitter-buffers to deal with out-of-order/delayed packets.

[Type]

• 1 byte
• 1 bit of fragment-flag (highest-bit fragment-flag)
• 7 bits of type (decimal values 0-127)

[Data]

• (size-1) bytes

note:

• all bytes are Network byte order
• for textual formats size and type can be specified as %%type\n enabling easy parsing/translation of %%type\n into 3-byte [size][type]
• human readable text formats can use \n as type-data seperator and characters between type and \n as a comment
• human readable type definition is either printable character or \nnn numeric value of type (0-127)

3. Reserved Type Table Definition (0.ode) ========================================= Type Description

   58 : Type-table definition [* 0-or-more bytes space delimiter] [numeric-string ASCII value (<127) of Type] [1+ bytes space delimiter] [description] [2 byte \n\n new-line new-line description terminator]

   0 Block of Bytes [description] [1 byte \0 null terminator] [data bytes] useful for encapsulating files.

   42 * Group of elements [numeric-string number of elements] [1 byte space delimiter] [zero or more ODElements] multiplex multiple elements into a single element/packet

   46 . Pointer/Index to previous element [2-byte previous-element-offset] [(size-2) bytes unique-marker] random-file-seek: search for unique-marker and then traverse first to previous-element and then to other elements as required.

   33 ! Identity Element 1-byte space delimited words [id] [status] [params...] ! karthik idle version x microphone camera tv speaker

   63 ? Request [reQuest id] [1 byte space delimiter] [command] [1 byte space delimiter] [params...]

   61 = Response-pending [reQuest id] [pending status descripton]

   43 + Response-success [reQuest id] [1 byte space delimiter] [response data]

   45 - Response-failure [reQuest id] [1 byte space delimiter] [error code numeric] [1 byte space delimiter] [error code description]

   62 > Response-redirect [reQuest id] [1 byte space delimiter] [redirect URL]