schema.fbs

// This schema defines the layout of binary data for messages in the SSB-Archive format using the ssb-bipf2 format.

include "core.fbs";
include "structs.fbs";
include "dictionaries.fbs";
include "classic-format.fbs";

// The FormatSpecificBlockSketch union allows for the inclusion of future message formats in the SSB-Archive format.
union FormatSpecificBlockSketch {
    ClassicMessageBlockSketch,
    // future formats
}

// The FormatSpecificBlockSketch unions allows for the inclusion of future message formats in the SSB-Archive format.
union FormatSpecificBlockData {
    ClassicMessageBlock,
    // future formats
}

// The MessageBlockSketch and MessageBlock tables contain the metadata for a block of messages, including the number
// of messages, the sequence number and timestamps of the first and last messages, and the delta between the timestamps of the messages.
table MessageBlockSketch {
  length: uint32; // this is the number of messages in this block
  sequence_number_base: uint32; // this is the sequence number of the first message in this block
  first_timestamp: uint64; // this is the timestamp of the first message in this block
  last_timestamp: uint64; // this is the delta between the last message and the previous message
}

table MessageBlock {
  sketch: MessageBlockSketch;
  timestamp_deltas: StreamVByteArray1248; // are the deltas between the timestamps of the messages in this block.
  types: RunLengthCodedDictionaryColumn; // this is the type of each message in this block (using a dictionary). In column to allow fast scans.

  data: FormatSpecificBlockData;

  sequence_numbers: StreamVByteArray1234; // this is the array of sequence numbers (optional, if absent, the sequence numbers are assumed to be consecutive, this in case the format is used for other purposes than ssb-archive)
}

// The MessageBlockRef table contains a reference to a MessageBlock, including its blobId hash and sketch metadata.
table MessageBlockRef {
  blob_id: Sha512256Hash;
  sketch: MessageBlockSketch;
  previous: MessageBlockRef;
}

// The Bundle table contains an array of MessageBlockRefs, as well as references to dictionaries for types,
// object keys, object paths, and object signatures.
table Bundle {
  message_blocks: [MessageBlockRef];

  type_dictionary: StringDictionaryRef; // this is the dictionary for the types
  object_key_dictionary: StringDictionaryRef;
  object_path_dictionary: IntArrayDictionaryRef;
  object_signature_dictionary: IntArrayDictionaryRef;
}

union Bip2BlobData {
  MessageBlock,
  StringDictionary,
  IntArrayDictionary,

  Bundle
}

// The Bip2Blob table is the root type of the schema, and it contains data of various types, including MessageBlocks, dictionaries, and Bundles.
table Bip2Blob {
  data: Bip2BlobData;
}

file_identifier "BIP2";
file_extension "bipf2";
root_type Bip2Blob;