FineDB

Protocol

The communication between FineDB client and server is based on a binary protocol. Requests start with a byte which describes the command and its options. This byte may be followed by other data, depending on the request type.

Responses start also with a byte containing a result code and some useful information. This byte may be followed by other data, depending on the request type and the result of the request processing.

Request byte

1 1 1 1 1 1 1 1
| | | | | | | |
| | | | `--------> command [1]
| | | |
| | | `----------> synchronous [2]
| | |
| | `------------> serialized data [3]
| |
| `--------------> compression [4]
|
`----------------> server to server command [5]

[1]: Request command.

  • 0000 ➔ PING (check the connection)
  • 0001 ➔ GET (get a data from its key)
  • 0010 ➔ DEL (delete a key/value pair)
  • 0011 ➔ PUT (add or update a key/value)
  • 0100 ➔ SETDB (set database name for subsequent requests)
  • 0101 ➔ START (start a transaction)
  • 0110 ➔ STOP (stop a transaction)
  • 0111 ➔ not defined yet
  • 1000 ➔ not defined yet
  • 1001 ➔ not defined yet
  • 1010 ➔ not defined yet
  • 1011 ➔ not defined yet
  • 1100 ➔ not defined yet
  • 1101 ➔ not defined yet
  • 1110 ➔ ADMIN (administration command)
  • 1111 ➔ EXTRA (other command expressed in a second request byte)

[2]: Synchronous request.
[3]: Data are serialized (PUT/ADD/UPDATE request only).
[4]: Compression option.

  • GET command ➔ the client accepts compressed data.
  • PUT command ➔ compressed data are sent.

[5]: Replication between servers.

Response byte

/------------> unused bit [1]
|
1 1 1 1 1 1 1 1
  | | | | | | |
  | | | | | | `--> status bit [2]
  | | | | | |
  | | `----------> error code [3]
  | |
  | `------------> serialized data [4]
  |
  `--------------> compression [5]

[1]: Free for future usage.
[2]: Status of the request processing.

  • 0 ➔ error
  • 1 ➔ OK

[3]: Type of the encountered error.

  • 0000 ➔ undefined error
  • 0001 ➔ protocol error
  • 0010 ➔ server error
  • 0011 ➔ full database
  • 0100 ➔ too many opened databases
  • 0101 ➔ bad name (dbname for SETDB request, key for GET or DEL request)
  • 0110 ➔ transaction error

[4]: Returned data are serialized (GET request only).
[5]: Returned data are compressed (GET request only).