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- Committer: Monty Taylor
- Date: 2010-09-26 21:24:15 UTC
- mto: (1796.1.2 build)
- mto: This revision was merged to the branch mainline in revision 1797.
- Revision ID: mordred@inaugust.com-20100926212415-5fn3p3q75pgiei7r
Moved protocol doc into the docs.
- files renamed:
- PROTOCOL => docs/protocol.rst
added
removed
docs/protocol.rst
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# the COPYING file in this directory for full text.
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#
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STATUS: This is currently a proposed draft as of November 29, 2008
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Drizzle Protocol
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----------------
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================
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`This is currently a proposed draft as of November 29, 2008`
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The Drizzle protocol works over TCP, UDP, and Unix Domain Sockets
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(UDS, also known as IPC sockets), although there are limitations when
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to be aborted gracefully (without having to close the connection)
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in the event of an error.
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|----------------------------- 32 Bits -----------------------------|
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|----------------|----------------|---------------------------------|
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0 | Magic | Protocol | Command ID |
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|----------------|----------------|---------------------------------|
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32 | Command / Result Code | Client ID Length |
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|---------------------------------|---------------------------------|
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64 | Client ID (optional, variable length) |
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|---------------------------------|---------------------------------|
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64+ | Chunk Length and Value Pairs (optional, variable length) |
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|---------------------------------|---------------------------------|
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64+ | Chunk Length = 0 |
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|---------------------------------|---------------------------------|
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80+ | Checksum |
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|-------------------------------------------------------------------|
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+-------------------------------------------------------------------------+
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+ 32 Bits +
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+-------------------------------------------------------------------------+
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+-----+----------------+----------------+---------------------------------+
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| 0 | Magic | Protocol | Command ID |
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+-----+----------------+----------------+---------------------------------+
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+-----+---------------------------------+---------------------------------+
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| 32 | Command / Result Code | Client ID Length |
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+-----+---------------------------------+---------------------------------+
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+-----+---------------------------------+---------------------------------+
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| 64 | Client ID (optional, variable length) |
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+-----+---------------------------------+---------------------------------+
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+-----+---------------------------------+---------------------------------+
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| 64+ | Chunk Length and Value Pairs (optional, variable length) |
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+-----+---------------------------------+---------------------------------+
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+-----+---------------------------------+---------------------------------+
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+ 64+ | Chunk Length = 0 | |
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+-----+---------------------------------+---------------------------------+
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+-----+---------------------------------+---------------------------------+
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| 80+ | Checksum |
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+-----+---------------------------------+---------------------------------+
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The first part of a packet is:
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2-byte Command/result code. For commands, this may be:
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1 ECHO - The entire packet is simply echoed back to the caller.
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2 SET - Set protocol options.
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3 QUERY - Execute query.
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4 QUERY_RO - Same as QUERY, but hints that this is a read-only
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query. This is only useful for routers/proxies who may want
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to redirect the request to a read slave.
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1 ECHO
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The entire packet is simply echoed back to the caller.
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2 SET
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Set protocol options.
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3 QUERY
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Execute query.
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4 QUERY_RO
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Same as QUERY, but hints that this is a read-only
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query. This is only useful for routers/proxies who may want
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to redirect the request to a read slave.
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Result codes may be:
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1 OK - Single packet success response. No data associated
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with the result besides parameters.
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2 ERROR - Single packet error response.
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3 DATA - Start of a multi-packet result set.
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3 DATA_END - Mark the end of a series of data packets. This is
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useful so a low level router or proxy can know when a
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response is complete without inspecting the contents of
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the packets.
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1 OK
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Single packet success response. No data associated
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with the result besides parameters.
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2 ERROR
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Single packet error response.
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3 DATA
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Start of a multi-packet result set.
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3 DATA_END
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Mark the end of a series of data packets. This is
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useful so a low level router or proxy can know when a
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response is complete without inspecting the contents of
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the packets.
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2-byte Client ID length.
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X-byte Client ID (length is value of client ID length). The client ID is
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there for the client and routers/proxies to use. The server
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treats this as opaque data, and will only preserve it to send
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in responses. This can be used as a sharding key, to keep
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state information in a proxy, or any other use.
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X-byte Client ID (length is value of client ID length).
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The client ID is there for the client and routers/proxies to use. The server
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treats this as opaque data, and will only preserve it to send
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in responses. This can be used as a sharding key, to keep
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state information in a proxy, or any other use.
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Next, zero or more chunks are given, terminated by a chunk length of
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0. Each chunk consist of a length and then that amount of data.
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