AMQP Specification Transport

AMQP Specification.
Connection
3 Connection
3.1 Version Negotiation
Prior to sending any frames on a connection, each peer MUST start by sending a protocol header that
indicates the protocol version used on the connection. The protocol header consists of the upper case ASCII
letters "AMQP" followed by 1, 0, 0, and connection flags. This is an 8-octet sequence:
4 OCTETS 1 OCTET 1 OCTET 1 OCTET 1 OCTET
+----------+---------+---------+----------+---------+
| "AMQP" | major | minor | revision | flags |
+----------+---------+---------+----------+---------+
flags: 0|0|0|0|0|0|R|S
R: tls-required -- The peer requires all data following the
connection header to be encrypted. If R is
set then S MUST also be set.
S: tls-supported -- Indicates that the peer supports TLS
encryption. If either peer's connection
header has the R flag set then all
connection data following the connection
header will be encrypted, otherwise
connection data will be unencrypted.
Note: if one protocol header requires TLS, and the other does
not support it, then both peers MUST abort the connection.
An AMQP client and server agree on a protocol version as follows:
• When the client opens a new socket connection to an AMQP server, it MUST send a protocol
header with the client's preferred protocol version.
• If the requested protocol version is supported, the server MUST send its own protocol header with
the requested version to the socket, and then implement the protocol accordingly.
• If the requested protocol version is not supported, the server MUST send a protocol header with a
supported protocol version and then close the socket.
• When choosing a protocol version to respond with, the server SHOULD choose the highest
supported version that is less than or equal to the requested version. If no such version exists, the
server SHOULD respond with the highest supported version.
• If the server can't parse the protocol header, the server MUST send a valid protocol header with a
supported protocol version and then close the socket.
Based on this behavior a client can discover which protocol versions a server supports by attempting to
connect with its highest supported version and reconnecting with a version less than or equal to the version
received back from the server.
AMQP Transport v. 1-0 Page 6 of 83