msgbus is a simple message bus that should run with a stock Python installation. Other than being written in Python, it is in no way tied to Python and it should be easy enough to use from any program.
Clients register themselves on a number of channels. A channel is simply a string.
Clients on a channel c will receive all messages sent to c or substrings of c.
In other words, if a client is registered on channel fooquux, it will receive
messages sent to fooquux as well as foo (and all other substrings of
fooquux).
The protocol is somewhat ad-hoc but should be simple enough to parse. Clients
can subscribe and unsubscribe to channels. They can send messages containing
arbitrary bytes to each other. In order for a client to start receiving messages,
it must notify the server with the listen message. It can stop receiving
messages with the unlisten command.
To subscribe to channels channel_1, channel_2, ..., channel_t, a client
sends a line of the form:
sub channel_1 channel_2 ... channel_t\n
The server responds with:
ack sub\n
To unsubscribe from channels channel_1, channel_2, ..., channel_t, a client
sends a line of the form:
unsub channel_1 channel_2 ... channel_t\n
The server responds with:
ack unsub\n
The client may send the message ping\n to which the server responds
with pong\n.
To send a message of x bytes to channels channel_1, channel_2, ..., channel_t,
a client first sends a line of the form:
send _x_ channel_1 channel_2 ... channel_t\n
After this, the client sends x bytes of the message are transmitted.
Clients that are registered on channels channel_1, channel_2, ..., channel_t
and that are listening will first receive the line:
recv _x_\n
followed by x bytes.
In order to receive messages, a client must first send the listen message.
The client can stop receiving messages by sending the unlisten message.
To start receiving data messages from the server, the client states its intent
by sending the message:
listen\n
to which the server responds:
ack listen\n
To stop receiving data messages from the server, the client states its intent
by sending the message:
unlisten\n
to which the server responds:
ack unlisten\n
If the client sends an invalid command, the server responds with the line:
error xxx\n
where xxx is an error message (without newlines).
George Sakkis for his trie implementation, PyTrie.