This was part of the subject MAC5910 (Network Programming) at IME-USP.
- Unix-like operating system (tested: Manjaro Linux, Debian and Mac OS) with
pthreadsupport - C compiler (tested:
gccandclang) - GNU Make
- Little-endian processor (tested: Intel x86 64bit, ARM 32bit and ARM 64bit)
- AMQP 0.9.1
- No authentication
- Do not send exchange messages
- Send ACK after consume
Tested: amqp-tools and python-aqmp.
The file config.h contains some configuration constants, which set up the
code in compilation time. In that file, you can set, for example, the maximum
number of connections and the maximum length of the queue names.
Just run make on the project root.
Once built, just run ./amqp_broker <port> on the project root.
AMQP is a stateful protocol, so it's natural that we keep the connection control using a state machine.
Each state machine is created after the beginning of the connection with the client, starting in the state WAIT. In that state, it waits for the protocol header.
The last state of the connection is FINISHED, when the connection finishes gracefully. There is also a FAIL state, if something goes wrong.
The state machine is described in state_machine.c e state_machine.h.
The FAIL stated is hidden here in order to simplify the diagram, as any state may have a event that leads to it.
The connection establishment states are the following:
*--------* *------------* *------------*
| WAIT | -------------------> | HEADER | --------> | WAIT |
| | C: Protocol Header | RECEIVED | S: Start | START OK |
*--------* *------------* *------------*
|
C: Start OK |
|
*-----------------* *-----------* *------------* |
| WAIT |<---------- | WAIT | <-------- | START OK | <--
| OPEN CONNECTION | C: Tune Ok | TUNE OK | S: Tune | RECEIVED |
*-----------------* *-----------* *------------*
|
| C: Open Connection
|
| *-----------------* *-----------------*
--> | OPEN CONNECTION | ----------------------> | OPEN CONNECTION |
| RECEIVED | S: Open Connection OK | RECEIVED |
*-----------------* *-----------------*
|
C: Open Channel |
|
*-------------* *--------------* |
| WAIT | <--------------------- | OPEN CHANNEL | <---
| FUNCTIONAL | S: Open Channel OK | RECEIVED |
*-------------* *--------------*
|
| C: Método
|
|-> Queue declare states
|
|-> Publish states
|
-> Consume states
After the state WAIT FUNCTIONAL, it can close the connection, or take one of these different paths:
- queue declare
- publish
- consume
Each one of them can begin the connection closing in its states. This will also be hidden here in order to simplify the diagram.
The queue declaration states are the following:
*------------* *---------------*
| WAIT | -------------------> | QUEUE DECLARE |
| FUNCTIONAL | C: Queue Declare | RECEIVED |
| | | |
| | <------------------ | |
| | S: Queue Declare OK | |
*------------* *---------------*
The publish states are the following:
*------------* *---------------* *----------------*
| WAIT | -------------------> | BASIC PUBLISH | -> | WAIT PUBLISH |
| FUNCTIONAL | C: Basic Publish | RECEIVED | | CONTENT HEADER |
*------------* *---------------* *----------------*
^ |
C: Basic Publish | C: Content Header |
| |
| *----------------* |
|-------- | WAIT PUBLISH | <-
| | CONTENT |
-------> | |
C: Body | |
*----------------*
The consume states are the following:
*------------* *---------------*
| WAIT | ----------------> | BASIC CONSUME |
| FUNCTIONAL | C: Basic Consume | RECEIVED |
*------------* *---------------*
|
| S: Basic Consume OK *------------*
---------------------> | WAIT VALUE |
-----------------------------------------> | DEQUEUE |
| C: Consume Ack *------------*
| |
| |
| Q: Dequeue |
| |
*--------------* *---------------* |
| WAIT CONSUME | <------------------- | VALUE DEQUEUE | <--
| ACK | S: Basic Deliver | RECEIVED |
| | S: Content Header | |
| | S: Body | |
*--------------* *---------------*
The connection close can be started on several states when they receive close channel or close connection messages:
*---------------* *-----------*
----------------> | CLOSE CHANNEL | -------------------> | WAIT OPEN |
C: Close Channel | RECEIVED | S: Close Channel OK | CHANNEL |
*---------------* *-----------*
*------------------* *----------*
-------------------> | CLOSE CONNECTION | ----------------------> | FINISHED |
C: Close Connection | RECEIVED | S: Close Connection OK | |
*------------------* *--------- *