###A simple message queue written in C.

The server (server.c) is written to be async and handle any generic callback function. This allows it to wrap things that aren't queues (e.g. a bloom filter).

The router component (mq_router.c) is what maps strings received by the server to commands from the data structure. To use a different data structure, a new router needs to be created.

Main.c ties the server to the router and data structure, by calling create_server and passing the router handler function, along with a pointer to the data structure as (void *) state.

The client (client.c) is also written to be generic, and simply sends strings to a specified socket.

mq_client maps intents to strings. So, for example, a call to push("this") will send the string "PUSH this" to the client which will send it to the server.

cmd.c is a simple command line app that wraps mq_client. E.g. $ cmd -u "This long string" will send the command "PUSH This long string" to the server via the client's socket.

Defintion of the protocol happens in the router, and the client must adhere to it. The server will append a NULL to the end of the recieved buffer, so string operations on that buffer should be generally safe.

The protocol that the message queue adheres to has statements that are delimited by newlines (\n). This means that input with newlines will be interpreted incorrectly, and information after the newline is likely to be lost. For this reason, it's recommended that you use JSON to encode and decode the messages.

The push command takes the form "PUSH $body". $body will then be added to the queue.

The pop command takes the form "POP" with no arguments. The server will then return the message at the front of the queue.

There is a persistence layer that each structure is responsible for. The message queue structure implements this and serializes the queue to disk after each transaction. Upon starting the program, we will attempt to deserialize the queue from disk if possible.

This file has helper functions that make it easy to read and write from disk. Each structure should have methods to serialize and deserialize the structure to and from a char * buffer, respectively.

For an example usage, see mq_persist.c.

credits to @coreylynch for the bloom* files and implementation. credits to @itairos for inspiring me to be asynchronous.