Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/wingify/lua-resty-rabbitmqstomp

Opinionated Lua RabbitMQ client library for the ngx_lua apps based on the cosocket API
https://github.com/wingify/lua-resty-rabbitmqstomp

Last synced: 5 days ago
JSON representation

Opinionated Lua RabbitMQ client library for the ngx_lua apps based on the cosocket API

Awesome Lists containing this project

README 

        
# Introduction



lua-resty-rabbitmqstomp - Lua RabbitMQ client library which uses cosocket api for

communication over STOMP 1.2 with a RabbitMQ broker which has the STOMP plugin.



# Limitations



This library is opinionated and has certain assumptions and limitations which

may be addressed in future;



- RabbitMQ server should have the STOMP adapter enabled that supports STOMP v1.2

- Assumption that users, vhost, exchanges, queues and bindings are already setup



# Status



This library is considered production ready for publishing reliable messages to

RabbitMQ.



# STOMP v1.2 Client Implementation



This library uses STOMP 1.2 for communication with RabbitMQ broker and

implements extensions and restrictions of the RabbitMQ Stomp plugin.



Internally, RabbitMQ uses AMQP to communicate further. This way the library

enables implementation of consumers and producers which communicate with the

RabbitMQ broker over STOMP, over AMQP. The protocol is frame based and has a

command, headers and body terminated by an EOL (^@) which consists of `\r` (013)

and required `\n` (010) over a TCP stream:



    COMMAND

    header1:value1

    header2: value2



    BODY^@



COMMAND is followed by EOL, then EOL separated header in key:value pair format

and then a blank line which is where the BODY starts and the frame is terminated

by ^@ EOL. COMMAND and headers are UTF-8 encoded.



## Connection



To connect we create and send a CONNECT frame over a TCP socket provided by the

cosocket api connecting to the broker IP, both IPv4 and IPv6 are supported. In

the frame we use login, passcode for authentication, accept-version to enforce

client STOMP version support and host to select the VHOST of the broker.



    CONNECT

    accept-version:1.2

    login:guest

    passcode:guest

    host:/devnode

    heart-beat:optional



    ^@



On error, an ERROR frame is returned for example:



    ERROR

    message:Bad CONNECT

    content-type:text/plain

    version:1.0,1.1,1.2

    content-length:32



    Access refused for user 'admin'^@



On successful connection, we are returned a CONNECTED frame by the broker, for

example:



    CONNECTED

    session:session-sGF0vjCKH1bLhFr6w9QwuQ

    heart-beat:0,0

    server:RabbitMQ/3.0.4

    version:1.2



For creating a connection, username, password, vhost, heartbeat, broker host and

port should be provided.



## Publishing



We can publish messages to an exchange with a routing key, persistence mode,

delivery mode and other header using the SEND command:



    SEND

    destination:/exchange/exchange_name/routing_key

    app-id: luaresty

    delivery-mode:2

    persistent:true

    content-type:json/application

    content-length:5



    hello^@



Note that content-length includes the message and EOL byte.



## Methods



### new



`syntax: rabbit, err = rabbitmqstomp:new({username = username,password = password, vost = vhost} )`



Creates a RabbitMQ object. In case of failures, returns nil and a string describing the error.



If nil table is supplied default values will be assumed on login:



- username: guest

- password: guest

- vhost: /



### set_timeout



`syntax: rabbit:set_timeout(time)`



Sets the timeout (in ms) protection for subsequent operations, including the connect method.

Note timeout should be set before calling any other method after creating the object.



### connect



`syntax: ok, err = rabbit:connect(host,port)`



Attempts to connect to a stomp broker the RabbitMQ STOMP adapter on a host, port is listening on.



### send



`syntax: rabbit:send(msg, headers)`



Publishers message with a set of headers. Note msg should be a string.



Some header values which can be set:



`destination`: Destination of the message, for example /exchange/name/binding

`persistent`: To delivery a persistent message, value should be "true" if declared

`receipt`: Receipt for confirmed delivery

`content-type`: Type of message, for example application/json



For list of supported headers see the STOMP protocol extensions and

restriction page: `https://www.rabbitmq.com/stomp.html`



### subscribe



`syntax: rabbit:subscribe(headers)`



Subscribe to a queue by using `headers`. It should have a id when persistent is

true. On successful subscription MESSAGE frames are sent by the broker.



### unsubscribe



`syntax: rabbit:unsubscribe(headers)`



Unsubscribes from a queue by using `headers`.

On successful unsubscription MESSAGE frames will stop coming from the broker.



### receive



`syntax: rabbit:receive()`



Tries to read any MESSAGE frames received and returns the message. Trying to receive

without a valid subscription will lead to errors.



### get_reused_times



`syntax: times, err = rabbit:get_reused_times()`



This method returns the (successfully) reused times for the current connection.

In case of error, it returns nil and a string describing the error.



If the current connection does not come from the built-in connection pool, then

this method always returns 0, that is, the connection has never been reused

(yet). If the connection comes from the connection pool, then the return value

is always non-zero. So this method can also be used to determine if the current

connection comes from the pool.



### set_keepalive



`syntax: ok, err = rabbit:set_keepalive(max_idle_timeout, pool_size)`



Puts the current RabbitMQ connection immediately into the ngx_lua cosocket connection pool.



You can specify the max idle timeout (in ms) when the connection is in the pool

and the maximal size of the pool every nginx worker process.



In case of success, returns 1. In case of errors, returns nil with a string describing the error.



Only call this method in the place you would have called the close method

instead. Calling this method will immediately turn the current rabbitmq object into

the closed state. Any subsequent operations other than connect() on the current

objet will return the closed error.



### close



`syntax: ok, err = rabbit:close()`



Closes the current RabbitMQ connection gracefully by sending a DISCONNECT to the

RabbitMQ STOMP broker and returns the status.



In case of success, returns 1. In case of errors, returns nil with a string describing the error.



## Examples



A simple producer that can send reliable persistent message to an exchange with

some binding:



    local strlen =  string.len

    local cjson = require "cjson"

    local rabbitmq = require "resty.rabbitmqstomp"

   

     

    local opts = { username = "guest",

                   password = "guest",

                   vhost = "/" }

 

    local mq, err = rabbitmq:new(opts)

    

    if not mq then

          return

    end



    mq:set_timeout(10000)



    local ok, err = mq:connect("127.0.0.1",61613) 

    

    if not ok then

        return

    end



    local msg = {key="value1", key2="value2"}

    local headers = {}

    headers["destination"] = "/exchange/test/binding"

    headers["receipt"] = "msg#1"

    headers["app-id"] = "luaresty"

    headers["persistent"] = "true"

    headers["content-type"] = "application/json"



    local ok, err = mq:send(cjson.encode(msg), headers)

    if not ok then

        return

    end

    ngx.log(ngx.INFO, "Published: " .. msg)



    local headers = {}

    headers["destination"] = "/amq/queue/queuename"

    headers["persistent"] = "true"

    headers["id"] = "123"



    local ok, err = mq:subscribe(headers)

    if not ok then

        return

    end



    local data, err = mq:receive()

    if not ok then

        return

    end

    ngx.log(ngx.INFO, "Consumed: " .. data)



    local headers = {}

    headers["persistent"] = "true"

    headers["id"] = "123"



    local ok, err = mq:unsubscribe(headers)



    local ok, err = mq:set_keepalive(10000, 10000)

    if not ok then

        return

    end



### resty-upstream pool example



	local cjson = require "cjson"

    local rabbitmq = require "resty.rabbitmqstomp"

    

	local mq, err = rabbitmq:new()

	

	if not mq then

		return nil, err

	end

	

	local mq, info = upstream_pool:connect(mq)

		

	if not mq then

		return nil, info

	end

	

	local msg = {key="value1", key2="value2"}

    local headers = {}

    headers["destination"] = "/exchange/test/binding"

    headers["receipt"] = "msg#1"

    headers["app-id"] = "luaresty"

    headers["persistent"] = "true"

    headers["content-type"] = "application/json"

    

	local ok, err = mq:send(cjson.encode(msg), headers)

		

	if not ok then

		return nil, err

	end

	

	ok, err = mq:set_keepalive(info.pool.keepalive_timeout,info.pool.keepalive_pool)

	

	

# TODO



- Write tests

- Check and parse replies from broker



# Author



Rohit "[bhaisaab](http://bhaisaab.org)" Yadav, [email protected]



# Contributing



Send a pull request on `https://github.com/wingify/lua-resty-rabbitmqstomp`



You may contact the author and the [Openresty community](https://groups.google.com/forum/?fromgroups#!forum/openresty-en)



# Copyright and License



This module is licensed under the MIT license.



Copyright 2013 Rohit "[bhaisaab](http://bhaisaab.org)" Yadav, [Wingify](http://engineering.wingify.com/opensource)



Permission is hereby granted, free of charge, to any person obtaining

a copy of this software and associated documentation files (the

"Software"), to deal in the Software without restriction, including

without limitation the rights to use, copy, modify, merge, publish,

distribute, sublicense, and/or sell copies of the Software, and to

permit persons to whom the Software is furnished to do so, subject to

the following conditions:



The above copyright notice and this permission notice shall be

included in all copies or substantial portions of the Software.



THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND

NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE

LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION

WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.



# See Also



- [STOMP 1.2 Spec](http://stomp.github.io/stomp-specification-1.2.html)

- The [resty-upstream](https://github.com/hamishforbes/lua-resty-upstream) library

- The [lua-resty-mysql](https://github.com/agentzh/lua-resty-mysql) library

- [Openresty google group](https://groups.google.com/forum/?fromgroups#!forum/openresty-en)