PHP and Erlang interaction through RabbitMQ

Introduction

The more you program in php, the more often you come across tasks for which you need a server daemon. Yes, of course there is phpDaemon, cron or crutches, which at each n-th script launch invoke some particular set of operations. But when we talk about projects with a load more than on a regular site, we start to get upset.

In one of the projects, we decided to use a bunch of php + RabbitMQ + erlang to solve this problem. The necessary functionality has already been written on php, we just had to post calls on time and on different machines. Specifically, the task sounded like this: write a users' parser from an external data storage and, most importantly, keep the data up-to-date, and if changed, send notifications.

Initial data

- Rest-function on php, adding a user to favorites. From this list in the future, and users will be formed, the relevance of the information which we will support, and in case of change - send notifications to the client.
- An application on erlange, which should coordinate which users we are currently processing, etc. Processing information from an external source is carried out in two ways - this is parsing html pages or, where possible, api requests. To process the replies, use the rest function written in php.
- We must support the ability to easily scale to a large number of servers. The list of users who need to be parsed is in queues formed by RabbitMQ.

Task number 1 - configure the php extension to work with RabbitMQ

First of all, install additional software packages:
')

apt-get install gcc apt-get install php5-dev 

Next, the installation itself, found on the Internet:

 #download and install the rabbitmq c amqp lib wget https://github.com/alanxz/rabbitmq-c/releases/download/v0.5.1/rabbitmq-c-0.5.1.tar.gz tar -zxvf rabbitmq-c-0.5.1.tar.gz cd rabbitmq-c-0.5.1/ ./configure make sudo make install cd .. #download and compile the amqp wget http://pecl.php.net/get/amqp-1.4.0.tgz tar -zxvf amqp-1.4.0.tgz cd amqp-1.4.0/ phpize && ./configure --with-amqp && make && sudo make install #Add amqp extension to php mods-availabile directory echo "extension=amqp.so" > /etc/php5/mods-available/amqp.ini #Enabled it in cli cd /etc/php5/cli/conf.d/ ln -s ../../mods-available/amqp.ini 20-amqp.ini php -m | grep amqp #Enabled it in cli cd /etc/php5/apache2/conf.d/ ln -s ../../mods-available/amqp.ini 20-amqp.ini #restart Apache and than check phpinfo on web service apache2 restart 

If you are lucky, then everything is set right.

Task number 2 - install RabbitMQ and its web-based control panel

 sudo apt-get install rabbitmq-server rabbitmq-plugins enable rabbitmq_management rabbitmqctl stop rabbitmq-server -detached 

Further to this address you get access to queue management, by default login (guest) and password (guest)
ip.addres : 15672 /

Task number 3 - via php to influence the RabbitMQ queues

 //   $rabbit = new AMQPConnection(array('host' => '127.0.0.1', 'port' => '5672', 'login' => 'guest', 'password' => 'guest')); $rabbit->connect(); $testChannel = new AMQPChannel($rabbit); $exchange = new AMQPExchange($testChannel); $exchange->setName('logoooooo'); $exchange->setType(AMQP_EX_TYPE_DIRECT); $exchange->declare(); //  $testChannel = new AMQPChannel($rabbit); $queue = new AMQPQueue($testChannel); $queue->setName("yyyyyyy2"); $queue->declare(); //     $testChannel = new AMQPChannel($rabbit); $queue = new AMQPQueue($testChannel); $queue->setName("yyyyyyy2"); $queue->bind('logoooooo'); $queue->declare(); //    $testChannel = new AMQPChannel($rabbit); $exchange = new AMQPExchange($testChannel); $exchange->setName('logoooooo'); $exchange->publish('pooooooooooooooooooooooooooooooo'); 

Task number 4 - Create an application on erlange using rebar

Install rebar

 apt-get install rebar mkdir 1 rebar create template=simpleapp srvid=my_server46 rebar create template=simplesrv srvid=my_server46 

Task number 5 - Run the application on erlange

First install CMake:

 apt-get install make 

In the Makefile, write the following:

 all: rebar compile run: ERL_LIBS=deps erl +K true -name myapp_app@127.0.0.1 -boot start_sasl -pa ebin -s myapp_app -sasl errlog_type error 

The line -pa ebin -s myapp_app means that we start ebin / myapp_app.erl and in it the function myapp_app: start ().
ERL_LIBS = deps means that we load all the libraries that are located in the deps folder.

Task number 6 - connect the necessary libraries for communication between RabbitMQ and Erlang

In rebar.config put the following:

 {deps, [ {rabbit_common, ".*", {git, "git://github.com/jbrisbin/rabbit_common.git", {tag, "rabbitmq-3.0.2"}}} ]}. {erl_opts, [ debug_info, compressed, report, warn_export_all, warn_export_vars, warn_shadow_vars, warn_unused_function, warn_deprecated_function, warn_obsolete_guard, warn_unused_import % warnings_as_errors ]}. 

We execute rebar get-deps, pull up dependences. Then there were difficulties with the remaining libraries, so I had to use what is written on the official RabbitMQ website. But before these, we reinstall the necessary packages:

 apt-get install xsltproc apt-get install zip 

After we go into the deps daddy, which was created by rebar and, using git, we download everything, and after that we install:

 cd deps git clone https://github.com/rabbitmq/rabbitmq-erlang-client.git git clone https://github.com/rabbitmq/rabbitmq-server.git git clone https://github.com/rabbitmq/rabbitmq-codegen.git cd rabbitmq-erlang-client make 

Task number 7 - from Erlang to receive messages from the RabbitMQ queues

The file myapp_app.erl is left a little bit editable so that you can run from the makefile that we wrote:

 -module(myapp_app). -behaviour(application). -export([start/0,start/2, stop/1]). start() -> myapp_sup:start_link(). start(_StartType, _StartArgs) -> myapp_sup:start_link(). stop(_State) -> ok. 

The file myapp_sup.erl, which is responsible for monitoring processes, appends the call to our module from init:

 -module(myapp_sup). -behaviour(supervisor). -export([start_link/0]). -export([init/1]). -define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}). start_link() -> supervisor:start_link({local, ?MODULE}, ?MODULE, []). init([]) -> {ok, { {one_for_one, 5, 10}, [{my_server46_0, {my_server46, start_link, []},permanent, brutal_kill, worker, [my_server46]}]} }. 

Module responsible for communicating with RabbitMQ:

 -module(my_server46). -behaviour(gen_server). -include("deps/rabbitmq-erlang-client/include/amqp_client.hrl"). -define(SERVER, ?MODULE). -export([start_link/0,main/0,loop/1]). -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2, code_change/3]). start_link() -> gen_server:start_link({local, ?SERVER}, ?MODULE, [], []). init(Args) -> main(), {ok, Args}. main() -> {ok, Connection} = amqp_connection:start(#amqp_params_network{host = "localhost"}), {ok, Channel} = amqp_connection:open_channel(Connection), io:format(" [*] Waiting for messages. To exit press CTRL+C~n"), amqp_channel:call(Channel, #'basic.qos'{prefetch_count = 1}), amqp_channel:subscribe(Channel, #'basic.consume'{queue = <<"yyyyyyy2">>},self()), receive #'basic.consume_ok'{} -> io:fwrite(" _rec_main_ok_ "),ok end, loop(Channel), io:fwrite("begin~n", []). loop(Channel)-> receive {#'basic.deliver'{delivery_tag = Tag}, #amqp_msg{payload = Body}} -> Dots = length([C || C <- binary_to_list(Body), C == $.]), io:format(" [x] Received Body ~p~n", [Body]), receive after Dots*1000 -> io:format(" _loop_rec_after_ ~p",[0]), ok end, timer:sleep(3500), amqp_channel:cast(Channel, #'basic.ack'{delivery_tag = Tag}), loop(Channel), io:format(" [x] Done 3~n") end. handle_call(_Request, _From, State) -> {reply, ok, State}. handle_cast(_Msg, State) -> {noreply, State}. handle_info(_Info, State) -> {noreply, State}. terminate(_Reason, _State) -> ok. code_change(_OldVsn, State, _Extra) -> {ok, State}. 

Everything is simple enough, we subscribe to the queue "yyyyyyy2":

 amqp_channel:subscribe(Channel, #'basic.consume'{queue = <<"yyyyyyy2">>},self()) 

Then we inform RabbitMQ that the message was successfully processed:

 amqp_channel:cast(Channel, #'basic.ack'{delivery_tag = Tag})