node.js - Nodejs sqs queue processor -


i trying write nodejs sqs queue processor. 

"use strict"; var appconf = require('./config/appconf'); var aws = require('aws-sdk'); aws.config.loadfrompath('./config/aws_config.json'); var sqs = new aws.sqs(); var exec = require('child_process').exec; function readmessage() {   sqs.receivemessage({     "queueurl": appconf.sqs_distribution_url,     "maxnumberofmessages": 1,     "visibilitytimeout": 30,     "waittimeseconds": 20   }, function (err, data) {     var sqs_message_body;     if (data.messages) {       if (typeof data.messages[0] !== 'undefined' && typeof data.messages[0].body !== 'undefined') {         //sqs msg body         sqs_message_body = json.parse(data.messages[0].body);         //make call nodejs handler in codeigniter         exec('php '+ appconf.ci_fc_path +'/index.php nodejs_handler make_contentq_call "'+ sqs_message_body.contentq_cat_id+'" "'+sqs_message_body.cnhq_cat_id+'" "'+sqs_message_body.network_id+'"',           function (error, stdout, stderr) {             if (error) {               throw error;             }             console.log('stdout: ' + stdout);             if(stdout == 'success'){               //delete message queue               sqs.deletemessage({                 "queueurl" : appconf.sqs_distribution_url,                 "receipthandle" :data.messages[0].receipthandle               });             }           });       }     }   }); } readmessage();

the above code works fine single message in queue. how should write script keeps polling messages in queue untill messages processed? should use set timeout?

first of should definetely use long polling technique provided amazon, , understand using because have "waittimeseconds": 20 argument in sqs.receivemessage call. hope didn't forget configure in aws web interface.

about polling messages - may use different techniques including timers, think simple call readmessage() function @ end of receivemessage's (or exec's) callback function. processing of (or waiting for) next message in queue start after end of processing of previous message in queue.

update:

as me in new version of code there many readmessage() calls. think better minimize keep code more clear , easy maintain. if leave, example, 1 call @ end of main receivemessage callback recieve lot of php worker scripts running in parallel - , maybe not bad point of view of performance - have add complicated script control amount of parallel workers. think can cut calls in exec callback, try join ifs , join calls in main callback. 

"use strict"; var appconf = require('./config/appconf'); var aws = require('aws-sdk'); aws.config.loadfrompath('./config/aws_config.json'); var delay = 20 * 1000; var sqs = new aws.sqs(); var exec = require('child_process').exec; function readmessage() {   sqs.receivemessage({     "queueurl": appconf.sqs_distribution_url,     "maxnumberofmessages": 1,     "visibilitytimeout": 30,     "waittimeseconds": 20   }, function (err, data) {     var sqs_message_body;     if (data.messages)        && (typeof data.messages[0] !== 'undefined' && typeof data.messages[0].body !== 'undefined')) {         //sqs msg body         sqs_message_body = json.parse(data.messages[0].body);         //make call nodejs handler in codeigniter         exec('php '+ appconf.ci_fc_path +'/index.php nodejs_handler make_contentq_call "'+ sqs_message_body.contentq_cat_id+'" "'+sqs_message_body.cnhq_cat_id+'" "'+sqs_message_body.network_id+'"',           function (error, stdout, stderr) {             if (error) {               // error handling              }             if(stdout == 'success'){               //delete message queue               sqs.deletemessage({                 "queueurl" : appconf.sqs_distribution_url,                 "receipthandle" :data.messages[0].receipthandle               }, function(err, data){                               });             }             readmessage();                           });       }               }             readmessage();           }); } readmessage();

about memory leaks: think should not worry because next call of readmessage() happens in callback function - not recursively, , recursively called function returns value parent function after calling receivemessage() function.


Comments

Post a Comment

Popular posts from this blog

How to mention the localhost in android -

i trying call localhost in android application. unfortunately not possible used several methods emulator local host http://10.0.2.2/android/dbconnection.php and network ip address http://192.168.1.xx/android/dbconnection.php also http://localhost:8080/android/dbconnection.php but nothing connected localhost. purpose refer stackoverflow answers not working i facing same problem when worked on localhost. referred stackoverflow answer got solution create new emulator works fine in new emulator.
Read more

php - Calling a template part from a post -

i include iframe within post in wordpress. located inside content of post, meaning cannot in post template file, otherwise either before or after. i'd add facebook plugin within posts: <div id="socialwrap"><div class="fb-like" data-href="http://onlinearizonahomes.info" data-send="true" data-width="450" data-show-faces="true" data-font="arial"></div></div> i thinking of calling template part within post <?php get_template_part( 'social' ); ?> cannot use php within post without plugin (i'd avoid using plugin this). an alternative using javascript create html in post, seems unnecessary use of javascript. what best way add html within wordpress post? you can use shortcode. add functions.php function cudjex_fbshare( $atts, $content = null ) { global $post; $link = get_permalink($post->id); return '<div id="socialwrap...
Read more

c# - String.format() DateTime With Arabic culture -

check below code snippet, namespace testdateconvertion { class program { static void main(string[] args) { datetime testvalue = new datetime(2013, 12, 15, 15, 33, 44); cultureinfo culture = new cultureinfo("ar-sa"); string stringvalue = string.format(culture, "{0:d} {0:hh:mm:ss}", testvalue); console.writeline(stringvalue); console.readline(); } } } it gives output 22/02/35 15:33:44 i not getting how possible. whats 35 doing in output there that's 13/12/2015 in hijri, 35 means 1435 in hijri, default date format saudi arabia.
Read more