Useful links for javascript and nodejs

To understand the event loop

Node.js is a single-threaded application, but it can support concurrency via the concept of event and callbacks. Every API of Node.js is asynchronous and being single-threaded, they use async function calls to maintain concurrency. Node uses observer pattern. Node thread keeps an event loop and whenever a task gets completed, it fires the corresponding event which signals the event-listener function to execute.

To understand the basics of the event loop please refers these links which are very useful for to under stand the event loop deeply.











Javascript tutorials links



Nodejs tutorials best links


Nodejs instrumentation tutorials links















Comments

Post a Comment

Popular posts from this blog

Proxy setting in java

3 properties can set in http,https and ftp proxy handler Http proxy in java 1. http.proxyHost: the host name of the proxy server 2. http.proxyPort: the port number, the default value being 80. 3. http.nonProxyHosts:a list of hosts that should be reached directly, bypassing the proxy. Add http proxy when run main class 1. $ java -Dhttp.proxyHost=webcache.example.com GetURL 2. $ java -Dhttp.proxyHost=webcache.example.com -Dhttp.proxyPort=8080 -Dhttp.nonProxyHosts=”localhost|host.example.com” GetURL Add https proxy when run main class 1. $ java -Dhttps.proxyHost=webcache.example.com GetURL 2. $ java -Dhttps.proxyHost=webcache.example.com -Dhttps.proxyPort=8080 -Dhttp.nonProxyHosts=”localhost|host.example.com” GetURL Add http proxy in java code //Set the http proxy to webcache.example.com:808 0 System.setProperty("http.proxyHost", "webcache.example.com"); System.setProperty("http.proxyPort", "8080"); System.setProperty("...
Read more

Using logstash to import csv json files into elasticsearch

Using logstash to import csv files into elasticsearch test.csv file contains these data's 01/01/2012 12:01:00 AM,18900 TIMES AV,SAN LORENZO,CA,94541,290,VANDALISM ($400 OR MORE),ACSO,12000048,"(37.67705445, -122.11298064)" 01/01/2012 12:01:00 AM,21000 SHERMAN DR,CASTRO VALLEY,CA,94552,250,FORGERY,ACSO,13006643,"(37.71437982, -122.02231781)" 01/01/2012 12:03:00 AM,A ST / MISSION BL,HAYWARD,CA,94541,999,REPORT NUMBER WAS CANCELLED,ACSO,11021284,"(37.66655037, -122.10000611)" 01/01/2012 12:03:00 AM,A ST / MISSION BL,HAYWARD,CA,94541,999,REPORT NUMBER WAS CANCELLED,ACSO,12000010,"(37.66655037, -122.10000611)" 01/01/2012 12:03:00 AM,A ST / MISSION BL,HAYWARD,CA,94541,90D,DUI ALCOHOL/DRUGS,ACSO,11021283,"(37.66655037, -122.10000611)" Logstash conf file  input{  file {    path => "/home/ubuntu/test.csv"    start_position => beginning  } } filter {     csv {     separator => ","    ...
Read more

Kibana 4 Installation and Run as a service in ubuntu

Download and install kibana4 To download kibana 4 wget https://download.elasticsearch.org/kibana/kibana/kibana-4.0.1-linux-x64.tar.gz Extract and Rename kibana tar -xvzf kibana-4.0.1-linux-x64.tar.gz sudo mv kibana-4.0.1-linux-x64 kibna-4 To run kibana *Run bin/kibana on unix, or bin\kibana.bat on Windows. *Visit http://localhost:5601 To set kibana 4 as a service 1. Create a file in /etc/init.d/kibana 2. Add kibana.txt  contents into  file 3 . Give permissions to    sudo chmod 755 /etc/init.d/kibana 4. Update kibna in update-rc.d     sudo update-rc.d kibana 5. To start kibana as a service     sudo service kibana start 6. Disable autostart for a tomcat service     update-rc.d kibana disable Kibana.txt #!/bin/sh #Change kibana path as per your config KIBANA_EXEC="/opt/kibana/bin/kibana" LOG_FILE="/var/log/kibana/log" PID_FILE="/var/run...
Read more