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Deployment

Hello readers,

My today’s blog is on deployment and it’s different types.

What is Deployment?

In software development, it means delivering software to the client. In other terms, it is the process of installing/upgrading web application on the servers like Tomcat, JBoss.

There are two types of deployments.

Hot deployment

Cold deployment

What is Hot Deployment?

The process of deploying the web app in a running server is called Hot Deployment. In this approach, there is no need to restart the server. All changes take place on ON-THE-FLY.

How we can achieve it into Tomcat server?

We need to specify the autoDeploy attribute of tag to "true". For example, refer to below configuration. Due to below setting now when we copy new WAR into appBase, new changes will get reflected directly without server restart.

<Host name="localhost" appBase="webapps"
  unpackWARs="true" autodeploy="true">
  
  ....
  ....
</Host>

Advantages:

No overhead of stop server => deploy WAR => start the server.

No server downtime. The app is always available.

Good choice of deployment in the test server environment.

Time-saving.

Disadvantages:

The file size keep increasing exponentially. Because files are being used by the server and those are not released by the server.

Example: log files, /tmp directory files.

This is not a good approach for production servers. It will create a memory problem and after certain time app will crash.

What is Cold Deployment?

Cold deployment can be defined as a process that requires a server restart to reflect the changes of application. Cold deployment is slow but stable:

Steps of cold deployment:

Stop running server(Tomcat)

Optionally delete data/, log/, tmp/, work/

Deploy/Redeploy your application(s)

Start Tomcat

Advantages:

No memory issues. We can clear all log files, cache or /tmp files when the server is stopped.

Disadvantage:

It is more time-consuming.