[tomcat] How do I update a Tomcat webapp without restarting the entire service?

I'm new to Tomcat. We have a dev machine with about 5 apps running. Even though it's dev, it's used by our clients pretty heavily during testing.

So say we need to make one small change on one class file. Right now, we have to shutdown Tomcat (affecting the other four apps), delete the WAR file (and web app directory), redeploy the new WAR file and restart Tomcat.

Of course, this upsets a few people because it destroys all logged in sessions for all apps.

Is there a better way to do this? I mean, is there a way to only reload the CLASS that changed instead of everything on the dev machine?

Thanks.

There are multiple easy ways.

1. Just touch web.xml of any webapp.

   touch /usr/share/tomcat/webapps/<WEBAPP-NAME>/WEB-INF/web.xml
   

You can also update a particular jar file in WEB-INF/lib and then touch web.xml, rather than building whole war file and deploying it again.

2. Delete webapps/YOUR_WEB_APP directory, Tomcat will start deploying war within 5 seconds (assuming your war file still exists in webapps folder).

3. Generally overwriting war file with new version gets redeployed by tomcat automatically. If not, you can touch web.xml as explained above.

4. Copy over an already exploded "directory" to your webapps folder

In conf directory of apache tomcat you can find context.xml file. In that edit tag as <Context reloadable="true">. this should solve the issue and you need not restart the server