How do I update a Tomcat webapp without restarting the entire service

Question

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

User · Answer

There are multiple easy ways    Just touch web xml of any webapp    touch  usr share tomcat webapps  lt WEBAPP-NAME gt  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    Delete webapps YOUR WEB APP directory  Tomcat will start deploying war within 5 seconds  assuming your war file still exists in webapps folder   Generally overwriting war file with new version gets redeployed by tomcat automatically  If not  you can touch web xml as explained above  Copy over an already exploded  directory  to your webapps folder

User · Answer

Have you tried to use Tomcat s Manager application   It allows you to undeploy   deploy war files with out shutting Tomcat down   If you don t want to use the Manager application  you can also delete the war file from the webapps directory  Tomcat will undeploy the application after a short period of time   You can then copy a war file back into the directory  and Tomcat will deploy the war file     If you are running Tomcat on Windows  you may need to configure your Context to not lock various files   If you absolutely can t have any downtime  you may want to look at Tomcat 7 s Parallel deployments  You may deploy multiple versions of a web application with the same context path at the same time  The rules used to match requests to a context version are as follows    If no session information is present in the request  use the latest version  If session information is present in the request  check the session manager of each version for a matching session and if one is found  use that version  If session information is present in the request but no matching session can be found  use the latest version

User · Answer

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

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

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