Parallel Deployment

Ask the Experts : Tomcat 7 and Parallel Deployment

We are trying to deploy 2 versions of the same application on Tomcat 7 to test its parallel deployment features for our application.

Not meeting with success, I was looking for  a definitive guide for parallel deployment on Tomcat 7.


Our application is a JSP based application but we can have changes often.

asked by csaoin


The definitive reference for parallel deployment comes directly from the Apache Software Foundation:

Additionally, Mark Thomas wrote a summary article explaining how this feature works on the Context Container and across clusters:

answered by SpringSource on January 6, 2012 07:13 AM

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Developers, Operations | Parallel Deployment, Tomcat 7, Tomcat Configuration

Blog : Year in Review 2011

posted by Stacey Schneider on January 4, 2012 07:31 AM

2011 has been a great year for the Tomcat Expert community. After almost 2 years of operating, the Tomcat Expert has hit its stride, unloading an array of new information, as well as keeping you up to date with the newest releases for Apache Tomcat 6 and Apache Tomcat 7. With the addition of two new Tomcat Expert Contributors, (Channing Benson and Daniel Mikusa), the Tomcat Expert community continues to build on its reputation for being the leading source for fresh perspectives and new information on how to best leverage Apache Tomcat in the enterprise.

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Developers, Executives | Cross-site Scripting, Java Development, Parallel Deployment

Blog : Parallel Deployment with Apache Tomcat 7

posted by mthomas on May 31, 2011 07:44 AM

Upgrading web applications can be very expensive if your storefront is the web. Weekend maintenance windows, or downtime in general can give an entire company heartburn. Survey data shows that web application downtime can cost some companies up to $72,000 per minute. Yet the cost of not constantly rolling out new features and bug fixes can equally penalize a company in the competitive online markets today.

Previously, to upgrade an application on Tomcat and avoid downtime, system administrators would have to set up multiple instances of Tomcat and do some very clever stuff with load balancers. This equals extra hardware costs as a permanent part of the company’s infrastructure.

Now with the advent of parallel deployment in Tomcat 7, you can have multiple versions of the same application installed at the same time on a single server. Users with active sessions can continue to use the old application and new users will be routed to the new version. This way, no user sessions will be interrupted, and the old application can gracefully phase out.

Setting Up Parallel Deployment

Parallel deployment is a function of the Context Container. The Context element represents a web application, which in turn specifies the context path to a particular Web Application Archive (WAR) file that is the application logic. Parallel deployment allows you to deploy multiple versions of a web application with the same context path concurrently. When choosing what version of the application for any given request, Tomcat will:

  1. Route new requests to the latest version, so new sessions go to the new application.
  2. If session information is in the request, check the session manager for a matching version, so existing sessions will go to the original application for the request.
  3. If session information is in the request, but the corresponding application is no longer present, it will route to the latest version.

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Operations | Parallel Deployment, Tomcat 7, Tomcat Admin

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