Do I have to use Tomcat to use Essential?

This is a question that we realise potential users of the Essential Project tools are asking. In particular when the architecture team has spent many years trying to get to grips with technology diversity, it can be somewhat embarrassing – or even not an option – to have to go off-piste to use an enterprise architecture management tool!

The simple answer to this question is, however, “no”.

You do not have to use Apache Tomcat to use Essential Architecture Manager.

From the outset, we designed the Essential Architecture Manager software so that it can run on any platform – both operating system and application server – to provide as much flexibility in the prerequisites as possible. This means that Essential can fit into as many existing technology architectures as possible, taking advantage of existing technology platforms wherever possible.

The same question can be posed to the choice of relational database software for multi-user installations. Again, as we can see from the software architecture model, where a range of JDBC-compliant databases can be used, Essential can fit into your existing technology architecture, taking advantage of your standard database platform.

If I don’t have to use Apache Tomcat, what else can I use?

You can use any Java Servlet engine or J2EE application server as the runtime platform for Essential Viewer, which is packaged as a standard Java WAR file. This gives you the freedom to deploy and run Essential Viewer on a range of application servers such as Oracle AS, IBM WebSphere or JBoss.

Since the Essential Project is a free, open-source toolset, we have focussed on application servers and database platforms that are also available free and open-source. The available documentation covers these free platforms as we find that most of our users – certainly the initial stages of using Essential – use these platforms. However, in the spirit of open-source and applying this to our documentation we would welcome any documentation contributions from users who have experience to share about deploying the Essential Viewer WAR to alternative Java application servers.

What about the installer?

The Essential Project takes advantage of a number of other open-source toolkits and the installation process involves adding plugins or components to these other open source EA tools, e.g. Protege and Tomcat. The first releases of Essential did not include an automated installer but we provided detailed documentation for the installation process – including troubleshooting – and this documentation is applicable to other Java application servers.

In order to make the installation process as simple as possible, the automated installer checks the locations of the Protege and Application Server that you specify to help ensure that the Essential components are being installed in the correct places. Although the installer does not assume that Tomcat is being used (despite the messages on the installer windows!), it does assume that the target application server holds its web applications in a folder called ‘webapps’ – which is what Tomcat does.

This means that if the installer cannot find a folder called webapps in the location that you’ve specified for the Application Server, the installer will not proceed.

It is not really practical to cover all the variations of Application Server deployment approaches, so currently a work-around for anyone who is not using Tomcat is to create a ‘webapps’ folder in your Application Server and install the Essential Viewer WAR to there.

Perhaps the other approach is to relax the error-checking in the installer and allow the Essential Viewer WAR to be installed to any folder on the target environment? This places more responsibility on the user of the installer to install the WAR to the correct location but also provides them with more flexibility.

Either way, if you have any problems installing any of the Essential Project components, please contact us. Free support is always available through the forums.

I would be very interested to hear any views on the how to strike this balance in the installer.

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