What is a Plugin file?

A Plugin is a component that forms the gateway between a webserver and it's corresponding Application Server. All the requests that comes to the WebServer (eg:- IBM HTTP SERVER) will be routed to WebSphere Application Server with the help of a PLUGIN.

PLUGIN is responsible for filtering and redirecting this requests to the application server and the configuration it uses is called Plugin-cfg.xml. This file basically contains all the information of the WAS destination like the route, server host, cluster information, Virtual Host, Transport Chain settings etc. Correct entries in this file decides the correct passage of requests from IHS server to WAS. So it is extremely important to have the most updated details in this Plugin file. All the features like Load balancing, Clustering heavily depends on the content inside a Plugin-cfg.xml file.

After the deployment of application & WAS environment settings creation, we generate the plugin from WebSphere Console and propogate it to the IHS Server. As a result each request going to IHS, will read this content from plugin-cfg.xml file and route the requests to the WAS.

This is just an introduction to Plugin component, we will discuss detailed analysis of this request flow later in this blog.

Middleware ????

WebSphere application server is a middleware component that basically acts as a middle man between the application code and its backend. Code written in java needs to make use if the run time infrastructure at the back end which provides the information a java code requires. Now the component which enables this necessity of information sharing is called Middleware.

So Middleware basically acts as a ‘middle person’ between the front end and the back end. In technical terms, you can say this as part of business processing, data integration..Etc. But to keep things simple, middleware acts as a manager of the information that are being transmitted from a code to its back end. It determines how effectively a programming code can act upon the data being fetched from the database and it provides the best environment for this data to get processed.

In short we can see the code, we can see the website, but the journey from a code to its corresponding website is determined by how effective your middleware product is.