A web application bundle (WAB) is a bundle that contains a web application and that can be deployed in an OSGi container. A WAB is an OSGi bundle version of a web application archive (WAR) file.
WABs are defined in the OSGi Service Platform Release 4 Version 4.2 Enterprise Specification.
You use a WAB in an OSGi application in much the same way that you use a WAR file in a Java™ enterprise application. For example, you use a WAB to host servlets, static content, or JavaServer Pages (JSPs) as part of your application.
A WAB contains OSGi metadata, for example a manifest header, META-INF/MANIFEST.MF, so that you can use the features that OSGi Applications support provides. For example, you do not need to package dependencies inside a WAB.
When you convert an enterprise application that contains only WAR files to an enterprise bundle archive (EBA) file and then import the EBA file as an asset, the WAR files are automatically converted to WABs.