This figure shows the relative relationship of the components of Java Enterprise System. In general, components provide support to other components above them in the figure. The components are organized according to Application Services (at the top of the figure), Middleware Services (the next group down), and Platform Services (at the bottom of the figure).
Application Services contains two levels. Level one, the top level, represents Integration services. Level two, the next level down, represents User Collaboration services. Portal Server is shown on level one, Integration services. Messaging Server, Instant Messaging, and Calendar Server are shown on level two, User Collaboration services.
Middleware Services contains four levels. Level one, the top level, represents Security and Policy services. Level two, the next level down, represents Runtime services. Level three represents Messaging services. Level four represents Persistence services. Access Manager is shown on level one, Security and Policy services. Web Server spans levels two and three (Runtime services and Messaging services). Application Server spans levels two, three, and four (Runtime services, Messaging services, and Persistence services). Message Queue is shown on level three, Messaging services. Directory Server is shown on level four, Persistence services.
Platform Services contains two levels. Level one, the top level, represents Network services. Level two, the bottom level, represents Operating System Platform services. The figure shows four operating systems with each operating system spanning both levels. The four operating systems are Solaris, Windows, Linux, and HP-UX.