Hot skills: Java coders get best of both worlds with open source Glassfish and SJSAS

Skills for IT professionals

What is it?

Sun Java System Application Server (SJSAS), the commercial implementation of the Glassfish community project, is moving up from a brash young contender to a serious challenger to established application servers from the likes of Oracle, BEA and IBM.

SJSAS is a core part of the Java Enterprise System, supporting development technologies such as Java Studio Enterprise, Java Studio Creator and Netbeans 6.0 integrated development environment.

Sun Microsystems has the edge when it comes to new Java releases, and Glassfish version 1 - the open source version of SJSAS - was the first Java EE5 application server. Glassfish v1 was strictly a developers' version. Glassfish version 2 and its commercial counterpart SJSAS 9 update 1, released in September, added enterprise-strength features, such as high availability and scalability through clustering and replication.

The commercial and open source versions offer the same core features, but SJSAS comes with services and several optional bundles. Analyst firm Gartner says, "Glassfish is available as a free 'use at your own risk' download. Sun's SJSAS is a certified, supported and indemnified offering available by subscription or as a perpetual licence."

Gartner describes Glassfish and SJSAS as "promising alternatives to the current open source Java EE products", but as yet with "limited industry production experience".

The free downloads and Glassfish community resources and support provide an alternative skills acquisition route to Sun's own, very expensive, training.

Where did it originate?

Project Glassfish was launched in June 2005. Sun donated SJSAS version 8.x to the Glassfish community, hence the disparity in numbering: Glassfish version 1 was SJSAS 9.0.

Oddly, Oracle, one of the application server market leaders, is a major contributor to the project, donating its Toplink Essentials persistence technology. Ericsson supplies the SIP Servlet technology.

What's it for?

The clustering support in SJSAS allows servers to be grouped for scalability and to replicate data in-memory for failover protection and high availability. Application server clusters can be managed from a central console.

The September releases also introduced support for interoperability between web services running on Java or Microsoft Windows. This uses the Project Metro web service stack.

The SJSAS 9.1 optional bundles include a graphical installer, to be introduced to the community version with Glassfish 3, and a high-availability ("99.999%") database as a stronger alternative to the open source memory replication. This database is not yet open sourced, and Sun's developer network site describes its implementation and maintenance costs as "relatively high".

What makes it special?

Sun describes Glassfish as "the standard Java EE reference implementation". Gartner describes "the large Solaris installed base" as another potential strength.

How difficult is it to master?

Sun offers a one-day workshop for people already involved in application design, deployment, administration, or support for £400.

Where is it used?

As always with open source products, it is hard to know how many downloads have resulted in production implementations. There are at least 3,000 users of SJSAS worldwide.

What systems does it run on?

Solaris 9 and 10 on x86 and Sparc, Red Hat and SuSE Enterprise Linux, Windows Server 2000 and 2003, XP and Vista.

Read more on Web software