web programming

Development of the Apache project's Tomcat JSP and Servlet engine continues apace, and again, Wrox has done a good job in swiftly getting a book to market which covers the latest version.

Wrox's earlier book by many of the same authors, 'Professional Apache Tomcat' covered versions 3 and 4. This book no longer contains any material specific to version 3, but has had a major overhaul and concentrates on Tomcat 5, though it's still useful and relevant to administrators working with version 4.1 and up.

Like its predecessor, the book covers the installation and management of Tomcat in great depth on both Unix and Windows. Its Unix coverage is geared towards Linux in favour of any other version of Unix, but in practice there's nothing particularly Linux specific and users of other Unix variants will have no problems following the examples.

As with the previous edition, the first two chapters provide background to the Apache project, J2EE and the evolution of web application technologies from CGI to JSP. Detailed chapters on installation and architecture follow. Only installation of the Tomcat binaries is here though; building Tomcat from source with Ant is not discussed at all (however, Ant is referred to throughout the book, mainly in relation to application building and deployment, and gets an appendix of its own). The architecture description is unchanged from the previous edition, but remains an excellent overview of Tomcat's internal components.

And on to the nuts and bolts. A lot of space is given to the new web-based administration tool (itself a web application handled by Tomcat), but at all points the underlying affects on Tomcat's raw XML configuration files is made clear, so the command line junkies - or those who choose not to enable the Administration Tool at all - are catered for in parallel with the point-and-click brigade. Web application configuration and management is much expanded, now covering Servlet 2.4 descriptors as well as those for 2.3.

Tomcat's HTTP connectors, employed when Tomcat is set up as a stand alone web and application server are described in a single chapter, but new to this book are details of using the SSI and CGI servlets which are new features of Tomcat 4.x and 5.

For non-trivial installations, one would wish to integrate Tomcat with a web server, creating an environment in which the web server delegates dynamic content to Tomcat which otherwise no longer handles HTTP directly. There are a number of protocols available for Tomcat which provide the connection to a web server. As these protocols have stabilised in Tomcat, so the book no longer covers the older, largely deprecated connectors beyond a brief description of each. It then concentrates almost solely on the JK2 implementation of AJP.

This whole area is a lot clearer than it was in the earlier book: a short chapter provides the background and describes the protocols used to connect the web server and Tomcat, followed by a chapter devoted to each of Apache (for both Unix and Windows) and Microsoft's IIS web server using the JK2 connector. I was a little disappointed to find that Sun's web server gets no mention at all, particularly as up-to-date official documentation in relation to it appears to be non-existent. Nonetheless, what's here for Apache and IIS is very good; Apache users get a better deal than their IIS counterparts though - the load balancing and SSL integration sections are far more complete in the IIS chapter.

That completes the first half of the book, and for many uses will provide more than enough information to get a good understanding of Tomcat and a working service. Six more chapters go into great detail about Tomcat's other features. Separate chapters exploring JDBC connectivity, the new JMX features of version 5 and Java class loaders really earns the book its Professional tag. Arguably more useful (in my case at least) are the chapters dedicated to security, clustering for fail-safe operation and embedding Tomcat within an application - absolutely everything is here. The chapter on server load testing proved to be a great help to me just for the inclusion of the use of JMeter, another Apache project which is useful for all manner of web server benchmarking.

Tomcat's documentation is more than adequate for quickly setting up a Tomcat server, but dig much deeper and it quickly becomes difficult to find what you're looking for. Having a book like this with everything to hand makes life a lot easier, and in any case it's worth much more than the official documentation.

Criticisms? I'd like to have seen an appendix or two giving a summary of the main Tomcat configuration files workers2.properties and server.xml; as it is not quite everything is covered and what is spread across different chapters. At the moment I'm working with Sun's web server and Tomcat and it would have been great to have a chapter dedicated to this particular setup, particularly as far as JK2 is concerned.

Wrox had some difficulties last year when its parent company collapsed, but now that Wiley have taken over, it's good to see them back on their feet and continuing to produce books like this, complete with their familiar red covers (...and dodgy author photographs). Highly recommended.

Good book, no fluff..just stuff. Explains diff. between 4.0 and 5.0, gives latest cofig and development tech for 5.0