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GT4: There is something for everybody

At the time this column was written, Globus Toolkit™ version 4.0 (hereafter referred to as "GT4") is scheduled for official release in April 2005. The GT4 release cycle has consumed more than a year of effort from the Globus Toolkit development team, a collaboration of open source developers that includes employees of the core member organizations of the Globus Alliance as well as numerous individuals from other organizations. After several schedule "slips," a reasonable question you may ask is, "What took them so long, and what's in it for me?"

At the highest level, the changes between GT4 and GT3.2 fall into four broad categories:

While most of the written information about GT4 has focused on new features, some of the most profound changes in the GT4 are actually in the other areas. In this column, we describe these changes and their significance for you, the user.

This column represents the Globus Toolkit development team's understanding of what we have done in GT4 over the past year. Early GT4 users have confirmed much of what is described here, but independent reviews are yet to be written, and we look forward with great interest to hearing what the broader community will have to say about this latest edition of the Globus Toolkit.

User Experience Improvements

Without diminishing GT4's exciting new capabilities (which we describe in later sections), the improved user experience is probably the most profound change from previous versions. Intrepid users of the Globus Toolkit 1.0 series were accustomed to research software that would never see use in business or beyond narrow fields in science and engineering. The user community has since broadened and includes less adventurous people from many walks of life, leading to increased expectations for usability. Until now, the toolkit has not kept pace with these rising expectations, leading to an overall sense that the Globus Toolkit is hard to use.

GT4 system administrators and users will experience two major improvements and will likely benefit from a third improvement without realizing it.

The first major improvement is that the documentation has been completely overhauled and significantly expanded, providing users with more consistency in the quality and content of documentation across all toolkit components and considerably more documentation in general. The team took a top-down approach to defining the documentation requirements for the release. Required documentation elements (e.g., "Key Concepts") are provided for each component and for the toolkit as a whole. Other required sections include those on backward compatibility, tested platforms, a developer guide, a system administrator guide, and a user guide. This consistency across components has already been cited by early users as an important element in making the documentation more usable.

The development team has devoted much effort to documenting the GT4 code and its capabilities, thanks in large part to funding from IBM and the National Science Foundation (NSF)'s Middleware Initiative (NMI). Quantitatively, the GT4 documentation is more than double the size of previous releases. Qualitatively, the consistency improvements make it far easier to find the answer to a given question.

The second major improvement is a streamlined installation mechanism. The new installer allows users and administrators to pick the parts of the Toolkit they need installed; it then skips the other components, avoiding unnecessary configuration and administration tasks. The automatic system configuration tools, autoconf, have been updated to the latest public releases so that more platforms are covered. If something stops a build from completing, restarting is much easier now.

Because the Globus Toolkit is used on a wide variety of systems, some quite exotic, we continue to solicit information from the user community about how to build the software on unusual systems. NMI's distributed software build system has greatly expanded the range of systems on which we test code during development.

The third major improvement--which users will benefit from without realizing it--is in how the development team tests the Globus Toolkit. Following a test coverage analysis, the development team added hundreds of new tests that are run automatically during development and prior to releases. These tests are run on a variety of popular hardware/OS platforms. Automated testing has enabled the team to find and fix many more bugs prior to release.

The team has also built testbeds for robustness (how well the software stands up to continuous use) and performance (how efficiently the software performs). All of this testing has yielded significantly more pre-release bug fixes, more performance enhancements, more documentation improvements, and, in general, better software. The development team is not the only group testing GT4. The first public "preview" release of the GT4 Web services code was in July 2004. Subsequent preview releases in August, October, December, and January added more toolkit components. These preview releases mean that when you start work with the April GT4 release, you will have been preceded by hundreds of early users who have already identified problems that the development team fixed prior to the official release.

Functionality Changes

The purpose of the Globus Toolkit is to provide useful functionality for Grid system and application builders. While the user experience improvements mentioned earlier make this functionality easier to access, in the end it is capabilities that make the Globus Toolkit useful.

The non-Web services software in previous versions (GT2.4 through GT3.2) is still present in GT4. This software predates the Grid community's embrace of the Web services framework; but since many production Grids still use these components, we continue to provide limited support for them. Specifically, GT4 provides bug fixes and some improvements in documentation. The Globus Toolkit development team routinely tests the non-Web services components prior to release to ensure that they continue to work as expected. We expect to demonstrate during 2005 that the Web services components provide superior performance and functionality, encouraging migration.

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