By Ian Lumb, Grid Solutions Manager, Platform Computing
In light of this week's first GlobusWorld conference in San Diego, there is much talk about the emerging standard known as the Open Grid Services Architecture (OGSA). Just about everyone who has anything to do with Grid Computing is claiming compliance with this standard. However, if OGSA is still a work in progress, what exactly does OGSA compliance mean?
If you search Google for "OGSA compliance", it returns 139 hits. Among them are the usual suspects - legit pointers to the Global Grid Forum (GGF), Globus Project, Globus Toolkit and various others in a wide variety of languages. The phrase "OGSA compliant" results in better quality Grid hits, and more of them - 449 in this case. What is interesting is that although these phrases are being used liberally, not one page provides a definition of OGSA compliance - not even http://www.globus.org/ogsa.
Standards compliance is very important to Grid solution providers like Platform because they pave the way for interoperability, and provide a yardstick for professionalism in software engineering. As a highly customer-focused company, Platform knows that enterprise customers are bullish on standards compliance and demand that vendors stand behind these claims. The future of Grid computing is dependent on a common set of standards that provide the collaborative context for partners to work together. For those of us truly concerned with delivering against OGSA, there is a pressing need for a working definition of compliance.
Anticipating the Need for a Working Definition of OGSA
Delving into standards requires a certain gastrointestinal fortitude. Fortunately, the GGF's OGSA Working Group has anticipated the need for a working definition.
There are two major pieces to OGSA - core Grid components and a common Grid infrastructure. Core Grid components target functionalities like resource allocation and policy management. Built on top of the infrastructure piece, these components can be combined to build Grid applications and services. The common underpinning is the Open Grid Services Infrastructure or OGSI. OGSI results from Grid-motivated extensions to Web Services and specifies a Grid Service. This Grid Service removes the need for core Grid components to directly reference specific protocols like FTP, HTTP or LDAP. In the pre-OGSA world, this was common practice out of necessity. It handcuffed components to protocols making integration and extension labor intensive.
Today, OGSA compliance can be defined as clients or services that are compliant with the OGSI Grid Service Specification. The OGSI Grid Service Specification Version 1.0 will enter the GGF recommendation track in about one month. This specification is a primary deliverable of the GGF's OGSI Working Group and serves as the foundation for OGSA.
An OGSA-compliant service can be defined as any OGSI-compliant service whose interface has been defined by the GGF OGSA Working Group to be a standard OGSA service interface. Again, the onus is with a Working Group in the GGF to serve as the focal point for defining standard interfaces.
Both of these definitions rely on the continued work of the GGF. OGSI's Grid Service Specification version 1.0 is only entering the recommendation track at the GGF, and the "accepted standards" for OGSI interfaces (OGSA) are still in the hands of the OGSA Working Group. Does this mean OGSA compliance is still a vision for the future?
GT3: Setting the stage for OGSA-Compliant Grid Implementations
This week at GlobusWorld, the Globus Toolkit 3.0 (GT3) release is featuring the first OGSI-compliant implementation of this staple in Grid middleware. True to its lineage, GT3 remains available under a liberal Open Source license - the Globus Toolkit Public License (GTPL). It's the GTPL that permits commercially supported versions of the toolkit such as Platform Globus. Platform Globus is built on the vanilla distribution of the Globus Toolkit from the Globus Project. Platform adds value through enhancements - improved packaging and installation, improved interoperability with Platform LSF - technical support, documentation, and the availability of professional services for Grid planning, deployment and ongoing management.
The alpha-stage public release of GT3 was announced early this week at the inaugural GlobusWorld event. The beta release is anticipated in April, with the official release targeted for June. The Globus Project has also announced the sunset of Version 2.x of the Globus Toolkit by the end of the calendar year.
The highlights of GT3 include:
Familiar Globus components. Grid Resource and Allocation Management (GRAM), GridFTP and Monitoring and Discovery Service (MDS) comprise the core Grid components layer. GT3 also includes some significant additions at this level. One of these is the OGSI-compliant database services contribution from the UK e-Science Grid. The appearance of these new core Grid components is significant: These components validate that GT3 provides a foundation that can be built upon - i.e., the extensibility handcuffs are off.
Various runtime contexts. GT3 provides four choices of Java-based hosting environments - embedded, standalone, J2EE Web container and J2EE EJB container.
Grid security. OGSA security inherits from past successes. SOAP-message security is based on the Grid Security Infrastructure or GSI. The GSI specification is a product of the GGF's Grid Security Infrastructure Working Group. Since Version 2.0, the Globus Toolkit has offered a GSI-compliant implementation of this specification.
It's clear that the GGF has a reputation for turning research into standards. And the Globus Project has a reputation for turning standards into implementations.
At GlobusWorld, Grid solution vendors - Avaki, HP, IBM, Oracle and Platform - and Grid projects - UK e-Science Grid's DAIS and USC/ISI's Virtual Data Toolkit - will reveal their product strategies for the Globus Toolkit and OGSA. Despite the hype, OGSI-compliant GT3 truly is a watershed event. It emphasizes that OGSA is evolving into something real in the near term.
Platform Compliance with OGSA
The Platform take on OGSA is straightforward: Involvement in the process and compliance with the standards. Platform is a GGF sponsor and advocate. Ian Baird, Platform's Chief Business Architect, holds a seat on the GGF board. This means that Platform connects with the daily operations and future directions of the GGF.
Platform participation at the technical level complements the ongoing commitment to GGF governance. GGF sponsors some 40 working and research groups. Nowhere is there is better reflection of the diversity of Grid computing. We've already made ample references to working groups like GSI, OGSA and OGSI. These groups have tightly focused agendas, and a mandate for tangible outcomes like specifications. GGF also includes a number of research groups. In contrast to the working groups, research groups are concerned with emerging areas, and may or may not have tangible deliverables.
Platform participates in those working groups that apply directly to our business. Our approach is to be deeply engaged in a few areas where we can make substantial contributions. We are anticipating significant activity over the course of 2003.
Partnerships also means involvement in OGSA process. At Supercomputing 2002 in November, Platform and the Texas Advanced Computing Center (TACC) of the University of Texas at Austin announced a strategic collaboration. It is clear that some of the Platform-TACC projects will have an OGSA spin. For example, TACC has already integrated Grid middleware from Platform with their Grid Portal Toolkit, which was the showcase of their demonstrations at Supercomputing. As TACC refactors GridPort under OGSA, there will be a need to carry forward this integration.
Summary
As the Grid world is poised to move into commercial computing, standards become critical. With this basis of open standards providing the highest levels of interoperability, widespread Grid adoption is inevitable. Those concerned with standards compliance require a working definition today and a roadmap for the future. OGSA will be an integral achievement of the GGF and the OGSI Grid Service Specification milestone and demonstrates the initial steps towards a complete Grid standards architecture. Platform is committed to a strong partnership with GGF to develop and support OGSA.
Acknowledgements
Thanks to Steve Tuecke of the Globus Project for the compliance definitions.
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