Foreword
The need to keep systems and networks running 24 hours a day, seven days a week has never been greater, as these systems form some of the essential fabric of society ranging from business to social media. Keeping these systems running in the presence of hardware and software failures is defined as service availability. In some areas of networking, such as telecommunications, it has formed an essential requirement for almost 100 years; it is part of why traditional plain old telephone service (POTS) would still be available when power went out. With the advent of the Internet, service availability requirements are increasingly being demanded in the marketplace, not necessarily due to regulatory requirements, as was the case with telephone networks, but due to business requirements and pressures from the marketplace. Of course, it's not just communications where service availability is important, many other industries such as aerospace and defense have similar requirements. Imagine the impact of a loss of control during missile flight, for example.
After the Internet bubble of the late 1990s, and an almost global deregulation of the telecommunications market, it was increasingly recognized that the high cost of development for proprietary hardware and software systems was no longer viable. The future would increasingly be based on commercial off-the-shelf (COTS) systems, where time to market for new services, outweighs the elegance of proprietary hardware and software systems. High availability middleware, which forms a core aspect of delivering service availability, was one of these complex components. Traditionally viewed as high value and differentiating, in this new environment of time to market service emphasis, where rapid application development, adaptation, and integration are key, proprietary middleware is both time consuming to develop and costly to maintain.
The Service Availability Forum (SA Forum) was established in 2001 to help realize the vision of accelerating the implementation and deployment of service available systems, through establishing a set of open specifications which would define the boundaries between hardware and middleware and between the middleware and the application layer. At the time, concepts which are generally accepted today, such as a layered approach to building systems, the use of off-the-shelf hardware and software, and defacto standards developed through open source, were in their relative infancy.
The Founders of the SA Forum, Force Computers, GoAhead Software, HP, IBM, Intel, Motorola, Nokia, and Radisys all recognized that in 2001 the world was changing. They understood that redundancy and service availability would spread downstream from the traditional high end applications, such as telecommunications and that the key to success was a robust ecosystem built around a set of open specifications for service availability. This would allow applications to run on multiple platforms, with different hardware and operating systems, and enable rapid and easy integration of multiple applications onto a single platform, realizing the vision of rapid development to meet the demands of new services in the marketplace. None of what was envisioned precluded the continued development of proprietary systems, but the concepts were clearly aimed at the increased use of COTS hardware and software with a view accelerating the interoperation between components.
Although it has changed over time, as the organization and the market has evolved, the current mission statement of the SA Forum characterizes the objectives set out in 2001.
The Service Availability Forum enables the creation and deployment of highly available, mission critical services by promoting the development of an ecosystem and publishing a comprehensive set of open specifications. A consortium of industry-leading companies, the SA Forum maintains ‘There is no Upside to Downtime.’
It is always a challenge to create an industry organization when so much investment in proprietary technology already exists. On the one hand, there needs to be a willingness to bring some of this expertise and possibly intellectual property to the table, to serve as a basis for creating the specifications. This has to be tempered with the fear that someone will contribute intellectual property and later aggressively seek to assert patent rights. To avoid issues in this area, the SA Forum was established as a not-for-profit organization and a key aspect of the bylaws was that all members agreed to license any intellectual property to any other members on fair and reasonable terms. Since the SA Forum was dealing primarily in software application programming interfaces around an underlying conceptual architecture, the assertion of patents is quite difficult, but in any event, the Forum has always operated on a cooperative model, with everyone seeking to promote the common good and to address differences within the technical working groups. To further control the objective of a common goal, the SA Forum established three levels of membership, promoters, contributors, and adopters. An academic (associate) membership level was added at later date, and the status of adopter was conferred on anyone with an implementation and use of the specifications in a product.
Promoters were the highest level, and only promoters could be on the board of directors. They were the founders of the organization, and hence the main initial contributors. To avoid predatory actions by other companies, additional promoters could be added only by a unanimous vote of all the promoters. While this may seem overly restrictive, it has worked well in practice, and companies who have demonstrated commitment and who have contributed to the Forum have been offered promoter status.
In order to participate in SA Forum work groups and contribute to the specifications, companies had to be contributor members. This proved to be the workhorse membership level for the organization and many valuable contributions came from this group of members.
The adopter members have generally been companies with interest in supporting the SA Forum's work, or who have developed products that have incorporated some aspect of the SA Forum's specifications.
The cooperative nature of the SA Forum has led to the development of a robust set of specifications for service availability. Indeed, that is what this book is all about, the concepts and use of the SA Forum specifications.
The first tentative steps after the formation in 2001 were white papers on the then new concepts of service availability and a layered architecture approach. These were followed by the initial specifications focused on the hardware platform interface (HPI), which has gone through a number of revisions and enhancements. The most recent release of the HPI specification includes provisions for firmware upgrades and hardware diagnostics.
Work on the more challenging application interface specification (AIS), which address the interfaces to applications, management layers, and overall control of the availability aspects of a distributed system. Early work focused on what has come to be known as the utility services, the fundamental services necessary to create a service available system, cluster concepts, checkpointing, messaging, and so on. By the 2005–2006 timeframe, the Forum was ready to address overall system concepts, such as defining the framework and policy models for managing availability. This resulted in the Availability Management Framework (AMF) and the Information Model Management (IMM). These critical services provide both the flexibility to architect a system to meet application requirements, but also a common mechanism for managing availability, with extensibility to manage applications themselves if desired. This complex work really created the core of the SA Forum AIS and it is in many ways a remarkable piece of work. More recent developments have included the Software Management Framework (SMF) to enable seamless upgrading (and downgrade if necessary) campaigns for systems, demonstrating the true idea of service availability, and platform management (PLM), which enables a coherent abstraction of a system. This encompasses complex hardware designs with computer boards equipped with mezzanine cards, which are themselves compute engines, and enables modern virtual machine architectures to be embraced by the SA Forum system model. This in turn enables the SA Forum specifications to become an essential part of cloud computing concepts.
The SA Forum itself has been responsible for the genesis of other industry organizations. It was recognized that the scope of the SA Forum was insufficient to meet the objective of the wide-spread adoption of off-the-shelf technology and the cooperation between the component layers of the solution. By its very charter, the SA Forum was focused on service availability and middleware. An outgrowth of the Forum was the creation in 2007 of the SCOPE Alliance.
The SCOPE Alliance was founded by Alcatel-Lucent, Ericsson, Motorola, NEC, Nokia, and Siemens. It is a telecom driven initiative which now includes many leading network equipment providers, hardware, and software companies, with the mission to enable and promote a vibrant carrier grade base platform (CGBP) ecosystem for use in telecom network element product development. The SCOPE members believe that a rich ecosystem of COTS and free open source software (FOSS) communities provide building blocks for the network equipment manufacturers to adopt, accelerating their time to market and better serving the service provider marketplace.
To accomplish these goals, SCOPE has created a reference architecture which has been used to publish profiles that define how off-the-shelf technologies can be adopted for various application and platform requirements. These profiles also identify where gaps exist between the various layers of CGBP technology. A core component of the CGBP is service availability middleware, based on SA Forum specifications.
Creating specifications is a complex and intellectually challenging task. This is an accomplishment in and of itself. However, the success of the SA Forum and its specifications is really measured by their adoption in the marketplace and their use in systems in the field. Over the years, there have been a number of implementations of the specifications. When the Forum was founded, and the use of open source software was in its infancy, it was foreseen that the specifications would enable multiple implementations and the portability would be accomplished at the application programming interface (API) layer. From 2006 onwards, the Forum had various initiatives aimed at demonstrating portability. Multiple companies did indeed implement some or part of the specifications to varying degrees. These implementations ranged from selected services to complete implementations of the specifications.
On the hardware side, most major hardware vendors have adopted the HPI specification. There are both proprietary, commercial implementations and an open source solution, OpenHPI, available in the marketplace. With the broad adoption of HPI, this can be very much considered a success in the marketplace.
AIS is much more complex and a range of proprietary and open source solutions have appeared in the marketplace since the mid-2000s. These have had various levels of implementation relative to the specifications discussed in this book, and they have included internal development by network equipment manufacturers, proprietary commercial products, and open source solutions. OpenAIS is an open source solution dating from around 2005 and it has been used extensively for clustering in the Linux community. The most complete implementation of the AIS is the OpenSAF project, this is a focus for many adopters of the SA Forum AIS moving forward, with rollout commitments from major equipment manufacturers and a vibrant ecosystem.
Many people, from a wide variety of companies, have contributed to the SA Forum specifications, and their effort and foresight have led to a framework that is now being implemented, adopted, and deployed. The current focus is on expanding the use cases for the SA Forum specifications and demonstrating that they address a broad range of applications. This goes beyond the traditional five and six ‘9's’ of the telecom world and the mission critical requirements of aerospace and defense, to the realms of the Enterprise and the emerging cloud computing environment.
Timo Jokiaho
Chairman of the SCOPE Alliance, 2011, President of the SA Forum, 2003
John Fryer
President of the SA Forum, 2011