Dennis Smith, David Carney and Ed Morris DEAS Workshop May 21, 2005

1. Interoperability Issues for Autonomic Computing Dennis Smith, David Carney and Ed Morris DEAS Workshop May 21, 2005

2. Context for Interoperability • Most modern systems are usually a heterogeneous collection of custom and commercial products • Integration provided by some third-party technology • Modern systems are seldom expected to function independently • Expected to cooperate with existing systems • The ability to achieve “cooperation” is generally termed "interoperability“ • Elements of these cooperating systems undergo frequent (e.g., upgrades of commercial products) • Thus: boundaries within and between systems beginto blur • Distinction between a "system of systems" and a single, complex, distributed system disappears

3. We know quite a lot about constructing systems from components (over which we may have little or no control). Unplanned, unexpected, emergent behavior here… We know something about composing systems of systems from individual systems (over which we may have little or no control). System “B” We know very little about constructing an interoperable network of systems…the key distinction being that the network is unbounded (or very loosely bounded) and has no single controlling authority. “SYSTEM D” System “A” System “C” Current State of Our Knowledge

4. Autonomic Computing Requires Attention to Interoperability Issues • Selected relevant autonomic characteristics: • Reflexivity: detailed knowledge of a system’s components and their inter-dependencies • Self-configuration: reconfiguring at run-time and adaptive algorithms can benefit from research in interoperability on “emergent algorithms” • Evolving: the evolution of systems relies directly on understanding how to add components and systems to an existing system or system of systems

5. Interoperability Issues That Can Impact Autonomic Systems • Tests to verify interoperability often fail to identify interoperability shortfalls • When interoperability is achieved, it is often difficult to maintain as new versions of constituent systems are released • Planned interoperability between new systems is often scaled back to maintain compatibility with older systems • Strict specification of standards for achieving desired levels of interoperability is often insufficient because organizations constructing compliant standards often interpret them in different ways

6. Principles Required to Address Interoperability for Autonomic Systems- 1 • No clear distinction can be made between Systems and Systems of Systems. • One man’s system-of-systems is another’s system. • The critical factor is less where a boundary might lie and more where control lies • most systems are now created with some components over which the integrator has less than complete control • There will always be new things to integrate into the system.

7. Principles Required to Address Interoperability for Autonomic Systems- 2 • Interoperability problems are independent of domain • Most complex systems in almost every domain are now expected to interact with other complex systems • Solutions cannot rely on complete information • Classic software engineering practice assumes a priori understanding of the system being built, including complete and precise comprehension of assumptions, functionality, services, data and quality attribute needs. • Multiple organizations have multiple—and rarely parallel—sets of expectations about the constituent parts and the entire system of systems

8. Principles Required to Address Interoperability for Autonomic Systems- 3 • No one-time solution Is possible • As a result, new approaches are needed to • vet proposed requirements changes at the system and system-of-systems level • analyze the effect of proposed requirements and structural changes to systems and systems of systems • structure systems and systems of systems to avoid (or at least delay) the effect of changes • verify interoperability expectations to avoid surprises when systems are deployed

9. Principles Required to Address Interoperability for Autonomic Systems- 4 • Networks of interoperability demonstrate emergent properties • Emergent properties are those properties of a whole that are different from, and not predictable from, the cumulative properties of the entities that make up the whole • In very large networks, it is not possible to predict the behavior of the whole network from the properties of individual nodes. • Such networks are composed of large numbers of widely varied components (hosts, routers, links, users, etc.) that interact in complex ways with each other, and whose behavior “emerges” from the complex set of interactions that occur

10. Common Observed Interoperability Problems- 1 • Need for understanding on scope and mechanisms of interoperability • Divisions of responsibility • Many divisions in responsibility, obligation, and management • Potential results of these divisions: • Things will fall through cracks • When problems occur, finger pointing can occur • Requirements • Requirements for interoperability are often ill –defined except to “work together” • Requirements for different components and systems often continue to evolve • Functionality • Not all capabilities of different versions are compatible • Achieving backward compatibility represents a major challenge

11. Common Observed Interoperability Problems- 2 • Processes (development and integration) • There is often some degree of misfit between processes, methods and tools employed by different contributors to the system • Other potential showstopper issues • Scalability • Performance • Security • Testing

12. Selected Emerging Research Areas on Interoperability Issues for Autonomic Computing • Models of interoperability • Evolution of components • Semantic issues • Testing and validation • Migration to net centric services • Impact of joint interoperability and survivability requirements • Characteristics of interoperability • Implications of Service Oriented Architectures