Understanding Software Connector Compatibilities Using a Connector Taxonomy. Nikunj Mehta Ph. D. Candidate

Transcription

1 Understanding Software Connector Compatibilities Using a Connector Taxonomy Nikunj Mehta Ph. D. Candidate

2 Software Architectures High-level modeling primitives Components, connectors, configurations [SG96] Software connectors To mediate interactions among components To provide auxiliary mechanisms for interaction Impact aggregate system properties Liveness, throughput, dependability, evolvability Support in software architecture techniques Modeling [AG97], middleware support [MMR02] Complementary approaches Middleware (ORB), standards (e.g. COM, J2EE)

3 Towards Richer Connectors Focus on connectors Component scale, complexity requires greater distribution Complexity of interactions a bigger concern than complexity of algorithms Simple connectors Procedure calls, module dependencies, pipes Complex connectors DNS, remote procedure calls, repository access State-of-the-art in software connectors Model arbitrarily complex - implement simple ones

4 Interaction Services (MMP00) Communication Transmission of data Coordination Exchange of control Conversion Transform interactions to remedy heterogeneity Facilitation Streamline interactions for interoperation

5 Classification Framework

6 Connector Taxonomy

7 Hybrid Connectors Real-world situations often require sophisticated connectors E.g. RPC with privacy and integrity Hard to systematically compose hybrid connectors Integration issues Interoperability of connectors Mismatching assumptions about interaction Cause for project failures [GAO95, GB98]

8 Composing Hybrid Connectors First order Does not combine connector types e.g. objectoriented method call Higher order Combine dimensions from different connector types e.g. RPC, SSL Not all combinations of dimensions result in meaningful, or safe connectors Taxonomy provides empirical rules of compatibility between connector dimensions

9 Connector Compatibility Rules Cautions ( ) Certain combination of dimensions required to be used in conjunction are unsafe Requires ( ) Dimensions required to be used in conjunction, no unsafe combinations Restricts ( ) Dimensions may be combined, some combinations are unsafe Prohibits ( ) Dimensions cannot be combined

10 Procedure call Event Data access Stream Linkage Arbitrator Adaptor Distributor Parameters Entry point Invocation Synchronicity Cardinality Accessibility Cardinality Delivery Priority Synchronicity Notification Causality Mode Locality Mode Availability Accessibility Cardinality Delivery Format Directionality Cardinality State Granularity Cardinality Resolution Fault handling Concurrency Transactions Logging Security Scheduling Pooling Invocation Data Presentation Deployment Naming Delivery Routing Procedure call Event Data access Stream Linkage Arbitrator Adaptor Distributor Parameters Entry point Invocation Synchronicity Cardinality Accessibility Cardinality Delivery Priority Synchronicity Notification Causality Mode Locality Mode Availability Accessibility Cardinality Delivery Format Directionality Cardinality State Granularity Cardinality Resolution Fault handling Concurrency Transactions Logging Security Scheduling Pooling Invocation Data Presentation Deployment Naming Delivery Routing

11 Applications/Evaluation Stability of taxonomy Taxonomy applied to architecture of Linux [MMP00] Sparser reflexive sections reflect lack of known incompatibilities Rich constraints indicate greater cohesion and stability Compatibility constraints Rule out potentially unstable connector species Create higher-order connectors using transitive application of constraints

12 Current Status/Future Work Publication N. R. Mehta & N. Medvidovic. Understanding software connector compatibilities using a connector taxonomy, SoDA 02, Bangalore, India ACTiVE Expert knowledge capture tool for connector compatibilities Design guidance using compatibility matrix Alfa Composition of architectural style elements including connectors from architectural primitives (