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Demystifying Architectural Styles. Nikunj Mehta. Architectural Styles. Characterize Structure, i.e. external appearance Supported interactions, i.e. software connectors Topological constraints Various categories Motion of data, e.g. batch sequential, data flow
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Demystifying Architectural Styles Nikunj Mehta
Architectural Styles • Characterize • Structure, i.e. external appearance • Supported interactions, i.e. software connectors • Topological constraints • Various categories • Motion of data, e.g. batch sequential, data flow • Order of computation, e.g. subroutines, objects • Communication centric, e.g. client/server, events • Data centric, e.g. databases, blackboard, hypertext • Layered, e.g. interpreter Demystifying Architectural Styles
Why Research Architectural Styles? • Design patterns are not enough • Styles support higher level reuse • Component based software engineering • Avoiding COTS mismatches • Model based software engineering • Avoiding model clashes • Little is known about • Style similarities • Style primitives • Architectural primitives • Connector composition Demystifying Architectural Styles
Mystical Nature of Styles • Stem from principles of encapsulation, and information hiding • Invisible software connectors are key • Origin of styles - a mystery • How is a style created? • How is a connector created? • Codification of successful approaches • One size fits all? • How do we which styles is appropriate? Demystifying Architectural Styles
We Need… • Style and architectural primitives • Architectural composition techniques • Tool-supported formal model • Separation of behavioral, structural, compositional and interaction concerns • Architectural prototyping framework • Connector composition • Architectural assembly language • Welcome Alfa! Demystifying Architectural Styles
The Alfa Project • Alfa – a bottom-up approach • Architecture needs composition • Assembly language • Constructs and primitives for composition • Fine grain control over semantics • General but simple • Small set for analyzability and conceptual integrity • Style neutral and implementation agnostic • Memories revived? • Assembly mnemonics and machine code • Start small, and then create languages and tools Demystifying Architectural Styles
Composition primitives • Particles • Simplest architectural elements • Portals • Entry/exit points for particles • Jumpers • Interaction ducts • Softwire • Links • Interaction path between particles Demystifying Architectural Styles
Behavioral primitives • Fragment Controller • Locus of functional computation • Transport Controller • Locus of interaction • Portal Controller • Locus of message filtering/tagging Demystifying Architectural Styles
Message Communication container Call Procedural invocation primitive Dispatcher Dispatch messages and calls to controllers Thread Schedule and control execution Queue Buffer for holding messages and calls Semaphore, Monitor, Rendezvous Synchronization Interaction primitives Demystifying Architectural Styles
Architectural framework Compositional Aspects Behavioral Aspects Demystifying Architectural Styles
Composing Client Server Style Demystifying Architectural Styles
Lessons learned • Architecture approaches should be composable • Provide simple primitives that map consistently to implementation • Data centric styles differ at fundamental level from communication centric styles • Choose an architectural style that makes sense • Know which style is good for your context • Know the software connectors required • Create architectural implementation framework Demystifying Architectural Styles