Annals and a Perspective of Architectural Styles and Architectural Patterns within the Context of large Complex Web-Based Systems

ion of recurring structural & behavior characteristics within a set of different architectures – the concept of commonly-recognized “architecture styles“ [Shaw-Clements-1997] One of the most important aspects of software architecture Nomenclature inspired by building architecture (Roman, Gothic, Baroque, etc.) Recurring commonality in organization and behavior – patterns and idioms As a result, often used interchangeably with the term “architectural patterns”, although I actually believe there is a significant difference between these two concepts (to be discussed...) © 2006 Mark M. Davydov 12 Architecture Styles (continued) Initial usage was focused on classification of systems: Generalized classification of systems [Booch-1996] user-centric -focusing on human-machine interactions and manipulation of the objects that define a problem domain data-centric -focusing on the persistent objects that describe a problem domain computation-centric -focusing on the transformation of both types of objects that define and describe a problem domain. Widely known (and commonly referenced) examples: Data-centered Data flow –oriented Client-server © 2006 Mark M. Davydov 13 “Architecture is the will of an epoch translated into space“ -Ludwig Mies van der Rohe, Renowned German born American architect, 1886-1969 “The will” is communicated via preservation of architecture styles in different concrete architectures! A description of a style is a way of providing an architectural context; a mean for identifying and casting all the necessary elements worth preserving in different concrete architectures Importance of Architecture Styles © 2006 Mark M. Davydov 14 1. The primary basis for casting aspects of reuse 2. Essential mechanism to draw the attention of the development community to what must be reused from the architecture perspective 3. An important resource and a placeholder for rigorous descriptions and references Importance of Architecture Styles (continued) © 2006 Mark M. Davydov 15 Depicts externally visible properties of a class of architectures: Aesthetics --mostly means the "look and feel" (translating directly from aesthetics in the world of buildings) – UI, usability (easiness), etc. Fit-to-purpose --mostly means how is it easy, difficult, or even impossible to deliver the desired functionality to the end-user Qualities --performance, security, maintainability, etc.-in other words, what are the parameters around the critical behavioral and structural aspects achievable within a style What Does It Illustrate? © 2006 Mark M. Davydov 16 Structural elements – components and connections among components Constraints defining particular specifics around the usage of structural elements Semantic models – defining the overall taxonomy and its vocabulary for analyzing properties of a style and its constituent parts Elements of a Style © 2006 Mark M. Davydov 17 Significantly different from design patterns, as for example, presented in [Gamma-Helm-Johnson-Vlissides-1994] A primary mechanism of “embodying” style properties Patterns convey a style A certain, similar way of ensuring pragmatism (“Implementability”) of an architectural style M:m relationship between styles and patterns Architecture Patterns