TAPAS Basic Architecture

From TAPAS Wiki

The TAPAS basic architecture, as illustrated by its object model, is based on generic actors in the nodes of the network that can download manuscripts defining roles to be played. These nodes are network processing components, such as servers, routers and switches, and user terminals, such as telephones, laptops, PCs, PDAs, etc. The model is founded on a theatre metaphor, where actors perform roles according to predefined manuscripts, and a director manages their performance.

A service system consists of service components, which are units related to some well-defined functionality defined by a play. A play consists of several actors playing different roles, each possibly having different requirements on capabilities and status of the executing system. A role-session is a projection of the behaviour of an actor with respect to one of its interacting actors. An actor is a generic object, which will constitute a role figure by behaving according to a manuscript defining the functional behaviour of that particular role in a play. A service component is realised by a role figure based on a role defined by a manuscript. A role figure, however, is realised in an executing environment in a node and is utilising capabilities. A capability is an inherent property of a node. A node may have several capabilities. These capabilities are offered to actors, which constitute role-figures in various plays. The ability to play roles depends on the defined required capability and the matching offered capability in a node where an actor is going to play. Examples of capabilities are processing, storage and communication resources (e.g., CPU, hard disk and transmission channels), standard equipment (e.g., printers and media handling devices), special equipment (e.g., encrypting devices), and data (e.g., user login and access rights).

TAPAS basic architecture has several layers as viewed from the functionality and support platform point of view:

Following is an example, which illustrates the structure of the support functionality. The Actor-environment-execution-module (AEEM) is a process or thread that executes a collection of actors with associated Plug-and-Play Actor Support (PAS). A collection of actors is here one or more actors constituting application role-figures or director role-figures. The TAPAS platform basic functions supported are provided by the procedures: PlayPlugIn, PlayChangesPlugIn, PlayPlugOut, ActorPlugIn, ActorPlugOut, ActorBehaviourPlugIn, ActorChangeBehaviour, ActorBehaviourPlugOut, RoleSessionAction, ChangeActorCapabilities and Subscribe.