A Survey on Programming Model

• Context Toolkit

• Gaia

• ETC (of Equator Project)

• Tentaculus

Context Toolkit

• Anind Dey, Gregory Abowd, Georgia Tech/CMU

• Widget– Widgets encapsulate information about a single piece

of context, such as location or activity. Uniform interface; support both poll and subscription.

• Aggregator– Meta-widgets. Capable of aggregating context inform

ation of real world entities; acting as a gateway between applications and elementary widgets.

• Interpreter– Abstract or interpret low-level context information into

higher level information, such as identity, location and sound level.

Context Toolkit: More Details

• Common communication mechanism (XML over HTTP)

• Runs independently of any applications

• The goal: – provide a toolkit that makes it easier for

application developers to use context. Enable developers to add context to applications that were not context-aware

Context Toolkit: In his own word

• The services of the Context Toolkit are: – encapsulation of sensors – access to context data through a network API – abstraction of context data through

interpreters – sharing of context data through a distributed

infrastructure – storage of context data, including history – basic access control for privacy protection

Gaia• Anand Ranganathan, Roy H. Campbell, UIUC

• Modularized middleware OS – Unified Object Bus, – Kernel

• Application Model (MPACC)– Model (data/operation interface of application), – Presentation (presented actuation), – Adapter (data format converter), – Controller (rules), – Coordinator (configuration)

• Active Space Coordination (script language LuaOrb)

Gaia: More Details

• Components integrated using CORBA

• Scripting language LauOrb used to configure and coordinate applications and OS components with high-level scripting language, and connect the available components in order to compose new services and applications

ECT (Equip Component Toolkit)

• Chris Greenhalgh, Nottingham University, UK

• Component based (proxy), – Property (attribute name - value pair based),– Connection(wired),

• Container (component manager), • Installation (application),

• Tools (graph editor, capability browser, display editor, physical configuration editor, scripter),

ECT: More Details• A more distributed-database-like approach• Details in data propagation is not described in th

e document, possibly following idea similar to associations in database

• Possible use of scripting to create/provide more complex computation and processing capabilities

• A sourceforge open source project• Container/Capability browser and graph editor

ECT: In his own word• EQUIP aims to:

– provide a common run-time infrastructure able address multiple application and deployment domains, including (but not limited to) application integration, real-time 3D graphics, wireless networked systems and heterogeneous platforms;

– support easy interoperation between Java and C++, with cross-language and cross-platform type definitions (using a subset of CORBA IDL) and serialisation formats, and a number of services and facilities implemented natively in both languages;

– support easy extensibility, including run-time class loading in both Java and C++ (using Bamboo [Bamboo]).

• The core of EQUIP is the shared data service "equip_data". This supports pattern-based query operations and query-driven replication inspired by tuple-spaces. It seeks to combine this with ownership-oriented data publishing and updating primitives based on work with collaborative virtual environments. This allows significantly better performance and more flexible data replication for data publishing applications than is possible with pure tuple-spaces.

• In order to make EQUIP-based systems easier to author, deploy and manage we are developing an equip-based component infrastructure (ECT).

Tentaculus• Tentaculus independent living AB (Swedish)

• A list of instructions– Rules based– composed of stimulus/responses with conditions– Event-action-condition

• Flexible and Easy to Use• The adaptation does not require any program

ming skill.

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