Type Systems –Lura Cardelli

1. The fundamental purpose of a type system is to prevent th occurrences of execution erros during the running of a program. The most obvious symptom of execution errors is the occurrence of unexpected software faults.

2. A type of a variable is the upper bound of the range. Languages where variables can be given types are typed languages.

3. Judgement: formal assertions about the typing of programs; Type rules: implications between judgements; Derivations: deductions based on type rules.

4. Trapped errors: errors that cause the computation to stop immediately; Untrapped errors: errors that go unnoticed and later cause arbitrary behavior. Safe language is the language where all programs are safe, that is, all of them do not cause untrapped errors to occur.

5. Forbidden errors include all of the untrapped errors, plus a subset of trapped errors. Good behavior languages are languages where all of program fragments will not cause forbidden errors to occur.

6. How a type system is formalized?

(1) to describe the syntax of types (knowledge) and terms (behavior); (2) define the scoping rules; (3) define the semantics as a relation has-value between the terms and their results.

University of Glasgow, Gray, P.

1. “Modeling Context Information in Pervasive Computing Systems” (2002) — Karen Henricksen

The project present a model of context that aims to support design activities associated with context-awareness. The model is mainly concerned with capturing meta-information about context that describes features such as the format or formation processes and acutation (the means by which it can be controlled). The model is informal, being concerned more with supporting the processes associated with the development of context-aware software, including requirements analysis and exploration of design issues, thant with capturing context information in a format that can be queried by applications.

The project include information quality as a type of meta-information in their context model, and describe six quality attributes: coverage, resolution, accuracy, repeatability, frequency and timeliness.

University of Karlsruhe, Schmidt

1. “Modeling Context Information in Pervasive Computing Systems” (2002) — Karen Henricksen

The project provides a layered model of context processing in which sensor output is tranformed into one or more cues, which undergo processing to form an abstract context description comprising a set of values, each associated with a certainty measure tehat estimates the certainty that the value is correct.

GIT – Context Toolkit

Context Toolkit

1. “Modeling Context Information in Pervasive Computing Systems” (2002)– Karen Henricksen

Toolkit is a programming toolkit that assists the developers of context-aware applications by providing abstract components (context widgets, interpreters and aggregators) that can be connected together to gather and process context information from sensors.

IBM – WebSphere Everyplace

WebSphere

1. “Pervasive computing: a paradigm for the 21st century” — Debashis Saha 

The project focuses on applications and middleware that extend its WebSphere software platform.

MS – EasyLiving

EasyLiving

1. “Pervasive computing: a paradigm for the 21st century” — Debashis Saha 

The project is developing an architecture and related technologies for intelligent environments. The project supports research addressing middleware, geometric world modeling, perception, and service description. Key system feartures include computer vision, multiple sensor modalities, automatic and semiautomatic sensor calibration, and device-independent communication and data protocols.

HP – cooltown

Cooltown

1. “Pervasive computing: a paradigm for the 21st century” — Debashis Saha

The project focuses on extending Web technologies, wireless networks, and protable devices to create a virtual bridge between mobile users and physical entities and electronic services.

Cooltown uses URLs for addressing, physical beaconing and sensing of URLs for discovery, and localized web servers for directories to create a location-aware system that supports nomadic users. It leverages Internet connectivity on top of this ingrastructure to support communications services.

2.  “Modeling Context Information in Pervasive Computing Systems” (2002) — Karen Henricksen

The project proposed a web-based model of context in which each entity (person, place or thing) has a corresponding description that can be retrieved via a URL. This model is relatively informal; entity descriptions take the form of web pages, which may be unstructured and intended for human (rather thant application) consumption.

Cambridge – Sentient Computing

Sentient computing

1. “Pervasive computing: a paradigm for the 21st century” (2003)  — Debashis Saha

The project explores user interfaces that employ sensors and resource status data to maintain a world model shared by users and applications.

The world mdoel covers an entire building. Interfaces to programs extend seamlessly throughout the building. Computer desktops follow their owners and reflect real-time updates for object locations. The project has led to some new kinds of applications, like comtext-aware filing systems and smart posters.

2. “Modeling Context Information in Pervasive Computing Systems” (2002) — Karen Henricksen

The model is more formal, and is based on an object-modeling paradigm. A conceptual model of context is constructed using a language based on the ER model, and context information is stored at run-time in a relational database.

Washington – Portolano

Portolano

1. “Pervasive computing: a paradigm for the 21st century” — Debashis Saha 

The project seeks to create a testbed for investigating pervasive computing. The project emphasizes invisible, intent-based computing, which infers users’ intentions via thier actions in the environment and their interactions with everyday objects.

Project devices are highly optimized to particular tasks so that they blend into the world and require little technical knowledge on the users’ part. Portolano proposes an infrastructure based on mobile agents that interact with applications and users. Data-centric routing automatically migrates data among applications on the user’s behalf. Data thus becomes “smart”, and serves as an interaction mechanism within the environment.

CMU-Aura

Aura

1. “Pervasive computing: a paradigm for the 21st century” — Debashis Saha

The project aims to design, implement, deploy, and evaluate a large-scale computing system demonstrating a “personal information aura” that spans wearable, handheld, destop, and infrastructure computers.

Aura is a large umbrella project with many individual research thrusts. Darwin is a intelligent network at Aura’s core. Coda is a distributed file management system that supports nomadic file access, and Odyssey provides OS support for resource adaptation.

Theses products and others are evolving within the Aura project, which empahsizes pervasive middleware and application design.