Occasionally connected computing (OCC) is a term used in
computing for an architecture or framework which permits running some aspects of a web application when not connected to the Internet. This is sometimes a feature of a
Rich Internet application (RIA).
Software architecture
Occasionally connected computing is a
software architecture based on the idea that an end user should be able to continue working with an internet application even when temporarily disconnected or when a wireless connection fails or is otherwise unavailable. OCC has been seen as one aspect of 'pervasive computing'. In the past, audio and visual telephony no longer functioned when a connection was lost. In an OCC architecture, tasks continue and update a central data store when a connection is restored.
Client-side persistent data Client-side persistent data or CSPD is a term used in computing for storing data required by web applications to complete internet tasks on the client-side as needed rather than exclusively on the server. As a framework it is one solution to the nee ...
(CSPD), while not permanent data as in a central data store, is a common implementation of an OCC framework on non-handheld devices such as personal and laptop computers. As the local data stored on PDAs commonly exceeds several Gigabytes, OCC becomes more viable for handheld devices.
OCC frameworks and implementations
In the case of the
Curl
cURL (pronounced like "curl", UK: , US: ) is a computer software project providing a library (libcurl) and command-line tool (curl) for transferring data using various network protocols. The name stands for "Client URL".
History
cURL was fi ...
language an alternate
URI Uri may refer to:
Places
* Canton of Uri, a canton in Switzerland
* Úri, a village and commune in Hungary
* Uri, Iran, a village in East Azerbaijan Province
* Uri, Jammu and Kashmir, a town in India
* Uri (island), an island off Malakula Islan ...
scheme is used to identify a resource which is to be used for OCC. Where a normal
HTTP URL
A Uniform Resource Locator (URL), colloquially termed as a web address, is a reference to a web resource that specifies its location on a computer network and a mechanism for retrieving it. A URL is a specific type of Uniform Resource Identifie ...
might be
an OCC URI could be
Such a URI
redirects to the web when connected and to the local store when disconnected.
The
Smalltalk
Smalltalk is an object-oriented, dynamically typed reflective programming language. It was designed and created in part for educational use, specifically for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by Alan Ka ...
language is a special case because of the ability to save the
bytecode
Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (norma ...
image at
run time.
The possibilities using the REBOL 2.x runtime environment lie somewhere between Smalltalk and Curl 5.0 but may be extended with the release of REBOL 3.0 which is projected for late 2008 (a public alpha began in Jan 2008.)
See also
*
Curl (programming language) and the Surge RTE for OCC
*
REBOL as an OCC platform
*
Seaside for Smalltalk thinner client for OCC
*
Rich Internet application (RIA)
*
Ubiquitous computing
*
HTTP as a stateless protocol
*
REST which is a computing architecture style which eschews CSPD
References
{{reflist
External links
Adobe whitepaperCurlas a language designed with CSPD for OCC
model of 'both-sides' computing
on OCC
Occasionally Connected Systems Architecture – a blog post by Udi Dahan
Software architecture