Status of This Document
This specification was published by the Cloud Computing Community Group.
It is not a W3C Standard nor is it on the W3C Standards Track.
Please note that under the
- W3C Community Final Specification Agreement (FSA)
other conditions apply.
Learn more about
W3C Community and Business Groups.
Definitions
- Computation
- Process by which data in some system transforms in some
some way over some period of time
- Node
- Entity performing the computation within some system
- Storage
- The persistent maintenance of information
- Artefact
- information forming either a set of one or more Information
Items or a reference to data in some other
format
- Artefact Space
- A designation of membership of an artefact to
some category or group, identified by IRI
- Region
- A set of artefacts constituting some sub-set
of an artefact space
- Balance
- The property of one or more Nodes in which
the computational or storage load on each is
approximately equalised with that of each of
the Nodes in the set
- Visibility
- Phenomenon in which a Node is able to read
the data constituting an artefact
- Control
- Situation in which an artefact is able to be
exclusively modified by a Node
- Ownership
- Relationship of control between a Node or
one or more artefacts
- Transaction
- The durable, atomic (in the view of some
Node) and reversible transition between different
consistent configurations of the artefacts in
some system
- Model
- A record of the static state and relative
dynamic behaviour of the constituent sub-parts
of some system
- Client
- Originator of a visualisation request
- Consumer
- Entity (either human or user agent) using
("consuming") a cloud service
- Visualisation
- The process of gathering, from multiple artefacts
regions, those artefacts of relevance to some
visualising Client
Requirements
This specification intends to meet the following requirements
- A web browser's view (in the Window Object
Model) [Window] of stored data should be
compatible with functionality specified in
[Web
Storage]
- The capabilities of
computational models should based on that given
in the Object Management Group's XMI
specification [
XMI]
- One or more Nodes should be able, via their
various interconnections, to simulate collective
ownership of one or more artefacts by progressively
relinquishing and taking control of disjoint
regions of some artefact space such that the
storage load on all Nodes are balanced
- on receiving a "visualise" request from some
client within the Region of Control of some Node,
that Node should pass the request on to those
Nodes whose regions of
control are deemed to be "neighbouring" (in some
artefact space) and "behind" the Node in that
client's "visual field", taking a union of each's
returned "visualisable" artefacts, adding those
artefacts located in the Node's own region of
control and returning that set to the requesting
Node, and repeating this procedure until all
artefacts in the client's visual field,
irrespective of controlling Node, have been
rendered to the client
- constraints in the behaviour of groups of
related artefacts should be expressible using
the approach taken by the "assertions" feature
of XML Schemas 1.1 [
Assertions]
- a consumer should begin a request for cloud
work by issuing a multi-cast "service query",
to which listening cloud supplier will
respond with a rule-set describing each's
charging regime, from which the consumer
will select the most appropriate supplier,
to whom the consumer will then issue a "work
request" containing a reference to the
computational model of the work to be
performed and its desired "availability
style" (a style-sheet associating model
electors associated with a property
representing the desired availability
level of that part of the model
corresponding to the selector) to
use for that work
- each Artefact should have one
Node designated to be its owner.
Modifications to artefacts by owning
Nodes should have immediate effect,
while attempted modifications by
non-owning Nodes will engage
transactional semantics conforming
to the Distributed Transaction
Processing specification [
DTP]
- before the ownership is passed
between Nodes, the requesting Node
must first send a request for
ownership change request, passing
its credentials in the request, to
which the owning Node should respond
with an authorisation to its
preferred requester, rejecting
the others, after which ownership
will transfer to the authorised Node
- requests and responses should,
as far as possible, use a SOAP
representation [SOAP]
- artefacts should contain
security credentials ensuring
each's data integrity
- where a
model element represents some type of
ontological artefact, that element
should contain the IRI of the OWL
element [OWL]
representing the artefact
Use Cases
The use cases listed below were created by the Cloud
Computing Community Group to illustrate important
applications for the features of the cloud architecture.
- Use Case 1: A CAD system is equipped with
a "physics engine" which performs continuous analyses,
such as those of - amongst others - acoustic, vibrational
and buckling, of its constituent physical structures, to
determine properties as the inertia and momentum
of each part of the set of structures under analysis
so as to determine the dynamic behaviour, forces and
stresses within those structures. Since the combined
computational requirements of these analyses
are quite high, the load is distributed adaptively
(since the structures, themselves, may change over
time) around the system's computing resources, so
as to keep the system as responsive as possible,
with the greater part of those resources given over
to the geometrically complex parts (which are more
difficult to analyse) of those structures
- Use Case 2: An RDF processor [RDF]
manages a vast collection of triples representing
(amongst others) ontological information: a
collection so large as to overwhelm the storage
capacity of any one machine. The information is
therefore "spread" across enough machines such
that their combined capacity is sufficient to meet
the total storage requirement. The information
stored in each machine is also approximately
"balanced" across all the participating machines
- Use Case 3: a very large XML file
Contains elements representing objects (such as
a "tree" or "house"). Those objects are
represented in multiple levels of detail (such
as "trunk", "branch", "leaf", or "roof", "wall",
"window" and "tile").
these elements are transformed into those constituent
elements that are visualisable by various clients
(on a configurable, per-client basis), enabling such
clients to" visualise" the artefacts built in this
way. These transformed elements may include OWL
ontologies [OWL
] holding knowledge and RIF rule-sets [RIF] able,
when fired, to transform the artefacts based on
certain factors, including the user's actions.
References
- [WINDOW]
- Ian Davis; Maciej Stachowiak Window Object. 7 April 2006. W3C Working Draft. URL: http://www.w3.org/TR/window/
- [STORAGE]
- Ian Hickson Web Storage. 9 April 2013. W3C Proposed Recommendation. URL: http://www.w3.org/TR/webstorage/
- [DTP]
- Distributed Transaction Processing December 1991. X/open Group Technical Standard. URL: http://pubs.opengroup.org/onlinepubs/009680699/toc.pdf
- [ASSERTIONS]
- Shudi Gao; C. M. Sperberg-McQueen XML Schema Assertions. 19 January 2012. W3C Proposed Recommendation. URL: http://www.w3.org/TR/2012/PR-xmlschema11-1-20120119/#cAssertions
- [XMI]
- XML Schema MOF 2 XML Mapping. 8 October 2011. Object Management Group Specification. URL: http://www.omg.org/spec/XMI/2.4.1/PDF
- [RIF]
- Michael Kifer; Harold Boley RIF Overview 5 Febrary 2013. W3C Recommendation. URL: http://www.w3.org/TR/rif-overview/
- [SOAP]
- Nilo Mitra; Yves Lafon Simple Object Access Protocol. 27 April 2007. W3C Recommendation. URL: http://www.w3.org/TR/soap12-part0/
- [OWL]
- Nilo Mitra; Yves Lafon OWL 2 Web Ontology Language
Document Overview. 11 December 2012. W3C Recommendation. URL: http://www.w3.org/TR/owl2-overview/
- [RDF]
- Frank Manola; Frank Manola RDF Primer. 10 February 2004 W3C Recommendation. URL: http://www.w3.org/TR/rdf-primer/