Web 2.0 Patterns

Service-Oriented Architecture (SOA)
SOA (defined by the OASIS Reference Model for SOA#) is an architectural paradigm,
a way of architecting a framework for matching needs and capabilities. A
key feature of SOA is support for integrating services that are owned and managed
independently. SOA is a core pattern underlying Web 2.0, and several other patterns
(such as the Mashup pattern and the Software as a Service pattern) rely on it.
An application server offering a SOAP endpoint where consumers can invoke a
service to get a stock quote is a classic example of this pattern.
Software as a Service (SaaS)
SaaS delivers computational functionality to users without them having to persist
the entire application or system on their computers. It applies SOA to the realm of
software, shifting away from the older model of locally installed, self-contained
software. SaaS has evolved largely from the advent of web-aware applications. The
website at http://createpdf.adobe.com is a good example of Software as a Service
because you can use it to turn an HTML document into a PDF document without
having to install any software on your local system. This example is also a specialized
type of SOA. The ultimate expression of this pattern could be virtualization,
the core pattern behind cloud computing.
Participation-Collaboration
The Participation-Collaboration pattern focuses on self-organizing communities
and social interactions among Web 2.0 participants. It embraces reuse of content,
fractional updates or contributions to collective works, the constant beta, trusting
your users, and making the user a core part of the architecture and model for Web
2.0. Wikipedia is perhaps one of the most cited examples of this pattern, as many
people contribute to it. This is also known as harnessing collective intelligence.
Asynchronous Particle Update
This is the core pattern behind Asynchronous JavaScript and XML (AJAX), yet it
can also be implemented in other technologies. Rather than forcing a complete
object (page view) update, a smaller part of the whole can be updated asynchronously.
This pattern has several variations that could trigger such an update, including
timeouts, user activity, changes in state, and preset parameters. These
triggers can happen on a server or a client, or in some other locale, such as in cloud
computing.
Mashup
The Mashup pattern relies on services (see SOA), aggregating content or computational
resources from multiple sources, and mixing them together to create
something new. Commonly, in the resulting view two or more applications appear
to be working together. An example of a mashup is a Google map with financial
data overlaid on it.
Rich User Experience (RUE)
Synonymous with a Rich Internet Application (RIA), a RUE is a replication of the
complete, real-world interaction between two entities, rather than some part of
that interaction. The RUE pattern combines several aspects, including visual presentation,
contextually relevant information, and applications that are modeled to
understand the complete scope of possible interactions between users and software.
An offline example might be a conversation with an employee at a travel
agency, wherein each party learns from and reacts to the other; in contrast, picking
up a brochure from a travel agency to study on your own does not constitute a RUE.
The Synchronized Web
In this pattern, multiple applications or users share the same state or view of the
same state. Online video gamers commonly use this pattern (to be able to play
games together online), but it has evolved far beyond such applications. It is an
essential pattern that supports multiple forms of interaction, including request/
response, subscribe/push, probe and match, pull, and others.
Collaborative Tagging
Commonly referred to as folksonomy, a term coined by Thomas Vander Wal, Collaborative
Tagging refers to the ability of users to add “labels” (or tags) to link
resources with semantic symbols that themselves are grounded in a conceptual
domain (ontology). Major top-down efforts to create a semantic web have failed
to take hold, yet in the meantime, the rise of Collaborative Tagging has added a
new aspect to the creation of a common semantic layer for the Internet. The website
at http://del.icio.us, where users can apply labels to public bookmarks, is a prime
example of the Collaborative Tagging pattern.
Declarative Living and Tag Gardening
In the real world, people make statements about just about everything. Declarative
Living is the act of encoding those declarations in syntax that a machine can process,
and making them visible to other entities on the Web. Tag Gardening is the
act of harvesting the declarations to learn about the users’ collective state. This
pattern is grounded in the Collaborative Tagging pattern. An example is Twitter
(http://www.twitter.com), where users make declarations about their daily activities
that others can access. Even social networks such as Facebook, where people simply
“declare” existing social structures, are a specialized form of this pattern.
Semantic Web Grounding
The Semantic Web Grounding pattern assembles interactions that monitor the
links between declarations (e.g., “semantic tags”) and resources, as well as how
users interact based on those artifacts. It facilitates self-learning, self-healing software,
as observing the patterns of interactions can lead to inferences about the
relevancy of semantic declarations. Google Search is probably the best-known example
of this pattern, although many adaptive learning software systems embrace
it as well.
Persistent Rights Management
Persistent Rights Management is a pattern of users retaining their Create, Read,
Update, Delete (CRUD) rights on every copy of a digital artifact. As opposed to
simply securing the location of the original copy, this pattern bestows author rights
on all copies of a work. People sometimes confuse Digital Rights Management
(DRM) with this pattern, but although DRM is similar, there are differences. DRM
is a subset of Persistent Rights Management* addressing read access to digital
files,† whereas Persistent Rights Management encompasses finer-grained rights
that owners might need to control, including printing, viewing, modifying, and
more.‡ Adobe LiveCycle Rights Management Server and Microsoft’s Rights Management
Server are both adopters of this pattern.
Structured Information
The advent of XML and the ability to apply customized tagging to specific elements
has led to the rise of syntaxes commonly referred to as microformats. These are
small formats with highly specialized abilities to mark up precise information
within documents. The use of such formats, in conjunction with the rise of
XHTML, lets Internet users address content at a much more granular level than
ordinary HTML. The XML Friends Network (XFN) format is a good example of
this pattern.
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