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Berman, Fox, Hey (eds.). Grid computing.. Making the global infrastructure a reality (Wiley, 2003)(T)(1060s).djvu |
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Size 9.7Mb Date Nov 13, 2004 |
independent of the process (Web service) that produced the message...
This scenario is not meant to be innovative but rather to illustrate the purpose
of our architecture building blocks in a homely example...
Asynchronous collaboration has no special time constraint
and typically each community member can access the resource in their own fashion;
objects are often shared in a coarse grain fashion with a shared URL pointing to a large
amount of information...
The indirect mechanism is the most power-
powerful and is deployed in P2P systems such as JXTA by using XML-expressed advertisements
to link together those interested in a particular topic...
Supporting heterogeneous clients requires that
sophisticated shared display environments automatically change size and color resolution
to suit each community member...
In the next section, we discuss user
PEER-TO-PEER GRIDS 487
interfaces and suggest that the user-facing ports should not directly define the interface but
a menu allowing the client to choose the interface style...
Customized user-facing output port that delivers the selected view from step 1 from
the Web service to the client...
These components are often reliable, well
documented and maintained, and designed with the intention to be reused and customized...
• A storage service offering GridFTP transfer, an explicit TCP buffer-size tuning interface
as well as administration interfaces for management of files on local storage systems...
Typically, a
service is persistent (long-lived), but it may also be transient (short-lived, temporarily
instantiated for the request of a given user)...
As in a data integration system [9, 10, 11], the goal is to exploit
several independent information sources as if they were a single source...
Here, nodes, services, and
other content providers may publish (their) service descriptions and/or other metadata
to one or more nodes...
Content link and content provider
Content link: A content link may be any arbitrary URL However, most commonly, it
is an HTTP(S) URL, in which case it points to the content of a content provider, and
an HTTP(S) GET request to the link must return the current (up-to-date) content...
The structure of a content provider and its interaction with a registry and a client
are depicted in Figure 19.2(a)...
If it is an HTTP(S)
URL, then the current (up-to-date) content of a content provider can be retrieved (pulled)
at any time...
• Content: Given the link the current (up-to-date) content of a content provider can
be retrieved (pulled) at any time...
• Push registry: A publication tuple pushed from a content provider to the registry con-
contains not only a content link but also its current content...
Within a tuple set, a tuple is uniquely identified by its tuple
key, which is the pair (content link, context)...
if type="networkLoad" AND TC < currentTime () - 10), it calls the XQuery
document (URL contentLink) function with the corresponding content link in order
to pull and get handed fresh content, which it then processes in any desired way...
A content provider can publish a
dynamic pointer called a content
link, which in turn enables the
consumer (e.g...
The
introduction of service discovery as a new and additional auxiliary service capability
should require as little change as possible to the large base of valuable existing legacy
services, preferably no change at all...
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