4,075 research outputs found
VOSpace: a Prototype for Grid 2.0
As Grid 1.0 was characterized by distributed computation, so Grid 2.0 will be characterized by distributed data and the infrastructure needed to support and exploit it: the emerging success of Amazon S3 is already testimony to this. VOSpace is the IVOA interface standard for accessing distributed data. Although the base definition (VOSpace 1.0) only relates to flat, unconnected data stores, subsequent versions will add additional layers of functionality. In this paper, we consider how incorporating popular web concepts such as folksonomies (tagging), social networking, and data-spaces could lead to a much richer data environment than provided by a traditional collection of networked data stores
Chapter 59: Web Services
Web services are a cornerstone of the distributed computing infrastructure that the VO is built upon yet to the newcomer, they can appear to be a black art. This perception is not helped by the miasma of technobabble that pervades the subject and the seemingly impenetrable high priesthood of actual users. In truth, however, there is nothing conceptually difficult about web services (unsurprisingly any complexities will lie in the implementation details) nor indeed anything particularly new.
A web service is a piece of software available over a network with a formal description of how it is called and what it returns that a computer can understand. Note that entities such as web servers, ftp servers and database servers do not generally qualify as they lack the standardized description of their inputs and outputs. There are prior technologies, such as RMI, CORBA, and DCOM, that have employed a similar approach but the success of web services lies predominantly in its use of standardized XML to provide a language-neutral way for representing data. In fact, the standardization goes further as web services are traditionally (or as traditionally as five years will allow) tied to a specific set of technologies (WSDL and SOAP conveyed using HTTP with an XML serialization). Alternative implementations are becoming increasingly common and we will cover some of these here. One important thing to remember in all of this, though, is that web services are meant for use by computers and not humans (unlike web pages) and this is why so much of it seems incomprehensible gobbledegook.
In this chapter, we will start with an overview of the web services current in the VO and present a short guide on how to use and deploy a web service. We will then review the different approaches to web services, particularly REST and SOAP, and alternatives to XML as a data format. We will consider how web services can be formally described and discuss how advanced features such as security, state and asynchrony can be provided. Note that much of this material is not yet used in the VO but features heavily in IVOA discussions on advanced services and capabilities
Chapter 8: Web-based Tools—CARNIVORE
Registries are an integral part of the VO infrastructure, yet the greatest exposure that
most users will ever need to have to one is discovering resources through a registry
portal. Some users, however, will have resources of their own that they need to register
and will go to an existing registry to do so, but a small number will want to set up
their own registry. They may have too many resources to register with an existing
registry; they may want more control over their resource metadata than an existing
registry will afford; or they may want to set up a specialized registry, e.g. a subjectspecific
one. CARNIVORE is designed to offer those who want their own registry
the functionality they require in an off-the-shelf implementation. This chapter describes
how to set up your own registry using CARNIVORE
Critical realism in conversation with postmodern theology, science and hermeneutics
https://place.asburyseminary.edu/ecommonsatsdissertations/1993/thumbnail.jp
Searching for the scale of homogeneity
We introduce a statistical quantity, known as the function, related to
the integral of the two--point correlation function. It gives us
straightforward information about the scale where clustering dominates and the
scale at which homogeneity is reached. We evaluate the correlation dimension,
, as the local slope of the log--log plot of the function. We apply
this statistic to several stochastic point fields, to three numerical
simulations describing the distribution of clusters and finally to real galaxy
redshift surveys. Four different galaxy catalogues have been analysed using
this technique: the Center for Astrophysics I, the Perseus--Pisces redshift
surveys (these two lying in our local neighbourhood), the Stromlo--APM and the
1.2 Jy {\it IRAS} redshift surveys (these two encompassing a larger volume). In
all cases, this cumulant quantity shows the fingerprint of the transition to
homogeneity. The reliability of the estimates is clearly demonstrated by the
results from controllable point sets, such as the segment Cox processes. In the
cluster distribution models, as well as in the real galaxy catalogues, we never
see long plateaus when plotting as a function of the scale, leaving no
hope for unbounded fractal distributions.Comment: 9 pages, 11 figures, MNRAS, in press; minor revision and added
reference
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