Biomedical Engineering Reference
In-Depth Information
The caCORE technology provided for basic levels of interoperability but was
somewhat technology dependent (e.g., all APIs* were implemented in Java)
and it lacked both a means to identify which systems had data that were rel-
evant to a particular biomedical question and a robust, federated security
infrastructure.
The solution to these problems was provided by an extension of globus [14]
based grid technology. Grid technology provided three major benefi ts to
caBIG. First, it allowed for the creation of a technology-neutral adapter layer
that could be used to provide access to APIs regardless of the technical imple-
mentation of the underlying system. Second, it provided for discovery and
advertising of services. Finally, grid technology contained the seeds of a power-
ful, federated security environment that could be extended to meet the needs
of caBIG. The specifi c implementation of grid technology used by caBIG is
called caGrid [15], and it is shown schematically in Figure 17.2. Conceptually,
caGrid can be subdivided into fi ve functional areas: data and analytical ser-
vices, metadata services, higher order or workfl ow services, security services,
and client applications. Data and analytical services contain the information
and tools that are provided by and made available to the cancer research com-
munity. Higher order/workfl ow services such as the federated query processor
(that mediates queries into multiple systems) and workfl ow engines [caBIG
utilizes both Business Process Execution Language (BPEL) and the Taverna
[16] workfl ow engine] enable service marshaling to perform complex tasks
beyond the scope of any single system. Metadata services provide access to
information that describes the systems or the data contained in those systems.
Data and Analytical Services
Metadata Services
caArray Service caGWAS Service Other Services
caDSR Service Vocabulary Service
GME Service
Index Service
Client Applications
Security Services
Authentication Service
Dorian
GTS
Grid Grouper
Higher Order Services
Federated Query Processor
Workflow Engine
Delegation Service
Figure 17.2
Schematic representation of services in caGrid.
*An API is software that enables other programmers to access data or capabilities that exist
within a computer system. The presence of public (i.e., described and accessible) APIs greatly
facilitates integration of software systems and prevents “vendor lock.”
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