Information Technology Reference
In-Depth Information
4.1 Introduction
In most cases, gateways and workflow management systems (and therefore their
workflows) are tightly bound to some small number of speci
c distributed com-
puting infrastructures (DCIs), and effort is required to enable additional DCI sup-
port. As a result, solving workflow management systems
DCI incompatibility, or
their workflow interoperability (Krefting 2011) issues are very challenging and
complex tasks. In this chapter we show a concept of how to enable generic DCI
compatibility, which is feasible for many major gateways and grid workflow
management systems (such as ASKALON (Duan 2005), MOTEUR (Glatard 2008),
WS-PGRADE/gUSE (Kacsuk 2012), etc.) on workflow level (and also on the job
level). To enable DCI compatibility among the different gateways and workflow
management systems, we have developed the DCI Bridge, which is also one of the
main components of the so-called
'
fine-grained interoperability approach (FGI)
developed by the SHIWA (SHaring Interoperable Workflows for large-scale sci-
enti
c simulations on Available DCIs) project (Plankensteiner 2013). In this
chapter we target the generic DCI Bridge service component and describe its
internal architecture, provide usage scenarios, and show how the DCI Bridge can
resolve the DCI interoperability issues between various middleware types (e.g.,
between gLite, ARC, and UNICORE).
4.2 The Generic Concept of DCI Bridge
In the WS-PGRADE/gUSE portal framework, the DCI Bridge provides flexible and
versatile access to all the important applied DCIs within Europe. In the previous
versions of gUSE, as many submitters had to be developed as there were different
DCIs to be supported. The DCI Bridge component originally was developed to
support only SHIWA
'
is FGI solution; however, later on it turned out that it is useful
for any OGSA Basic Execution Service 1.0 (BES) enabled workflow management
system to solve their DCI interoperability issues. The DCI Bridge is a web service
based application, which provides standard access to various distributed computing
infrastructures such as: service/desktop grids, clusters, clouds and web service-based
computational resources (it connects through its DCI plugins to the external DCI
resources). The main advantage of using the DCI Bridge as a web application
component of workflow management systems is that it enables the workflow man-
agement systems access to various DCIs using the same well-de
ned communication
interface (Fig.
4.1
). When a user submits a workflow, its job components can be
submitted transparently into the various DCI systems using the OGSA Basic Exe-
cution Service 1.0 (BES) interface. As a result, the access protocol and all the
technical details of the various DCI systems are completely hidden behind the BES
interface. The standardized job description language of BES is JSDL (Anjomshoaa
2006). Additionally, DCI Bridge grants access to a MetaBroker service called
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