Grid Services Orchestration with OMII-BPEL - Grid Computing: Infrastructure, Service, and Applications - page 198

through the minimal one-to-one mappings between BPEL activities and
their visual equivalences, the transition of abstract logic to concrete pro-
cess model can be facilitated without having to unveil the actual transla-
tion taking place under the cover. Furthermore, in response to frequent
changes of process dei nitions, for example, in scientii c experiments,
visual editing is much more efi cient. It must be noted that the target
users of BPEL are not only computer professionals who have the exper-
tise of developing BPEL processes in every detail, but also those domain
experts who have the real cases of workl ow logic but rather limited
technical background by way of contrast. This is particularly true
for Abstract Processes introduced in WS-BPEL 2.0 as nonexecutable
processes that only focus on logics in large instead of implementation
details. All in all, the design of primary importance of a productive mod-
eling tool is to ensure the modeling itself is well supported at all times.
We will see what useful functionalities BPEL Designer has provided us
in this section.
With the release of the home-grown Sedna editor, OMII-BPEL has made
available one of the i rst visual BPEL editors for the community. It was
a BPEL4WS1.1-compatible editing tool based on the Eclipse platform. In
addition to standard BPEL supports, Sedna has integrated advanced
features like parallel looping with l ow , macro process extensions,
deployment with ActiveBPEL, and so on. Being a fully functional BPEL
editor, Sedna was available to the public with early OMII distribution.
Some i rst-hand user feedback and requirements were therefore able to be
gathered and studied for successive developments.
Work on bringing BPEL to scientii c grid computing materialized with
the cooperation of the Eclipse-BPEL project in 2006. Largely led by IBM
and Oracle with volunteer contributions, the project was aiming to add
comprehensive support of BPEL to the Eclipse IDE, around which a set of
key functionalities can be offered to support the open-source development
of the advanced BPEL modeling environment. This includes a visual edi-
tor, a BPEL data model, a validation framework, a runtime framework,
and a debug framework.
Being very similar to Sedna, which has since been replaced, BPEL
Designer was developed as an Eclipse plugin, and builds on well-known
Eclipse plugin platforms like GEF, EMF, WTP, and so on. The consistent
look and feel of BPEL Designer should appear familiar to existing Eclipse
users. A screen dump is shown in Figure 8.1 .
The main editing area in the middle is where a process is composed
using constructs, mainly standard BPEL activities, which can be picked up
from the palette alongside. Constructs are connected and aligned auto-
matically. Container-constructs like scope , if , and so on can be collapsed or
expanded for a better spacing and viewing experience. Summary tips are
available when the mouse pointer hovers above. Declarations of variable s,
partner link s, correlation set s, and other process properties can be managed