Support for Cooperative Experiments in e-Science: From Scientific Work flows to Knowledge Sharing - Identification of Ligand Binding Site and Protein-Protein Interaction Area - page 150

(1) SOAP call (LWS1, Method,
dataURL1)

(6) SOAP call (LWS1, Method,
dataURL2)

Workflow
Engine

(5) SOAP Response
(dataURL2)

(7) SOAP Response
(dataURL3, data Object)

Tomcat Container Tomcat Container

(3) Call Service/Process
Files Stream ProxyWS LWS1

ProxyWS

LWS1

LWS2

LWS2

(4) Save data to remote
location/feed
VRS Server

LWS3

LWS3

VRS
Server

VRS
Server

CRS CRS

(2)GetFile/getData(URL1)

LFC

GridFTP

SSH

Fig. 7.7 The ProxyWS architecture. With the use of the VRS and the VRSServer, web services
may access data from remote locations, or other web services which helps ameliorate the data
isolation problems of Web services used in scienti fi c work fl ows

To address these problems we introduced ProxyWS: a web service that is able to
access data from remote resources (GridFTP, LFC, etc.) using the Virtual Resource
System (VRS), a Java API used by the VBrowser 10 to provide a single access
point to grid-enabled systems. Additionally, ProxyWS is able to transport larger
volumes of data produced by both legacy and new web service implementations.
For ProxyWS to be able to provide better data transfers to legacy web services, it
has to be deployed in the same Axis-based container, just like a normal web service.
This enables clients to make proxy calls to ProxyWS instead of a legacy web service
(Fig. 7.7 ). Consequently, ProxyWS returns a SOAP message containing a URI
referring to the data location, which might be any remote or local data resource, as
long as it is supported by the VRS instead of the actual data. For new implementa-
tions, ProxyWS is used as an API that can create data streams from remote data
resources and other web services using ProxyWS. This allows web services produc-
ing large amounts of data to be connected in a data pipeline, something that could
optimize workflow execution (Koulouzis et al. 2008 ). Thus, with the introduction of
ProxyWS we have a centralized control flow with all the benefits of distributed data
flow for new and legacy web services.

10 http://www.vl-e.nl/vbrowser