WS-PGRADE/gUSE and Clouds - Science Gateways for Distributed Computing Infrastructures - page 98

authentication portlet to set their CBP credentials (username and password), and the
workflow portlet can be used to con gure workflows based on available resource

and application information fetched from the CBP. Once a workflow is properly
con

gured, it can be submitted. From this point on, the workflow interpreter (WFI)
component of gUSE is responsible for creating job instances to be managed by the
DCI Bridge. If a node/job of the submitted workflow is con gured for execution in a

cloud, the DCI Bridge is CBP plugin is responsible for managing the execution of the

job with the help of the CBP service (creates corresponding CloudBroker jobs and
uploads input

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files from the portal server to the cloud storage attached to the selected
cloud resource). From this point on, it is the CBP service ' s task to create the

requested virtual machine based on the selected application s deployment for run-

ning the job, and to perform any necessary data transfer between the virtual machine
and the cloud storage used.
All communication between WS-PGRADE/gUSE and the CBP service requires
authentication, which is based on usernames and passwords. Thus, in order to use the
CBP services, one should posses such credentials. In the case of the WS-PGRADE

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workflow developer mode (where all the functionalities like workflow creation and
con

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guration are exposed for the user), these credentials have to be entered, meaning
that the portal user must have registered in the targeted CBP service, and during this
registration step has received the necessary username and password. However, the
need to enter these credentials can be eliminated by the “ robot certicate ” feature of
WS-PGRADE/gUSE, where the workflow developer can attach different credentials
to the nodes of the workflow he/she has developed, and users of this workflow will
make use of the attached credentials in a transparent way (see Chap. 6 for details of
robot certi cates).

7.4.1 User Interface for Configuring Nodes for Clouds

The web interface WS-PGRADE/gUSE has been extended at different points: a
new authentication portlet has been created to offer a way to enter credentials for
each CBP service con gured in the DCI Bridge, the concrete workflow con gu-

ration has been extended with possibilities to con gure properties of CBP jobs with

cost estimate display, and cost is displayed for executed workflows as well.

7.4.1.1 CloudBroker Authentication Portlet

One gateway can be connected to several CBP services. For example, in the SCI-
BUS project CloudBroker provides two platforms for project members. The

rst
one is the development platform where the research experiments of the gateway and
platform developers can be carried out. The second one is the production platform
that is a stable cloud access service provided for the gateway end-users and
application developers.