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by user programs. A user program requests execution of SSF workflows by means
of including relevant function calls with necessary parameters, i.e., input and output
file names. Advanced-use workflow implements
work
fl
ow caller functions,
which
handle the Remote API calls required to execute the requested SSF workflows. The
workflow caller functions simply use language speci
c functionality for executing
external scripts that will use Remote API to run the corresponding SSF workflows.
The script for a speci
c SSF workflow mainly accomplishes the following tasks:
Con
gures the workflow using the input
files passed as arguments in the
function call,
Submits the prepared workflow by using Remote API,
Waits for the workflow execution to complete, and
Downloads the workflow output to the
file speci
ed as an argument in the
function call.
12.3.3 SSS-Gateway Portlets
SSS-Gateway includes seven simple service level portlets, each of which corre-
sponds to a particular SSF, and an advanced service level portlet. These portlets
provide gateway users with an easy-to-use GUI through which they can con
gure
and run the workflows developed in SSS-Gateway.
Although the structure of each portlet varies depending on the corresponding
workflow, all the portlets provided by SSS-Gateway consist of components for
handling the following user actions:
Uploading the necessary input
files,
Con
guring the workflow options,
Executing the workflow, and
Examining and/or downloading the workflow outputs.
The portlets provide different input interfaces depending on the corresponding
workflows. The interfaces of SSF2 and advanced service level portlets can be seen
in Fig.
12.2
as examples. The SSF2 portlet provides
file upload interfaces for two
input
files, a model selection interface which allows multiple selections, and an
option to choose one of the supported estimation methods. The advanced service
level portlet, on the other hand, provides a single
file upload interface for uploading
user program bundles, a display frame for listing the
files in the bundles, and a
dialog window for displaying the uploaded source code. The other portlets also
include similar elements for uploading input
files, selecting models, specifying
methods to be used, and setting values of modi
able parameters and options. SSF4
and SSF6 portlets additionally provide another input method for specifying the site
region of interest. They provide a map interface through which the user is able to
specify a rectangular site region interactively instead of manually entering the
boundary coordinates of the site region.
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