About AHE
The Application Hosting Environment, AHE [1], developed at University College London, provides
simple desktop and command line interfaces, to run applications on resources provided by national
and international grids, in addition to local departmental and institutional clusters, while hiding from
the user the details of the underlying middleware in use by the grid. In addition, a mobile interface
for Windows Mobile based PDAs is available, and an iPhone interface is in development. The
AHE is able to run applications on both UNICORE and Globus grids, meaning that a user can
use a single AHE installation to access resources from the UK NGS and DEISA for example.
Development of an EGEE connector for AHE is currently underway.
The AHE is designed to allow scientists to quickly and easily run unmodified, legacy applications
on grid resources, manage the transfer of files to and from the grid resource and monitor the status
of the application. The philosophy of the AHE is based on the fact that very often a group of
researchers will all want to access the same application, but not all of them will possess the skill or
inclination to install the application on remote grid resources. In the AHE, an expert user installs
the application and configures the AHE server, so that all participating users can share the same
application. This community model draws a parallel with the modus operandi of numerous scientific
application communities.
The AHE client is easily installed on an end users machine, requiring only that they have a Java
installation and an X.509 certificate for the grid, which they want to access. The client package
contains both GUI and command line clients which interoperate, allowing jobs launched with the
GUI client to be manipulated with the command line tools and vice versa, and also application
workflows to be easily constructed.
Within the MAPPER AHE is connected to the GridSpace workflow management system, in order to
allow AHE hosted applications to be orchestrated as workflow components using GridSpace. AHE
is used to hide the complexity of running applications on the grid, such as where an application
binary is located, what environment variables need to be set to run the application, and even the
back end interface used to communicate with grid resource. This simplifies the process of creating
and running a workflow. The workflow designer doesn't need to know where the application resides
or how to start it, they simply issue a command to AHE to run the tool. GridSpace contains an
extension that makes use of the AHE's client API in order to launch and monitor applications.
[1] P. V. Coveney, R. S. Saksena, S. J. Zasada, M. McKeown and S. Pickles, "The Application
Hosting Environment: Lightweight Middleware for Grid-Based Computational
Science", Comp. Phys. Comm., 176, 406-418 (2007).