Numerical Simulation through Web Services
by Stephan Springstubbe, Jürgen Klein and Ottmar Krämer-Fuhrmann
Simulation portals provide secure access to data and the use of different analysis and simulation tools via Internet. Benefits are a safe access independent of location or time, personalized services with an adequate user support, and modern security methods like certificate authentication or encryption. Thus simulation portals meet industrial requirements in a 'portable' environment.
The expansion of the Internet and the development of secure access and communication methods enable a new and integrative usage of simulation tools. Web portals offer the integration of data, applications, services and resources in a personalized environment.
The Internet or Intranet enable developers to access central resources such as databases or computer systems via a graphical user interface. This does not only reduce investment costs, but also keeps expenditures for installations and support as well as licenses at a minimum.
From Authentication to Simulation
Important components of a web portal are:
- user management - the basis for authentication
- object management - for the realization of 'user workspaces'
- control of processes incl. accounting of computer resources and license fees.
Modern authentication methods, safe communication and quick database connections allow clients to use resources via the portal independently of time or location.
Numerical Simulation in a Web Portal
Through increased computer power numerical simulation is becoming more important for the development of turbo machines. The software TRACE (Turbo-machinery Research Aerodynamic Computational Environment), developed by the Institute for Propulsion Technology of the German Aerospace Center (DLR) in Köln-Porz, provides a detailed insight into complex fluid processes.
|Figure 1: Time-accurate 3D-Simulation of a Propfan with TRACE (courtesy of DLR).
Fraunhofer SCAI integrated this software solution into a web portal, thus enabling a better use by the industry.
Individual Services for Users - the TRACE-Portal
Web portals cannot only be used easily by means of a browser, but also offer a personalized Internet environment and user guidance. This supports perfectly a variety of user roles like Internet surfers, registered users, licensed customers and administrators.
|Figure 2: Architecture of the TRACE-Portal.
In particular the role und group definition of users makes it easy to support various development teams in the best possible way. The portal solution is portable to other computer systems and can be customized to every application and service. Thus portals can easily be adapted to new technologies.
Client-Server Technology on the Basis of Sun ONE
The software Sun Open Network Environment (Sun ONE) is the basis for the implementation of the TRACE Portal. Sun ONE is Sun's standards-based software platform for building Web Services on Demand. Originally being developed for e-commerce applications, now Sun ONE has been adapted by Fraunhofer SCAI for scientific applications. Sun ONE supports web portal solutions with a modular architecture. The TRACE Portal consists of three components (see Figure 2): Web container, Enterprise Java Beans container and Compute server. Each of these components realize a web service interface and is therefore easily adaptable to new services or technologies. In the following we describe the portal architecture.
The simplest access to the portal server is via a browser. The browser realizes access to the public area by simple HTTP protocol, and for registered users to the restricted area by the HTTPS protocol using ssl encryption.
Alternatively web services or applications can access the simulation service directly. In both cases the client system communicates via Internet connection with the web portal server.
Web and Application Server
Server Module 'Web Container': The server module accessed by the client is the web container. It realizes the presentation layer forming the user interface. It is implemented by Servlets and Java server pages (JSP). The web container executes the user authentication and guides through all portal services by means of a graphical user interface. Different user roles are supported by the portal, so that each user works in a personalized web environment with individual services, account and workspace data.
Server Module 'EJB Container': The Enterprise Java Beans (EJB) container realizes the business logic and can be understood as an interface between the user and resources, like the database or the compute server. The EJB container is realized in Java.
Server Module 'Database': The database stores all data of the portal, like user data, virtual user workspace, version management and account data.
The most important web service for the user is the execution and control of numerical simulations. This is controlled by Enterprise Java Beans of the EJB container. The data access layer allows to upload data to the computing platform. TRACE simulations are executed on a multi-processor Sun-server or on a computational GRID.
The user can monitor and control computations. He is able to configure, start, stop or terminate simulation processes. Accounting is done automatically by the portal.
The portal is well suited for the use, if several departments are working with the same simulation code. Portal solutions support access to central resources, which minimize license fees, man power of installation, updating, and administration efforts.
Fraunhofer SCAI offers complete solutions for the conception, design and realisation of innovative Internet presentations. Portal solutions offering numerical simulation as a web service in a safe, user-friendly web environment, which can be used independent of location or time.
Ottmar Krämer-Fuhrmann, Fraunhofer SCAI