Support Platform (CGSP), and then compare CGSP with Service Domain (SD), which adopted as hosting environment for CFD GAP originally. At last we present.
Building CFD Grid Application Platform on CGSP Xinhua Lin1 , Yang Qi2 , Jing Zhao1 , Xinda Lu1 , Hong Liu2 , Qianni Deng1 , and Minglu Li1 1
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Department of Computer Science & Engineering, Shanghai JiaoTong University, Shanghai 20030, P.R. China {lin-xh,zhaojing}@sjtu.edu.cn, {lu-xd,deng-qn,li-ml}@cs.sjtu.edu.cn Department of Engineering Mechanics, Shanghai JiaoTong University, Shanghai 20030, P.R. China {luvanaki,hongliu}@sjtu.edu.cn
Summary. The Computational Fluid Dynamics (CFD) Grid Application Platform (GAP) is one of five major application platforms in ChinaGrid. It provides a Grid environment for different CFD applications which need high performance computing. In this paper, first we introduce the project background of ChinaGrid General Support Platform (CGSP), and then compare CGSP with Service Domain (SD), which adopted as hosting environment for CFD GAP originally. At last we present how to build the CFD GAP on CGSP and extend its functions for specified CFD application requirements. Keyword. CFD, GAP, CGSP, Service Domain
1 Introduction Computational Fluid Dynamics (CFD) integrates computational mathematics, computer science, hydromechanics, computer visualization, and etc. Its main research areas include computational hydrodynamics, computational aerodynamics, computational thermo-fluids, numerical weather forecast, and etc [Anderson95]. The CFD Grid Application Platform (GAP) in ChinaGrid is been built to provide a Grid environment for different CFD applications which need high performance computing. Another meaning of word “GAP” is we are trying to “bridge” the “GAP” between the CFD engineers and computer scientists. Currently we are building the CFD GAP on CGSP. 1.1 CGSP Project Background ChinaGrid General Support Platform (CGSP) is the fundamental of ChinaGrid. There are five application platforms running based on CGSP, such as image processing platform, CFD platform, bioinformatics platform, course
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on-line platform and large scale information processing platform. So CGSP is often called as “the platform of platforms”. CGSP is developed to meet the huge requirements from different research area, most of them need computational power, in China. CGSP is not only a software, like “Globus Toolkit”, the de facto standard of Grid. We can describe the relationship between CGSP and Globus as platform and toolkit. The CGSP include parts of modules from Globus, but more than that, such as job management, enhanced information service and packaging existing commandline style programs to Grid Service automatically. The members of CGSP development team are from the top 5 universities in China, and the demo version of CGSP will appear in October and the first version will be released at the end of this year.
2 Compare with Service Domain Service Domain (SD)[Tan03] is developed by IBM, shipped with Emerge Technology Toolkit (ETTK) which available in IBM alphaWorks, and now it is combined into WebSphere platform. Basically, SD is a web service registration center and it can invoke the web service registered. We have developed a prototype system of CFD GAP, which adopted SD as the hosting environment to integrate different CFD Web Services and invoke them from SD. 2.1 Service Domain Background SD is built from standard Web Services and Grid Services infrastructures, and it provides a higher level services for implementing Web Services and Grid solutions. SD uses three interfaces, which include service entry interface, service attachment interface and service policy interface, to describes a service sharing and aggregation model: The service entry interface is provided as a web service with an externally known Uniform Resource Identifiers service address. All the Web Service can be registered, executed and administered in SD; The service attachment interface is generated from the information registered for the provided services to support different dispatching; The service policy interface is used to set the intelligence rules for the operations of a SD. 2.2 Compare CGSP with Service Domain As we mentioned before, when we begin to building CFD GAP, we adopted SD as a hosting environment, and it seems work well. However, when we digging more deep into CFD Grid, we find something in SD is inconsistently with our requirements. At that time, we have a chance to participate the CGSP project, and the requirements of CFD applications are highly considered by
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the architects of CGSP. Based on the technical preview version of CGSP, CFD GAP works much better. Let’s take a deep look at what is different between CGSP and SD. Their goals are different. SD is developed for e-business, and it high considers the requirements from enterprise. For example in SD, users in same group can only have the same operations. It is a flaw in computational science area, where users want to have their own operations. Their functions are different. SD provides a service management, which in “service triangle”, SD plays the role of “service registry”. It is for service registration, not responsible for service providing or service deployment. While, CGSP is a platform, playing the roles both “service registry” and “service provider”. It packages the existing command-line style programs to web service or Grid service automatically. The Grid standard They’ve adopted are different. SD supports the Open Grid Service Infrastructure (OGSI) [Tuecke03], which will be no longer supported in the next generation Grid standard. Globus Toolkit 4 will adopt a new standard called Web Services Resource Framework (WSRF) [Foster04]. While begin to design the CGSP, architects agree to support the WSRF, and so most of CGSP functional modules are followed with WSRF standard. SD only support simple security infrastructure, users from different role groups simply enter the user name and password , then login into SD, invoke the web service registered in SD. This seem enough for enterprise usage. However, if put SD in wide area network, it will be cracked down soon by some evil programmers very easily. In CGSP, user need not only to enter the user name an password, but also the a certificate authority (CA) file get from the CA center. And every operation provided by CGSP needs to check the user ID. Users login to SD and they find some web services are listed in web pages. These services are binding by administrators. If the services are limited, users can find the service they want in the services list, however, if the service quantity is huge, users will feel tired to find right service. CGSP provides more effective way to find the service. It use the classification code to search the service in information service modules. In SD, after some sub hubs registered into main hub, main hub can dispatch jobs to these sub hubs, however, the way for dispatching is random. Though workload balancing is considered in SD, the supporting is very weak. CGSP provides the dynamic job scheduling and considers highly about the workload balancing. The final flaw about SD is it is a commercial product, and not open source, while CGSP is developed by universities in China, and it is open source and free of charge.
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3 CFD specified in GAP In some sense, CGSP is a platform and CFD GAP is an application based on CGSP. CGSP provides the infrastructure for CFD GAP, and CFD adds some specified functions modules. We propose a concept triangle, which means easy to use for end users, easy to develop applications for application developers and experts, easy to manage for platform administrators. 3.1 Easy-to-use Most of CFD applications are command-line style, and it is difficult to use for CFD beginners. The GAP adds the visualization layer to CFD applications, in another words, a friendly User interface (UI). by UI, end users have no need to remember what the parameters of applications mean and how to use them. The other contribution of GAP is CFD work flow template, which can be used in more than 80% CFD applications. It includes three steps: preprocessing, calculation and postprocessing. Preprocessing is the first step in building and analyzing a flow model. It includes building the model (or importing from a CAD package), creating a mesh. Some commercial preprocessing tools can be found, such as GAMBIT, G/Turbo and TGrid. However, in most cases, CFD researchers develop their own specific preprocessing programs. After preprocessing, the Domain Decomposition divides the input mesh to some small meshes and the CFD solver does the calculations and produces the results. The most widely used commercial products are FLUENT and FloWizard. FLUENT is used in most industries. FloWizard is the first generalpurpose CFD product for designers built by Fluent. Also, large numbers of specific programs are written by researchers. Postprocessing is the final step in CFD analysis, and involves organization and interpretation of the data and images. most of commercial software includes full postprocessing capabilities. And some free and open source data visualizing tools are also widely used. 3.2 Easy-to-develop The CFD GAP is not only for end users, but also for some CFD experts. what are the requirements from these experts? In fact they want to use GAP without extra learning cost, which means they want to use the Grid without knowing what is Grid and what is Globus. So GAP provides a very convenient way to package existing CFD applications into web service. After these experts login GAP, they upload the the CFD programs to GAP, binary code is enough, and then select the target machine, which will run the CFD program and publish the web service. That is all about the deploy a CFD web service in GAP. CFD experts do not have to know WSDL, XML, web service and etc.
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Fig. 1. General CFD Work Flow Template In Three Steps
Currently, GAP can support packaging sequence program running both on Windows and Linux. Parallel programs only running on Linux using MPICH can be packaged automatically, however, the other feathers will be implemented in the future. CFD applications always have large data files, most of them are hundreds megabytes and some are even more than gigabytes. GAP provides two ways to deal with these large files. First way is moving the data file by ftp. Users can use a ftp applet in web browser move the big file. However, if the file is too big, GAP provide another way, which by using the data management in CGSP returning the URL of a data file. Users can input the Unique Reference Link (URL) as a parameter to CFD service, then the service will find the data file by URL automatically. 3.3 Easy-to-manage All modules both from CGSP and GAP have the GUI for manage the the way very easily. Platform administrators can use these GUI to manage the CGSP and GAP very conveniently.
4 Conclusion In this paper, we have introduced the CFD GAP in ChinaGrid from following two perspectives: (1) CGSP is well-developed general Grid platform comparing with SD in some different aspects.
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(2) CFD GAP is built on CGSP and it adds some CFD application specified functions.
References [Anderson95] J. D. Anderson. Computational Fluid Dynamics: The Basics with Applications. McGraw Hill, US, (1995) [Tan03] Y.-S. Tan, B. Topol, V. Vellanki, and J. Xing. Business service grid, part 1: Introduction, manage web services and grid services with service domain technology. Technical report, Grid computing in IBM develperworks (2003) [Tuecke03] S. Tuecke, K. Czajkowski, J. Frey, S. Graham, C. Kesselman, T. Maquire, T. Sandholm, D. Snelling, Vanderbilt. Open Grid Services Infrastructure (OGSI) Version 1.0. Global Grid Forum (2003) [Foster04] I. Foster, J. Frey, S. Graham, S. Tuecke, et al, Modeling Stateful Resources with Web Services,Technical report, Globus alliance (2004)
