The Institute of High Energy of Physics, Chinese Academy of Sciences

1. The Institute of High Energy of Physics, Chinese Academy of Sciences LFC Server LFC Server Sharing LCG files across different platforms Cheng Yaodong, Wang Lu, Liu Aigui, Chen Gang Yaodong.cheng@ihep.ac.cn Currently more and more heterogeneous resources are integrated into LCG. Sharing LCG files across different platforms, including different OS and grid middleware, is a basic issue. We implemented web service interface for LFC and pseudo LCG file access commands based on the LFC WS and globus Java CoG Kit. By using the tool, user can access LCG files on a variety of platforms transparently and achieve high-performance data transfer as well. The following sections describe the architecture, security, implementationand an example of use scenario. In figure 1, left side is the GFISH server based on SLC OS and GFAL, LCG_util and so on, whereas the right side is the client and pseudo LCG DM commands which are possible shell scripts on Linux, or bat files on Window. The client is only a fat jar package, and it can be downloaded easily to where LCG DM commands are needed. GFISH is a tool which allows user to access grid files and other files transparently, such as, “/castor”, “/dpm”. It includes some commands and APIs. GFISH WS server is developed by using gSoap Web services tool. In fact, GFISH WS is web service for LFC and some other file systems. Client is designed and implemented on basis of JVM (JAVA virtual machine), axis tool and CoG jglobus. SRM, GRIDFTP RFIO… LCGSE Pseudo LCG DM GFISH WS (gsoap) MyProxy Server GFISH Client (axis) GFAL, lcg_util JVM Linux (SLC) Linux, windows… Figure 1: The architecture of GFISH WS GFISH WS provides two methods to guarantee the security, one is session-based, and another is GSI-based. The two methods are shown in figure 2. In session-based mode, user logs in GFISH WS server and get session ID firstly. During the session, client sends requests with session ID, then WS server access third-party resource on client’s behalf by using user’s credential retrieved from MyProxy server. In GSI-based method, Client and server do mutual authentication by verifying grid certificate, then server creates a proxy for client and use it to connect third-party server in behalf of the client. ① ② ③ ④ A: session-based ① ② ③ B: GSI-based GFISH Client GFISH Client GFISH Server GFISH Server Figure 2: Security in GFISH WS Grid interoperability is an attractive work now, which aims to submit jobs from one grid infrastructure to another transparently. Typically, gateway nodes are introduced, that is also named gateway-based interoperability as shown in figure 3. Gateway is just a logical component, it can be handled as “facade” of underlying grid infrastructure. Here we take it as an example of GFISH WS use scenario. Suppose the interoperability of LCG and other Unknown Grid (UG) which is not compatible with GSI and GridFTP. Before using GFISH WS, consider the case that one gLite job is scheduled to UG platform, moreover, “lcg-cp” is used in the job to get large input data. At this time, it isn’t possible to run because “lcg-cp” doesn’t exist on UG platform. However, after the job find “lcg-cp” doesn’t exist, it can get GFISH client jar package from GFISH WEB as shown in figure 3. Then, the job can retrieve credential from MyProxy server, connect LFC server through GFISH WS server, and copy data from LCG SE by using pseudo “lcg-cp” command in GFISH client (described in dashed line). Actually, GFISH client is a small LCG DM environment, which can be built easily on demand. LCG RB GFISH WSServer GFISH WEB LCG SE gataway LCG UI Extended LCG CE UG Resources GFISH Client UG Client MyProxy Server Figure 3: An example of use scenario Computing in High Energy and Nuclear Physics, Victoria, British Columbia, Canada from 2-7 September 2007