The use of grid computing is gaining momentum through its use by a number of leading application vendors including CSG Systems, IBM, and Oracle, among others. In this article we will review grid technology, available grid toolkits, and finally what development environments exist to build grid-enabled applications. This article will represent the first in a series of two on the grid. The next article will explain how the grid works and how companies are exploiting the use of this technology. 

Grid Technology Review

Grid Computing has evolved from distributed or clustered computing and virtualizes heterogeneous shared resources to form a large virtual computer. The biggest difference between true grid computing and distributed or clustered computing is the exploitation of heterogeneous shared resources – neither distributed nor clustered systems can work with disparate hardware or operating systems. Grid computing improves system performance, availability, scalability, reliability, and security through standardizing the integration of these heterogeneous shared resources. This integration is made possible by a number of standards driven by the Global Grid Forum/Foundation (GGF) including Open Grid Services Architecture (OGSA), Open Grid Services Infrastructure (OGSI), and finally Web Services Description Language (WSDL). The GGF consists of scientists, educators, and other professionals from around the globe who are committed to bringing this technology into prime time. While all this may seem like alphabet soup to you right now, some amazing progress has been made to the point where we are now seeing production applications rolling out that are OGSA/I compliant which means the standards are not only maturing but they actually work in production. IBM’s On Demand strategy largely emphasizes the use of grid technology as do a number of other leading companies who have realized the benefits of building their applications to exploit the grid. 

One of the most significant contributions to grid computing has been the evolution of the Grid Toolkit that is currently in its third rendition (this toolkit is also referred to as GT3). GT3 [1] has allowed companies curious about building grid applications to download a complete royalty free platform on which they can build OGSA/I complaint applications. Unlike previous versions of the grid toolkit, GT3 was based on standard Web Services technologies such as Simple Object Access Protocol (SOAP) and Web Services Description Language (WSDL) that has catapulted its use in web service applications. The next generation of the grid toolkit (GT4) is due out near the end of 2004 or the beginning of 2005 that should further drive adoption of grid services. 

OGSA (Open Grid Services Architecture) standardizes all the services in grid applications (job management services, resource management services, security services, etc.) by specifying a set of standard interfaces for these services. OGSI (Open Grid Services Infrastructure) gives a formal and technical specification for Grid Services. Globus Toolkit (current version 3) is a complete implementation (software toolkit) of OGSI. Consider the following simple analogy. OGSA (the definition) is the blueprint for architects to show what a building (grid) looks like. OGSI (the specification) is the structure design for engineers to support architects' vision for the building (grid). GT3 is the bricks, cement, and beams for the building (grid).  

The three most widely used grid toolkits are GGF’s GT3, IBM’s Grid Toolbox V3 for Multiplatforms, and Sun Microsystem’s Grid Engine 5.3. These toolkits are compared in Table 1.0. Lets describe what is included in each one. 

Global Grid Forum/Foundation (GGF) Grid Toolkit 3 (GT3)

The major GT3 components are resource management, information services, data management, and security:

• Grid Resource Allocation Management (GRAM): resource allocation, job submission and management.

• Monitoring and Discovery Service (MDS): collects information in the Grid for querying, based on Lightweight Directory Access Protocol (LDAP).

• Grid File Transfer Protocol (GridFTP): supports data transfer among Grid nodes.

• Grid Security Infrastructure (GSI): certificate-based grid security infrastructure.

GT3 is a very complicated toolkit – at least currently. While feature rich, it can be very time consuming to configure, install, and operate. Actual install time on Sun/Solaris is around 7 hours. It is also unstable on some platforms that only provide basic support (Sun/Solaris). If you are going to use GT3, your best bet is to use it on SuSE or RedHat Linux.

IBM Grid Toolbox V3 for Multiplatforms V1.1

IBM Grid Toolbox V3 for Multiplatforms V1.1 [2] implements the OGSI standards and provides the tools to build, develop, deploy, and manage grid services. It is a collection of components including the Globus Toolkit Version 3 and others:

• A single installation process: IBM Grid Toolbox ships both wizard-based and silent installation methods. Users are relieved from the pain to install prerequisite packages for open source GT3. The IBM Grid Toolbox installation on Pentium-based PC or xSeries takes around 40 minutes.
• A grid services runtime based on the OGSI specification: An embedded version of the IBM WebSphere Application Server - Express V5.0.2 is provided as the grid services container. It replaces the “standalone” container provided by GT3 for commercial-grade support. The Web and EJB containers support J2EE enterprise applications, which open source GT3 cannot handle. 
• Development tools: Enhancements and tools are provided which assist with building, packaging and deploying grid services and applications. This feature greatly reduces the complexity of Grid Services development and deployment. Open source GT3 cannot do that.
• A management interface: A web browser-based interface called the IBM Grid Services Manager provides easy grid-wide management for administrators.
• Configuration and administration commands: Command-line based scripts for common actions are provided for administrators.
• Additional enhanced grid services: IBM provides additional functionality including discovery via service group, policy management, and Common Management Models (CMM) Services.

The limitations of IBM Grid Toolbox is its supported environments (no Solaris!):

• IBM xSeries servers running Red Hat Enterprise Linux AS 2.1 or SuSE Linux Enterprise Server 8.
• IBM pSeries servers running SuSE Linux Enterprise Server 8.
• IBM pSeries servers running AIX 5L for POWER V5.2.0.10.
• IBM iSeries servers running SuSE Linux Enterprise Server 8.
• IBM zSeries servers running SuSE Linux Enterprise Server 8 SP2 (31-bit version only).

IBM Grid Toolbox on all these platforms is stable and follows the OGSI standards. IBM Grid Toolbox works fine with Linux RH Advanced Server 2.1, RH 8.0/9.0, and SuSE on Pentium processors, not only IBM xSeries servers. So, our future clients don't have to use IBM servers. Like GT3, IBM Grid Toolbox is free. 

SUN Grid Engine 5.3

SUN’s Grid Solution does not implement OGSI standards [4]. Sun Grid Engine 5.3 system contains four types of hosts: Master, Execution, Administration, and Submit. The Master runs master and scheduler daemons, which control all Sun Grid Engine components, such as queues and jobs. Execution hosts have permission to execute Sun Grid Engine jobs. Administration hosts carry out administrative activity for the Grid system. Submit hosts allow for submitting and controlling batch jobs only. For example, user who logs into a Submit host can submit jobs via "qsub", control job status via "qstat". Besides the command-line interface, Sun Grid Engine system also provides graphical user interface, called "QMON". 

Sun Grid Engine has such advantages:

• Sun Grid Engine allows users to submit jobs to queues. Master and scheduler daemons determine which Execution host to run the tasks. In case some Execution hosts crash, Sun Grid Engine can use other Execution hosts to failover transparently. The open source GT3 and IBM Grid Toolbox require clients (user commands or programs) to specify remote hosts to run tasks. In order to achieve reliability and scalability for a Grid, a Sun Grid Engine could be used as a Grid scheduler.

• Sun Grid Engine is a system for cluster management, rather than real "Grid Toolbox". It does not implement OGSI standards, nor support Grid Services. Unlike IBM Grid Toolbox, Sun Grid Engine could not allow Grid/Web Services deployment, but only support script-based job management.

• The Master host design in Sun Grid Engine might be the weakness of Sun Grid system. In case of Master node crashes, the whole system will break down.

Sun Grid Engine System could perform clustering management. Sun Grid Engine can integrate with Globus Toolkit to achieve user transparency of task submission and failover [5]. Other open source projects, like Condor [6] and OpenPBS, can be other options for clustering management too. Table 1 shows a side-by-side comparison of the different Grid toolkits. 

Table 1: Grid Container Comparison

Grid/Web Service Development Tools

Borland's JBuilder [8] and IBM's WSAD [7] (WebSphere Studio Application Development) are the top-two among integrated development environments (IDEs) for J2EE and Web Services development. Both are powerful development tools for Java, J2EE, EJB, JSP, Servlet, XML, UML, and Web Services. Here are some important factors to consider when buying an IDE for grid services development:

• Application server compatibility. WSAD can be integrated with WebSphere, WebLogic, and Tomcat application servers; JBuilder supports WebLogic, JBoss, WebSphere, Sun One, Borland, Oracle9i, Sybase, and Tomcat servers.

• Web Services. WSAD has more wizards for Web Service generation, with built-in WebSphere application server that speeds up debugging and testing Web Services. For example, generate Web Services from EJB, JavaBean, DADX (Document Access Definition Extension). JBuilder has limited function for Web Services.

• GT3-based development. IBM contributes to Globus Toolkit development, so WSAD supports GT3-based projects. In other words, developers can start/stop GT3 container, work on Grid Services inside the GT3 WSAD projects. JBuilder cannot do that.

• OS platform support. WSAD supports Linux and Windows. JBuilder supports Linux, Windows and Solaris.

• Price. IBM WSAD $4335, Borland JBuilder $3500.

IBM WSAD might be a better choice, if the IBM Grid Toolbox is used. It has some lock-in features with IBM WebSphere application server, IBM DB2 database, though. JBuilder seems more open to different platforms (especially Solaris) and application servers. Technical supports are crucial factors too. Table 2 displays a side-by-side comparison of the two IDEs. 

IBM Grid Toolbox (free now) comes with IBM WebSphere Application Server – Express (web server). There might be a way to configure this web server/container (in following figure) to balance workload across Grid servers and failover Grid server crash. 

Table 2: Top-two Java IDE Comparison 

IBM WSAD or Borland JBuilder? Both are powerful. It depends on the technical support you could get from IBM or Borland as well as your future customers’ requirement for application server, web server, and so on. The fact that you can now purchase enterprise quality development environments that allow you to build grid enabled web services is a good sign that we are beyond the scientific theory stage in the evolution of grid services.  

References:

[1] Globus Toolkit Home Page http://www.globus.org
[2] IBM Grid Toolbox V3 for Multiplatforms V1.1 Introduction. http://www-1.ibm.com/grid/pdf/grid_toolbox.pdf
[3] IBM Redbook: Grid Computing with the IBM Grid Toolbox. 04/2004.
[4] Sun Grid Engine 5.3 Administration and User’s Guide. 10/2002.
[5] EPIC - Sun Grid Engine Integration with Globus Toolkit 3 http://www.lesc.ic.ac.uk/projects/epic-gt3-sge.html
[6] Condor Installation. http://grid.phys.uvic.ca/docs/uberdoc/node16.html
[7] IBM WebSphere Studio Application Server. http://www-306.ibm.com/software/awdtools/studioappdev/
[8] Borland JBuilder X. http://info.borland.com/techpubs/jbuilder/

Special thanks to Henry Zeng for his help with this article.
 

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