Gateway Portal 

by Marlon Pierce and Stephen Wilkerson 

ARL-TR-3154 March 2004 

Approved for public release; distribution is unlimited.
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Army Research Laboratory 

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ARL-TR-3154 March 2004 

Gateway Portal 

Marlon Pierce and Stephen Wilkerson 

Computational and Information Sciences Directorate, ARL 

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14. ABSTRACT 

One problem facing researchers needing high-speed computations for their research is easy access to High Performance Computing (HPC) resources. 

At one time, a majority of the users in the research community had two machines: one Unix workstation for research and another personal computer 

(PC) type machine for word processing, e-mail, and creating publications and presentations. As the speed and popularity of PCs have grown, their roll 

has also changed to include pre- and post-processing of complex jobs as well as their other functions. Moreover, these machines have started 

replacing the more expensive Unix-based workstations for graphics and other multimedia functions. While PC machines can be made to emulate a 

Unix X-Windows environment, this requires users to understand both operating systems and have X-software loaded on the PC client. In some cases, 

unfortunately, users are becoming more PC literate and less Unix knowledgeable. Not knowing the correct commands has led to difficulties in 

transferring files, writing job scripts, and the like, for HPC access. 

One solution is to make the access to HPC assets available through a web interface. A web server can establish a connection between the user’s PC 

and HPC assets, allowing file transfers and job submission. This interface eliminates the need for the user to understand how to write GRD scripts and 

the problems associated with setting up HPC computer runs, while allowing the scientist to concentrate on the application of the computation for his or 

her research. However, there are security concerns associated with Web access to HPC. This report addresses the implementation of a Web solution 

using Java, Java Beans, and Java Server Pages (JSP) on an Apache web server running Tomcat. Examples from the Gateway interface are used as 

evidence of this technology as a solution to a growing problem. 

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HPC, Gateway, Tomcat, Java, JSP 

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Stephen A. Wilkerson 

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iii

Contents 

List of Figures iv

List of Tables iv

1. Introduction 1

2. Approach 2

3. Functionality 4

4. The Gateway Portal 5

5. Security Model 7

6. Gateway GUI Interface 10

7. Conclusions 13

8. References 15

Distribution List 16 
iv

List of Figures 

Figure 1. Gateway server approach schematic. ..............................................................................2 

Figure 2. Gateway architecture.......................................................................................................6 

Figure 3. Login screen. .................................................................................................................11 

Figure 4. Main screen. ..................................................................................................................11 

Figure 5. Submitting jobs..............................................................................................................12 

Figure 6. Submitting an ANSYS job. ...........................................................................................13 

Figure 7. GRD script for ANSYS job...........................................................................................13 

List of Tables 

Table 1. HPC MSRCs.....................................................................................................................4 
1

1. Introduction 

Access to the U.S. Army Research Laboratory Major Shared Resource Center’s (ARL-MSRC’s) 

computer facility from a desktop machine can be accomplished using a number of methods. For 

example, from a Unix* or Linux†

 workstation with the Kerberos‡ client installed, a High 

Performance Computing (HPC) ticket can be requested from the command prompt. Once your 

credentials have been established, an Xterm§ client can be made from your local display to the 

HPC host. On the other hand, the procedure from a Microsoft Windows PC platform is a little 

different. The user must load a stand-alone Kerberos client on the machine. Once done, the user 

can request tickets from an HPC asset using a small client window. After a ticket has been 

granted, the local host provides a Kerberos File Transfer Protocol (FTP) and Telnet graphical 

user interface (GUI). If an Xterm client is installed on the Microsoft Windows machine, then the 

machine operates much the same way as the Unix/Linux platform does through Xterm. Without 

an Xterm client, the user is limited to DOS-style FTP and Telnet** to interact with the HPC 

resources. Both systems have one drawback, the need to know a certain amount of Unix-based 

commands or antiquated DOS commands. Additionally, as systems come and go and procedures 

for submitting program-specific jobs change, users are forced to learn and relearn command 

procedures to use HPC for their computation needs. A solution to this constant flux is to write a 

platform-independent GUI to allow users to interface with HPC through an intuitive “point-andclick” environment. This eliminates the Scientist and Engineers’ (S & Es’) time-consuming task 

of learning new Global Resource Direction (GRD)†† procedures or changes on the system and 

puts the onus on HPC personnel to keep the interface to HPC current for users. It also puts the 

burden of providing support and keeping the GUI up to date where it belongs, on HPC personnel. 

An obvious GUI environment would be a Web page. Web pages by definition provide platform 

independence. The Web offers a platform-independent GUI by definition: the user interface 

runs in a standard browser (Internet Explorer or Netscape Navigator) using standard Internet 

technologies with no additional client software required. Furthermore, using a portable 

 * Unix is an operating system developed by Bell Laboratories in the early 1960s and is still regarded as an industry standard 

around the world. 

†

 Linux is a Unix-type operating system originally developed by Linus Torvalds with assistance from others. The source code 

is freely available to all. 

‡ Kerberos is a network authentication protocol. It is designed to provide strong authentication for client server applications

by using secret key cryptography. The protocol can be downloaded at the Massachusetts Institute of Technology or at 

<http://web.mit.edu>. 

§ The “xterm” program is a terminal emulation for the X-Window System and provides compatible terminal emulation similar 

to a DEC VT 100. 

** Telnet is a terminal emulation program for TCP/IP networks such as the Internet. TCP is responsible for verifying the 

correct delivery of data from client to server. IP is responsible for moving packets of data from node to node. 

†† GRD is a program to help users submit jobs to the High Performance Computing Computers at ARL and elsewhere. 
2

development language like Java would enable the GUI to be moved from server platform to 

platform as new systems are brought on line and older systems retired without redeveloping the 

HPC GUI. Because this is one obvious solution, other organizations have been developing or are 

developing approaches along similar lines. For example, the University of Minnesota has 

developed a Web interface to help users access their mainframe computer systems. The 

University of Minnesota’s Web interface was named Teraweb. Teraweb offers a Web interface 

to the University’s mainframe computers but is not written in Java and does not currently support 

GRD or a Kerberos interface in an open-source programming environment. Implementing 

Teraweb was possible, but with modification and additional costs and fees. Teraweb is not open 

source and is proprietary. Rather than be locked into someone else’s program environment, it 

was desirable to create a vanilla open-source security package that could be used throughout the 

MSRC computer infrastructure for site-specific applications. Therefore, it was decided that 

Teraweb was not the solution for ARL-MSRC. 

2. Approach 

There are two basic approaches to the security feature of the Gateway server that can be taken. 

A brief description of the two methods is given here and the advantages and disadvantages are 

discussed as well (figure 1). 

Figure 1. Gateway server approach schematic. 

The first approach is purely a Web page connection. In this approach, the user connects to a 

server using a Secure Socket Layer (SLL) connection. Then, using the SLL connection, the user 

authenticates, using Kerberos encryption, and gets Kerberos tickets to use in connections with 

HPC. The Web page provides a number of point-and-click GUIs layered on top of this basic 

authentication feature. Any number of applications or additional GUIs can be layered on top of 

this basic secure connection to provide HPC users easy access to HPC assets. The advantage of 

this approach is in its simplicity. Anyone can write GUI modules to be used with the basic 

security package. The other advantage is that it’s a Web page. Hence, it will work on a Unix 
3

platform or with a PC environment.* However, the approach has its drawbacks. The hyper text 

markup language (HTML) interface provides only a relatively few simple widgets (buttons, text 

areas, text fields, checkboxes, etc.) to build GUI interfaces. Advanced functionality (such as 

interactive remote visualization) requires more sophisticated clients. Other problems include 

aggravating missing functionality in current browsers. For example, the hyper text transfer 

protocol (HTTP) allows for multiple file uploads and downloads, but neither Microsoft Internet 

Explorer nor Netscape Navigator support this. Multiple file transfers are a desirable feature for 

HPC users who often need to perform recursive directory transfers. This restriction can be 

overcome by using signed Java Applets, but will not work on machines where users don’t have 

local privileges. 

The second approach uses the Kerberos tickets on the local machine and creates a connection 

between a PC machine and a server, which then connects to HPC. However, this methodology 

requires that software be loaded on the local user’s machine.† The advantages to both of these 

approaches is the platform independence. Platform independence is based on the use of Java as 

the primary language and the Apache Web server. Java offers a huge suite of functions and ease 

of portability. The drawback to this approach is that once again this requires that users are 

allowed to load software on their machines or the user will be required to have an administrator 

set up and maintain his computer with current copies of the software, which is not a bad option. 

Rather than picking and proceeding with one approach over another, both approaches described 

here were adapted and used as required to develop specific GUI applications for users. The first 

approach was developed initially because it required no additional effort on the part of the user. 

GUIs were created to allow users a basic point-and-click file transfer system from the PC to 

HPC. Additionally, modules have been written to allow users to submit jobs in ANSYS,‡ 

ZNS-Flow,§ and Fluent** to HPC for simulation. This user interface writes a basic GRD script 

for the job submittal and allows users the option to modify the script or accept it as is. The script 

generation service that we provide is actually general in nature and can be extended to support 

other queuing systems such as LSF†† and PBS.‡‡ This is not important for the ARL MSRC but is 

an important issue for deployment at additional MSRCs and for supporting users that have 

 *

 A personal computer environment might include Microsoft Windows 95, 98, ME, NT, 2000, or XP, as well as Linux and 

Apple Computers Macintosh operating systems. 

† The current approach is to use Java routines to build functionality. Java offers a platform-independent, free programming 

language with a lot of functionality already built in. Java JDK1.4 is currently being used for the development of users’ HPC 

GUIs. 

‡ The ANSYS suite of programs provides state-of-the-art prediction capabilities for structural, thermal, mechanical, 

computational fluid dynamics (CFD), and electromagnetic analysis of structures and systems. ANSYS software provides 

accurate modeling of physical phenomenon using accepted mathematical techniques. 

§ ZNS-Flow is based on Chimera technology and allows the computational predictions of fluid and air flow problems. This is 

considered a CFD code. 

** Fluent is a commercial software package for solving fluid flow problems in computational fluid dynamics on CFD. 

†† LSF load-sharing facility is a suite of workload management products from Platform Computing Corporation. 

‡‡ PBS Portable Batch System is a flexible batch queuing and workload management system by Veridian Systems for the 

National Aeronautics and Space Administration. It works on networked UNIX platforms. 
4

accounts both at ARL and other MSRCs. Additionally, the process is stored in a session that can 

later be modified and resubmitted for further analysis. The GUI also provides a basic procedure 

to check on running jobs, jobs in the queue, and to delete these jobs if necessary. 

The next step in this process is for the developers of the interface to work with HPC users and 

build in functionality to the specific application to help ease the use of HPC assets for U.S. 

Army-related research. Because the program is open source and was written using Java and Java 

Server Pages (JSP) this process can continue with any developer at any of the MSRC sites and be 

adapted to the specific needs of a specific organization. One final note is that the servers running 

the software developed for this GUI require administrative maintenance. This benefits the user 

in putting the onus of HPC access on the administrator rather than the user. The administrator 

needs to maintain the system, the GUI, and update procedures as new machines and software 

continually roll out, while older systems and software are retired. 

3. Functionality 

The target market of Gateway* is the S & Es at any of the HPC facilities. Table 1 lists the 

location of these facilities. 

Table 1. HPC MSRCs. 

ARL ASC 

U.S. Army Research Laboratory 

ARL MSRC 

ATTN: AMSRC-CI-HA 

Aberdeen Proving Ground, MD 21005-5006 

Aeronautical Systems Center 

ASC/HP Building 676, Area B 

2435 Fifth Street 

WPAFB, OH 45433-7802 

ERDC NAVO 

U.S. Army Engineer Research and Development Center 

CEWES-IH 

3909 Hall Ferry Road 

TL112, Room 207 

Vicksburg, MS 39180 

Naval Oceanographic Office/MSRC Program 

1002 Balch Boulevard 

Stennis Space Center, MS 39522-5001 

The functionality of the web portal includes the following: 

• Secure login and access to HPC assets. Users will use their user name, password, and 

secure IDs over a Kerberos connection to a server using one of the two methods described 

in section 2. 

• A master page will be maintained that connects to additional services and functions at 

various sites within the MSRC.

 *

 “The Gateway Computational Web Portal” is a journal article describing the system, and “Gateway Security Infrastructure” 

provides additional material on security, including alternative strategies for secure Web access. It also provides a more in-depth 

discussion of WebFlow. 
5

• A server running Apache* and Tomcat† will be used with JSP and Java programs to 

serve up HTML pages to clients logging on. Connections will be made through a proxy 

server on the World Wide Web to the Gateway server located behind an MSRC 

firewall. 

• Batch script generation with a GUI interface will enable users access to HPC computers 

and run simulations on a variety of software packages. Currently, Gateway supports 

ANSYS, ZNS Flow, and Fluent. 

• File transfer services are provided on several levels as described in the approach using 

HTML protocols and Java-signed Applets. 

• Job monitoring will be allowed through the Web portal. Additionally, a job can be 

deleted while in the queue and stopped through this interface. 

• The portal’s Web interface can easily be extended to link to existing ARL Internet 

resources, such as code documentation and the ARL machine load status pages. 

Future efforts will enable the following: 

• Additional GUI interfaces for applications requiring HPC resources. Examples include 

CTH,‡ DYNA,§ Paradyn,** and other resource-intensive software applications. 

• A Kerberized VNC†† connection to an HPC graphics workstation. 

• Access between MSRC sites. 

• File transfers between HPC mainframe computer workstations and user PCs. (Connect 

one location transfer anywhere.) 

4. The Gateway Portal 

Gateway architecture will initially consist of a three-tiered approach to security. This will 

eventually be replaced by a four-tiered system. Both will be discussed here. The first layer 

 *

 Apache is an open-source software product that serves as a web server platform on numerous operating systems. 

† Tomcat is the servlet container that is used for the implementation of Java Servlet (1, 2), and JSP. Simply put, Tomcat 

is the server-side software that interpolates JSP (3, 4), and generates HTML code for the World Wide Web. 

‡

 CTH 3-D Eulerian Shock Code was developed by Sandia National Laboratories and can model multi-phase, elasticviscoplastic, porous, and explosive materials. 

§ DYNA is a general purpose explicit nonlinear finite element code developed by Halquist et al. for the Department of 

Energy. 

** Paradyn is an implementation of the DYNA 3-D code optimized for parallel processing. 

†† Virtual network computing provides a remote display system that allows one to view a computing desktop 

environment anywhere on the Internet and for a wide variety of machines. VNC was developed by AT&T. 
6

of the three-tiered system consists of dynamically generated Web pages. These are 

implemented using JSP that allow Java code to be embedded into an HTML page (figure 2). 

Therefore, the code that is executed on the client’s machine is HTML based. 

Figure 2. Gateway architecture. 

In figure 2, the user interacts with the Apache server through an SLL-encrypted connection. 

Services are either implemented within JavaBean components in the Web server’s servlet 

engine or by WebFlow modules. Communication between child servers and their parent uses 

the secure SECIOP protocol. Communications with backend resources use Kerberized rsh 

and rcp. 

The middle tier represents the control layer and consists of two subtiers. The first subtier 

consists of an Apache Web Server and a servlet engine (Tomcat, also from Apache). The 

Tomcat server compiles and executes Java code contained in the JSP pages. Most of the 

functionality (such as security and session management) is encapsulated into JavaBean 

components rather than in the JSP pages themselves. These components are simply added to 

the pages. All of the JavaBean components run in the same servlet engine (a Java Virtual 

Machine) on the same host machine as the Apache web server. These components can 

provide services themselves, or they can act as proxies to WebFlow components (described 

next). 
7

The second part of the middle tier consists of the distributed application layer, implemented 

using WebFlow, originally developed by Dr. Geoffrey Fox’s group at Syracuse University 

and partially funded by the High Performance Computing Modernization Program (HPCMP) 

through programming environment and training (PET). WebFlow uses CORBA* to allow 

components to be distributed over multiple hosts. That is, components can be contained in 

other servers running on different machines besides the Apache host server. WebFlow 

components (or modules) implement services such as job submission and file transfer and can 

be extended to provide other services. WebFlow servers are hierarchical, so a single master 

server acts as the parent and gatekeeper server for the distributed children. Clients (in this 

case, a JSP page) do not contact child servers directly, but instead contact the parent server 

and request child servers by name. The parent then forwards requests to the appropriate 

child. 

The final layer in the system is the HPC layer. This is a Unix layer that will be accessed 

through the middle tier. Commands in Unix will be scripted and issued from the middle tier 

using the user’s credentials. The HPC layer has functionality like GRD already built into the 

system. Therefore, this functionality will be leveraged by the Gateway GUI. This allows the 

client to pay attention to the task at hand (getting CPU cycles for his simulation) rather than 

worrying about GRD updates or changes to the bottom layer configuration.†

 As new systems 

come on line, modulus at the center tier will be upgraded to improve Gateway functionality. 

The four-tiered system will work the same way as the three-tiered system except the Web 

server and servlet engine will be behind a firewall. These will be accessed through a proxy 

server outside the firewall. This added layer of security prevents potential would-be intruders 

from knowing the Internet protocol address of the machine where Gateway is installed. 

5. Security Model 

As seen in figure 2, Gateway requires several layers of security: 

(1) The browser must make a secure connection to the Web server. 

(2) The JSP pages must make a secure connection to the WebFlow parent server. 

(3) The WebFlow parent and child servers must have a secure connection. 

(4) WebFlow connections to the back end (such as HPCs) must be secure.

 *

 Common Object Request Broker Architecture (CORBA) is an open distributed object infrastructure being standardized 

by the Object Management Group (OMG) (5). 

† The HPC facility is constantly undergoing upgrades and improvements to their systems. For example, older Silicon 

Graphics Incorporated (SGI) equipment is being replaced by newer IBM CPUs this year. These changes can effect the way 

users submit and run jobs on the machine. By creating this portal, the client’s environment becomes stable and the burden of 

staying up to date is placed on HPC personnel. 
8

We address the following security issues: authentication, authorization, privacy, and data 

integrity. We built the first two on top of the existing Kerberos security infrastructure at the 

MSRCs, and the last two are subsumed by encryption mechanisms (6). 

A portal administrator starts the Apache, Tomcat, and WebFlow master servers. Presumably, 

this will be done in a special “Gateway” account, and we will assume that these servers run 

under that account. These accounts are checked and maintained as a system administration 

function within HPC. The server machine may or may not include network file system 

(NFS)-mounted directories and is assumed to be able to reach HPC machines and mass 

storage via Kerberized rsh and rcp. It will be assumed that the administrator has a 

forwardable Kerberos ticket. For production portal use, this ticket should be renewable via a 

cron job. The Apache server is set up to support SLL-encrypted logins using 128-bit 

encryption. This server was built using OpenSSL and ModSSL. 

Users log in to the portal via a login page that prompts them for their principal name (such as 

swilker or pierceme@asc.hpc.mil), password, and passcode. When the user submits this form 

(via HTTP POST) the server runs a kinit on the remote system and creates a ticket for the 

user. The ticket is stored in /tmp and will be named krb5cc_<principal_name+timestamp> 

(the time stamp guarantees the ticket name is unique). A simple Expect script is used to run 

the kinit on the server. 

One of the features of servlet engines, such as Tomcat, is that they maintain session states for 

users automatically. When a user accesses a particular Tomcat server (indirectly, through 

Apache), a session cookie is generated for him. Tomcat uses this cookie to maintain session 

state for the user; so for example, JSP pages requiring extensive initialization will only need 

to be initialized once per session, and user interactions can be stored in memory. Session 

lifetime is configurable, but typically lasts about 2 hr. We will take advantage of this built-in 

feature of Tomcat to support user authentication and identification, as we now describe. 

We have developed a special authentication component to manage user session tickets. Our 

mechanisms are based on the ideas of Kelly Kirk (ARL PET Enabling Technologies On-Site 

Lead) that have been previously reviewed by the HPCMP (6). The authentication component 

is included in all Gateway JSP pages. When the user logs in and successfully gets a ticket, a 

unique HTTP cookie is created for him. This cookie is a message digest (using an MD5 

algorithm) of the contents of his ticket file. Any subsequent access to Gateway Web pages is 

verified by comparing this encrypted cookie to the value stored in memory on the server. 

Additionally, the IP address of the user’s Web browser is stored in memory. Subsequent 

page requests are verified to come from the same IP address as the initial request used at 

login. 

Users may also manage their sessions through the browser by deleting their session 

credentials. This will remove the session ID and IP addresses stored on the server, delete the 
9

user’s Kerberos credential from the file system, and set the ticket-based session cookie’s 

lifespan to zero (causing immediate expiration). The session credentials will also be deleted 

automatically if the session expires (say, in 2 hr) and the user will need to log in again to 

access the Gateway Web pages. Session credentials for all users will be deleted if the 

Tomcat server is shut down. 

In summary, the Gateway pages can only be accessed if the user has performed a successful 

kinit. Thereafter, the user is identified by a unique Tomcat session cookie, a unique session 

cookie generated from his ticket granting ticket (TGT), and the IP address he used to initiate 

the session. All Web access is encrypted. We can also require the browser to send a properly 

signed client certificate as an additional means of identification. 

For this application, JSP pages make use of services provided by WebFlow servers. The 

WebFlow servers use CORBA Object Request Brokers (ORBs) for remote client-server 

connections. The CORBA security service is a general set of interfaces for making these 

client-server connections secure, and these services can be built using different security 

mechanisms. We use the ORBAcus* ORB from Object Oriented Concepts in WebFlow and 

have purchased a security service extension that uses Kerberos from Adiron Software. 

In Gateway, JSP pages act as clients to the WebFlow servers. Both the JSP client and the 

WebFlow server are required to have valid credentials. For the JSP pages, this is the TGT 

created when a Gateway administrator logged in to the account. The WebFlow parent server, 

which runs on the same machine as the Apache and Tomcat servers, must access a keytab 

file. The Kerberos implementation of CORBA security requires that all Kerberos services 

use a keytab for authentication. For testbed implementations of Gateway, we have used 

specially generated keytab files that are owned by the Gateway account and are tied to a 

single server machine. 

WebFlow servers can potentially be distributed on multiple machines as child servers to the 

parent. Wire communication between the servers goes over SECIOP, a secure CORBA 

protocol that supports generic security services application programming interface 

mechanisms such as Kerberos. SECIOP supports Data Encryption Standard (DES)†

encryption and MD5 hashing. These child servers are required to possess access to a keytab 

file and must authenticate themselves to the parent. These servers would also need access to 

keytab files. We do not currently make use of this feature with the ARL Gateway server. 

Interactions with any remote machines are handled through Kerberized rsh and rcp. For 

example, if the queuing system of a remote machine needs to be queried to learn a job status, 

a WebFlow module runs the qsub command through rsh as an external call.

 *

 ORBacus is a fully CORBA-compliant ORB that is distributed as source code. ORBAcus is a product of Object 

Oriented Concepts, now owned by Iona Software. See <www.ooc.com>. 

†

 DES Encryption originally published in 1977 with the official backing of the U.S. government. 
10

Job submission is handled in the following manner: When a user logs in to the Web server, a 

TGT is generated for him on the server. This file is owned by the Gateway account. The 

user’s identity (principal name) is maintained as part of his/her session (as described 

previously). When the user wishes to submit a script to a particular queuing system, the 

server does this as a remote process with the environment variable KRB5CCNAME set to the 

appropriate credential. Thus the user’s credential is owned by the Gateway account, but the 

job is submitted as the user’s. 

Other services may be handled in the same manner. For example, the user’s file system 

might be accessed through an rsh command to determine the files in his/her directory. The 

user may move files between different remote machines using rcp, with ownership preserved. 

Files transferred between the user’s desktop and the server machine are handled in a different 

manner, using encrypted HTTP upload and download mechanisms, following proper Web 

authentication previously described. 

We finally note that WebFlow servers may accomplish these same tasks directly. For 

instance, by the same process just described, the master server can create a WebFlow child 

process via rsh that will run as the appropriate user. This process could then access the user’s 

file system as needed, submit jobs, etc. 

6. Gateway GUI Interface 

The Gateway Interface consists of several screens that are reviewed here. The basic “look” 

and “feel” can be changed or updated at any time. The GUI starts a session with an HTTP 

login screen as shown in figure 3. 

In the top box, the user inserts his/her user name and the realm that he/she wishes to 

authenticate as well (e.g., swilker@arl.hpc.mil). That is followed by a password and then the 

authentication ID from the user’s SecureID card. The server authenticates the user and 

creates a ticket for the user on the realm that the user has permission to be on. 

After some initial screens with the message of the day, the screen shown in figure 4 appears. 

This screen consists of a “submit job” button, an “archive” button, and a “portal admin” 

button. Along the top of the window, there are buttons for a file browser and a job monitor; 

these buttons are also repeated along the left-side frame. The buttons along the top provide 

the user with a new independent window. The buttons along the side do the same function 

but use the existing frames’ main window. A logout window is also provided to allow the 

user to exit the session and kill his/her tickets. The file browser feature provides a connection 

between the user’s machine and HPC storage. The user can then transfer files to HPC from
11

Figure 3. Login screen. 

Figure 4. Main screen. 

his/her local machine and retrieve files from HPC to his/her local machine. There are plans 

to extend this capability, and this will be discussed in the conclusion section. The Job 

Monitor feature queries HPC GRD for jobs that are currently submitted. All of the jobs in the 

queue are then displayed. The user is additionally allowed to delete a job from the queue or 

stop a job. 

The job submission module is designed to allow other sites and users the ability to add 

software to the access list, write their own scripts, and customize the job submission process. 

The current portal includes modules for three different codes. These are ANSYS, 

ZNS-FLOW, and Fluent. A snapshot of the screen is shown in figure 5. 
12

Figure 5. Submitting jobs. 

For each of the options available, a problem name is supplied, and the script will create a 

directory on the user’s HPC home directory with that name and a date as part of the name. 

The GRD scripts program input files and output files are all stored there. Then, using the 

archive feature, the user can easily return to the same job again after, for instance, he/she 

changes the input file. This allows users to correct mistakes and quickly resubmit jobs to 

HPC for simulation. A job submission using ANSYS is shown in figure 6 for reference. 

In this screen, the user selects the wall time for the run and the complex, although not 

currently working, so anything will work here (e.g., SGI, an input file, and an output file). 

The script then writes a GRD script and supplies it via an editable text window. This can be 

changed by the user or used “as-is” to submit the job. 

Figure 7 shows a cut-in-half view of the GRD script in a text window. After you submit the 

job, you can check on the job’s progress using the job monitor. Jobs can be stopped and then 

resubmitted using the archive feature. The procedures followed here will vary between 

different application software packages. However, the functionality remains the same, i.e., 

(1) the user authenticates and gets a Kerberos ticket, (2) files are moved between the user’s 

machine and HPC machine using the interface, (3) a series of questions, pertaining to the 

running of an application, are answered using some GUI interface, and (4) the user submits 

his/her job through the GRD interface using the script provided. 
13

Figure 6. Submitting an ANSYS job. 

-------------------------------------------------------------------------------------------------------- 

Figure 7. GRD script for ANSYS job. 

7. Conclusions 

An open-source vanilla Kerberos-enabled Web portal now exists in which a user can transfer 

files and submit computer runs to the HPC. The system is open source and can be adapted 

for use at any of the HPC sites and elsewhere. The portal will only be viable if users who 

need this HPC capability are identified and then the developers work with the users to make 

the interface user friendly. The advantage to having this relationship is obvious. For starters, 

the client buys into the system, but more importantly is the fact that the developers don’t 

usually know the user’s needs or wants. The user knows his code and knows what will help 
14

him do his/her work more efficiently. At the same time, the developers have knowledge of 

the HPC architecture and can smooth over the coding difficulties to provide HPC with an 

interface that everyone is happy with. The marriage between the two sciences is a good one. 

Future efforts will include a Kerberos VNC and a more robust version of the FTP. The VNC 

will allow users to access an HPC or science visualization computer, as if he/she were setting 

in front of it. The implementation of this feature will avoid the need for users to physically 

walk to other sites to complete their work. Another big advantage is that files can be left on 

one machine and accessed without time-consuming file transfers. Additionally, the user gets 

the advantage of using a powerful machine with lots of high-end graphic capabilities without 

the burden of purchasing expensive hardware and software. The file transfer feature will also 

be enhanced. Currently, file transfers can be done within the Unix environment on HPC. 

However, this is a command line driven procedure. With this interface, the user will be able 

to drag and drop whole directory structures using Java-signed Applets from one system to the 

next, thus greatly simplifying the process of pre- and post-processing. The Web interface 

will include this feature. Additionally, there will be a Java stand-alone program that will also 

provide the same functionality using a local machine’s HPC Kerberos tickets. The advantage 

of the stand-alone program is in its use of the local Kerberos authentication. The 

disadvantage is that the users will need to have the current version of Java JDK library 

installed on the local machine to make the program function properly.
15

8. References 

1. Flanagan, D. Java in a Nutshell; O’Reilly Press: California, 2002. 

2. Fields, D. K.; Kolb, M. A. Java Server Pages; Manning Press: Connecticut, 2000; 

Java is an open-source programming language provided by SUN Microsystems. See 

<http://www.sun.com>. 

3. Monson-Hafel, R. Enterprise Java Beans; O’Reilly Press: California, 2001. 

4. Tremblett, P. Instant Java Server Pages; McGraw-Hill Press: New York, 2000. 

5. Adiron LLC implements the CORBA security service in Kerberos: <www.adiron.com>. 

6. Marlon, P. Gateway Security Model; White Paper ASC-MSRC; University of Indiana, 

IN, 2002. 
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