Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
2001-09-25
2004-02-03
Mizrahi, Diane D. (Department: 2175)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000
Reexamination Certificate
active
06687702
ABSTRACT:
COMPUTER PROGRAM LISTING APPENDIX
This application includes a transmittal under 37 C.F.R. §1.52(e) of a Computer Program Listing Appendix comprising duplicate compact discs (2), respectively labeled “Copy 1” and “Copy 2”. The discs are IBM-PC machine formatted and Microsoft® Windows Operating System compatible, and include identical copies of the following list of files:
File Name
Created/Last Modified
File Size (KB)
Source Code.txt
Sep. 25, 2001
224
All of the material disclosed in the Computer Program Listing Appendix is hereby incorporated by reference into the present application.
COPYRIGHT NOTICE
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to distributed (e.g., three-tier) computing systems and, more particularly, to a system and methods for improving data access and operation in distributed computer environments.
2. Description of the Background Art
Today, most computers are linked to other computer systems via a computer network. Well-known examples of computer networks include local-area networks (LANs) where the computers are geographically close together (e.g., in the same building), and wide-area networks (WANs) where the computers are farther apart and are connected by telephone lines or radio waves.
Often, networks are configured as “client/server” networks, such that each computer on the network is either a “client” or a “server.” Servers are powerful computers or processes dedicated to managing shared resources, such as storage (i.e., disk drives), printers, modems, or the like. Servers are often dedicated, meaning that they perform no other tasks besides their server tasks. For instance, a database server is a computer system that manages database information, including processing database queries from various clients. The client part of this client/server architecture typically comprises PCs or workstations that rely on a server to perform some operations. Typically, a client runs a “client application” that relies on a server to perform some operations, such as returning particular database information. Often, client/server architecture is thought of as a “two-tier architecture,” one in which the user interface runs on the client or “front end” and the database is stored on the server or “back end.” The actual business rules or application logic driving operation of the application can run on either the client or the server (or even be partitioned between the two). In a typical deployment of such a system, a client application, such as one created by an information service (IS) shop, resides on all of the client or end-user machines. Such client applications interact with host database engines (e.g., Sybase® Adaptive Server®), executing business logic that traditionally ran at the client machines.
More recently, the development model has shifted from standard client/server or two-tier development to a three-tier, component-based development model. This newer client/server architecture introduces three well-defined and separate processes, each typically running on a different platform. A “first tier” provides the user interface, which runs on the user's computer (i.e., the client). Next, a “second tier” provides the functional modules that actually process data. This middle tier typically runs on a server, often called an “application server.” A “third tier” furnishes a database management system (DBMS) that stores the data required by the middle tier. This tier may run on a second server called the database server.
The three-tier design has many advantages over traditional two-tier or single-tier designs. For example, the added modularity makes it easier to modify or replace one tier without affecting the other tiers. Separating the application functions from the database functions makes it easier to implement load balancing. Thus, by partitioning applications cleanly into presentation, application logic, and data sections, the result will be enhanced scalability, reusability, security, and manageability.
Three-tier database systems are well documented in the patent and trade literature; see, e.g., U.S. Pat. No. 6,266,666, entitled “Component transaction server for developing and deploying transaction-intensive business applications,” the disclosure of which is hereby incorporated by reference.
In the three-tier model, communication must occur among the various tiers, such as from a client to a middle tier, and from the middle tier to a back-end database. A multitude of message traffic or communication flows between the client and the database, with the middle tier positioned in between. One of the advantages of employing a middle tier is to pool together connections to the database in a central (middleware) tier, thus allowing more efficient access to the database. In particular, database connections, which are expensive in terms of system and network resources, are cached in the middle tier.
Another advantage of the middle tier is to offload certain computations from the back-end database, particularly those pertaining to business logic (i.e., business objects). Exploiting this advantage, a system administrator would deploy a middle tier on a separate server computer, one that was physically separate from the computer hosting the back-end database. More recently, however, hardware vendors have released more powerful computers such that both the middle tier and the back-end database may now easily run on the same host, a single physical computer. One such computer is Sun's StarFire computer (Sun Microsystems of Mountain View, Calif.); it employs 64 processors, running under a 64-bit operating system, with access to a 64G memory space. As a result of this more powerful hardware architecture now available, the approach of deploying a middle tier on a separate physical computer is no longer a necessity. In some instances, it may be more cost effective to deploy and maintain the middle tier and the back-end database on the same computer.
Typically, any business logic modeled on a middle tier requires significant, if not substantial, access to the back-end database. For example, SQL queries may be passed from the middle tier to the database, with corresponding result sets being returned back to the middle tier (and then onto the relevant client). If a particular query result is large, a corresponding large data set (and accompanying messages) must be transmitted back to the middle tier. Therefore, in a classic configuration, where a middle tier exists on a separate machine, a lot of network communication occurs between the middle tier and the database. In the instance where the middle tier and database reside on a single computer, physical (e.g., Ethernet) network traffic is avoided. However, the communication process is still resource intensive, as the underlying communication protocol stack (e.g., TCP/IP) is still used to effect communication between the middle tier and the database. Accordingly, system performance is negatively impacted.
Another disadvantage that comes to light is of the potential for breach of security. Even when the middle tier and database are on the same physical machine, it is still possible for an unauthorized individual to gain access to the communications occurring between the two. Again, this results from the underlying communication protocol stack employed to effect the communication. Although the communications may be encrypted (e.g., using SSL, Secured Socket Layer), such encryption adds additional overhead to the system, thus impacting overall system performance.
To date, attempts to address the foregoing problems have focused on optimizing network communication. For example, using a “loop back” optimization, com
Fatemi Taghi
Ghosh Prasanta
Vaitheeswaran Girish
Mizrahi Diane D.
Smart John A.
Sybass, Inc.
Wu Yicun
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