Electrical computers and digital processing systems: multicomput – Computer network managing – Network resource allocating
Reexamination Certificate
1997-06-11
2001-06-05
Harrell, Robert B. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Computer network managing
Network resource allocating
C709S226000, C709S229000
Reexamination Certificate
active
06243751
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to computer software, and more specifically to client-server computer software.
BACKGROUND OF THE INVENTION
Where a single repository of data is shared by many users, a client-server architecture may be employed. Referring now to
FIG. 1
, four computers
110
,
112
,
114
,
116
arranged using a client-server architecture are illustrated. In a client-server architecture, a server
110
is used to access a data repository storage device
102
that stores the data that is shared among the clients
112
,
114
,
116
. Users of the client-server system
100
use a client
112
,
114
or
116
to communicate with the server
110
to access the shared data stored in the storage device
102
. Clients
112
,
114
,
116
do not have direct access to the data in the storage device
102
, but may request that the server
110
perform actions such as performing retrievals using queries, or adding to or changing the data stored in the storage device
102
.
Each client
112
,
114
,
116
is coupled to the server
110
by a connection
122
,
124
,
126
between the clients
112
,
114
,
116
and the server
110
. Each connection
122
,
124
,
126
may be physically separate as shown in
FIG. 1
, or may be shared using a local area network, or LAN. Ports
142
,
144
,
146
and associated cabling connected to each of the clients
112
,
114
,
116
provide the OSI layers
1
and
2
connectivity to the ports
132
,
134
,
136
of the server
110
. If the server
110
will communicate with each client
112
,
114
,
116
over a LAN, a single LAN interface port may physically replace ports
132
,
134
,
136
, and ports
132
,
134
,
136
are treated as logical ports.
Referring now to
FIG. 2
, the conventional server
110
of
FIG. 1
is shown in more detail. A server
110
may be built from conventional server software
210
that runs using a conventional operating system
212
on a conventional computer system. A SparcCenter 2000 running the Solaris operating system commercially available from Sun Microsystems of Mountain View, Calif. is one computer system and operating system that may be used, among others. Server software
210
may be conventional database server software such as the Oracle7 product commercially available from Oracle Corporation of Redwood Shores, Calif., or other types of server software.
Referring now to
FIGS. 1 and 2
, each client
112
,
114
,
116
communicates with the server
110
by establishing a connection
122
,
124
or
126
between the respective client
112
,
114
or
116
and the server
110
. Each connection
122
,
124
,
126
is established through conventional data communications means, controlled on the server
110
by the server operating system
212
. Each client
112
,
114
,
116
may establish and maintain one or more simultaneous connections to the server
110
depending on the capabilities of the operating system
212
and the physical capabilities of each client
112
,
114
,
116
and the server
110
. When a connection is established, conventional server software
210
establishes a process to handle communications over the connection and to execute commands received, and maintains information about the process during the period in which the connection is maintained. The process is associated with the port
132
,
134
or
136
that was used to establish the session, and all communications received from that port
132
,
134
or
136
are routed to that process by the operating system
212
, the server software
210
or both.
To allow a user to access the data in the server
110
from any client
112
,
114
,
116
, the user establishes a session with the server
110
, by identifying himself to a client
112
,
114
or
116
, for example, by using a user identifier and password. The client
112
,
114
or
116
passes this information to the server
110
. Using its software
210
, the server
110
checks an access table
218
maintained by a database administrator for validity of the user identifier and password, and if valid, a session is established by the server
110
. For each port
132
,
134
,
136
over which a process of the server software
210
and a session of the user has been established, the server
110
maintains data about the session in a session data storage
232
,
234
or
236
in a storage device such as a memory or hard disk. The session data storage
232
,
234
or
236
may contain the user identifier and state information for the database, such as instances of object types, language and character set data, statistics about resource usage for the session, storage for cursors and variables and other information. Subsequent commands received by the process over a port
132
,
134
,
136
are assumed by the server
110
to come from the user that last established a session via that port until such session is terminated. In this manner, the session, process and port
132
,
134
or
136
are associated with each other. The process looks to the data in the session data storage
232
,
234
or
236
corresponding to the process to execute the commands it receives. When the user logs out, the process is terminated and other users may log into the server using the same port as was previously used, establish a connection, process and session on the server
110
and send commands to the server
110
for execution.
The server software
210
may limit access to the information it serves based on the user identifier stored in the session data storage
232
,
234
or
236
corresponding to the process accepting the command. For example, a user of conventional database server software
210
may have no access to one set of data, read-only access to a second set of data, and read and write access to a third set of data. The server software
210
manages the access to the data stored in the storage device
102
by comparing the user identifier stored in the session data storage
232
,
234
or
236
for the process with data stored in an access table
218
defined and maintained by a database administrator that identifies to which data each user or groups of users have access, and the type of access, read only or read and write access.
Each connection
122
,
124
or
126
between the server
110
and the clients
112
,
114
or
116
requires resources on the server
110
such as memory to manage the process and the connection
122
,
124
or
126
associated with the session. Even a user that maintains a session without requesting the server to perform any action uses these resources. In order to conserve these resources, some conventional operating systems
212
running in the computer that runs the server software
210
impose a limit on the number of connections
122
,
124
,
126
that may be simultaneously maintained. Other conventional operating systems
212
may not impose a limit on the number of such connections
122
,
124
,
126
, but a large number of connections
122
,
124
,
126
over which sessions are established can hinder the other processes on the server
110
which have to run using the remaining resources.
Some users that do not perform many transactions with the server
110
may wish to have the client
112
,
114
,
116
that they use continuously maintain a session with the server
110
even during periods during which they will not be communicating with the server
110
, because it is cumbersome or expensive to establish a connection with the server
110
, thus establishing the session takes time and resources that the user may wish to expend no more than once each day. Because such users utilize resources of the server
110
maintaining the session and the associated process and connection, they may either prevent other users from accessing the limited number of connections allowed by the operating system
212
, or needlessly tie up resources of the server
110
, reducing resources available to the other active or potential users of the server
110
.
TP monitors have been developed to allow more users to use a server
110
than the number of
Bellemore John
Chatterjee Debashish
Jasuja Amit
Gotlieb Charles E.
Harrell Robert B.
Oracle Corporation
Willett Stephan
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