Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Least weight routing
Reexamination Certificate
1999-08-03
2003-12-16
Wiley, David (Department: 2143)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Least weight routing
C709S200000, C709S223000, C709S229000
Reexamination Certificate
active
06665701
ABSTRACT:
TECHNICAL FIELD
The present invention relates to communications networks and, in particular, to the exchange of data between users of computational resources connected to a communications network and a distributed resource allocator handling system that manages the use of those computational resources, including resolving contending requests for use of the computational resources.
BACKGROUND OF THE INVENTION
A typical communications network comprises a number of computers and other electronic devices interconnected by a data transmission network. Data transmission networks include public switched telephone networks (PSTNs), ATM networks, internal intranets, the Internet and private networks implemented using any of a large number of available software and hardware components. Commonly, a computer is connected to a physical data transmission network through one or more physical ports, each port having a unique network address. Additional types of electronic devices may also be directly connected to a physical data transmission network or may be accessed from the physical data transmission network through an intermediate computer to which the electronic devices are attached. These additional electronic devices include modems, printers, switchboards, and audio response units.
Each computer attached to the network can execute one or more software programs. An instance of a running program is called a process. A person using a general purpose computer normally launches the execution of application programs. Application programs include word processing programs, web browsers, spread sheets, and computer games. Such programs will be called “users” in the following discussion. Application programs can, in turn, request and make use of operating system services provided by concurrently executing operating system programs. These services include the transfer of data from one general purpose computer to another over a physical data transmission network. The data may be transferred to another application program running on a remote computer or to a peripheral device such as a modem or a printer. An application program may also initiate execution of a program on a remote computer, transmit data to that program, and receive data back from that program over a physical data transmission network. The electronic devices, including computers, that a user may directly request services from, either directly or indirectly through operating system calls, are commonly referred to as computer resources.
FIG. 1
represents a schematic diagram of a simple communications network. The physical data transmission network
101
is represented as a central spoke and hub feature connecting the remaining elements in the diagram. These remaining elements include computers
102
-
106
, users
107
-
110
, and resources
112
-
118
. One resource
112
is connected directly to the physical data transmission network. Resources
113
-
118
are indirectly connected to the network through computers. Tasks
111
,
119
, and
120
are processes running on a multi-tasking computer. Each task is launched by a user. The capacity of this multi-tasking computer
106
to run processes is considered a resource. Resources
112
-
118
represent printers, modems, switchboards, or other electonic devices.
A communications network, like the network displayed in
FIG. 1
, provides the potential for a user running on one computer to exchange data with, and request services from, remote resources connected to the network. For example, suppose computer
102
in
FIG. 1
represents a personal computer running a software application program corresponding to user
107
. Resource
113
, which is attached directly to this personal computer, represents a black and white laser printer. Resource
114
, which is directly connected to computer
104
, represents a color printer. Suppose that user
107
has been directed to print out a color diagram. In order to print the color diagram, user
107
must send to computer
104
, through the physical data transmission network, a file representing the diagram to be printed and a request that that file be printed out by the color printer
114
.
Even in a simple communications network, like the one displayed in
FIG. 1
, attempts by several users to simultaneously access remote resources can lead to a number of problems. Continuing with the above example, suppose user
109
running on computer
106
has also been directed to print a color diagram, and user
109
sends a request to computer
104
to print the color diagram on color printer
114
at about the same time as user
107
sends its request. In such a case, users
107
and
109
are said to contend for resource
114
. Some resources, such as color printer
114
, contain a queuing mechanism that resolves such contentions by queuing the requests in the order that they arrive. This means, however, that if user
107
made its request slightly ahead of user
109
, user
109
must wait until the request made by user
107
has been completed. Forcing user
109
to wait until user
107
relinquishes printer
114
may adversely affect user
109
's expected quality of service. For example, user
109
may be forced to wait for an extremely long period of time before having the request processed.
Suppose further that resource
112
is a high speed modem without a sophisticated queuing mechanism, and suppose users
108
and
110
have been simultaneously directed to transmit large data files using this modem to a remote computer accessible only over telephone lines. In this case the consequences of contention may be quite severe, resulting in garbled transmission or the failure of one or both of the computers to transmit their files. Such contention also raises the same quality of service issues discussed above.
Suppose further that resource
112
is a bi-directional high speed modem that may be accessed by users from both inside and outside a computer network. Thus, if user
110
attempts to access the high speed modem
112
from outside the network while user
108
tries to access the modem from inside the network, then at least one of these users will not gain access to this modem. Under some circumstances, it may be preferable for user
110
, the outside requester, to gain access to the modem
112
over user
108
, regardless of the order in which their respective requests arrive. Such contention problems are nearly impossible to solve at the application program level. Users must know which resources are accessible via the network and which resources are currently busy with other tasks. This further implies that the users have essentially global information about the entire communications network and the resources therein. Such global information is dynamic rather than static. Printers can be turned on and off, for instance, or additional resources can be added to the network. It is far beyond the capability of application programs to acquire and maintain dynamic global network information. Even if a particular application program could be written to acquire and maintain dynamic global information, every other software application program would also need to be written with this capability. Such redundancy is prohibitively expensive and inefficient. In the example of high speed modem
112
, both user
108
and user
110
would also need to be aware of each other and to constantly monitor the timing of each other's requests for modem
112
.
SUMMARY OF THE INVENTION
The present invention provides a method and system for exchanging data between a user and a distributed resource allocator handling system that allocates computer resources connected to a communications network to users requesting those resources. The distributed resource allocator handling system comprises a number of resource allocator system agents, each running as a separate process on a computer connected to the network. Each resource allocator system agent maintains a database of global network resource information and constantly communicates with all other resource allocator syste
Combs Charles
Gold Jeffrey
Mair Brian
Pedersen David
Schear David
Avellino Joseph E
Wiley David
WorldCom, Inc.
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