Electrical computers and digital processing systems: multicomput – Computer network managing – Network resource allocating
Reexamination Certificate
2000-01-07
2002-03-26
Winder, Patrice (Department: 2155)
Electrical computers and digital processing systems: multicomput
Computer network managing
Network resource allocating
C709S201000, C709S227000
Reexamination Certificate
active
06363426
ABSTRACT:
FIELD OF THE INVENTION
The present invention concerns the field of allocating or assigning modems from one or more modem banks to a plurality of software applications requiring a modem. More specifically, the invention concerns a system and method that segregates the functional components of modems and delays the allocation of a data pump to a software application until a point when the software application requires a physical modem.
BACKGROUND OF THE INVENTION
Computer software applications use modems by issuing a series of commands to the modem often called the “AT Command set” (such as “AT&V” or “ATDT 555-1234”). When a software (client) application opens a communication port to a modem, it expects an immediate, near-zero-latency connection to the modem. When a modem processes a command issued by the software application, it provides a response (such as “OK” or “ERROR”) to the application. Upon the processing of a command, a modem may also modify its internal state or it may initiate an action, such as dialing or hanging up a modem call.
FIG. 1
shows one common, prior art configuration by which a modem is interfaced with a software application. In this configuration, the software application
10
allocates a modem by opening a communications port
14
(COM port) provided by the computer's operating system
12
. The COM port
14
is directly attached to a modem
18
via a direct connection
16
, such as a cable or bus interface. The software application
10
then interacts with the modem
18
beginning with the first modem command that is issued by the software application
10
. In this case, the type of modem needed is known and application-to-modem timing issues are non-existent.
Another well-known, prior art, configuration for interfacing a modem to a software application utilizes a “static modem allocator”. Such a configuration, as shown in
FIG. 2
, is prevalent with modern client-server systems, where one or more client computers
20
communicate with a network server
30
over a computer network
28
, such as a local area network (LAN). In this configuration, the COM port
14
of the configuration of
FIG. 1
is replaced by a “virtual COM port”
26
. Thus, instead of opening a physical COM port and allocating a physical modem, the software application
22
of this configuration opens a virtual COM port
26
provided by the operating system
24
.
In this configuration, the direct modem connection is replaced by several components that allow the application to use any one of a number of modems that are attached to the network server
30
. These components include the LAN
28
, which provides a communications link between the client computer
20
and the network server
30
. The server
30
has a simple modem allocator
32
that selects an available modem from a set of modems
34
a-n
before a first modem command is issued by the software application.
As in the direct attachment configuration, once an available modem is allocated to the software application
22
by the modem allocator
32
, the software application
22
interacts with a specific physical modem
34
beginning with the first modem command. This is the method widely used by today's modem-sharing server systems and related software. Again in this configuration, a physical modem is allocated and timing issues are minimal.
However, there are situations where the selection of a modem will depend, in large part, on information contained in commands issued by a software application subsequent to the first command. This means that some portion of the interaction of the application with a modem must occur before the specific modem to be allocated can be chosen and selected.
For example, a modem command issued by a software application may indicate that the application requires a specific type of modem (e.g. a fax modem, analog modem or an ISDN modem). If not all of the available modems are of the required type, then a modem cannot be allocated until after the specific type is identified.
In addition, with the increased use of large scale computer networks, such as the Internet, there are situations where available modems may be geographically dispersed in order to take advantage of low cost network-based data transmission over great distances and only utilize more costly public switched telephone network (PSTN) lines where they are more cost effective to use and/or necessary (i.e. for local telephone connections between the computer running the software application and the large scale computer network and/or the large scale computer network and an ultimate destination). In such situations, a final modem command may be a dial command, and it is only at that time that a modem can be selected utilizing a least-cost routing or other similar algorithm.
In addition, by waiting until the dial command is issued, the load on the large scale computer network will be minimized until a modem is actually required. In other words, the software application does not need to access a physical modem until it performs an operation that requires interaction with the PSTN. Before that point, it only serves to increase system load to allocate a modem when, in fact, the software application does not require it.
However, delaying the point at which an actual modem is allocated to a software application creates several additional problems that must be addressed. First, modem commands modify the internal state of a modem incrementally. In other words, at any point in time, a modem's current state is the result of a series of commands that it has received in a specific order. Software applications also expect to receive immediate and certain responses from a modem upon the issuance of certain commands. Therefore, if a modem has not been assigned to a software application to receive and respond to commands issued by the software application, the application will, in most instances, report an error condition and may not initialize properly.
Also, if a modem is not allocated to an application until a later point in time, then, even if the software application does not detect an error, the allocated modem may not be in the required state to accept additional commands from a software application subsequent to the allocation of the modem to the application.
Accordingly, what is needed is a system and method of allocating modems to software applications that is compatible with the delayed allocation of modems. Such a system and method must be able to accurately determine and maintain a proper desired state of a modem at the time of modem allocation and provide the required responses to various software applications with the proper timing sequence upon the issuance of response-requiring modem commands.
SUMMARY OF THE INVENTION
The present invention provides a system and method of delayed modem assignment which overcome the problems associated with delaying the allocation or assignment of a physical modem to a specific software application until one is ultimately required, i.e. upon the issuance of a dial-out command.
The present invention introduces a new modem architecture wherein the two major components included in all current modems, i.e. the modem controller and the data pump, are separated. The system of the present invention provides a modem controller closely coupled to the software application to control and account for the effects of modem controller timing issues between the modem controller and the software application. Preferably, the modem controller is implemented in software running on the same computer running the software application. The system distributes a plurality of data pumps, which can be assigned or allocated to a modem controller at an optimum point in time so as to promote operational efficiency.
In order to properly assign or allocate a data pump to a modem controller, the system of the present invention also includes a delayed data pump allocator, which receives a data pump allocation request issued by a modem controller and which selects a best fit data pump to allocate to the requesting modem control
Krueger Michael M.
Yon David A.
Dialout.Net, Inc.
Winder Patrice
LandOfFree
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