Method and interface device for sharing physical resources

Details Method and interface device for sharing physical resources Method and interface device for sharing physical resources

1995-06-14

2001-10-23

Banankhah, Majid A. (Department: 2151)

Electrical computers and digital processing systems: multicomput

Computer-to-computer data routing

Least weight routing

C709S241000, C709S241000, C709S241000

Reexamination Certificate

active

06308196

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally concerned with client-server type data processing architectures. In architectures of this kind a first processor called the server is connected to physical resources, for example an electrical control unit or a measurement unit, which are made available to one or more second processors, called clients, which are not connected directly to those resources.
The invention is more precisely concerned with sharing physical resources associated with a first processor between the first processor and one or more second processors. To simplify the remainder of the description, it is assumed that a single second processor shares physical resources with a first processor with which those resources are associated.
2. Description of the Prior Art
FIG. 1
shows the first and second processors
1
and
2
in a highly schematic fashion although in one implementation both may be computers.
The first processor
1
is associated with physical resources
1
a
which are not directly accessible to the second processor
2
. To obtain access to the physical resources
1
a
associated with the first processor
1
, the second processor
2
sends to the first processor
1
a message REQ(X
1
. . . X
M
) requesting access to said resources. The access request message REQ(X
1
. . . X
M
) includes M parameters X
1
. . . X
M
defining the nature of the access to the required resources. After receiving this message and accessing the physical resources
1
a
via interface means, the first processor
1
send to the second processor
2
a response message REP(Y
1
. . . Y
N
). This response message includes information relating to the result of the request to access the resources
1
a
sent by the second processor
2
via the first processor
1
.
Consider, by way of example, the situation in which the physical resources
1
a
are in the form of an electrical control unit. It may then be assumed that the message REQ(X
1
. . . X
M
) is a remote control message to activate an electrical device in accordance with predetermined activation information. The message REP(Y
1
. . . Y
N
) then contains one or more numerical parameters defining the result of the remote control action(s) and provided by the electrical control unit
1
a.
Obviously, depending on the nature of the access to the resources
1
a
, the respective numbers M and N of parameters (X
1
. . . X
M
) and (Y
1
. . . Y
N
) sent in the request message REQ(X
1
. . . X
M
) and in the response message REP(Y
1
. . . Y
N
) can have any values.
As shown in
FIG. 2
, the first processor
1
is typically a processor or a microprocessor
10
, also referred to hereinafter as the “processor circuit”,and a computer program
11
s
. The processor circuit and the program cooperate to control and monitor the physical resources in the form of a control unit
1
a
and to exchange data with the latter. The program
11
s
controlling the operation of the microprocessor
10
can be divided into separate subroutines or basic tasks activating the microprocessor
10
to execute respective specific functions concerning control and monitoring of the physical resources
1
a.
In the prior art, when physical resources
1
a
are to be made available to a client processor
2
, it is necessary to modify the source program
11
s
interfacing the first processor
1
to the physical resources
1
a
so that the processor
1
can accept messages REQ(X
1
. . . X
M
) requesting access to the resources from the client processor
2
. The program
11
s
, which is a source program in a high-level language, is initially modified to define all types of resource access request messages that the first processor
1
can receive to request access to the physical resources
1
a
. When all access request message types have been defined, it is then necessary to introduce (as shown in
FIG. 2
in the dashed outline box
11
′) the computer language equivalents of all the “IF-THEN” alternatives for access to the physical resources conditioned by the values taken by the parameters (X
1
. . . X
M
) contained in the messages REQ(X
1
. . . X
M
). These alternatives also define program jumps to predefined program addresses, as shown by the arrows on the lefthand side in FIG.
2
.
This prior art solution has two major drawbacks.
Firstly it requires systematic reprogramming of the program in the server processor
1
when new types of access for new uses of the physical resources are defined. Secondly, it greatly increases the size of the program
11
s
when compiled, by addition of the additional program portion
11
′.
The invention is directed to remedying the above drawbacks by providing a process which, for the purpose of sharing resources with a client processor, requires no modification of the program which, in cooperation with the microprocessor, manages the physical resources in the server processor. The invention also provides an interface device for implementing this method.
SUMMARY OF THE INVENTION
In one aspect, the present invention consists in a method of sharing physical resources associated with a first processor between said first processor and a second processor, said method including sending of a message requesting access to said resources from said second processor to said first processor, and said first processor including a processor circuit associated with a program memory and a data memory,
which method comprises the steps of:
associating with the value assumed by a first parameter contained in a first field of said access request message a respective associated address designating a given location in said program memory and identifying the start of one of a plurality of tasks which access said physical resources,
writing respective values assumed by or associated with second parameters contained in a second field of said access request message with predetermined first locations in said data memory associated with said first processor, said predetermined first locations being such that said task accesses each of said first predetermined locations when it is executed, and
loading said associated address into an execution register of said processor circuit included in said first processor in order to initiate said task,
said steps being implemented by an interface device and a program required for operation of said interface device being dissociated from each task of said plurality of tasks.
For an embodiment of the invention in which execution results are supplied by the task, there is provided the further step of:
reading by said interface device of parameters resulting from execution of said task by said processor circuit and memorized at predetermined second locations in said data memory associated with said first processor to form a response message sent to said second processor,
said reading step being implemented by said interface device in response to end of execution of said task.
In a multitasking environment the first and second processors are both associated with the same processor circuit.
The interface device is typically the result of execution of said program by said processor circuit associated with said first processor.
In another aspect, the present invention consists in an interface device for implementing the above method. The device receives said access request message from said second processor, cooperates with said first processor and comprises:
correspondence table means for associating with each value that said first parameter can assume a respective one of a plurality of addresses designating respective locations in said program memory, and
means for successively addressing each of said predetermined first locations in said data memory and writing in corresponding relation thereto each of said respective second values assumed by said second parameters contained in said second field of said access request message.
Other features and advantages of the present invention will emerge more clearly from a reading of the following description given with reference to t

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