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| United States Patent | 4941084 |
| Link to this page | http://www.wikipatents.com/4941084.html |
| Inventor(s) | Terada; Matsuaki (Machida, JP);
Wataya; Hiroshi (Hitachi, JP);
Takagi; Satoru (Kawasaki, JP);
Sueki; Masao (Hitachi, JP) |
| Abstract | A resource management system and method in a distributed processing system
in which a plurality of computers are interconnected through a
transmission line. A computer makes, upon accessing to a resource of
another computer, inquiries about "Whether the intended resource exists"
and "Ordering that if the intended resource exists, the interrogated
computer should return a response indicative of attribute information of
that resource" by using a so-called broadcasting function to
simultaneously apprize all the computers constituting the distributed
processing system of the same message. |
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Title Information  |
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Drawing from US Patent 4941084 |
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System for locating resources resided in a distributing processing
system by sequentially transmitting resource inquiries through a looped
transmission line |
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| Publication Date |
July 10, 1990 |
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| Parent Case |
This application is a continuation of application Ser. No. 766,196, filed
Aug. 16, 1985. |
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| Priority Data |
Sep 14, 1984[JP]59-191555 |
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Title Information |
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Claims |
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We claim:
1. A resource management system in a distributed processing system, said
management system comprising:
a plurality of arithmetic processing means;
at least one resource belonging to each arithmetic processing means;
a unidirectional looped transmission line interconnecting said plurality of
arithmetic processing means for exchanging information therebetween; and
storage means provided in each of said plurality of arithmetic processing
means, for storing a resource management table which registers an
identification code and attribute information of a resource belonging to
said arithmetic processing means, said attribute information including
information for specifying a location of said resource; and
a first one of said plurality of arithmetic processing means including
means for effecting an inquiry through said transmission line, to all
other arithmetic processing means to determine whether any one of said
other arithmetic processing means contains a resource represented by an
identification code desired by said first arithmetic processing means;
wherein, said inquiry being performed by sending an inquiry request from
said first one of said arithmetic processing means to a second arithmetic
proceeding means of said other arithmetic processing means, determining by
said second arithmetic processing means whether a resource requested by
said inquiry request is contained therein, and if said requested resource
is not contained in said second arithmetic processing means sequentially
passing said inquiry request to each of said other arithmetic processing
means until said requested resource is found; and
wherein each of said other arithmetic processing means includes means for
making reference to the resource management table contained therein to
examine whether it contains the desired resource and means for effecting a
response processing to transmit, through said transmission line, an
identification code and attribute information of said desired resource to
said first arithmetic processing means when said reference means detects
said desired resource so that said first arithmetic processing means can
access said desired resource by using said attribute information.
2. A resource management system according to claim 1, wherein said first
arithmetic processing means further comprises a cache table in which said
identification information and attribute information provided by one of
said other arithmetic processing means are stored, said first arithmetic
processing means including means for searching said cache table prior to
effecting said inquiry processing and for omitting said inquiry processing
when it is determined from a search of said cache table that said
attribute information of said desired resource has already been stored in
said cache table.
3. A resource management system according to claim 2, wherein the contents
of said cache table are purged when said one of said other arithmetic
processing means is withdrawn from said distributed processing system.
4. A resource management method in a network system having a plurality of
stations interconnected through a transmission unidirectional looped line,
each station being connected to a data processing means for managing at
least one resource, comprising the steps of:
broadcasting an inquiring message inquiring as to a location of a requested
resource from a first one of said data processing means to said
transmission line through a first station connected with said first data
processing means when a request is made by an application program of said
first data processing means to access a resource not under the management
of said first data processing means;
receiving said inquiring message within a data processing means of other
data processing means connected to said transmission line;
examining a resource management table included in said data processing
means to determine whether the requested resource is under the management
thereof;
suquentially passing said inquiry message to other data processing means
connected to said transmission line until said requested resource is
found;
sending a response message containing attribute information of said
requested resource back to said first data processing means, from a second
data processing means of said other data processing means, when said
requested resource is determine to be under management of said second data
processing means; and
sending an accessing message for accessing said requested resource from
said first data processing means to said second data processing means
using said attribute information contained in said response message when a
response message is sent from said second data processing means to said
first data processing means.
5. A resource management method according to claim 4, wherein said
attribute information contained in said response message includes physical
identification information of said requested resource. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
This invention relates to a distributed processing system in which a
plurality of computers are interconnected through a communication system
and more particularly to a resource management system suitable for
allowing the computers to share resources.
In a conventional distributed processing system, each computer has a
configuration table indicative of what resources the other computers have.
When a computer does not have a resource required for its own sake, this
computer examines the configuration table and requests another computer
having the requisite resource to allow the utilization of this resource.
However, it is usual in the distributed processing system to add or
withdraw a computer or computers as necessary, and the configuration table
owned by each computer must be changed each time the computer installation
is changed.
SUMMARY OF THE INVENTION
An object of this invention is to provide a resource management system in a
distributed processing system which is able to keep a configuration table
of each computer unchanged even when addition or withdrawal of a computer
or computers occurs.
To accomplish the above object, according to this invention, a computer
makes, upon accessing to a resource of another computer, inquiries of the
other computers constituting the distributed processing system about
"Whether the intended resource exists" and "Ordering that if the intended
resource exists, the interrogated computer should return a response
indicative of attribute information of that resource". Advantageously,
this construction allows each computer to manage only resources of its own
and to retire from storing locations of resources existent in the other
computers, and therefore there is no need of changing network
configuration tables of the other computers even when the system
construction is changed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram showing the construction of an embodiment of an
in-house or local area distributed processing system to which the
invention is applied;
FIG. 2 is a block diagram showing the construction of a resource management
system according to an embodiment of the invention;
FIG. 3 shows a format of a resource management table according to the
embodiment;
FIG. 4 shows a format of an inquiry frame according to the embodiment;
FIG. 5 shows a format of a response frame according to the embodiment;
FIG. 6 is a flow chart showing an inquiry operation according to the
embodiment;
FIG. 7 is a flow chart showing a response operation according to the
embodiment; and
FIGS. 8a-8b are block diagrams of other embodiments of the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention will now be described by way of example with reference to the
accompanying drawings.
FIG. 1 shows schematically an in-house distributed processing system to
which the invention is applied. The system comprises computers 1-1, 1-2,
1-3 and 1-4, stations 2-1, 2-2, 2-3 and 2-4 respectively associated with
the computers, and a transmission line 3 interconnecting the stations.
A message sent from a station is sequentially relayed by another station to
propagate along the transmission line. The message transmission along the
transmission line 3 is always unidirectional. When the message arrives at
a destination station, this station fetches the message. In this manner,
communications are effected between the stations.
Taking a computer 1-i and another computer 1-j included in the in-house
distributed system into account, their constructions are diagrammatically
shown in FIG. 2.
As shown, the computer 1-i includes a resource management program 4-i, a
resource management table 5-i, and an application program 6-i used for
requesting the utilization of a resource 7-i. The resource 7-i is
constituted with at least one of units such as data, an input/output unit
and a program. Likewise, the computer 1-j includes a resource management
program 4-j, a resource management table 5-j, an application program 6-j
and a resource 7-j.
The resource management table 5-i or 5-j has a format as shown in FIG. 3.
The format consists of entries 8-1 to 8-nholding names of resources and
entries 9-l to 9-nholding pieces of attribute information of the
resources.
The names of resources are uniquely or definitely assigned to the
respective resources included in the in-house distributed processing
system, and the application program 6-iaccesses the resources by their
names.
The attribute information of a resource is indicative of kind and location
of the resource. Taking a printer as a resource, for instance, the printer
is categorized by the kind of resource into one dedicated to Chinese
character use or one dedicated to alphabetical character use. The location
of a resource indicates which computer the resource belongs to or what
physical number the resource has.
Since, in this embodiment, the computer is associated with the station in
one-to-one correspondence relationship, designation of the location of a
resource directly results in designation of the corresponding station. But
the invention is not limited to this association and a single computer may
be connected to a plurality of stations. In this case, it will be obvious
to those skilled in the art that the attribute information further
includes a data indicative of which station belongs to the single
computer. Conversely, a plurality of computers may be associated with a
single station in a similar manner.
In the respective resource management tables 5-i and 5-j, only resources
present in the respective computers 1-i and 1-j are enrolled.
FIG. 4 illustrates a format of an inquiry frame 10 sent from the computer
1-i to all the computers inclusive of the computer 1-j shown in FIG. 2
through the transmission line 3.
The format of the frame 10 consists of a special pattern (SYNC) 10-1 for
synchronization of the transmission line, additional special patterns (F)
10-2 and 10-9, respectively, indicative of the beginning and end of the
frame, an address (DA) 10-3 of a destination station 2-j for which the
inquiry is destined, a source address (SA) 10-4 of a station 2-i, a
control byte (C) 10-5 for various types of controlling, an inquiry command
(COM) 10-6, a name of a resource (NAME) 10-7 to be inquired, and a frame
check sequence (FCS) 10-8 for detection of errors.
The DA 10-3 of the inquiry frame 10 is set to a specified bit pattern
(typically all "1") so as to make the broadcasting valid wherein the
inquiry frame 10 is received by all of the remaining stations. This bit
patterning is of course for illustrative purposes only and the bit
patterning for the broadcasting is not limited thereto.
If the computer 1-j has a resource corresponding to the NAME 10-7
designated by the inquiry frame 10, the computer 1-j sends to the
transmission line 3 a response frame 11 having a format as shown in FIG.
5.
Thus, the interrogated computer 1-j returns the response frame 11 of the
FIG. 5 format having a special pattern (SYNC) 11-1, additional special
patterns (F) 11-2 and 11-9, a source address (SA) 11-4, a control byte (C)
11-5 and a frame check sequence (FCS) 11-8 which are the same as those of
the inquiry frame format, and the other bytes 11-3, 11-6 and 11-7 which
are characteristic of the response frame.
More specifically, the destination address (DA) 11-3 has, unlike the
inquiry frame 10, an address of the source station 2-i which transmits the
inquiry frame 10. The response (RES) 11-6 indicates that this frame 11 is
a response frame, and the attribute information (ATR) 11-7 is for a
resource subject to the inquiry.
The inquiry operation of the resource management program 4-iis exemplified
in a flow chart of FIG. 6, and the inquiry reception operation of the
resource management program 4-j is exemplified in a flow chart of FIG. 7.
The inquiry and inquiry reception operations of these resource management
programs will now be described in greater detail with reference to FIGS. 6
and 7, respectively.
Inquiry Operation (See FIG. 6)
The resource management program 4-i of the computer 1-i receives a resource
access request from the application program 6-i and initiates an inquiry
operation.
The application program 6-i then transfers a name (NAME) of a resource to
be accessed to the resource management program 4-i. The resource
management program 4-i searches the resource management table 5-i for the
NAME to examine the presence or absence of the NAME (step 61). If the NAME
exists, the corresponding attribute information is read out and returned
to the application program 6-i.
If the NAME is not in the resource management table 5-i, the inquiry frame
10 is prepared and sent through broadcasting to all the computers
inclusive of the computer 1-j, bringing about a condition ready for
reception of the response frame (step 62).
If the resource designated by the NAME exists in the computer 1-j, the
response frame 11 is returned from the computer 1-j. If there is no
response frame returning from any of the remaining computers inclusive of
the computer 1-j, the inquiry frame 10 is retransmitted. If no response
frame occurs even when the inquiry frame 10 is retransmitted m times, the
application program 6-i is informed of the fact that the accessing to the
resource is invalid (step 63).
When the response frame 11 is returned, the attribute information (ATR)
11-7 is taken out and the application program 6-i is apprised of the ATR
(step 64).
The application program 6-i actually accesses the resource by using the
attribute information thus obtained. More particularly, the application
program 6-i designates a destination station and delivers the attribute
information of the resource and the access request to the station 2-i.
This station 2-i sends a frame inclusive of the attribute information and
access request to the designated station.
Inquiry Reception Operation (See FIG. 7)
When the resource management program 4-j included in the computer 1-j
receives the inquiry frame 10 from the computer 1-i (step 71), an inquiry
reception operation is initiated.
The resource management program 4-j takes the NAME 10-7 out of the received
inquiry frame 10 and by referring to the resource management table 5-j,
examines whether an entry having the NAME exists (step 72). If it exists,
the attribute information is taken out (step 73), and the response frame
11 is prepared and transmitted to the source computer 1-i which has
originated the inquiry frame 10 (step 74).
If the NAME is not in the resource management table 5-j, the response frame
11 is not prepared and returned.
The present invention is not limited to the foregoing embodiment but it may
be modified as follows and shown in FIGS. 8a and 8b:
(1) In the foregoing embodiment, when the resource management table 5-idoes
not have the requested NAME, the inquiry frame is immediately issued. In
order to decrease the overhead of the inquiry, however, a cache table 75
may preferably be provided.
With the cache table 75, a pair of NAME and attribute information obtained
as a result of one inquiry is enrolled in the cache table 75 having a
similar format to that of FIG. 3.
Upon initiation of an inquiry operation, the cache table is first referred
to prior to the transmission of the inquiry frame 10 through broadcasting
so as to examine whether the attribute information has already been
acquired. If acquired, the attribute information is returned to the
application program 6-iand the inquiry through broadcasting is omitted.
When addition or withdrawal of a computer or computers occurs, the
registered contents of the cache table 75 are purged.
Advantageously, this ensures, that the system construction remains
unchanged, that once the broadcasting communication is initially
performed, the same resource can be utilized repetitiously.
(2) The communication system is not limited to a data system but instead,
it may be of a packet exchange network or a satellite communication.
(3) The distributed processing system is not limited to the in-house system
but instead, it may be of a broad area distributed processing system.
(4) This invention can be implemented efficiently by making inquiries
through the broadcasting. But the respective computers may be interrogated
separately without resort to the broadcasting.
As described above, since according to the invention the respective
computers constituting the distributed processing system are simply
required to have the local configuration table regarding the resource of
the respective computers and its own configuration table need not be
changed even when the number of the computers and the number of the
resources involved in the system are changed, the distributed processing
system can be changed or extended with ease.
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Description |
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