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BACKGROUND OF THE INVENTION
The present invention relates to distributed processing and more
particularly to interchange of data in communication system having one or
more host processors connected for cooperative interaction with a
plurality of intelligent terminals or work stations.
Cooperative processing is well known in the art, illustrative of which are
systems such as those depicted in FIG. 1 hereof, wherein a host processor
is operative in a purely reactive mode to requests for objects (data and
processing routines) requested by the connected terminal/work stations.
While such systems provide substantial economies of equipment by providing
for the sharing of selected computational features at a consolidated
level, (i.e., at a host processor) they nevertheless require two flows of
information for each item communicated from the host to a connected
terminal/work station:
(1) The initiation of a request at the work station communicated over a
data link to the host; and
(2) Data generated or otherwise produced at the host and communicated over
a data link back to the requesting terminal/work station.
When the host processor is busy, requests for information may await their
turn in a queue, thereby resulting in significant delays. Moreover, even
if there is no queue, and the request for data is responded to immediately
upon receipt, there nevertheless is a loss of time occasioned by the need
for the requesting terminal to transmit a request to the host together
with loss of time involved in production of requested data and their
communication by the host back to the terminal over the connecting link.
Moreover, it is desirable further to improve the efficiency of time and
equipment utilization in systems of the type described herein in order to
provide a storage hierarchy within terminal work stations whereby the
terminal work stations can anticipate the future need at the work station
of certain types of data and or processing information (hereinafter
referred to as "objects") and to have them stored at the work station so
that such objects are available for utilization (display/processing)
immediately upon request by the user without having to obtain them from
the host, thereby substantially improving time efficiency and equipment
utilization.
OBJECTS AND FEATURES
It is one general object of this invention to improve distributed data
processing systems.
It is another object of this invention to improve time efficiency in
utilization of intelligent work stations.
It is another object of this invention to improve efficiency of equipment
utilization in distributed processing systems.
It is yet another object of this invention to facilitate utilization of the
equipment and attendant productivity of equipment user personnel.
In accordance with one feature of the invention items requested by a given
work station from the host are automatically retained in the storage of
such work station in accordance with a predetermined order of priority.
In accordance with another feature of the invention, objects are retained
in memory at the work stations until either: 1. a pre-determined period of
time has passed without their being used; or 2. until the available memory
at the terminal/work station is full and a higher priority item seeks
entry thereto, thereby reducing response time and improving efficiency.
These and other objects and features of the invention will be apparent from
the following detailed description, by way of preferred embodiment, with
reference to the drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a flow chart illustrating operative principles embodied in the
prior art;
FIG. 2 is a flow chart illustating the preferred embodiment of the
invention;
FIG. 3 is a diagram identifying two types of information for which the
principles of the invention are particularly useful; and
FIG. 4 illustrates the preferred hierarchy of retention priorities at the
work stations.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIG. 1, a typical distributive processing system according
to the prior art is illustrated. Steps progress operately in descending
order from top to bottom and represent, by vertical column, the host
processor, terminal/work station and user respectively. As will be
observed from the top of the host column, action begins with starting of
the host system and the terminal/work station(s) respectively. These
actions are represented by start symbols 10 and 20. In this connection, it
should be observed that reference to terminal and/or work station when
used in the singular is intended to include the plural and vice versa
unless the context requires otherwise.
Once the system is activated, objects are received at the host as
represented by the descriptor "object item arrives", symbol 12. This is
accomplished in accordance with generally known techniques. After arrival,
the object item is stored at the host for later retrieval when a request
is subsequently received from the user for such item.
When a user elects to view the object, e.g., object 1 as noted by symbol
40, he or she makes an appropriate entry, normally by manipulation of a
keyboard or the like; and in response thereto, the work station develops
and sends to the host a request for the object as denoted by symbol 21.
Upon receiving such an input, the work station circuits transmit a request
for the object over communication link 22 to the host processor with a
request that the identified object be sent to the work station. This then
is accomplished as represented by communication link 23, and the work
station equipment accepts the requested object and then displays it to the
user as noted by symbol 24. The item may be temporarily retained at the
work station until the memory capacity is needed for the next item.
Ordinarily, however, the item is not retained in storage at the work
station and consequently must be recalled again from the host if it is to
be viewed subsequently. This is represented by the sequence beginning with
selection by the user to view the object as denoted by symbol 41. Circuits
in the work station are then activated as denoted by symbol 25 and act in
the manner similar to that denoted by symbol 21 to send a request to the
host over transmission path 26 to circuits in the host which responds as
noted by symbol 15 to send the requested object to the work station over
communication link 27. The object is then displayed to the user as denoted
by symbol 28.
Should the user desire to view a different object (e.g., object 2) a
procedure similar to the foregoing is employed, with the user electing to
view the object as denoted by symbol 42 to send a request to the host and
receive the object as denoted by symbols 29, 30, 31 and 16. Other similar
sequences of operation are represented by symbol 17, 18 and 19 at the host
station and by symbols 32, 33 and 34 at the work station. Completion of
the foregoing sequences or deactivation are denoted by symbols 20 and 35.
From the foregoing, it will be observed that in accordance with the prior
art, after display of the object or utilization thereof by the work
station, the object is not stored there but is retained at the host,
thereby requiring subsequent individual retrievals of the object from the
host for use or display.
Now turning to FIG. 2, it will be observed that the present invention is
illustrated therein. As with the prior art, the inventive system includes
a host and one or more work stations. These are presented in a form
similar to that of FIG. 1, and are activated by start-up which is
indicated by symbols 50 and 70 respectively. As with the case of the prior
art, objects are received and are represented by "object item arrives",
symbol 51. Next, the memory 52 stores the object item in accordance with
principles known in the prior art. The object is thus available for
transmission to a work station upon request. Thus the host is conditioned
to respond to a specific request from a work station and to send the
object to the work station as represented by symbol 56.
Communicaticn between the host circuits 56 and the corresponding work
station circuits 71 is effected over communication links 53 and 54.
Deactivation of the host system is of course, represented by "end" symbol
58.
As mentioned above, circuits at the work stations are equipped with
sufficient storage capacity to store and retain objects ordinarily desired
and/or used by the work station operators. Accordingly, after an object
item has been received by circuits 71 or 75, it is stored in storage 63
(which is symbolic of memory or DASD at each work station) where it
remains until, because of inactivity or need for replacement by an object
of higher priority, it is erased therefrom. Paths inter-connecting
circuits 71 and 75 with memory 63 are identified by communication paths 61
and 65.
As shown in FIG. 2, displays of requested objects, e.g., mail, to the user
are identified by symbols 73, 74 and 76. Of course, it will be evident to
those skilled in the art that these are representative of a number of
different showings of the same or different objects.
Completion of a sequence of actions or eventual deactivation of the system
is denoted by symbols 58 and 77 in the conventional manner.
Again as evident from inspection of FIG. 2, a work station user may select
to view an object that is either currently resident within local storage
63 or which must be summoned from the host. However, it is not necessary
for the user to know where the data is stored. Symbol 80 represents
selection by the work station user to view one or more objects resident in
host storage 52, symbol 81 identifies selection by the user of viewing the
same object(s) which by then has been stored in work station storage 63,
and symbol 82 identifies selection by the user of a different object
(e.g., object 2) which must be summoned from the host processor. Thus, in
accordance with a feature of the invention, two modes of operation are
provided whereby the user can select items that are currently in the host
only or in the host and work station storage.
Reference is herein made to co-pending U.S. patent application Ser. No.
07/312,223 filed on even date herewith by the inventors hereof and issued
as U.S. Pat. No. 5,029,104 on Jul. 2, 1991 for "Prestaging Objects in a
Distributed Environment." In that application reference is made to
different types of data objects that are useful at local work stations
such as those herein described.
In operation, a user selects to view an object, such as object 1. This is
represented by symbol 80. In response to thereto, circuits 71 interrogate
local storage 63 via conducting path 61 to ascertain whether or not the
requested item is currently in local storage. If not, it then communicates
via conductor 53 to host circuits 56 which respond by communicating the
requested information via conducting path 54, to circuits 71 whence it is
then shown to the user as indicated by symbol 73. At the same time, the
item of information is communicated via path 61 to storage 63, where it is
stored in accordance with the hereinafter described hierarchy of
priorities.
If when the user selected to view object 1 as indicated by symbol 80,
circuits 71 found the requested information currently in storage 63, it
would have resulted in the communication of such information via
communication link 62, to circuits exemplified by symbol 73 for display to
the user.
Since in any event, the item is now stored within storage 63, when a user
subsequently selects to view the same object as represented by symbol 81,
the requested object is communicated from storage 63 to circuits 74 via
link 79. The object is then displayed to the user.
When the user selects to view another object, e.g., object 2, as
represented by symbol 82, circuits as represented by symbol 75, are
activated to send a request via communication link 59, to circuits 57
where they are effective to result in the transmission of the requested
data via link 60, to circuits 75. The object is then shown to the user as
represented by symbol 76. As will be evident from a further inspection of
the drawing, prior to sending a request to the host via communication
links 59, circuits represented by symbol 75 interrogate storage 63, via
link 65, to ensure that the requested object is not already in storage
locally. If such should be the case, the requested object data is
transmitted to circuit 76, by a link represented by symbol 64. If not then
the object is obtained from the host via link 60, and the object will be
stored in storage 63 via link 65.
Now turning to FIG. 3, three categories of information are shown for which
the principles of the invention are particularly efficacious These are
"directory", "electronic mail" and "library". As will be evident to those
skilled in the art, the directory 90 is for providing the user with a list
of items such as names, addresses and telephone numbers which are of
sufficient interest to the user to justify their inclusion in such a list.
Of course, a directory may include other items of information such as
routing information, building locations and the like which are necessary
or desirable in identifying and/or achieving effective communication with
a designee.
Electronic mail 93 is provided for storage of selected items of mail which
are newly arrived, designated by the user for retention, or are being
maintained at the work station for a predetermined or indeterminate
interval of time. For additional information regarding electronic mail,
reference is hereby made to the above identified co-pending application.
Library 91, symbolizes a storehouse of information such as articles of
interest, references, bibliographies and the like; although it may, at the
discretion of the user, include otehr kinds of information which the user
designates for inclusion. Such items often include substantial quantities
of data, and consequently their presence locally avoids the necessity of
repetitively communicating substantial quantities of such data between the
host and local work stations.
In order to maximize the usefulness of available local storage (e.g.,
storage 63), a hierarchy of data retention priorities may be established.
Such priority may be tailored to meet the requirements of the local user,
but optionally provides for at least interim storage of the most recently
received item which, if necessary because of overcrowding of available
storage space, will displace an item or items of lowest priority. The
order of hierarchies then is bascially time and use dependent in that
recent use establishes or re-establishes a higher position within the
priority queue, whereas lack of use gradually lowers the level of priority
until an item, because of non-use, is displaced by a newly arrived item
FIG. 4 illustrates the preferred hierarchy of retention priorities,
preferably employed in practicing the invention. There, it will be
observed, the most recently used object is accorded the highest priority
for retention, whereas the most remotely used object is accorded the
lowest retention priority. This is illustrated by the dashed line 103
according to which the next most remotely used object 104, if used after
the most recently used object 101, then replaces it as the most recently
used object 101. The replaced 101 becomes 105 as it is decreased in
position to the second highest location as shown in the figure. When the
next object is received by the work station, all of the items in the queue
descend one position, resulting in the elimination of the lowest item 102
which then is lost from local memory. However, if before that occurs, item
102 were to be used, it would then be raised to the highest priority.
In summary, through the cooperative interaction of memories in both the
host processor and the work stations, the most used data is stored at the
work station locations and is immediately available thereat, thereby
reducing the number of interactive communications required to support user
needs and resulting in a corresponding improvement in efficiency and time
reduction.
It will now be evident that what has been described herein a distributive
processing system having substantially improved features. Although the
inventive concepts hereof have been illustrated by way of a preferred
embodiment, it will be evident to those skilled in the art that other
adaptations and modifications may be employed without departing from the
spirit and scope of the invention.
The terms and expressions herein employed are used as terms of description
and not of limitation, and there is no intent in the use thereof to
exclude equivalents, but on the contrary it is intended to include any and
all equivalents, adaptations and modifications that can be employed
without departing from the spirit and scope of the invention as described
in the specification and claims herein.
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