Electrical computers and digital processing systems: multicomput – Distributed data processing – Client/server
Reexamination Certificate
1998-06-01
2001-07-17
Luu, Le Hien (Department: 2152)
Electrical computers and digital processing systems: multicomput
Distributed data processing
Client/server
C707S793000
Reexamination Certificate
active
06263360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to client/server object-oriented computing systems. More particularly, the present invention relates to maintaining updated information on low-bandwidth client/server object-oriented computing systems.
2. Description of the Related Art
The use of object-oriented computing systems, e.g., distributed object-oriented computing systems, is increasing as the use of networked computing systems increases. Networked computing systems such as object-oriented computing systems generally allow resources to be shared among different computers associated with the network. Object-oriented computing systems often use client/server models. That is, many object-oriented computing systems are client/server computing systems. A client, which is in communication with a server, is typically arranged to remotely accesses resources associated with a server.
With reference to
FIG. 1
, the interactions between a server and clients which are linked via a network will be described. In general, within a client/server object-oriented computing system
100
, a server
102
is in communication with clients
106
. Although communications between server
102
and clients
106
may generally be initiated using an object request broker (ORB) as will be appreciated by those skilled in the art, communications often take place directly between server
102
and clients
106
. By way of example, when client
106
a
requires information that is available on server
102
, once a communications link
110
a
is established between client
106
a
and server
102
, client
106
a
may request information directly from server
102
. Similarly, when server
102
responds to a request from client
106
a
, server
102
may respond directly to client
106
a
. As such, information on server
102
may essentially always be available to clients via communications links
110
.
In client/server object-oriented computing system
100
, communications links
110
are typically high bandwidth links, and clients
106
are typically non-volatile clients. That is, once established, communications links
110
remain established until they are deactivated by server
102
or clients
106
. Hence, clients
106
remain in communication with server
102
, e.g., “subscribed” to server
102
, until such time as clients
106
“desubscribe” themselves from server
102
. Since a client, as for example client
106
a
, generally remains linked to server
102
until client
106
a
terminates link
110
a
, client
106
a
may request and retrieve information from server
102
a
, or a database (not shown) associated with server
102
a
, at substantially any time.
As technology that facilitates wireless communications, e.g., communications over a radio frequency (RF) link, improves, the use of RF links in client/server object-oriented computing systems is increasing. RF links in client/server object-oriented computing systems are often used when a client, and even a server, are located at temporary sites and, further, may be constantly moving. For example, RF links may be used to link clients that are “out in the field,” or otherwise subject to constant relocation, to a server. Systems with clients that are out in the field generally include, but are not limited to, clients that are associated with military operations and clients that are associated with emergency activities.
As clients move, the clients may move in and out of the RF communications range of the server. Since the clients may move out of the RF communications range of the server, the RF communications links are intermittent links in that they may not always be available. Further, these links are also low-bandwidth links because the rate if data transfer is often approximately one two-hundredth of the transfer rate of cabled networks. Hence, the clients are effectively volatile clients, as they may not be in communication with the server when they attempt to request information from the server.
The ability for a client in the field to access up-to-date information may be crucial. By way of example, when a client is associated with resources which are needed in emergency activities, the client may need to know where its resources are most needed at any given time. However, if the RF link between the client and the server is not available, e.g., if the client is out of range with respect to the server, the client may not obtain updated information from the client. The inability to obtain updated, timely information may cause the resources associated with the client to be inefficiently, or even incorrectly, allocated.
Therefore, what is needed is a method and an apparatus for providing a client with updated, timely information when the client is a volatile client that is linked to a server through an intermittent link such as an RF link. In other words, what is desired is an efficient method and apparatus for allowing a client in a low-bandwidth client/server computing system to have access to updated, timely information associated with a server.
SUMMARY OF THE INVENTION
The present invention relates to maintaining updated information on client/server object-oriented computing systems. In accordance with one aspect of the present invention, a client/server object-based computing system includes a server which has a server object list that is arranged to include objects that are to be updated. The system also includes a client which has a client object list that contains an object in which the client has interest. The objects that are to be updated include the object in which the client has interest, and the server is arranged to send a message to the client that indicates that the object in which the client has interest should be updated on the client. In one embodiment, the client and the server are in communication over a low-bandwidth link.
In another embodiment, the client is further arranged to update the object in which the client has interest using a handler associated with the client. In such an embodiment, the system may also include a feed handler that is in communication with the handler and the server. The feed handler may be arranged to queue messages from the handler which are intended for the server.
According to another aspect of the present invention, a client/server object-based computing environment includes a server with a server object list and a client with a client object list, where the client communicates with the server using a client thread that is a part of the server. The server object list is arranged to include an object that is to be updated, and is further arranged to be copied into a data file that is associated with the server. The client object list includes at least one object that is of interest to the client, and the client thread is arranged to reference the server object list. In one embodiment, the server further includes a filter tree that is also referenced by the client thread. The filter tree is arranged to determine whether the object that is of interest to the client is a representation of the object that is to be updated.
In another embodiment, the client is arranged to send a request to the server through the client thread, and the server is arranged to receive the request from the client through the client thread. In such an embodiment, the request may be a request to update the server object, and the server may further be arranged to update the server object by placing the object update in the server object list.
According to still another aspect of the present invention, a method for providing a client that is a part of a client/server object-based computing system with updated object information pertaining to an object in which the client has interest includes sending a message to the client from a server that is also part of the client/server object-based computing system. The message is arranged to include updated object information. The method also includes determining whether the message is a message to update the object in which the client has inte
Arnold James F.
Casper Jeffrey
Seaton D. Scott
Shaw Scott W.
Williams Nathan W.
Beyer Weaver & Thomas LLP
Jaroenchonwanit Bunjob
Luu Le Hien
SRI - International
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