Electrical computers and digital processing systems: multicomput – Computer-to-computer data modifying
Reexamination Certificate
1999-04-22
2002-07-02
Geckil, Mehret B. (Department: 2152)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data modifying
C709S238000, C709S249000
Reexamination Certificate
active
06415331
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a server system used in a data communication system, more particularly, to a server system having update means for data which is held in a gateway server.
2. Description of the Related Art
In recent years, the use of a mobile communication system outdoors utilizing radio communication such as a PHS (Personal Handy Phone System) attracts attention of businessmen. However, a problem arises in that when radio data communication is performed, a poor quality of the communication often causes disconnection of a line. Although the disconnected line results only in a temporary interruption of sound in voice communication, it leads to loss of data in data communication.
In this case, retransmission control is generated, and the line is disconnected at the worst. In such a case, since all of application data become invalid, transmission and reception must be performed again from the beginning. This procedure for another transmission and reception can be performed several times depending on a communication state, thereby making a system very troublesome for a user to utilize.
For addressing this problem, recently, communication middleware is commercially available which enables, even if the line has been disconnected, transmission and reception to be restarted from a portion of data subsequent to a portion of the data previously received when the line is recovered after the disconnection. Description will be made on a system configuration and a communication sequence for prior art communication middleware with reference to FIG.
1
and FIG.
2
.
FIG. 1
is a schematic block diagram of a communication system provided with a gateway server having middleware and is used in common with description of the prior art and the present invention.
FIG. 2
shows a communication sequence for the prior art communication system in FIG.
1
.
As shown in
FIG. 1
, a typical communication system comprises radio client
101
; radio base station
102
for connection to radio network
104
; dial-up router
103
for connection to LAN
107
; gateway server
105
implementing communication middleware; application server
106
realizing electronic mail, World Wide Web, or the like; and LAN
107
.
In
FIG. 1
, gateway server
105
and application server
106
independently exist on the same network. However, gateway server
105
and application server
106
do not necessarily exist on the same network and both of them may exist on the same hardware. Radio client
101
and dial-up router
103
are connected using a PPP (Point-to-point protocol) and the communication middleware exists on a TCP/IP or UDP/IP protocol.
Next, an operation will be described using FIG.
2
. First, radio client
101
connects a line with dial-up router
103
, and after the completion of the connection, provides connection request
1101
for a communication connection at a communication middleware level to gateway server
105
and receives connection acknowledgment
1102
for communication connection from gateway server
105
.
FIG. 2
shows a case where data is transmitted from application server
106
to radio client
101
. First, radio client
101
provides application data request
1103
, then application server
106
transmits data for which the request is provided in response to the request. Packets to be transmitted are given sequence numbers and an ACK packet can be used to check to which point data has been transmitted.
FIG. 2
shows a case where the line is disconnected after data packets with sequence number
3
or later become unable to be transmitted while being transmitted from the gateway server due to a reduced receiving level in a radio wave area or the like. After the line is disconnected, radio client
101
reconnects the line with dial-up router
103
, and after the completion of the reconnection, transmits reconnection request
1104
for connection to gateway server
105
. At this time, the sequence numbers of data packets received correctly by radio client
101
are also notified. Gateway server
105
, after the completion of processing for reconnection, transmits acknowledgment message
1105
to radio client
101
. Thereafter, gateway server
105
retransmits data from the data packet with sequence number
3
which has not been received by radio client
101
and receives reception acknowledgment
1106
from radio client
101
to terminate a sequence of operations.
In this case, if the communication middleware is not implemented, it is required to request data again from the server to transmit the data from the beginning after the connection is established.
However, the prior art communication middleware has the following disadvantages. The first disadvantage is that if a line is disconnected during the reception of data for which a real-time characteristics are important and later an attempt is made to restart communication with the middleware from some midpoint in the data, the latest data can not be transmitted. This is because in the prior art communication middleware the application data accumulated at the gateway server with the communication middleware comes to be out of the control of the application server. Even when data has been updated to the latest version at the application server, the old application data accumulated at the gateway server with the communication middleware for which transmission has stopped can not be updated to the latest version so that the gateway server must transmit the old data without updating. The latest data is not transmitted unless there is another data request from the radio client.
The prior art will be described using FIG.
1
. Even when the data packets (data packets with sequence numbers
3
to
5
in this prior art) to be transmitted at the time the reconnection processing is executed after the disconnection of the line have been updated to the latest version in application server
106
, the data packets already accumulated in gateway server
105
are not under control of the application so that these accumulated data packets can not be discarded to update to the latest version. Thus, when the latest data packets are required, they must be transmitted after the accumulated data packets are transmitted.
Therefor if information such as monitoring information and traffic information for which the real-time characteristics are required is not updated until after the data packets accumulated in the gateway server have been transmitted, causing a problem in providing real-time service.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of updating accumulated data with middleware and a server system for performing the same, which can maintain real-time characteristics for information and improve efficiency of a line. To achieve this, time information of a data packet waiting for retransmission is looked up and it is determined whether data in a higher layer is new or old by inquiring of an application server about whether it is the latest or not, thereby making is possible always to transmit the latest data to a client terminal when a line reconnection is generated.
A method of updating accumulated data with middleware according to the present invention is a method of updating accumulated data with middleware in a data communication system connecting a client and an application server through a gateway server having the middleware. A gateway server receives specified data from the application server in response to a data request from the client, holds the data in a buffer, adds a predetermined header to the data, and transmits the data to the client. When the client has not been able to receive all of the specified data, the client requests reconnection to the gateway server. The gateway server, receiving the reconnection request, retransmits the data held in the buffer to the client if the data under transmission has not been updated in the application server. While, the gateway server which received the reconnection request updates the data under trans
Foley & Lardner
Geckil Mehret B.
NEC Corporation
LandOfFree
Method of updating accumulated data with middleware and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of updating accumulated data with middleware and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of updating accumulated data with middleware and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2884225