Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data transfer regulating
Reexamination Certificate
2001-04-18
2003-04-08
Meky, Moustafa M. (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data transfer regulating
C709S230000, C709S231000, C709S233000, C709S234000, C709S235000, C709S236000, C709S237000
Reexamination Certificate
active
06546428
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to communications between devices over a network. More particularly, the present invention relates to communications over a low-speed or wireless communication link between two computers using a message queue.
BACKGROUND OF THE INVENTION
Traditional mainframe computer configurations provided for user interface to the computer through computer terminals which were directly connected by wires to ports of controllers connected by channels to the mainframe computer. As computing technology has evolved, processing power has typically evolved from a central processing center with a number of relatively low-processing power terminals to a distributed environment of networked processors. Examples of this shift in processing include local or wide area networks which interconnect individual work stations where each workstation has substantial independent processing capabilities. This shift may be further seen in the popularity of the Internet which interconnects many processors and networks of processors through devices such as, for example, routers.
At the same time that processing power was becoming more distributed there was also an increase in the popularity of mobile computing. The use of laptops, notebooks, Personal Digital/Communication Assistants (PDAs/PCAs) and other portable devices has led to an increase in demands for wireless communications. Wireless communication allows a user freedom to move within the wireless environment while remaining “connected” to a network. Furthermore, a wireless connection to a network allows a portable processor user the convenience of connecting to a network without having to plug into a docking station or use some other method of “hardwiring” to a network. However, wireless wide area networks, cellular communications and packet radio, suffer from common limitations such as the high cost per byte of communications, slow response time, low bandwidth and unreliability which all hamper use of wireless technology.
Even outside of the portable processing arena wireless communications have seen an increase in popularity. Thus, as a result of infrastructure limitations, cost or convenience, it is becoming more frequent that a network linking two devices wishing to communicate may include a low through-put component such as a wireless network link.
Communications between devices such as computers are typically disadvantaged particularly on lower through-put network legs, such as wireless legs (or highly congested legs which are effectively bandwidth limited), where bandwidth limitations result in slower response time for communications between the computers. In the extreme, protocol timeouts may even cause transmission errors and resulting retransmissions or even inability of the communication system to operate. Thus, utilizing wireless technology, or any low-speed communication technology, for data communication between applications executing on computers exacerbates the weaknesses of the wireless technology.
Communications are further complicated where a plurality of applications executing on a computer perform operations requiring transmission of data streams over a shared port to an external communication link, on occasion with interruptions in session connections. It is known to provide for this shared access using asynchronous message queuing systems such as International Business Machine Corporation's Message Queuing Series (“MQSeries”), Telecommunications Access Method (“TCAM”), or Information Management Systems (“IMS”), which enable applications to queue data for transport (transmission) to a partner destination computer device on an external communication link such as a network. Using asynchronous message queuing, the external connection between the source computer and the destination computer typically does not have to exist at the time of submission of a data stream message for transmission and the source or sending device is not required to synchronously wait for a response from the destination device. In other words, the transmitting application hands over responsibility for the message to the transport queuing application which takes on responsibility for eventually delivering the queued message. In general, any data object, including messages, files, images, containers, etc., can be transported using a message queuing system.
The message queue transport application reads messages from the queue and sends them to the destination devices over the network. The communication protocol between transmitting and receiving message queues provides for assumption of responsibility over a transmitted message by the receiving device. The source message queue transport application typically then frees the queue space occupied by a message once confirmation is received that the receiving device has assumed responsibility for the message.
OBJECTS AND SUMMARY OF THE INVENTION
In view of the above limitations, it is one object of the present invention to provide for improved performance for data communications in a low-speed communication environment such as wireless communications.
It is a further object of the present invention to support such communications where the communicating applications may be only intermittently connected.
It is an additional object of the present invention to support such communications where the external communication link used for communication is shared by different applications.
In view of these and other objects, the present invention provides methods, systems and computer program products supporting differencing data communications using a message queue supporting asynchronous communications from a variety of applications executing on a source device over a shared external communication link to destination devices. At least one segment of a data stream between the application on the source device and an application on the destination device occurs over an external communication link. The present invention provides increased communications performance by combining data stream differencing with asychronous message transmission control using a message queue. The data stream is segmented based on the type of the data stream to provide a logical segmentation which increases the occurrence of repeated transmissions of a segment. Each segment is then placed in the message queue as a message for transport to a destination computer. Differencing is provided by replacing the segment with an associated identifier for segments which have previously been transported to provide a reduced volume of data for transmittal based on recognition and replacement of data segments which have previously been transmitted by the source device.
The intercept system on the receiving end at the destination computer receives the transmitted reduced segments as messages, expands the reduced segments and writes the expanded segments to a receive message queue. Segments are read from the receive message queue and combined to form the reconstructed data stream. The reconstructed data stream is then provided to the target application on the destination computer. By providing protocol conversion at both ends of the external communication link, the applications may continue to operate without any need to recognize the protocol differencing conversion provided by the present invention. Furthermore, synchronization is not required between the devices as the message queue provides asynchronous communications and, if a reduced segment is not recognized, retransmission of the complete segment using the segment identifier may be requested and the source device creates and queues the segment as a message.
In one embodiment of the present invention, a method is provided for differencing data communications using a message queue. A data stream having an associated type is intercepted (received) from a host application prior to transmission of the data stream through the message queue on an external communication link to a destination computer. The data stream is segmented based on the associated type to prov
Baber Stephen B.
Britton Kathryn H.
Hind John R.
Housel, III Barron C.
Wesley Ajamu Akinwunmi
Edelman Bradley
Meky Moustafa M.
Myers Bigel & Sibley & Sajovec
Ray-Yarletts Jeanine S.
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