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Data transfer scheme for reducing network load using general purpose browser on client side

1. Field of the Invention

The present invention relates to data transfer device and method.

2. Description of the Related Art

The client-server type information system having a server for providing various services on a network and a client for requesting services to the server is widely used. The World Wide Wed system (referred hereafter as Web) for carrying out communications by utilizing the HTTP (HyperText Transfer Protocol) on the Internet is the very widely used client-server type information system. Normally, in the Web, a server program is operated on the server and a prescribed program such as a Web browser is operated on the client.

In the client-server type information system such as Web, the services are provided by the communications between the client and the server. Consequently, the communication bandwidth between the client and the server tends to become a bottleneck of the entire system For this reason, the cache technique is usually used for the purpose of reducing the network load.

In the case or the Web, the Web browser or the like that is operated on the client often utilizes the cache function, to cache recently accessed data. In the Web system, the access is made by specifying the information or the service by a URL (Uniform Resource Locator), so that the cache on the client stores those which are cachable among data returned as results of requesting the information or the service to the Web server in the past, in the cache in correspondence to their URLs. Then, when there is a request for the information or the service of the same URL as that presents in the cache, that data is returned such that the communication with the server can be eliminated, as long as it is possible to judge that the data in the cache is not obsolete yet.

Also, in the case of using LAN (Local Area Network), the cache function is often provided at a proxy server that is provided between the LAN and the Internet. The cache of the client described above is a cache dedicated to the user of that client, but the cache of the proxy server on the LAN is operated as a cache snared by a plurality of users, so that the cache works even in the case of accessing the URL that was accessed by the other client in the past.

The caching targets of these caches are static contents. In the past, many of the information and the services disclosed on the Web are largely static contents for which the information updating frequency is not very high and which are disclosed to the unspecified many, so that the checking of the presence/absence of the cache on the basis of URL was sufficiently effective.

However, as the system in which the user uses the Web browser to access the information and the service on the server via the network such as the Web based ASP (Application Service Provider) becomes widespread, the data that cannot be handled by the above described cache technique are increasing.

In order to deal with such problems, the cache technique using a fingerprint (FP) compression has been proposed in the commonly assigned, co-pending U.S. patent application Ser. No. 10/092,540.

In the U.S. patent application Ser. No. 10/092,540, the FP compression processing is carried out between a proxy server on the client side (CSP: Client Side Proxy) and a proxy server on the Web server side (SSP: Server Side Proxy), so that two proxy servers are necessary and there has been a problem that the network configuration becomes complicated.

For example, in the case of the portable terminal utilizing the Mobile IP technique, the communication path from the portable terminal to the Web server and the communication path from the Web server to the portable terminal are different so that it is difficult to use the CSP.

It is therefore an object of the present invention to provide a data transfer scheme capable of reducing the network load, by using a general purpose browser on the client side, without requiring a separate CSP between the SSP and the client.

According to one aspect of the present invention there is provided a data transfer device for transferring a request received from a client to a server which is a destination of the request, and transferring contents data according to the request received from the server to the client that is a source of the request, comprising: a reception unit configured to receive the request from the client and the contents data from the server; a transmission unit configured to transmit the request to the server and the contents dam to the client; a feature quantity calculation unit configured to calculate a feature quantity indicating a feature of the contents data, upon receiving the contents data in response to the request; a memory unit configured to store the feature quantity and the contents data in correspondence; a search unit configured to search through the memory unit to check whether the feature quantity identical to a new feature quantity calculated by the feature quantity calculation unit is stored in the memory unit or not, and output a search result; and a control unit configured to control the search unit to carry out a search, determine information to be transmitted from the transmission unit according to the search result, and control the transmission unit to transmit to the client a reply message formed by a header portion and a body portion, which contains the feature quantity in the body portion, when the feature quantity identical to the new feature quantity is stored in the memory unit, or control the transmission unit to transmit to the client the reply message which contains the contents data and the new feature quantity in the body portion, while storing the new feature quantity and a corresponding contents data in the memory unit when the feature quantity identical to the new feature quantity is not stored in the memory unit.

According to another aspect of the present invention there is provided a data receiving and displaying device, comprising: a transmission unit configured to transmit a request to a data transfer device; a reception unit configured to receive a reply message formed by a header portion and a body portion, according to the request from the data transfer device; an analysis unit configured to analyze the reply message and carry out processing according to a message format; a display unit configured to display processed data; a memory unit configured to store a contents data and a feature quantity in correspondence, when the reply message contains the contents data and the feature quantity in the body portion as a result of analysis by the analysis unit; a search unit configured to search through the memory unit to check whether the feature quantity identical to the feature quantity contained in the reply message is stored in the memory unit or nor and output a search result, when the reply message contains the feature quantity but no contents data in the body portion as a result of analysis by the analysis unit, and acquire the contents data corresponding to the feature quantity from the memory unit and output the contents data to the analysis unit, when the feature quantity identical to the feature quantity contained in the reply message is stored in the memory unit as a result of search by the search unit; and a contents data composition unit configured to acquire the contents data having the feature quantity identical to the feature quantity contained in the reply message by transmitting the request from the transmission unit to the data transfer device, and output the contents data to the analysis unit, when the feature quantity identical to the feature quantity contained in the reply message is not stored in the memory unit as a result of search by the search unit.

According to another aspect of the present invention there is provided a computer program product to be installed at a data receiving and displaying device using a computer and having a transmission unit configured to transmit a request to a data transfer device, a reception unit configured to receive a reply message formed by a header portion and a body portion, according to the request from the data transfer device, an analysis unit configured to analyze the reply message and carry out processing according to a message format, and a display unit configured to display processed data, the computer program product comprising: a first computer program code for causing the computer to store a contents data and a feature quantity in correspondence into a memory, when the reply message contains the contents data and the feature quantity in the body portion as a result of analysis by the analysis unit; a second computer program code for causing the computer to search through the memory to check whether the feature quantity identical to the feature quantity contained in the reply message is stored in the memory or not and output a search result, when the reply message contains the feature quantity but no contents data in the body portion as a result of analysis by the analysis unit and acquire the contents data corresponding to the feature quantity from the memory and output the contents data to the analysis unit, when the feature quantity identical to the feature quantity contained in the reply message is stored in the memory as a result of search; and a third computer program code for causing the computer to acquire the contents data having the feature quantity identical to the feature quantity contained in the reply message by transmitting the request from the transmission unit to the data transfer device, and output the contents data to the analysis unit, when the feature quantity identical to the feature quantity contained in the reply message is not stored in the memory as a result of search.

According to another aspect of the present invention there is provided a data transfer method for transferring a request received from a client to a server which is a destination of the request, and transferring contents date according to the request received from the server to the client that is a source of the request, comprising: calculating a feature quantity indicating a feature of the contents data, upon receiving the contents data in response to the request; storing the feature quantity and the contents data in correspondence into a memory; searching through the memory to check whether the feature quantity identical to a new feature quantity calculated by the calculating step is stored in the memory or not; transmitting to the client a reply message formed by a header portion and a body portion, which contains the feature quantity in the body portion, when the feature quantity identical to the new feature quantity is stored in the memory; and transmitting to the client the reply message which contains the contents data and the new feature quantity in the body portion, while storing the new feature quantity and a corresponding contents data in the memory, when the feature quantity identical to the new feature quantity is not stored in the memory.

Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings.