Electrical computers and digital processing systems: multicomput – Remote data accessing
Utility Patent
1998-07-27
2001-01-02
Kostak, Victor R. (Department: 2711)
Electrical computers and digital processing systems: multicomput
Remote data accessing
C348S086000, C714S100000
Utility Patent
active
06170006
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to video on demand (VOD) service systems, and more specifically to, in a system where a plurality of video servers are interconnected on a network, a video service system in which a video server is provided with automatic expandability and a video server and a method used for the system, and a recording medium of recording a computer program to execute the method.
2. Description of the Background Art
A VOD service system is a system in which a video server storing a picture file or data (hereinafter simply referred to as data) and a user terminal are connected through a network and the video server receives a view request of arbitrary pictures (hereinafter referred to as access) from a user through the user terminal to promptly provide the pictures to which the view request is made for the user.
Generally, even if a plurality of video servers are interconnected through a network, a certain data item is stored only in any one of the video servers. Here, in these video servers, an amount capable of accepting access is determined by their capacities.
Therefore, when accesses center on data which is stored only in a specific video server (for example, when accesses center on a popular movie, sport and the like), the load of processing is put only on the video server. Further, when the concentrated accesses exceed the acceptable amount of the above video server, the access cannot be received in such a way that the video server rejects the accesses exceeding the acceptable amount.
In order to cope with the problem, a system using a method of broadcast sending has been suggested. The broadcast sending method is a method for accumulating accesses to the same data for an arbitrary time period and performing processing to a plurality of accesses in that time period after the lapse of the time simultaneously and in parallel.
As a system with a method used by switching a provision by the above broadcast sending and a provision by normal transmission, a system is disclosed in Japanese Patent Laying-Open No. 8-18938 (hereinafter referred to as a first reference). In the method disclosed in the above first reference, first (when the number of accesses is one), data is provided for an access origin by a supplying method by normal transmission, and when other accesses to the same data follow, by switching to the broadcast sending from the time, the data is also provided for the other access origins.
On the other hand, as described above, a certain data item is stored only in any one of the video servers. Therefore, when the corresponding data is not stored in a specific video server to which the user accesses, it is required to search all of the other video servers except the specific video server connected on the network for a video server in which the corresponding data is stored.
As a video server searching method, “LOCATING RESOURCES IN COMPUTER NETWORKS” disclosed in U.S. Pat. No. 4,914,571 (hereinafter referred to as a second reference) is known.
However, in the searching method disclosed in the above second reference, when the corresponding data exists only in a video server at a distant location requiring a lot of transmission time, response capabilities to users become deteriorated. Further, in the searching method disclosed in the above second reference, when the corresponding data does not exist in any of the video servers on the network (due to data updating and the like), searches of the entire network will result, causing a problem that a response to the access (a response that no data to which a view request is made exists) cannot be transmitted within a system-guaranteed time in a wide area network.
Therefore, the system using the searching method disclosed in the above second reference may disadvantageously impair the characteristic of the VOD service system that a user can see pictures whenever the/she wants.
In order to cope with the problem, a system has been developed such that each video server holds and manages information about a title and a storage location of data stored in each video server (hereinafter referred to as title information). By this system, it is possible to quickly determine in which video server the data corresponding to the access by the user is stored, allowing a prompt response to the access from the user.
The above title information is provided for the user terminals of the VOD service system as a title menu.
However, as described above, in the conventional general VOD service system, when accesses center on a specific video server to exceed the acceptable amount of the video server, some users disadvantageously cannot make accesses.
Further, in the system using the broadcast sending method, since it is required to wait for an arbitrary time period, the time of use for the user is restricted and the characteristic of the VOD service system may be disadvantageously impaired as such that a user can see pictures whenever he/she wants.
Further, in the system disclosed in the above first reference, data is provided from some midpoint for the access except the first access.
On the other hand, in the above system using a method of holding and managing the title information, when a new data item is added or a stored data item is deleted, the specific video server to which addition/deletion is made updates its own title information, while the other video servers are not notified of the update contents in the specific video server and therefore do not update the title information.
Therefore, the user who is connected to the other video servers accesses based on the old title information without being updated. Thus, the user may disadvantageously receive the service without knowing the existence of added data and access data which has been already deleted.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a VOD service system capable of providing a comfortable VOD service for users without impairing a characteristic of the VOD service system by improving expandability of data among video servers and title information as to the data, a video server and a method used for the system, and a recording medium for recording a computer program to execute the method.
The present invention has the following features to achieve the object described above.
A first aspect is directed to a VOD service system in which a plurality of video servers and a plurality of user terminals are connected through a network, the system for receiving access from the user terminals and then providing data stored in the video server for the user terminals,
each of the video servers comprising:
access amount managing means for managing an amount of the access from the user terminals; and
data copy processing means for copying specific data to at least one other video server when the access amount managing means determines that the amount of the access exceeds a predetermined amount.
As described above, in accordance with the first aspect, the video server manages the amount of access of its own, and copies specific data to another video server when the amount of access exceeds the predetermined amount.
Therefore, in the first aspect, even when accesses center only on a specific video server, the system is automatically expanded, and thus it is possible to provide a comfortable VOD service to more users without rejecting access due to an exceeded acceptable amount or giving restriction on transmission timing to the users.
According to a second aspect, the data copy processing means in the first aspect transmits notification of a request for copy permission of the specific data to the at least one video server, and further receives a response of copy permission or prohibition to the notification from the at least one other video server to determine whether it is possible to copy the specific data.
As described above, in accordance with the second aspect, the data copy processing means in the first aspect copies the specific data after receiving permission from another video server.
Kostak Victor R.
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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