The present invention relates to a data distribution control method and a data distribution control system. More particularly, the present invention relates to a data distribution control method and a data distribution control system for controlling a data distribution network which includes a node to which an image forming apparatus is connected and a plurality of image forming apparatuses connected to the node. Nowadays, it is becoming popular to connect an image forming apparatus such as a multi function peripheral (MFP), to a network so that it can be shared by a plurality of users. In such a network system, there may be a case where a plurality of users want to access the same data at the same time. For example, the users may want to simultaneously retrieve or share image data and edit the image data using an image forming apparatus so that they can print the data on recording media such as CD sheets. If a plurality of users simultaneously access the same data, they often cannot use the data at the same time. Therefore, it may become necessary to provide a method for controlling the access so that a plurality of users can share a resource at the same time. A technique is known in which a node providing the same data to a plurality of users stores the data in a buffer and gives the data in the buffer back to a requesting node in a manner in which an exclusive use time is assigned to each user. In this technique, when a buffer is filled with data, a buffer overflow occurs. When the buffer overflows, data is discarded. Therefore, in such a technique, if a plurality of users simultaneously access the same data, data is discarded because of the buffer overflow so that a portion of data is not shared by the users. When an image forming apparatus is used as an access node, if a buffer overflow occurs, an image may not be formed, that is, the data may be lost. A buffer overflow can be prevented by limiting the access of a plurality of users to the same data. In this case, however, access requests will inevitably be lost. Moreover, since an exclusive use time is assigned to each user in this technique, a buffer cannot be efficiently used. If a plurality of users share the same data in this manner, a mechanism is also required that controls a time period during which data is held in an access node when the data is shared. If the access node has a small storage capacity, or an access request takes too much time to process, for example, when data is being inputted, data may be lost because of buffer overflow. When the access node having a small storage capacity stores data, it is preferred that the amount of the data should be managed efficiently by limiting the access to the same data. Also, in order to prevent a long waiting time from being generated, it is preferred that the access node is allowed to immediately process an access request if there are free storage spaces. A first object of the present invention is to provide a data distribution control method and a data distribution control system which are not required to use a buffer when a plurality of users share the same data. A second object of the present invention is to provide a data distribution control method and a data distribution system which allow a buffer provided in an access node to be efficiently used when data is stored in the buffer. A third object of the present invention is to provide a data distribution control method and a data distribution system which allow an access node to immediately process an access request if there are free storage spaces, while effectively preventing data loss. In order to attain the above objects, the present invention is a data distribution control method for controlling a data distribution network having a node that accesses at least one resource in a data distribution network and an image forming apparatus having a buffer for temporarily storing data, the method comprising: dividing, at the buffer, the data that is stored in the image forming apparatus to be accessible to the node, into a plurality of groups; determining the number of groups into which the data is to be divided based on one or more factors including a number of users of the image forming apparatus; registering information indicating one or more positions of a dividing point into which the data is to be divided based on the one or more factors, in a buffer entry management table that manages information indicating a plurality of buffer entry management tables of the node and an identification number of the buffer entry management table; dividing the data into a plurality of groups on a buffer by buffer basis so that the data is stored in each buffer entry of the buffer entry management table, using the information indicating the one or more positions of the dividing point; and causing the buffer entry management table to inform the node that a buffer entry has been created by giving information indicating an identification number of the buffer entry management table, an identification number of the buffer, and the information indicating the one or more positions of the dividing point, wherein the buffer entry management table manages, as an entry of a buffer entry management table that manages information about buffer entries, the information that indicates a position at which data is stored in a plurality of buffer entries of the buffer, and the information that indicates whether or not each of the plurality of buffer entries of the buffer entry management table corresponds to an image forming apparatus. The present invention is also a data distribution control system for controlling a data distribution network having a node that accesses at least one resource in a data distribution network and an image forming apparatus having a buffer for temporarily storing data, the system comprising: means for dividing, at the buffer, the data that is stored in the image forming apparatus to be accessible to the node, into a plurality of groups; means for determining the number of groups into which the data is to be divided based on one or more factors including a number of users of the image forming apparatus; means for registering information indicating one or more positions of a dividing point into which the data is to be divided based on the one or more factors, in a buffer entry management table that manages information indicating a plurality of buffer entry management tables of the node and an identification number of the buffer entry management table; means for dividing the data into a plurality of groups on a buffer by buffer basis so that the data is stored in each buffer entry of the buffer entry management table, using the information indicating the one or more positions of the dividing point; and means for causing the buffer entry management table to inform the node that a buffer entry has been created by giving information indicating an identification number of the buffer entry management table, an identification number of the buffer, and the information indicating the one or more positions of the dividing point, wherein the buffer entry management table manages, as an entry of a buffer entry management table that manages information about buffer entries, the information that indicates a position at which data is stored in a plurality of buffer entries of the buffer, and the information that indicates whether or not each of the plurality of buffer entries of the buffer entry management table corresponds to an image forming apparatus. According to the present invention, a buffer for storing data is provided in the image forming apparatus. The data in the image forming apparatus is divided into a plurality of groups, based on one or more factors. The number of groups into which the data is divided is determined based on one or more factors including the number of users of the image forming apparatus. A dividing point at which the data is to be divided into groups is registered in a buffer entry management table that manages information about buffer entries. The buffer is divided into groups on a buffer by buffer basis so that data is stored in each buffer entry of the buffer entry management table. The buffer entry management table informs the node that a buffer entry has been created by giving information indicating an identification number of the buffer entry management table, an identification number of the buffer, and information indicating the one or more positions of the dividing point, thereby controlling access to the data. When a plurality of users access the same data, no buffer is used so that data can be shared at the same time. The xe2x80x9cbufferxe2x80x9d means an image memory, a hard disk, a random access memory (RAM), a network accessible memory, or a semiconductor memory. When a plurality of users share the same data, data is divided into groups using various factors including the number of users. One group is defined by the divided data. Therefore, even if a