Abstract:
Provided is a web page distribution system capable of distributing web pages that satisfy the output condition of a distribution target. The web page distribution system comprises a plurality of mobile phones and a web page distribution server. The mobile phones can communicate with Internet and have individually set output conditions for outputting all web pages including text data and image data referred to from the text data. The web page distribution server specifies, based on the reception of the distribution request for the web pages, the output conditions of the mobile phones and determines whether the web pages satisfy the specified output conditions or not. When it is determined that the output conditions are not satisfied, the web page distribution server converts the web pages that do not satisfy the output conditions into the ones that satisfy the output conditions and performs a process for distributing the web pages.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a Web page distribution system that converts Web pages into converted Web pages in accordance with capabilities of a destination device to which the Web pages is to be distributed, and transmits the converted Web pages to the destination device. 
       BACKGROUND 
       [0002]    Generally, destination devices, such as mobile phones, to which Web pages to be distributed, may require different output conditions on a receivable Web page, such as description language used to describe a Web page, saving format of Web page component data such as image data configuring a Web page, total data size of a Web page that is a sum of data size of document part of the Web page and data size of component part of the Web page, and display size that is limited by a size of display device of a destination device. 
         [0003]    For example, a simple Web page, that contains just a document without any special font attribute and with no accompanying image data, may meet all of the above mentioned output conditions. 
         [0004]    Some of destination devices may be capable of interpreting Web pages with rich contents such as large number of images, movies, animations, advanced layouts such multiple columns, and so on. In general, users of destination devices with such a high capabilities expect to browse Web pages with rich contents. Accordingly, if it is allowed to distribute Web pages with rich contents, the Web pages can attract more users of high-spec destination devices. 
         [0005]    However, it is impossible to prepare Web pages with rich contents that meet all possible output conditions that may be required by any destination device. Accordingly, when the same Web pages with rich contents are distributed to destination devices with different capabilities, some of the destination devices cannot display the Web pages with rich contents. 
         [0006]    If different versions of same Web pages with rich contents are prepared to meet the output conditions of each of different types of destination devices, the above-mentioned problem is solved. However, the solution requires for hosts of Web pages to prepare a large number of different versions of the Web pages in accordance with number of different possible output conditions that may be required by any destination device, and it is a heavy burden of the hosts of Web pages. 
         [0007]    In the above-explained situation, a Web page distribution system that automatically converts Web pages to make the Web pages meet output conditions required by destination devices of the Web pages is proposed. (See, for example, Patent Literature 1.) The Web page distribution system has a distribution sever and a relay sever. Hosts of Web pages with rich contents are required to register only the original version of their Web pages to the distribution server. When the relay server relays distributions of Web pages from the distribution server to destination devices of the Web pages, the relay server automatically converts the original version of Web pages to a converted version of Web pages that meet output conditions required by the destination devices. 
         [0008]    In the conversion of Web pages at the relay server, conversions between description languages of the Web pages, for example, conversions of saving formats of Web page component data such as image data, conversions of total data sizes of the Web pages, namely sums of data size of document part and data size of component part of the Web pages, and conversions of display sizes of Web page components such as image are executed. 
         [0009]    As one of the methods for converting total data sizes of Web pages, i.e. sums of data size of document part and data size of component part of the Web pages, for example, Patent Literature 1 proposes a method to reduce a total data size of Web page by dividing the Web page into plural small Web pages. According to the method, the divided Web pages can be distributed one by one to a destination device, and total data size of a Web page distributed to the destination device at the same time could be reduced. As another method for converting total data sizes of Web pages, for example, Patent Literature 2 proposes a method to reduce a total data size of Web page by executing image conversion processing to make a display size of Web page content (image) smaller, to degrade quality, such as number of colors, of Web page content (image), and so on. 
       SUMMARY OF THE INVENTION 
       [0010]    Historically, attention has not been paid to data size of each Web page component data. In such methods, document parts of Web pages are modified to change the display sizes of images in the Web pages in accordance with capabilities of destination devices, and image data itself is not changed. Accordingly, sizes of image data are not reduced. Therefore, when a data size of one set of image data is larger than a data capacity of a destination device, the destination device cannot display the image. 
         [0011]    Moreover, according to such known methods, when a size of one set of image data is smaller than the data capacity of the destination device, and a sum of sizes of two sets of image data is larger than the data capacity, each of the two images are displayed in different divided Web pages. In the case, a user of the destination device may feel inconvenient since it is difficult for the user to understand the whole structure of the original Web page from many small divided Web pages. 
         [0012]    According to these proposed methods, data size of each of image data is converted, but data size of document part of a Web page is not changed. Accordingly, total data size of a Web page including data size of document part may exceeds the data capacity of the destination device, and the destination device may not display the Web page. 
         [0013]    Moreover, in these known methods, total sum of data sizes of converted image data sets in a Web page is not checked. Accordingly, total data size of the converted Web page that is a sum of data size of document part and data sizes of converted image data sets may exceed the data capacity of the destination device, and the destination device may not display the Web page. 
         [0014]    In addition, attention has not been paid to load distribution at the relay server. In general, load distribution at a relay server is achieved by installing plural relay servers and one load balancing server between a distribution server and destination devices. From a destination device, components of the system is connected in the following order: destination device, load balancing server, selected one of plural relay servers, and selected one of plural distribution servers. 
         [0015]    An outline of general flow of load distribution processes will be explained here. In the above-explained system, each time when the load balancing server receives a request for a certain Web page from a destination device, the load balancing server selects one of the plural relay servers, and relays the request to the selected relay server. The selected relay server further relays the request to one of the distribution servers, and receives a Web page transmitted from the distribution server in response to the request. When the relay server receives the Web page, the relay server converts the Web page in accordance with capability of the destination device, and transmits the converted version of Web page to the load balancing server. The load balancing server relays the converted version of Web page from the relay server to the destination device. 
         [0016]    When the distributed Web page is accompanied by rich contents, plural times of data communications are usually required between the distribution server and the destination device. Since such a Web page usually contains document part and one or more component data sets of Web page such as images, and each of the document part and component data sets needs separate data communications between the distribution server and the destination device. Accordingly, first the document part of Web page is distributed to the destination device, and then component parts of Web page are distributed to the destination device one by one. 
         [0017]    As explained above, the load balancing server selects one of the plural relay servers each time when the load balancing server receives a request for a certain Web page from a destination device, and relays the request to the selected relay server. Accordingly, a relay server that relays a document part of a Web page and a relay server that relays a component part such as image of the same Web page may not be different. From a view point of efficiency of load distribution, it is preferable for different relay servers to relay the document part and each of the component parts. 
         [0018]    A relay server that reduces total data size of a Web page by executing image conversion processing to Web page component data (image data), such as a relay server, analyzes Web page document data when the relay server relays the Web page document data, i.e. when the relay server executes the first data communication among a series of plural data communications for relaying each component of the Web page, lists up all of the Web page component data sets (image data sets) in the Web page, obtains all of the Web page component data sets from any one of the distribution servers, and applies image conversion processing to the data sets, in advance. Then, the relay server transmits the Web page component data sets (image data sets) that were obtained and converted in advance to the destination device that requests the Web page, without further accessing the distribution servers. 
         [0019]    By obtaining the Web page component data sets (image data sets) in advance, the total time for completing transmits of all of the data sets of Web page, i.e. the Web page text data set and all of the Web page component data sets, can be shortened compared to obtaining and converting each of the Web page component data sets each time when a certain Web page component data set is requested from the destination device. 
         [0020]    When the relay server to obtain and convert all of the Web page component data sets in advance, the destination device receives all of the converted Web page component data sets from the same relay server, since the converted Web page component data sets are available only from the relay server that converted the Web page document data. 
         [0021]    On the other hand, a load balancing server does not care whether a relay server that relays a Web page text data set and relay servers that relay Web page component data sets (image data sets) are the same device or not. If it is necessary for one relay server to obtain and convert the Web page text data set and all of the Web page component data sets of the same Web page, process flows of the load balancing server and the relay servers must be modified. Moreover, when such a modification is made in the system, efficiency of load distribution becomes lower than that of a normal load distribution system. 
         [0022]    Accordingly, an owner of Web page distribution system needs to bear a heavy burden of expenses to modify the system, and at the same time the owner has to accept the demerit that high efficiency of load distribution cannot be expected. 
         [0023]    In the above explained situation, the present invention is aimed to provide a Web page distribution system that distributes Web pages meeting various output conditions required by each of destination devices. 
         [0024]    To solve the above-mentioned problems, the present invention provides, as a first embodiment, 
         [0025]    a Web page distribution system comprising: 
         [0026]    a distribution server (Web distribution server  1 ) having a communication unit (CPU executing processes in steps S 108  and S 204 ) that executes data communications via a network (Internet  3 ) and transmits a Web page data set ( 10 ), the Web page data set containing a Web page text data set ( 11 ) indicating a text described in a predetermined Web page description language and one or more Web page component data sets (image data sets  12 ) referred to by the text, and 
         [0027]    plural destination devices (mobile phones  2 ), each of the plural destination devices being capable of displaying a Web page in accordance with the Web page data set received from the distribution server via the network, each of the plural destination devices having a set of output conditions defining requirements on a Web page data set for letting a Web page displayed at the destination device, 
         [0028]    the distribution server having: 
         [0029]    a specifying unit (CPU executing processes in step S 101 ) that specifies one set of output conditions in accordance with a request for the Web page data set, the request being transmitted from one destination device among the plural destination devices, 
         [0030]    a judging unit (CPU executing processes in steps S 102 , S 104  and S 106 ) that judges whether the Web page data set meets the one set of output conditions specified by the specifying unit, and 
         [0031]    a converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) that converts the Web page data set to a converted Web page data set meeting the one set of output conditions when the judging unit judges that the Web page data set fails to meet the one set of output conditions. 
         [0032]    The present invention also provides, as a second embodiment, 
         [0033]    a Web page distribution system of the first embodiment, wherein: 
         [0034]    the judging unit (CPU executing processes in step S 106 ) judges that the Web page data set ( 10 ) fails to meet the one set of output conditions when a total data size of the Web page data set exceeds a predetermined maximum data size, and 
         [0035]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0036]    a data size minimizing unit (CPU executing processes in step S 301 ) that converts at least one of the one or more Web page component data sets (image data sets  12 ) to a small sized Web page component data set (small sized image data set  13 ) with a small data size, and 
         [0037]    a text modifying unit (CPU executing processes in step S 302 ) that converts the Web page text data set ( 11 ) to a modified Web page text data set indicating a text that originally refers to at least one of the one or more Web page component data sets to refer to at least one of the small sized Web page component data sets that are generated by the data size minimizing unit. 
         [0038]    The present invention also provides, as a third embodiment, 
         [0039]    a Web page distribution system of any one of the first and the second embodiments, wherein: 
         [0040]    the judging unit (CPU executing processes in step S 106 ) judges that the Web page data set ( 10 ) fails to meet the one set of output conditions when a total data size of the Web page data set exceeds a predetermined maximum data size, and 
         [0041]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0042]    a data size minimizing unit (CPU executing processes in step S 301 ) that converts at least one of the one or more Web page component data sets (image data sets  12 ) to a small sized Web page component data set (small sized image data set  13 ) with a small data size, 
         [0043]    a data size changing unit (CPU executing processes in step S 304 ) that converts at least one of the one or more Web page component data sets to a middle sized Web page component data set (middle sized image data sets  14   a  to  15   a ) with a data size that is larger than a data size of the small sized Web page component data set and smaller than a data size of the Web page component data set, and 
         [0044]    a text modifying unit (CPU executing processes in step S 305 ) that converts the Web page text data set ( 11 ) to a modified Web page text data set indicating a text that originally refers to at least one of the one or more Web page component data sets to refer to at least one of the small sized Web page component data sets or at least one of the middle sized Web page component data sets. 
         [0000]    The present invention also provides, as a fourth embodiment, 
         [0045]    a Web page distribution system of the third embodiment, wherein: 
         [0046]    the one or more Web page component data sets (image data sets  12 ) contained in the Web page data set ( 10 ) are plural, and 
         [0047]    the text modifying unit (CPU executing processes in step S 302 ) converts the Web page text data set ( 11 ) by modifying the text that originally refers to at least one of the plural Web page component data sets to refer to at least one of the middle sized Web page component data sets (middle sized image data sets  14   a  to  15   a ) in an order of being displayed in a Web page at the one destination device (mobile phone  2 ). 
         [0048]    The present invention also provides, as a fifth embodiment, 
         [0049]    a Web page distribution system of any one of the third and the fourth embodiments, wherein: 
         [0050]    the data size changing unit (CPU executing processes in step S 304 ) repeats the conversion from the one or more Web page component data sets (image data sets  12 ) to the middle sized Web page components data sets (middle sized image data sets  14   a  to  14   b ) without exceeding a predetermined maximum number of times of conversions. 
         [0051]    The present invention also provides, as a sixth embodiment, 
         [0052]    a Web page distribution system of any one of the first to the fifth embodiments, wherein: 
         [0053]    the judging unit (CPU executing processes in step S 106 ) judges that the Web page data set ( 10 ) fails to meet the one set of output conditions when a total data size of the Web page data set exceeds a predetermined maximum data size, and 
         [0054]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0055]    a data size minimizing unit (CPU executing processes in step S 301 ) that converts at least one of the one or more Web page component data sets (image data sets  12 ) to a small sized Web page component data set (small sized image data set  13 ) with a small data size, and 
         [0056]    a text modifying unit (CPU executing processes in step S 308 ) that converts the Web page text data set ( 11 ) by modifying the text that originally refers to at least one of the plural Web page component data sets to refer to at least one of the small sized Web page component data sets or at least one of special sized Web page component data sets (white image data sets), each of the special sized Web page component data sets being prepared in advance with a data size smaller than a data size of a corresponding one of the small sized Web page component data sets. 
         [0057]    The present invention also provides, as a seventh embodiment, 
         [0058]    a Web page distribution system of the sixth embodiment, wherein: 
         [0059]    the one or more Web page component data sets (image data sets  12 ) contained in the Web page data set ( 10 ) are plural, and 
         [0060]    the text modifying unit (CPU executing processes in step S 308 ) converts the Web page text data set ( 11 ) by modifying the text that originally refers to at least one of the plural Web page component data sets (image data sets  12 ) to refer to at least one of the special sized Web page component data sets (white image data sets) in an inverse order of being displayed in a Web page at the one destination device (mobile phone  2 ). 
         [0061]    The present invention also provides, as an eighth embodiment, 
         [0062]    a Web page distribution system of any one of the sixth and the seventh embodiments, wherein: 
         [0063]    a text modifying unit (CPU executing processes in step S 311 ) that converts the Web page text data set ( 11 ) by modifying the text that originally refers to at least one of the plural Web page component data sets (image data sets  12 ) to refer to at least one of the small sized Web page component data sets (small sized image data sets  13 ), at least one of the special sized Web page component data sets (white image data sets), or at least one of substitute text data sets, each of the substitute text data sets being prepared in advance with a data size smaller than a data size of a corresponding one of the special sized Web page component data sets. 
         [0064]    The present invention also provides, as a ninth embodiment, 
         [0065]    a Web page distribution system of the eighth embodiment, wherein: 
         [0066]    the one or more Web page component data sets (image data sets  12 ) contained in the Web page data set ( 10 ) are plural, and 
         [0067]    the text modifying unit (CPU executing processes in step S 311 ) converts the Web page text data set ( 11 ) by modifying the text that originally refers to at least one of the plural Web page component data sets (image data sets  12 ) to refer to at least one of the substitute text data sets in an inverse order of being displayed in a Web page at the one destination device (mobile phone  2 ). 
         [0068]    The present invention also provides, as a tenth embodiment, 
         [0069]    a Web page distribution system of any one of the first to the ninth embodiments, wherein: 
         [0070]    the judging unit (CPU executing processes in step S 104 ) judges that the Web page data set fails to meet the one set of output conditions when a display size of any one of images indicated by the one or more Web page component data sets (image data sets  12 ) exceeds a predetermined maximum display size, and 
         [0071]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0072]    a display size reducing unit (CPU executing processes in step S 105 ) that converts at least one of the one or more Web page component data sets (image data sets  12 ) to a small display sized Web page component data set (small sized image data sets  13 ) indicating an image with the predetermined maximum display size, and 
         [0073]    a text modifying unit (CPU executing processes in step S 105 ) that converts the Web page text data set ( 11 ) to a modified Web page text data set indicating a text that originally refers to at least one of the one or more Web page component data sets to refer to at least one of the small display sized Web page component data sets. 
         [0074]    The present invention also provides, as an eleventh embodiment, 
         [0075]    a Web page distribution system of any one of the first to the tenth embodiments, wherein: 
         [0076]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0077]    a component data converting unit (CPU executing processes in steps S 301  and S 304 ) that converts at least one of the one or more Web page component data sets (image data sets  12 ) to a converted Web page component data set, and 
         [0078]    a text modifying unit (CPU executing processes in steps S 105 , S 107 , S 302 , S 308 , S 311  and S 305 ) that converts the Web page text data set ( 11 ) to a modified Web page text data set indicating a text that originally refers to at least one of the one or more Web page component data sets to refer to at least one of the converted Web page component data sets, and adds to the Web page text data set at least one parameter data set indicating a parameter to be used for a conversion executed by the component data converting unit to generate a converted Web page text data set, and 
         [0079]    the communication unit transmits the converted Web page text data set (Web page text data set  11  containing conversion parameters) in response to the request for the Web page data set ( 10 ) transmitted from the one destination device (mobile phone  2 ), and transmits the converted Web page component data set generated by the component data converting unit in response to a request for a Web page component data set with the parameter data set. 
         [0080]    The present invention also provides, as a twelfth embodiment, 
         [0081]    a Web page distribution system of any one of the first to the eleventh embodiments, wherein: 
         [0082]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0083]    a data storing unit that stores converted Web page component data sets (small sized image data sets  13 , middle sized image data sets  14   a  to  14   b ) that are generated by the converting unit, and 
         [0084]    the converting unit (CPU executing processes in step S 203  when a result of judgment made in step S 202  is negative) converts one Web page component data set among the one or more Web page component data sets to generate a converted Web page component data set when the data storing unit does not store a converted Web page component data set generated from the one Web page component data set. 
         [0085]    The present invention also provides, as a thirteenth embodiment, 
         [0086]    a Web page distribution system of any one of the first to the twelfth embodiments, wherein: 
         [0087]    the judging unit (CPU executing processes in step S 102 ) judges that the Web page data set fails to meet the one set of output conditions when the text indicated by the Web page document data ( 11 ) includes at least one of character strings that are predetermined as original character strings to be substituted with predetermined substitute character strings, and 
         [0088]    the converting unit (CPU executing processes in steps S 103 , S 105 , S 107  and S 203 ) has 
         [0089]    a text modifying unit (CPU executing processes in step S 203 ) that converts the Web page text data set by substituting at least one of the original character strings with at least one of the substitute character strings that corresponds to the at least one of the original character strings without analyzing a context of the original text to generate a converted text described in a Web page description language that the one destination device can interprets. 
         [0090]    The present invention also provides, as a fourteenth embodiment, 
         [0091]    a Web page distribution system of any one of the first to the thirteenth embodiments, wherein: 
         [0092]    the distribution server (Web page distribution server  1 ) is realized by a computer that executes data processing following instructions in a Web page distribution server application of a prior art and instructions in an add-in program (text data conversion module  101 , image data conversion module  102 ) combined to the Web page distribution server application. 
         [0093]    In the Web page distribution system of the first embodiment of the present invention, a distribution server distributes a converted Web page data set meeting output conditions required by a destination device that request for the Web page. 
         [0094]    In the Web page distribution system of the second embodiment of the present invention, the distribution server distributes a converted Web page data set that contains small sized Web page component data sets and that has a smaller data size than a data capacity of the destination device of the Web page. 
         [0095]    In the Web page distribution system of the third embodiment of the present invention, the distribution server distributes a converted Web page data set containing, in addition to the small sized Web page component data sets, middle sized Web page component data sets with higher qualities than those of the small sized Web page component data sets. Accordingly, by the Web page distribution system, the destination device can receive a Web page containing Web page component data sets that have comparatively high quality, though the data size of the converted Web page data set is smaller than the data capacity of the destination device of the Web page. 
         [0096]    In the Web page distribution system of the fourth embodiment of the present invention, the distribution server distributes a converted Web page data set containing, in addition to the small sized Web page component data sets, the middle sized Web page component data sets with higher qualities than those of the small sized Web page component data sets, in an order of being displayed in the Web page. Accordingly, by the Web page distribution system, the destination device can receive a Web page data set that contains Web page component data sets with comparatively high quality in respect of images that are shown in the upper part of the Web page and comparatively important, and that has a smaller data size than the data capacity of the destination device. 
         [0097]    In the Web page distribution system of the fifth embodiment of the present invention, the distribution server executes conversions within a limited number of times, for example five times, in respect of one Web page data set to generate a converted Web page data set. Accordingly, by the Web page distribution system, a large number of Web page data sets that are converted so that they could meet output conditions of destination devices can be quickly distributed to the destination devices since the conversion processes for each Web page data set do not require a heavy burden or a long time. 
         [0098]    In the Web page distribution system of the sixth embodiment of the present invention, the distribution server distributes a converted Web page data set containing, in addition to the small sized Web page component data sets, special sized Web page component data sets with smaller data sizes than those of the small sized Web page component data sets. Accordingly, by the Web page distribution system, the destination device can receive a converted Web page data set that has a smaller data size than the data capacity of the destination device. 
         [0099]    In the Web page distribution system of the seventh embodiment of the present invention, the distribution server distributes a converted Web page data set containing, in addition to the small sized Web page component data sets, the special sized Web page component data sets with smaller data sizes than those of the small sized Web page component data sets, in an inverse order of being displayed in the Web page. Accordingly, by the Web page distribution system, the destination device can receive a Web page that does not show some of images in the lower part of the Web page that are comparatively unimportant, and that has a smaller data size than the data capacity of the destination device. 
         [0100]    In the Web page distribution system of the eighth embodiment of the present invention, the distribution server distributes a converted Web page data set containing, in addition to the small sized Web page component data sets, the special sized Web page component data sets with smaller data sizes than those of the small sized Web page component data sets, and substitute text data sets with smaller data sizes than those of the special sized Web page component data sets. Accordingly, by the Web page distribution system, the destination device can receive a converted Web page data set that has a smaller data size than the data capacity of the destination device. 
         [0101]    In the Web page distribution system of the ninth embodiment of the present invention, the distribution server distributes a converted Web page data set containing, in addition to the small sized Web page component data sets and the special sized Web page component data sets, the substitute text data sets with smaller data sizes than those of the special sized Web page component data sets, in an inverse order of being displayed in the Web page. Accordingly, by the Web page distribution system, the destination device can receive a Web page that does not show some of images in the lower part of the Web page that are comparatively unimportant, and that has a smaller data size than the data capacity of the destination device. 
         [0102]    In the Web page distribution system of the tenth embodiment of the present invention, the distribution server distributes a Web page data set that contains Web page component data sets indicating images with original display sizes in respect of images with display sizes that are the same as or smaller than a maximum display size of the destination device, and contains converted Web page component data sets indicating images with display sizes that are the same as or smaller than the maximum display size in respect of images with display sizes that are larger than the maximum display size. Accordingly, by the Web page distribution system, the destination device can receive a Web page that shows images with their original display sizes in their original layouts, and that shows images with their converted display sizes in layouts different from their original layouts, so that they are shown in the limited display sizes. Namely, in the Web page displayed at the destination device, changes in the layouts of images are minimized under the condition of maximum display size. 
         [0103]    In the Web page distribution system of the eleventh embodiment of the present invention, the distribution server that receives a request for a Web page component data set also receives a parameter data set indicating a parameter to be used for a conversion of the Web page component data set. Accordingly, even when a load balancing server is installed to the system and a distribution server receiving a request for a Web page component data set is different from a distribution server receiving a request for a Web page text data set, the distribution server receiving the request for the Web page component data set can convert the Web page component data set to generate a converted Web page component data set, and distributes the converted Web page component data set. Namely, the distribution server receiving the request for the Web page text data set and the distribution server receiving the request for the Web page component data set are not required to share the converted Web page component data set. In the result, an efficient load distribution can be achieved. 
         [0104]    In the Web page distribution system of the twelfth embodiment of the present invention, the distribution server does not have to repeat conversion processes in respect of a Web page component data set that was converted in the past. Accordingly, total burden and total time required for conversions of Web page component data sets are reduced, and a large number of converted Web page data sets that meet output conditions of destination devices can be distributed quickly. 
         [0105]    In the Web page distribution system of the thirteenth embodiment of the present, the distribution server generates a converted Web page text data set indicating a text described in a Web page description language that can be interpreted by each of destination devices by executing simple substitutions following a substitution table that indicates correspondences between original character strings and substitute character strings, and distributes the converted Web page text data set. Since no grammatical analysis is executed in the substitution processes, once the converted Web page text data set is generated, the converted Web page text data set may be used with high probability even after the original Web page text data set is edited to comply with grammatical rules of its Web page description language that are newly introduced or modified. 
         [0106]    In the Web page distribution system of the fourteenth embodiment of the present, the distribution server is realized by an add-in program to a Web page distribution server program that is generally used. In other words, a general Web server can become the distribution server of the present invention by installing a module program to the general Web server. Accordingly, without installing new servers such as relay servers, the Web page distribution system that provides distribution of converted Web page data sets that meet output conditions of destination devices can be realized. Moreover, since total load can be distributed to each of plural distribution servers that are easily increased, load distribution can be easily achieved. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0107]      FIG. 1  illustrates an outline of a Web page distribution system of an exemplary embodiment of the present invention. 
           [0108]      FIG. 2A  illustrates examples of output conditions of Web pages. 
           [0109]      FIG. 2B  illustrates examples of attributes of a Web page. 
           [0110]      FIG. 2C  illustrates examples of attributes of converted images in a Web page. 
           [0111]      FIG. 2D  illustrates examples of attributes of a white image and a substitute text used as substitutes of images in a Web page. 
           [0112]      FIG. 3  illustrates examples of attributes of converted Web pages generated by the Web page distribution system of the exemplary embodiment of the present invention. 
           [0113]      FIG. 4A  illustrates a flow of processes for distributing Web pages in the exemplary embodiment of the present invention. 
           [0114]      FIG. 4B  illustrates a flow of processes for distributing images in Web pages in the exemplary embodiment of the present invention. 
           [0115]      FIG. 5  illustrates a flow of processes for converting character strings and images in Web pages in the exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0116]    Exemplary embodiments of the present invention are explained below. 
         [0117]    In the following explanation of the exemplary embodiments of the present invention, figures are used for facilitating understanding of the explanation.  FIG. 1  illustrates a whole composition of a Web page distribution system in accordance with exemplary embodiment 1 of the present invention. 
         [0118]    The Web page distribution system includes Web page distribution servers  1   a ,  1   b , . . . , that are connected to Internet  3 , mobile phones  2  that are carried by users, load balancing server  4  that distributes load caused by data accessing to Web page distribution servers  1   a ,  1   b, . . . .    
         [0119]    The plural Web page distribution servers  1   a ,  1   b , . . . have the same constitution and functions, and they store the same sorts of data sets. 
         [0120]    Web page distribution servers  1   a ,  1   b , . . . , are server computers that are generally known, and each of them has a CPU (Central Processing Unit, not shown), ROM (Read Only Memory, not shown), RAM (Random Access Memory, not shown), a communication unit (not shown) that conducts data communications with other devices via load balancing server  4 , and a storing unit (not shown) that is a magnetic recording device such as a hard disk. 
         [0121]    The storing unit (not shown) of each of Web page distribution servers  1   a ,  1   b , . . . , stores, as shown in  FIG. 1 , Web page data sets  10  including text data sets  11  and image data sets  12 , Web server program  103  that instructs distributions of Web page data sets  10  in response to requests for Web page data sets  10  from mobile phones  2 , text data conversion module  101  that is an add-in program combined with Web server program  103  and instructs conversions of text data sets  11 , and image data conversion module  102  that instructs conversions of image data sets  12 . The number of image data set(s)  12  may be zero or more. 
         [0122]    The storing unit (not shown) of each of Web page distribution servers  1   a ,  1   b , . . . , also stores terminal device data sets that indicate output conditions with regard to mobile phones  2 . Each of the terminal device data sets includes device model identifying data set identifying a device model of mobile phone  2  such as a model number, and output condition data set in association with the device model identifying data set. The output condition data set will be explained later with reference to  FIG. 3A . 
         [0123]    Image data sets  12  play roles of the Web page component data sets of the present invention. Text data conversion module  101  plays a role of the text modifying unit of the present invention. Image data conversion module  102  plays roles of the data size minimizing unit and the data size changing unit. Web server program  103  plays a role of a normal program that instructs distributions of Web page data sets of the present invention. 
         [0124]    Each of mobile phones  2  is a normal mobile phone that primarily has CPU (Central Processing Unit, not shown), ROM (Read Only Memory, not shown), RAM (Random Access Memory, not shown), a communication unit (not shown) that conducts data communications with other devices via Internet  3 , and displaying unit  201  that is a display device such as a liquid crystal display device. 
         [0125]    The storing unit (ROM, not shown) of each of mobile phones  2  stores a Web browser program that instructs mobile phone  2  to transmit distribution requests for Web page data sets  10  to Web page distribution servers  1   a ,  1   b , . . . , and to display Web pages following received Web page data sets  10  transmitted in response to the requests. 
         [0126]    Load balancing server  4  a special computer for server functions that can perform high-speed processing and that primarily has CPU (Central Processing Unit, now shown), ROM (Read Only Memory, not shown), RAM (Random Access Memory, not shown), a communication unit (not shown) that conducts data communications with other devices via Internet  3 , and a storing unit (not shown) that is a magnetic recording device such as a hard disk. Load balancing server  4  is generally sold as an expensive load balancing device that is composed of dedicated hardware. 
         [0127]    The storing unit (not shown) of load balancing server  4  stores a load distribution program that instructs load balancing server  4  to distribute requests for distributing Web page data sets  10  sent from mobile phones  2  to Web page distribution servers  1   a ,  1   b , . . . , in accordance with predetermined criteria. The predetermined criteria include, for example, balance of numbers of data accesses to each of Web page distribution servers  1   a ,  1   b , . . . , speeds of data processing of them, etc. 
         [0128]    Load distribution function is a function that is usually utilized when the system needs to handle a large number of distribution requests for Web page data sets  10  at the same time. For example, when Web page distribution servers  1  are two, each of them is required to handle only a half of the distribution requests. 
         [0129]    Web page data sets  10  of the present embodiment are explained below. 
         [0130]    Each of Web page data sets  10  includes text data set  11  and image data sets  12 . The number of image data sets  12  may be zero or more. Text data set  11  indicates a text that is described in a predetermined Web page description language such as HTML (HyperText Markup Language). In the Web page description language (such as HTML), image data sets  12  indicating images included in a Web page are described as referred data sets by use of IMG tags. 
         [0131]    Distribution requests for Web page data sets  10  of the present embodiment are explained below. 
         [0132]    In accordance with instructions of the Web browser program, a mobile phone  2  transmits a distribution request for a Web page data set to Web server  103  in response to a certain operation made to the mobile phone  2  by a user of the mobile phone  2  as shown in  FIG. 1 . The distribution request includes data that specifies a certain Web page data set  10  in Internet  3  (such as URL, Universal Resource Locator). Web server  103  specifies the certain Web page data set  10  on the basis of the data specifying Web page data set  10  (URL). Then, Web server  103  specifies a text data set  11  included in the specified Web page data set  10 , and transmits the specified text data set  11  to the mobile phone  2 . 
         [0133]    The mobile phone  2  following instructions of the Web browser program receives the text data set  11 , and transmits distribution requests for image data sets  12  to Web server  103  when the text data set  11  includes references of image data sets (IMG tags) to the image data sets  12 . Each of the references of image data sets (IMG tags) includes data (URL) specifying a name of data file (file name) of an image data set  12 . Each of the distribution requests for image data sets  12  transmitted from the mobile phone  2  includes a file name of an image data set. 
         [0134]    Web server  103  specifies image data sets  12  on the basis of file names included in the distribution requests, and transmits the specified image data sets  12  to the mobile phone  2 . 
         [0135]    One distribution request is transmitted for one image data set  12 . Accordingly, the same number of data communications as the number of images included a Web page shown in accordance with a Web page data set  10  are conducted between the mobile phone  2  and Web server  103 . 
         [0136]    In short, a distribution request for a Web page data set  10  is comprised of a distribution request for text data set  11  and a distribution request for image data sets  12 . 
         [0137]    Load distribution of distribution requests for Web page data sets  10  of the present embodiment is explained below. 
         [0138]    Load balancing server  4  selects one of Web page distribution servers  1   a ,  1   b , . . . , as a destination of a distribution request, each time when load balancing server  4  receives a distribution request for a text data set  11  or a distribution request for an image data set  12 . Accordingly, as shown in  FIG. 1 , a Web page distribution server  1  that handles a distribution request for a text data set  11  and a Web page distribution server  1  that handles a distribution request for an image data set  12  may be different. For example, Web page distribution server  1   a  may handle a distribution request for a text data set  11 , Web page distribution server  1   b  may handle a distribution request of a first image data set  12 , and Web page distribution server  1   a  may handle a distribution request for a second image data set  12 , etc. 
         [0139]    Output conditions for Web page data sets  10  of the present embodiment are explained below. 
         [0140]    A Web page is shown by the Web browser function of mobile phone  2  following instructions indicated by a Web page data set  10 . Technologies used for producing mobile phones  2  have been constantly improved, and therefore, performances of hardware such as CPUs (not shown), RAMs (not shown) and ROMs (not shown) of old models, current models and future models of mobile phones  2  are different from one another. 
         [0141]    Moreover, programs installed to mobile phones  2  are designed to meet with hardware configurations of mobile phones  2 , and therefore, programs installed to different mobile phones  2  having different hardware become different from each other. Accordingly, for example, a Web browser of a mobile phone  2  that has a lower performance can handle only a Web page data set that has a smaller total data size, and a mobile phone  2  that has a smaller display size cannot display an image with a larger display size in one screen. 
         [0142]    Moreover, programs installed to mobile phones  2  may be designed separately by different companies to meet with conditions given by, for example, different manufactures of mobile phones  2 . Accordingly, for example, specifications and requirements of Web page description languages given for two mobile phones  2  that are designed to access to different mobile communication networks managed by different carriers may be different. 
         [0143]    Namely, one Web page data set  10  that can be interpreted by a Web browser function of one mobile phone  2  to show a Web page may not be interpreted by a Web browser function of another mobile phone  2 . In other words, different output conditions may be required on each of different models of mobile phone  2  having a Web browser function. 
         [0144]    In the present embodiment, each of output conditions on Web page data sets  10  consists of, for example, a Web page description language, a size of display unit  201  (resolution), and a maximum total size of a Web page data set  10  that can be handled by the mobile phone  2 . A total size of a Web page data set  10  is a sum of a data size of a text data set  11  and data sizes of image data sets  12 , a number of which may be zero or more, of the Web page data set  10 . 
         [0145]    Web page data sets  10  and output conditions of them of the present embodiment are further explained below. 
         [0146]      FIG. 2B  shows an example of a set of attributes of Web page data sets  10 . In connection with the Web page data set  10  shown in  FIG. 2B , a description language of the Web page data set  10  is HTML 1 , a data size of a text data set  11  contained in the Web page data set  10  is 5 KB (kilo bytes), a data size of a first image data set  12  referred to by the text data set  11  is 85 KB, a display size of an image indicated by the first image data set  12  is 120 pixels length and 150 pixels width, a data size of a second image data set  12  referred to by the text data set  11  is 30 KB, a display size of an image indicated by the second image data set  12  is 50 pixels length and 40 pixels width, a data size of a third image data set  12  referred to by the text data set  11  is 80 KB, a display size of an image indicated by the third image data set  12  is 300 pixels length and 300 pixels width, and a total data size of the Web page data set  10  is 200 KB. 
         [0147]    Three exemplary sets of output conditions of Web page data sets  10  for mobile phones  2  are explained below. 
         [0148]    As shown in  FIG. 2A , according to the first set of output conditions, a required Web page description language is HTML 1 , a required display size is 320 pixels length and 240 pixels width, and a required maximum total data size is 100 KB. Under the conditions, the Web page data set  10  shown in  FIG. 2B  does not meet the requirements in respect that the width of display size of the third image is too large (300 pixels length/300 pixels width) and the total data size is too large (200 KB). 
         [0149]    Accordingly, mobile phones  2  with the first set of output conditions usually output error messages when they try to display the second image in the Web page in accordance with the Web page data set  10  shown in  FIG. 2B . 
         [0150]    As shown in  FIG. 2A , according to the second set of output conditions, a required Web page description language is HTML 2 , a required display size is 320 pixels length and 240 pixels width, and a required maximum total data size is 50 KB. Under the conditions, the Web page data set  10  shown in  FIG. 2B  does not meet the requirements in respect that the Web page description language is different (HTML 2 ), the width of display size of the third image is too large (300 pixels length/300 pixels width), and the total data size is too large (200 KB). 
         [0151]    Accordingly, mobile phones  2  with the second set of output conditions usually display only some parts of the Web page that are shown following instructions commonly used in both of HTML 1  and HTML 2  and/or display a screen with a layout that is different from the original one, as well as they output error messages when they try to display the first image in the Web page in accordance with the Web page data set  10  shown in  FIG. 2B . 
         [0152]    As shown in  FIG. 2A , according to the third set of output conditions, a required Web page description language is HTML 3 , a required display size is 160 pixels length and 120 pixels width, and a required maximum total data size is 5 KB. Under the conditions, the Web page data set  10  shown in  FIG. 2B  does not meet the requirements in respect that the Web page description language is different (HTML 3 ), the width of display size of the first image is too large (120 pixels length/150 pixels width), the width of display size of the third image is too large (300 pixels length/300 pixels width), and the total data size is too large (200 KB). 
         [0153]    Accordingly, mobile phones  2  with the third set of output conditions usually display only some parts of the Web page that are shown following instructions commonly used in both of HTML 1  and HTML 3  and/or display a screen with a layout that is different from the original one, as well as they output error messages when they try to display the first image in the Web page in accordance with the Web page data set  10  shown in  FIG. 2B . 
         [0154]    To display the Web page completely in accordance with the Web page data set  10  shown in  FIG. 2B , it is necessary to convert the original Web page data set  10  to a converted Web page data set that meets the output conditions of mobile phone  2  in respect of each of mobile phones  2 . More concretely, a conversion of the text data set  11  (text conversion) and conversions of the image data sets  12  (image conversions) in the Web page data set  10  are required. 
         [0155]    A series of processes for a conversion of a Web page data set in the present embodiment are explained below. 
         [0156]    First, a series of processes for a text conversion executed in accordance with instructions of text data conversion module  101  are explained below. 
         [0157]    A text conversion in the present embodiment primarily contains two parts of conversion processes. The first part of conversion processes are for a conversion of Web page description languages of the text data set  11 , and the second part of conversion processes are for conversions of references (IMG tags) to image data sets in the text data set  11 . 
         [0158]    In the first part of the conversion processes for a conversion of Web page description languages of the text data set  11 , some character strings indicated by the text data set  11  are converted to their substitute character strings following a Web page description language of a target mobile phone  2 . 
         [0159]    More concretely, a substitute table listing original character strings in accordance with an original Web page description language and their substitute character strings in accordance with a substitute Web page description language is prepared in advance, and the substitutions of character strings are executed on the basis of the substitute table. 
         [0160]    The original character strings in the substitute table are selected, for example, by providers of Web page distribution servers  1   a ,  1   b , . . . , from among character strings used in text data sets  10  of Web page data sets  10  distributed from the Web page distribution servers based on specifications of Web page description languages used for the original text data sets  10  and specifications of other Web page description languages possibly adopted in mobile phones  2 . In the present embodiment, the original Web page description language is HTML 1 , and the other Web page description languages possibly adopted in mobile phones  2  are HTML 2  and HTML 3 . In this case, the original character strings to be converted are selected from among character strings used in HTML 1 . 
         [0161]    It should be noted that, in the present embodiment, the text conversion processes are executed only by matching character strings without grammatical analysis of the original text indicated by the text data set  11 . Such grammatical analysis cannot be realized by simply using the substitute table but they require a complex program that can instruct analysis of contexts including the original character strings, etc. 
         [0162]    Since the simple method of text conversion using the substitute table is adopted in the present invention, it has a merit that there is no need to modify a program for analyzing grammars of texts indicated by text data sets  11  even when specifications of a Web page description language used for describing the texts are changed and only some modifications to the substitute table are required. 
         [0163]    In the second part of the conversion processes for conversions of references to images (IMG tags) in the text indicated by the text data set  11 , a total of a data size of the text data set  11  and data sizes of image data sets  12  referred to by the references (IMG tags) in the text data set  11  is calculated, and it is judged whether the calculated total data size exceeds the maximum total size of the target mobile phone  2 . In a case when the total data size does not exceed the maximum total data size, no conversion of references (IMG tags) is executed. 
         [0164]    On the other hand, in a case when the total data size exceeds the maximum total data size, conversions of the image data sets  12  are actually executed as explained later and a total data size is checked on the basis of the converted image data sets, and the references (the IMG tags) in the text indicated by the text data set  11  is converted so that the text refers to the converted image data sets. More concrete explanation of the conversion of references to image data sets (IMG tags) will be given in a later part of this description. It should be noted that, in the present embodiment, conversions of image data sets are actually executed in respect of all of the images to check data sizes of the converted image data sets and a Web page data set  10  requiring a total data size less than the maximum total data size of the target mobile phone  2  is certainly generated even when the text data set  11  includes plural references to image data sets. 
         [0165]    Next, a series of processes for image conversions executed in accordance with instructions of image data conversion module  102  are explained below. 
         [0166]    In the image conversions of the present embodiment, qualities of images are converted to one of plural preset grades of quality.  FIG. 2C  shows an example of such a plural preset grades of quality. In accordance with the example shown in  FIG. 2C , five grades of image quality are totally given, i.e. image data set  12  that is an image data set with the original image quality without conversion, middle sized image data sets  14   a  to  14   c  that are image data set with image qualities categorized to a middle quality, and small sized image data set  13  that is an image data set with an image quality categorized to a low quality. 
         [0167]    Any number of grades of image quality may be categorized to the middle quality. 
         [0168]    Small sized image data set  13  indicates an image with the lowest image quality to minimize its data size. Small sized image data set  13  is actually generated in accordance with parameters of a format in which the image data set is saved, such as 1% degradation that means making the quality of image 1% lower than to the quality of the original image in JPEG (Joint Photographic Experts Group), 2 bits that means using only two bits for specifying colors in GIF (Graphics Interchange Format), etc. By the conversion to small sized image data set  13 , for example, the data size of the first image is decreased from 85 KB to 20 KB, the data size of the second image is decreased from 30 KB to 8 KB, and the data size of the third image is decreased from 80 KB to 19 KB, as shown in  FIG. 2C . 
         [0169]    The extent to which the image quality should be degraded to reduce the data size may be determined, for example, the providers of Web page distribution servers  1   a ,  1   b , . . . , on their own criteria. 
         [0170]    Middle sized image data sets  14   a  to  14   c  are image data sets with image quality that is higher than that of small sized image data set  13  and lower than that of image data set  12 . Middle quality image data sets are also generated in accordance with parameters of formats in which the image data sets are saved, such as 0.2% to 0.6% degradation in JPEG (Joint Photographic Experts Group), etc. By the conversion to middle sized image data sets  14   a  to  14   c , for example, the data size of the first image is decreased from 85 KB to 70 KB, 50 KB or 34 KB, the data size of the second image is decreased from 30 KB to 24 KB, 18 KB or 12 KB, and the data size of the third image is decreased from 80 KB to 64 KB, 48 KB or 19 KB, as shown in  FIG. 2C . 
         [0171]    The above explained conversions of image data sets may be executed at one of two timings. Namely, first, the image data conversions may be executed when Web page distribution servers  1   a ,  1   b , . . . , receives a distribution request for text data set  11  from a mobile phone  2  and calculates a total data size required for displaying a Web page, in response to the request. In the case, the image data conversion is executed in accordance with instructions of image data conversion module  102  that are called by instructions of text data conversion module  101 . Second, the image data conversions may be executed when Web page distribution servers  1   a ,  1   b , . . . , receives a distribution request for image data set  12  from a mobile phone  2  and distributes an image data set in response to the request. In the case, the image data conversion is executed in accordance with instructions of image data conversion module  102  that are directly called. 
         [0172]    The storing unit (not shown) of each of Web page distribution servers  1   a ,  1   b , . . . , stores image data sets  12 ,  12 ,  14   a  to  14   c , and image data conversion module  102  instructs the Web page distribution server to generate the image data sets only when they are not saved in the storing unit. 
         [0173]    In some cases, even after image data sets  12  are converted to small sized image data set  13  or middle sized image data sets  14   a  to  14   c  and the converted image data sets are referred to by text data set  11 , the total data size required for displaying a Web page still exceeds the maximum total data size. 
         [0174]    For example, when a target mobile phone  2  requires output condition  2  shown in  FIG. 2A , a total data size of the text data set  11  of the Web page data set  10  and small sized image data sets  13  for the Web page data set  10  exceeds the maximum total data size of the target mobile phone  2 . 
         [0175]    In such a case, it is an option to drop the image from the Web page. However, when the image is dropped, the layout or design of Web page that is originally indicated by the Web page data set  10  cannot be maintained when the Web page is displayed in the target mobile phone  2 . 
         [0176]    In the above mentioned case, the references to the image data sets  12  (IMG tags) are modified so that they refer to white image data sets each of which indicates a white image with 1 pixel length and 1 pixel width having a really small data size. In the modification, display sizes of the white images are maintained as the same display sizes as those of the original images. Accordingly, the layout of the Web page is maintained when it is displayed in the target mobile phone  2  though the images are not shown in the Web page. 
         [0177]    There are still some cases where a total data size required for displaying a Web page exceeds a maximum total data size of a target mobile phone  2  even when all of references to image data sets (IMG tags) are modified so that they refer to white image data sets. 
         [0178]    For example, when a target mobile phone  2  requires output condition  3  shown in  FIG. 2A , the data size of the text data set  11  of the Web page data set  10  is nearly equal to the maximum total data size of the target mobile phone  2 , and there is no enough room for allowing any image data set  12  to be handled by the target mobile phone  2 . 
         [0179]    In the above mentioned case, the references to the image data sets  12  (IMG tags) are modified so that they refer to substitute text data sets each of which indicates a text of an explanation of the image to be substituted shown at the same position as that of the image in the Web page. A substitute text data set has a still smaller data size than that of a white data set. Accordingly, the explanations of the images are shown in the Web page in the target mobile phone  2  though the images are not shown and the original layout is not maintained. 
         [0180]    In the present embodiment, a substitute text data set (ALT attribute) included in each of references to image data sets (IMG tags) that are originally included in text data set  11  is used as the above mentioned substitute text data set. When ALT attribute is not found in the original text data set  11 , a default text data set indicating a general explanation such as “image  1 ” is used as the substitute text data set.\ 
         [0181]    A data size of a substitute text data set depends on a length of the text indicated by the substitute text data set. However, since one character requires only a several bytes of data size, a data size of a normal substitute text data set is estimated around ten bytes (0.01 KB) as shown in  FIG. 2D . 
         [0182]      FIG. 4A  shows a flow of processes executed by any one of Web page distribution servers  1   a ,  1   b , . . . , for distributing a Web page data set  10  in response to a distribution request from a mobile phone  2 . 
         [0183]    As explained above, a distribution request for a Web page data set  10  consists of a distribution request for text data set  11  and distribution requests for image data sets  12 , and the distribution request for text data set  11  is transmitted from a mobile phone  2  before the distribution requests for image data sets  12 . Accordingly, a process for distributing a text data set  11  is executed first. 
         [0184]    When one of Web page distribution server  1   a ,  1   b , . . . , receives a request for Web page data set  10  from a mobile phone  2 , the Web page distribution server  1  extracts a device model identifying data set identifying a device model of the mobile phone  2  from the distribution request for Web page data set  10 , and specifies a set of output conditions of the device model of the mobile phone  2 , in step S 101 . 
         [0185]    In the next step, i.e. step S 102 , the Web page distribution server  1  selects a suitable substitute table of Web page description languages on the basis of information on the Web page description language of the mobile phone  2  indicated by the output conditions, and judges whether any of the original character strings in the selected substitute table is included in a text indicated by the text data set  11  that is to be distributed to the mobile phone  2 . 
         [0186]    When no original character string in the substitute table is included in the text, the Web page distribution server  1  proceeds to step S 104 . 
         [0187]    When any original character string in the substitute table is included in the text indicated by the text data set  11  to be distributed to the mobile phone  2 , the Web page distribution server  1  proceeds to step S 103 , and substitutes all character strings in the text that are also included in the substitute table as the original character strings with their corresponding substitute character strings. Then, Web page distribution server  1  proceeds to step S 104 . 
         [0188]    In step S 104 , the Web page distribution server  1  specifies a maximum display size indicated by the output conditions, and judges whether all of display sizes of image data sets  12  that are referred to in the text data set  11  do not exceed the maximum display size. 
         [0189]    In step S 104 , when all of display sizes of image data sets  12  do not exceed the maximum display size, the Web page distribution server  1  proceeds to step S 106 . 
         [0190]    In step S 104 , when any one of display sizes of image data sets  12  exceeds the maximum display size, the Web page distribution server  1  proceeds to step S 105  and executes image data conversions so that a display size of any of the converted image data set(s) does not exceed the maximum display size. Then, Web page distribution server  1  proceeds to step S 106 . 
         [0191]    In step S 106 , the Web page distribution server  1  specifies a maximum data size indicated by the output conditions, and judges whether a total data size required to display the Web page, i.e. a sum of a data size of the text data set  11  to be distributed and data sizes of image data sets  12  referred to by the text data set  11 , does not exceed the maximum data size. 
         [0192]    In step S 106 , when the total data size does not exceed the maximum data size, the Web page distribution server  1  proceeds to step S 108 . 
         [0193]    In step S 106 , when the total data size exceeds the maximum data size, the Web page distribution server  1  proceeds to step S 107  and executes conversions of the text data set  11  and the image data sets  12 . Details of the conversions of text data set and image data sets will be explained with reference to  FIG. 5  in a later part of this description. After step S 107 , the Web page distribution server  1  proceeds to step S 108 . 
         [0194]    In step S 108 , the Web page distribution server  1  distributes the converted text data set  11  that meets the output conditions to the mobile phone  2 . 
         [0195]      FIG. 5  shows a flow of processes of conversions of the text data set and the image data sets executed in step S 107   
         [0196]    In step S 301 , the Web page distribution server  1  executes the small sized image data set conversions in connection with all of the image data sets  12  that are referred to by the text data set  11  of the Web page, and generates small sized image data sets  13 . Then, the Web page distribution server  1  proceeds to step S 302 . 
         [0197]    In step S 302 , the Web page distribution server  1  changes a reference to image data set  12  (IMG tag) in the text data set  11  so that it refers to a small sized image data set  13  converted from the image data set  12 . In each step S 302 , the Web page distribution server  1  select one reference to an image data set  12  (IMG tag) in an inverse order of displays of images in the Web page, and replace the selected reference with a new reference to a small sized image data set  13 . 
         [0198]    Reference to image data sets (IMG tags) contained in text data set  11 , which are described in a Web page description language, are explained below. Image data sets  12  indicate images and saved in data files. Accordingly, the references to the image data sets refer to the image data sets  12  by indicating file names of them. For example, when a file name of an original image data set is “xxx.jpg”, a reference to the image data set is described as an IMG tag indicating the file name of image data set like “&lt;img src=“xxx.jpg”&gt;”. 
         [0199]    References to small sized image data sets  13  are explained below. Similarly to the reference to image data sets  12 , references to small sized image data sets  13  are described as IMG tags indicating file names of the small sized image data sets  13 . For example, when a file name of a small sized image data set  13  is “xxx_in.jpg”, a reference to the small sized image data set  13  is described like “&lt;img src=“xxx_min.jpg”&gt;”. 
         [0200]    In the present embodiment, a file name of a small sized image data set is created by combining a file name of its original image data set and characters indicating a parameter used for the conversion to generate the small sized image data set. For example, when the parameter used for the conversion is “min” that specifies a conversion to generate a small sized image data set, a file name created for the small sized image data set is, for example, “xxx.jpg?min” and the reference to the small sized image data set (IMG tag) is described like &lt;img src=“xxx.jpg?min”&gt;. 
         [0201]    In other words, in step S 302 , the file name contained in the reference to the image data set  12  (IMG tag) in the text data set  11  is replaced with a file name that is created by adding, to the original file name of image data set  12 , characters identifying a parameter of conversion to generate a small sized image data set such as “?min”. 
         [0202]    In the next step, i.e. in step S 303 , the Web page distribution server  1  specifies a maximum data size indicated by the output conditions, and judges whether a total data size that is a sum of a data size of the text data set  11  to be distributed and data sizes of image data sets  12  and  13  referred to by the text data set  11 , does not exceed the maximum data size. 
         [0203]    In step S 303 , when the total data size does not exceed the maximum data size, the Web page distribution server  1  proceeds to step S 304 . 
         [0204]    In step S 303 , when the total data size exceeds the maximum data size, the Web page distribution server  1  proceeds to step S 307  and checks whether all of the original references to the image data sets  12  (IMG tags) in the text data set  11  have already been replaced with new references to image data sets  13 . 
         [0205]    In step S 307 , when all of the original references have already been replaced with the new references, the Web page distribution server  1  proceeds to step S 307 . 
         [0206]    In step S 307 , when some of the original references have not been replaced with the new references yet, the Web page distribution server  1  returns to step S 302 , and replaces the next original reference to image data set  12  (IMG tag) in the inverse order of display of images in the Web page with a new reference to image data set  13 . Then, the Web page distribution server  1  repeats step S 303  and the steps following step S 303 . 
         [0207]    In each step S 308 , the Web page distribution server  1  selects one reference to a small sized image data set (IMG tag) in the text data set  11  in the inverse order of displays of images in the Web page, and replaces the reference to the small sized image data set with a reference to a white image data set. Namely, each time when step S 308  is executed, a reference to small sized image data sets  13  (IMG tag) in the text data set  11  is replaced with a reference to a white image data set one by one in the inverse order. 
         [0208]    When a file name of an original image data set is “xxx.jpg” and characters indicating a parameter specifying a conversion to generate a white image data set is “white”, the new reference to the white image data set (IMG tag) is described like &lt;img src=“xxx.jpg?white”&gt;. 
         [0209]    Instead of using different file names for each of white image data sets referred to in the text data set  11 , one predetermined file name may be commonly used for all of the white image data sets referred to in the text data set  11 . 
         [0210]    In the next step, i.e. in step S 309 , the Web page distribution server  1  specifies the maximum data size indicated by the output conditions, and judges whether a total data size, that is a sum of a data size of the text data set  11  to be distributed and data sizes of image data sets  13  and white image data sets referred to by the text data set  11 , does not exceed the maximum data size. 
         [0211]    In step S 309 , when the total data size does not exceed the maximum data size, the Web page distribution server  1  proceeds to step S 304 . 
         [0212]    In step S 309 , when the total data size exceeds the maximum data size, the Web page distribution server  1  proceeds to step S 310  and checks whether all of the references to the image data sets  13  (IMG tags) in the text data set  11  have already been replaced with references to white image data sets. 
         [0213]    In step S 310 , when all of the references have already been replaced with the references to the white image data sets, the Web page distribution server  1  proceeds to step S 311 . 
         [0214]    In step S 310 , when some of the references have not been replaced with the references to the white image data sets yet, the Web page distribution server  1  returns to step S 308 , and replaces the next reference to image data set  13  (IMG tag) in the inverse order of display of images in the Web page with a new reference to white image data set. Then, the Web page distribution server  1  repeats step S 309  and the steps following step S 309 . 
         [0215]    In each step S 311 , the Web page distribution server  1  selects one reference to a white image data set (IMG tag) in the text data set  11  in the inverse order of displays of images in the Web page, and replaces the reference to the white image data set with a reference to a substitute text data set. Namely, each time when step S 311  is executed, the reference to the white image data set (IMG tag) in the text data set  11  is replaced with a reference to a substitute text data set one by one in the inverse order. 
         [0216]    Substitute text data sets are explained below. As explained above, references to image data set (IMG tag) is described in a text data set  11  in a Web page description language such as &lt;img src=“xxx.jpg”&gt;. In the Web page description language, a reference to image data set (IMG tag) may contain a substitute text data (ALT attribute) indicating explanations of the referred image data set. For example, when an image data set identified by a file name “xxx.jpg” indicates a photo of an office room, a reference to the image data set (IMG tag) may contain a text data set indicating, for example, “photo of office space” as a substitute text data set like &lt;img src=“xxx.jpg” alt=“photo of office space”&gt;. 
         [0217]    Accordingly, a conversion from a reference to an image data set (IMG tag) to a substitute text data set is actually a replacement of the reference to the image data set (IMG tag) such as &lt;img src=“xxx.jpg” alt=“photo of office space”&gt; with the text data set contained in the reference such as “photo of office space”. 
         [0218]    When the reference to an image data set (IMG tag) does not contain a substitute text data (ALT attribute), a default text data set indicating, for example, “image  1 ” may be used as the substitute text data set. 
         [0219]    In the next step, i.e. in step S 312 , the Web page distribution server  1  specifies the maximum data size indicated by the output conditions, and judges whether a total data size, that is a sum of a data size of the text data set  11  to be distributed, which contains substitute text data sets, and data sizes of image data sets  13  and white image data sets referred to by the text data set  11 , does not exceed the maximum data size. 
         [0220]    In step S 312 , when the total data size does not exceed the maximum data size, the Web page distribution server  1  proceeds to step S 304 . 
         [0221]    In step S 312 , when the total data size exceeds the maximum data size, the Web page distribution server  1  proceeds to step S 313  and checks whether all of the references to image data sets (IMG tags) in the text data set  11  have already been replaced with substitute text data sets. 
         [0222]    In step S 313 , when all of the references have already been replaced with the substitute text data sets, the Web page distribution server  1  exits the series of processes for converting the Web page data set  10 , since there is no way to further decrease the total data size. 
         [0223]    In step S 313 , when some of the references have not been replaced with the substitute text data sets yet, the Web page distribution server  1  returns to step S 311 , and replaces the next reference to image data set (IMG tag) in the inverse order of display of images in the Web page with a substitute text data set. Then, the Web page distribution server  1  repeats step S 312  and the steps following step S 312 . 
         [0224]    In step S 304 , the Web page distribution server  1  converts all of the image data sets  12  referred to by the text data set  11  to generates middle sized image data sets  14   a  to  14   c . Then, the Web page distribution server  1  proceeds to step S 305 . As explained above, for each of the image data sets  12 , middle sized image data sets  14   a  to  14   c  each of which has different image quality from one another. 
         [0225]    In step S 305 , the Web page distribution server  1  replaces the references to image data sets (IMG tags) contained in the text data set  11  with new references to small sized image data sets  13  and to white image data sets, and then replaces the substitute text data sets with references to middle sized image data sets  14   a  to  14   c . Each time when step S 305  is executed, the original references to image data sets (IMG tags) are replaces with new references to the middle sized image data sets  14   a  to  14   c  one by one in an order of displays of images and in an order of image qualities of the middle sized image data sets  14   a  to  14   c.    
         [0226]    More concretely, in step S 305  of the first turn, a reference to an image data set whose image is to be displayed first in the Web page is replaced with a reference to a middle sized image data set  14   a  that has better quality than a middle sized image data set  14   b , in step S 305  in the second turn, the reference to the middle sized image data set  14   a  whose image is to be displayed first in the Web page is replaced with a reference to a middle sized image data set  14   b  that has better quality than a middle sized image data set  14   c , and step S 305  may be repeated in the similar way as explained with regard to steps S 305  of the first turn and the second turn. 
         [0227]    When a reference to an image data set (IMG tag) is replaced with a new reference to one of middle sized data sets  14   a  to  14   c , if a file name of the original image data set  12  is “xxx.jpg” and a parameter specifying a conversion of an image data set to a middle sized image data set  14   a  with 80% quality of the original image data set  12  is “80”, the original reference to the image data set  12  (IMG tag) is replaced with a new reference like “&lt;img src=“xxx.jpg?80”&gt;. 
         [0228]    The above mentioned parameter is just an example of various kinds of parameters, and any other parameters may be used in references if they can specify contents of conversions. 
         [0229]    In the next step, i.e. in step S 306 , the Web page distribution server  1  specifies the maximum data size indicated by the output conditions, and judges whether a total data size, that is a sum of a data size of the text data set  11  to be distributed, which contains substitute text data sets, and of data sizes of middle sized image data sets  14   a  to  14   c , image data sets  13  and white image data sets, which are referred to by the text data set  11 , does not exceed the maximum data size. 
         [0230]    In step S 306 , when the total data size does not exceed the maximum data size, the Web page distribution server  1  returns to step S 305 , selects the next reference to image data set (IMG tag) in the orders of display of images in the Web page with a substitute text data set and of image qualities of the middle sized image data sets  14   a  to  14   c , and replace the selected reference with a new reference to one of middle sized image data set  14   a  to  14   c . Then, the Web page distribution server  1  repeats step S 306  and the steps following step S 306 . 
         [0231]    In step S 306 , when the total data size exceeds the maximum data size, the Web page distribution server  1  proceeds to step S 306 A, and adopts the last version of text data set  11  that was judged that the total data size does not exceed the maximum data size as text data set  11  to be sent to the mobile phone  2 . The adopted version of text data set  11  is arranged to contain references to image data sets (IMG tags) that indicate images displayed in the upper part of the Web page with the best image qualities under the condition of limitation of the total data size. Then, the Web page distribution server  1  exits the series of processes for converting the Web page data set  10 . 
         [0232]    In the embodiment explained above, the Web page distribution server  1  selects one of middle sized image data sets  14   a  to  14   c  as the image data set with the best image quality under the condition of limitation of the total data size, but the present invention should not be limited in this respect, and for example, the original image data set, i.e. image data set  12  may be selected instead of one of image data sets  14   a  to  14   c  if the total data size does not exceeds the maximum data size. 
         [0233]    The adopted version of text data set  11  is distributed to the mobile phone  2  from the Web page distribution server  1 . The Web browser function of mobile phone  2  interprets the text data set  11 , and transmits distribution requests for image data sets  12 , small sized image data sets  13 , middle sized image data sets  14  and/or white image data sets that are referred to by the text indicated by the text data set  11 , to Web page distribution servers  1   a ,  1   b, . . . .    
         [0234]    As explained above, in the references to image data sets (IMG tags) in the text data set  11  may contain parameters specifying sorts of conversions applied to the image data sets in their file names in the forms of combinations of file names of image data sets  12  as their original image data sets and the parameters. Accordingly, each of the distribution requests for image data sets may contain a file name of image data set  12  as an original image data set of the requested image data set and a parameter specifying a sort of conversion applied to the original image data set to generate the requested image data set. 
         [0235]      FIG. 4B  shows a flow of processes executed by the Web page distribution server  1  that received a distribution request for an image data set for distributing the requested image data set to the mobile phone  2 . 
         [0236]    The Web page distribution server  1  proceeds to step S 201 , and specifies a file name of image data set  12  and a parameter of image data conversion that are contained in the distribution request for the image data set. 
         [0237]    In the next step, i.e. in step S 202 , the Web page distribution server  1  judges whether a small sized image data set  13  or middle sized image data set  14   a  to  14   c  that is generated by applying a conversion specified by the parameter to the image data set  12  specified by the file name specified in step  201  is stored in the storing unit (not shown) of the Web page distribution server  1 . 
         [0238]    When the image data set is stored in the storing unit, the Web page distribution server  1  proceeds to step S 204 . 
         [0239]    When the image data set is not stored in the storing unit, the Web page distribution server  1  proceeds to step S 203 , and converts the image data set  12  to generate one of a small sized image data set  13  or one of middle sized image data sets  14   a  to  14   c  in accordance with the parameter. The Web page distribution server  1  stores the generated image data set in its storing unit (not shown). 
         [0240]    In the next step, i.e. in step S 204 , the Web page distribution server  1  distributes the generated image data set to the mobile phone  2 , and exit the series of processes for distributing the requested image data set to the mobile phone  2 . 
         [0241]    It should be noted that any one of Web page distribution servers  1   a ,  1   b , . . . , that receives a distribution request for an image data set can generate the requested image data set by executing required conversion and distribute the requested image data set to the mobile phone  2  since the distribution request contains a file name of an original image data set  12  and a parameter specifying a sort of conversion applied to the original image data set. 
         [0242]    As explained above, the present embodiment provides a Web page distribution system that distributes Web page data sets that meet output conditions required for each of device models of target terminal devices. 
         [0243]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page, by referring to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets. 
         [0244]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that avoids too much degradation of qualities of images in a Web page, as well as require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page, by referring to, in addition to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets, middle sized image data sets, that have better quality than small sized image data sets. 
         [0245]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that avoids too much degradation of qualities of images displayed in an upper part of Web page that are comparatively more important than those in the lower part, as well as require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page, by referring to, in addition to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets, middle sized image data sets, that have better quality than small sized image data sets, in an order of displays of the images under the limitation of total data size. 
         [0246]    The present embodiment also provides a Web page distribution system that distributes a large number of Web page data sets that meet output conditions required for each of device models of target terminal devices at a high speed by limiting number of conversions conducted in connection with one Web page data set. For example, if only five conversions of image data set are conducted at Web page distribution servers in connection with one Web page data set, total burden and time required to execute the conversions of image data sets does not increase too much. 
         [0247]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page even when maximum data sizes of the target terminal devices are quite small, by referring to, in addition to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets, white image data sets that have smaller data sizes than small sized image data sets. 
         [0248]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page even when maximum data sizes of the target terminal devices are really small, by referring to, in addition to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets, white image data sets that have smaller data sizes than small sized image data sets in an inverse order of displays of images in a Web page. Since images displayed in the lower part of the Web page are probably less important than images displayed in the upper part of the Web page, influence of omissions of some of the images in the Web page can be minimized. 
         [0249]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page even when maximum data sizes of the target terminal devices are really small, as well as avoid too much degradation of the Web pages shown in accordance with the Web page data sets, by referring to, in addition to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets, white image data sets that have smaller data sizes than small sized image data sets and substitute text data sets that have smaller data sizes than white image data sets. 
         [0250]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that require total data sizes not exceeding the maximum data sizes of target terminal devices to display a Web page even when maximum data sizes of the target terminal devices are really small, by referring to, in addition to small sized image data sets that are converted from original image data sets so that their data sizes become smaller than those of their original image data sets and white image data sets that have smaller data sizes than small sized image data sets, substitute text data sets that have smaller data sizes than white image data sets in an inverse order of displays of images in a Web page. Since images displayed in the lower part of the Web page are probably less important than images displayed in the upper part of the Web page, influence of omissions of some of the images in the Web page can be minimized. 
         [0251]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that instruct to display images with display sizes that do not exceed the maximum display sizes of target terminal devices with minimum changes in layouts of Web pages, by converting image data sets so that their display sizes become equal or less than the maximum display sizes only when they exceed the maximum display sizes. 
         [0252]    The present embodiment also provides a Web page distribution system that distributes Web page data sets that require total data sizes not exceeding the maximum data sizes of target terminal devices even when a load balancing server is introduced to the system without requiring complex changes in the system since distribution requests for image data sets contain parameters used for converting original image data sets. Namely, even when a load balancing server is introduced to the Web page distribution system and a Web page distribution server handling a distribution request for a text data set and a Web page distribution server handling a distribution request for an image data set are different, the later Web page distribution server can determine, by the parameter, how to convert the original image data set to generate an image data set to be distributed to the terminal device sending the distribution request for the image data set. Therefore, there is no need for the plural Web page distribution servers to share converted image data sets. 
         [0253]    In a normal Web page distribution system, a relay server conducts conversions of image data sets and text data sets referring to the image data sets so that they meet output conditions required for each of terminal devices. When a load distribution function is installed to such a system, many complicated changes need to be made in both of the Web page distribution servers and the relay server. However, in a Web page distribution system in accordance with the present invention, no such a complicated change is required to realize the load distribution. 
         [0254]    In the present embodiment, once an image data set is converted to generate a converted image data set in a Web page distribution server, the converted image data set is stored in the Web page distribution server and reused when the same image data is to be distributed. Accordingly, a Web page distribution system that realizes speedy distributions of Web page data sets that meet output conditions required for each of device models of terminal devices, by saving load and time for converting the same original image data sets to generate the same converted image data sets. 
         [0255]    Especially, conversions from original image data set to small sized image data sets or middle sized image data sets require a heavy load of data processing and take a long time. Since the Web page distribution system is required to distribute a large number of image data sets quickly, the above mentioned save of load and time may bring a remarkable efficiency to the system. 
         [0256]    In the present embodiment, a text data set is converted so that it indicates a text described in a Web page description language that can be interpreted by a target device, by simply substituting original character strings with their substitute character strings in accordance with a substitute table showing correspondences between character strings used in two different Web page description languages. Since no grammatical analysis is required to execute the conversion of text data set in the present embodiment, when some minor grammatical changes are made to a Web page description language, only updates of the substitute tables are required. 
         [0257]    In the present embodiment, a Web page distribution system in accordance with the present invention is realized by installing an add-in module to a general program for a Web page distribution server. Accordingly, a Web page distribution system distributing Web page data sets that meet output conditions required for each of device models of terminal devices can be realized without introducing a new device such as a relay server to an existing Web page distribution system. Moreover, when a load distribution function is installed to the Web page distribution system, since the add-in module can achieve necessary changes in Web page distribution servers, it is only required to install the add-in module to each of the existing Web page distribution servers to realize the Web page distribution system in accordance with the present invention. 
         [0258]    In the above part, an exemplary embodiment of the present invention is explained with references to figures, and the present invention should not be limited to the embodiment. Namely, various modifications may be made in the above explained embodiment within the scope of the present invention. 
         [0259]    For example, the Web page distribution system is comprised of plural Web page distribution servers  1   a ,  1   b , . . . , and a load balancing server  4  in the above explained embodiment, but the present invention should not be limited in this respect and, for example, the Web page distribution system may be comprised of only one Web page distribution server. In the case, the Web page distribution server is directly connected to Internet  3 . Even when only one Web page distribution server is provided in the Web page distribution system, the system can distributes Web page data sets that meet output conditions required for each of terminal devices. 
         [0260]    In the above explained embodiment, image data sets  12  are not converted or converted to small sized image data sets  13 , middle sized image data sets  14   a  to  14   c , white image data sets or substitute text data sets, in accordance with output conditions regarding total data sizes required to display Web pages. The present invention should not be limited in this respect, and for example, image data sets  12  are not converted or converted to only small sized image data sets  13 . Namely, any of small sized image data sets, middle sized image data sets, white image data sets and substitute text data sets may be selectively used in the system. 
         [0261]    In the above explained embodiment, first image data sets  12  may be converted to small sized image data sets  13 , middle sized image data sets  14   a  to  14   c , white image data sets or substitute text data sets, in accordance with output conditions regarding total data sizes required to display Web pages, then the converted image data sets/substitute text data sets may be further converted to middle sized image data sets  14   a  to  14   c  in the order of displays in the Web page under the condition of limitation of total data size. The present invention should not be limited in this respect, and the converted image data sets/substitute text data sets may be further converted to middle sized image data sets in any other order. 
         [0262]    In the above explained embodiment, first image data sets  12  may be converted to small sized image data sets  13  in accordance with output conditions regarding total data sizes required to display Web pages, then the small sized image data sets  13  may be further converted to white image data sets or substitute text data sets in the inverse order of displays in the Web page to meet the output conditions. The present invention should not be limited in this respect, and the small sized image data sets may be further converted to white image data sets or substitute text data sets in any other order. 
         [0263]    In the above explained embodiment, display sizes of image data sets  12  may be converted in accordance with output conditions regarding maximum display sizes. The present invention should not be limited in this respect, and the conversions of display sizes of images may not necessarily conducted. For example, instead of converting display sizes of image data sets, indications of display sizes in IMG tags may be changed to indicate display sizes equal to or smaller than the maximum display sizes. 
         [0264]    In the above explained embodiment, small sized image data sets  13  and middle sized image data sets  14   a  to  14   c  are stored in a Web page distribution server that generated the image data sets, and reused when the converted image data sets are requested. The present invention should not be limited in this respect, and the Web page distribution server may repeat the conversions each time when the converted image data sets are requested. 
         [0265]    In the above explained embodiment, a text data set  11  refers to image data sets. The present invention should not be limited in this respect, and a text data set  11  may refer to any other sorts of data sets indicating components of Web pages, such as data sets for application programs executed in mobile phones  2 . 
         [0266]    In the above explained embodiment, both of text data conversion module  101  and image data conversion module  102  are installed to each of Web page distribution servers  1 . The present invention should not be limited in this respect, and for example, text data conversion module  101  is installed to a first Web page distribution server and image data conversion module  102  is installed to a second Web page distribution server, and the first and second Web page distribution servers may cooperatively conduct the conversions in the system. In the case, load balancing server  4  may distribute distribution requests for text data sets  11  to the first Web page distribution server to which text data conversion module  101  is installed, and distribute distribution requests for image data sets  12  to the second Web page distribution server to which image data conversion module  102  is installed. 
         [0000]    Since text data conversion module  101  and image data conversion module  102  may be separately installed to Web page distribution servers, when a large number of image data sets are distributed in a Web page distribution system such as a large scale e-commerce Web site, a provider of the Web site has to buy a small number of text data conversion modules  101  and a large number of image data conversion modules  102 , and install each of them to each of the existing Web page distribution servers. 
         [0267]    In the above explained embodiment, mobile phones  2  are the terminal devices each of which may have different output conditions to display Web pages. The present invention should not be limited in this respect, and any other sorts of terminal devices with output conditions such as maximum data sizes to be handled, such as mobile terminal devices other than mobile phones and computers executing programs with maximum data sizes to be handled (browsers displaying movies, etc.), may be used as terminal devices in the Web page distribution system in accordance with the present invention.