Abstract:
A method and article of manufacture of making dynamic content more accessible to screen readers and web spiders. The method applies to a server connected to a client via a network. The method includes receiving from the client an action event indicative of an action performed by a user on content displayed on the client and a change event indicative of a change in the content. The method further includes generating metadata for improving accessibility to the content based on the action event and the change event.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a U.S. National Stage application under 35 U.S.C. §317 based on International Application No. PCT/JP2010/055732, filed Mar. 30, 2010, published under PCT Article 21 (2) on Oct. 7, 2010 as WO/2010/113962, which claims priority from Japanese Patent Application No. 2011-507225 filed Mar. 30, 2010 which in turn claims priority from Japanese Patent Application No. 2009-091450 filed Apr. 3, 2009. The entire contents of all the above applications are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a technique for improving accessibility to web content and is directed to dynamic web content in particular. 
     BACKGROUND OF THE INVENTION 
     In the World Wide Web, there has been a gradual shift from static to dynamic content. Dynamic web content is created by using such techniques as DHTML, AJAX, and Flash, for instance. Such dynamic content enables web applications to provide users with experience of richer interaction and response. 
     NON-PATENT DOCUMENT 1 
     
         
         Miyashita, H., et al., Ai browser for multimedia: introducing multimedia content accessibility for visually impaired users, in Proceedings of the 9th international ACM SIGACCESS conference on Computers and accessibility. 2007, ACM: Tempe, Ariz., USA 
       
    
     NON-PATENT DOCUMENT 2 
     
         
         Frey, Gianni; Indexing AJAX Web Applications; ETH Department of Computer Science, Institute of Computational Sciences (2007). Available from: http://e-collection.ethbib.ethz.ch/view/eth:30111 
       
    
     NON-PATENT DOCUMENT 3 
     
         
         Ali Mesbah, Engin Bozdag, and Arie van Deursen., Crawling AJAX by Inferring User Interface State Changes. 2008, ICWE, Yorktown Heights, N.Y., USA Miyashita, H., et al., Ai browser for multimedia: introducing multimedia content accessibility for visually impaired users, in Proceedings of the 9th international ACM SIGACCESS conference on Computers and accessibility. 2007, ACM: Tempe, Ariz., USA. 
       
    
     NON-PATENT DOCUMENT 4 
     
         
         Borodin, Y., Bigham, J. P., Raman, R., Ramakrishnan, I. V., What&#39;s New?—Making Web Page Updates Accessible. To appear in Proceedings of the 10th international ACM SIGACCESS conference on Computers and accessibility. 2008, ACM: Nova Scotia, Canada 
       
    
     NON-PATENT DOCUMENT 5 
     
         
         Kawanaka, S., Borodin Y., Bigham, J., Lunn, D., Takagi, Hironobu, Asakawa, C., Accessibility Commons: A Metadata Infrastructure for Web Accessibility; to appear in the proceedings of ASSETS, 2008; Halifax, Canada. 
       
    
     NON-PATENT DOCUMENT 6 
     
         
         Takagi, H., S. Kawanaka, and M. Kobayashi. Social Accessibility: Achieving Accessibility through Collaborative Metadata Authoring; to appear in the proceedings of ASSETS, 2008; Halifax, Canada. 
       
    
     Rich web applications, however, have such a disadvantage as follows. Dynamic content is not fully accessible firstly to users who recognize web content aurally using a screen reader (e.g., visually-impaired persons) and secondly to web spiders (used by web search engines) that crawl the Web and create indices for web content. In the conventional static Web, individual web pages are reachable via static links, so screen readers and web spiders can exercise their capabilities by identifying static links in HTML source code. The state of a Rich Internet Application or RIA, however, is implicit, is determined by user action and changes according to user action. Such content cannot be fully accessed by screen readers or web spiders. 
     The present invention has been made in view of this disadvantage, and an object thereof is to provide a technique for making dynamic content more accessible to screen readers and web spiders. Other techniques and references pertaining to similar objects are listed above as Non-Patent Documents. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention can be any one of a method for application to a client, a method for application to a server, and a method for application to a client-server system. In a first aspect, the invention provides a method for application to a client connected with a server via a network, the method including the steps of tracking an action event indicative of an action performed by a user on content displayed on the client and a change event indicative of a change in the content, and generating metadata for improving accessibility to the content based on the action event and the change event. In a second aspect, the invention provides a method for application to a server connected with a client via a network, the method including the steps of receiving from the client an action event indicative of an action performed by a user on content displayed on the client and a change event indicative of a change in the content, and generating metadata for improving accessibility to the content based on the action event and the change event. In a third aspect, the invention provides a method for application to a client-server system in which a client and a server are connected with each other via a network, the method including the steps of tracking, on the client, an action event indicative of an action performed by a user on content displayed on the client and a change event indicative of a change in the content, receiving the action event and the change event from the client on the server, and generating, on the server, metadata for improving accessibility to the content based on the action event and the change event. 
     According to further aspects of the invention, the steps of transmitting the metadata from the client to the server and receiving the metadata from the server in response to the client requesting a web server to transmit the content may be further included. The client may further include a display device, a pointing device, and a communication device, and the steps of displaying content transmitted from the web server via the network on the display device through the communication device and operating on the content displayed on the display device in response to the user manipulating the pointing device may be further included. The metadata can improve accessibility to the content for a screen reader or a web spider. 
     The change event may occur in response to the action event or independently of the action event. 
     In yet another aspect of the invention, the step of generating the metadata may generate metadata that indicates relationship between the action event and the change event, metadata that indicates a type of the content, or both of them. 
     In a further aspect of the invention, the step of generating the metadata may generate the metadata based on a sequence of the action event and the change event, in which case the metadata may be generated based on a sequence that has occurred more or most frequently among multiple sequences. 
     Specifically, the action performed by the user on the content may be placing a pointer on the content, and the change in the content may be that new content is displayed in addition to the content. The content may be an element of a hierarchical menu, and the new content may be a submenu included in the element. The action performed by the user on the content may be clicking on the content, the change in the content may be a change in an attribute of the content, and the step of generating the metadata may generate metadata which indicates that the content is a checkbox provided that the clicking and the change in the attribute have been repeated multiple times. 
     Information identifying the content as a target may be included in the metadata. The information identifying the content may include a wildcard URL and/or a wildcard Xpath. 
     In another aspect of the invention, an article of manufacture tangibly embodying computer readable instructions which, when implemented, cause a server, a client or a client-server system, to carry out the aforementioned steps. The article of manufacture tangibly embodying computer readable instructions executable by a client may be provided in the form of a plug-in for a web browser, for example. The invention can also be perceived as a client, a server, or a client-server system that performs the aforementioned steps. 
     According to an aspect of the invention, a technique for making dynamic content more accessible to screen readers and web spiders can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing an overall structure of a system according to an embodiment of the invention; 
         FIG. 2  is a block diagram illustrating a typical hardware configuration of a computer system; 
         FIG. 3  is a block diagram illustrating a software configuration of a client computer; 
         FIG. 4  is a timing chart showing an overall flow of metadata generation and registration; 
         FIG. 5  shows how a user manipulates a dynamic menu as an illustration of metadata generation; 
         FIG. 6  shows how a user manipulates a checkbox as an illustration of metadata generation; 
         FIG. 7  shows events tracked by a tracer and metadata generated by an analyzer; 
         FIG. 8  is a timing chart showing an overall flow of metadata utilization; and 
         FIG. 9  illustrates the order of reading aloud a dynamic menu by a screen reader as an example of metadata utilization. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic diagram showing an overall configuration of a system, in which multiple computer systems are interconnected such that the systems can communicate with each other via the Internet (a network). The computer systems are classified into general client computers (clients)  1 A( 1 ) to  1 A(m), an accessibility server (a separate computer)  1 B, a web server (a server)  1 C, screen-reader client computers  1 D( 1 ) to  1 D(n), and a search server  1 E. 
       FIG. 2  is a block diagram illustrating a typical hardware configuration of a computer system. The computer system includes a (low- and high-speed) bus  40 , a Central Processing Unit (CPU)  41  connected to the bus, Random Access Memory (RAM)  42 , Read-Only Memory (ROM)  43 , a Hard Disk Drive (HDD)  44 , a communication interface (a communication device)  45 , and an input/output interface  46 . The computer system also includes a mouse (a pointing device)  47 , a CRT display (a display device)  48 , and a keyboard  49 , which are connected to the input/output interface  46 . While the computer system is described as adopting a personal computer architecture, the servers  1 B,  1 C and  1 E may have the CPU  41  and/or HDD  44  multiplexed for higher data processing capability and usability, for example. The functions of each of the servers  1 B,  1 C and  1 E may be realized by more than one computer system. For the general client computers (clients)  1 A( 1 ) to  1 A(m) and the screen-reader client computers  1 D( 1 ) to  1 D(n), various types of computer system, such as Personal Digital Assistant (PDA) and smartphone, may be adopted. 
       FIGS. 3(   a ) and  3 ( b ) are block diagrams illustrating software configurations of the general client computers (clients)  1 A( 1 ) to  1 A(m) and the screen-reader client computers  1 D( 1 ) to  1 D(n), respectively. Both types of client computers have an operating system (OS) to provide basic functions and a web browser as application software that utilizes the OS functions. By way of example, if both types of client computers are notebook or desktop personal computers, they include an operating system like Microsoft Windows® (a trademark) and a web browser such as Internet Explorer (a trademark) and Firefox (a trademark). On the general client computers (clients)  1 A( 1 ) to  1 A(m), plug-in software  3  for the web browser is installed. The plug-in software  3  includes a tracer  31  and an analyzer  32 . The functions of the analyzer  32  may alternatively be provided by the accessibility server (a separate computer)  1 B. Plug-in software  5  for the web browser is installed also on the screen-reader client computers  1 D( 1 ) to  1 D(n). The plug-in software  5  includes a transcoder  51 . The screen-reader client computers  1 D( 1 ) to  1 D(n) also have a screen reader as application software. 
     Based on the hardware and software configurations, client computer functions described below are realized: the software applications are loaded into the RAM  42  and executed by the CPU  41 . 
       FIGS. 4 to 7  illustrate generation and registration of metadata.  FIG. 4  is a timing chart showing an overall flow of metadata generation and registration;  FIG. 5  shows how a user manipulates a dynamic menu (positioning a pointer on a menu item causes display of a submenu) as an illustration of metadata generation;  FIG. 6  shows how a user manipulates a checkbox (clicking on the checkbox checks/unchecks the box) as an illustration of metadata generation; and  FIG. 7  shows events tracked by the tracer  31  and metadata generated by the analyzer  32 . 
     Referring to  FIG. 4 , a general client computer  1 A(i) among the general client computers (clients)  1 A( 1 ) to  1 A(m) sends a request to the web server  1 C via the Internet  2  (arrow s 1 ), and receives a web page transmitted by the web server  1 C in response to the request (arrow s 2 ). The web page contains multiple pieces of dynamic content. When the user performs some action on the web page, metadata is automatically generated without the user being aware of it and without requiring special operations or techniques (arrow s 3 ). How metadata can be generated is described in detail below. 
       FIG. 5  shows a case where a dynamic menu is included in a web page. When the user places a pointer on the item “Books” (the item in box A) in the menu, items of the level below it, “Books”, “Kindle”, “Textbooks”, and “Magazines &amp; Newspapers” (items in box B), appear. In parallel with it, the tracer  31  receives and stores events Ei and Ei+1 from the operating system or the browser. As shown in  FIG. 7 , EventName, Time, URL, and Xpath are stored for each event. For example, as event Ei that corresponds to movement of the pointer by the user, EventName “mousemove”, Time “ti”, a URL “(omitted)”, and Xpath “(a path indicating the portion A)” are stored. For event Ei+1 that corresponds to display of the lower-level items, EventName “DOMAttrModified”, Time “ti+1”, URL “(omitted)”, and Xpath “(a path indicating portion B”) are stored. Thus, each time the user performs an action or there is a change in content, events are tracked and stored by the tracer  31 . 
     Referring to  FIG. 7 , at certain time intervals, the analyzer  32  analyzes a sequence of such events and generates metadata. By way of example, if the time ti at which event Ei associated with the user&#39;s action occurred is compared with the time ti+1 at which the subsequent event Ei+1 occurred to find that their difference is smaller than a threshold, c, the analyzer  32  determines that event Ei+1 was caused by event Ei and generates metadata indicating it. If the difference between ti and ti+1 is equal to the threshold ε or greater, the analyzer  32  does not generate metadata. In this example, the difference is smaller than the threshold ε and metadata Mm is generated. For each metadata, a URL, Xpath 1 , Xpath 2 , type, and description are stored as shown in  FIG. 7 . By way of example, for metadata Mm which indicates that menu items of the lower level, “Books”, “Kindle”, “Textbooks”, and “Magazines &amp; Newspapers” (items in box B), appear when a user positions the pointer on the “Books” item (the item in box A), a URL “(omitted)”, Xpath 1  “(a path indicating portion A)”, Xpath 2  “(a path indicating portion B”), type “relation”, and description “weight=1” are stored. Type “relation” means that the portions A and B of the web page have a relationship of “A controlling B”, and description “weight=1” indicates that the metadata has been detected once. 
       FIG. 6  shows a case where checkboxes are included in a web page. When the user clicks on a checkbox (the portion in box C), the checkbox is unchecked and when the user clicks again, the checkbox is checked again. In parallel with it, the tracer  31  receives and stores events Ej, Ej+1, Ek, Ek+1, Ek, and Ek+1 from the operating system or browser. For each event, EventName, Time, URL, and Xpath are stored as in the aforementioned case. For example, for events Ej, Ek, and El that correspond to the user&#39;s clicks on the checkbox, EventName “click”, Time “tj”, “tk”, “tl” respectively, a URL “(omitted)”, and a Xpath “(a path indicating portion C)” are stored. For events Ej+1, Ek+1, and El+1 that correspond to checking and unchecking of the checkbox, EventName “DOMAttrModified”, Time “tj+1”, “tk+1”, “tl+1” respectively, URL “(omitted)”, and Xpath “(a path indicating portion C)” are stored. Thus, each time the user performs an action or there is a change in content, events are tracked and stored by the tracer  31 . 
     At certain time intervals, the analyzer  32  analyzes a sequence of these events and generates metadata. For example, if the time tj at which event Ei associated with the user&#39;s action occurred is compared with the time tj+1 at which the subsequent event Ei+1 occurred to find that their difference is smaller than a threshold c, the analyzer  32  determines that event Ej+1 was caused by event Ej. The analyzer  32  similarly identifies that event Ek+1 was caused by event Ek and event El+1 was by event El. When such determination has been made at least a predetermined number of times (e.g., three times), the analyzer  32  generates metadata Mn indicating that the portion surrounded by box C is a checkbox. For metadata Mn indicating that the portion in box C is a checkbox, a URL “(omitted)”, Xpath 1  “(a path indicating portion C)”, Xpath  2  “null”, type “role”, and description “checkbox” are stored. Type “role” indicates the role of portion C in the web page, and description “checkbox” means that the role is a checkbox. 
     The threshold value ε may be set as appropriate, e.g., to around 0.3 seconds. The threshold value ε may also be varied according to event E. For example, if an event requiring communication has occurred after event E associated with the user&#39;s action, the threshold value ε can be set to be longer (e.g., several seconds) than when such an event does not occur. If multiple event sequences (an event sequence is an event associated with the user&#39;s action and an event or events that occur within a certain time period after that event) are inconsistent with each other in terms of contents when metadata M is generated, an event sequence to be adopted may be determined by majority rule. Further, the URL and Xpath in metadata may be a wildcard URL and a wild Xpath (in which a part of the URL and path is represented by an arbitrary character string which is expressed as “*”, for example). Such a configuration enables representation of metadata that can be applied page- or site-wide. 
     Tracking of events can be started and ended by the plug-in software  3  according to explicit indications from the user, for example. After event tracking ends, the client sends generated metadata M to the accessibility server  1 D (arrow s 4  in  FIG. 4 ). The accessibility server  1 D stores the metadata M in a database such that the metadata M can be transmitted in response to an external request. Although herein the client computer  1 A(i) among the general client computers  1 A( 1 ) to  1 A(m) generates metadata and sends it to the accessibility server  1 D, this applies to the other general client computers  1 A( 1 ) to  1 A(m) as well. In addition, while general client computers  1 A( 1 ) to  1 A(m) generate metadata M in the description above, general client computers  1 A( 1 ) to  1 A(m) may send the event E to the accessibility server  1 B and the server  1 B may generate metadata M from the event E. 
       FIGS. 8 and 9  illustrate how metadata can be utilized.  FIG. 8  is a timing chart showing an overall flow of metadata utilization, and  FIG. 9  illustrates the order of reading aloud a dynamic menu (positioning of a pointer on a menu item causes display of a submenu) by a screen reader as an example of metadata utilization. 
     Referring to  FIG. 8 , a screen-reader client  1 D(j) among screen-reader clients  1 D( 1 ) to  1 D(n) sends a request to the web server  1 C via the Internet  2  (arrow s 11 ) and receives a web page transmitted by the web server  1 C in response to the request (arrow s 12 ). The screen-reader client  1 D(j) also sends a request to the accessibility server  1 B via the Internet  2  (arrow s 11 ′). In response to the request, the accessibility server  1 B sends metadata M corresponding to the web page and the client  1 D(j) receives the metadata M (arrow s 12 ′). The transcoder  51  of the client  1 D(j) can use the metadata M to provide a user of the screen reader (e.g., a visually-impaired person) with a more accessible environment (arrow s 13 ). 
       FIG. 9  illustrates reading aloud of a dynamic menu included in a web page using metadata Mn on the client D(j). For example, if the transcoder  51  is incorporated in the screen reader, the transcoder  51  can use metadata Mm to determine that in stead of “Movies, Music and Games”, items positioned in the level under the “Books” item, i.e., “Books”, “Kindle”, “Textbooks”, and “Magazines &amp; Newspapers” (the items in box B) should be read after “Books” (the item in box A). This order of reading reflects the way of many general users browsing the Web. If the transcoder  51  is independent from the screen reader, the transcoder  51  still can direct the screen reader where to read next. Similarly, when reading a checkbox, a screen reader can explicitly tell that it is a checkbox by use of metadata Mn. 
     Metadata M can be used to realize correct order and contents of reading by a screen reader and also allow a web spider of the search server  1 E to appropriately crawl web page contents and create indices for them. For example, for web content that should be newly downloaded from the web server  1 C in response to an action by the user, information on the content can be appropriately acquired based on “relation” information in the corresponding metadata.