Abstract:
The present invention is directed to method and apparatus that enables a web-based client-server application to be used offline that substantially obviate one or more problems due to limitations and disadvantages of the related art. According to one aspect of the present invention, a method for using a web-based client-server application offline, the method comprise: reading a markup file including a list of web resource file and period information; connecting periodically to web server according to the period information; downloading the web resource file included in the markup file form the web server to a cache included in the application.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 61/553,231 filed on, Oct. 30, 2011 which is hereby incorporated by reference as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to web browsers. More specifically, the present invention relates to a method and an apparatus that enables a web-based client-server application to be used offline. 
     2. Discussion of the Related Art 
     Scripting languages and dynamic components are often used in web pages to provide complex functionality to a user. Web servers process many of these scripts and components, and send the resulting output HyperText Markup Language (HTML) code to a browser for display to the user. However, this type of client-server web application requires a connection to the web server to be able to use the client-server web application. 
     In order to facilitate offline browsing, browsers typically provide a caching mechanism which enables every web page that is delivered to the browser to be stored in a browser cache. At some subsequent time, if the user attempts to view a previously viewed page and the client does not have a connection to the web server that hosted the web page, the browser can retrieve a copy of the web page from the browser cache and can display the copy of the web page to the user. 
     Modern web applications deliver display logic and data to the browser, such as JavaScript with HTML. Sometime this data has been preformatted for display purpose and sometimes the data is very raw. In either case, the files that are cached are only a snapshot of the data at one point in time, and may be irrelevant to the user at a subsequent time. Moreover, in many instances, the web application prevents this data from being cached. 
     Consider the example of a browser-based email application. If the browser cache only contains a static representation of the web page from the last time the user visited the browser-based email site, then the web page retrieved from the cache will not be very useful to the user. If the user is only presented with static representations of what was previously viewed, and the server-side logic is not being executed, then the user&#39;s actions on the cached pages do not result in the actions intended by the user. Moreover, this can lead to confusion because the user might believe that he or she performed some action that was actually not performed because the server-side logic was not executed. 
     Hence, what is needed is a method and an apparatus for viewing dynamic web pages in a browser without the problems listed above. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to method and apparatus that enables a web-based client-server application to be used offline that substantially obviate one or more problems due to limitations and disadvantages of the related art. 
     According to one aspect of the present invention, a method for using a web-based client-server application offline, the method comprise: reading a markup file including a list of web resource file and period information; connecting periodically to web server according to the period information; downloading the web resource file included in the markup file form the web server to a cache included in the application. 
     The method further comprises: checking periodically whether the web resource file is updated in the web server; and downloading the updated web resource file included in the markup file form the web server to the cache. 
     The method further comprises: presenting a web page using the downloaded web resource file on offline status. 
     The period information is specified in a manifest file included in the markup file. 
     The period information is set up by at least one of an author of the application and a user of the application and the application. 
     The period information is set up by considering to at least one of a web server&#39;s priority, and a specified period, and number of visits (frequency of use), and a recently visited site. 
     The period information is set up by considering to at least one of a visit history, and a update frequency of the web resource, and the current network usage. 
     The period information is set up by considering to at least one of a network situation (3G/Wifi/wired/roaming/etc.), and whether the amount remaining in the current plan data, and a current time (day or night). 
     According to another aspect of the present invention, a computer-readable storage medium storing instructions that when executed by a computer cause the computer to perform a method for using a web-based client-server application offline, the method comprising: reading a markup file including a list of web resource file and period information; connecting periodically to web server according to the period information; downloading the web resource file included in the markup file form the web server to a cache included in the application. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  illustrates a computing environment in accordance with an embodiment of the present invention. 
         FIG. 2  illustrates a browser in accordance with an embodiment of the present invention. 
         FIG. 3A  illustrates an AJAX function in accordance with an embodiment of the present invention. 
         FIG. 3B  illustrates a proxy AJAX function in accordance with an embodiment of the present invention. 
         FIG. 4  presents a flow chart illustrating the process of redirecting a function call in accordance with an embodiment of the present invention. 
         FIG. 5  illustrates a markup file for storing web resource in accordance with the other embodiment of the present invention. 
         FIG. 6  illustrates a browser in accordance with the other embodiment of the present invention. 
         FIG. 7  illustrates a markup file including period information in accordance with the other embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims. 
     The data structures and code described in this detailed description are typically stored on a computer-readable storage medium, which may be any device or medium that can store code and/or data for use by a computer system. This includes, but is not limited to, volatile memory, non-volatile memory, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs), DVDs (digital versatile discs or digital video discs), or other media capable of storing computer-readable media now known or later developed. 
     One embodiment of the present invention provides a system that facilitates using a web-based client-server application offline. During operation, the system receives a function call at an object within a browser which is executing on a client, wherein the function call is generated by the web-based client-server application and is directed to the browser&#39;s communication layer on the client. Next, the system determines an intended resource for the function call. The system also determines if the function call should be redirected to an alternate resource within the web-application. If so, the system redirects the function call to the alternate resource. If not, the system forwards the function call to the intended server-based resource. 
     In some embodiments of the present invention, the alternate resource replicates the actions of a server-based resource. In these embodiments, the alternate resource performs the functions of the server-based resource which makes it appear that the client is communicating with the server. While the alternate resource replicates the actions of the server, the alternate resource may or may not execute the same code as the server. In many embodiments, the alternate resource executes different code that performs similar functionality as the server. Note that the alternate resource may include client-side. 
     Asynchronous JavaScript and XML (AJAX) to replicate the functionality of the server-side components to present a similar view to a user as if the client was communicating with the server. 
     In some embodiments of the present invention, determining if the function call should be redirected to an alternate resource involves determining if the client is working in an offline mode. 
     In some embodiments of the present invention, determining if the function call should be redirected to an alternate resource involves determining if the intended resource is not reachable. 
     In some embodiments of the present invention, determining if the function call should be redirected to an alternate resource involves receiving a redirection command from the web-based client-server application. 
     In some embodiments of the present invention, the intended resource is located on a server and the alternate resource is located on the client. 
     In some embodiments of the present invention, the web-based client-server application is an Asynchronous JavaScript and XML (AJAX) application. 
     In some embodiments of the present invention, redirecting the function call involves redirecting the function call in a manner that is not visible to a user. 
     In some embodiments of the present invention, the object is part of the browser. 
     In some embodiments of the present invention, the object is a browser extension. 
     In some embodiments of the present invention, the object is external to the browser, and has hooks into a framework of the browser. 
       FIG. 1  illustrates a computing environment  100  in accordance with an embodiment of the present invention. Computing environment  100  includes a number of computer systems, which can generally include any type of computer system based on a microprocessor, a mainframe computer, a digital signal processor, a portable computing device, a personal organizer, a device controller, or a computational engine within an appliance. More specifically, referring to  FIG. 1 , computing environment  100  includes clients  110 - 112 , users  120  and  121 , servers  130 - 150 , network  160 , database  170 , and devices  180 . 
     Clients  110 - 112  can include any node on a network including computational capability and including a mechanism for communicating across the network. 
     Similarly, servers  130 - 150  can generally include any node on a network including a mechanism for servicing requests from a client for computational and/or data storage resources. 
     Users  120  and  121  can include: an individual; a group of individuals; an organization; a group of organizations; a computing system; a group of computing systems; or any other entity that can interact with computing environment  100 . 
     Network  160  can include any type of wired or wireless communication channel capable of coupling together computing nodes. This includes, but is not limited to, a local area network, a wide area network, or a combination of networks. In one embodiment of the present invention, network  160  includes the Internet. In some embodiments of the present invention, network  160  includes phone and cellular phone networks. 
     Database  170  can include any type of system for storing data in non-volatile storage. This includes, but is not limited to, systems based upon magnetic, optical, or magneto-optical storage devices, as well as storage devices based on flash memory and/or battery-backed up memory. Note that database  170  can be coupled: to a server (such as server  150 ), to a client, or directly to a network, such as network  160 . 
     Devices  180  can include any type of electronic device that can be coupled to a client, such as client  112 . This includes, but is not limited to, cell phones, Personal Digital Assistants (PDAs), smart-phones, personal music players (such as MP3 players), gaming systems, digital cameras, portable storage media, or any other device that can be coupled to the client. Note that in some embodiments of the present invention, devices  180  can be coupled directly to network  160  and can function in the same manner as clients  110 - 112 . 
     Browser  190  is installed on client  110 . In one embodiment of the present invention, browser  190  can include any program that is capable of displaying web pages that include scripts. Note that browser  190  can be installed on any computational device, such as clients  110 - 112 , servers  130 - 150 , and devices  180 . 
       FIG. 2  illustrates a browser  190  in accordance with an embodiment of the present invention. Browser  190  includes: application logic  202 , redirection object  204 , server A communication layer  210 , server B communication layer  211 , and local server communication layer  212 . In a traditional web application, application logic  202  is coupled to server communication layer  210 , and communicates with server A via server A communication layer  210 . However, embodiments of the present invention include a redirection object  204  which may direct function calls: (1) to server A communication layer  210 , (2) to the communication layer associated with another remote server (such as server B communication layer  211 ), or (3) to a different resource (such as local server communication layer  212 ). Note that browser  190  can execute on any node including computational capability, including clients  110 - 112 , servers  130 - 150 , and devices  180 . 
     In some embodiments of the present invention, application logic  202  communicates with redirection object  204 , and redirection object  204  communicates with: server A communication layer  210 , server B communication layer  211 , and local server communication layer  212  via JavaScript™. While JavaScript™ is shown in these embodiments, in general any method for communicating between these components may be used. 
     Redirection object  204  intercepts function calls to the communications layer and redirects these calls based upon pre-determined criteria, such as: if the intended destination is unreachable, if the browser  190  is marked as offline, if directed by application logic  202 , or any other criteria. Redirection object  204  may redirect function calls to remote servers (servers  130 - 150 ), local servers executing on the same client  110 , as well as resources which are internal and/or external to client  110 , such as database  170 . 
     In some embodiments of the present invention, redirection object  204  directs the function calls to local server communication layer  212 . Local server communication layer  212  acts as a liaison between browser  190  and a local server executing on the same client  110  as browser  190 . Such a redirection may be beneficial in cases where client  110  is disconnected from network  160 , and thus has no connection to the intended resource. 
     Note that the local server executing on client  110  may include code that performs the same functionality as the server code, or alternatively, cached copies of the server code, including any server-side scripting, such as Java Server Pages (JSP) code and Active Server Pages (ASP) code. In this example, the local server processes the server-side code in lieu of the intended server. Furthermore, the end-result is transparent to the user  120 . 
     To user  120 , it appears no different than if redirection object  204  forwarded the function call to the intended server rather than to the local server. 
     In one embodiment of the present invention, a programmer identifies the functions and methods that call the server, and then creates proxies for those functions. Note that this is possible in JS because JS is a dynamic language that allows the redefinition of functions and methods at runtime. In this embodiment, the programmer redefines the function so that the function tests which server to use, and then calls the desired server implementation. 
       FIG. 3A  illustrates an Asynchronous JavaScript and XML (AJAX) function prior to modification in accordance with an embodiment of the present invention.  FIG. 3B  illustrates a proxy AJAX function in accordance with an embodiment of the present invention. In the example illustrated in  FIG. 3B , a programmer does not have to modify every single function, but instead, can centralize the communication layer to one single entry point. When writing the code for the application, the programmer can simply make each function call via the createProxy (f-type) function. Note that for embodiments of the present invention, a proxy function is defined as a function that is invoked in place of an existing function, and then determines whether to invoke the existing function, to invoke an alternate function, or to invoke the existing function with different arguments. This is in contrast to a “proxy” that stores content at the proxy and acts on behalf of existing servers by returning content from the proxy rather than from the servers when requests are made. 
       FIG. 4  presents a flow chart illustrating the process of redirecting a function call in accordance with an embodiment of the present invention. During operation, the system receives a function call at redirection object  204  (operation  402 ) and determines the intended resource for the function call (operation  404 ). Next, the system determines if the function call should be directed to an alternate resource (operation  406 ). Note that this redirection decision is based upon pre-determined criteria, such as: if the intended destination is unreachable, if the browser  190  is marked as offline, if directed by application logic  202 , or any other criteria. Redirection object  204  may redirect function calls to remote servers (servers  130 - 150 ), local servers executing on the same client  110 , as well as resources internal and/or external to client  110 , such as database  170 . 
     If the function call should be directed to an alternate resource, redirection object  204  redirects the function call to the alternate resource (operation  408 ). However, if not, redirection object  204  forwards the function call to the intended resource (operation  410 ). 
     In below, another embodiment of the present invention is described. Another embodiment of the present invention presents the method for user to use the web application same as online status, even if the application is not connected with web server (offline status). 
       FIG. 5  illustrates a markup file for storing web resource in accordance with the other embodiment of the present invention. 
     The markup file of  FIG. 5  provides the method how to operate same as online status, even if on offline status, using cache of web application. 
     As shown in drawings of “clock.html”, the markup file of the present invention specifies a manifest file that is used in the markup file, for example, it may be specified as “&lt;html manifest=” . . . “&gt;”. 
     As shown in the drawing, CACHE MANIFEST section, FALLBACK section, and NETWORK section are specified in the manifest file. 
     The CACHE MANIFEST section specifies the web resource files temporarily storing from web pages. 
     And, the FALLBACK section specifies web resource files, which are used instead when the web resource files stored temporarily, do not exist in the cache, and on offline. 
     And, the NETWORK section specifies the list of web resource files downloadable from the web page on the online status. 
     Therefore, web application uses web resource files needed to output web page and stored in the cache, if it is in the caches, using the aforementioned markup file. And, when web resource files are updated, web application downloads the web resource files that are specified in the CACHE MANIFEST section to the cache for future access, or offline if you are using. 
     However, some web resources stored in the cache of the web application (main image, for example, real-time data, etc.) can be updated frequently from the Web server. Thus, the problem is how to update the web resources even if the user does not connect directly to the web server using web applications. 
     In below, the method for updating web resource periodically is described. 
       FIG. 6  illustrates a browser in accordance with the other embodiment of the present invention. 
     The browser  180  of the present invention further includes application cache  310  and application cache manager  320 . 
     The application cache  310  is temporary data storage for storing web resource files downloaded from the web server by the browser  180 . 
     The application cache manager  320  connects to the web server, and checks for updates of the web resource, and downloads the updated web resource to application cache  310 , using markup file which will be described later 
     Therefore, application cache manager ( 320 ) periodically checks for updates of the web resource, and downloads the updated web resource to application cache  310  automatically, according to the period information specified in the markup file which will be described later. 
     However, the drawings illustrates the application cache manager  320  is included in the browser  180 , but this example, and the application cache manager  320  may be presented as separated the background service. 
       FIG. 7  illustrates a markup file including period information in accordance with the other embodiment of the present invention. 
     As shown in  FIG. 7 , the manifest file of the markup file further includes the PERIODICAL section  400 . 
     The period information is specified in the PERIODICAL section  400 . Therefore, the application cache manager ( 320 ) checks updated web resource in the corresponding period, downloads automatically the updated resource from the Web server to the application cache  310  according to the period information which is specified in the PERIODICAL section  400 . 
     That is, the time information when the application cache manager  320  checks and downloads the web resource is included in the period information of the PERIODIC section  400 . 
     The subject and the elements specified in PERIODIC section  400  can be set various settings as follows. 
     First of all, at least one of the author of the web application and the user of the web application and web application can determine the foregoing period information. 
     First of all, the author of the web application can record the period information explicitly, when the author of the web application creates the PERIODIC section  400  of the manifest file . . . . 
     And, the user of the web application can set up the period information for each Web application through the web application manager or general preference settings. 
     And, the web applications can set up to decide the period information automatically. 
     Finally, the combination of the aforementioned three subjects can also determine the period information. That is, period information can be set by the author of web application, the user of web application and web applications in order of priority. 
     And, the PERIODIC section ( 400 ) can be determined through the following elements. 
     That is, the periodic information can be set up considering to the Web server&#39;s priority, specified period, the number of visits (frequency of use), the recently visited site, the visit history, the update frequency of web resource, the current network usage, the network situation (3G/Wifi/wired/roaming/etc), whether the amount remaining in the current plan data, the current time (day or night) and etc. 
     Therefore, the author of the web application, the web application&#39;s user and web applications can be set up the periodic information based on the aforementioned factors. 
     The foregoing descriptions of embodiments of the present invention have been presented only for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention. The scope of the present invention is defined by the appended claims. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.