Abstract:
The present invention is a novel management system for selectively distributing applications and databases from a server computer to a plurality of intermittently connected handheld devices. The applications and databases to be downloaded and deleted are first selected from an application list maintained by handheld devices. After established a connection with the server computer, the application list of selected applications is copied to the server computer which maintains an access control list indicating which applications are permitted to be downloaded to which handheld devices. The server computer examines the application list and the access control list to determine which applications are both selected and are authorized for use by the handheld device. After determining that requested applications are authorized for requesting devices, these applications are downloaded. If the connected handheld device does not have that the application list, the application list is created for it and downloaded.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the management of the distribution of applications and databases between electronic devices and more specifically, to a novel management system for selectively distributing applications and databases from a computer to a plurality of intermittently connected handheld devices. 
     2. Description of Prior Art 
     With the rapid advancement of semiconductor, storage, and display technologies, handheld or mobile devices have become increasingly popular. The handheld devices, such as a Palm Pilot, a Windows CE, a Zaurus, a Psion, a smart phone, or an intelligent pager have become very versatile. A handheld device may be used as a Personal Digital Assistant (PDA) providing such functions as e-mail, address book, calendar. Internet freeware, such as games, may be downloaded to the handheld device for leisure use. Business related applications and databases may be installed to improve productivity. 
     In an organizational setting, such as a corporation, an important issue in managing handheld devices is the distribution control of the applications to be installed in the handheld devices. For example, a corporation may develop several different sets of automated work procedures for handheld devices: customer account management procedures for the sales department; machine operation procedures for factories; and inventory control procedures for warehouses. 
     It may be valuable that the sales department devices receive only the account management application, the factory devices receive only the machine operation applications, and the warehouse devices receive only the inventory control applications. It may also be useful that, based on employee roles, devices belonging to different employees receive different sets of applications, matched to the employees&#39; respective roles. A manager&#39;s device, for example, may get an employee evaluation tool which is not distributed to an employee&#39;s device. Furthermore, an organization may provide an additional set of applications, such as utility software, games, and other information databases. At the user&#39;s discretion, a subset of these applications may be chosen for download to each handheld device. 
     Handheld devices install applications through the synchronization process which is typically performed between the device and a PC. First, the application must be accessible by the PC which, through its serial port, is connected to the target handheld device. The PC software may be executed to load the target application into an “install” directory accessible by the synchronization manager software. The synchronization process is initiated by pushing a handheld device button, such as the HotSync button in Palm Pilot. Immediately after the button is pushed, synchronization manager software, such as the HotSync Manager used with Palm Pilot&#39;s, in the PC takes over the synchronization process during which the applications loaded in the “install” directory are downloaded and installed into the handheld device. 
     This software distribution process is a standalone system synchronizing software between a PC and a handheld device, it does not have centralized software distribution management functions. To distribute an application among many handheld devices, the application must first be copied to the PCS of all the target handheld device owners. After that, it is up to each owner to conduct the synchronization process to install this application from the PC in to the handheld device. Hence, there is no efficient way to determine which handheld devices have the target application installed. 
     An alternative way of distributing handheld applications within an organization, is to have a centralized server that manages a user pool, a handheld device pool, and an application pool. To install an application, a handheld device must first connect to the network and make such a request directly to the centralized server. It is the server&#39;s responsibility to authenticate the handheld device and its user, to authorize the application installation request based on the user profile, the device usage, and a pre-configured access-control policy. If the application installation request is authorized, the server downloads the target applications to the device. 
     The centralized server may update the application status of the handheld device, e.g., what applications have been installed in this device?, update the handheld device status associated with the target application that are managed by the centralized server, e.g., what devices have downloaded this application?, and log this download activity in the server&#39;s event logs. The event logs and the application status recorded by the server may provide important information in managing software distribution. 
     The traditional client-server model assumes a persistent network connection which exists for both the clients and the server. Therefore, the client requests and the corresponding services performed by the server are more interactive. Every time a client decides to examine the applications managed by the server that are available, the client may connect to the server, retrieve an updated list of available applications, choose the desired applications while the client is still connected to the server, and proceed to download the selected applications from the server. The client has no need to keep the list of applications and the status of these applications. The list of applications available to the client may be retrieved, and the status of each application on the client device determined during the interactive real-time query exchange between the client and the server. 
     The drawback of the traditional client-server model, however, is that the network connection of the handheld devices is not persistent. Only occasionally do handheld devices connect to the network, and typically the connection, through a low-bandwidth medium such as a modem or a serial cable, lasts a short time. It may be advantageous for each handheld client to maintain a list of applications that are available from the server. 
     Maintaining a list of applications may be accomplished in the following ways. The user of a handheld device may run software to perform application selection based on the application list while the device is not connected to the network. Therefore, no time-costly interactive application selection process occurs when the client is connected to the server. 
     Alternatively, while the device is disconnected, it may investigate and record the status of each application in the application list. This way, when the client is connected to the server, all information about the application status is already available. The server does not have to interactively query client for the status of each application, thereby further improves the efficiency of bandwidth and time usage when the client remains connected. 
     Many handheld devices have built-in support of a synchronization function which compares the two records with the same ID respectively from the device and a synchronization host and, based on an application dependent set of rules, determines if a record from one side override that of the other side or if other actions, such as replicate both records to the other side with a new ID should be taken. 
     The retrieval of the application list from the client by the server may directly use the synchronization function provided by these handheld devices. 
     SUMMARY OF THE INVENTION 
     In accordance with the aforementioned needs, the present invention is directed to a method and apparatus of a server-based handheld application management system. In this system, the server manages a pool of users, a pool of handheld devices, a pool of handheld applications, and a set of access-control policies governing which handheld devices owned by what users are authorized to download a subset of the applications. 
     In the present invention, the clients are handheld devices that are only occasionally connected to the server for distribution of applications. When they are connected, typically the connection lasts a short period of time and is through a low-bandwidth medium such as a modem or a serial line. The process of a client requesting for application download and the server servicing this request must be performed while the requesting clients remain connected to the network. 
     According to the present invention, an application list structure is provided to record the status of all applications available to a client, that are managed by the server. The status for an application may indicate if this application is installed in a client and if it is selected to be installed to this client next time this client connects to the server. 
     When a client connects to the server, a method is provided for the server to retrieve the application list from this client and to download a subset of applications in the list to the client, based on the status of each application in the list as well as the up-to-date access-control policy, and to update the application list in the client based on the up-to-date access-control policy. 
     Accordingly, the client updates its application list by allowing the user to select the applications to be downloaded the next time this client synchronizes with the server and by allowing the user to delete the applications that are installed in this client. This activity may be performed at any time, regardless whether the client is or is not connected to the network. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The foregoing objects and advantages of the present invention may be more readily understood by one skilled in the art with reference being had to the following detailed description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings wherein like elements are designated by identical reference numerals throughout the several views, and in which: 
     FIG. 1 is a diagram of the server based handheld application management system of the present invention; 
     FIG. 2 is a diagram of a handheld features of the present invention; 
     FIG. 3 is an example of an application list structure of the present invention; 
     FIG. 4 is a diagram of an architecture of a server feature of the present invention; 
     FIG. 5 is a flow diagram of the application list manager process of the present invention; 
     FIG. 6 is a flow diagram of the server logic of the present invention; 
     FIG. 7 is a flow diagram of the application distribution manager process of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows an example of an overall network architecture of the server based handheld application management system of the present invention. A client  101 ,  102 , which is a handheld device and a server  107 , which may be a PC, a workstation, a mainframe, or any other type of a device able to store and to upload information, are connected to the network  105  through connections  103 ,  104  and  106 . Although the server  107  may or may not be connected to the network  105  The clients  101 ,  102  are more likely to be disconnected from the network  105  most of the time. However, while their application download requests are serviced by the server clients  101 ,  102  must remain connected to the network  105 . 
     The process of a client requesting application download and the server servicing this request is performed while the requesting client remains connected to the network. A handheld device can obtain a connection to a network, such as the Internet or a local area network, by dialing up to a network remote access server through a modem, or by having a direct serial-port connection, e.g., the Palm Pilot cradle, to a network connected intermediary computer. In the former case, the client synchronizes with the server directly; in the latter case, the client synchronizes with the server through an intermediate computer which passes along the information transmitted back and forth between the client and the server. 
     FIG. 2 shows an example of an overall architecture of a handheld device capable of performing updates of the application list based on the method of the present invention. It includes a CPU  201 , main memory  204 , such as volatile RAM, and storage memory  202 , such as nonvolatile RAM, ROM or disk. In general, the main memory  204  stores programs to be executed and the storage memory  202  stores systems, e.g., operating systems, applications not currently being executed, as well as the data, such as the contents of the address book or memo pad applications. The distinction between the main memory  204  and the storage memory  202  may not exist for some handheld devices. Those devices may store all information in RAM and ROM without any disks and execute programs directly from where the programs are stored. 
     In the present invention, an application list structure  203  is stored in the storage memory  202 . The logic or the executable program code for updating and managing this application list  203  is the application list manager  205 . The synchronization client  206  is the client function used when a handheld device starts synchronization with a synchronization host. In the present invention, the synchronization host may be the server PC, workstation, mainframe, etc. 
     Many handheld devices have built-in support for a synchronization client, such as the HotSync Manager client in Palm Pilot. The main tasks of a synchronization client include: receiving a synchronization API request from the synchronization host, e.g., read, write, update, or insert a record; executing the corresponding system function within the device; receiving an application from the synchronization host; and installing it on the handheld device. The synchronization client is used in the present invention to synchronize the application list from the client to the server and to install applications from the server to the client. 
     FIG. 3 shows the structure of an application list  301 . 
     Each item in the list contains two sets of information, the application identification information  302 ,  304 ,  306  and the application status information  303 ,  305 ,  307 . The application identification information is used to identify the application. The application identification information may include application&#39;s ID, name, version, icon, etc. The application status information is used to record its up-to-date status. The application status information may include a flag indicating if this application is installed in the host handheld device, a flag indicating if this application is selected by the user to be distributed from the server at the next time the host device connects to the server, etc. 
     FIG. 4 shows architecture of a server PC, workstation, mainframe, etc., of the present invention, which includes a CPU  401 , main memory  402 , such as RAM, and storage devices  403 . The main memory  402  stores the server logic  409  of the present invention which is preferably embodied as computer executable code which may be loaded from storage devices  403  into the main memory  402 . The storage devices  403  store the user pool  404 , the application pool  405 , the device pool  406 , the access control list  407  for governing which user and which device may be allowed which application, and the log  408  to log the computer activities. 
     The user pool  404 , the application pool  405 , and the device pool  406  may be implemented as a tables in a relational database or other types of data structure in various information management systems, such as the Lotus Notes, which may provide storage for each type of information and its attributes. Such information management systems should preferably provide a retrieval and search functions. 
     Furthermore, to satisfy the aforementioned application management function in monitoring what applications have been installed in which devices, a preferred implementation of the server of the present invention may store and manage one application list for each device in the device pool that reflects the client application list in the corresponding device. The access control list  407  is a way to associate each application to a list of users and a list of devices that are authorized to download this application. An alternative implementation of the access control list, sometimes called the capability list, is to associate each user or device with a list of applications authorized for download for this user or device. 
     FIG. 5 shows the logic flow of the application list manager  205  (FIG. 2) in the client device, used to modify the application list  506 . After the application manager is started in step  501 , the list of applications  506  available for download from the server is displayed in step  502 . In step  503 , the user selects applications to either delete or to download. If the application was selected for deletion, at step  504  it is deleted from the client device if the application was installed there. If the application was selected for download, a request to download the next time the client synchronizes with the server is issued at step  505 . At step  506 , the status of all applications is updated accordingly and recorded in the application list  506 , after which the program control returns to step  502 . 
     FIG. 6 shows logic flow of the server  409  (FIG. 4) executed by the server of the present invention in servicing a client request for application distribution or download  505  (FIG.  5 ). The server waits for and accepts a client request at step  601 . If a client request is accepted, indicating that the client has successfully connected to the server, the server authenticates the client at step  602 . The server may deploy techniques such as the encrypted password approach or the share secret public key approach among others to authenticate the client. 
     When the client is authenticated, in step  603 , the server determines whether the client device has an application list. If the client has an application list, the server retrieves it in step  605 . Alternatively, if the application list does not exist on the client device, in step  604 , the server creates an application list of applications authorized to be distributed to a particular user and to a particular device based on the user ID, the device ID of the client and the access control list  607 . 
     In both situations processing continues in step  606  where the application distribution manager process is started. The application distribution manager process: 
     a. compares the client application list with the access control list  607 ; 
     b. performs appropriate updates to the client application list, the log, and the application list associationed with the client device in the server; and 
     c. may download to the client device, based on the access control list  607  and the management policies, 
     1. a set of applications selected by the client, 
     2. a default set of applications that the client device does not have, and 
     3. a set of applications that are newer versions of the ones owned by the client. 
     After the application distribution manager completes its task, in step  609 , the server sends the updated client application list back to the client to replace the original version, or a new application list if the client device did not have an application list. The connection is terminated in step  608  and the control passes to step  601  to where the server waits for next client request. 
     A server described above may be implemented using a multi-threaded approach. Each time the server accepts a client request, the server spawns off a thread to process this request while the original processing thread continues to waits for other client requests. When the processing of the newly spawned thread is complete, the server simply terminates this thread. In operating systems where multi-thread is not supported, as in some UNIX based systems, each individual thread may be replaced by a separate process. 
     FIG. 7 shows one of the embodiments of the application distribution manager  606  (FIG.  6 ). In step  701  a record from the client application list is read. At step  702  a determination is made whether more records remain in the application list. 
     If no more records remain to be read, the server determines in step  703 , using the access control list whether there are new applications to be added to this client&#39;s application list. If there are no new applications to be added the application distribution manager process is terminated in step  710 . However, if there are new applications to be added, the server adds these new applications to the client application list in step  709 , and then the application distribution manager process is terminated in step  710 . 
     In the embodiment of the application distribution manager shown in FIG. 7, the process adds new applications to the application list in step  709  based on access control list  607  (FIG.  6 ). An alternative embodiment may examine each newly added application in the updated application list and download the applications that belong to a default set of applications for this client. 
     The server may be programmed to keep a list of times when each client last conducted application distribution request and when the access control list was last changed. If the access control list has not been changed since this client&#39;s last request, then the decision step  703  and a possible step  709  can be avoided and the application distribution manager process will be terminated in step  710 . 
     If there are more records to be read, then for each record read from the client application list, the server determines in step  704 , using the access control list whether the application in this record is still authorized for download to the client user and device. This is so because the access control policy may change from time to time and the application authorized for this client may loose the authorization and may have to be taken out from the client application list. 
     Therefore, if the application of the current record has become unauthorized by this client, the server then removes this application from the client application list in step  705  and will return to read the next record in step  701 . 
     The server may be programmed to keep a list of times when this client last conducted application distribution request and when the access control list was last changed. If the access control list has not been changed since this client&#39;s last request, the step  704  can be avoided and the server proceeds from step  702  directly to step  706 . 
     If the application in the current record read from the application list is still authorized, the server continues processing in step  706 , where it determines whether the status of this application in the client application list is marked “download,” “delete,” or “no change.” 
     The decision of the status “download,” “delete,” and “no change” can be based on the new access control list  607  (FIG. 6) or management policies. For example, a server may download an application to a client device if this application is found in a default set of applications required by this client which does not already have it, or this application is a new version of an older application existing in the client device, or it is selected by the client for download which is allowed by the access control list  607  (FIG.  6 ). 
     If the status is marked “no change,” nothing further needs to be done for this application, therefore the processing will continue at step  701 , where the next record is read. 
     If the status is marked “download,” in step  707 , this application is either 
     a. downloaded from the server to the client device, or 
     b. mark this application to be download later and after all the records in the client application list are read and all applications are marked for download, the server can download all marked applications to the client device before disconnecting. 
     In step  708  the server version of the application list associated with this client device and the logs are updated to reflect the current status and the processing continues at step  701 , where the next record is read. 
     If the status is marked “delete,” this application is deleted from the client device. In step  708  the server version of the application list associated with this client device and the logs are updated to reflect the current status and the processing continues at step  701 , where the next record is read. 
     While the invention has been particularly shown and described with respect to illustrative and preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention that should be limited only by the scope of the appended claims.