Abstract:
At least one file containing information is transferred across a distributed network environment. The information allows at least one application configured to execute on at least one client workstation to display a portion of a distributed hypermedia document within a browser-controlled window, to respond to text formats to initiate processing specified by the text formats, to identify an embed text format which corresponds to a first location in the distributed hypermedia document and to automatically invoke program code being part of a distributed application located on two or more computers coupled to the distributed hypermedia network, in response to the identifying of the embed text format, in order to enable an end-user to directly interact with an object when the object is displayed within a display area created at the first location within the portion of the distributed hypermedia document being displayed in the browser-controlled window.

Description:
RELATED APPLICATIONS 
     This application is a continuation and claims the benefit of U.S. application Ser. No. 11/593,258 filed Nov. 2, 2006, which is a continuation and claims the benefit of U.S. application Ser. No. 10/217,955 filed Aug. 9, 2002, now U.S. Pat. No. 7,559,985 which is a continuation and claims the benefit of U.S. application Ser. No. 09/075,359 filed May 8, 1998, now abandoned, which is a continuation and claims the benefit of U.S. application Ser. No. 08/324,443 filed Oct. 17, 1994, now U.S. Pat. No. 5,838,906, the disclosures of which are all hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to manipulating data in a computer network, and specifically to retrieving, presenting and manipulating embedded program objects in distributed hypermedia systems. 
     Computer networks are becoming increasingly popular as a medium for locating and accessing a wide range of data from locations all over the world. The most popular global network is the Internet with millions of computer systems connected to it. The Internet has become popular due to widely adopted standard protocols that allow a vast interconnection of computers and localized computer networks to communicate with each other. Computer systems connected to a network such as the Internet may be of varying types, e.g., mainframes, workstations, personal computers, etc. The computers are manufactured by different companies using proprietary hardware and operating systems and thus have incompatibilities in their instruction sets, busses, software, file formats and other aspects of their architecture and operating systems. Localized computer networks connected to the Internet may be incompatible with other computer systems and localized networks in terms of the physical layer of communication including the specific hardware used to implement the network. Also, different networks use differing, incompatible protocols for transferring information and are not able to communicate with each other without a translation mechanism such as a “gateway”. 
     The Internet provides a uniform and open standard for allowing various computers and networks to communicate with each other. For example, the Internet uses Transfer Control Protocol/Internet Protocol (“TCP/IP”) that defines a uniform packet-switched communication standard which is ultimately used in every transfer of information that takes place over the Internet. 
     Other Internet standards are the HyperText Transmission Protocol (“HTTP”) that allows hypertext documents to be exchanged freely among any computers connected to the Internet and HyperText Markup Language (“HTML”) that defines the way in which hypertext documents designate links to information. See, e.g., Berners-Lee, T. J., “The world-wide web,” Computer Networks and ISDN Systems 25 (1992). 
     A hypertext document is a document that allows a user to view a text document displayed on a display device connected to the user&#39;s computer and to access, retrieve and view other data objects that are linked to hypertext words or phrases in the hypertext document. In a hypertext document, the user may “click on,” or select, certain words or phrases in the text that specify a link to other documents, or data objects. In this way, the user is able to navigate easily among data objects. The data objects may be local to the user&#39;s computer system or remotely located over a network. An early hypertext system is Hypercard, by Apple Computer, Inc. Hypercard is a standalone system where the data objects are local to the user&#39;s system. 
     When a user selects a phrase in a hypertext document that has an associated link to another document, the linked document is retrieved and displayed on the user&#39;s display screen. This allows the user to obtain more information in an efficient and easy manner. This provides the user with a simple, intuitive and powerful way to “branch off” from a main document to learn more about topics of interest. 
     Objects may be text, images, sound files, video data, documents or other types of information that is presentable to a user of a computer system. When a document is primarily text and includes links to other data objects according to the hypertext format, the document is said to be a hypertext document. When graphics, sound, video or other media capable of being manipulated and presented in a computer system is used as the object linked to, the document is said to be a hypermedia document. A hypermedia document is similar to a hypertext document, except that the user is able to click on images, sound icons, video icons, etc., that link to other objects of various media types, such as additional graphics, sound, video, text, or hypermedia or hypertext documents. 
       FIG. 1  shows examples of hypertext and hypermedia documents and links associating data objects in the documents to other data objects. Hypermedia document  10  includes hypertext  20 , an image icon at  22 , a sound icon at  24  and more hypertext  26 . FIG.  1  shows hypermedia document  10  substantially as it would appear on a user&#39;s display screen. The user is able to select, or “click” on icons and text on a display screen by using an input device, such as a mouse, in a manner well-known in the art. 
     When the user clicks on the phrase “hypermedia,” software running on the user&#39;s computer obtains the link associated with the phrase, symbolically shown by arrow  30 , to access hypermedia document  14 . Hypermedia document  14  is retrieved and displayed on the user&#39;s display screen. Thus, the user is presented with more information on the phrase “hypermedia.” The mechanism for specifying and locating a linked object such as hypermedia document  14  is an HTML “element” that includes an object address in the format of a Uniform Resource Locator (URL). 
     Similarly, additional hypertext  26  can be selected by the user to access hypertext document  12  via link  32  as shown in  FIG. 1 . If the user selects additional hypertext  26 , then the text for hypertext document  12  is displayed on the user screen. Note that hypertext document  12 , itself, has hypertext at  28 . Thus, the user can click on the phrase “hypermedia” while viewing document  12  to access hypermedia document  14  in a manner similar to that discussed above. 
     Documents, and other data objects, can be referenced by many links from many different source documents.  FIG. 1  shows document  14  serving as a target link for both documents  10  and  12 . A distributed hypertext or hypermedia document typically has many links within it that specify many different data objects located in computers at different geographical locations connected by a network. Hypermedia document  10  includes image icon  22  with a link to image  16 . One method of viewing images is to include an icon, or other indicator, within the text. 
     Typically, the indicator is a very small image and may be a scaled down version of the full image. The indicator may be shown embedded within the text when the text is displayed on the display screen. The user may select the indicator to obtain the full image. When the user clicks on image icon  22  browser software executing on the user&#39;s computer system retrieves the corresponding full image, e.g., a bit map, and displays it by using external software called a “viewer.” This results in the full image, represented by image  16 , being displayed on the screen. 
     An example of a browser program is the National Center for Supercomputing Application&#39;s (NCSA) Mosaic software developed by the University of Illinois at Urbana/Champaign, Ill. Another example is “Cello” available on the Internet at http://www.law.cornell.edu/. Many viewers exist that handle various file formats such as “.TIF,” “.GIF,” formats. When a browser program invokes a viewer program, the viewer is launched as a separate process. The view displays the full image in a separate “window” (in a windowing environment) or on a separate screen. This means that the browser program is no longer active while the viewer is active. By using indicators to act as place holders for full images that are retrieved and displayed only when a user selects the indicator, data traffic over the network is reduced. Also, since the retrieval and display of large images may require several seconds or more of transfer time the user does not have to wait to have images transferred that are of no interest to the user. 
     Returning to  FIG. 1 , another type of data object is a sound object shown as sound icon  24  within the hypermedia document. When the user selects sound icon  24 , the user&#39;s computer accesses sound data shown symbolically by data file  40 . The accessed sound data plays through a speaker or other audio device. 
     As discussed above, hypermedia documents allow a user to access different data objects. The objects may be text, images, sound files, video, additional documents, etc. As used in this specification, a data object is information capable of being retrieved and presented to a user of a computer system. Some data objects include executable code combined with data. An example of such a combination is a “self-extracting” data object that includes code to “unpack” or decompress data that has been compressed to make it smaller before transferring. When a browser retrieves an object such as a self-extracting data object the browser may allow the user to “launch” the self-extracting data object to automatically execute the unpacking instructions to expand the data object to its original size. Such a combination of executable code and data is limited in that the user can do no more than invoke the code to perform a singular function such as performing the self-extraction after which time the object is a standard data object. 
     Other existing approaches to embedding interactive program objects in documents include the Object Linking and Embedding (OLE) facility in Microsoft Windows, by Microsoft Corp., and OpenDoc, by Apple Computer, Inc. At least one shortcoming of these approaches is that neither is capable of allowing a user to access embedded interactive program objects in distributed hypermedia documents over networks. 
       FIG. 2  is an example of a computer network. In  FIG. 2 , computer systems are connected to Internet  100 , although in practice Internet  100  may be replaced by any suitable computer network. In  FIG. 2 , a user  102  operates a small computer  104 , such as a personal computer or a work station. The user&#39;s computer is equipped with various components, such as user input devices (mouse, trackball, keyboard, etc.), a display device (monitor, liquid crystal display (LCD), etc.), local storage (hard disk drive, etc.), and other components. Typically, small computer  104  is connected to a larger computer, such as server A at  106 . The larger computer may have additional users and computer systems connected to it, such as computer  108  operated by user  110 . Any group of computers may form a localized network. A localized network does not necessarily adopt the uniform protocols of the larger interconnecting network (i.e., Internet  100 ) and is more geographically constrained than the larger network. The localized network may connect to the larger network through a “gateway” or “node” implemented on, for example, a server. 
     Internet  100  connects other localized networks, such as server B at  120 , which interconnects users  122 ,  124  and  126  and their respective computer systems to Internet  100 . Internet  100  is made up of many interconnected computer systems and communication links. Communication links may be by hardwire, fiber optic cable, satellite or other radio wave propagation, etc. Data may move from server A to server B through any number of intermediate servers and communication links or other computers and data processing equipment not shown in  FIG. 2  but symbolically represented by Internet  100 . 
     A user at a workstation or personal computer need not connect to the Internet via a larger computer, such as server A or server B. This is shown, for example, by small computer  130  connected directly to Internet  100  as by a telephone modem or other link. Also, a server need not have users connected to it locally, as is shown by server C at  132  of  FIG. 2 . Many configurations of large and small computers are possible. 
     Typically, a computer on the Internet is characterized as either a “client” or “server” depending on the role that the computer is playing with respect to requesting information or providing information. Client computers are computers that typically request information from a server computer which provides the information. For this reason, servers are usually larger and faster machines that have access to many data files, programs, etc., in a large storage associated with the server. However, the role of a server may also be adopted by a smaller machine depending on the transaction. That is, user  110  may request information via their computer  108  from server A. At a later time, server A may make a request for information from computer  108 . In the first case, where computer  108  issues a request for information from server A, computer  108  is a “client” making a request of information from server A. Server A may have the information in a storage device that is local to Server A or server A may have to make requests of other computer systems to obtain the information. User  110  may also request information via their computer  108  from a server, such as server B located at a remote geographical location on the Internet. However, user  110  may also request information from a computer, such as small computer  124 , thus placing small computer  124  in the role of a “server.” For purposes of this specification, client and server computers are categorized in terms of their predominant role as either an information requestor or provider. Clients are generally information requestors, while servers are generally information providers. 
     Referring again to  FIG. 1 , data objects such as distributed hypermedia documents  10 ,  12  and  14 , image  16  and sound data file  40 , may be located at any of the computers shown in  FIG. 2 . Since these data objects may be linked to a document located on another computer the Internet allows for remote object linking. 
     For example, hypertext document  10  of  FIG. 1  may be located at user  110 &#39;s client computer  108 . When user  110  makes a request by, for example, clicking on hypertext  20  (i.e., the phrase “hypermedia”), user  110 &#39;s small client computer  108  processes links within hypertext document  10  to retrieve document  14 . In this example, we assume that document  14  is stored at a remote location on server B. Thus, in this example, computer  108  issues a command that includes the address of document  14 . This command is routed through server A and Internet  100  and eventually is received by server B. Server B processes the command and locates document  14  on its local storage. Server  14  then transfers a copy of the document back to client  108  via Internet  100  and server A. After client computer  108  receives document  14 , it is displayed so that user  110  may view it. 
     Similarly, image object  16  and sound data file  40  may reside at any of the computers shown in  FIG. 2 . Assuming image object  16  resides on server C when user  110  clicks on image icon  22 , client computer  108  generates a command to retrieve image object  16  to server C. Server C receives the command and transfers a copy of image object  16  to client computer  108 . Alternatively, an object, such as sound data file  40 , may reside on server A so that it is not necessary to traverse long distances via the Internet in order to retrieve the data object. 
     The Internet is said to provide an “open distributed hypermedia system.” It is an “open” system since Internet  100  implements a standard protocol that each of the connecting computer systems,  106 ,  130 ,  120 ,  132  and  134  must implement (TCP/IP). It is a “hypermedia” system because it is able to handle hypermedia documents as described above via standards such as the HTTP and HTML hypertext transmission and mark up standards, respectively. Further, it is a “distributed” system because data objects that are imbedded within a document may be located on many of the computer systems connected to the Internet. An example of an open distributed hypermedia system is the so-called “world-wide web” implemented on the Internet and discussed in papers such as the Berners-Lee reference given above. 
     The open distributed hypermedia system provided by the Internet allows users to easily access and retrieve different data objects located in remote geographic locations on the Internet. However, this open distributed hypermedia system as it currently exists has shortcomings in that today&#39;s large data objects are limited largely by bandwidth constraints in the various communication links in the Internet and localized networks, and by the limited processing power, or computing constraints, of small computer systems normally provided to most users. Large data objects are difficult to update at frame rates fast enough (e.g., 30 frames per second) to achieve smooth animation. Moreover, the processing power needed to perform the calculations to animate such images in real time does not exist on most workstations, not to mention personal computers. Today&#39;s browsers and viewers are not capable of performing the computation necessary to generate and render new views of these large data objects in real time. 
     For example, the Internet&#39;s open distributed hypermedia system allows users to view still images. These images are simple non-interactive two-dimensional images, similar to photographs. Much digital data available today exists in the form of high-resolution multi-dimensional image data (e.g., three dimensional images) which is viewed on a computer while allowing the user to perform real time viewing transformations on the data in order for the user to better understand the data. 
     An example of such type of data is in medical imaging where advanced scanning devices, such as Magnetic Resonance Imaging (MRI) and Computed Tomography (CT), are widely used in the fields of medicine, quality assurance and meteorology to present physicians, technicians and meteorologists with large amounts of data in an efficient way. Because visualization of the data is the best way for a user to grasp the data&#39;s meaning, a variety of visualization techniques and real time computer graphics methods have been developed. However, these systems are bandwidth-intensive and compute-intensive and often require multiprocessor arrays and other specialized graphics hardware to carry them out in real time. Also, large amounts of secondary storage for data are required. The expense of these requirements has limited the ability of researchers to readily exchange findings since these larger computers required to store, present and manipulate images are not available to many of the researchers that need to have access to the data. 
     On the other hand, small client computers in the form of personal computers or workstations such as client computer  108  of  FIG. 2  are generally available to a much larger number of researchers. Further, it is common for these smaller computers to be connected to the Internet. Thus, it is desirable to have a system that allows the accessing, display and manipulation of large amounts of data, especially image data, over the Internet to a small, and relatively cheap, client computer. 
     Due to the relatively low bandwidth of the Internet (as compared to today&#39;s large data objects) and the relatively small amount of processing power available at client computers, many valuable tasks performed by computers cannot be performed by users at client computers on the Internet. Also, while the present open distributed hypermedia system on the Internet allows users to locate and retrieve data objects it allows users very little, if any, interaction with these data objects. Users are limited to traditional hypertext and hypermedia forms of selecting linked data objects for retrieval and launching viewers or other forms of external software to have the data objects presented in a comprehensible way. 
     Thus, it is desirable to have a system that allows a user at a small client computer connected to the Internet to locate, retrieve and manipulate data objects when the data objects are bandwidth-intensive and compute-intensive. Further, it is desirable to allow a user to manipulate data objects in an interactive way to provide the user with a better understanding of information presented and to allow the user to accomplish a wider variety of tasks. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a method for running embedded program objects in a computer network environment. The method includes the steps of providing at least one client workstation and one network server coupled to the network environment where the network environment is a distributed hypermedia environment; displaying, on the client workstation, a portion of a hypermedia document received over the network from the server, where the hypermedia document includes an embedded controllable application; and interactively controlling the embedded controllable application from the client workstation via communication sent over the distributed hypermedia environment. 
     The present invention allows a user at a client computer connected to a network to locate, retrieve and manipulate objects in an interactive way. The invention not only allows the user to use a hypermedia format to locate and retrieve program objects, but also allows the user to interact with an application program located at a remote computer. Interprocess communication between the hypermedia browser and the embedded application program is ongoing after the program object has been launched. The user is able to use a vast amount of computing power beyond that which is contained in the user&#39;s client computer. 
     In one application, high resolution three dimensional images are processed in a distributed manner by several computers located remotely from the user&#39;s client computer. This amounts to providing parallel distributed processing for tasks such as volume rendering or three dimensional image transformation and display. Also, the user is able to rotate, scale and otherwise reposition the viewpoint with respect to these images without exiting the hypermedia browser software. The control and interaction of viewing the image may be provided within the same window that the browser is using assuming the environment is a “windowing” environment. The viewing transformation and volume rendering calculations may be performed by remote distributed computer systems. 
     Once an image representing a new viewpoint is computed the frame image is transmitted over the network to the user&#39;s client computer where it is displayed at a designated position within a hypermedia document. By transmitting only enough information to update the image, the need for a high bandwidth data connection is reduced. Compression can be used to further reduce the bandwidth requirements for data transmission. 
     Other applications of the invention are possible. For example, the user can operate a spreadsheet program that is being executed by one or more other computer systems connected via the network to the user&#39;s client computer. Once the spreadsheet program has calculated results, the results may be sent over the network to the user&#39;s client computer for display to the user. In this way, computer systems located remotely on the network can be used to provide the computing power that may be required for certain tasks and to reduce the data bandwidth by only transmitting results of the computations. 
     Still other applications of the present invention are possible, as disclosed in the specification, below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates examples of hypertext and hypermedia documents and links; 
         FIG. 2  is an example of a computer network; 
         FIG. 3  is an illustration of a computer system suitable for use with the present invention; 
         FIG. 4  is an illustration of basic subsystems in the computer system of  FIG. 3 ; 
         FIG. 5  is an illustration of an embodiment of the invention using a client computer, server computer and a network; 
         FIG. 6  shows another embodiment of the present invention using additional computers on the network; 
         FIG. 7A  is a flowchart of some of the functionality within the HTMLparse.c file; 
         FIG. 7B  is a flowchart of some of the functionality within the HTMLformat.c file; 
         FIG. 8A  is a flowchart of some of the functionality within the HTMLwidget.c file; 
         FIG. 8B  is a flowchart of some of the functionality within the HTML.c file; 
         FIG. 9  is a screen display generated in accordance with the present invention; and 
         FIG. 10  is a diagram of the various processes and data paths in the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     375 pages of Source code on 4 microfiche Appendices A and B are provided to this specification. The source code should be consulted to provide details of a specific embodiment of the invention in conjunction with the discussion of the routines in this specification. The source code in Appendix A includes NCSA Mosaic version 2.4 source code along with modifications to the source code to implement the present invention. Appendix B includes source code implementing an application program interface. The source code is written in the “C” computer language to run on an X-Window platform. 
       FIG. 3  is an illustration of a computer system suitable for use with the present invention.  FIG. 3  depicts but one example of many possible computer types or configurations capable of being used with the present invention.  FIG. 3  shows computer system  150  including display device  153 , display screen  155 , cabinet  157 , keyboard  159  and mouse  161 . 
     Mouse  161  and keyboard  159  are “user input devices.” Other examples of user input devices are a touch screen, light pen, track ball, data glove, etc. Mouse  161  may have one or more buttons such as buttons  163  shown in  FIG. 3 . Cabinet  157  houses familiar computer components such as disk drives, a processor, storage means, etc. As used in this specification “storage means” includes any storage device used in connection with a computer system such as disk drives, magnetic tape, solid state memory, bubble memory, etc. Cabinet  157  may include additional hardware such as input/output (I/O) interface cards for connecting computer system  150  to external devices such as an optical character reader, external storage devices, other computers or additional devices. 
       FIG. 4  is an illustration of basic subsystems in computer system  150  of  FIG. 3 . In  FIG. 4 , subsystems are represented by blocks such as central processor  180 , system memory  181  consisting of random access memory (RAM) and/or read-only memory (ROM), display adapter  182 , monitor  183  (equivalent to display device  153  of  FIG. 3 ), etc. The subsystems are interconnected via a system bus  184 . Additional subsystems such as a printer, keyboard, fixed disk and others are shown. Peripherals and input/output (I/O) devices can be connected to the computer system by, for example serial port  185 . For example, serial port  185  can be used to connect the computer system to a modem for connection to a network or serial port  185  can be used to interface with a mouse input device. The interconnection via system bus  184  allows central processor  180  to communicate with each subsystem and to control the execution of instructions from system memory  181  or fixed disk  186 , and the exchange of information between subsystems. Other arrangements of subsystems and interconnections are possible. 
       FIG. 5  is an illustration of an embodiment of the invention using a client computer, server computer and a network. 
     In  FIG. 5 , client computer  200  communicates with server computer  204  via network  206 . Both client computer  200  and server computer  204  use a network protocol layer to communicate with network  206 . In a preferred embodiment, network  206  is the Internet and the network protocol layers are TCP/IP. Other networks and network protocols may be used. For ease of illustration, additional hardware and software layers are not shown in  FIG. 5 . 
     Client computer  200  includes processes, such as browser client  208  and application client  210 . In a preferred embodiment, application client  210  is resident within client computer  200  prior to browser client  208 &#39;s parsing of a hypermedia document as discussed below. In a preferred embodiment application client  210  resides on the hard disk or RAM of client computer  200  and is loaded (if necessary) and executed when browser client  208  detects a link to application client  210 . The preferred embodiment uses the XEvent interprocess communication protocol to exchange information between browser client  208  and application client  210  as described in more detail, below. Another possibility is to install application client  210  as a “terminate and stay resident” (TSR) program in an operating system environment, such as X-Window. Thereby making access to application client  210  much faster. 
     Browser client  208  is a process that a user of client computer  200  invokes in order to access various data objects, such as hypermedia documents, on network  206 . Hypermedia document  212  shown within client computer  200  is an example of a hypermedia document, or object, that a user has requested access to. In this example, hypermedia document  212  has been retrieved from a server connected to network  206  and has been loaded into, e.g., client computer  200 &#39;s RAM or other storage device. 
     Once hypermedia document  212  has been loaded into client computer  200 , browser client  208  parses hypermedia document  212 . In parsing hypermedia document  212 , browser client  208  detects links to data objects as discussed above in the Background of the Invention section. In  FIG. 5 , hypermedia document  212  includes an embedded program link at  214 . Embedded program link  214  identifies application client  212  as an application to invoke. In this present example, the application, namely, application client  210 , resides on the same computer as the browser client  208  that the user is executing to view the hypermedia document. Embedded program link  214  may include additional information, such as parameters, that tell application client  210  how to proceed. For example, embedded program link  214  may include a specification as to a data object that application client  210  is to retrieve and process. 
     When browser client  208  encounters embedded program link  214 , it invokes application client  210  (optionally, with parameters or other information) and application client  210  executes instructions to perform processing in accordance with the present invention. 
     An example of the type of processing that application client  210  may perform is multidimensional image visualization. Note that application client  210  is in communication with network  206  via the network protocol layer of client computer  200 . This means that application client  210  can make requests over network  206  for data objects, such as multidimensional image objects. For example, application client  210  may request an object, such as object  1  at  216 , located in server computer  204 . Application client  210  may make the request by any suitable means. Assuming network  206  is the Internet, such a request would typically be made by using HTTP in response to a HTML-style link definition for embedded program link  214 . 
     Assuming application client  210  has made a request for the data object at  216 , server process  218  ultimately receives the request. Server process  218  then retrieves data object  216  and transfers it over network  206  back to application client  210 . To continue with the example of a multidimensional visualization application, data object  216  may be a three dimensional view of medical data for, e.g., an embryo. 
     After application client  210  receives the multidimensional data object  216 , application client  210  executes instructions to display the multidimensional embryo data on the display screen to a user of the client computer  200 . The user is then able to interactively operate controls to recompute different views for the image data. In a preferred embodiment, a control window is displayed within, or adjacent to, a window generated by browser client  208  that contains a display of hypermedia document  212 . An example of such display is discussed below in connection with  FIG. 9 . Thus, the user is able to interactively manipulate a multidimensional image object by means of the present invention. In order to make application client  210  integral with displays created by browser client  208 , both the browser client and the application client must be in communication with each other, as shown by the arrow connecting the two within client computer  200 . The manner of communication is through an application program interface (API), discussed below. 
     Browser client  208  is a process, such as NCSA Mosaic, Cello, etc. Application client  210  is embodied in software presently under development called “VIS” and “Panel” created by the Center for Knowledge Management at the University of California, San Francisco, as part of the Doyle Group&#39;s distributed hypermedia object embedding approach described in “Integrated Control of Distributed Volume Visualization Through the World-Wide-Web,” by C. Ang, D. Martin, M. Doyle; to be published in the Proceedings of Visualization  1994 , IEEE Press, Washington, D.C., October 1994. 
     Versions and descriptions of software embodying the present invention are generally available as hyperlinked data objects from the Visible Embryo Project&#39;s World Wide Web document at the URL address “HTTP://visembryo.ucsf.edu/”. 
     Another embodiment of the present invention uses an application server process executing on server computer  204  to assist in processing that may need to be performed by an external program. For example, in  FIG. 5 , application server  220  resides on server computer  204 . Application server  220  works in communication with application client  210  residing on client computer  200 . In a preferred embodiment, application server  220  is called VRServer, also a part of Doyle Group&#39;s approach. Since server computer  204  is typically a larger computer having more data processing capabilities and larger storage capacity, application server  220  can operate more efficiently, and much faster, than application client  210  in executing complicated and numerous instructions. 
     In the present example where a multidimensional image object representing medical data for an embryo is being viewed, application server  220  could perform much of the viewing transformation and volume rendering calculations to allow a user to interactively view the embryo data at their client computer display screen. In a preferred embodiment, application client  210  receives signals from a user input device at the user&#39;s client computer  200 . An example of such input would be to rotate the embryo image from a current position to a new position from the user&#39;s point of view. This information is received by application client  210  and processed to generate a command sent over network  206  to application server  220 . Once application server  220  receives the information in the form of, e.g., a coordinate transformation for a new viewing position, application server  220  performs the mathematical calculations to compute a new view for the embryo image. Once the new view has been computed, the image data for the new view is sent over network  206  to application client  210  so that application client  210  can update the viewing window currently displaying the embryo image. In a preferred embodiment, application server  220  computes a frame buffer of raster display data, e.g., pixel values, and transfers this frame buffer to application client  210 . Techniques, such as data compression and delta encoding, can be used to compress the data before transmitting over network  206  to reduce the bandwidth requirement. 
     It will be readily seen that application server  220  can advantageously use server computer  204 &#39;s computing resources to perform the viewing transformation much more quickly than could application client  210  executing on client computer  200 . Further, by only transmitting the updated frame buffer containing a new view for the embryo image, the amount of data sent over network  206  is reduced. By using appropriate compression techniques, such as, e.g., MPEG (Motion Picture Experts Group) or JPEG (Joint Photographic Experts Group), efficient use of network  206  is preserved. 
       FIG. 6  shows yet another embodiment of the present invention.  FIG. 6  is similar to  FIG. 5 , except that additional computers  222  and  224  are illustrated. Each additional computer includes a process labeled “Application (Distributed).” The distributed application performs a portion of the task that an application, such as application server  220  or application client  210 , perform. In the present. example, tasks such as volume rendering may be broken up and easily performed among two or more computers. These computers can be remote from each other on network  206 . Thus, several computers, such as server computer  204  and additional computers  222  and  224  can all work together to perform the task of computing a new viewpoint and frame buffer for the embryo for the new orientation of the embryo image in the present example. The coordination of the distributed processing can be performed at client computer  200  by application client  210 , at server computer  204  by application server  220 , or by any of the distributed applications executing on additional computers, such as  222  and  224 . In a preferred embodiment, distributed processing is coordinated by a program called “VIS” represented by application client  210  in  FIG. 6 . 
     Other applications of the invention are possible. For example, the user can operate a spreadsheet program that is being executed by one or more other computer systems connected via the network to the user&#39;s client computer. Once the spreadsheet program has calculated results, those results may be sent over the network to the user&#39;s client computer for display within the hypermedia document on the user&#39;s client computer. In this way, computer systems located remotely on the network can be used to provide the computing power that may be required for certain tasks and to reduce the data bandwidth required by only transmitting results of the computations. 
     Another type of possible application of this invention would involve embedding a program which runs only on the client machine, but which provides the user with more functionality than exists in the hypermedia browser alone. An example of this is an embedded client application which is capable of viewing and interacting with images which have been processed with Dr. Doyle&#39;s MetaMAP invention (U.S. Pat. No. 4,847,604). This MetaMAP process uses object-oriented color map processing to allow individual color index ranges within paletted images to have object identities, and is useful for the creation of, for example, interactive picture atlases. It is a more efficient means for defining irregular “hotspots” on images than the ISMAP function of the World Wide Web, which uses polygonal outlines to define objects in images. A MetaMAP-capable client-based image browser application can be embedded, together with an associated image, within a hypermedia document, allowing objects within the MetaMAP-processed image to have URL addresses associated with them. When a user clicks with a mouse upon an object within the MetaMAP-processed image, the MetaMAP client application relays the relevant URL back to the hypermedia browser application, which then retrieves the HTML file or hypermedia object which corresponds to that URL. 
     The various processes in the system of the present invention communicate through a custom API called Mosaic/External Application Program Interface MEAPI. The MEAPI set of predefined messages includes those shown in Table I. 
     
       
         
               
             
               
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                 Message Function Message Name 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                   
                 Messages from server to client: 
                   
               
               
                   
                   
                 1. Server Update Done 
                   
               
               
                   
                   
                 XtNrefreshNotify 
                   
               
               
                   
                   
                 2. Server Ready XtNpanelStartNotify 
                   
               
               
                   
                   
                 3. Server Exiting XtNpanelExitNotify 
                   
               
               
                   
                   
                 Messages from client to server: 
                   
               
               
                   
                   
                 4. Area Shown XtNmapNotify 
                   
               
               
                   
                   
                 5. Area Hidden XtNunmapNotify 
                   
               
               
                   
                   
                 6. Area Destroyed XtNexitNotify 
               
               
                   
                   
               
             
          
         
       
     
     The messages in Table I are defined in the file protocol.sub.--lib.h in Appendix B. The functions of the MEAPI are provided in protocol.sub.--lib.c of Appendix B. Thus, by using MEAPI a server process communicates to a client application program to let the client application know when the server has finished updating information, such as an image frame buffer, or pixmap (Message 1); when the server is ready to start processing messages (Message 2) and when the server is exiting or stopping computation related to the server application program. 
     For client to server communications, MEAPI provides for the client informing the server when the image display window area is visible, when the area is hidden and when the area is destroyed. Such information allows the server to decide whether to allocate computing resources for, e.g., rendering and viewing transformation tasks where the server is running an application program to generate new views of a multi dimensional object. Source code for MEAPI fundamental functions such as handle.sub.--client.sub.--msg, register.sub.--client, register.sub.--client.sub.--msg.sub.--callback and send.sub.--client.sub.--msg may be found in protocol.sub.--lib.c as part of the source code in Appendix B. Next, a discussion of the software processes that perform parsing of a hypermedia document and launching of an application program is provided in connection with Table II and  FIGS. 7A ,  7 B,  8 A and  8 B. Table II, below, shows an example of an HTML tag format used by the present invention to embed a link to an application program within a hypermedia document. 
     For client to server communications, MEAPI provides for the client informing the server when the image display window area is visible, when the area is hidden and when the area is destroyed. Such information allows the server to decide whether to allocate computing resources for, e.g., rendering and viewing transformation tasks where the server is running an application program to generate new views of a multi dimensional object. Source code for MEAPI fundamental functions such as handle.sub.--client.sub.--msg, register.sub.--client, register.sub.--client.sub.--msg.sub.--callback and send.sub.--client.sub.--msg may be found in protocol.sub.--lib.c as part of the source code in Appendix B. 
     Next, a discussion of the software processes that perform parsing of a hypermedia document and launching of an application program is provided in connection with Table II and  FIGS. 7A ,  7 B,  8 A and  8 B. 
     Table II, below, shows an example of an HTML tag format used by the present invention to embed a link to an application program within a hypermedia document. 
     
       
         
               
               
               
               
             
           
               
                   
                 TABLE II 
               
               
                   
                   
               
             
             
               
                   
                   
                 &amp; lt EMBED 
                   
               
               
                   
                   
                 TYPE = “type” 
                   
               
               
                   
                   
                 HREF = “href” 
                   
               
               
                   
                   
                 WIDTH = width 
                   
               
               
                   
                   
                 HEIGHT = height 
                   
               
               
                   
                   
                 &amp; gt 
               
               
                   
                   
               
             
          
         
       
     
     As shown in Table II, the EMBED tag includes TYPE, HREF, WIDTH and HEIGHT elements. The TYPE element is a Multipurpose Internet Mail Extensions (MIME) type. Examples of values for the TYPE element are “application/x-vis” or “video/mpeg”. The type “application/x-vis” indicates that an application named “x-vis” is to be used to handle the object at the URL specified by the HREF. Other types are possible such as “application/x-inventor”, “application/postscript” etc. In the case where TYPE is “application/x-vis” this means that the object at the URL address is a three dimensional image object since the program “x-vis” is a data visualization tool designed to operate on three dimensional image objects. However, any manner of application program may be specified by the TYPE element so that other types of applications, such as a spreadsheet program, database program, word processor, etc. may be used with the present invention. Accordingly, the object reference by the HREF element would be, respectively, a spreadsheet object, database object, word processor document object, etc. 
     On the other hand, TYPE values such as “video/mpeg”, “image/gif”, “video/x-sgi-movie”, etc. describe the type of data that HREF specifies. This is useful where an external application program, such as a video player, needs to know what format the data is in, or where the browser client needs to determine which application to launch based on the data format. Thus, the TYPE value can specify either an application program or a data type. Other TYPE values are possible. HREF specifies a URL address as discussed above for a data object. Where TYPE is “application/x-vis” the URL address specifies a multi-dimensional image object. Where TYPE is “video/mpeg” the URL address specifies a video object. 
     WIDTH and HEIGHT elements specify the width and height dimensions, respectively, of a Distributed Hypermedia Object Embedding (DHOE) window to display an external application object such as the three dimensional image object or video object discussed above. 
       FIG. 7A  is a flowchart describing some of the functionality within the HTMLparse.c file of routines. The routines in HTMLparse.c perform the task of parsing a hypermedia document and detecting the EMBED tag. In a preferred embodiment, the enhancements to include the EMBED tag are made to an HTML library included in public domain NCSA Mosaic version 2.4. Note that much of the source code in is pre-existing NCSA Mosaic code. Only those portions of the source code that relate to the new functionality discussed in this specification should be considered as part of the invention. The new functionality is identifiable as being set off from the main body of source code by conditional compilation macros such as “#ifdef . . . #endif” as will be readily apparent to one of skill in the art. 
     In general, the flowcharts in this specification illustrate one or more software routines executing in a computer system such as computer system  1  of  FIG. 1 . The routines may be implemented by any means as is known in the art. For example, any number of computer programming languages, such as “C”, Pascal, FORTRAN, assembly language, etc., may be used. Further, various programming approaches such as procedural, object oriented or artificial intelligence techniques may be employed. 
     The steps of the flowcharts may be implemented by one or more software routines, processes, subroutines, modules, etc. It will be apparent that each flowchart is illustrative of merely the broad logical flow of the method of the present invention and that steps may be added to, or taken away from, the flowcharts without departing from the scope of the invention. Further, the order of execution of steps in the flowcharts may be changed without departing from the scope of the invention. Additional considerations in implementing the method described by the flowchart in software may dictate changes in the selection and order of steps. Some considerations are event handling by interrupt driven, polled, or other schemes. A multiprocessing or multitasking environment could allow steps to be executed “concurrently.” For ease of discussion the implementation of each flowchart may be referred to as if implemented in a single “routine”. 
     The modifications to NCSA Mosaic version 2.4 software files HTMLparse.c, HTMLformat.c, HTMLwidget.c and HTML.c will next be discussed, in turn. 
     Returning to  FIG. 7 , it is assumed that a hypermedia document has been obtained at a user&#39;s client computer and that a browser program executing on the client computer displays the document and calls a first routine in the HTMLparse.c file called “HTMLparse”. This first routine, HTMLparse, is entered at step  252  where a pointer to the start of the document portion is passed. Steps  254 ,  256  and  258  represent a loop where the document is parsed or scanned for HTML tags or other symbols. While the file HTMLparse.c includes routines to handle all possible tags and symbols that may be encountered,  FIG. 7A , for simplicity, only illustrates the handling of EMBED tags. 
     Assuming there is more text to parse, execution proceeds to step  256  where routines in HTMLparse.c obtain the next item (e.g., word, tag or symbol) from the document. At step  258  a check is made as to whether the current tag is the EMBED tag. If not, execution returns to step  254  where the next tag in the document is obtained. If, at step  258 , it is determined that the tag is the EMBED tag, execution proceeds to step  260  where an enumerated type is assigned for the tag. Each occurrence of a valid EMBED tag specifies an embedded object. HTMLParse calls a routine “get.sub.--mark” in HTMLparse.c to put sections of HTML document text into a “markup” text data structure. Routine get.sub.--mark, in turn, calls ParseMarkType to assign an enumerated type. The enumerated type is an identifier with a unique integer associated with it that is used in later processing described below. 
     Once all of the hypermedia text in the text portion to be displayed has been parsed, execution of HTMLparse.c routines terminates at step  262 . 
       FIG. 7B  is a flowchart of routines in file HTMLformat.c to process the enumerated type created for the EMBED tag by routines in HTMLparse.c. In the X-Window implementation of a preferred embodiment, the enumerated type is processed as if it is a regular Motif/XT widget. For details on X-Window development see, e.g., “Xlib Programming Manual,” “X Toolkit Intrinsics Programming Manual” and “Motif Programming Manual” published by O&#39;Reilly &amp;amp; Associates, Inc. HTMLformat is entered at step  270  where a pointer to the enumerated type to process is passed. 
     At step  272  the parameters of the structure are initialized in preparation for inserting a DrawingArea widget on an HTML page. This includes providing values for the width and height of a window on the display to contain an image, position of the window, style, URL of the image object, etc. Various codes are also added by routines in HTMLformat.c (such as TriggerMarkChanges) to insert an internal representation of the HTML statement into an object list maintained internally by the browser. In the X-Window application corresponding to the source code of Appendix A, the browser is NCSA Mosaic version 2.4. 
       FIG. 8A  is a flowchart for routine HTMLwidget. HTMLwidget creates display data structures and launches an external application program to handle the data object specified by the URL in the EMBED tag. 
     HTMLwidget is entered at step  280  after HTMLformat has created the internal object representation of the EMBED tag. HTMLwidget is passed the internal object and performs its processing on the object. At step  282  the DrawingArea widget is created according to the type of the internal representation, from HTMLformat, specified in the internal object. Similarly, at step  284  a pixmap area for backing storage is defined. 
     At step  286  a check is made as to whether the type attribute of the object, i.e., the value for the TYPE element of the EMBED tag, is an application. If so, step  290  is executed to launch a predetermined application. In a preferred embodiment an application is launched according to a user-defined list of application type/application pairs. The list is defined as a user-configurable XResource as described in “Xlib Programming Manual.” An alternative embodiment could use the MIME database as the source of the list of application type/application pairs. The routine “vis.sub.--start.sub.--external.sub.--application” in file HTMLformat.c is invoked to match the application type and to identify the application to launch. 
     The external application is started as a child process of the current running process (Mosaic), and informed about the window ID of the DrawingArea created in HTMLformat. The external application is also passed information about the ID of the pixmap, the data URL and dimensions. Codes for communication such as popping-up/iconifying, start notification, quit notification and refresh notification with external applications and DrawingArea refreshing are also added. Examples of such codes are (1) “setup/start” in vis.sub.--register.sub.--client and vis.sub.--get panel.sub.--window in HTMLwidgets.c; (2) “handle messages from external applications” in vis.sub.--handle panel.sub.--msg in HTMLwidgets.c; (3) “send messages to external applications” in vis.sub.--send.sub.--msg in HTMLwidgets.c; (4) “terminate external applications” in vis.sub.--exit in HTMLwidgets.c which calls vis.sub.--send.sub.--msg to send a quit message; and (5) “respond to refresh msgs” in vis.sub.--redraw in HTMLwidgets.c. 
     If, at step  286 , the type is determined not to be an application object (e.g., a three dimensional image object in the case of application “x-vis”) a check is made at step  288  to determine if the type is a video object. If so, step  292  is executed to launch a video player application. Parameters are passed to the video player application to allow the player to display the video object within the DrawingArea within the display of the portion of hypermedia document on the client&#39;s computer. Note that many other application objects types are possible as described above. 
       FIG. 8B  is a flowchart for routine HTML. Routine HTML takes care of “shutting down” the objects, data areas, etc. that were set up to launch the external application and display the data object. HTML is entered at step  300  and is called when the display or other processing of the EMBED tag has been completed. At step  302  the display window is removed and the memory areas for the pixmap and internal object structure is made free for other uses. Completion of processing can be by user command or by computer control. 
     The present invention allows a user to have interactive control over application objects such as three dimensional image objects and video objects. In a preferred embodiment, controls are provided on the external applications&#39; user interface. In the case of a VIS/panel application, a process, “panel” creates a graphical user interface (GUI) thru which the user interacts with the data. The application program, VIS, can be executing locally with the user&#39;s computer or remotely on a server, or on one or more different computers, on the network. The application program updates pixmap data and transfers the pixmap data (frame image data) to a buffer to which the browser has access. The browser only needs to respond to the refresh request to copy the contents from the updated pixmap to the DrawingArea. The Panel process sends messages as “Msg” sending performed by routines such as vis.sub.--send.sub.--msg and vis.sub.--handle panel.sub.--msg to send events (mousemove, keypress, etc.) to the external application. 
       FIG. 9  is a screen display of the invention showing an interactive application object (in this case a three dimensional image object) in a window within a browser window. In  FIG. 9 , the browser is NCSA Mosaic version 2.4. The processes VIS, Panel and VRServer work as discussed above.  FIG. 9  shows screen display  356  Mosaic window  350  containing image window  352  and a portion of a panel window  354 . Note that image window  352  is within Mosaic window  350  while panel window  354  is external to Mosaic window  350 . Another possibility is to have panel window  354  within Mosaic window  350 . By using the controls in panel window  354  the user is able to manipulate the image within image window  352  in real time do perform such operations as scaling, rotation, translation, color map selection, etc. In  FIG. 9 , two Mosaic windows are being used to show two different views of an embryo image. One of the views is rotated by six degrees from the other view so that a stereoscopic effect can be achieved when viewing the images. Communication between Panel and VIS is via “Tooltalk” described in, e.g., “Tooltalk 1.1.1 Reference Manual,” from SunSoft. 
       FIG. 10  is an illustration of the processes VIS, Panel and VRServer discussed above. As shown in  FIG. 10 , the browser process, Mosaic, communicates with the Panel process via inter-client communication mechanisms such as provided in the X-Window environment. The Panel process communicates with the VIS process through a communications protocol (ToolTalk, in the preferred embodiment) to exchange visualization command messages and image data. The image data is computed by one or more copies of a process called VRServer that may be executing on remote computers on the network. VRServer processes respond to requests such as rendering requests to generate image segments. The image segments are sent to VIS and combined into a pixmap, or frame image, by VIS. The frame image is then transferred to the Mosaic screen via communications between VIS, Panel and Mosaic. A further description of the data transfer may be found in the paper “Integrated Control of Distributed Volume Visualization Through the World-Wide-Web,” referenced above. 
     In the foregoing specification, the invention has been described with reference to a specific exemplary embodiment thereof. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the appended claims. For example, various programming languages and techniques can be used to implement the disclosed invention. Also, the specific logic presented to accomplish tasks within the present invention may be modified without departing from the scope of the invention. Many such changes or modifications will be readily apparent to one of ordinary skill in the art. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense, the invention being limited only by the provided claims.