Abstract:
A first device presents first information that is associated with a first mode of operation. The first device receives a communication from a second device that is communicably coupled to the first device. The communication instructs the first device to perform an operation corresponding to an event associated with the second device. In response to receiving the communication from the second device, the first device presents second information that is associated with a second mode of operation corresponding to the event associated with the second device. The second information is presented by the first device concurrent with a processing associated with the event that is performed by the second device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation application of and claims priority to U.S. application Ser. No. 14/148,267, filed Jan. 6, 2014, which is a continuation of U.S. application Ser. No. 11/947,707, filed Nov. 29, 2007, now U.S. Pat. No. 8,624,809. The entire contents of each of these applications are hereby incorporated by reference for all purposes. 
    
    
     BACKGROUND 
     This specification is related generally to user interfaces. 
     A computer can include one or more indicators (e.g., lights, light emitting diodes, etc) for providing a status of the computer. A computer can have, for example, a light for conveying information related to the power on/off status, a light for indicating hard disk drive activity, and a light for indicating whether the computer is in “sleep” mode. Generally, the light is operated such that it conveys binary information: power is on or off; there is hard disk drive activity or not; the computer is in sleep mode or not, for example. 
     SUMMARY 
     In general, one aspect of the subject matter described in this specification can be embodied in methods that include the actions of detecting an event that includes an associated sensory output, and, in response to the detected event, emitting a light effect that simulates the sensory output. Other embodiments of this aspect include corresponding systems, apparatus, computer program products, and computer readable media. 
     In general, another aspect of the subject matter described in this specification can be embodied in methods that include the actions of detecting an event, and, in response to the detected event, emitting a light effect that simulates the detected event. Other embodiments of this aspect include corresponding systems, apparatus, computer program products, and computer 
     In another general aspect, a first device presents first information that is associated with a first mode of operation. The first device receives a communication from a second device that is communicably coupled to the first device, the communication instructing the first device to perform an operation corresponding to an event associated with the second device. In response to receiving the communication from the second device, the first device presents second information that is associated with a second mode of operation corresponding to the event associated with the second device. The second information is presented by the first device concurrent with a processing associated with the event that is performed by the second device. 
     Particular implementations of this aspect may include one or more of the following features. Presenting the first information associated with the first mode of operation may comprise presenting information associated with a normal mode of operation of the device, wherein the first information may include one of power status or storage activity. 
     Presenting the second information associated with the second mode of operation may comprise providing a visual output that corresponds to the event associated with the second device. Providing the visual output may comprise emitting light, wherein one or more characteristics of the emitted light simulates the processing associated with the event that is performed by the second device. 
     The processing associated with the event performed by the second device may comprise presenting graphical user interface information based on the event. The processing associated with the event performed by the second device may comprise providing an audio output based on the event. 
     The event may include one of loading an application, a file operation, sending of an email message, performing a search in a search engine, wireless network discovery, password entry, a user-initiated task, a system event associated with the second device, or an event associated with an automobile. 
     Other embodiments of this aspect include corresponding systems, apparatus, computer program products, and computer readable media. 
     Particular embodiments of the subject matter described in this specification can be implemented to realize one or more of the following advantages. Information can be communicated to a user using a light-emitting device. A light-emitting device can emit a visually pleasing light effect when particular events or sensory outputs occur. A device with only light-emitting indicator devices can share user interface features with devices that utilize displays for ease of use mnemonics and branding. A light-emitting device can provide at-a-glance information that is less likely to distract a user than detailed information displayed on a display (e.g., when the light-emitting device is used on an automobile dashboard). 
     The details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating an example computer system. 
         FIG. 2  is a block diagram illustrating an example system architecture for communication using a light emission module. 
         FIG. 3  is a flow diagram for an example process for communicating using a light emission module. 
         FIG. 4  illustrates an example intensity versus time graph for a light effect where the triggering event is a user-initiated email transmission. 
         FIGS. 5A-5C  illustrate example intensity versus time graphs for light effects where the triggering event is a data search or a discovery of in-range wireless networks. 
         FIG. 6  illustrates an example graph of volume versus time and an example graph of light intensity versus time. 
         FIGS. 7A-7C  illustrates an example desktop user interface and example intensity graphs of light effects, where the intensities of the light effects simulate the bouncing of an application icon. 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram of a computer system  100  operable to communicate using light effects (e.g., blinking light, a light with varying intensity (i.e., brightness) over time, etc.). In some implementations, the system  100  includes a personal computer (“computer”)  102 . The computer  102  is optionally communicatively coupled to a remote server  107  or other computer system using a network interface  116  and a network  108  (e.g., local area network, wireless network, Internet, intranet, etc.). The computer  102  includes a processor  103  and memory  105 . In some implementations, the computer  102  includes one or more input devices  114  (e.g., keyboard, mouse, buttons, etc.) and one or more output devices  115  (e.g., a display device). A user can interact with the computer system  100  using the input and output devices  114  and  115 , respectively. 
     In some implementations, the computer  102  also includes a local storage device  106  and a graphics module  113  (e.g., graphics card) for storing information and generating graphics for display on a display device, respectively. The local storage device  106  can be a computer-readable medium. The term “computer-readable medium” refers to any medium that includes data and/or participates in providing instructions to a processor for execution, including without limitation, non-volatile media (e.g., optical or magnetic disks), volatile media (e.g., memory) and transmission media. Transmission media includes, without limitation, coaxial cables, copper wire, fiber optics, and computer buses. Transmission media can also take the form of acoustic, light or radio frequency waves. 
     The computer  102  includes one or more light emission modules  117  and optionally a sound module  118 . In some implementations, a light emission module  117  includes one or more light emission devices (e.g., a light-emitting diode (LED)) and associated circuitry for generating various light effects by affecting the emission of light through the LED. The sound module  118  (e.g., a sound card, a sound chip, sound output circuitry) outputs audio to a speaker, headphones, amplifier, or the like (not shown). 
     In some implementations, the light emission module  117  is located on a device that is external to, and coupled to, the computer  102 . For example, the light emission module  117  can be located on a Universal Serial Bus (USB) Flash drive or memory stick, which can be connected to the computer  102  through an interface port (not shown). As another example, the light emission module  117  can be located on a wireless router or access point communicatively coupled to the computer  102 . 
     While communication using light emission is described in this specification with respect to a personal computer  102 , it should be apparent that the disclosed implementations can be incorporated in, or integrated with, any electronic device that has a light emission device, including without limitation, portable and desktop computers, servers, electronics, media players, game devices, mobile phones, smart phones, email devices, personal digital assistants (PDAs), embedded devices, televisions, other consumer electronic devices, set top boxes, storage devices, medical or health devices, on-board systems in automobiles, appliances, etc. In some implementations, the system  100  or electronic device can omit a sound module  118  and/or a display device. 
     One of ordinary skill in the art will recognize that the engines, methods, processes and the like that are described can themselves be an individual process or application, part of an operating system, a plug-in, an application, or the like. In some implementations, the system and methods can be implemented as one or more plug-ins that are installed and run on the personal computer  102 . The plug-ins are configured to interact with an operating system (e.g., MAC OS X, WINDOWS XP, WINDOWS VISTA, LINUX, etc.) and to perform the various functions, as described with respect to  FIGS. 2-6 . A system and method for communication using a light emission module can also be implemented as one or more software applications running on the computer  102  and controlling a light emission module  117 . Such a system and method can be characterized as a framework or model that can be implemented on various platforms and/or networks (e.g., client/server networks, wireless networks, stand-alone computers, portable electronic devices, mobile phones, etc.), and/or embedded or bundled with one or more software applications or the operating system. 
     The computer  102  can store data items, such as files and other data objects, in the local storage device  106 , for example. Examples of data items include documents, images or graphics, video clips, audio clips, and so forth. 
       FIG. 2  is a block diagram illustrating an example system architecture  200  for communication using a light emission module. In some implementations, the system architecture  200  is implemented in a computer  102 . In some implementations, the system architecture  200  includes the processor  103  and one or more light emission modules  117 . 
     In some implementations, the light emission module  117  includes a pulse width modulator  202 , a current regulator  204 , and a light-emitting diode (LED)  206 . The LED  206  can emit light. The current regulator  204  regulates the amount of current supplied to the LED  206 ; the intensity of the light emitted by the LED  206  is based, generally, on the amount of current supplied to the LED  206 . The pulse width modulator  202  receives signals from the processor  103  and modulates the electrical pulses flowing to the current regulator  204 . Thus, the processor controls the emission of light by the LED  206  through the pulse width modulator  202  and the current regulator  204 . An example of using a pulse width modulator to affect the intensity of the light emitted by the LED is disclosed in U.S. Pat. No. 6,658,577, titled “Breathing Status LED Indicator,” issued Dec. 2, 2003, which is incorporated by reference herein in its entirety. 
     The processor  103  controls the light emission module  117 . For example, the processor  103  can control the light emission module  117  to emit a light that can change intensity at different rates or whose intensity remains steady. In some implementations, the processor  103  provides control signals to the light emission module  117  when particular events on the computer  102  are detected and/or when particular visual or audio outputs occur. For example, when a user is attempting to send an email message from the computer  102  (by selecting the send button in an email application) and a sending progress indication (e.g., a progress bar) is displayed on a display device of the computer  102 , the processor  103  can signal the light emission module  117  to emit a light that gradually increases in intensity as the sending progresses until the email is successfully sent, when a light is to be emitted at a steady intensity. 
     In some implementations, the processor  103  signals the light emission module  117  to emit light such that the intensity of the emitted light varies with some event or sensory (e.g., visual, audio) output. In some implementations, intensity values can be predetermined and stored in the local storage  106  or memory  105  for retrieval. For example, the architecture  200  can include one or more look-up tables  210  and/or math and function data  212 . In some implementations, the look-up table  210  and the math/function data  212  are stored in the local storage  106  or memory  105 . The look-up table  210  and the math/function data  212  can be stored in its own dedicated storage or memory, or stored with shared storage or memory with other data. The look-up table  210  can include intensity values for various states in events or visual/audio outputs. The math/function data  212  can include information on one or more mathematical functions that can be used to calculate intensity over time for various events or visual/audio outputs. The processor  103  can use the look-up table  210  and the math/function data  212  to determine a light intensity at a particular time and signal the light emitting module  117  to emit the light at the determined intensity. 
     In some implementations, the architecture  200  includes a timer  208 . The timer  208  can be used to determine elapsed time for the processor  103 . The processor  103  can use the elapsed time to determine the proper intensity for the emitted light. In some implementations, the timer  208  can be integrated into the processor  103 . 
     In some implementations, the processor  103  can include a trigger start signal input  214  and the look-up table  210  and math/function data  212  include inputs for a selection signal  216 . The trigger start signal  214  signals the processor  103  to begin signaling the light emission module  117  to emit light whose intensity follows a function or a set of values. The selection signal  216  selects the look-up table values or function to be used by the processor  103  to determine the proper intensity. 
     In some implementations, the architecture  200  includes multiple light emission modules  117 . The processor  103  can control each of the light emission modules  117  and coordinate the emission of light from the multiple light emission modules  117  in order to emit light patterns and effects using multiple LEDs. 
     In some implementations, the light emission module  117  can be controlled by an external device or respond to inputs from an external device. For example, a computer  102  can control the light emission module of a USB Flash drive connected to the computer  102  through an interface port (e.g., a USB port). 
       FIG. 3  is a flow diagram for an example process  300  for communicating using a light emission module. For convenience, the process  300  will be described in reference to a system (e.g., system  100 ) that performs the process. 
     A light emitting module is operated in normal mode ( 302 ). In normal operation, the light emission module  117  can be used by the system  100  to convey basic information, such as power status and hard drive activity. Alternatively, the light emission module  117  can be dormant until a particular associated activity is initiated. 
     In some implementations, the system  100  includes multiple light emission modules  117 . Each of the light emission modules  117  can be assigned to convey particular information in normal mode. For example, one light emission module can be assigned to be the power on/off indicator, another light emission module can be assigned to be the hard drive activity indicator, and yet another light emission module can be assigned to be the sleep status indicator. 
     A triggering event is detected by the system  100  ( 304 ). A triggering event can be any of a variety of particular events that can occur on the system  100 . A triggering event can be a user event (i.e., an event initiated by a user or an event that occurs in response to a user input) or a system event, for example. Examples of triggering events include changing of compact disks (CD), Digital Versatile Disks (DVD), or other optical disk media in a multi-disk changer; initiation by the user of a task (e.g., system boot-up, initiation of a backup operation, insertion of an optical disk, initiation of a synchronization operation, insertion of a Universal Serial Bus (USB) drive into an interface port, loading an application, a file transfer (e.g., copy, move, synchronization, download, upload), sending of an email message, search in a search engine, wireless network discovery, attempted entry of a password, etc.); the opening of a door of an automobile; shuddering of anti-lock brakes of an automobile; and so on. 
     In some implementations, the triggering event includes an associated sensory output. The sensory output can include a visual output displayed on a display device of the computer  102  (e.g., an on-screen dynamic or animation associated with the triggering event) and/or an audio output (e.g., a sound effect or pattern associated with the triggering event). As used in this specification, an on-screen dynamic is a set of variations or changes in what is displayed on a display device. For example, if the triggering event is a loading of an application by the user clicking on an icon corresponding to the application, the on-screen dynamic can be the icon bouncing up and down. As another example, if the triggering event is a file search, the on-screen dynamic can be a bar swaying back and forth to indicate that the search is ongoing. 
     If a triggering event is not detected ( 304 —No), the light emission module continues to be operated in normal mode. 
     If a triggering event is detected ( 304 —Yes), the normal mode of the light emission module is interrupted ( 306 ) and the light emission module is operated in event mode ( 308 ). While in event mode, the light emission module is operated to emit a light effect that simulates or is otherwise related to the detected triggering event and/or the sensory output (e.g., an on-screen dynamic; a sound effect) associated with the triggering event; the emitted light effect has characteristics (e.g., relative amplitude of intensity, rate of change in intensity, period of oscillation in intensity, etc.) that are similar to characteristics of the triggering event or sensory output. For example, the light effect can change intensity in an oscillating manner with a period that is the same as some oscillatory period of the triggering event or sensory output. The similarity between the characteristics of the light effect and characteristics of the triggering event/sensory output can give a user viewing the light effect hints of what the triggering event or sensory output is, facilitating identification of the triggering event or sensory output by the user. 
     In some implementations, while the triggering event and/or the sensory output are in progress ( 310 —No), the light emission module continues to operate in event mode. When the triggering event and/or the sensory output end ( 310 —Yes), the light emission module is operated in normal mode. Alternatively, the light emission modules can be active for a predetermined amount of time or as long as proscribed by data provided by the system. 
     During event mode, a light emission module  117  is operated to emit a light effect that simulates a sensory output associated with the triggering event or is otherwise related to the triggering event. The light effect includes an emission of light that is emitted with changes in the intensity of the light and other effects (e.g., change in the color of the light). In some implementations, the intensity of the light over time, the rate of change in intensity over time, the color of the light, and other characteristics of the emitted light are patterned to simulate characteristics of the sensory output or the triggering event. For example, if the sensory output or the triggering event involves some sort of oscillation, the intensity of the light effect changes to simulate the oscillation. Thus, while the light emission module  117  operates in event mode, the emitted light can exhibit varying behavior (e.g., changes in intensity or color, blinking, varying speeds of blinking or changes in intensity, etc.) depending on the particular triggering event or sensory output. 
     For example, if the triggering event is the sending of an email, accompanied by a progress bar displayed on a display, the light emission module can begin emitting light when the user hits the send button in the email application. The intensity of the light increases with the progress shown in the progress bar until the sending is completed, when the intensity of the light reaches peak intensity and can remain on for some time (e.g., 3 seconds). As another example, if the triggering event is an incorrect password entered into a password dialog box, accompanied by a jiggle or shaking animation of the password dialog box, the light emission module can emit a light that blinks in a manner that simulates the jiggle/shaking animation. 
     As a further example, on an automobile, a sound effect can be emitted when a door of the automobile is ajar. A light emission module on the automobile can emit a light effect whose intensity simulates the sound effect. 
     In some implementations, the emitted light effect simulates a triggering event that does not have an associated visual output displayed on a display or an audio output from a sound module. For example, an automobile can have an on-board system that monitors the brakes on the automobile and which includes a light emission module  117 . If the brakes shudder, the automobile on-board system detects the shuddering, and the light emission module  117  can be instructed by the automobile on-board system to emit a light effect whose intensity changes with the shuddering. As another example, a light emission module on a wireless router can emit a light effect that simulates the handshaking communication (e.g., data transmissions, the processing between data transmissions, etc.) between a wireless device and the router as the wireless device attempts to gain access to a wireless network through the router. 
     In some implementations, the triggering event and/or sensory output occurs on one device and the light effect simulating the sensory output is emitted from another device. For example, when a USB Flash drive is coupled to the system  100  through a USB port and a file is transferred between the USB drive, the USB drive can emit a light effect that simulates the on-screen dynamic of a progress bar indicating the progress of the transfer. 
       FIG. 4  illustrates an example graph of intensity versus time for a light effect where the triggering event is a user-initiated email transmission. In graph  400 , the intensity begins a monotonic increase when a user-initiated email transmission is detected (e.g., when the user hits a send button in an email application, as illustrated by a selected “send” button  401 A) and a progress bar  401 B is displayed. The progress bar can include multiple segments. In some implementations, the light effect simulates the progress bar; the light increases in intensity with each additional segment displayed in the progress bar, as illustrated by graph segment  402 . 
     When the email transmission is complete (as illustrated by an “email sent” prompt  401 C), the light intensity is steady for a period of time, as illustrated by segment  404 . After the period of time has elapsed, the light emission module can return to normal mode of operation. 
       FIGS. 5A-5C  illustrate example light intensity versus time graphs of light effects where the triggering event is a data search (e.g., a search for files in local storage  106  that match particular criteria) or a discovery of in-range wireless networks. Graph  500  shows intensity versus time with segments  502 ,  506  of fluttering intensity and a segment  504  of zero intensity (i.e., the light is off). Graph  508  shows intensity versus time with segments  510 ,  514  of fluttering intensity and a segment  512  of steady intensity. In some implementations, the fluttering can be based on a mathematical function (e.g., e −t  sin t+1) of time. In some implementations, two fluttering segments in the light effect can be the same (e.g., segments  502  and  506 ) or different (e.g., segments  510 ,  514  flutter about different intensity levels). The segment of steady intensity can be one of zero intensity (e.g., segment  504 ) or a non-zero intensity (e.g., segment  512 ). 
     In some implementations, the fluttering segments can occur during parts of the data search where there is file access activity as a result of performing the search. In some other implementations, the fluttering segments can occur where there is attempted communication with a wireless network as part of the wireless network discovery process. 
     In some other implementations, the intensity versus time graph of the light effect for a data search or network discovery can include segments of different, but steady intensities, as illustrated by graph  516 . The changing intensities can indicate the periods when the data search or the network discovery is in progress. 
     In some implementations, the light effect can simulate an audio output corresponding to the detected triggering event. For example, the relative intensity, rate of change in the intensity, color, etc. of the light emitted by the light emission module can be similar to the amplitude, volume, and/or frequency of the audio output from the sound module.  FIG. 6  illustrates an example graph of volume versus time and an example graph of light intensity versus time. Graph  600  illustrates a graph of volume versus time. Graph  600  includes a segment  602  of monotonically increasing volume and a segment  604  of steady volume. Graph  606  illustrates a graph of intensity versus time in which the rate of change in intensity mimics the rate of change in volume in graph  600 . Graph  606  includes a segment  608  of monotonically increasing intensity and a segment  610  of steady intensity. The intensity increases as the volume increases and remains steady as the volume remains steady. 
     In some implementations, multiple light emission modules can be operated in event mode. When multiple light emission modules are operated in event mode, the emission of light from the individual light emission modules can be coordinated to generate a patterned light effect that simulates or is otherwise related to the triggering event or sensory output in a way that provides hints as to what the event or sensory output is. For example, a computer  102  can have multiple LEDs lined up in a row. When a discovery for in-range wireless networks is initiated, the LEDs can emit light in sequence until the discovery is completed, at which point all of the multiple LEDs are to emit light. For example, if there are 5 LEDs A, B, C, D, and E, the sequence of the LED that is emitting light can be A, then B, then C, then D, then E, then D, then C, then B, then A, then B, and so on. When the network discovery is complete, all five LEDs A, B, C, D, and E are on and emitting light. 
       FIGS. 7A-7C  illustrates an example desktop user interface  700  and an example intensity graph of a light effect, where the intensity of the light simulates the bouncing of an application icon.  FIG. 7A  shows a portion of a desktop user interface  700 . The desktop user interface  700  can include one or more graphical objects or icons  702  corresponding to respective applications. For example, the desktop user interface  700  includes an icon for a web browser application, an icon for an email application, and an icon for a calendar application. When a user selects an icon  702  to load a corresponding application, the icon can be displayed with a bouncing dynamic on a display. For example, when the user selects the calendar application icon  704 , the calendar application icon can bounce up and down, as indicated by the bi-directional arrow  706 . A light effect emitted by the light emission module can simulate the bouncing dynamic, changing intensity with the bounce, as illustrated by intensity graph  708  in  FIG. 7B . The intensity reaches a peak when the icon reaches the peak of the bounce, and the intensity reaches a crest when the icon reaches the crest of the bounce. The intensity continues oscillating between the peak and crest until the bouncing dynamic stops. In some implementations, the maximum height of the icon bounce decreases as time elapses since the selection of the icon. This can be simulated by the light effect that has a damped oscillating intensity, as illustrated by intensity graph  710  in  FIG. 7C . 
     The disclosed and other embodiments and the functional operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by, or to control the operation of, data processing apparatus. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more them. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers. The apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them. A propagated signal is an artificially generated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to suitable receiver apparatus. 
     A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network. 
     The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). 
     Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. However, a computer need not have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. 
     To provide for interaction with a user, the disclosed embodiments can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. 
     The disclosed embodiments can be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of what is disclosed here, or any combination of one or more such back-end, middleware, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet. 
     The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. 
     While this specification contains many specifics, these should not be construed as limitations on the scope of what being claims or of what may be claimed, but rather as descriptions of features specific to particular embodiments. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination. 
     Similarly, while operations are depicted in the drawings in a particular order, this should not be understand as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. 
     Thus, particular embodiments have been described. Other embodiments are within the scope of the following claims.