Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SERVER-BASED ACTIVE DOCUMENT CONTROL
Field of the Invention
The present invention relates generally to an apparatus and method for
accessing,
changing and displaying an active document in a client/server environment and
more specifically
to an apparatus and method for processing the active document on the server
and displaying the
result of the processing on the client.
Back~Lound of the Invention
Computer communication networks typically include one or more server nodes and
one
or more client nodes. A server node provides a service to a client node upon
receiving a request
from the client. One example of a service is providing to the client node a
web page for display.
An interactive web page can be referred to as an active document. As shown in
FIG. 1,
an active document 10 generally contains at least two portions, a "contents"
portion 3 8 and an
"executable" portion 34. The contents portion of the active document includes
the components
or contents of the web page, such as a string of text 38a, an image 38b, a
table 38c, or a bullet
point 38d. Content components may also include graphics to be displayed as the
document 10 is
viewed or style sheets associated with the active document 10. The executable
portion 34 of the
active document 10 changes the content components associated with the document
10 while the
user is interacting with the active document 10. The executable portion 34 may
include
executable code 34a. The executable portion 34 of the active document 10 may
be provided as
an applet, script or any other form of executable code.
As a simple example, and using the embodiment depicted in FIG. 1, the active
document
10 includes a text component 38a that is initially displayed in black.
Executable code 34a
monitors the position of the cursor on the display and whey. the cursor is
placed over the text
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component 38a, the executable coc a 34a alters the content of the text
component 38a, the color
characteristic, from black to red. T'hi;s changes in the text component 34a
occur in response to
the movement of the cursor over the displayed active document 10.
As depicted in FIG. 2, when a client 18 requests an active document 10, a
server 14
currently sends both the contents portion 38 and the executable portion 34 of
the active document
to the client 18. Document processing, like the simple example given above,
typically occurs
in a browser application 22 executing on the client 18. Because the creator of
the active
document 10 has no control over which browser application 22 will be used to
display the active
document 10, the creator of the active document 10 must contend with issues of
deployment,
10 security, administration and management of the executable portion 34 of the
active document 10.
The existence of many different browser applications 22 creates a need for a
singular, stable
environment in which the executable portion 34 of an active document 10 can be
run that,
nonetheless, allows access by multiple browser applications 22.
The present invention addresses this need.
Summary of the Invention
The invention relates to an apparatus and method for accessing, displaying and
changing an active document in a client/server environment. More specifically,
the invention
relates to executing the executable portion of the active document on the
server, which processes
and manipulates the active document, while displaying the results of the
processing and
manipulating of the active document on a client. Executing the executable code
portion of the
active document on the server ensures that the execution environment is known
and stable. In
such a system, the executable program needs to be tested only once. Also, this
allows the
executable portion of the active document to manipulate the content
independently of any
platform on which the content is displayed. Thus, security and administration
issues are
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minimized. Another advantage of the present invention is that the amount of
code required to be
downloaded to the client is minimized. This helps increase the speed of
transmittal of an active
document and by keeping the executable portion on the server, proprietary code
is not revealed to
the user on the client. Further there are no irreversible deployment decisions
because executable
code (e.g., scripts and applets) which will run on the server also can run on
the client browser
should the need arise. Thus, the present invention allows an active document
to be delivered to a
wide variety of personal computers, Internet appliances, personal digital
assistants, and other
similar client devices.
In one embodiment, the invention relates to a method for providing an active
document to a client over a communication channel, wherein the active document
includes a
contents portion and an executable portion. This method includes the steps of
transmitting over
the communication channel to a client at least a part of the contents portion
of the active
document, generating output data from the executable portion of the active
document and
transmitting over the communication channel to the client the generated output
data to change at
least a part of said transmitted content portion of said active document by
the client. In another
embodiment, the method also includes the step of maintaining said executable
portion of said
active document on a server. In another embodiment, the method also includes
the step of
receiving from the client, prior to the step of transmitting the contents
portion of the active
document, a request identifying the active document. In another embodiment,
the request from
the client includes receiving a Uniform Resource Locator (URL) address
identifying the active
document. In another embodiment the method also includes the steps of
receiving data from the
client and generating, responsive to the received data, output data from the
executable portion of
the active document. In another embodiment the method also includes the step
of changing at
least a part of the content portion of the active document in response to the
received data. In
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another embodiment the method also includes executing the executable portion
of the active
document and changing at least a part of the contents portion of the active
document in response
to the execution of the executable portion of the active document. In another
embodiment the
method also includes the steps of executing a second application that
interacts with the active
document and changing at least a part of the contents portion of the active
document in response
to the execution of the second application.
The invention also relates to a server for providing an active document to a
client over
a communication channel. In one embodiment, the server includes an output data
generator and
a transceiver. The output data generator produces output data in response to
the executable
portion of the active document. The transceiver receives generated output data
for transmission
over the communications channel and the transceiver includes an Application
Program Interface
(API) for manipulating the content portion of the active document. In another
embodiment, the
output data generator produces output data in response to input data received
from the
communications channel. In another embodiment, the server API includes a
Document Object
Model (DOM) API. In another embodiment, the server transceiver transmits
generated output
data over the communications channel.
The invention also relates to a client for receiving over a communications
channel and
displaying an active document. The client includes a browser interface and a
transceiver. The
browser interface is in communication with a browser application. The
transceiver receives data
via the communication channel and transmits received data to the browser
interface.
Brief Description of the Drawings
The invention is pointed out with particularity in the appended claims. The
advantages of
the invention described above, together with further advantages, may be better
understood by
referring to the following description taken in conjunction with the
accompanying drawings. In
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the drawings, like reference characters generally refer to the same parts
throughout the different
views. Also, the drawings are not necessarily to scale, emphasis instead
generally being placed
upon illustrating the principles of the invention.
FIG. 1 is a block diagram of an embodiment of an active document.
FIG. 2 is a block diagram of a process of transmitting an active document from
a
server node to a client node as known in the prior art.
FIG. 3 is a logical diagram of an embodiment of an active document in which an
application-programming interface for manipulating the content components of
the active
document is provided.
FIG. 4 is a block diagram of an embodiment of a system for providing and
displaying
an active document in a client/server environment.
FIG. S is a more detailed block diagram of the embodiment of the invention
shown in
FIG. 4.
FIG. 6 is a state diagram illustrating one embodiment of DAM behavior useful
in
connection with the present invention.
FIG. 7 is a state diagram illustrating one embodiment of DOM Proxy behavior
useful
in connection with the present invention.
FIG. 8 is a screen shot of an embodiment of the invention, depicting in more
detail a
specific example of an interactive web page.
Detailed Description of the Invention
Referring now to FIG. 3, an active document 10 may include many different
content
components 38a, 38b, ..., 38n (referred to generally as the; contents portion
38), and each
component of the contents portion 38 may be created and modified by the
executable portion 34
of the active documents 10. In one embodiment, each cont :nt component 3 8 is
described by a
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Document Object Model (DOM) end the DOM exposes an Application Programming
Interface
(DOM API) 42 to the executable abortion 34. As described in more detail below,
the executable
portion 34 of the active document 10 remains on the server 14 while the
contents portion 38 is
transmitted to the client 18 and thus the DOM API 42 functions are performed
over the
communication channel 30. The DOM API 42 allows the executable portion 34 to
manipulate
content components 38 of the active document 10 in a standard way. Because the
DOM API is
standardized, content components 38 may be manipulated in a standard way
regardless of the
browser application 22 used to display the active document 10.
In broad overview and referring to FIG. 4, a system constructed in accordance
with the
invention permits a user acting on a client computer 18 to communicate with a
server computer
14 over a communication channel 30 (also referred to as a network) to access
an active document
10. In this embodiment, only the content components 38 are transmitted to the
client 18. The
executable portion 34 of the active document 10 is retained on the server 14.
In response to a
user request from the client 18 for the active document 10, the server 14
transmits over the
communication channel 30 the content components 38 of the active document 10
to the client 18.
The contents components 3 8 may be transmitted all together, or each component
may be
transmitted as the browser 22 encounters it, i.e., the components 38 may be
transmitted "on
demand."
The server 14 provides a DOM Proxy 50, which includes a DOM API 42. The
executable portion 34 of the active document 10 issues commands to the DOM
Proxy 50 and
receives output from the DOM Proxy 50 as if it were directly interacting with
the DOM API
provided by the browser application 22. The DOM Proxy 50 may accept more
commands than
the DOM API does. In this embodiment, the DOM Proxy translates additional
commands into
one or more commands the DOM API provides. In some embodiments, the DOM API 42
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provided by the DOM Proxy 50 may be enhanced to provided additional
functionality, or it may
conform to the DOM Level 0 specification or DOM Level 1 specification
promulgated by the
World Wide Web Consortium.
The DOM Proxy 50 receives commands from the executable portion of the active
document 10 and transmits them to the client node 18 via the communication
channel 30. The
DOM Proxy 50 may also receive data from the client 18 over the communications
channel 30
and provide the received data to the executable portion 34 of the active
document 10. The DOM
Proxy 50 may be provided as a servlet or application program. For example, the
DOM Proxy 50
may be provided as a JAVA bean or an Active X control. Alternatively, the DOM
Proxy 50 may
be provided by modifying a browser application 22 to transmit data over the
communications
channel 30 rather than rendering the results of DOM API commands as visual
display.
The client node 18 and the server node 14 can communicate with each other
using a
variety of network connections including standard telephone lines, LAN or WAN
links (e.g., T1,
T3, 56kb, X.25), broad hand connections (ISDN, Frame Relay, ATM), and wireless
connections.
I S Connections can be established using a variety of communication protocols
(e.g., TCP/IP, HTTP,
IPX, SPX, NetBIOS, Ethernet, RS232, and direct asynchronous connections).
The client 18 includes a DOM Access Module (DAM) 46. The DAM 46 communicates
with the DOM Proxy SO over the communications channel 30. The DAM 46 issues
DOM API
calls to the DOM API 42 provided by the browser 22 in response to data
received from the DOM
Proxy 50 over the communications channel 30. The DOM Proxy 50 and the DAM 46
may pack
and unpack data for transfer over the communications channel 30.
Alternatively, the DOM
Proxy 50 and the DAM 46 may enhance a standard protocol or provide their own
protocol for
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transmission of data. The DAM 46 may be provided as a script, applet, plug-in
or application
program. For example, the DAM 46 may be provided as a JAVA bean or an Active X
control.
FIG. 5 depicts the system of FIG. 4 in more detail. In the embodiment shown,
the client
18 executes a browser 22 which establishes an initial connection 30a with web
server software
54 located on the server 14 using the communications channel 30. The browser
22 may be any
appropriate browser application, such as NETSCAPE NAVIGATOR, manufactured by
Netscape
Communications of Mountain View, California or INTERNET EXPLORER manufactured
by
Microsoft Corporation of Redmond, Washington. The server 14 executes any web
server
software 54, such as the APACHE WEB SERVER, an open-source web server
coordinated by
The Apache Foundation of Forest Hill, Maryland or INTERNET INFORMATION SERVER,
manufactured by Microsoft Corporation of Redmond, Washington. The web server
software 54
receives a request for an active document 10 from the client browser 22
executing on the client
14 and retrieves the requested active document 10. The server 14 may retrieve
the active
document 10 from mass storage, such as tape, magnetic disk, optical disk, or
CD-ROM.
I S Alternatively, the server 14 may retrieve the document 10 from memory,
such as RAM or ROM,
or from another server, for example, via a network connection.
Once the browser 22 has established the initial communications between client
18 and
server 14, active document 10 data transfer between client 18 and server 14
occurs through a
second channel 30b. This second channel 30b is a communication channel
established between a
DAM 46 on the client 18 and the DOM Proxy 50 on the server 14. Data transfer
to and from the
active document 10 also occurs through this channel 30b. The DAM 46 and the
DOM Proxy 50
communicate using a protocol that allows individual elements of an active
document to be
identified and represented so that changes in an individual element can be
communicated
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between the DAM 46 and the DOM proxy 50. In some embodiments, a numeric handle
or
"ticket" uniquely identifies each component.
In one embodiment, the protocol used by the DAM 46 and the DOM Proxy 50 allows
the
DOM Proxy 50 to indicate that it should receive notification of certain events
occurring on the
client 18. In these embodiments, the DOM Proxy 50 associates a handler routine
with the ticket
identifying the event in which it has an interest, such as a "MouseClicked"
event. When that
event occurs on the client 18, the DAM 46 notifies the DOM Proxy 50. In
embodiment, the
DAM 46 notifies the DOM Proxy 50 by sending a message to the DOM Proxy
indicating the
event has occurred and includes the ticket and, optionally, a description of
the event. The DOM
Proxy may also indicate that it is no longer interested in an event by sending
a message to the
DAM 46 including the ticket identifying the event. In a particular embodiment,
the DAM 46
responds to such a message with an acknowledgement, allowing the DOM Proxy 50
to release
the binding between the ticket and the handler for the event, e.g., the DOM
Proxy 50 can remove
an entry in a table associating the handler and the event.
1 S FIGs. 6 and 7 depict state machines describing one embodiment of DAM
behavior and
DOM Proxy behavior that implement a protocol useful in connection with the
present invention.
Once the client 18 has made the initial connection with a server 14, the DAM
46 is in an Initial
state 60 and the DOM Proxy 50 is in an Initial state 80. The DAM 46 remains in
the Initial state
60 until an active document 10 identifies an executable portion 34 associated
with a content
component. Once an executable portion 34 is identified, the DAM 46 initiates a
connection with
the DOM Proxy 50 on the server 14 (arrow 62) and enters a Connect Pending
state 64.
In one embodiment, initiation of the connection harrow 62) is accomplished by
sending a
message to the server 14 indicating that a connection is rec; uested. In some
embodiments, the
connect message may include information relating to the requested connection,
such as the active
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document 10 to which the connection request relates, a maximum number of
content components
that may be specified during the cunTuection, the preferred speed at which to
transfer information
relating to content components, and whether to use encryption when transfernng
data.
If the DOM Proxy 50 accepts the connection request, the DAM 46 receives one or
more
messages from the DOM Proxy 50 acknowledging the connection request (arrow 82
of FIG. 7
and arrow 66 of FIG. 6). The DAM 46 transitions to a Connected state 68 and
the DOM Proxy
transitions to a Connected state 84. The acknowledgment messages received from
the DOM
Proxy 50 may include application initialization results, including one or more
commands
instructing the DAM 46 to make changes to one or more content components of
the active
document 10.
If the DOM Proxy 50 rejects the connection request or if the connection fails
for some
other reason, such as physical media failure, absence of a response from the
server 14, server
failure or an explicit signal from the local transport mechanism indicating a
loss of server
responsiveness, the DAIYI 46 returns to the Initial state 60.
While in their respective Connected states 68, 84 the DAM 46 and the DOM Proxy
50
may both initiate synchronous and asynchronous messages. Synchronous messages
require
acknowledgement of completion, while asynchronous messages do not require any
acknowledgement. Table 1 below lists a number of exemplary messages that may
be generated
by a server.
Table 1- Exemplary messages generated by server
Message name (A)sync Data Semantics
Event Done Async - Application has finished
rocessin event
Same Sync Ticket for elementReturn whether element
X X and
Ticket for elementelement Y are the same
Y
element
Get Cookie S c Cookie name Return value of cookie
in a a
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Set_Cookie Async Cookie name Set cookie in page
Cookie value
Expiry date
Applicable path
A licable domain
Remove Cookie Async Cookie name Remove cookie in page
Applicable path
A licable domain
Get Prop Sync Ticket for elementReturn value of element
P ro ert name ro ert
CGet Prop Async Ticket (T) for Store value of element
result
Ticket for elementproperty in ticket cache
against
Pro ert name T
Set Prop Async Ticket for elementSet value of element
property
P roperty name
Pro ert value
Remove Prop Async Ticket for elementRemove element property
Pro ert name
Call Sync Ticket for elementCall element method,
passing
Method name arguments, and return
result
Method ar uments
VCall Async Ticket for elementCall element method,
passing
Method name arguments
Method ar uments
CCall Async Ticket (T) for Call element method,
result passing
Ticket for elementarguments, and store
result in
Method name ticket cache against
T
Method ar uments
Register Async Ticket for elementRegister interest in
events of
Name of event named type occurring
type on the
element; expect 'Event'
messa es from the client
Unregister Async Ticket for elementCease interest in events
of
Name of event named type occurring
type on the
element; expect a symmetric
'Unregister' message
from the
client at some point
in the
future
Forget Async Ticket for elementRemove ticket and element
from ticket cache
Create Async Ticket (T) for Create a non-visual
result element
and store it in ticket
cache
a ainst T
Bind Async Ticket (T) for Lookup element in document
result
Identity of elementusing its (unique) identity
and
store it in ticket cache
against
T
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Schedule Async Ticket for elementArrange to trigger event
'call'
Time period (N) on the element every
N
milliseconds; expect
'Event'
messages from the client
as a
result of this arran
ement
The DOM Proxy 50 may generate a number of asynchronous commands that may be
sent to the
DAM 46 in any order. When transmitting asynchronous commands to the DAM 46,
the DOM
Proxy 50 remains in the Connected state 85 (arrow 86), as does the DAM 46
(arrow 70). When
the DOM Proxy 50 transmits a synchronous event to the DAM 46, the DOM Proxy
enters a
Client Busy state 90 (arrow 88). In this state, the DOM Proxy 50 waits for the
DAM 46 to
respond to the synchronous command. The DOM Proxy 50 returns to the Connected
state 84
upon receipt of a response from the DAM 46 (arrow 92). The DAM remains in the
Connected
state 68 when responding to synchronous messages from the DOM Proxy 50 (arrow
72).
Examples of DAM 46 responses are shown in Table 2 below:
Table 2 - Exemplary messages generated by client
Message name (A)sync Data Semantics
Unregister Async Ticket for elementConfirmation that
no
Name of event more 'Event' messages
type
will be sent for
events
of named type on
element
Result Async Value Result required
by the
server from some
re uest it insti
ated
Event Sync Ticket for elementAn event of the
named
Name of event type has occurred
type on
Event propertiesthe element; expect
an
'EventDone' message
from the server,
preceded by messages
resulting from
it
rocessin the event
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Input from the user that the DOM Proxy 50 has identified as being of interest
is sent from
the browser 22 to the DAM 46 for transmission to the DOM Proxy 50. The DAM 46
transmits a
synchronous event message to the DOM Proxy 50 and transitions to an Event Sent
state 76
(arrow 74). When the DOM Proxy receives the synchronous message from the DAM
46, it
transitions to an Event Received state 96 (arrow 94). While in Event Sent
state 76, the DAM 46
remains able to receive and respond to messages from the DOM Proxy SO as in
its Connected
state 68 (arrows 72', 70'). While in its Event Sent state 76, however, the DAM
46 may not
generate additional event messages and, therefore, the browser 22 will not
respond to user input.
When the DAM 46 transmits a synchronous event message to the DOM Proxy 50, the
DOM Proxy 50 transitions to an Event Received state 96 (arrow 94). In this
state, the DOM
Proxy SO interacts with the executable portion of the active document 10 to
update the active
document 10. Once the active document has been updated with the user input,
the DOM Proxy
50 transmits a message indicating that the event has been processed to the DAM
46 and
transitions to the Connected state 84 (arrow 98). Similarly, the DAM
transitions to its Connected
state 68 (arrow 78).
Data associated with the active document 10 is received by the DOM proxy 50
and
communicated to the executable portion 34 of the active document 10 and/or
other applications
58 residing on the server 14. Similarly, data associated with the active
document 10 destined for
the client 18 is sent to the DOM proxy SO for transmittal.
In one exemplary embodiment, Fig. 8 shows an active document 10 that is a real
estate
web page 100. One feature of this web page is to create a table 120 within the
active document
10 according to the user's selected criteria. This web page l00 displays
several components 104,
108, 112, 116, 120 that would be included as part of the co items portion 38
of the active
document that is sent to the client 18.
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One component is an imag a map of the United Kingdom 104. This is used to
select a
particular county. There are also :;ev-~,ral instances of a check box
component 108 for the user to
identify criteria to be used in the search. There are four instances of a
selection component 112
for the user to select out of a group of items. There are 2 instances of a
text field component 116
for the user to select price. There is a table component 120 and it is empty
when it is initially
sent as part of the contents portion 38 of the active document 10.
The picture component 124 is not initially sent to the client 18 as part of
the contents
portion 38. As stated above, in addition to altering the components of the
contents portion 38,
the executable portion 34 may also add or remove components from the contents
portion 38. The
picture component 124 is an example of a component that is not sent to the
client 18 until there is
some user input.
The executable portion 34 of the web page 100 remains on the server 14. The
executable
portion 34 monitors the user inputs (i.e., monitors the components 104, 108,
112, 116 of the
contents portion 38) and creates the table component 120 in response to those
user selections.
The database of available real estate that is used to select from may be part
of the executable
portion 34 or it may be part of the other applications 58.
The executable portion also alters the other components of the contents
portion 38. For
example, when the cursor is moved over a county in the UK image map 104 and
there is a mouse
click, the executable portion 34 will change the list of towns in the town
selection component
112a to match the selected county. In more detail, to effect this change, the
following steps
occur. The client 18 establishes initial communication with the server 14 over
communication
channel 30, which is the Internet. The browser 22 sends the web server
software 54 the URL
corresponding to the real estate web page 100. The web server software
retrieves the web page
100 (i.e., active document 10) from its storage location. The web page 100 is
defined in
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accordance with the DOM Level 1 specification. The server 14 transmits the
contents portion 38
of the web page 100 to the client 18. The browser 22 accesses the contents
portion 38 of the web
page using the DOM API 42 and displays the web page 100 by displaying each of
the
components 104, 108, 112, 116, 1120 of the contents portion 38.
For data transfer associated with the web page 100, the browser 22 initializes
the DAM
46, if not initialized and establishes a communication channel 30b for data
transfer to and from
the DAM 46. If the client does not have a DAM 46, then one may be downloaded
in several
different ways including with the contents portion 38 of the web page 100. For
data transfer
associated with the web page 100, the web server software 54 initializes the
DOM Proxy 50, if
not initialized and establishes a communication channel 30b for data transfer
to and from the
DOM Proxy 50.
As the user on the client 18 performs a mouse click on one county on the UK
image map
104, this event is captured by the client-based DOM API 42 and sent to the DAM
46. The DAM
46 packs the data representing this event and transmits it to the DOM Proxy 50
according to, for
example, the steps identified in connection with FIG. 6. The DOM Proxy 50
unpacks the data
and transmits it, via the server I4 based DOM API 42 to the executable portion
34. In response
to this event, the executable portion 34 creates a command to alter the town
selection list
component 112a in the contents portion 38 to make the list match the county
selected. The
executable portion retrieves the list of applicable towns. The executable
portion 34 issues a
command to change the selection list component 112a to the retrieved list. The
executable
portion 34 sends this command to the server 14 based DOM API 42. The DOM Proxy
50 packs
the data representing this command and transmits it to the DAM 46. The DAM 46
unpacks the
data and sends the command to the client 18 based DOM API 42. The client-based
DOM API 42
readily understands this command, as it was issued for the server-based DOM
API 42. Beside
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the transmission delay, this creates a seamless operation, even though the
executable portion 34
is executed remotely from the client 18. The client based DOM API 42 then
alters the
component 112a according to the command and the selection list is updated. As
the DOM API is
altering the component 112a in its storage location, the browser modifies the
display accordingly.
The invention may be embodied in other specific forms without departing from
the spirit
or essential characteristics thereof. The foregoing embodiments are therefore
to be considered in
all respects illustrative rather than limiting on the invention described
herein. Scope of the
invention is thus indicated by the appended claims rather than by the
foregoing description, and
all changes that come within the meaning and range of equivalency of the
claims are therefore
intended to be embraced therein.
