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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hypertext apparatus capable of setting
up a plurality of links between nodes. More particularly, the invention
relates to a hypertext apparatus for managing hypertext composed of nodes
that hold information and of link information representing the relations
between the nodes, the apparatus displaying the information from each node
in accordance with the link information.
2. Description of the Related Art
Hypertext apparatuses were first developed as a system capable of holding
information in units called nodes, of displaying character information
held by the nodes, and of linking a plurality of nodes as desired. By
offering such functions, the system structures various units of
information and gains access to reference information.
Recent years have seen the advent of hypertext systems that handle
node-held information (called node information hereinafter) composed of
so-called multimedia information. Multimedia information comprises not
only characters but also monochromatic and color images, sounds and motion
pictures. A number of applications for systems of this kind have been
proposed.
A typical conventional hypertext apparatus is introduced illustratively in
"Hypertext: An Introduction and Survey," Computer, September 1987, IEEE.
Hypertext apparatuses of the above type present the concept of "links" as a
way of defining the relationship between nodes that are the units in which
to hold information. The information representing the links that define
the node-to-node relationship for hypertext apparatuses is provided in two
sets. Illustratively, node A and node B are each referenced in
bidirectional fashion using the two sets of link information. Each node
comprises not only the so-called node information representing the content
of the node but also a plurality of link information items for controlling
the node information. These nodes together with their information
constitute the main part of hypertext and are stored in primary or
secondary storage.
Given the link information constituted as outlined above, a plurality of
nodes may form a tree structure or a network structure that allows the
node information to be displayed in a structured manner. FIGS. 1 and 2 are
views that illustratively describe the concepts of nodes and links for use
with typical hypertext apparatuses. FIG. 1 is an overall conceptual view
of a typical data constitution composed of nodes and links, and FIG. 2 is
a view depicting typical link information held by a node.
In FIG. 1, reference numerals 11, 12, 13 and 14 represent a node each, and
reference numerals 15, 16 and 17 stand for a link each. As illustrated,
this is an example involving four nodes (node A, node B, node C, node D)
among which are established links in a tree structure (link #1, link #2,
link #3).
Link information is held by each node. As shown in FIG. 2, node A 11 has
its link information furnished in a list format data constitution.
Specifically, between a START label 20 and an END label 24 of the data
constitution are first link information 21 (link #1), second link
information 22 (link #2) and third link information 23 (link #3) which
define the linking relations between node A 11 and the other nodes.
In other words, as depicted in FIG. 1, node A 11 has the link information
designating three links (link #1, link #2, link #3) 15, 16 and 17 which
define the relations between node A 11 on the one hand, and node B 12,
node C 13 and node D 14 on the other. The link information of node A 11,
as illustrated in FIG. 2, has pointers arranged in the list format data
constitution connecting the first link information 21 (link #1), second
link information 22 (link #2) and third link information 23 (link #3). The
link information is stored in primary or secondary storage.
In the above example, the access to any of the nodes linked to node A 11
from the latter is executed by following successively the items of link
information from the START label 20 to the END label 24 within the node
11. Each of the link information items (21-23) held in the list format
data constitution designates the corresponding node which may be
referenced as needed. The order in which to reference the nodes is fixedly
determined by the order of the link information items connected by the
list format pointers from the START label 20 to the END label 24.
In the example above, the access from node A 11 is made first to node B 12
then to node C 13 and to node D 14, in the order in which the first link
information 21 (link #1), second link information 22 (link #2) and third
link information 23 (link #3) are read out consecutively. If node A 11 is
to be accessed conversely from node B 12, the link information (not shown)
contained in the node 12 and pointing to node A 11 is utilized for
bidirectional reference.
For hypertext apparatuses that employ the aforementioned data constitution,
adding a new node together with its link information to the existing group
of nodes simply means adding the link information to the end of the
existing link information group arranged in the list format. How this
takes place will now be described in more detail.
FIGS. 3 and 4 are views explaining how a new node E is added to the node A
of FIG. 1. FIG. 3 is an overall conceptual view of the data constitution
of a node group supplemented by a new node, and FIG. 4 is a view showing
typical link information held by the node A when new link information is
added. In this example, as shown in FIG. 3, the new node E 32 along with
its link 33 is added to the data constitution of the node group in FIG. 1.
This updates the link information of the node A, turning the node A into a
node 31. As shown in FIG. 4, the link information held by the node 31
(node A) has new, fourth link information 41 attached to the end of the
third link information 23, the existing last link information.
As indicated, setting an additional link to a node on the hypertext
apparatus simply means adding the new link to the end of the group of link
information items associated with the group of the nodes currently stored
in primary or secondary storage. Heretofore, this scheme has resulted in a
number of disadvantages in connection with the handling and reading of
link information on the conventional hypertext apparatus.
One such disadvantage of the conventional hypertext apparatus is that the
order in which to read link information is determined fixedly by the order
in which the links were generated. The reading order of the link
information cannot be modified as desired. Suppose that in the example of
FIG. 2, the link information of the node A is supplemented by a link #4
with respect to the newly added node E. All that happens in this case is
that, as shown in FIG. 4, the new link information is connected by a
pointer simply to the end of the existing link information group. If the
link information of the node A held in primary or secondary storage is
read by use of a link information reading function such as one offered by
NoteCards, all that is acquired is a list having link #1, link #2, link #3
and link #4 arranged therein in that order, i.e., the existing list simply
supplemented by the new link #4 at its end. The problem here is that after
a new node has been established, it is impossible to set anew the link
information of that node as N-th link information that may be read out as
desired by use of the link information reading function.
It follows that, on the hypertext apparatus, it is necessary to set the
items of link information with their order of display properly established
beforehand. Only this procedure makes it possible to create an application
program that may be displayed on the screen by reading, from primary or
secondary storage and within a predetermined time, the node information
held by the nodes that are linked sequentially starting from a particular
node.
Another disadvantage of the conventional hypertext apparatus is the absence
of means for manipulating the order of link information items that define
the relations between the nodes. For example, the operational function
library offered by NoteCards for use with nodes and links has no means for
putting into a desired order the nodes that are linked starting from a
particular link, or for modifying the established order of the nodes. For
this reason, it is impossible to describe or execute an operational script
that would display, in a user-designated order, the nodes that are linked
from a particular node.
It follows that regarding the application program mentioned above for use
on the hypertext apparatus, the already established order of the links
involved cannot be modified as designated by the user or by program.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to overcome the above
and other deficiencies and disadvantages of the prior art and to provide a
hypertext apparatus for which a plurality of links may be established to
define relations between nodes, the apparatus allowing the order of the
nodes to be established as desired or subsequently modified.
It is another object of the invention to provide a hypertext apparatus for
which a plurality of links may be established to define relations between
nodes, the apparatus managing hypertext composed of the nodes holding
information and of link information defining the relations between the
nodes, so that the information held by each of the nodes may be displayed
in accordance with their link information items arranged into a desired
order.
In carrying out the invention and according to one aspect thereof, there is
provided a hypertext apparatus for managing hypertext composed of nodes
holding information and of link information defining the relations between
the nodes so as to display the information held by each of the nodes in
accordance with the link information, the hypertext apparatus comprising:
node information management means for managing the nodes and for storing
the information held by the nodes; link information management means for
putting into an order the link information defining the relations between
the nodes; link order manipulation means for manipulating the order of the
link information; and display control means for displaying the nodes
successively in accordance with the order of the link information.
In a preferred structure according to the invention, the link information
management means stores individual items of the link information in a data
constitution that may be put into a desired order, and the link order
manipulation means references, adds to, deletes and switches any of the
individual items of the data constitution.
In another preferred structure according to the invention, the hypertext
apparatus further comprises link information browse means for providing a
list format display, on a display screen, of the order of at least a
designated part of the link information managed by the link information
management means.
In a further preferred structure according to the invention, the hypertext
apparatus further comprises user interface means for directly manipulating
the order of the link information displayed on the display screen by the
link information browse means.
In a yet further preferred structure according to the invention, the link
information management means has a storage part for storing the order of
the link information.
According to another aspect of the invention, there is provided a hypertext
apparatus for managing hypertext composed of nodes holding information and
of link information defining the relations between the nodes so as to
display the information held by each of the nodes in accordance with the
link information, the hypertext apparatus comprising: node information
management means for managing the nodes and for storing the information
held by the nodes; link information management means for putting into an
order the link information defining the relations between the nodes; and
link order manipulation means for manipulating the order of the link
information.
In operation, the hypertext apparatus of the invention manages hypertext
composed of nodes holding information and of link information defining the
relations between the nodes, and displays the information held by each of
the nodes in accordance with the link information. In this setup, the node
information management means manages the nodes and stores the information
held by the nodes. The link information management means puts into an
order the link information defining the relations between the nodes. When
the link order manipulation means manipulates the order of the link
information illustratively by adding to, deleting or switching it, the
display control means displays the nodes successively in accordance with
the manipulated order of the link information.
In this manner, where the hypertext has a plurality of links established
between the nodes, these links may be arranged into a desired order that
may be manipulated as needed. The hypertext, composed of the nodes holding
information and of link information defining the relations between the
nodes, has the link information put into a desired order so that the
information held by each of the nodes may be displayed successively
according to the link information thus ordered.
The link information management means gives a particular order to the link
information for management purposes by storing the individual items of
that information in a data constitution that may be put into the desired
order. The link order manipulation means, for its part, manipulates the
order of the link information by referencing, adding to, deleting and
switching any of the individual items of the data constitution. The order
of the link information is thus easy to manipulate as desired.
The link information browse means that may be preferably furnished provides
a list format display, on the display screen, of the order of at least a
designated part of the link information managed by the link information
management means in connection with the manipulation of the link
information order. At this point, the user interface means is used to
manipulate directly the order of the link information displayed in list
format on the display screen by the link information browse means. This
allows the user to manipulate, easily on the screen, the order of the link
information defining the relations between the nodes.
As outlined, the link information that defines the relations between the
nodes may be arranged into a desired order for management purposes. With
the order of the link information established, it is easy to reference,
add, delete or switch the N-th link information item within the link
information order. The user or program may readily designate and
manipulate any node linked to a particular node. This makes it possible to
build with ease an application program illustratively causing the display
of the nodes to be switched in a specific order and at predetermined
intervals.
These and other objects, features and advantages of the invention will
become more apparent upon a reading of the following description and
appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an overall conceptual view of a typical data constitution
composed of nodes and links for use with a typical hypertext apparatus;
FIG. 2 is a view depicting typical link information held by a node;
FIG. 3 is an overall conceptual view of the data constitution of a node
group being supplemented by a new node;
FIG. 4 is a view showing typical link information held by the node A when
new link information is added;
FIG. 5 is a block diagram of major component parts constituting a hypertext
apparatus practiced as a preferred embodiment of the invention;
FIG. 6 is a view showing members of a node information structure held by a
node information management part of the embodiment;
FIG. 7 is a view depicting slots in a link information structure managed by
a link information management part of the embodiment;
FIG. 8 is a view of a typical user interface screen display given by an
application program running on the embodiment;
FIG. 9 is a conceptual view of typical nodes and links and the relations in
effect therebetween when the order of link information is changed;
FIG. 10 is a schematic view of a data constitution in which the hypertext
data of the nodes and links in FIG. 9 is stored in the node information
management part and link information management part of the embodiment;
FIG. 11 is a flowchart of steps in which the embodiment displays the
contents of nodes in accordance with the order of their links; and
FIG. 12 is a flowchart of steps in which the embodiment inserts a node into
a group of nodes.
DESCRIPTION OF THE PREFERRED EMBODIMENT
One preferred embodiment of the invention will now be described with
reference to the accompanying drawings. FIG. 5 is a block diagram of major
component parts constituting a hypertext apparatus practiced as the
preferred embodiment of the invention. In FIG. 5, reference numeral 1 is
an interface control part; 2 is an input control part; 3 is a program
execution part; 4 is a display control part; 5 is a node information
management part; 6 is a link information management part; 7 is a link
order manipulation part; and 8 is a link information entity management
part. Nodes serve as the units of such information as text information,
image information, sound information and motion pictures. Links form a
data constitution which describes the relations between nodes and which
may be interpreted by the program or by the system. In other words, links
make up an object comprising a set of mutually related nodes.
The embodiment of FIG. 5 includes processing elements for managing nodes
and for putting into an order the link information defining the relations
between the nodes, in addition to the processing elements which are
intrinsic to hypertext apparatuses and which retain the node information
of the hypertext. The interface control part 1 controls the user interface
associated with the nodes and links of the hypertext, and notifies the
program execution part 3 of an event whose occurrence may be detected by
the input control part 2. The interface control part 1 causes the display
control part 4 to display the information entities of nodes in a window on
a display.
The input control part 2 notifies the interface control part 1 of a user
operation event acquired from such input devices as a keyboard and a
mouse. Under the directions of the interface control part 1, the program
execution part 3 tells the node information management part 5, link
information management part 6 and link order manipulation part 7
respectively to generate a node, to generate a link and to manipulate the
link order. The display control part 4, under control of the interface
control part 1, displays information in the designated display area.
The node information management part 5 manages a plurality of node
information structures holding the information about each node. The link
information management part 6 manages a plurality of link information
structures defining the relations between the nodes. The link order
manipulation part 7 changes the order of a plurality of link information
structures 10 referenced by the node information management part 5 under
the directions of the program execution part 3. The node information
entity management part 8 manages such node information as character
strings, images, motion pictures and sounds stored illustratively in
primary or secondary storage. The node information is referenced from each
node as entity information.
FIG. 6 is a view showing members of a node information structure held by
the node information management part 5. As shown in FIG. 6, the members
making up the node information structure 9 held by the node information
management part 5 (see FIG. 5) reside in a node identifier slot 61, a
display procedure slot 62, an entity information pointer slot 63 and a
link information slot 64. The node identifier slot 61 is used to identify
uniquely this node information structure within the system. The display
procedure slot 62 retains the pointer pointing to a procedure program
function used when the node in question is to be displayed on the screen.
The entity information pointer slot 63 retains the pointer pointing to the
entity information to be displayed by the node in question. The entity
information thus pointed to may be a character string, image information,
motion pictures or sounds. The link information slot 64 retains, in a list
format data constitution, the pointer pointing to the link information
structure for holding the link information attached to the node in
question.
FIG. 7 is a view depicting slots in the link information structure managed
by the link information management part 6. As shown in FIG. 7, the slots
making up the link information structure 10 managed by the link
information management part 6 (see FIG. 5) comprise a link identifier slot
71, a from-link slot 72 and a to-link slot 73. The link identifier slot 71
is used to identify uniquely this link information structure within the
system. The from-link slot 72 retains the pointer pointing to the node
information structure of, say, the node A when a link is set
illustratively to link the node A to the node B. The to-link slot 73
retains the pointer pointing to the node information structure of the node
B when, as in the example above, a link is set to link the node A to the
node B.
How the embodiment of the invention works will now be described
illustratively using a case in which the order of links between nodes is
manipulated. FIG. 8 is a view of a typical user interface screen display
provided by an application program running on the embodiment. As depicted
in FIG. 8, the interface control part 1 and display control part 4 (see
FIG. 5) act to open a window 80 in which to display the node A. The window
80 is made up of a node content display area 81, an operation designating
area 82 and an order display area 83.
The user interface of the embodiment is implemented by use of the three
areas in the window 80. In the window 80, the node content display area 81
displays the entity information of the node group linked in a particular
order starting from the current node. The operation designating area 82
displays screen buttons 84 (PLAY, INS, DEL). The PLAY button is used to
designate a display of nodes according to their order; the INS button,
when used, designates insertion of a node; the DEL button is used to
delete a node. The user interface function allows any of these buttons to
be designated as desired. The order display area 83 displays, in a
left-justified manner and according to the link information order, icons
85 representing each of the nodes linked starting from the current node.
The icons 85 show in a list format the links connected to the current node
and the order in which these links are established.
In the window of the node A in FIG. 8, the icons representing the node B,
node C and node D appear left-justified. The link information of the node
A indicates that the node A is linked to the nodes B, C and D, in that
order. If the order of the icons 85 shown left-justified in the order
display area 83 is changed, the order of the link information items set in
the node A is also changed accordingly.
For example, a mouse may be operated (in conjunction with a graphical user
interface function) to switch the icon positions of the nodes B and C
(i.e., node C placed to the left of node B) in the left-justified order.
This operation changes accordingly the order of the link information
specific to the node A.
FIG. 9 is a conceptual view of typical nodes and links and the relations in
effect therebetween when the order of link information is changed. Shown
in FIG. 9 is the state in which three nodes B, C and D are linked to the
node A by way of the link information "link #2," "link #1" and "link #3,"
respectively. In this case, the link information "link #2" is followed by
"link #1" and "link #3," in that order from left to right.
Suppose that the PLAY button is clicked with the mouse in the operation
designating area 82 of the window 80 of the node A, in order to designate
the display of node contents in the order specific to the node A. In that
case, the node information of the nodes linked successively according to
the link information of the node A is displayed. Specifically, the content
of the node A is displayed first followed by the contents of the nodes C,
B and D, in that order, inside the node content display area 81 of the
window 80.
These nodes and the linked data constitution thereof will now be described.
FIG. 10 is a schematic view of a typical data constitution in which the
hypertext data of the nodes and links in FIG. 9 is stored in the node
information management part and link information management part of the
embodiment. As explained above, the node A is linked to the node C, node B
and node D, in that order. This means that the link information in the
node information structure of the node A is held as "link #1, link #2,
link #3" in a link information order storage of the link information
management part; the state of the links and their order are thereby set in
the link information order storage.
FIG. 11 is a flowchart of steps in which the embodiment displays the
contents of nodes in accordance with the order of their links. This
processing is started using the mouse to click the "PLAY" button in the
operation designating area 82 of the window 80 in FIG. 8. The contents of
the linked nodes are displayed in the order set by the link information.
In step 101, the input control part 2 detects an operation of the "PLAY"
button effected with the mouse (i.e., mouse event) in the operation
designating area 82. The detected event is reported to the interface
control part 1. Step 102 identifies the node A displayed in the display
screen position where the mouse was operated. The node A is set as the
currently processed node after the node information structure of the node
A is acquired from the node information management part 5.
In step 103, the link information of the node information structure is
acquired from the currently processed node A and is set in a variable
"LINKLIST." In step 104, values are set on a loop counter. That is, the
count variable "N" is initialized to 1, and the final value variable "MAX"
is set to the number of elements in the variable "LINKLIST."
In step 105, various items of the node information start to be displayed
consecutively. First, the link order manipulation part 7 searches for and
retrieves the N-th link information structure based on the link
information established in the variable "LINKLIST," and sets the retrieved
link information structure in a variable "LINK-N." If the link information
is furnished illustratively in a list format data constitution, the
processing above of search and retrieval is implemented by use of, say,
the NTH function for LISP processing systems.
In step 106, that link information structure in the variable "LINK-N" which
was retrieved and set in the preceding step 105 is referenced. The pointer
to the next node information structure pointed to by the pointer in the
to-link slot of the link information structure is set in a variable
"NODE-N." This provides information pointing to the N-th node whose
content is to be displayed next. Step 107 accesses and reads the entity
information linked by the entity information pointer of the node
information structure designated by the pointer pointing to the acquired
node. When the entity information (character string, image, sounds, motion
pictures) is acquired from the node information entity management part 8,
the content of the acquired information is reproduced and displayed in the
node content display area 81 of the window 80 by applying the program
which is associated with the pointer in the display procedure slot 62 of
the node information structure 9.
In step 108, the variable "N" of the loop counter is updated. Specifically,
the count variable "N" is incremented by 1. In step 109, the count
variable "N" of the loop counter is compared with its final value variable
"MAX." If the value "N" is equal to or greater than the value "MAX"
(N>MAX), the processing is terminated. If the result of the comparison is
other than N>MAX, step 105 is reached again. In step 105, the next node
information is reproduced in accordance with the next link information.
The processing above is carried out so that the node C is displayed
followed by node B and node D, in accordance with the order of the link
information.
Described below is how to insert a node E immediately after the node C in
the setup of FIG. 9. FIG. 12 is a flowchart of steps depicting how the
embodiment illustratively inserts a node into a group of nodes. This
processing is started using the mouse to click the "INS" button in the
operation designating area 82 of the window 80 in FIG. 8.
In step 201, the interface control part 1 detects via the input control
part 2 an operation of the "INS" button effected with the mouse (a mouse
event) in the operation designating area 82. This causes the display
control part 4 to display illustratively an insertable node candidate menu
indicating that the insertion processing has started. In step 202, the
user selects the node candidate for insertion from the insertable node
candidate menu. The node information structure (i.e., node candidate for
insertion) associated with the selected node is substituted in a variable
"INS-NODE." It is assumed in this example that the node E is selected for
insertion.
In step 203, the user designates the position into which to insert the
selected node E. This initiates the search for and the detection of the
N-th node position in which to insert the node E. The detected position is
set in the variable "N." Step 204 reads the link information of the node
information structure associated with the currently processed node A which
is displayed in the node content display area of the window. The link
information thus read out is set in the variable "LINKLIST."
In step 205, a request is made for the link information management part 6
to generate a new link information structure. This step is needed to
create a new link between the currently processed node A and the node
candidate for insertion (node E). The link information structure generated
anew is stored in a variable "LINKSTR."
In step 206, the pointer to the node information structure of the currently
processed node A is placed into the from-link slot of the link information
structure stored in the variable "LINKSTR." The pointer to the node
information structure associated with the insertion node candidate (node
E) and held in the variable "INS-NODE" is placed into the to-link slot of
the link information structure stored in the variable "LINKSTR."
In step 207, the link order manipulation part 7 inserts the link
information structure held in the variable "LINKSTR" into the N-th
position in the link information structure list of the link information in
the variable "LINKLIST." In step 208, the link information slot in the
node information structure of the node A is replaced with the content of
the variable "LINKLIST" containing the new link information structure.
This completes the insertion processing.
The steps described allow the new node (node E in the example above) to be
linked to the node A in the order designated by the user. With this
accomplished, the PLAY operation described with reference to the flowchart
of FIG. 11 may be performed on the node A, and the node E will then be
displayed as the N-th node.
As described, the hypertext apparatus of the invention offers a user
interface capable of putting into a desired order the links between the
nodes to be managed and of manipulating the established link order. This
makes it easy to create illustratively an application program allowing the
display of node contents to be switched in a desired order and at
predetermined intervals on the hypertext apparatus. It is also possible to
build with ease a system for arranging information that emphasizes
temporal relations between nodes (e.g., chronological tables).
As many apparently different embodiments of this invention may be made
without departing from the spirit and scope thereof, it is to be
understood that the invention is not limited to the specific embodiments
thereof except as defined in the appended claims.
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