Information Technology Reference
In-Depth Information
as output interface to the users. It shows users the representation of the data
from the associated model. A controller is responsible for managing input from
users. It detects users' input events (e.g. key typing or mouse button clicks)
and sends a message to its view for changing the display or for modifying the
date in the corresponding model. In modern GUI toolkits, controllers are often
integrated into view parts (which is called visual objects). There, developers can
assign event handlers to events published by visual objects for defining behaviors
for responding users' inputs.
Model
View
Controller
message
sending
message
sending
P
1
P
2
M
V
C
update
P
2
gimme <slot_name>
set <slot_name><value>
update
P
1
M
V
C
Fig. 2.
Internal component architecture and message exchange between a parent and
the child
2.3 Communication between Parent and Child
For communication between pads, IntelligentPad uses three standard messages:
'set', 'gimme', and 'update' (Fig. 2). In their default definitions, a 'set' message
sends its parameter
<
value
>
to its recipient slot specified by the parameter
<
slot name
>
, whereas a 'gimme' message requests a value from its recipient
slot named by
<
slot name
>
. An 'update' message notifies its state change to its
child pads. Typically, the pad, which works as an input component to its parent,
sends a 'set' message to its parent. When the message brings the state change of
its parent, the parent pad sends 'update' messages to all of its children. Each child
pad that has received an 'update' message sends a 'gimme' message to update
its internal state using the slot value returned by the message. The functional
linkage between pads is achieved by the message passing using above mentioned
three standard messages and the update propagation of internal states according
to the value transferred by the messages. These messages can be enabled or
disabled by each pad.
3 MVC Frameworks in JavaScript
3.1 Problems in JavaScript Development
Mainly, to build a meme media platform, we have to implement functionalities
described in section 2 by coding with JavaScript from scratch. Of course, it
