MessageChannel (PMD Designer 6.16.0 API)

java.lang.Object
- net.sourceforge.pmd.util.fxdesigner.app.MessageChannel<T>

Type Parameters:

T - Type of the messages of this channel
```
public class MessageChannel<T>
extends java.lang.Object
```
Implements some kind of messenger pattern. Conceptually just a globally accessible EventSource with some logging logic.
This patterns allows us to reduce coupling between controllers. The mediator pattern implemented by MainDesignerController was starting to become very obnoxious, every controller had to keep a reference to the main controller, and we had to implement several levels of delegation for deeply nested controllers. Centralising message passing into a few message channels also improves debug logging.
This abstraction is not sufficient to remove the mediator. The missing pieces are the following:
- Global state of the app: that's exposed through Vals on the DesignerRoot
- Transformation requests: that's exposed through an AppServiceDescriptor
Since:

6.12.0

Author:

Clément Fournier

Nested Class Summary

Nested Classes
Modifier and Type Class Description

static class MessageChannel.Message<T>
A message transmitted through a MessageChannel.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`org.reactfx.value.Val<T>`	`latestMessage()`
`org.reactfx.EventStream<T>`	`messageStream(boolean alwaysHandle, ApplicationComponent component)`	Returns a stream of messages to be processed by the given component.
`void`	`pushEvent(ApplicationComponent origin, T content)`	Notifies the listeners of this channel with the given payload.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - messageStream
```
public org.reactfx.EventStream<T> messageStream(boolean alwaysHandle,
                                                ApplicationComponent component)
```
    Returns a stream of messages to be processed by the given component.
    
    Parameters:
    
    component - Component listening to the channel
    
    Returns:
    
    A stream of messages
  - latestMessage
```
public org.reactfx.value.Val<T> latestMessage()
```
  - pushEvent
```
public void pushEvent(ApplicationComponent origin,
                      T content)
```
    Notifies the listeners of this channel with the given payload. In developer mode, all messages are logged. The content may be null.
    
    Parameters:
    
    origin - Origin of the message
    
    content - Message to transmit