Diffusion JavaScript API 6.1.7

Class: Subscription

Subscription

new Subscription()

Deprecated

As of 6.0, this class is deprecated. Use Subscription#asType instead. In future versions, Session#stream will return a ValueStream.

Provides an untyped stream of topic events.

Properties:
Name Type Description
selector String

The selector this subscription was created for
Deprecated:
  • Yes
Fires:
  • Subscription#event:open
  • Subscription#event:close
  • Subscription#event:update
  • Subscription#event:subscribe
  • Subscription#event:unsubscribe
  • Subscription#event:error

Extends

Methods

asType(datatype)

Produce a ValueStream from this subscription stream, in order to receive values as a particular DataType. The ValueStream will only receive values from topics that are of matching type for the provided data type.

The lifecycle of the produced ValueStream is independent of this subscription. If this subscription was created using Session#stream without a selector (i.e as a fallback stream), the ValueStream will also be registered as a fallback stream.

Parameters:
Name Type Description
datatype DataType

The data type to produce a stream for.
Returns:

A new ValueStream for the provided data type

Type
ValueStream
Example
// Produce a value stream for receiving JSON values.
var datatype = diffusion.datatypes.json();

session.stream('foo').asType(datatype).on('value', function(topic, value) {
    //...
});

close()

Close the subscription. No further events will be emitted. This operation is purely client-side; the server will still maintain any active subscriptions for this client.

Overrides:

off(event [, listener])

Remove a listener from a specified event.

Parameters:
Name Type Argument Description
event String

The event to remove listeners from
listener function <optional>

The listener to remove. All listeners for the event are removed if this is not specified
Inherited From:
Returns:

This stream.

Type
Stream
Examples
// Bind a single listener to the 'foo' event and then deregister it
var listener = function() {};
stream.on('foo', listener);
stream.off('foo', listener);
// Bind a listener to the 'foo' event and deregister all listeners
var listener = function() {};
stream.on('foo', listener);
stream.off('foo');

on(events [, listener])

Register listeners against events.

A single listener may be bound to an event by passing the event name and listener function.

Multiple listeners may be bound by passing in an object, mapping event names to listener functions.

Parameters:
Name Type Argument Description
events String | Object

The event name or object mapping event names to listeners
listener function <optional>

The listener to bind to the event, if passed as string.
Inherited From:
Returns:

This stream.

Type
Stream
Examples
// Bind a single listener to the 'foo' event
stream.on('foo', function(arg1, arg2) {
    console.log("Called for 'foo' event", arg1, arg2);
});
// Bind multiple listeners
stream.on({
    foo : function() { ... },
    bar : function() { ... },
    baz : function() { ... }
});

transform(transformer)

Deprecated

As of 6.0, this is deprecated. Use Subscription#asType instead.

Create a new Subscription instance that is bound with a transformation function.

Parameters:
Name Type Description
transformer function

The transformation function to apply to updates
Returns:

The new subscription bound with the transformation

Type
Subscription