Web Client 8.0.8

MpnSubscriptionListener

MpnSubscriptionListener

Interface to be implemented to receive MpnSubscription events including subscription/unsubscription, triggering and status change.

Constructor

new MpnSubscriptionListener()

This is a dummy constructor not to be used in any case.

Methods

onListenEnd(subscription)

Event handler called when the MpnSubscriptionListener instance is removed from an MpnSubscription through MpnSubscription#removeListener.
This is the last event to be fired on the listener.

Parameters:
Name Type Description
subscription MpnSubscription

The MpnSubscription this instance was removed from.

onListenStart(subscription)

Event handler called when the MpnSubscriptionListener instance is added to an MpnSubscription through MpnSubscription#addListener.
This is the first event to be fired on the listener.

Parameters:
Name Type Description
subscription MpnSubscription

The MpnSubscription this instance was added to.

onPropertyChanged(propertyName)

Event handler called each time the value of a property of MpnSubscription is changed.
Properties can be modified by direct calls to their setter or by server sent events. A property may be changed by a server sent event when the MPN subscription is modified, or when two MPN subscriptions coalesce (see LightstreamerClient#subscribeMpn).

Parameters:
Name Type Description
propertyName String

The name of the changed property. It can be one of the following:

  • mode
  • group
  • schema
  • adapter
  • notification_format
  • trigger
  • requested_buffer_size
  • requested_max_frequency
  • status_timestamp

onStatusChanged(status, timestamp)

Event handler called when the server notifies that an MpnSubscription changed its status.
Note that in some server clustering configurations the status change for the MPN subscription's trigger event may not be called. The corresponding push notification is always sent, though.

Parameters:
Name Type Description
status String

The new status of the MPN subscription. It can be one of the following:

  • UNKNOWN
  • ACTIVE
  • SUBSCRIBED
  • TRIGGERED
timestamp Number

The server-side timestamp of the new subscription status.
See:

onSubscription()

Event handler called when an MpnSubscription has been successfully subscribed to on the server's MPN Module.
This event handler is always called before other events related to the same subscription.
Note that this event can be called multiple times in the life of an MpnSubscription instance only in case it is subscribed multiple times through LightstreamerClient#unsubscribeMpn and LightstreamerClient#subscribeMpn. Two consecutive calls to this method are not possible, as before a second onSubscription() event an MpnSubscriptionListener#onUnsubscription event is always fired.

onSubscriptionError(code, message)

Event handler called when the server notifies an error while subscribing to an MpnSubscription.
By implementing this method it is possible to perform recovery actions.

Parameters:
Name Type Description
code Number

The error code sent by the Server. It can be one of the following:

  • 17 - bad Data Adapter name or default Data Adapter not defined for the current Adapter Set.
  • 21 - bad Group name.
  • 22 - bad Group name for this Schema.
  • 23 - bad Schema name.
  • 24 - mode not allowed for an Item.
  • 30 - subscriptions are not allowed by the current license terms (for special licenses only).
  • 40 - the MPN Module is disabled, either by configuration or by license restrictions.
  • 41 - the request failed because of some internal resource error (e.g. database connection, timeout, etc.).
  • 43 - invalid or unknown application ID.
  • 44 - invalid syntax in trigger expression.
  • 45 - invalid or unknown MPN device ID.
  • 46 - invalid or unknown MPN subscription ID (for MPN subscription modifications).
  • 47 - invalid argument name in notification format or trigger expression.
  • 48 - MPN device suspended.
  • 49 - one or more subscription properties exceed maximum size.
  • 50 - no items or fields have been specified.
  • 52 - the notification format is not a valid JSON structure.
  • 53 - the notification format is empty.
  • 66 - an unexpected exception was thrown by the Metadata Adapter while authorizing the connection.
  • 68 - the Server could not fulfill the request because of an internal error.
  • <= 0 - the Metadata Adapter has refused the subscription request; the code value is dependent on the specific Metadata Adapter implementation.
message String

The description of the error sent by the Server; it can be null.

onTriggered()

Event handler called when the server notifies that an MpnSubscription did trigger.
For this event to be called the MpnSubscription must have a trigger expression set and it must have been evaluated to true at least once.
Note that this event can be called multiple times in the life of an MpnSubscription instance only in case it is subscribed multiple times through LightstreamerClient#unsubscribeMpn and LightstreamerClient#subscribeMpn. Two consecutive calls to this method are not possible.
Note also that in some server clustering configurations this event may not be called. The corresponding push notification is always sent, though.

See:

onUnsubscription()

Event handler called when an MpnSubscription has been successfully unsubscribed from on the server's MPN Module.
After this call no more events can be received until a new MpnSubscriptionListener#onSubscription event.
Note that this event can be called multiple times in the life of an MpnSubscription instance only in case it is subscribed multiple times through LightstreamerClient#unsubscribeMpn and LightstreamerClient#subscribeMpn. Two consecutive calls to this method are not possible, as before a second onUnsubscription() event an MpnSubscriptionListener#onSubscription event is always fired.

onUnsubscriptionError(code, message)

Event handler called when the server notifies an error while unsubscribing from an MpnSubscription.
By implementing this method it is possible to perform recovery actions.

Parameters:
Name Type Description
code Number

The error code sent by the Server. It can be one of the following:

  • 30 - subscriptions are not allowed by the current license terms (for special licenses only).
  • 40 - the MPN Module is disabled, either by configuration or by license restrictions.
  • 41 - the request failed because of some internal resource error (e.g. database connection, timeout, etc.).
  • 43 - invalid or unknown application ID.
  • 45 - invalid or unknown MPN device ID.
  • 46 - invalid or unknown MPN subscription ID.
  • 48 - MPN device suspended.
  • 66 - an unexpected exception was thrown by the Metadata Adapter while authorizing the connection.
  • 68 - the Server could not fulfill the request because of an internal error.
  • <= 0 - the Metadata Adapter has refused the unsubscription request; the code value is dependent on the specific Metadata Adapter implementation.
message String

The description of the error sent by the Server; it can be null.