ClientDelegate

Event handler that receives a notification when the LSClientDelegate instance is removed from a LightstreamerClient through LightstreamerClient.removeDelegate(_:).

This is the last event to be fired on the delegate.

Event handler that receives a notification when the LSClientDelegate instance is added to a LightstreamerClient through LightstreamerClient.addDelegate(_:).

This is the first event to be fired on the delegate.

Event handler that is called when the Server notifies a refusal on the client attempt to open a new connection or the interruption of a streaming connection.

In both cases, the client(_:didChangeStatus:) event handler has already been invoked with a DISCONNECTED status and no recovery attempt has been performed. By setting a custom handler, however, it is possible to override this and perform custom recovery actions.

The error code can be one of the following:

• 1 - user/password check failed

• 2 - requested Adapter Set not available

• 7 - licensed maximum number of sessions reached (this can only happen with some licenses)

• 8 - configured maximum number of sessions reached

• 9 - configured maximum server load reached

• 10 - new sessions temporarily blocked

• 11 - streaming is not available because of Server license restrictions (this can only happen with special licenses).

• 21 - a request for this session has unexpectedly reached a wrong Server instance, which suggests that a routing issue may be in place.

• 30-41 - the current connection or the whole session has been closed by external agents; the possible cause may be:

• The session was closed on the Server side (via software or by the administrator) (32), or through a client “destroy” request (31);

• The Metadata Adapter imposes limits on the overall open sessions for the current user and has requested the closure of the current session upon opening of a new session for the same user on a different browser window (35);

• An unexpected error occurred on the Server while the session was in activity (33, 34);

• An unknown or unexpected cause; any code different from the ones identified in the above cases could be issued. A detailed description for the specific cause is currently not supplied (i.e. errorMessage is nil in this case).

• 60 - this version of the client is not allowed by the current license terms.

• 61 - there was an error in the parsing of the server response thus the client cannot continue with the current session.

• 66 - an unexpected exception was thrown by the Metadata Adapter while authorizing the connection.

• 68 - the Server could not open or continue with the session because of an internal error.

• 71 - this kind of client is not allowed by the current license terms.

• <= 0 - the Metadata Adapter has refused the user connection; the code value is dependent on the specific Metadata Adapter implementation

Event handler that receives a notification each time the LightstreamerClient status has changed.

The status changes may be originated either by custom actions (e.g. by calling LightstreamerClient.disconnect()) or by internal actions. The normal cases are the following:

• After issuing LightstreamerClient.connect(), if the current status is DISCONNECTED*, the client will switch to CONNECTING first and to CONNECTED:STREAM-SENSING as soon as the pre-flight request receives its answer. As soon as the new session is established, it will switch to CONNECTED:WS-STREAMING if the environment permits WebSockets; otherwise it will switch to CONNECTED:HTTP-STREAMING if the environment permits streaming or to CONNECTED:HTTP-POLLING as a last resort. On the other hand if the status is already CONNECTED:* a switch to CONNECTING is usually not needed.

• After issuing LightstreamerClient.disconnect(), the status will switch to DISCONNECTED.

• In case of a server connection refusal, the status may switch from CONNECTING directly to DISCONNECTED. After that, the client(_:didReceiveServerError:withMessage:) event handler will be invoked.

Possible special cases are the following:

• In case of Server unavailability during streaming, the status may switch from CONNECTED:*-STREAMING to STALLED (see ConnectionOptions.stalledTimeout). If the unavailability ceases, the status will switch back to CONNECTED:*-STREAMING; otherwise, if the unavailability persists (see ConnectionOptions.reconnectTimeout), the status will switch to DISCONNECTED:TRYING-RECOVERY and eventually to CONNECTED:*-STREAMING.

• In case the connection or the whole session is forcibly closed by the Server, the status may switch from CONNECTED:*-STREAMING or CONNECTED:*-POLLING directly to DISCONNECTED. After that, the client(_:didReceiveServerError:withMessage:) event handler will be invoked.

• Depending on the setting in ConnectionOptions.slowingEnabled, in case of slow update processing, the status may switch from CONNECTED:WS-STREAMING to CONNECTED:WS-POLLING or from CONNECTED:HTTP-STREAMING to CONNECTED:HTTP-POLLING.

• If the status is CONNECTED:*-POLLING and any problem during an intermediate poll occurs, the status may switch to CONNECTING and eventually to CONNECTED:*-POLLING. The same may hold for the CONNECTED:*-STREAMING case, when a rebind is needed.

• In case a forced transport was set through ConnectionOptions.forcedTransport, only the related final status or statuses are possible.

• In case of connection problems, the status may switch from any value to DISCONNECTED:WILL-RETRY (see ConnectionOptions.retryDelay), then to CONNECTING and a new attempt will start. However, in most cases, the client will try to recover the current session; hence, the DISCONNECTED:TRYING-RECOVERY status will be entered and the recovery attempt will start.

• In case of connection problems during a recovery attempt, the status may stay in DISCONNECTED:TRYING-RECOVERY for long time, while further attempts are made. If the recovery is no longer possible, the current session will be abandoned and the status will switch to DISCONNECTED:WILL-RETRY before the next attempts.

By setting a custom handler it is possible to perform actions related to connection and disconnection occurrences. Note that LightstreamerClient.connect() and LightstreamerClient.disconnect(), as any other method, can be issued directly from within a handler.

The full list of possible new statuses is the following:

• CONNECTING the client has started a connection attempt and is waiting for a Server answer.

• CONNECTED:STREAM-SENSING the client received a first response from the server and is now evaluating if a streaming connection is fully functional.

• CONNECTED:WS-STREAMING a streaming connection over WebSocket has been established.

• CONNECTED:HTTP-STREAMING a streaming connection over HTTP has been established.

• CONNECTED:WS-POLLING a polling connection over WebSocket has been started. Note that, unlike polling over HTTP, in this case only one connection is actually opened (see ConnectionOptions.slowingEnabled).

• CONNECTED:HTTP-POLLING a polling connection over HTTP has been started.

• STALLED a streaming session has been silent for a while, the status will eventually return to its previous CONNECTED:*-STREAMING status or will switch to DISCONNECTED:WILL-RETRY / DISCONNECTED:TRYING-RECOVERY.

• DISCONNECTED:WILL-RETRY a connection or connection attempt has been closed; a new attempt will be performed (possibly after a timeout).

• DISCONNECTED:TRYING-RECOVERY a connection has been closed and the client has started a connection attempt and is waiting for a Server answer; if successful, the underlying session will be kept.

• DISCONNECTED a connection or connection attempt has been closed. The client will not connect anymore until a new LightstreamerClient.connect() call is issued.

Platform limitations: On watchOS the WebSocket transport is not available.

Event handler that receives a notification each time the value of a property of LightstreamerClient.connectionDetails or LightstreamerClient.connectionOptions is changed.

Properties of these objects can be modified by direct calls to them or by server sent events. Possible property names are the following:

• adapterSet

• serverAddress

• user

• password

• serverInstanceAddress

• serverSocketName

• clientIp

• sessionId

• contentLength

• idleTimeout

• keepaliveInterval

• requestedMaxBandwidth

• realMaxBandwidth

• pollingInterval

• reconnectTimeout

• stalledTimeout

• retryDelay

• firstRetryMaxDelay

• slowingEnabled

• forcedTransport

• serverInstanceAddressIgnored

• reverseHeartbeatInterval

• earlyWSOpenEnabled

• HTTPExtraHeaders

• HTTPExtraHeadersOnSessionCreationOnly