class ConnectionOptions

package com.lightstreamer.client

Used by LightstreamerClient to provide an extra connection properties data object.

Data object that contains the policy settings used to connect to a Lightstreamer Server.
An instance of this class is attached to every LightstreamerClient as LightstreamerClient.connectionOptions

See also:

Methods

getContentLength():Long

Inquiry method that gets the length expressed in bytes to be used by the Server for the response body on a HTTP stream connection.

Returns:

The length to be used by the Server for the response body on a HTTP stream connection

See also:

setContentLength(contentLength:Long):Void

Setter method that sets the length in bytes to be used by the Server for the response body on a stream connection (a minimum length, however, is ensured by the server). After the content length exhaustion, the connection will be closed and a new bind connection will be automatically reopened.
NOTE that this setting only applies to the "HTTP-STREAMING" case (i.e. not to WebSockets).

Parameters:

contentLength

The length to be used by the Server for the response body on a HTTP stream connection.

Throws:

IllegalArgumentException

if a negative or zero value is configured

getFirstRetryMaxDelay():Long

Inquiry method that gets the maximum time to wait before trying a new connection to the Server in case the previous one is unexpectedly closed while correctly working.

Returns:

The max time (in milliseconds) to wait before trying a new connection.

See also:

setFirstRetryMaxDelay(firstRetryMaxDelay:Long):Void

Setter method that sets the maximum time to wait before trying a new connection to the Server in case the previous one is unexpectedly closed while correctly working. The new connection may be either the opening of a new session or an attempt to recovery the current session, depending on the kind of interruption.
The actual delay is a randomized value between 0 and this value. This randomization might help avoid a load spike on the cluster due to simultaneous reconnections, should one of the active servers be stopped. Note that this delay is only applied before the first reconnection: should such reconnection fail, only the setting of this.setRetryDelay will be applied.

Parameters:

firstRetryMaxDelay

The max time (in milliseconds) to wait before trying a new connection.

Throws:

IllegalArgumentException

if a negative or zero value is configured

getForcedTransport():Null<String>

Inquiry method that gets the value of the forced transport (if any).

Returns:

The forced transport or null

See also:

setForcedTransport(forcedTransport:Null<String>):Void

Setter method that can be used to disable/enable the Stream-Sense algorithm and to force the client to use a fixed transport or a fixed combination of a transport and a connection type. When a combination is specified the Stream-Sense algorithm is completely disabled.
The method can be used to switch between streaming and polling connection types and between HTTP and WebSocket transports.
In some cases, the requested status may not be reached, because of connection or environment problems. In that case the client will continuously attempt to reach the configured status.
Note that if the Stream-Sense algorithm is disabled, the client may still enter the "CONNECTED:STREAM-SENSING" status; however, in that case, if it eventually finds out that streaming is not possible, no recovery will be tried.

Parameters:

forcedTransport

can be one of the following:

  • null: the Stream-Sense algorithm is enabled and the client will automatically connect using the most appropriate transport and connection type among those made possible by the environment.
  • "WS": the Stream-Sense algorithm is enabled as in the null case but the client will only use WebSocket based connections. If a connection over WebSocket is not possible because of the environment the client will not connect at all.
  • "HTTP": the Stream-Sense algorithm is enabled as in the null case but the client will only use HTTP based connections. If a connection over HTTP is not possible because of the environment the client will not connect at all.
  • "WS-STREAMING": the Stream-Sense algorithm is disabled and the client will only connect on Streaming over WebSocket. If Streaming over WebSocket is not possible because of the environment the client will not connect at all.
  • "HTTP-STREAMING": the Stream-Sense algorithm is disabled and the client will only connect on Streaming over HTTP. If Streaming over HTTP is not possible because of the environment the client will not connect at all.
  • "WS-POLLING": the Stream-Sense algorithm is disabled and the client will only connect on Polling over WebSocket. If Polling over WebSocket is not possible because of the environment the client will not connect at all.
  • "HTTP-POLLING": the Stream-Sense algorithm is disabled and the client will only connect on Polling over HTTP. If Polling over HTTP is not possible because of the environment the client will not connect at all.

Throws:

IllegalArgumentException

if the given value is not in the list of the admitted ones.

getHttpExtraHeaders():Null<NativeStringMap<String>>

Inquiry method that gets the Map object containing the extra headers to be sent to the server.

Returns:

The Map object containing the extra headers to be sent

See also:

setHttpExtraHeaders(httpExtraHeaders:Null<NativeStringMap<String>>):Void

Setter method that enables/disables the setting of extra HTTP headers to all the request performed to the Lightstreamer server by the client.
Note that the Content-Type header is reserved by the client library itself, while other headers might be refused by the environment and others might cause the connection to the server to fail.
For instance, you cannot use this method to specify custom cookies to be sent to Lightstreamer Server; leverage LightstreamerClient.addCookies instead. The use of custom headers might also cause the client to send an OPTIONS request to the server before opening the actual connection.

Parameters:

httpExtraHeaders

a Map object containing header-name header-value pairs. Null can be specified to avoid extra headers to be sent.

getIdleTimeout():Long

Inquiry method that gets the maximum time the Server is allowed to wait for any data to be sent in response to a polling request, if none has accumulated at request time. The wait time used by the Server, however, may be different, because of server side restrictions.

Returns:

The time (in milliseconds) the Server is allowed to wait for data to send upon polling requests.

See also:

setIdleTimeout(idleTimeout:Long):Void

Setter method that sets the maximum time the Server is allowed to wait for any data to be sent in response to a polling request, if none has accumulated at request time. Setting this time to a nonzero value and the polling interval to zero leads to an "asynchronous polling" behavior, which, on low data rates, is very similar to the streaming case. Setting this time to zero and the polling interval to a nonzero value, on the other hand, leads to a classical "synchronous polling".
Note that the Server may, in some cases, delay the answer for more than the supplied time, to protect itself against a high polling rate or because of bandwidth restrictions. Also, the Server may impose an upper limit on the wait time, in order to be able to check for client-side connection drops.

Parameters:

idleTimeout

The time (in milliseconds) the Server is allowed to wait for data to send upon polling requests.

Throws:

IllegalArgumentException

if a negative value is configured

getKeepaliveInterval():Long

Inquiry method that gets the interval between two keepalive packets sent by Lightstreamer Server on a stream connection when no actual data is being transmitted. If the returned value is 0, it means that the interval is to be decided by the Server upon the next connection.

lifecycle If the value has just been set and a connection to Lightstreamer Server has not been established yet, the returned value is the time that is being requested to the Server. Afterwards, the returned value is the time used by the Server, that may be different, because of Server side constraints.

Returns:

The time, expressed in milliseconds, between two keepalive packets sent by the Server, or 0.

See also:

setKeepaliveInterval(keepaliveInterval:Long):Void

Setter method that sets the interval between two keepalive packets to be sent by Lightstreamer Server on a stream connection when no actual data is being transmitted. The Server may, however, impose a lower limit on the keepalive interval, in order to protect itself. Also, the Server may impose an upper limit on the keepalive interval, in order to be able to check for client-side connection drops. If 0 is specified, the interval will be decided by the Server.

Parameters:

keepaliveInterval

the keepalive interval time (in milliseconds) to set, or 0.

Throws:

IllegalArgumentException

if a negative value is configured

See also:

getRequestedMaxBandwidth():String

Inquiry method that gets the maximum bandwidth that can be consumed for the data coming from Lightstreamer Server, as requested for this session. The maximum bandwidth limit really applied by the Server on the session is provided by this.getRealMaxBandwidth()

Returns:

A decimal number, which represents the maximum bandwidth requested for the streaming or polling connection expressed in kbps (kilobits/sec), or the string "unlimited".

See also:

setRequestedMaxBandwidth(maxBandwidth:String):Void

Setter method that sets the maximum bandwidth expressed in kilobits/s that can be consumed for the data coming from Lightstreamer Server. A limit on bandwidth may already be posed by the Metadata Adapter, but the client can furtherly restrict this limit. The limit applies to the bytes received in each streaming or polling connection.

general_edition_note Bandwidth Control is an optional feature, available depending on Edition and License Type. To know what features are enabled by your license, please see the License tab of the Monitoring Dashboard (by default, available at /dashboard).

Parameters:

maxBandwidth

A decimal number, which represents the maximum bandwidth requested for the streaming or polling connection expressed in kbps (kilobits/sec). The string "unlimited" is also allowed, to mean that the maximum bandwidth can be entirely decided on the Server side (the check is case insensitive).

Throws:

IllegalArgumentException

if a negative, zero, or a not-number value (excluding special values) is passed.

See also:

getRealMaxBandwidth():Null<String>

Inquiry method that gets the maximum bandwidth that can be consumed for the data coming from Lightstreamer Server. This is the actual maximum bandwidth, in contrast with the requested maximum bandwidth, returned by this.getRequestedMaxBandwidth().
The value may differ from the requested one because of restrictions operated on the server side, or because bandwidth management is not supported (in this case it is always "unlimited"), but also because of number rounding.

lifecycle If a connection to Lightstreamer Server is not currently active, null is returned; soon after the connection is established, the value becomes available, as notified by a call to ClientListener.onPropertyChange with argument "realMaxBandwidth".

Returns:

A decimal number, which represents the maximum bandwidth applied by the Server for the streaming or polling connection expressed in kbps (kilobits/sec), or the string "unlimited", or null.

See also:

getPollingInterval():Long

Inquiry method that gets the polling interval used for polling connections.
If the value has just been set and a polling request to Lightstreamer Server has not been performed yet, the returned value is the polling interval that is being requested to the Server. Afterwards, the returned value is the the time between subsequent polling requests that is really allowed by the Server, that may be different, because of Server side constraints.

Returns:

The time (in milliseconds) between subsequent polling requests.

See also:

setPollingInterval(pollingInterval:Long):Void

Setter method that sets the polling interval used for polling connections. The client switches from the default streaming mode to polling mode when the client network infrastructure does not allow streaming. Also, polling mode can be forced by calling this.setForcedTransport with "WS-POLLING" or "HTTP-POLLING" as parameter.
The polling interval affects the rate at which polling requests are issued. It is the time between the start of a polling request and the start of the next request. However, if the polling interval expires before the first polling request has returned, then the second polling request is delayed. This may happen, for instance, when the Server delays the answer because of the idle timeout setting. In any case, the polling interval allows for setting an upper limit on the polling frequency.
The Server does not impose a lower limit on the client polling interval. However, in some cases, it may protect itself against a high polling rate by delaying its answer. Network limitations and configured bandwidth limits may also lower the polling rate, despite of the client polling interval.
The Server may, however, impose an upper limit on the polling interval, in order to be able to promptly detect terminated polling request sequences and discard related session information.

Parameters:

pollingInterval

The time (in milliseconds) between subsequent polling requests. Zero is a legal value too, meaning that the client will issue a new polling request as soon as a previous one has returned.

Throws:

IllegalArgumentException

if a negative value is configured

getReconnectTimeout():Long

Inquiry method that gets the time the client, after entering "STALLED" status, is allowed to keep waiting for a keepalive packet or any data on a stream connection, before disconnecting and trying to reconnect to the Server.

Returns:

The idle time (in milliseconds) admitted in "STALLED" status before trying to reconnect to the Server.

See also:

setReconnectTimeout(reconnectTimeout:Long):Void

Setter method that sets the time the client, after entering "STALLED" status, is allowed to keep waiting for a keepalive packet or any data on a stream connection, before disconnecting and trying to reconnect to the Server. The new connection may be either the opening of a new session or an attempt to recovery the current session, depending on the kind of interruption.

Parameters:

reconnectTimeout

The idle time (in milliseconds) allowed in "STALLED" status before trying to reconnect to the Server.

Throws:

IllegalArgumentException

if a negative or zero value is configured

See also:

getRetryDelay():Long

Inquiry method that gets the minimum time to wait before trying a new connection to the Server in case the previous one failed for any reason, which is also the maximum time to wait for a response to a request before dropping the connection and trying with a different approach. Note that the delay is calculated from the moment the effort to create a connection is made, not from the moment the failure is detected or the connection timeout expires.

Returns:

The time (in milliseconds) to wait before trying a new connection.

See also:

setRetryDelay(retryDelay:Long):Void

Setter method that sets

  1. the minimum time to wait before trying a new connection to the Server in case the previous one failed for any reason; and
  2. the maximum time to wait for a response to a request before dropping the connection and trying with a different approach.

Enforcing a delay between reconnections prevents strict loops of connection attempts when these attempts always fail immediately because of some persisting issue. This applies both to reconnections aimed at opening a new session and to reconnections aimed at attempting a recovery of the current session.
Note that the delay is calculated from the moment the effort to create a connection is made, not from the moment the failure is detected. As a consequence, when a working connection is interrupted, this timeout is usually already consumed and the new attempt can be immediate (except that ConnectionOptions.setFirstRetryMaxDelay will apply in this case). As another consequence, when a connection attempt gets no answer and times out, the new attempt will be immediate.

As a timeout on unresponsive connections, it is applied in these cases:
  • Streaming: Applied on any attempt to setup the streaming connection. If after the timeout no data has arrived on the stream connection, the client may automatically switch transport or may resort to a polling connection.
  • Polling and pre-flight requests: Applied on every connection. If after the timeout no data has arrived on the polling connection, the entire connection process restarts from scratch.

This setting imposes only a minimum delay. In order to avoid network congestion, the library may use a longer delay if the issue preventing the establishment of a session persists.

Parameters:

retryDelay

The time (in milliseconds) to wait before trying a new connection.

Throws:

IllegalArgumentException

if a negative or zero value is configured

See also:

getReverseHeartbeatInterval():Long

Inquiry method that gets the reverse-heartbeat interval expressed in milliseconds. A 0 value is possible, meaning that the mechanism is disabled.

Returns:

The reverse-heartbeat interval, or 0.

See also:

setReverseHeartbeatInterval(reverseHeartbeatInterval:Long):Void

Setter method that enables/disables the reverse-heartbeat mechanism by setting the heartbeat interval. If the given value (expressed in milliseconds) equals 0 then the reverse-heartbeat mechanism will be disabled; otherwise if the given value is greater than 0 the mechanism will be enabled with the specified interval.
When the mechanism is active, the client will ensure that there is at most the specified interval between a control request and the following one, by sending empty control requests (the "reverse heartbeats") if necessary.
This can serve various purposes:

  • Preventing the communication infrastructure from closing an inactive socket that is ready for reuse for more HTTP control requests, to avoid connection reestablishment overhead. However it is not guaranteed that the connection will be kept open, as the underlying TCP implementation may open a new socket each time a HTTP request needs to be sent.
    Note that this will be done only when a session is in place.
  • Allowing the Server to detect when a streaming connection or Websocket is interrupted but not closed. In these cases, the client eventually closes the connection, but the Server cannot see that (the connection remains "half-open") and just keeps trying to write. This is done by notifying the timeout to the Server upon each streaming request. For long polling, the this.setIdleTimeout setting has a similar function.
  • Allowing the Server to detect cases in which the client has closed a connection in HTTP streaming, but the socket is kept open by some intermediate node, which keeps consuming the response. This is also done by notifying the timeout to the Server upon each streaming request, whereas, for long polling, the this.setIdleTimeout setting has a similar function.

Parameters:

reverseHeartbeatInterval

the interval, expressed in milliseconds, between subsequent reverse-heartbeats, or 0.

Throws:

IllegalArgumentException

if a negative value is configured

getSessionRecoveryTimeout():Long

Inquiry method that gets the maximum time allowed for attempts to recover the current session upon an interruption, after which a new session will be created. A 0 value also means that any attempt to recover the current session is prevented in the first place.

Returns:

The maximum time allowed for recovery attempts, possibly 0.

See also:

setSessionRecoveryTimeout(sessionRecoveryTimeout:Long):Void

Setter method that sets the maximum time allowed for attempts to recover the current session upon an interruption, after which a new session will be created. If the given value (expressed in milliseconds) equals 0, then any attempt to recover the current session will be prevented in the first place.
In fact, in an attempt to recover the current session, the client will periodically try to access the Server at the address related with the current session. In some cases, this timeout, by enforcing a fresh connection attempt, may prevent an infinite sequence of unsuccessful attempts to access the Server.
Note that, when the Server is reached, the recovery may fail due to a Server side timeout on the retention of the session and the updates sent. In that case, a new session will be created anyway. A setting smaller than the Server timeouts may prevent such useless failures, but, if too small, it may also prevent successful recovery in some cases.

Parameters:

sessionRecoveryTimeout

The maximum time allowed for recovery attempts, expressed in milliseconds, including 0.

Throws:

IllegalArgumentException

if a negative value is passed.

getStalledTimeout():Long

Inquiry method that gets the extra time the client can wait when an expected keepalive packet has not been received on a stream connection (and no actual data has arrived), before entering the "STALLED" status.

Returns:

The idle time (in milliseconds) admitted before entering the "STALLED" status.

See also:

setStalledTimeout(stalledTimeout:Long):Void

Setter method that sets the extra time the client is allowed to wait when an expected keepalive packet has not been received on a stream connection (and no actual data has arrived), before entering the "STALLED" status.

Parameters:

stalledTimeout

The idle time (in milliseconds) allowed before entering the "STALLED" status.

Throws:

IllegalArgumentException

if a negative or zero value is configured

See also:

isHttpExtraHeadersOnSessionCreationOnly():Bool

Inquiry method that checks if the restriction on the forwarding of the configured extra http headers applies or not.

Returns:

the httpExtraHeadersOnSessionCreationOnly

See also:

setHttpExtraHeadersOnSessionCreationOnly(httpExtraHeadersOnSessionCreationOnly:Bool):Void

Setter method that enables/disables a restriction on the forwarding of the extra http headers specified through this.setHttpExtraHeaders(Map). If true, said headers will only be sent during the session creation process (and thus will still be available to the metadata adapter notifyUser method) but will not be sent on following requests. On the contrary, when set to true, the specified extra headers will be sent to the server on every request.

Parameters:

httpExtraHeadersOnSessionCreationOnly

true/false to enable/disable the restriction on extra headers forwarding.

isServerInstanceAddressIgnored():Bool

Inquiry method that checks if the client is going to ignore the server instance address that will possibly be sent by the server.

Returns:

Whether or not to ignore the server instance address sent by the server.

See also:

setServerInstanceAddressIgnored(serverInstanceAddressIgnored:Bool):Void

Setter method that can be used to disable/enable the automatic handling of server instance address that may be returned by the Lightstreamer server during session creation.
In fact, when a Server cluster is in place, the Server address specified through ConnectionDetails.setServerAddress(String) can identify various Server instances; in order to ensure that all requests related to a session are issued to the same Server instance, the Server can answer to the session opening request by providing an address which uniquely identifies its own instance.
Setting this value to true permits to ignore that address and to always connect through the address supplied in setServerAddress. This may be needed in a test environment, if the Server address specified is actually a local address to a specific Server instance in the cluster.

general_edition_note Server Clustering is an optional feature, available depending on Edition and License Type. To know what features are enabled by your license, please see the License tab of the Monitoring Dashboard (by default, available at /dashboard).

Parameters:

serverInstanceAddressIgnored

true or false, to ignore or not the server instance address sent by the server.

See also:

isSlowingEnabled():Bool

Inquiry method that checks if the slowing algorithm is enabled or not.

Returns:

Whether the slowing algorithm is enabled or not.

See also:

setSlowingEnabled(slowingEnabled:Bool):Void

Setter method that turns on or off the slowing algorithm. This heuristic algorithm tries to detect when the client CPU is not able to keep the pace of the events sent by the Server on a streaming connection. In that case, an automatic transition to polling is performed.
In polling, the client handles all the data before issuing the next poll, hence a slow client would just delay the polls, while the Server accumulates and merges the events and ensures that no obsolete data is sent.
Only in very slow clients, the next polling request may be so much delayed that the Server disposes the session first, because of its protection timeouts. In this case, a request for a fresh session will be reissued by the client and this may happen in cycle.

Parameters:

slowingEnabled

true or false, to enable or disable the heuristic algorithm that lowers the item update frequency.

setProxy(proxy:Null<Proxy>):Void

Setter method that configures the coordinates to a proxy server to be used to connect to the Lightstreamer Server.

Parameters:

proxy

The proxy configuration. Specify null to avoid using a proxy.