com.hazelcast.cp.session

## Interface CPSession

-     public interface CPSession

  Represents a CP session.

  For CP data structures that are doing ownership management of the resources, such as lock or semaphore, a session is required to keep track of the liveliness of the caller. In this context, caller means an entity that uses the CPI subsystem APIs. It can be either a Hazelcast server or client. A caller initially creates a session before sending its very first session-based request to the CP group, such as a lock / semaphore acquire. After creating a session on the CP group, the caller stores its session id locally and sends it alongside its session-based operations. A single session is used for all lock and semaphore proxies of the caller. When a CP group receives a session-based operation, it checks the validity of the session using the session id information available in the operation. A session is valid if it is still open in the CP group. An operation with a valid session id is accepted as a new session heartbeat. While a caller is idle, in other words, it does not send any session-based operation to the CP group for a while, it commits periodic heartbeats to the CP group in the background in order to keep its session alive. This interval is specified in `CPSubsystemConfig.getSessionHeartbeatIntervalSeconds()`.

  A session is closed when the caller does not touch the session during a predefined duration. In this case, the caller is assumed to be crashed and all its resources are released automatically. This duration is specified in `CPSubsystemConfig.getSessionTimeToLiveSeconds()`. Please check `CPSubsystemConfig` to learn the recommendations for choosing a reasonable session time-to-live duration.

  Sessions offer a trade-off between liveliness and safety. If a very small value is set to `CPSubsystemConfig.setSessionTimeToLiveSeconds(int)`, then a session owner could be considered crashed very quickly and its resources can be released prematurely. On the other hand, if a large value is set, a session could be kept alive for an unnecessarily long duration even if its owner actually crashes.

  See Also:
    `CPSubsystemConfig`

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Interface and Description
    --- | ---
    `static class` | `CPSession.CPSessionOwnerType` Represents type of endpoints that create CP sessions

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `long` | `creationTime()` Returns the timestamp of when the session was created
    `Address` | `endpoint()` Returns the endpoint that has created this session
    `String` | `endpointName()` Returns name of the endpoint that has created this session
    `CPSession.CPSessionOwnerType` | `endpointType()` Returns type of the endpoint that has created this session
    `long` | `expirationTime()` Returns the timestamp of when the session will expire
    `long` | `id()` Returns id of the session
    `boolean` | `isExpired(long timestamp)` Returns true if the session expires before the given timestamp.
    `long` | `version()` Returns version of the session.

- - ### Method Detail

    - #### id

          long id()

      Returns id of the session

    - #### creationTime

          long creationTime()

      Returns the timestamp of when the session was created

    - #### expirationTime

          long expirationTime()

      Returns the timestamp of when the session will expire

    - #### version

          long version()

      Returns version of the session. A session's version is incremented on each heartbeat.

    - #### isExpired

          boolean isExpired(long timestamp)

      Returns true if the session expires before the given timestamp.

    - #### endpoint

          Address endpoint()

      Returns the endpoint that has created this session

    - #### endpointType

          CPSession.CPSessionOwnerType endpointType()

      Returns type of the endpoint that has created this session

    - #### endpointName

          String endpointName()

      Returns name of the endpoint that has created this session

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