This version is still in development and is not considered stable yet. For the latest stable version, please use Spring Integration 6.4.1!

SFTP Session Caching

Starting with Spring Integration version 3.0, sessions are no longer cached by default. The cache-sessions attribute is no longer supported on endpoints. If you wish to cache sessions, you must use a CachingSessionFactory (see the next example).

In versions prior to 3.0, the sessions were automatically cached by default. A cache-sessions attribute was available for disabling the auto caching, but that solution did not provide a way to configure other session-caching attributes. For example, you could not limit on the number of sessions created. To support that requirement and other configuration options, we added a CachingSessionFactory. It provides sessionCacheSize and sessionWaitTimeout properties. As its name suggests, the sessionCacheSize property controls how many active sessions the factory maintains in its cache (the default is unbounded). If the sessionCacheSize threshold has been reached, any attempt to acquire another session blocks until either one of the cached sessions becomes available or until the wait time for a session expires (the default wait time is Integer.MAX_VALUE). The sessionWaitTimeout property enables configuration of the wait time.

If you want your sessions to be cached, configure your default session factory (as described earlier) and then wrap it in an instance of CachingSessionFactory where you may provide those additional properties. The following example shows how to do so:

<bean id="sftpSessionFactory"
    class="org.springframework.integration.sftp.session.DefaultSftpSessionFactory">
    <property name="host" value="localhost"/>
</bean>

<bean id="cachingSessionFactory"
    class="org.springframework.integration.file.remote.session.CachingSessionFactory">
    <constructor-arg ref="sftpSessionFactory"/>
    <constructor-arg value="10"/>
    <property name="sessionWaitTimeout" value="1000"/>
</bean>

The preceding example creates a CachingSessionFactory with its sessionCacheSize set to 10 and its sessionWaitTimeout set to one second (1000 milliseconds).

Starting with Spring Integration version 3.0, the CachingConnectionFactory provides a resetCache() method. When invoked, all idle sessions are immediately closed and in-use sessions are closed when they are returned to the cache. When using isSharedSession=true, the channel is closed and the shared session is closed only when the last channel is closed. New requests for sessions establish new sessions as necessary.

Starting with version 5.1, the CachingSessionFactory has a new property testSession. When true, the session will be tested by performing a REALPATH command for an empty path to ensure it is still active; if not, it will be removed from the cache; a new session is created if no active sessions are in the cache.