public long createSession(ApplicationId applicationId, TimeoutBudget timeoutBudget, File applicationDirectory, DeployLogger deployLogger) {
        SessionRepository sessionRepository = getTenant(applicationId).getSessionRepository();
        Session session = sessionRepository.createSessionFromApplicationPackage(applicationDirectory, applicationId, timeoutBudget, deployLogger);
        return session.getSessionId();
    }
Gets the active Session for the given application id.

@return the active session, or null if there is no active session for the given application id.
configserver/src/main/java/com/yahoo/vespa/config/server/ApplicationRepository.java