A minor update for SObjectizer-5.5.19 has been released with some important improvements:

• It is possible to check the presence of a subscription for an agent. It could be used in cases where a subscription is made by request and there could be repeated requests. See so-5.5.19 Checking the Presense of a Subscription for more details and examples.
• Format for so_drop_subscription methods fixed. This format has no changes from very old versions of SObjectizer-5 and do not support for event-handler with non-void return types. Now so_drop_subscription support modern event-handler formats.
• Methods has_subscription and drop_subscription have been added to state_t class. It means that state_t can be used not only for subscription but also for other subscription-related tasks.