Controlling message delivery in publish/subscribe messaging

A computer program product comprising a computer readable storage device including computer readable program code, where the computer readable program code when executed on a computer causes the computer to:

• determine, in response to publication of a topic message on a topic to a messaging system by a publisher application, whether any subscriber applications are registered for the topic;
• deliver, in response to determining that at least one subscriber application is registered for the topic, the published topic message to each registered subscriber application;
• and
• in response to determining that no subscriber applications are registered for the topic:
• store the published topic message;
• deliver, in response to receipt of a first subsequent subscription request from a new subscriber application for the topic, the stored published topic message to the new subscriber application;
• deliver the stored published topic message to any other new subscriber applications that register for the topic within a first predetermined time of the first subsequent subscription request prior to discarding the stored published topic message, where the first predetermined time is configurable to zero to allow configuration of stored message delivery only to subscriber applications that register for the topic simultaneously with the new subscriber application;
• and
• discard the stored published topic message if no subscriber application registers for the topic within a second predetermined time of publication of the topic message on the topic.

A messaging system, comprising:

• a buffer store in a memory;
• and
• a processor programmed to:
• determine, in response to publication of a topic message on a topic to the messaging system by a publisher application, whether any subscriber applications are registered for the topic;
• deliver, in response to determining that at least one subscriber application is registered for the topic, the published topic message to each registered subscriber application;
• and
• in response to determining that no subscriber applications are registered for the topic:
• store the published topic message in the buffer store;
• deliver, in response to receipt of a first subsequent subscription request from a new subscriber application for the topic, the stored published topic message to the new subscriber application;
• deliver the stored published topic message to any other new subscriber applications that register for the topic within a first predetermined time of the first subsequent subscription request prior to discarding the stored published topic message, where the first predetermined time is configurable to zero to allow configuration of stored message delivery only to subscriber applications that register for the topic simultaneously with the new subscriber application;
• and
• discard the stored published topic message if no subscriber application registers for the topic within a second predetermined time of publication of the topic message on the topic.