Disclosed are a system comprising a computer-readable storage medium storing at least one program, and a computer-implemented method for event messaging over a network. A subscription interface receives data indicative of a subscription request for sessionized data. An allocation module allocates a sessionizer bank linked to the subscription request. A messaging interface module provisions identifiers linked to the respective processing engines of the sessionizer bank. The messaging interface module registers the allocated sessionizer bank as available to process event messages matching the subscription request by providing the provisioned identifiers. The messaging interface module receives event messages from a producer device linked by a collection server to a selected one of the processing engines of the sessionizer bank. The selected one of the processing engine processes the received event messages in accordance with session rule data linked to the subscription request to generate sessionized data.