Methods, systems, and computer program products that provide for a runtime
messaging infrastructure, which abstracts send and receive operations for
exchanging messages with partner endpoint. The messaging infrastructure
improves availability and scalability of a message application by
improving on the availability and scalability of the underlying message
transports. In particular, availability and scalability are improved by
linking the message application at runtime with any number of the message
transports, without the message application specifying a transport at
development time. The message infrastructure receives instructions from
the message application specifying end-to-end delivery assurances. The
infrastructure uses transports in order to fulfill the specified delivery
assurance, and creates a link between the message application and
transports for use in exchanging messages. Session state storage can be
maintained in a pluggable store, which could be, for example, a durable
database store or an application memory store.