WADI - WADI Application Distribution Infrastructure

WADI is an acronym of 'WADI Application Distribution Infrastructure'.

WADI started life as a solution to the problems surrounding the distribution of state in clustered web tiers. It has evolved into a more generalised distributed state and service framework.

WADI's aim is to resolve many of the problems of dealing with state in a cluster. This involves technologies such as:

WADI Core:

  • Vertically - a distributed 'space' with pluggable/stackable paging and persistance mechanisms (e.g. File and Database)
  • Horizontally - A scalable, highly available, self-partitioning, self-healing clustering substrate
  • Providing transparent migration of State to Invocation but also migration of Invocation to State
  • Pluggable in-memory replication strategies for HA state


  • An AOP extension providing the fine-grained replication of state, i.e. object instances. Thanks to AOP, field updates and method executions are tracked and replayed on state replicas.


  • A resolution to application vs container space concurrency issues surrounding HttpSessions
  • Pluggable HttpSession serialisation strategies - per-session, per-attribute
  • HttpRequest relocation (by redirection and proxying)
  • HttpSession replication

WADI currently supports the following J2EE containers and application servers:

  • Jetty-6.x
  • Geronimo-2.x/Jetty
  • Geronimo-2.1+/Tomcat
  • Geronimo-2.1+/OpenEJB

If you have problems or concerns with WADI, ask on the users mailing list .