For example, a loan processing application will send messages through MOM to credit bureaus and other systems as it gathers information to complete the processing of the loan. MOM offers a measure of recoverability through the queuing mechanism, which can be journaled, and it allows queues to be restored in the event of a failure. An ORB is middleware that allows applications to send objects and request services in an object-oriented system. The ORB keeps track of information about each object and the actual addresses of all the objects in the system, and it is able to route requests in the right form to the specific object. The application requests the object by name without knowing where the object resides.
ORBs currently are synchronous although initiatives are underway to develop asynchronous ORBs.
Examples of ORBs include Iona Orbix, Visigenic VisiBroker, and BEA ObjectBroker. SQL-oriented database access middleware connects applications with databases over the network and translates generic SQL requests into the database s native SQL or other database language. SQL-oriented middleware is a mature segment dominated by the database vendors themselves and established companies with multidatabase access middleware. The connection is synchronous, but scalability can be a serious issue with both the middleware and database becoming a performance choke point. Oracle Connect, Intersolv s DataDirect, and JDBC are examples of SQL-oriented middleware.