Some articles on oltp:

Online Transaction Processing - Requirements
... In large applications, efficient OLTP may depend on sophisticated transaction management software (such as CICS) and/or database optimization tactics to facilitate the processing of large numbers of concurrent ... For even more demanding decentralized database systems, OLTP brokering programs can distribute transaction processing among multiple computers on a network ... OLTP is often integrated into service-oriented architecture (SOA) and Web services ...