Data-Access Object (DAO) interfaces used by the BPEL Service Provider to communicate with the data store; can be used to customize the BPEL persistence layer. The BPEL DAO layer is used to maintain persistent state of each active BPEL process instance. This includes the values of scope variables, as well as instance "state snapshots" that may need to be persisted due to the activation of receive, pick, or invoke activity that cannot be immediately satisfied. Like the DAO of the framework (see {@link com.fs.jlo.sfwk.bapi.dao}), the BPEL DAO is a "dumb" object-relational model supporting transactional access.