5.6. Using other input sources

Files and databases are the main data sources used as input for batch processes, but they aren’t the only ones. You may want to reuse services provided by existing applications or integrate with an information system with asynchronous and event-driven features. Spring Batch provides implementations of the ItemReader interface for such cases, which this section examines.

5.6.1. Services as input

Reusability of existing services is a key concept of modern applications. This avoids reinventing the wheel, provides robustness, and saves time. Batch processes can integrate in existing systems that already provide entities to read data. These sources can be POJOs that implement business services; data access objects; or more complex entities managed by a container, such as EJB3 or by services accessible with lightweight protocols provided by Caucho, such as Hessian and Burlap. Figure 5.12 describes different patterns for batch processes to read data from existing entities.