This chapter introduces data cartridges in Oracle Event Processing. Data cartridges extend Oracle Continuous Query Language (Oracle CQL) to support domain-specific abstract data types of the following forms: simple types, complex types, array types, and domain-specific functions.
This chapter includes the following sections:
The Oracle CQL data cartridge framework allows you to tightly integrate arbitrary domain data types and functions with the Oracle CQL language, allowing the usage of these extensions within Oracle CQL queries in the same way you use Oracle CQL native types and built-in functions.
With regards to data types, the framework supports both simple and complex types, the latter allowing the usage of object-oriented programming.
Using Oracle CQL data cartridges, you can extend the Oracle CQL engine with domain-specific types that augment and interoperate with native Oracle CQL built-in types.
Each data cartridge is identified by a unique data cartridge name that defines a name space for the data cartridge implementation. You use the data cartridge name to disambiguate references to types, methods, fields, and constructors, if necessary (see link::=).
Depending on the data cartridge implementation, you may be able to define an application context that the Oracle Event Processing server propagates to the functions and types that an instance of the data cartridge provides.
For example, you might be able to configure an Oracle Event Processing server resource or a default data cartridge option and associate this application context information with a particular data cartridge instance.
For more information, see "Understanding Data Cartridge Application Context" in the Oracle Fusion Middleware Developer's Guide for Oracle Event Processing for Eclipse.
How you access data cartridge types, methods, fields, and constructors using Oracle CQL is the same for all data cartridge implementations.
You may reference a data-cartridge function by using the
func_expr, which may optionally take a link name.
To reference the members of a complex type, Oracle CQL provides the
For more information, see:
What you access is, of course, unique to each data cartridge implementation. For more information, see:
To simplify Oracle data cartridge type names, you can use aliases as Section 2.7.2, "Defining Aliases Using the Aliases Element" describes.