4.4.3 Using the FML Buffer Type
FML (Field Manipulation Language) is a flexible data structure that can be used as a typed buffer. The FML data structure stores tagged values that are typed, variable in length, and may have multiple occurrences. The typed buffer is treated as an abstract data type in FML.
FML gives you the ability to access and update data values without having to know how the data is structured and stored. In your application program, you simply access or update a field in the fielded buffer by referencing its identifier. To perform the operation, the FML run time determines the field location and data type.
FML is especially suited for use with Jolt clients because the client and server code can be in two languages (for example, Java and C); the client/server platforms can have different data type specifications; or the interface between the client and the server can change frequently.
The following tryOnFml examples illustrate the use
of the FML buffer type. The examples show a Jolt client using FML
buffers to pass data to a server. The server takes the buffer,
creates a new FML buffer to store the data, and passes that buffer
back to the Jolt client. The examples consist of the following
components.
- The listing “tryOnFml.java Code Example” is a Jolt client that contains a PASSFML service.
- The listing “tryOnFml.f16 Field Definitions” is an Oracle Tuxedo FML field definitions table used by the PASSFML service.
- The listing “tryOnFml.c Code Example” is a server code fragment that contains the server side C code for handling the data sent by the Jolt client.