Introduction to EPOC OPL Development

Getting Started

OPL applications can be developed either using the OPL environment on an EPOC device or the Symbian OPL SDK that runs on a PC. Currently the Psion 5mx and 7, Oregon Scientific Osaris and Ericsson MC218 all include the OPL development environment. Generally however most development will be undertaken (or at least completed) using the SDK which can be obtained by either:

• registering on the Symbian Developer Network and download the SDK. (You can also order the SDKs on CD-ROM from Symbian for a small handling charge.) or
• purchasing the Wrox press book Professional Symbian Programming book which comes with a CD containing all four SDKs (the fourth being the EPOC Connect SDK for PC connectivity development).

The Wrox book contains a chapter on OPL, but mainly concentrates on C++ and is therefore probably not worthwhile unless you also have an interest in C++ development. Even if you buy the book registration at Symbian's developer network is worthwhile as the site contains a number of other useful resources, including OPL extensions (OPMs and OPXs), OPL knowledgebase and a resource file tutorial amongst others.

The SDK contains an emulator for 1/2 VGA (640x240), full VGA (640x480) and large (800x600) EPOC screens and includes all the standard EPOC functionality and applications along with full documentation and some example programs. It also contains a number of useful utilities for creating resource, graphic, help and installation files that can not be undertaken on an EPOC machine unless you use third party tools.

To run the SDK you will require a Pentium PC running Windows 95 or above. (Incidentally the SDK also provides an excellent free route to evaluate the core EPOC applications if you were thinking of buying an EPOC machine.)

The Development Process

The process of developing an OPL program or application can consist of simply writing, translating and running the code directly on your EPOC machine. However the production of a fully featured application is a little more involved.

(The distinction between a program and an application is really whether an Icon appears on the Extras bar, similar to the Windows Start menu, from which the application can be run. A program can only be run by finding and executing the compiled code.)

The process of developing an application has five elements:

• writing and testing the OPL code
• preparing a resource file (primarily for multiple lingual versions)
• developing and packaging bit map icons or other graphical program elements
• writing the help documentation
• packaging the final application in an installation file.