The Message Queue Library example demonstrates how to use Open C APIs for developing applications that use Open C standard libraries on Symbian platform. This example uses the APIs of the message queue library to create/close message queues and send/receive messages and also get information on created message queues.
Click on the following link to download the example: opencmessagequeuelibraryex.zip
Click: browse to view the example code.
The following sections provide information about the implementation of the example.
Description
OpenCMessageQueueClientEx is a C Application that uses the Message Queue library. This application uses main() as the entry point for the application. This is a simple console based application. The application uses Message Queue library (OpenCMessageQueueLibrary.dll) APIs. The Main thread of the application creates two message queues, and two threads. Thread one will send message to message queue 1 and waits for messages from message queue 2. Then thread one will send message to message queue 2 and waits for messages from message queue 1. If a user tries to create a message queue using OpenCMessageQueueLibrary.dll with the already existing name, it will just return the existing message queue Id. The application has its own icon and can be launched from the UI both in the emulator and in the device.
Capabilities
The program capabilities are defined in:MessageQueueLibrary.mmp (DLL - library): CAPABILITY ALL -TCB MessageQueueClient.mmp(EXE - application): CAPABILITY
NONE. Module hierarchy
This application has 2 modules as below:Message Queue Library (DLL) that exports set of apis for the user.
OpenCMessageQueueLibraryEx\engine : The application (EXE) that demonstrates the usage of Open C APIs and also those APIs exported by Message Queue Library.
(OpenCMessageQueueLibraryEx\exe) : This example will create a DLL which exports set of generic APIs with which the user can do message queue related operations. To give a rough idea on how to use these apis, an EXE is provided that creates threads and does send/receive on message queues using those exported apis.
APIs used
msgget
msgctl
msgrcv
msgsnd
semget
semctl
semop
OpenCMessageQueueLibraryEx\group directory
and build the application. The Message Queue Library application
consists of two modules, which should be built in the following order:
engine - which builds the generic message queue library exe - which
builds an EXE that demonstrates the usage of this library The definition
for the whole application can be found in thebld.infin the group subdirectory of the applications main directory.