OCI Queue async - Advanced Queuing

Detailed Description

OCILIB supports Oracle Advanced Queues features

Let's Oracle talk about this features !

Oracle Queues (from Oracle Streams - Advanced Queuing User's Guide)

Oracle Streams AQ provides database-integrated message queuing functionality. It is built on top of Oracle Streams and leverages the functions of Oracle Database so that messages can be stored persistently, propagated between queues on different computers and databases, and transmitted using Oracle Net Services and HTTP(S). Because Oracle Streams AQ is implemented in database tables, all operational benefits of high availability, scalability, and reliability are also applicable to queue data. Standard database features such as recovery, restart, and security are supported by Oracle Streams AQ. You can use database development and management tools such as Oracle Enterprise Manager to monitor queues. Like other database tables, queue tables can be imported and exported.

OCILIB implementation

OCILIB provides a (nearly) full C implementation of Advanced Queues available in Oracle OCI and proposes the following datatypes :

• OCI_Msg : Implementation of message to enqueue/dequeue from/to queues
• OCI_Enqueue : Implementation of enqueuing process
• OCI_Dequeue : Implementation of dequeuing process
• OCI_Agent : Implementation of Advanced queues Agents

Note that the only AQ features not supported yet by OCILIB are :

• Payloads of type AnyData
• Enqueuing/dequeuing arrays of messages
• Optionnal delivery mode introduced in 10gR2

OCILIB provides as well a C API to administrate queues and queue tables initially reserved to PL/SQL and Java (wrappers around PL/SQL calls). This API, based on internal PL/SQL calls wrapping the DBMS_AQADM packages procedures, allow the following actions :

• create, alter, drop and purge queue tables (OCI_QueueTableXXX calls)
• create, alter, drop, start, stop queues (OCI_QueueXXX calls)

Note that the user connected to the database needs particular privileges to manipulate or administrate queues (See Oracle Streams - Advanced Queuing User's Guide for more informations on these privileges)

Example

#include "ocilib.h"

int main(int argc, char *argv[])
{
    OCI_Connection *con;
    OCI_Enqueue    *enq;
    OCI_Dequeue    *deq;
    OCI_Msg        *msg;
    OCI_TypeInfo   *inf;
    OCI_Object     *obj;
   
    OCI_Initialize(NULL, NULL, OCI_ENV_DEFAULT);
     
    con = OCI_ConnectionCreate("db", "usr", "pwd", OCI_SESSION_DEFAULT);

    inf = OCI_TypeInfoGet(con, "MY_MESSAGE", OCI_TIF_TYPE);
    
    enq = OCI_EnqueueCreate(inf, "my_queue");
    deq = OCI_DequeueCreate(inf, "my_queue");
    
    msg = OCI_MsgCreate(inf);
    obj = OCI_ObjectCreate(con, inf);

    OCI_ObjectSetString(obj, "TITLE", "NEXT MEETING");
    OCI_ObjectSetString(obj, "CONTENT", "12:00 PM IN STARBUCKS");

    OCI_MsgSetObject(msg, obj);

    OCI_EnqueuePut(enq, msg);

    OCI_MsgFree(msg);
    OCI_ObjectFree(obj);

    OCI_Commit(con);
    
    msg = OCI_DequeueGet(deq);
    obj = OCI_MsgGetObject(msg);

    printf("MSG '%s' => %s\n",  OCI_ObjectGetString(obj, "TITLE"),
                                OCI_ObjectGetString(obj, "CONTENT"));

    OCI_EnqueueFree(enq);
    OCI_DequeueFree(deq);
    OCI_ConnectionFree(con);

    OCI_Cleanup();

   return EXIT_SUCCESS;
}