Understanding and Using APEX Application Processes

What Are Application Processes

Application processes are PL/SQL blocks that run at specific points during every page request. Unlike page processes tied to a single page, application processes execute globally. They are configured in Shared Components and are essential for session-wide state, global business rules, and code that runs on every request.

Process Points

On New Session: Runs once when a session is created. Ideal for loading user preferences:

BEGIN
    SELECT default_language, theme_preference, items_per_page
      INTO :G_LANGUAGE, :G_THEME, :G_PAGE_SIZE
      FROM user_preferences WHERE username = :APP_USER;
EXCEPTION
    WHEN NO_DATA_FOUND THEN
        :G_LANGUAGE := 'EN'; :G_THEME := 'LIGHT'; :G_PAGE_SIZE := 25;
END;

Before Header: Runs before every page render. Use for notification counts or alert checks.

On Demand (AJAX Callback): Creates a named PL/SQL entry point callable from JavaScript:

-- Application Process: GET_EMPLOYEE_COUNT
DECLARE l_count NUMBER;
BEGIN
    SELECT COUNT(*) INTO l_count FROM employees
     WHERE department_id = APEX_APPLICATION.G_X01;
    HTP.P(l_count);
END;

// JavaScript:
apex.server.process("GET_EMPLOYEE_COUNT", {x01: deptId}, {
    success: function(data) { apex.item("P10_COUNT").setValue(data); }
});

Conditions and Sequence

Each process can have a Server-Side Condition controlling execution. The Sequence number controls order. Keep sequences well-spaced (10, 20, 30) to allow inserting new processes later.

Performance Considerations

Before Header processes run on every page view. Keep them lightweight. If a process involves expensive queries, cache the result in an application item refreshed only when data changes rather than recalculating on every load.