C++

Async Methods Returning an Object

See more Async Examples

Demonstrates how to call an asynchronous method that returns an object. This example reads email from a POP3 server using the Async versions of the Chilkat methods. C++

#include <CkMailMan.h>
#include <CkTask.h>
#include <CkEmail.h>

void ChilkatSample(void)
    {
    bool success = false;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    success = false;

    CkMailMan mailman;

    // Set the POP3 server's hostname
    mailman.put_MailHost("pop.example.com");

    // Set the POP3 login/password and any other requirements..
    mailman.put_PopUsername("myLogin");
    mailman.put_PopPassword("myPassword");
    mailman.put_PopSsl(true);
    mailman.put_MailPort(995);

    // Connect to the POP3 server:
    CkTask *task = mailman.Pop3BeginSessionAsync();
    if (mailman.get_LastMethodSuccess() == false) {
        std::cout << mailman.lastErrorText() << "\r\n";
        return;
    }

    // Start the background task.
    success = task->Run();
    if (!success) {
        std::cout << task->lastErrorText() << "\r\n";
        delete task;
        return;
    }

    // Wait for the POP3 connect task to finish.
    // The true/false returned by Wait applies to the Wait method call, not the task.
    int maxWaitMs = 30000;
    success = task->Wait(maxWaitMs);
    if (!success || (task->get_StatusInt() != 7) || (task->get_TaskSuccess() != true)) {
        if (!success) {
            // The task.LastErrorText applies to the Wait method call.
            std::cout << task->lastErrorText() << "\r\n";
        }
        else {
            // The ResultErrorText applies to the underlying task method call (i.e. the Pop3BeginSession)
            std::cout << task->status() << "\r\n";
            std::cout << task->resultErrorText() << "\r\n";
        }

        delete task;
        return;
    }

    delete task;

    // Get the number of messages in the mailbox.
    task = mailman.GetMailboxCountAsync();

    // To keep the example short, we'll skip handling failures.
    // The failures would be handled in the same way as shown above.

    success = task->Run();
    success = task->Wait(maxWaitMs);
    int numMessages = task->GetResultInt();
    delete task;
    if (numMessages == 0) {
        return;
    }

    CkEmail email;

    int i;
    for (i = 1; i <= numMessages; i++) {

        task = mailman.FetchByMsgnumAsync(i);
        if (mailman.get_LastMethodSuccess() == false) {
            std::cout << mailman.lastErrorText() << "\r\n";
            return;
        }

        success = task->Run();
        success = task->Wait(maxWaitMs);
        if (!success || (task->get_StatusInt() != 7) || (task->get_TaskSuccess() != true)) {
            if (!success) {
                // The task.LastErrorText applies to the Wait method call.
                std::cout << task->lastErrorText() << "\r\n";
            }
            else {
                // The ResultErrorText applies to the underlying task method call (i.e. the FetchByMsgnum)
                std::cout << task->status() << "\r\n";
                std::cout << task->resultErrorText() << "\r\n";
            }

            delete task;
            return;
        }

        // Each Chilkat object that can be a return value of an asynchronous task will
        // have a method named LoadTaskResult.  The object returned in the underlying
        // asynchronous method call is retrieved by calling LoadTaskResult. 

        // To say it another way: The application will provide a pre-existing object of
        // the desired return type (in this case it is an email object).  This object is
        // loaded by calling LoadTaskResult.  

        success = email.LoadTaskResult(*task);
        delete task;

        if (!success) {
            std::cout << email.lastErrorText() << "\r\n";
            return;
        }
        else {
            std::cout << email.ck_from() << ": " << email.subject() << "\n" << "\r\n";
        }

    }
    }