Click here to Skip to main content
14,544,540 members

Using WinInet to Call a Server Script Asynchronously

Rate this:
4.77 (6 votes)
Please Sign up or sign in to vote.
4.77 (6 votes)
24 Aug 2007CPOL
Using WinInet to call a server script asynchronously

Introduction

I wanted to find a simple way of running a script (e.g. Perl, PHP, etc.) on a webserver but it needed to be asynchronous as I didn't want the application to hang while waiting for the webserver's response. I didn't need to read any output from the script so all the solutions I could find were overly complicated for my needs.

Theory

  1. Use INTERNET_FLAG_ASYNC to open the session
  2. Set a status callback using InternetSetStatusCallback
  3. Open the connection using InternetOpenUrl
  4. Read the handle when the callback function receives INTERNET_STATUS_HANDLE_CREATED
  5. Free up everything when the call has finished and the callback function receives INTERNET_STATUS_REQUEST_COMPLETE

Using the Code

The complete code is:

HINTERNET    hInternetSession = NULL;   
HINTERNET    hURL = NULL;

typedef struct
{
    HWND        hWindow;     // window handle
    HINTERNET   hResource;   // HINTERNET handle created by InternetOpenUrl
} REQUEST_CONTEXT;

REQUEST_CONTEXT    request_context;

void __stdcall InternetCallbackFunction(HINTERNET hInternet,
                        DWORD dwContext,
                        DWORD dwInternetStatus,
                        LPVOID lpvStatusInformation,
                        DWORD dwStatusInformationLength)
{
    REQUEST_CONTEXT* cpContext;
    INTERNET_ASYNC_RESULT* res;

    cpContext = (REQUEST_CONTEXT*)dwContext;

    // what has this callback function been told has happened?
    switch (dwInternetStatus)
    {
        case INTERNET_STATUS_HANDLE_CREATED:
            // get the handle now that it has been created so it can be freed up later
            res = (INTERNET_ASYNC_RESULT*)lpvStatusInformation;
            hURL = (HINTERNET)(res->dwResult);

            break;

        case INTERNET_STATUS_REQUEST_COMPLETE:
            // script has been called so close handles now and 
	   // cancel the callback function
            InternetCloseHandle(hURL);
            InternetSetStatusCallback(hInternetSession, NULL);
            InternetCloseHandle(hInternetSession);

            // flag as having been completed now
            hURL = NULL;
            hInternetSession = NULL;

            break;
    }
}

void RunScript(char* szURL)
{
    // only run this script if finished all others
    if (hInternetSession == NULL)
    {
        hInternetSession = InternetOpen("Microsoft Internet Explorer",
                        INTERNET_OPEN_TYPE_PRECONFIG,
                        NULL,
                        NULL,
                        INTERNET_FLAG_ASYNC);
        
        if (hInternetSession != NULL)
        {
            // set the callback function
            InternetSetStatusCallback(hInternetSession,
                        (INTERNET_STATUS_CALLBACK)InternetCallbackFunction);

            // run the script
            hURL = InternetOpenUrl(hInternetSession,
                        szURL,
                        NULL,
                        0,
                        INTERNET_FLAG_RELOAD |
                        INTERNET_FLAG_PRAGMA_NOCACHE |
                        INTERNET_FLAG_NO_CACHE_WRITE,
                        (unsigned long)(&request_context));
        }
    }
}   

History

  • 24th August, 2007: Initial post

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Share

About the Author

Sean OConnor
Web Developer
United Kingdom United Kingdom
No Biography provided

Comments and Discussions

 
GeneralMy vote of 3 Pin
badwei22-Aug-10 19:16
Memberbadwei22-Aug-10 19:16 
General997 error Pin
Cyrus the Virus6-May-08 2:05
MemberCyrus the Virus6-May-08 2:05 
GeneralRe: 997 error Pin
ShilpiP18-May-08 21:15
MemberShilpiP18-May-08 21:15 
GeneralRe: 997 error Pin
Cyrus the Virus18-May-08 23:49
MemberCyrus the Virus18-May-08 23:49 
GeneralRe: 997 error Pin
ShilpiP18-May-08 23:59
MemberShilpiP18-May-08 23:59 
GeneralRe: 997 error Pin
Cyrus the Virus19-May-08 0:18
MemberCyrus the Virus19-May-08 0:18 
GeneralRe: 997 error Pin
ShilpiP19-May-08 0:42
MemberShilpiP19-May-08 0:42 
GeneralRe: 997 error Pin
Cyrus the Virus19-May-08 0:55
MemberCyrus the Virus19-May-08 0:55 
GeneralRe: 997 error Pin
ShilpiP19-May-08 1:36
MemberShilpiP19-May-08 1:36 
GeneralRe: 997 error Pin
Anandtv28-May-08 2:31
MemberAnandtv28-May-08 2:31 
GeneralRe: 997 error Pin
ShilpiP28-May-08 2:57
MemberShilpiP28-May-08 2:57 
AnswerRe: 997 error Pin
Anandtv28-May-08 20:04
MemberAnandtv28-May-08 20:04 
GeneralRe: 997 error Pin
ShilpiP28-May-08 20:44
MemberShilpiP28-May-08 20:44 
GeneralExactly what I was looking for! Pin
Gilad Novik27-Aug-07 7:24
MemberGilad Novik27-Aug-07 7:24 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

Article
Posted 24 Aug 2007

Stats

42.5K views
20 bookmarked