Prerequisites for Internet Client Classes
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Some actions taken by an Internet client (reading a file, for example) have prerequisite actions (in this case, establishing an Internet connection). The following tables list the prerequisites for some client actions.
General Internet URL (FTP, Gopher, or HTTP)
| Action | Prerequisite |
|---|---|
| Establish a connection. | Create a CInternetSession to establish the basis of an Internet client application. |
| Open a URL. | Establish a connection. Call CInternetSession::OpenURL. The OpenURL function returns a read-only resource object. |
| Read URL data. | Open the URL. Call CInternetFile::Read. |
| Set an Internet option. | Establish a connection. Call CInternetSession::SetOption. |
| Set a function to be called with status information. | Establish a connection. Call CInternetSession::EnableStatusCallback. Override CInternetSession::OnStatusCallback to handle calls. |
FTP
| Action | Prerequisite |
|---|---|
| Establish an FTP connection. | Create a CInternetSession as the basis of this Internet client application. Call CInternetSession::GetFtpConnection to create a CFtpConnection object. |
| Find the first resource. | Establish an FTP connection. Create a CFtpFileFind object. Call CFtpFileFind::FindFile. |
| Enumerate all available resources. | Find the first file. Call CFtpFileFind::FindNextFile until it returns FALSE. |
| Open an FTP file. | Establish an FTP connection. Call CFtpConnection::OpenFile to create and open a CInternetFile object. |
| Read an FTP file. | Open an FTP file with read access. Call CInternetFile::Read. |
| Write to an FTP file. | Open an FTP file with write access. Call CInternetFile::Write. |
| Change the client's directory on the server. | Establish an FTP connection. Call CFtpConnection::SetCurrentDirectory. |
| Retrieve the client's current directory on the server. | Establish an FTP connection. Call CFtpConnection::GetCurrentDirectory. |
HTTP
| Action | Prerequisite |
|---|---|
| Establish an HTTP connection. | Create a CInternetSession as the basis of this Internet client application. Call CInternetSession::GetHttpConnection to create a CHttpConnection object. |
| Open an HTTP file. | Establish an HTTP connection. Call CHttpConnection::OpenRequest to create a CHttpFile object. Call CHttpFile::AddRequestHeaders. Call CHttpFile::SendRequest. |
| Read an HTTP file. | Open an HTTP file. Call CInternetFile::Read. |
| Get information about an HTTP request. | Establish an HTTP connection. Call CHttpConnection::OpenRequest to create a CHttpFile object. Call CHttpFile::QueryInfo. |
Gopher
| Action | Prerequisite |
|---|---|
| Establish a gopher connection. | Create a CInternetSession as the basis of this Internet client application. Call CInternetSession::GetGopherConnection to create a CGopherConnection. |
| Find the first file in the current directory. | Establish a gopher connection. Create a CGopherFileFind object. Call CGopherConnection::CreateLocator to create a CGopherLocator object. Pass the locator to CGopherFileFind::FindFile. Call CGopherFileFind::GetLocator to get the locator of a file if you need it later. |
| Enumerate all available files. | Find the first file. Call CGopherFileFind::FindNextFile until it returns FALSE. |
| Open a gopher file. | Establish a gopher connection. Create a gopher locator with CGopherConnection::CreateLocator or find a locator with CGopherFileFind::GetLocator. Call CGopherConnection::OpenFile. |
| Read a gopher file. | Open a gopher file. Use CGopherFile. |
See Also
Win32 Internet Extensions (WinInet)
MFC Classes for Creating Internet Client Applications
Writing an Internet Client Application Using MFC WinInet Classes