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How to change the internet connection timeout
by , 17-Aug-2010 at 01:00 AM (15936 Views)
When your Visual DataFlex application makes an external call to a webservice the main program waits for its completion. If the request does not return immediately several things can be the cause. Your connection to your ISP can slow, the webserver you try to reach is busy, can be difficult found etc. If you want your application to continue as soon as possible and know (and this is the unknown keyfactor) that particular call should not take more than a couple of milliseconds to complete you can query and change the internet timeout value. There are two Windows API calls (InternetQueryOption and InternetSetOption). General information can be read here.
When changing any option you have to be aware of the range and possible side effects that may occur. For example; in the sample code of this blog I query and set the global default options which means it changes the behavior for Internet Explorer and all Internet actions afterwards. I do that because we change an option before calling a webservice and thus we do not operate on the specific handle.
There are many internet options you can query and can set. I would advise to always query first, then set, and later reset the option to the queried value.
The Visual DataFlex side of the option query and set instructions is:
Back to the timeout issue. As you can read here there are many options that do something with timeout. Which one to choose? Should we use a connection timeout setting or a receive (and send) timeout setting? In case of a webservice I would choose for a receive timeout but I leave that to you.Code:External_Function WinAPI_InternetQueryOption "InternetQueryOptionA" WinInet.Dll Handle hInternet DWORD dwOption Pointer lpBuffer Pointer lpdwBufferLength Returns Boolean External_Function WinAPI_InternetSetOption "InternetSetOptionA" WinInet.Dll Handle hInternet Dword dwOption Pointer lpBuffer Dword dwBufferLength Returns Boolean
So let us first retrieve the current receive timeout.
The IntenetQueryOption can also return the size of the buffer needed but in this case an integer is fine.Code:Move (SizeOfType (Integer)) To dwBufferLength Move 0 To iCurrentReceiveTimeOut Move (WinAPI_InternetQueryOption (0, INTERNET_OPTION_RECEIVE_TIMEOUT, AddressOf (iCurrentReceiveTimeOut), AddressOf (dwBufferLength))) To bQueryOptionSucceeded
In my computer the returned timeout is 30000 milliseconds (= 30 seconds).
We change the timeout to 2000 milliseconds by:
Then we call the webserviceCode:Move (WinAPI_InternetSetOption (0, INTERNET_OPTION_RECEIVE_TIMEOUT, AddressOf (iNewReceiveTimeOut), dwBufferLength)) To bQueryOptionSucceeded
As said before I think it is a good habit to reset the just changed value back to the queried valueCode:Get wsSayHello Of oWSTestService "Vincent" To sText Get peTransferStatus Of oWSTestService To eTransferStatus
In full the code is:Code:Move (WinAPI_InternetSetOption (0, INTERNET_OPTION_RECEIVE_TIMEOUT, AddressOf (iCurrentReceiveTimeOut), dwBufferLength)) To bQueryOptionSucceeded
Code:Define INTERNET_OPTION_CALLBACK For 1 Define INTERNET_OPTION_CONNECT_TIMEOUT For 2 Define INTERNET_OPTION_CONNECT_RETRIES For 3 Define INTERNET_OPTION_CONNECT_BACKOFF For 4 Define INTERNET_OPTION_SEND_TIMEOUT For 5 Define INTERNET_OPTION_CONTROL_SEND_TIMEOUT For INTERNET_OPTION_SEND_TIMEOUT Define INTERNET_OPTION_RECEIVE_TIMEOUT For 6 Define INTERNET_OPTION_CONTROL_RECEIVE_TIMEOUT For INTERNET_OPTION_RECEIVE_TIMEOUT Define INTERNET_OPTION_DATA_SEND_TIMEOUT For 7 Define INTERNET_OPTION_DATA_RECEIVE_TIMEOUT For 8 Define INTERNET_OPTION_HANDLE_TYPE For 9 Define INTERNET_OPTION_LISTEN_TIMEOUT For 11 Define INTERNET_OPTION_READ_BUFFER_SIZE For 12 Define INTERNET_OPTION_WRITE_BUFFER_SIZE For 13 Define INTERNET_OPTION_ASYNC_ID For 15 Define INTERNET_OPTION_ASYNC_PRIORITY For 16 Define INTERNET_OPTION_PARENT_HANDLE For 21 Define INTERNET_OPTION_KEEP_CONNECTION For 22 Define INTERNET_OPTION_REQUEST_FLAGS For 23 Define INTERNET_OPTION_EXTENDED_ERROR For 24 Define INTERNET_OPTION_OFFLINE_MODE For 26 Define INTERNET_OPTION_CACHE_STREAM_HANDLE For 27 Define INTERNET_OPTION_USERNAME For 28 Define INTERNET_OPTION_PASSWORD For 29 Define INTERNET_OPTION_ASYNC For 30 Define INTERNET_OPTION_SECURITY_FLAGS For 31 Define INTERNET_OPTION_SECURITY_CERTIFICATE_STRUCT For 32 Define INTERNET_OPTION_DATAFILE_NAME For 33 Define INTERNET_OPTION_URL For 34 Define INTERNET_OPTION_SECURITY_CERTIFICATE For 35 Define INTERNET_OPTION_SECURITY_KEY_BITNESS For 36 Define INTERNET_OPTION_REFRESH For 37 Define INTERNET_OPTION_PROXY For 38 Define INTERNET_OPTION_SETTINGS_CHANGED For 39 Define INTERNET_OPTION_VERSION For 40 Define INTERNET_OPTION_USER_AGENT For 41 Define INTERNET_OPTION_END_BROWSER_SESSION For 42 Define INTERNET_OPTION_PROXY_USERNAME For 43 Define INTERNET_OPTION_PROXY_PASSWORD For 44 Define INTERNET_OPTION_CONTEXT_VALUE For 45 Define INTERNET_OPTION_CONNECT_LIMIT For 46 Define INTERNET_OPTION_SECURITY_SELECT_CLIENT_CERT For 47 Define INTERNET_OPTION_POLICY For 48 Define INTERNET_OPTION_DISCONNECTED_TIMEOUT For 49 Define INTERNET_OPTION_CONNECTED_STATE For 50 Define INTERNET_OPTION_IDLE_STATE For 51 Define INTERNET_OPTION_OFFLINE_SEMANTICS For 52 Define INTERNET_OPTION_SECONDARY_CACHE_KEY For 53 Define INTERNET_OPTION_CALLBACK_FILTER For 54 Define INTERNET_OPTION_CONNECT_TIME For 55 Define INTERNET_OPTION_SEND_THROUGHPUT For 56 Define INTERNET_OPTION_RECEIVE_THROUGHPUT For 57 Define INTERNET_OPTION_REQUEST_PRIORITY For 58 Define INTERNET_OPTION_HTTP_VERSION For 59 Define INTERNET_OPTION_RESET_URLCACHE_SESSION For 60 Define INTERNET_OPTION_ERROR_MASK For 62 Define INTERNET_OPTION_FROM_CACHE_TIMEOUT For 63 Define INTERNET_OPTION_BYPASS_EDITED_ENTRY For 64 Define INTERNET_OPTION_DIAGNOSTIC_SOCKET_INFO For 67 Define INTERNET_OPTION_CODEPAGE For 68 Define INTERNET_OPTION_CACHE_TIMESTAMPS For 69 Define INTERNET_OPTION_DISABLE_AUTODIAL For 70 Define INTERNET_OPTION_MAX_CONNS_PER_SERVER For 73 Define INTERNET_OPTION_MAX_CONNS_PER_1_0_SERVER For 74 Define INTERNET_OPTION_PER_CONNECTION_OPTION For 75 Define INTERNET_OPTION_DIGEST_AUTH_UNLOAD For 76 Define INTERNET_OPTION_IGNORE_OFFLINE For 77 Define INTERNET_OPTION_IDENTITY For 78 Define INTERNET_OPTION_REMOVE_IDENTITY For 79 Define INTERNET_OPTION_ALTER_IDENTITY For 80 Define INTERNET_OPTION_SUPPRESS_BEHAVIOR For 81 Define INTERNET_OPTION_AUTODIAL_MODE For 82 Define INTERNET_OPTION_AUTODIAL_CONNECTION For 83 Define INTERNET_OPTION_CLIENT_CERT_CONTEXT For 84 Define INTERNET_OPTION_AUTH_FLAGS For 85 Define INTERNET_OPTION_COOKIES_3RD_PARTY For 86 Define INTERNET_OPTION_DISABLE_PASSPORT_AUTH For 87 Define INTERNET_OPTION_SEND_UTF8_SERVERNAME_TO_PROXY For 88 Define INTERNET_OPTION_EXEMPT_CONNECTION_LIMIT For 89 Define INTERNET_OPTION_ENABLE_PASSPORT_AUTH For 90 Define INTERNET_OPTION_HIBERNATE_INACTIVE_WORKER_THREADS For 91 Define INTERNET_OPTION_ACTIVATE_WORKER_THREADS For 92 Define INTERNET_OPTION_RESTORE_WORKER_THREAD_DEFAULTS For 93 Define INTERNET_OPTION_SOCKET_SEND_BUFFER_LENGTH For 94 Define INTERNET_OPTION_PROXY_SETTINGS_CHANGED For 95 // Internet Handle types Define INTERNET_HANDLE_TYPE_INTERNET for 1 Define INTERNET_HANDLE_TYPE_CONNECT_FTP for 2 Define INTERNET_HANDLE_TYPE_CONNECT_GOPHER for 3 Define INTERNET_HANDLE_TYPE_CONNECT_HTTP for 4 Define INTERNET_HANDLE_TYPE_FTP_FIND for 5 Define INTERNET_HANDLE_TYPE_FTP_FIND_HTML for 6 Define INTERNET_HANDLE_TYPE_FTP_FILE for 7 Define INTERNET_HANDLE_TYPE_FTP_FILE_HTML for 8 Define INTERNET_HANDLE_TYPE_GOPHER_FIND for 9 Define INTERNET_HANDLE_TYPE_GOPHER_FIND_HTML for 10 Define INTERNET_HANDLE_TYPE_GOPHER_FILE for 11 Define INTERNET_HANDLE_TYPE_GOPHER_FILE_HTML for 12 Define INTERNET_HANDLE_TYPE_HTTP_REQUEST for 13 Define INTERNET_HANDLE_TYPE_FILE_REQUEST for 14 External_Function WinAPI_InternetQueryOption "InternetQueryOptionA" WinInet.Dll Handle hInternet DWORD dwOption Pointer lpBuffer Pointer lpdwBufferLength Returns Boolean External_Function WinAPI_InternetSetOption "InternetSetOptionA" WinInet.Dll Handle hInternet Dword dwOption Pointer lpBuffer Dword dwBufferLength Returns Boolean Use dfClient.pkg Use cWSTestService.pkg Use Windows.pkg DEFERRED_VIEW Activate_oNewView FOR ; ; Object oNewView is a dbView Set Border_Style to Border_Thick Set Location to 2 2 Set Size to 200 300 Object oWSTestService is a cWSTestService End_Object Object oButton1 is a Button Set Label to "oButton1" Set Location to 57 63 Procedure OnClick String sText dWord dwBufferLength Boolean bQueryOptionSucceeded Integer iCurrentReceiveTimeOut iNewReceiveTimeOut eTransferStatus Move (SizeOfType (Integer)) to dwBufferLength Move 0 To iCurrentReceiveTimeOut Move (WinAPI_InternetQueryOption (0, INTERNET_OPTION_RECEIVE_TIMEOUT, AddressOf (iCurrentReceiveTimeOut), AddressOf (dwBufferLength))) To bQueryOptionSucceeded Move 2000 To iNewReceiveTimeOut Move (WinAPI_InternetSetOption (0, INTERNET_OPTION_RECEIVE_TIMEOUT, AddressOf (iNewReceiveTimeOut), dwBufferLength)) To bQueryOptionSucceeded Get wsSayHello Of oWSTestService "Vincent" To sText Get peTransferStatus Of oWSTestService To eTransferStatus Move (WinAPI_InternetSetOption (0, INTERNET_OPTION_RECEIVE_TIMEOUT, AddressOf (iCurrentReceiveTimeOut), dwBufferLength)) To bQueryOptionSucceeded If (eTransferStatus = wssOK) Begin Send Info_Box sText "TestService Results" End Else Begin Send Stop_Box eTransferStatus "Transfer Status" End End_Procedure End_Object CD_End_Object
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