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;* DESC
;* 	Download a file from Internet using the HTTP protocol.
;*
;* IN
;*  *tHTTP ; See the description on the T_PBL_HTTP_GET_FROM_WEB structure for the usage of the input / output fields.
;* 	 
;* OUT
;*  *tHTTP ; See the description on the T_PBL_HTTP_GET_FROM_WEB structure for the usage of the input / output fields.
;*
;* RET
;*  #WEB_OK                             ; If successful.
;*  #WEB_ERR_INVALID_PARAMETERS         ; If parameters are missing or invalid.
;*  #WEB_ERR_OUT_OF_MEMORY              ; If there is an error WHILE allocating memory for the data buffers.
;*  #WEB_ERR_FILE_CREATION              ; If there is an error while creating the file on the disk.
;*  #WEB_ERR_FILE_IO                    ; If there is an error while writing the file to the disk.
;*  #WEB_ERR_USER_ABORT                 ; If the callback return #False the download has been aborted by request.
;*  #WEB_ERR_HTTP_STATUS                ; If different from HTTP OK (200), the actual value will be returned in *tHTTP\iErrorCodeEx.
;*  #WEB_ERR_HTTP_OPEN                  ; Error in the API call to open.
;*  #WEB_ERR_HTTP_CONNECT               ; Error in the API call to connect.
;*  #WEB_ERR_HTTP_SET_PROXY             ; Error in the API call to set proxy.
;*  #WEB_ERR_HTTP_BASIC_AUTH            ; Error in the API call to basic auth.
;*  #WEB_ERR_HTTP_HTTP_OPEN             ; Error in the API call to HTTP open.
;*  #WEB_ERR_HTTP_HTTP_SEND             ; Error in the API call to HTTP send.
;*  #WEB_ERR_HTTP_HTTP_QUERY_STATUS     ; Error in the API call to query status.
;*  #WEB_ERR_HTTP_READ                  ; Error in the API call to read.
;*  #WEB_ERR_HTTP_CLOSE                 ; Error in the API call to close.
;*
;* EXAMPLE
;*  See the sample programs HTTPGetFromWeb_1.pb, HTTPGetFromWeb_2.pb.
;*
;*  The simplest form: download bar.zip in memory.
;*  The pointer to the allocated memory area will be returned in tHTTP\*DestBuffer.
;*  
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iDestination = #WEB_WRITE_TO_MEMORY
;*  HTTPGetFromWeb (@tHTTP)
;*  
;*  Same as above, loaded entirely in memory and then copied to the specified file.
;*  The memory in this case will be automatically freed by the procedure after
;*  saving the file to disk.
;*  
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iDestination = #WEB_WRITE_TO_FILE
;*  tHTTP\FullFileName$ = "c:\download\bar.zip"
;*  HTTPGetFromWeb (@tHTTP)
;*  
;*  Again we download bar.zip, but this time we don't load it entirely in memory.
;*  We try to load it in "chunks" of 16384 bytes, the proc will automatically save a chunk to
;*  file and then repeat the process until the download is completed.
;*  In this call we use a callback procedure as well.
;*  The callback procedure (see the prototype definition) will receive
;*  - a pointer to the tHTTP structure
;*  - the number of bytes downloaded up to this point
;*  - the total size of the download (if available, else 0)
;*  - the time passed in seconds from the start of the download.
;*  
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iDestination = #WEB_WRITE_TO_FILE
;*  tHTTP\FullFileName$ = "c:\download\bar.zip"
;*  tHTTP\iChunkSize = 16384
;*  tHTTP\fpCB_Working = @MyCallBack()
;*  HTTPGetFromWeb (@tHTTP)
;*  
;*  Same as above but using a proxy without authentication required.
;*  
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iAccess = #INTERNET_OPEN_TYPE_PROXY
;*  tHTTP\ProxyAndPort$ = "192.168.1.1:8080"
;*  tHTTP\iDestination = #WEB_WRITE_TO_FILE
;*  tHTTP\FullFileName$ = "c:\download\bar.zip"
;*  tHTTP\iChunkSize = 16384
;*  tHTTP\fpCB_Working = @MyCallBack()
;*  HTTPGetFromWeb (@tHTTP)
;*  
;*  Same as above but using a proxy requiring authentication,
;*  
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iAccess = #INTERNET_OPEN_TYPE_PROXY
;*  tHTTP\ProxyAndPort$ = "192.168.1.1:8080"
;*  tHTTP\ProxyUsername$ = "username"
;*  tHTTP\ProxyPassword$ = "password"
;*  tHTTP\iDestination = #WEB_WRITE_TO_FILE
;*  tHTTP\FullFileName$ = "c:\download\bar.zip"
;*  tHTTP\iChunkSize = 16384
;*  tHTTP\fpCB_Working = @MyCallBack()
;*  HTTPGetFromWeb (@tHTTP)
;*  
;*  Accessing an HTTP resource requiring basic authentication
;*  
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://username:password@www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iDestination = #WEB_WRITE_TO_FILE
;*  tHTTP\FullFileName$ = "c:\download\bar.zip"
;*  tHTTP\iChunkSize = 16384
;*  tHTTP\fpCB_Working = @MyCallBack();
;*  HTTPGetFromWeb (@tHTTP)
;*  
;*  Accessing an HTTP resource requiring basic authentication through a
;*  proxy requiring authentication
;*
;*  tHTTP\iThreadID = 0
;*  tHTTP\URL$ = "http://username:password@www.somedomain.com/foo/bar.zip"   
;*  tHTTP\iAccess = #INTERNET_OPEN_TYPE_PROXY
;*  tHTTP\ProxyAndPort$ = "192.168.1.1:8080"
;*  tHTTP\ProxyUsername$ = "username"
;*  tHTTP\ProxyPassword$ = "password"
;*  tHTTP\iDestination = #WEB_WRITE_TO_FILE
;*  tHTTP\FullFileName$ = "c:\download\bar.zip"
;*  tHTTP\iChunkSize = 16384
;*  tHTTP\fpCB_Working = @MyCallBack()
;*  HTTPGetFromWeb (@tHTTP) 
;*  
;* NOTES
;*  The procedure will fall back to use the chunk method even if "all in one block" is requested if the server doesn't return the 
;*  total size of the file we are about to download.
;*  This happen for example when downloading stock quotes from the Yahoo site.
;*
;*  The main callback procedure can optionally abort a download (if in chunk mode) when a user defined custom condition arise, 
;*  returning #False instead of #True.
;*
;*  Valid values for *tHTTP\iAccess 
;* 
;*   #INTERNET_OPEN_TYPE_DIRECT ; Try a direct connection to the Internet.
;*   #INTERNET_OPEN_TYPE_PROXY  ; Try to passes the requests to the proxy specified in ProxyAndPort$.
;*
;*  Valid values for *tHTTP\iFlags 
;*
;*   #INTERNET_FLAG_NO_UI               ; Disables the cookie dialog box if cookies received.
;*
;*   #INTERNET_FLAG_RELOAD              ; Forces a download of the requested file from the server, not from the cache.
;*
;*   #INTERNET_FLAG_NO_COOKIES          ; Does not automatically add cookie headers to requests, and does not automatically add 
;*                                      ; returned cookies to the cookie database.
;*
;*   #INTERNET_FLAG_NO_AUTO_REDIRECT    ; Does not automatically handle redirection in HttpSendRequest.

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; 2.01 (November 7, 2007)

; ! Solved the double authentication problem. Now a connection to a HTTP site requiring
;   authentication through a proxy server also requiring authentication is possible.

; + If the file to download is bigger than 10 MB the routine will automatically switch
;   to chunk mode using the default chunk size (65535) even if tHTTP\lChunkSize is not 
;   specified or it is equal to 0.

; + Added the param hRequest to the HTTPGetFromWeb_Start() callback, to access the opened
;   HTTP request handle to use custom HttpQueryInfo() calls (see example in sample1.pb).

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     tHTTP.T_PBL_HTTP_GET_FROM_WEB 
     tHTTP\sURL = "http://stromberg.bei.onlineglueck.de/1278627main.html"
     tHTTP\lThreadID = 0
     tHTTP\lDestination = #PBL_WRITE_TO_MEMORY  

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; 2.02 (Dicember 3, 2007)
; ! Changed the way to track the download progression internally, to correctly work 
;   with sites returning data in variable chunk sizes.
;   The problem was reported by Tranquil. Thank you !