okutil_http_download

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 header to Included
9 Reference

Description

Download from given URL to a file, with https(SSL) support

Syntax

int okutil_http_download( LPCSTR lpcszURL, LPCSTR lpcszFileName, int nConnectTimeout = 0, int nResponseTimeout = 0, BOOL bIgnoreCertError = FALSE, BOOL bWait = TRUE, BOOL bShowMsg = FALSE )

Parameters

lpcszURL: [input]The URL specify the target file to download
lpcszFileName: [input]The local file to receive data downloaded from lpcszURL
nConnectionTimeout: [input]The number of seconds to specify timeout limit when connect to server
nResponseTimeout: [input]The number of seconds to specify timeout limit waiting for response of a request
bIgnoreCertError: [input]Ignore Error
bWait: [input]Set as FALSE to download in a separate thread.
bShowMsg: [input]True to dump message to Messages Log after download

Return

If bWait = true, return OHTTP_E_OK for success, other negative values are error code. If bWait = false, return 0 for download starts，other value for previous download not completed. System variable @OCDL can check the download status, see EX2.

Examples

EX1

this example will download a CSV file and import to worksheet

//assume active book empty
void stock()
{
	string strSymbol = "MSFT";//you need apikey if searching any other stock
	string strFile = GetOriginPath(ORIGIN_PATH_USER) + strSymbol + "_stock.csv";
	string strURL = "https://www.alphavantage.co/query?function=TIME_SERIES_DAILY&symbol=";
	strURL += strSymbol;
	strURL += "&apikey=demo&datatype=csv";
	string result;
	int err = okutil_http_download(strURL, strFile);
	if( err != 0 ) {
		out_int("err = ", err);
		return;
	}
	Worksheet wks = Project.ActiveLayer();
	ASCIMP  ai;
	if(AscImpReadFileStruct(strFile, &ai)==0) {
		ai.iSubheaderLines = 1;
		ai.nLongNames = 1;
		wks.ImportASCII(strFile, ai);
		Column col(wks, 0);
		col.SetFormat(OKCOLTYPE_DATE, "yyyy'-'MM'-'dd");
	}
}

EX2

this example shows Origin downloads file in another thread, meanwhile you can use Origin to do other things.

//open Messages Log to see the download begin/end message
void okutil_http_download_ex2()
{
	string strName = "ECMWF_ERA-40_subset.nc";
	string strFile = GetOriginPath(ORIGIN_PATH_USER) + strName;
	string strURL = "https://www.unidata.ucar.edu/software/netcdf/examples/" + strName;
	
	string strMsg;
	double err;
	BOOL bWait = FALSE;	// download file in a separate thread
	BOOL bShowMsg = TRUE; // message log will show message after download complete
	
	if( okutil_http_download(strURL, strFile, 0, 0, FALSE, bWait, bShowMsg) )
	{
		LT_get_var("@OCDL", &err); 
		strMsg.Format("previous download not completed %.2f%%\n", err);
	}
	else
	{
		LT_execute("sec -p 1"); //wait @OCDL update
		
		LT_get_var("@OCDL", &err); 
		if( err < 0 ) 
		{
			strMsg.Format("err = %g\n", err);
		}
		else if( err == 0 ) 
		{
			strMsg.Format("download complete: %s\n", strName);
		}
		else
		{
			strMsg.Format("downloading %.2f%%\n", err);
		}
	}
	strMsg.Write(WRITE_MESSAGE_LOG);
}