DataFlex

Receiving a String

See more Socket/SSL/TLS Examples

Demonstrates how to receive character data on a socket connection. The code for this example immediately follows the session logs (below). You should first read throught the code w/ comments and then refer back to these session logs...

SessionLog for 1st ReceiveString method call

SPACE chars are shown as \x20. It is easy to see that the accented characters (á, é, í, ó, ú, ý) are each represented by a single byte in the received data: \xE1, \xE9, 0xED, \xF3, \xFA, and \xFD.

ReceiveString1: HTTP/1.1\x20200\x20OK\r\n
	Content-Length:\x20140\r\n
	Content-Type:\x20text/html\r\n
	Last-Modified:\x20Thu,\x2001\x20Oct\x202009\x2012:29:48\x20GMT\r\n
	Accept-Ranges:\x20bytes\r\n
	ETag:\x20\"2e66a6dd9242ca1:28b\"\r\n
	Server:\x20Microsoft-IIS/6.0\r\n
	X-Powered-By:\x20ASP.NET\r\n
	Date:\x20Thu,\x2001\x20Oct\x202009\x2013:56:53\x20GMT\r\n
	\r\n
	\r\n
	\r\n
	\r\n
	\r\n
	\r\n
	\xE1,\x20\xE9,\x20\xED,\x20\xF3,\x20\xFA,\x20\xFD\r\n
	\r\n
	

SessionLog for 2nd ReceiveString method call

It is easy to see that the accented characters (á, é, í, ó, ú, ý) are each represented by two bytes in the received data: \xC3\xA1, \xC3\xA9, etc.

ReceiveString1: HTTP/1.1\x20200\x20OK\r\n
	Content-Length:\x20141\r\n
	Content-Type:\x20text/html\r\n
	Last-Modified:\x20Thu,\x2001\x20Oct\x202009\x2012:29:48\x20GMT\r\n
	Accept-Ranges:\x20bytes\r\n
	ETag:\x20\"a6968dd9242ca1:28b\"\r\n
	Server:\x20Microsoft-IIS/6.0\r\n
	X-Powered-By:\x20ASP.NET\r\n
	Date:\x20Thu,\x2001\x20Oct\x202009\x2013:56:53\x20GMT\r\n
	\r\n
	\r\n
	\r\n
	\r\n
	\r\n
	\r\n
	\xC3\xA1,\x20\xC3\xA9,\x20\xC3\xAD,\x20\xC3\xB3,\x20\xC3\xBA,\x20\xC3\xBD\r\n
	\r\n
	

DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSocket
    Boolean iSsl
    Integer iMaxWaitMillisec
    Integer iPort
    String sGetRequest
    String sResp
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    Get Create (RefClass(cComChilkatSocket)) To hoSocket
    If (Not(IsComObjectCreated(hoSocket))) Begin
        Send CreateComObject of hoSocket
    End

    // To demonstrate receiving character (i.e. not binary) data,
    // this example will connect to the chilkatsoft.com web server
    // and download a very short and simple HTML page.
    // (Note: You would typically use the Chilkat HTTP component
    // to communicate with a web server.  We only do it here to
    // provide an example that is runnable such that socket peer
    // (i.e. the other end of the socket connection) is already
    // available.

    // So.. let's first connect the socket to the remote peer.
    Move False To iSsl
    Move 20000 To iMaxWaitMillisec
    Move 80 To iPort
    Get ComConnect Of hoSocket "www.chilkatsoft.com" iPort iSsl iMaxWaitMillisec To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Set maximum timeouts for reading an writing (in millisec)
    Set ComMaxReadIdleMs Of hoSocket To 10000
    Set ComMaxSendIdleMs Of hoSocket To 10000

    // Send a simple HTTP GET request to download 
    // an HTML file on the server named "iso_chars.html"
    // This web page contains the following characters
    // using the iso-8859-1 encoding:
    // á, é, í, ó, ú, ý

    // The Chilkat Socket API has a convenience method named
    // BuildHttpGetRequest to make it easy to send an HTTP GET
    // for a URL:

    Get ComBuildHttpGetRequest Of hoSocket "http://www.chilkatsoft.com/iso_chars.html" To sGetRequest

    // Send the GET request to the HTTP server:
    Get ComSendString Of hoSocket sGetRequest To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Before calling ReceiveString to get the HTTP response,
    // let's turn on session logging so we can examine the 
    // actual bytes received:
    Set ComKeepSessionLog Of hoSocket To True

    // IMPORTANT:
    // Tell the component the character encoding of the string
    // data to be received by setting the StringCharset property.
    // This is extremely important.  The socket component/library must know how
    // to interpret the received bytes.  For example,
    // the character "á" will be represented as a single byte
    // having the hex value 0xE1 when encoded using iso-8859-1,
    // but will arrive as a sequence of 2 bytes having the values
    // 0xC3 0xA1 when encoded using utf-8.
    // Given that strings are returned as Unicode or utf-8 in most
    // programming languages, the socket component must know how
    // to interpret the received bytes to properly construct the 
    // string to be returned to the caller.
    Set ComStringCharset Of hoSocket To "iso-8859-1"

    // OK, get the response:
    Get ComReceiveString Of hoSocket To sResp
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Examine the received string:
    Showln sResp
    Showln "---------------------------"

    // Important: ReceiveString may not receive the entire response.
    // It simply receives whatever data is already available from 
    // the connected peer.  To simplify the example, we're assuming
    // the complete response is received -- and it is likely
    // because the response is short.

    // OK, let's examine the session log to see the actual bytes
    // received.  (The session logging was turned on just
    // before the call to ReceiveBytes, so we won't see the activity
    // prior to it.)
    // The SessionLogEncoding property controls the output format
    // of the session log.  It defaults to "esc" for escaped ASCII, which
    // is a good way of viewing mostly US-ASCII character data.
    // We'll be able to see the binary bytes in between the printable
    // ASCII characters as hex values escaped with "\x".
    Get ComSessionLog Of hoSocket To sTemp1
    Showln sTemp1

    // (Refer to the SessionLog for the 1st ReceiveString above for the expected results.)

    // Close the connection with the server
    // Wait a max of 20 seconds (20000 millsec)
    Get ComClose Of hoSocket 20000 To iSuccess

    // -----------------------------------------------------------------
    // Now we'll download a utf-8 encoded HTML page
    // to see how the bytes received for the same characters
    // are different.  The Socket component must know how
    // to interpret these bytes as characters, and (as discussed
    // before) this is the purpose of the StringCharset property.

    // Connect to the chilkatsoft.com HTTP server again.
    Get ComConnect Of hoSocket "www.chilkatsoft.com" iPort iSsl iMaxWaitMillisec To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // This time, get an HTML page where the characters
    // are encoded using utf-8.
    Get ComBuildHttpGetRequest Of hoSocket "http://www.chilkatsoft.com/utf8_chars.html" To sGetRequest

    // Send the GET request to the HTTP server:
    Get ComSendString Of hoSocket sGetRequest To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Tell the component to interpret the received bytes as
    // utf-8.  (This only applies to methods that receive strings,
    // such as ReceiveString, ReceiveUntilMatch, etc.  
    // Methods that receive bytes, such as ReceiveBytes, do
    // not try to interpret the bytes received from the connected
    // peer -- they simply return the bytes received.)
    Set ComStringCharset Of hoSocket To "utf-8"

    // Clear the session log so we can examine it again for the next
    // call to ReceiveString:
    Send ComClearSessionLog To hoSocket

    Get ComReceiveString Of hoSocket To sResp
    Get ComLastMethodSuccess Of hoSocket To bTemp1
    If (bTemp1 <> True) Begin
        Get ComLastErrorText Of hoSocket To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // The characters should display correctly:
    Showln "---------------------------"
    Showln sResp
    Showln "---------------------------"

    // Examine the session log.  You'll see that the actual bytes
    // received for the characters were 2-bytes/char.  Because
    // the StringCharset was correctly set, the socket component
    // knew how to interpret the bytes to arrive at the appropriate
    // characters.
    Get ComSessionLog Of hoSocket To sTemp1
    Showln sTemp1

    // (Refer to the SessionLog for the 2nd ReceiveString above for the expected results.)

    Get ComClose Of hoSocket 20000 To iSuccess


End_Procedure