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PowerTCP SSL Sockets for .NET |
| Dart.PowerTCP.SslSockets Namespace > Tcp Class : Available Property (Tcp) |
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PowerTCP SSL Sockets for .NET |
| Dart.PowerTCP.SslSockets Namespace > Tcp Class : Available Property (Tcp) |
Gets the amount of data that has been received from the network and is available to be read.
[Visual Basic]
<DescriptionAttribute("Returns the Available property of the Socket instance.")>
<BrowsableAttribute(False)>
Public ReadOnly Property Available As Integer[C#]
[DescriptionAttribute("Returns the Available property of the Socket instance.")]
[BrowsableAttribute(false)]
public int Available {get;}[C++]
[DescriptionAttribute("Returns the Available property of the Socket instance.")]
[BrowsableAttribute(false)]
public: __property int get_Available();[C++/CLI]
[DescriptionAttribute("Returns the Available property of the Socket instance.")]
[BrowsableAttribute(false)]
public:
property int Available {
int get();
}The number of bytes of data that has been received from the network and are available to be read.
When data is received from the network, it is collected in system buffers. The Tcp.Available property contains the amount of bytes of data that has been received. In order to receive the data into a useful data structure such as a string, byte array, or Segment object that you can use within your application you must use the Receive or Tcp.Stream.Read methods. If these methods are not invoked or are seldom invoked, then "back pressure" is exerted at the remote host and packet transmission rates will decrease. If these methods are invoked, the data is received and removed from the system buffers, making room for more data to be received from the network.
The following example demonstrates receiving a chunked response from the server. HTTP 1.1 allows a server to send a "chunked" response. When this occurs, the server will send the headers then a hex value representing the size of the next "chunk". This is continued until all data has been sent. This is a good stream example because it demonstrates both reading until a delimiter is found and reading fixed-size "chunks" of data.
[Visual Basic]
' Connect to HTTP Port
Tcp1.Connect("www.yahoo.com", 80)
' Send GET Request for home page. Be sure to specify HTTP/1.1 and Host
' to get a chunked response.
Dim command As Byte() = System.Text.Encoding.Default.GetBytes("GET / HTTP/1.1" + vbCrLf + "Host:www.yahoo.com" + vbCrLf + vbCrLf)
Tcp1.Stream.Write(command)
' Get the headers by reading until a double CRLF is found.
Dim found As Boolean = False
Dim s As String = Tcp1.Stream.Read(vbCrLf + vbCrLf, 1024, found)
Dim pagedata As String = ""
' Keep receiving data. When all data is sent, the server will close the connection.
Do While Tcp1.Connected
' Get the chunk size by reading until a CRLF is found.
s = Tcp1.Stream.Read(vbCrLf, 1024, found)
' Remove the delimiter
s = s.Trim()
' Make sure s has data
If s <> "" Then
' Convert from string hex to decimal integer.
Dim chunksize As Integer = System.Convert.ToInt32(s, 16)
' The final chunk will have size 0 and does not need to be handled.
If chunksize <> 0 Then
' initialize byte array with chunk size
Dim data(chunksize) As Byte
' Fill the byte array.
Tcp1.Stream.Read(data, True)
' Add to the string
pagedata += System.Text.Encoding.Default.GetString(data)
End If
End If
Loop
' Entire page should be retrieved by this point. Display
Debug.WriteLine(pagedata)
[C#]
// Connect to HTTP Port
tcp1.Connect("www.yahoo.com",
80);
// Send GET Request for home page. Be sure to specify HTTP/1.1 and Host
// to get a chunked response.
byte[] command =
System.Text.Encoding.Default.GetBytes("GET / HTTP/1.1\r\nHost:www.yahoo.com\r\n\r\n");
tcp1.Stream.Write(command);
// Get the headers by reading until a double CRLF is found.
bool found =
false;
string s = tcp1.Stream.Read("\r\n\r\n",
1024, ref found);
string pagedata = "";
// Keep receiving data. When all data is sent, the server will close the connection.
while(tcp1.Connected)
{
// Get the chunk size by reading until a CRLF is found.
s = tcp1.Stream.Read("\r\n", 1024, ref found);
// Remove the delimiter
s = s.Trim();
// Make sure s has data
if(s != "")
{
// Convert from string hex to decimal integer.
int chunksize = System.Convert.ToInt32(s, 16);
// The final chunk will have size 0 and does not need to be handled.
if(chunksize != 0)
{
// initialize byte array with chunk size
byte[] data = new
byte[chunksize];
// Fill the byte array.
tcp1.Stream.Read(data, true);
// Add to the string
pagedata+= System.Text.Encoding.Default.GetString(data);
}
}
}
// Entire page should be retrieved at this point. Display
Debug.WriteLine(pagedata);
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
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Documentation version 1.1.2.0.
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