如何使用C＃实现IPP网关？

Question

I need to develop a Internet Printing Protocol gateway in .Net that will receive the print jobs fired from IOS using the AirPrint client. The gateway will receive the document fired and release it to the print queue. I am able to broadcast my print services using the SDK provided by Apple. However, when I listen on a port to receive network streams of a document, I am not able to detect the end of stream received as the client keeps on sending streams. My guess is we have to read the attributes and respond accordingly, but I have no idea of these attributes. Below is the code that I am currently using:

IPAddress ipAddress = IPAddress.Parse("10.0.0.13");
IPAddress tcpListener = new TcpListener(ipAddress, 631);
tcpListener.Start();
while (true)
{
TcpClient tcpClient = tcpListener.AcceptTcpClient();
byte[] bytes = new byte[2560];
NetworkStream stream = tcpClient.GetStream();

stream.Read(bytes, 0, bytes.Length);
string mstrMessage = Encoding.ASCII.GetString(bytesReceived, 0, bytesReceived.Length);

string Continue = "HTTP/1.1 100 Continue\r\n\r\nHTTP/1.1 200 OK\r\nCache-Control: no-cache\r\nDate: " + dateTime + "\r\nPragma: no-cache\r\nTransfer-Encoding: chunked\r\nContent-Type: application/ipp\r\n\r\nattributes-charset utf-8 attributes-natural-language en-us compression-supported none printer-is-accepting-jobs true document-format-supported application/pdf\r\n\r\n0\r\n";

bytesSent = Encoding.ASCII.GetBytes(mstrResponse);

stream.Write(bytesSent, 0, bytesSent.Length);
}

Answer 1

You should check the stream.Read for the returning value. If it isn't zero you have incoming bytes from the TcpClient :

var bytesLength = 0;
do
{
   bytesLength = stream.Read(bytes, 0, bytes.Length);
   if (bytesLength == 0) return;
}
while(bytesLength > 0);

Answer 2

You need to understand the level of communication. You're not even reading or writing proper IPP messages yet. 100 continue is purley HTTP related.

Even though Apples Spec for AirPrint is not publicly available there's still a lot of information online. In short: AirPrint is based on IPP. As for the supported PDL PDF is a good choice but not the only one. iOS first checks the printers capabilities. It's up to you what kind of (virtual) print-server you offer.

(In case you have a business case and require a remote developer, don't hestitate to contact us.)