Ability to print to CUPS URL

[paul-cureton]

I am attempting to print ZPL to a CUPS printer URL. The documentation shows:

function printToURL() {
   var config = qz.configs.create({ host: "192.168.254.254", port: 9100 }); // or http://<cups-server>/printers/<my-printer>
   //...
}

I have attempted a few different combinations for the qz.configs.create() function:

• qz.configs.create('http://<cups-server>:<port>/printers/<my-printer>')
• qz.configs.create({host: 'http://<cups-server>/printers/<my-printer>', port: <port>})
• qz.configs.create({host: 'http://<cups-server>:<port>/printers/<my-printer>'})

Regardless of how I create the config, I get a java.net.UnknownHostException.

I can successfully print (same payload) with the alternatePrinting: true option as well as using a RAW socket instead of a CUPS URI. The CUPS server requires no authentication, and I have verified it works both locally and remotely. The CUPS queue is configured as a raw queue.

Here a log of an attempt, with my network IPs and queue names removed:

[DEBUG] 2018-11-20 10:59:28,054 @ qz.ws.PrintSocketClient:?
	Message: {"call":"print","promise":{},"params":{"printer":{"name":"http://<cups-server>:<port>/printers/<printer-name>"},"options":{"colorType":"color","copies":1,"density":0,"duplex":false,"fallbackDensity":null,"interpolation":"bicubic","jobName":null,"legacy":false,"margins":0,"orientation":null,"paperThickness":null,"printerTray":null,"rasterize":true,"rotation":0,"scaleContent":true,"size":null,"units":"in","altPrinting":false,"encoding":null,"endOfDoc":null,"perSpool":1},"data":["^XA\n","^FO50,100",{"type":"raw","format":"image","data":"https://demo.qz.io/assets/img/image_sample_bw.png","options":{"language":"ZPLII"}},"^FS\n","^FO50,300^ADN,36,20^FDPRINTED USING^FS\n","^FO50,350^ADN,36,20^FDQZ-TRAY ^FS\n","^FO50,400^ADN,36,20^FDVERSION 2.0.7^FS\n\n","^XZ\n"]},"timestamp":1542733168049,"uid":"aedjz5","position":{"x":960,"y":540}}
[WARN] 2018-11-20 10:59:28,056 @ qz.ws.PrintSocketClient:?
	Bad signature on request
[DEBUG] 2018-11-20 10:59:28,066 @ qz.common.TrayManager:?
	Calculated dialog centered at: java.awt.Point[x=649,y=467]
[INFO] 2018-11-20 10:59:29,854 @ qz.common.TrayManager:?
	Allowed localhost to print to http://<cups-server>:<port>/printers/<printer-name>
[TRACE] 2018-11-20 10:59:29,855 @ qz.utils.PrintingUtilities:?
	Waiting for processor, 0/1 already in use
[DEBUG] 2018-11-20 10:59:29,857 @ qz.utils.PrintingUtilities:?
	Using qz.printer.action.PrintRaw to print
[DEBUG] 2018-11-20 10:59:29,858 @ qz.printer.PrintServiceMatcher:?
	Searching for PrintService matching http://<cups-server>:<port>/printers/<printer-name>
[DEBUG] 2018-11-20 10:59:29,858 @ qz.printer.PrintServiceMatcher:?
	Found 3 printers
[WARN] 2018-11-20 10:59:29,859 @ qz.printer.PrintServiceMatcher:?
	Printer not found: http://<cups-server>:<port>/printers/<printer-name>
[ERROR] 2018-11-20 10:59:29,859 @ qz.utils.PrintingUtilities:?
	Failed to print
java.lang.IllegalArgumentException: Cannot find printer with name "http://<cups-server>:<port>/printers/<printer-name>"
	at qz.printer.PrintOutput.<init>(Unknown Source)
	at qz.utils.PrintingUtilities.processPrintRequest(Unknown Source)
	at qz.ws.PrintSocketClient.processMessage(Unknown Source)
	at qz.ws.PrintSocketClient.onMessage(Unknown Source)
	at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
	at java.lang.reflect.Method.invoke(Method.java:508)
	at org.eclipse.jetty.websocket.common.events.annotated.CallableMethod.call(CallableMethod.java:70)
	at org.eclipse.jetty.websocket.common.events.annotated.OptionalSessionCallableMethod.call(OptionalSessionCallableMethod.java:68)
	at org.eclipse.jetty.websocket.common.events.JettyAnnotatedEventDriver$2.run(JettyAnnotatedEventDriver.java:210)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555)
	at java.lang.Thread.run(Thread.java:812)
[TRACE] 2018-11-20 10:59:29,863 @ qz.utils.PrintingUtilities:?
	Returning processor back to pool

[paul-cureton]

Here is another log using a different qz.configs.create() call:

[DEBUG] 2018-11-20 11:09:09,769 @ qz.ws.PrintSocketClient:?
	Message: {"call":"print","promise":{},"params":{"printer":{"host":"http://<cups-server>/printers/<my-printer>","port":<port>},"options":{"colorType":"color","copies":1,"density":0,"duplex":false,"fallbackDensity":null,"interpolation":"bicubic","jobName":null,"legacy":false,"margins":0,"orientation":null,"paperThickness":null,"printerTray":null,"rasterize":true,"rotation":0,"scaleContent":true,"size":null,"units":"in","altPrinting":false,"encoding":null,"endOfDoc":null,"perSpool":1},"data":["^XA\n","^FO50,100",{"type":"raw","format":"image","data":"https://demo.qz.io/assets/img/image_sample_bw.png","options":{"language":"ZPLII"}},"^FS\n","^FO50,300^ADN,36,20^FDPRINTED USING^FS\n","^FO50,350^ADN,36,20^FDQZ-TRAY ^FS\n","^FO50,400^ADN,36,20^FDVERSION 2.0.7^FS\n\n","^XZ\n"]},"timestamp":1542733749765,"uid":"f28b2w","position":{"x":960,"y":540}}
[WARN] 2018-11-20 11:09:09,772 @ qz.ws.PrintSocketClient:?
	Bad signature on request
[DEBUG] 2018-11-20 11:09:09,782 @ qz.common.TrayManager:?
	Calculated dialog centered at: java.awt.Point[x=680,y=467]
[INFO] 2018-11-20 11:09:11,640 @ qz.common.TrayManager:?
	Allowed localhost to print to http://<cups-server>/printers/<my-printer>
[TRACE] 2018-11-20 11:09:11,640 @ qz.utils.PrintingUtilities:?
	Waiting for processor, 0/1 already in use
[DEBUG] 2018-11-20 11:09:11,641 @ qz.utils.PrintingUtilities:?
	Using qz.printer.action.PrintRaw to print
[WARN] 2018-11-20 11:09:11,641 @ qz.printer.PrintOptions:?
	Cannot read null as a double for fallbackDensity, using default
[INFO] 2018-11-20 11:09:11,949 @ qz.printer.ImageWrapper:?
	Loading BufferedImage
[INFO] 2018-11-20 11:09:11,950 @ qz.printer.ImageWrapper:?
	Dimensions: 256x128
[INFO] 2018-11-20 11:09:11,951 @ qz.printer.ImageWrapper:?
	Initializing Image Fields
[INFO] 2018-11-20 11:09:11,952 @ qz.printer.ImageWrapper:?
	Converting image to monochrome
[INFO] 2018-11-20 11:09:11,982 @ qz.printer.ImageWrapper:?
	Packing bits
[DEBUG] 2018-11-20 11:09:11,991 @ qz.printer.action.PrintRaw:?
	Printing to host http://<cups-server>/printers/<my-printer>
[ERROR] 2018-11-20 11:09:12,002 @ qz.utils.PrintingUtilities:?
	Failed to print
javax.print.PrintException: java.net.UnknownHostException: http://<cups-server>/printers/<my-printer>
	at qz.printer.action.PrintRaw.print(Unknown Source)
	at qz.utils.PrintingUtilities.processPrintRequest(Unknown Source)
	at qz.ws.PrintSocketClient.processMessage(Unknown Source)
	at qz.ws.PrintSocketClient.onMessage(Unknown Source)
	at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
	at java.lang.reflect.Method.invoke(Method.java:508)
	at org.eclipse.jetty.websocket.common.events.annotated.CallableMethod.call(CallableMethod.java:70)
	at org.eclipse.jetty.websocket.common.events.annotated.OptionalSessionCallableMethod.call(OptionalSessionCallableMethod.java:68)
	at org.eclipse.jetty.websocket.common.events.JettyAnnotatedEventDriver$2.run(JettyAnnotatedEventDriver.java:210)
	at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:635)
	at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:555)
	at java.lang.Thread.run(Thread.java:812)
Caused by: java.net.UnknownHostException: http://<cups-server>/printers/<my-printer>
	at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:214)
	at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:403)
	at java.net.Socket.connect(Socket.java:666)
	at java.net.Socket.connect(Socket.java:606)
	at java.net.Socket.<init>(Socket.java:469)
	at java.net.Socket.<init>(Socket.java:239)
	at qz.printer.action.PrintRaw.printToHost(Unknown Source)
	... 13 more
[TRACE] 2018-11-20 11:09:12,007 @ qz.utils.PrintingUtilities:?
	Returning processor back to pool

[tresf]

Correct, this is not supported.

The underlying Java Socket implementation that is used does not provide support for HTTP endpoints.

tray/src/qz/printer/action/PrintRaw.java

Lines 214 to 228 in 8f2e617

	/**
	* A brute-force, however surprisingly elegant way to send a file to a networked printer.
	* <p/>
	* Please note that this will completely bypass the Print Spooler,
	* so the Operating System will have absolutely no printer information.
	* This is printing "blind".
	*/
	private void printToHost(String host, int port, byte[] cmds) throws IOException {
	log.debug("Printing to host {}:{}", host, port);
	//throws any exception and auto-closes socket and stream
	try(Socket socket = new Socket(host, port); DataOutputStream out = new DataOutputStream(socket.getOutputStream())) {
	out.write(cmds);
	}
	}

In this case host is a network address as defined by either a resolvable hostname or an IP4/IP6 style address. It's a raw socket and because of that, the standard routing you'd expect from a full blown web server is naturally invalid by context.

To properly support URLs we would need to add URL support to the API. Here's an example from Oracle:

import java.net.*;
import java.io.*;

public class URLConnectionReader {
    public static void main(String[] args) throws Exception {
        URL oracle = new URL("http://www.oracle.com/");
        URLConnection yc = oracle.openConnection();
        BufferedReader in = new BufferedReader(new InputStreamReader(
                                    yc.getInputStream()));
        String inputLine;
        while ((inputLine = in.readLine()) != null) 
            System.out.println(inputLine);
        in.close();
    }
}

The API would have to change slightly, we'd need to expand the printer to accept a URL. e.g.

var config = qz.configs.create({ url: "http://path/to/some/endpoint", port: 9100 });

[tresf]

@arpaulnet hi, I'm not sure if you're still actively using QZ Tray, but if so, do you mind testing the new socket feature for this purpose? #750