DEPRECATED!

A windows service has its own limitation:

When using LocalSystem logon

• all users local and network printers can be listed correctly
• cannot print to network printers.

When using NetworkService logon

• only local printers can be listed
• can print to network printers

When using specific user logon

• only local and network printers that are registered by the user can be listed
• can print to network printers which the user has privilege
• a lot of effort to change logon

CONCLUSION: I moved this project to system tray mode, which starts whenever an user sign in. So every users can have their own set of printers.

Raw Printing HTTP Service

A Windows service which serve HTTP protocol to send binary data from browser (javascript) to client local printer. It supports ESC/POS codes and works well with Generic/Text Only Driver. It supports all browser that has XHR implementation.

Configurations

Config file will be in the same directory you install the service named config.json. parameters :

• allowedDomains: string[] => list of allowed origin domains (please include protocol & port)
• port: int => port number to listen (default: 9100)

example :

{
    "allowedDomains": [
        "http://localhost:4200",
        "http://localhost:3000"
    ],
    "port": 9100
}

Paths :

• GET / => view current status of the server and remove already allowed domains via GUI response :

  • type: html

• GET /printers => list all printers available at current machine. HTTP request header origin must be within allowed domains.

  response :

  • type: json
  • values:
    • machineName: string => NetBIOS resolved computer name
    • printers: string[] => list of printer names installed locally
  • example : { "machineName" : "Somebody-PC", "printers" : ["Microsoft XPS Document Writer", "Fax"] }

• GET /permissions => ask local user permission to allow requested domain to print

  query parameters :

  • h: string (required) => domain origin that will be allowed to print which include protocol & port (URI encoded). e.g.: http%3A%2F%2Flocalhost%3A4200

  response :

  • type: html
  • description: dialog with 2 buttons, allow and block

• POST /permissions => add/remove allowed domain origin to print

  accept: json

  body parameters :

  • host: string (required) => domain origin that will be allowed to print which include protocol & port. e.g.: http://localhost:4200
  • status: string (required) => valid status values :
    • allow
    • remove

  response :

  • type: html
  • description: script to close allow origin dialog opened at GET /permission

• POST / => send print job information to printer

  accept: json

  body parameters :

  • printer: string (required) => printer name
  • data: string (required) => base64 encoded binary data
  • id: string (required) => document id/print job name

  response :

  • type: json
  • values:
    • success: boolean => print job sent status
    • data: string => document id/print job name if success or error message if failed

  example : { "printer": "LX-300+", "data": "SGVsbG8gV29ybGQh", "id": "Test Document" }

Notes

• For network printer, you must install it locally first (drivers & authentication)
• You can use esc-pos-encoder to generate binary data (works with either Node.js or browser)

Usage

Angular + esc-pos-encoder:

@Component({
  selector: 'app-root',
  template: `
      <div *ngIf="message">{{message}}</div>
      <button (click)="print()">Print</button>
  `})
class AppComponent {
  message: string;
  constructor(private http: HttpClient) {}
  print() {
    // Generate the document to print
    let encoder = new EscPosEncoder();
    let result = encoder
      .initialize()
      .text('The quick brown fox jumps over the lazy dog')
      .newline()
      .encode();
    let docId = 'Test Document';
    
    // Convert UInt8Array to base64 string
    let buf = Buffer.from(result.buffer);
    let binData = buf.toString('base64');
    
    // Send print job to printer
    this.http.post('http://localhost:9100', {printer: 'LX-300', data: binData, id: docId})
      .subscribe((response) => {
        if (response.success) {
          this.message = 'Print job sent successfully';
        } else {
          this.message = response.data;
        }
      }, (err) => {
        // If failed, ask for print permission
        let winOpt = 'toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=yes,resizable=yes,width=400,height=300,top=0,left=0';
        window.open('http://localhost:9100/permissions?h=http%3A%2F%2Flocalhost%3A4200', 'Ask Permission', winOpt);
      });
  }
}

Credits

Michael Davies