Node.js

PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)

See more SCard Examples

Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader.

Note: This functionality was introduced in Chilkat v9.5.0.87.

Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

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

    var scard = new chilkat.SCard();

    //  First establish a context to the PC/SC Resource Manager
    success = scard.EstablishContext("user");
    if (success == false) {
        console.log(scard.LastErrorText);
        return;
    }

    //  First we'll examine the state of all connected readers to see which have smartcards already inserted..
    //  Get JSON containing information about the smartcards currently inserted into readers.
    //  This also includes information about USB security tokens.
    var json = new chilkat.JsonObject();
    success = scard.FindSmartcards(json);
    if (success == false) {
        console.log(scard.LastErrorText);
        return;
    }

    //  When writing this example, I have 3 smart card readers plugged into my system.
    //  One of them has a smart card inserted.
    //  Here's the JSON returned by FindSmartcards...

    //  {
    //    "reader": [
    //      {
    //        "name": "Alcor Micro USB Smart Card Reader 0",
    //        "state": "empty"
    //      },
    //      {
    //        "name": "Generic Smart Card Reader Interface 0",
    //        "state": "present",
    //        "vendorName": "Generic",
    //        "serialNumber": "3230303730383138303030303030303030",
    //        "systemName": "Generic Smart Card Reader Interface 0",
    //        "card": {
    //          "atr": "3BFC180000813180459067464A00641606F2727E00E0",
    //          "windows": {
    //            "miniDriver": "tagliov70px.dll",
    //            "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
    //            "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
    //          }
    //        }
    //      },
    //      {
    //        "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
    //        "state": "empty"
    //      }
    //    ]
    //  }

    json.EmitCompact = false;
    console.log(json.Emit());
    console.log(" ");

    //  We can iterate over the JSON to find the readers with a smart card already inserted..
    var name;
    var sbState = new chilkat.StringBuilder();

    var i = 0;
    var count_i = json.SizeOfArray("reader");
    while (i < count_i) {
        json.I = i;
        name = json.StringOf("reader[i].name");

        sbState.Clear();
        json.StringOfSb("reader[i].state",sbState);

        if (sbState.Contains("present",true) == true) {
            console.log(name + " has a smart card inserted.");
        }
        else {
            console.log(name + " does not have a smart card inserted.");
        }

        i = i+1;
    }

    console.log(" ");

    //  Now let's begin the code to wait for a change (where a smart card gets inserted or removed)

    //  Get the list of all readers.
    var stReaders = new chilkat.StringTable();
    success = scard.ListReaders(stReaders);
    if (success == false) {
        console.log(scard.LastErrorText);
        return;
    }

    //  Show the reader names..
    var numReaders = stReaders.Count;
    i = 0;
    while (i < numReaders) {
        console.log(i + ": " + stReaders.StringAt(i));
        i = i+1;
    }

    //  Sample output from the above loop.
    //  0: Alcor Micro USB Smart Card Reader 0
    //  1: Generic Smart Card Reader Interface 0
    //  2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
    //  

    //  Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
    var json2 = new chilkat.JsonObject();
    success = scard.GetStatusChange(30000,stReaders,json2);
    if (success == false) {
        console.log(scard.LastErrorText);
        return;
    }

    console.log(" ");

    //  Let's see what happened...
    json2.EmitCompact = false;
    console.log(json2.Emit());
    console.log(" ");

    //  This is what json2 contains.
    //  A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
    //  The "numChanged" indicates that one reader's status changed.  
    //  The "changed":true indicates the reader that changed.   The state is now "present".

    //  {
    //    "numChanged": 1,
    //    "reader": [
    //      {
    //        "name": "Alcor Micro USB Smart Card Reader 0",
    //        "changed": false,
    //        "state": "empty"
    //      },
    //      {
    //        "name": "Generic Smart Card Reader Interface 0",
    //        "changed": false,
    //        "state": "present",
    //        "atr": "3BFC180000813180459067464A00641606F2727E00E0"
    //      },
    //      {
    //        "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
    //        "changed": true,
    //        "state": "present",
    //        "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
    //      }
    //    ]
    //  }

    //  Find the reader that changed...
    var changed;
    var state;
    var atr;

    var numChanged = json2.IntOf("numChanged");
    console.log("number of readers with a changed state: " + numChanged);

    i = 0;
    count_i = json2.SizeOfArray("reader");
    while (i < count_i) {
        json2.I = i;
        changed = json2.BoolOf("reader[i].changed");
        if (changed == true) {
            name = json2.StringOf("reader[i].name");
            state = json2.StringOf("reader[i].state");

            console.log("Changed: ");
            console.log("    reader name: " + name);
            console.log("    new state: " + state);

            //  If a card is now in this reader, we should have the ATR of the card..
            if (json2.HasMember("reader[i].atr") == true) {
                atr = json2.StringOf("reader[i].atr");
                console.log("    ATR of card inserted into this reader: " + atr);
            }

        }

        i = i+1;
    }

    //  The output from the above loop:

    //  number of readers with a changed state: 1
    //  Changed: 
    //      reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
    //      new state: present
    //      ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09

    //  Applications should always release the context when finished.
    success = scard.ReleaseContext();
    if (success == false) {
        console.log(scard.LastErrorText);
    }


}

chilkatExample();