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Chapter 2. Using Hot Rod JS clients

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Take a look at some examples for using the Hot Rod JS client with Data Grid.

2.1. Hot Rod JS client examples

After you install and configure your Hot Rod JS client, start using it by trying out some basic cache operations before moving on to more complex interactions with Data Grid.

2.1.1. Hello world

Create a cache named "myCache" on Data Grid Server then add and retrieve an entry. 

var infinispan = require('infinispan');

// Connect to Data Grid Server.
// Use an existing cache named "myCache".
var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'},
  {
    cacheName: 'myCache',
    clientIntelligence: 'BASIC',
    authentication: {
      enabled: true,
      saslMechanism: 'DIGEST-MD5',
      userName: 'username',
      password: 'changeme'
    }
  }
);

connected.then(function (client) {

  console.log('Connected to `myCache`');

  // Add an entry to the cache.
  var clientPut = client.put('hello', 'world');

  // Retrieve the entry you added.
  var clientGet = clientPut.then(
      function() { return client.get('hello'); });

  // Print the value of the entry.
  var showGet = clientGet.then(
      function(value) { console.log('get(hello)=' + value); });

  // Disconnect from Data Grid Server.
  return client.disconnect();

}).catch(function(error) {

  // Log any errors.
  console.log("Got error: " + error.message);

});

2.1.2. Working with entries and retrieving cache statistics

Add, retrieve, remove single entries and view statistics for the cache. 

var infinispan = require('infinispan');

var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'},
  {
    cacheName: 'myCache',
    authentication: {
        enabled: true,
        saslMechanism: 'DIGEST-MD5',
        userName: 'username',
        password: 'changeme'
    }
  }
);

connected.then(function (client) {

  var clientPut = client.put('key', 'value');

  var clientGet = clientPut.then(
      function() { return client.get('key'); });

  var showGet = clientGet.then(
      function(value) { console.log('get(key)=' + value); });

  var clientRemove = showGet.then(
      function() { return client.remove('key'); });

  var showRemove = clientRemove.then(
      function(success) { console.log('remove(key)=' + success); });

  var clientStats = showRemove.then(
    function() { return client.stats(); });

  var showStats = clientStats.then(
    function(stats) {
      console.log('Number of stores: ' + stats.stores);
      console.log('Number of cache hits: ' + stats.hits);
      console.log('All statistics: ' + JSON.stringify(stats, null, " "));
    });

  return showStats.finally(
      function() { return client.disconnect(); });

}).catch(function(error) {

  console.log("Got error: " + error.message);

});

2.1.3. Working with multiple cache entries

Create multiple cache entries with simple recursive loops. 

var infinispan = require('infinispan');

var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'},
  {
    cacheName: 'myCache',
    authentication: {
        enabled: true,
        saslMechanism: 'DIGEST-MD5',
        userName: 'username',
        password: 'changeme'
    }
  }
);

connected.then(function (client) {
  var data = [
    {key: 'multi1', value: 'v1'},
    {key: 'multi2', value: 'v2'},
    {key: 'multi3', value: 'v3'}];

  var clientPutAll = client.putAll(data);

  var clientGetAll = clientPutAll.then(
    function() { return client.getAll(['multi2', 'multi3']); });

  var showGetAll = clientGetAll.then(
    function(entries) {
      console.log('getAll(multi2, multi3)=%s', JSON.stringify(entries));
    }
  );

  var clientIterator = showGetAll.then(
    function() { return client.iterator(1); });

  var showIterated = clientIterator.then(
    function(it) {
      function loop(promise, fn) {
        // Simple recursive loop over the iterator's next() call.
        return promise.then(fn).then(function (entry) {
          return entry.done
            ? it.close().then(function () { return entry.value; })
            : loop(it.next(), fn);
        });
      }

      return loop(it.next(), function (entry) {
        console.log('iterator.next()=' + JSON.stringify(entry));
        return entry;
      });
    }
  );

  var clientClear = showIterated.then(
    function() { return client.clear(); });

  return clientClear.finally(
    function() { return client.disconnect(); });

}).catch(function(error) {

  console.log("Got error: " + error.message);

});

2.1.4. Using Async and Await constructs

Node.js provides async and await constructs that can simplify cache operations.

Single cache entries

const infinispan = require("infinispan");

const log4js = require('log4js');
log4js.configure('example-log4js.json');

async function test() {
  await new Promise((resolve, reject) => setTimeout(() => resolve(), 1000));
  console.log('Hello, World!');

  let client = await infinispan.client({port: 11222, host: '127.0.0.1'});
  console.log(`Connected to Infinispan dashboard data`);

  await client.put('key', 'value');

  let value = await client.get('key');
  console.log('get(key)=' + value);

  let success = await client.remove('key');
  console.log('remove(key)=' + success);

  let stats = await client.stats();
  console.log('Number of stores: ' + stats.stores);
  console.log('Number of cache hits: ' + stats.hits);
  console.log('All statistics: ' + JSON.stringify(stats, null, " "));

  await client.disconnect();
}

test();

Multiple cache entries

const infinispan = require("infinispan");

const log4js = require('log4js');
log4js.configure('example-log4js.json');

async function test() {
  let client = await infinispan.client({port: 11222, host: '127.0.0.1'});
  console.log(`Connected to Infinispan dashboard data`);

  let data = [
    {key: 'multi1', value: 'v1'},
    {key: 'multi2', value: 'v2'},
    {key: 'multi3', value: 'v3'}];

  await client.putAll(data);

  let entries = await client.getAll(['multi2', 'multi3']);
  console.log('getAll(multi2, multi3)=%s', JSON.stringify(entries));

  let iterator = await client.iterator(1);

  let entry = {done: true};

  do {
    entry = await iterator.next();
    console.log('iterator.next()=' + JSON.stringify(entry));
  } while (!entry.done);

  await iterator.close();

  await client.clear();

  await client.disconnect();
}

test();

2.1.5. Running server-side scripts

You can add custom scripts to Data Grid Server and then run them from Hot Rod JS clients.

Sample script

// mode=local,language=javascript,parameters=[k, v],datatype='text/plain; charset=utf-8'
cache.put(k, v);
cache.get(k);

Script execution

var infinispan = require('infinispan');
var readFile = Promise.denodeify(require('fs').readFile);

var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'}
  {
    // Configure client connections with authentication and encryption here.
  }
);

connected.then(function (client) {

  var addScriptFile = readFile('sample-script.js').then(
    function(file) {
      return client.addScript('sample-script', file.toString());
    });

  var clientExecute = addScriptFile.then(
    function() {
      return client.execute('sample-script', {k: 'exec-key', v: 'exec-value'});
    });

  var showExecute = clientExecute.then(
    function(ret) { console.log('Script execution returned: ' + ret); });

  return showExecute.finally(
    function() { return client.disconnect(); });

}).catch(function(error) {

  console.log("Got error: " + error.message);

});

2.1.6. Registering event listeners

Event listeners notify Hot Rod JS clients when cache updates occur, including when entries are created, modified, removed, or expired.

Note

Events for entry creation and modification notify clients about keys and values. Events for entry removal and expiration notify clients about keys only.

Event listener registration

var infinispan = require('infinispan');

var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'}
  {
    // Configure client connections with authentication and encryption here.
  }
);

connected.then(function (client) {

    var clientAddListenerCreate = client.addListener('create', onCreate);

    var clientAddListeners = clientAddListenerCreate.then(
        function(listenerId) {
            // Associate multiple callbacks with a single client-side listener.
            // To do this, register listeners with the same listener ID.
            var clientAddListenerModify =
                client.addListener('modify', onModify, {listenerId: listenerId});

            var clientAddListenerRemove =
                client.addListener('remove', onRemove, {listenerId: listenerId});

            return Promise.all([clientAddListenerModify, clientAddListenerRemove]);
        });

    var clientCreate = clientAddListeners.then(
        function() { return client.putIfAbsent('eventful', 'v0'); });

    var clientModify = clientCreate.then(
        function() { return client.replace('eventful', 'v1'); });

    var clientRemove = clientModify.then(
        function() { return client.remove('eventful'); });

    var clientRemoveListener =
        Promise.all([clientAddListenerCreate, clientRemove]).then(
            function(values) {
                var listenerId = values[0];
                return client.removeListener(listenerId);
            });

    return clientRemoveListener.finally(
        function() { return client.disconnect(); });

}).catch(function(error) {

    console.log("Got error: " + error.message);

});

function onCreate(key, version) {
    console.log('[Event] Created key: ' + key +
        ' with version: ' + JSON.stringify(version));
}

function onModify(key, version) {
    console.log('[Event] Modified key: ' + key +
        ', version after update: ' + JSON.stringify(version));
}

function onRemove(key) {
    console.log('[Event] Removed key: ' + key);
}

You can tune notifications from event listeners to avoid unnecessary roundtrips with the key-value-with-previous-converter-factory converter. This allows you to, for example, find out values associated with keys within the event instead of retrieving them afterwards.

Remote event converter

var infinispan = require('infinispan');

var connected = infinispan.client(
    {port: 11222, host: '127.0.0.1'}
    , {
        dataFormat : {
            keyType: 'application/json',
            valueType: 'application/json'
        }
    }
);

connected.then(function (client) {
    // Include the remote event converter to avoid unnecessary roundtrips.
    var opts = {
        converterFactory : {
            name: "key-value-with-previous-converter-factory"
        }
    };

    var clientAddListenerCreate = client.addListener('create', logEvent("Created"), opts);

    var clientAddListeners = clientAddListenerCreate.then(
        function(listenerId) {
            // Associate multiple callbacks with a single client-side listener.
            // To do this, register listeners with the same listener ID.
            var clientAddListenerModify =
                client.addListener('modify', logEvent("Modified"), {opts, listenerId: listenerId});

            var clientAddListenerRemove =
                client.addListener('remove', logEvent("Removed"), {opts, listenerId: listenerId});

            return Promise.all([clientAddListenerModify, clientAddListenerRemove]);
        });

    var clientCreate = clientAddListeners.then(
        function() { return client.putIfAbsent('converted', 'v0'); });

    var clientModify = clientCreate.then(
        function() { return client.replace('converted', 'v1'); });

    var clientRemove = clientModify.then(
        function() { return client.remove('converted'); });

    var clientRemoveListener =
        Promise.all([clientAddListenerCreate, clientRemove]).then(
            function(values) {
                var listenerId = values[0];
                return client.removeListener(listenerId);
            });

    return clientRemoveListener.finally(
        function() { return client.disconnect(); });

}).catch(function(error) {

    console.log("Got error: " + error.message);

});

function logEvent(prefix) {
    return function(event) {
        console.log(prefix + " key: " + event.key);
        console.log(prefix + " value: " + event.value);
        console.log(prefix + " previous value: " + event.prev);
    }
}

Tip

You can add custom converters to Data Grid Server. See the Data Grid documentation for information.

2.1.7. Using conditional operations

The Hot Rod protocol stores metadata about values in Data Grid. This metadata provides a deterministic factor that lets you perform cache operations for certain conditions. For example, if you want to replace the value of a key if the versions do not match.

Use the getWithMetadata method to retrieve metadata associated with the value for a key. 

var infinispan = require('infinispan');

var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'}
  {
    // Configure client connections with authentication and encryption here.
  }
);

connected.then(function (client) {

  var clientPut = client.putIfAbsent('cond', 'v0');

  var showPut = clientPut.then(
      function(success) { console.log(':putIfAbsent(cond)=' + success); });

  var clientReplace = showPut.then(
      function() { return client.replace('cond', 'v1'); } );

  var showReplace = clientReplace.then(
      function(success) { console.log('replace(cond)=' + success); });

  var clientGetMetaForReplace = showReplace.then(
      function() { return client.getWithMetadata('cond'); });

  // Call the getWithMetadata method to retrieve the value and its metadata.
  var clientReplaceWithVersion = clientGetMetaForReplace.then(
      function(entry) {
        console.log('getWithMetadata(cond)=' + JSON.stringify(entry));
        return client.replaceWithVersion('cond', 'v2', entry.version);
      }
  );

  var showReplaceWithVersion = clientReplaceWithVersion.then(
      function(success) { console.log('replaceWithVersion(cond)=' + success); });

  var clientGetMetaForRemove = showReplaceWithVersion.then(
      function() { return client.getWithMetadata('cond'); });

  var clientRemoveWithVersion = clientGetMetaForRemove.then(
      function(entry) {
        console.log('getWithMetadata(cond)=' + JSON.stringify(entry));
        return client.removeWithVersion('cond', entry.version);
      }
  );

  var showRemoveWithVersion = clientRemoveWithVersion.then(
      function(success) { console.log('removeWithVersion(cond)=' + success)});

  return showRemoveWithVersion.finally(
      function() { return client.disconnect(); });

}).catch(function(error) {

  console.log("Got error: " + error.message);

});

2.1.8. Working with ephemeral data

Use the getWithMetadata and size methods expire cache entries. 

var infinispan = require('infinispan');

var connected = infinispan.client(
  {port: 11222, host: '127.0.0.1'}
  {
    // Configure client connections with authentication and encryption here.
  }
);

connected.then(function (client) {

  var clientPutExpiry = client.put('expiry', 'value', {lifespan: '1s'});

  var clientGetMetaAndSize = clientPutExpiry.then(
    function() {
      // Compute getWithMetadata and size in parallel.
      return Promise.all([client.getWithMetadata('expiry'), client.size()]);
    });

  var showGetMetaAndSize = clientGetMetaAndSize.then(
    function(values) {
      console.log('Before expiration:');
      console.log('getWithMetadata(expiry)=' + JSON.stringify(values[0]));
      console.log('size=' + values[1]);
    });

  var clientContainsAndSize = showGetMetaAndSize.then(
    function() {
      sleepFor(1100); // Sleep to force expiration.
      return Promise.all([client.containsKey('expiry'), client.size()]);
    });

  var showContainsAndSize = clientContainsAndSize.then(
    function(values) {
      console.log('After expiration:');
      console.log('containsKey(expiry)=' + values[0]);
      console.log('size=' + values[1]);
    });

  return showContainsAndSize.finally(
    function() { return client.disconnect(); });

}).catch(function(error) {

  console.log("Got error: " + error.message);

});

function sleepFor(sleepDuration){
  var now = new Date().getTime();
  while(new Date().getTime() < now + sleepDuration){ /* Do nothing. */ }
}
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