- Hazelcast Node.js Client
- Features
- Installing the Client
- Using the Client
- Serialization Considerations
- Development
- Testing
- Release Notes
- Mail Group
- License
- Copyright
NOTE: This project is currently in active development.
This document explains Node.js client for Hazelcast which uses Hazelcast's Open Client Protocol 1.6. This client works with Hazelcast 3.6 and higher.
Hazelcast is a clustering and highly scalable data distribution platform. With its various distributed data structures, distributed caching capabilities, elastic nature and more importantly with so many happy users, Hazelcast is a feature-rich, enterprise-ready and developer-friendly in-memory data grid solution.
Hazelcast Node.js client supports the following data structures and features:
- Map
- Queue
- Set
- List
- Multi Map
- Replicated Map
- Ringbuffer
- Reliable Topic
- Near Cache support for Map
- Lock
- Semaphore
- Atomic Long
- Flake Id Generator
- Fast Aggregations
- CRDT Counter
- Event Listeners
- Entry Processors
- Predicates
- Smart Client
- Unisocket Client
- Hazelcast Native Serialization
- Lifecycle Service
- SSL connection support (requires enterprise server)
Following command installs Hazelcast Node.js client:
npm install hazelcast-client --save
Hazelcast Node.js Client connects to a Hazelcast IMDG cluster. See https://hazelcast.org/download/.
Following script illustrates a basic example in which a map is created in Hazelcast Node.js client and an entry is added to that map:
var HazelcastClient = require('hazelcast-client').Client;
var person = {
firstName: "Joe",
lastName: "Doe",
age: 42
};
var map;
HazelcastClient.newHazelcastClient().then(function (hazelcastClient) {
map = hazelcastClient.getMap("personMap");
map.put(1, person).then(function (val) {
// prints previous value for key `1`
console.log(val);
});
map.get(1).then(function (value) {
console.log(value);
})
});
Please see Hazelcast Node.js code samples for more examples.
You can also refer to Hazelcast Node.js API Documentation.
You can configure Hazelcast Node.js Client declaratively (JSON) or programmatically (API).
See CONFIG.md for details.
Hazelcast needs to serialize objects in order to be able to keep them in the server memory. For primitive types, it uses Hazelcast native serialization. For other complex types (e.g. JS objects), it uses JSON serialization.
For example, when you try to query your data using predicates, this querying is handled on the server side so Hazelcast does not have to bring all data to the client but only the relevant entries. Otherwise, there would be a lot of unneccessary data traffic between the client and the server and the performance would severely drop. Because predicates run on the server side, the server should be able to reason about your objects. That is why you need to implement serialization on the server side.
The same applies to MapStore. The server should be able to deserialize your objects in order to store them in MapStore.
Regarding arrays in a serializable object, you can use methods like writeIntArray
if the array is of a primitive type.
If you have nested objects, these nested objects also need to be serializable. Register the serializers for nested objects and the method writeObject
will not have any problem with finding a suitable serializer for and writing/reading the nested object.
If you have arrays of custom objects, you can serialize/deserialize them like the following:
writeData(dataOutput) {
...
dataOutput.writeInt(this.arrayOfCustomObjects);
this.arrayOfCustomObjects.forEach(function(element) {
dataOutput.writeObject(element);
});
...
}
readData(dataInput) {
...
var arrayOfCustomObjects = [];
var lenOfArray = dataInput.readInt();
for (i=0;i<lenOfArray;i++) {
arrayOfCustomObjects.push(dataInput.readObject());
}
this.arrayOfCustomObjects = arrayOfCustomObjects;
...
}
Follow the below steps to build and install Hazelcast Node.js client from its source:
- Clone the GitHub repository https://github.com/hazelcast/hazelcast-nodejs-client.git.
- Install the dependencies using the command
npm install
. - Compile TypeScript using the command
npm run compile
. - Link the package locally using the command
npm link
. - Run static analysis tool using the command
npm run lint
- Change directory to the project directory.
- Use a locally linked module:
npm link hazelcast-client
. - Tryout the example shown in Using the Client section.
-
Maven
Maven automatically downloads hazelcast-remote-controller and hazelcast from maven repository.
Following command starts the tests:
npm test
You can see the release notes for each release on the Releases page.
Please join the mail group if you are interested in using or developing Hazelcast.
http://groups.google.com/group/hazelcast
Hazelcast is available under the Apache 2 License. Please see the Licensing appendix for more information.
Copyright (c) 2008-2018, Hazelcast, Inc. All Rights Reserved.
Visit www.hazelcast.com for more information.