Continuous Queries with the JavaScript Client

What You Will Learn

How to register a continuous query so the server pushes events whenever cache entries join, leave, or are updated relative to an Ickle query result set.

Prerequisites

Node.js 22+
An Infinispan Server running on localhost:11222
The protobufjs npm package (installed via npm install)

Start an Infinispan Server with Docker or Podman:

docker run -it --rm -p 11222:11222 -e USER=admin -e PASS=password quay.io/infinispan/server:latest

Tip	You can replace `docker` with `podman` in the command above if you use Podman.

Note	The `protoStreamCache` is created automatically by the setup script using the admin API.

Step 1: Define a Protobuf Schema

Define an InstaPost schema with a @TypeId annotation:

syntax = "proto3";
package tutorial;
/**
 * @TypeId(1000050)
 */
message InstaPost {
    string id = 1;
    string user = 2;
    string hashtag = 3;
}

const metaClient = await ispn.client(addr, {
    cacheName: '___protobuf_metadata',
    dataFormat: {keyType: 'text/plain', valueType: 'text/plain'},
    authentication: { ... }
});
await metaClient.put('tutorial/InstaPost.proto', instaPostProto);

Step 2: Connect with Protostream Encoding

const client = await ispn.client(addr, {
    cacheName: 'protoStreamCache',
    topologyUpdates: false,
    dataFormat: {
        keyType: 'text/plain',
        valueType: 'application/x-protostream'
    },
    authentication: { ... }
});

client.registerProtostreamRoot(root);
client.registerProtostreamType('.tutorial.InstaPost', 1000050);

Step 3: Register a Continuous Query

const cq = await client.addContinuousQuery(
    'FROM tutorial.InstaPost p WHERE p.user = :userName',
    {params: {userName: 'belen_esteban'}}
);

cq.on('joining', function(key, value) {
    console.log('New matching post detected!');
});

cq.on('leaving', function(key) {
    console.log('Post no longer matches.');
});

cq.on('updated', function(key, value) {
    console.log('Matching post was updated.');
});

The three event types are:

joining — an entry now matches the query (new entry or modified to match)
leaving — an entry no longer matches the query (removed or modified to not match)
updated — an entry still matches but its value changed

Step 4: Remove the Continuous Query

await client.removeContinuousQuery(cq);

Step 5: Run the Tutorial

npm run continuous-query

You should see output showing joining events as random posts by @belen_esteban are detected.

What’s Next

Ickle queries for one-shot query operations
Event listeners for basic cache event listeners