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new 4483cad59 docs: add a consumer group sample to the Node quick start
(#129)
4483cad59 is described below
commit 4483cad594a2a0d0848f587d12122ed8b025c112
Author: Justin Mclean <[email protected]>
AuthorDate: Tue Oct 6 18:05:34 2026 +1100
docs: add a consumer group sample to the Node quick start (#129)
Adds a runnable consumer group sample to the Node quick start, and a
short section on what each sample does when it is run again. All three
samples were run and rerun against apache-iggy 0.10.0 and
apache/iggy:0.9.0.
Co-authored-by: Justin Mclean <[email protected]>
Co-authored-by: Kranti Parisa <[email protected]>
---
content/docs/sdk/node/intro.mdx | 53 ++++++++++++++++++++++++++++++++++++++++-
1 file changed, 52 insertions(+), 1 deletion(-)
diff --git a/content/docs/sdk/node/intro.mdx b/content/docs/sdk/node/intro.mdx
index 5226b2eaa..ac200fc10 100644
--- a/content/docs/sdk/node/intro.mdx
+++ b/content/docs/sdk/node/intro.mdx
@@ -32,7 +32,7 @@ cargo run --bin iggy-server -- --fresh
--with-default-root-credentials
The environment variables make the server reachable through the published port
(it binds to `127.0.0.1` inside the container by default) and set the root
credentials the samples log in with. Without `--with-default-root-credentials`
(or the `IGGY_ROOT_USERNAME` / `IGGY_ROOT_PASSWORD` variables), a first boot
generates a random root password instead of `iggy`/`iggy`. For source runs,
`--fresh` deletes existing local server data. Explicit credential environment
variables take precedence ov [...]
-Save the following snippets as `producer.mjs` and `consumer.mjs` in the
project where you installed the SDK. Run `node producer.mjs` before `node
consumer.mjs`.
+Save the following snippets as `producer.mjs` and `consumer.mjs` in the
project where you installed the SDK. Run `node producer.mjs` before `node
consumer.mjs`. A consumer group sample follows them.
### Producer
@@ -121,6 +121,57 @@ await client.destroy();
The poll response does not wait for the auto-commit to finish. The sample
processes messages after polling, so auto-commit does not confirm that the
application handled each message.
+### Consumer group
+
+A consumer group lets several consumers share a topic. The server assigns
partitions to the members and stores the group's offset. Save this as
`consumer-group.mjs`:
+
+```typescript
+import { Client, PollingStrategy, Consumer } from 'apache-iggy';
+
+const STREAM_NAME = 'sample-stream';
+const TOPIC_NAME = 'sample-topic';
+const GROUP_NAME = 'sample-group';
+
+const client = new Client({
+ transport: 'TCP',
+ options: { port: 8090, host: '127.0.0.1' },
+ credentials: { username: 'iggy', password: 'iggy' },
+});
+
+// Creates the group if it is missing, then joins it.
+const group = await client.group.ensureAndJoin(STREAM_NAME, TOPIC_NAME,
GROUP_NAME);
+
+// The server assigns partitions to each group member, so partitionId is null.
+const polledMessages = await client.message.poll({
+ streamId: STREAM_NAME,
+ topicId: TOPIC_NAME,
+ consumer: Consumer.Group(group.id),
+ partitionId: null,
+ pollingStrategy: PollingStrategy.Next,
+ count: 10,
+ autocommit: true,
+});
+
+for (const message of polledMessages.messages) {
+ const payload = message.payload.toString('utf8');
+ console.log(`Offset: ${message.headers.offset}, Payload: ${payload}`);
+}
+
+await client.destroy();
+```
+
+The group's offset is separate from the single consumer's, so the first run of
`node consumer-group.mjs` reads the topic from offset 0 even after
`consumer.mjs` has run.
+
+### Running the samples again
+
+All three samples can be run again without changes:
+
+- `node producer.mjs` finds the existing stream and topic and appends ten more
messages.
+- `node consumer.mjs` prints only the new messages, because
`PollingStrategy.Next` continues after the stored offset. With nothing new to
read, it prints nothing.
+- `node consumer-group.mjs` does the same from the group's stored offset.
+
+To start again with an empty server, stop the container and run the `docker
run` command again. `--rm` removes the container and its data.
+
## Configuration
The client constructor accepts a few options:
