# Example

Consider this architecture

![Orders](https://1487470910-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-LqMYcZML1bsXrN3Ezg0%2Fuploads%2Fgit-blob-dedcc17f082fa1e39497c54ed8191b6424ee7792%2Fstreams-and-consumers-75p%20\(1\).png?alt=media)

While it is an incomplete architecture it does show a number of key points:

* Many related subjects are stored in a Stream
* Consumers can have different modes of operation and receive just subsets of the messages
* Multiple Acknowledgement modes are supported

A new order arrives on `ORDERS.received`, gets sent to the `NEW` Consumer who, on success, will create a new message on `ORDERS.processed`. The `ORDERS.processed` message again enters the Stream where a `DISPATCH` Consumer receives it and once processed it will create an `ORDERS.completed` message which will again enter the Stream. These operations are all `pull` based meaning they are work queues and can scale horizontally. All require acknowledged delivery ensuring no order is missed.

All messages are delivered to a `MONITOR` Consumer without any acknowledgement and using Pub/Sub semantics - they are pushed to the monitor.

As messages are acknowledged to the `NEW` and `DISPATCH` Consumers, a percentage of them are Sampled and messages indicating redelivery counts, ack delays and more, are delivered to the monitoring system.

## Example Configuration

[Additional documentation](https://docs.nats.io/~/revisions/FTWMYYvWt52KJd0gQISk/running-a-nats-service/configuration/clustering/jetstream_clustering/administration) introduces the `nats` utility and how you can use it to create, monitor, and manage streams and consumers, but for completeness and reference this is how you'd create the ORDERS scenario. We'll configure a 1 year retention for order related messages:

```bash
nats stream add ORDERS --subjects "ORDERS.*" --ack --max-msgs=-1 --max-bytes=-1 --max-age=1y --storage file --retention limits --max-msg-size=-1 --discard=old
nats consumer add ORDERS NEW --filter ORDERS.received --ack explicit --pull --deliver all --max-deliver=-1 --sample 100
nats consumer add ORDERS DISPATCH --filter ORDERS.processed --ack explicit --pull --deliver all --max-deliver=-1 --sample 100
nats consumer add ORDERS MONITOR --filter '' --ack none --target monitor.ORDERS --deliver last --replay instant
```