# 流 The first step is to set up storage for our `ORDERS` related messages, these arrive on a wildcard of subjects all flowing into the same Stream and they are kept for 1 year. ## Creating ```shell nats str add ORDERS ``` ``` ? Subjects to consume ORDERS.* ? Storage backend file ? Retention Policy Limits ? Discard Policy Old ? Message count limit -1 ? Message size limit -1 ? Maximum message age limit 1y ? Maximum individual message size [? for help] (-1) -1 Stream ORDERS was created Information for Stream ORDERS Configuration: Subjects: ORDERS.* Acknowledgements: true Retention: File - Limits Replicas: 1 Maximum Messages: -1 Maximum Bytes: -1 Maximum Age: 8760h0m0s Maximum Message Size: -1 Maximum Consumers: -1 Statistics: Messages: 0 Bytes: 0 B FirstSeq: 0 LastSeq: 0 Active Consumers: 0 ``` You can get prompted interactively for missing information as above, or do it all on one command. Pressing `?` in the CLI will help you map prompts to CLI options: ```shell nats str add ORDERS --subjects "ORDERS.*" --ack --max-msgs=-1 --max-bytes=-1 --max-age=1y --storage file --retention limits --max-msg-size=-1 --discard old --dupe-window="0s" --replicas 1 ``` Additionally one can store the configuration in a JSON file, the format of this is the same as `$ nats str info ORDERS -j | jq .config`: ```shell nats str add ORDERS --config orders.json ``` ## Listing We can confirm our Stream was created: ```shell nats str ls ``` ``` Streams: ORDERS ``` ## Querying Information about the configuration of the Stream can be seen, and if you did not specify the Stream like below, it will prompt you based on all known ones: ```shell nats str info ORDERS ``` ``` Information for Stream ORDERS created 2021-02-27T16:49:36-07:00 Configuration: Subjects: ORDERS.* Acknowledgements: true Retention: File - Limits Replicas: 1 Discard Policy: Old Duplicate Window: 2m0s Maximum Messages: unlimited Maximum Bytes: unlimited Maximum Age: 1y0d0h0m0s Maximum Message Size: unlimited Maximum Consumers: unlimited State: Messages: 0 Bytes: 0 B FirstSeq: 0 LastSeq: 0 Active Consumers: 0 ``` Most commands that show data as above support `-j` to show the results as JSON: ```shell nats str info ORDERS -j ``` ```json { "config": { "name": "ORDERS", "subjects": [ "ORDERS.*" ], "retention": "limits", "max_consumers": -1, "max_msgs": -1, "max_bytes": -1, "max_age": 31536000000000000, "max_msg_size": -1, "storage": "file", "discard": "old", "num_replicas": 1, "duplicate_window": 120000000000 }, "created": "2021-02-27T23:49:36.700424Z", "state": { "messages": 0, "bytes": 0, "first_seq": 0, "first_ts": "0001-01-01T00:00:00Z", "last_seq": 0, "last_ts": "0001-01-01T00:00:00Z", "consumer_count": 0 } } ``` This is the general pattern for the entire `nats` utility as it relates to JetStream - prompting for needed information but every action can be run non-interactively making it usable as a CLI API. All information output like seen above can be turned into JSON using `-j`. ## Copying A stream can be copied into another, which also allows the configuration of the new one to be adjusted via CLI flags: ```shell nats str cp ORDERS ARCHIVE --subjects "ORDERS_ARCHIVE.*" --max-age 2y ``` ``` Stream ORDERS was created Information for Stream ORDERS created 2021-02-27T16:52:46-07:00 Configuration: Subjects: ORDERS_ARCHIVE.* Acknowledgements: true Retention: File - Limits Replicas: 1 Discard Policy: Old Duplicate Window: 2m0s Maximum Messages: unlimited Maximum Bytes: unlimited Maximum Age: 2y0d0h0m0s Maximum Message Size: unlimited Maximum Consumers: unlimited State: Messages: 0 Bytes: 0 B FirstSeq: 0 LastSeq: 0 Active Consumers: 0 ``` ## Editing A stream configuration can be edited, which allows the configuration to be adjusted via CLI flags. Here I have an incorrectly created ORDERS stream that I fix: ```shell nats str info ORDERS -j | jq .config.subjects ``` ``` [ "ORDERS.new" ] ``` Change the subjects for the stream ```shell nats str edit ORDERS --subjects "ORDERS.*" ``` ``` Stream ORDERS was updated Information for Stream ORDERS Configuration: Subjects: ORDERS.* .... ``` Additionally, one can store the configuration in a JSON file, the format of this is the same as `$ nats str info ORDERS -j | jq .config`: ```shell nats str edit ORDERS --config orders.json ``` ## Publishing Into a Stream Now let's add some messages to our Stream. You can use `nats pub` to add messages, pass the `--wait` flag to see the publish ack being returned. You can publish without waiting for acknowledgement: ```shell nats pub ORDERS.scratch hello ``` But if you want to be sure your messages got to JetStream and were persisted you can make a request: ```shell nats req ORDERS.scratch hello ``` ``` 13:45:03 Sending request on [ORDERS.scratch] 13:45:03 Received on [_INBOX.M8drJkd8O5otORAo0sMNkg.scHnSafY]: '+OK' ``` Keep checking the status of the Stream while doing this and you'll see its stored messages increase. ```shell nats str info ORDERS ``` ``` Information for Stream ORDERS ... Statistics: Messages: 3 Bytes: 147 B FirstSeq: 1 LastSeq: 3 Active Consumers: 0 ``` After putting some throwaway data into the Stream, we can purge all the data out - while keeping the Stream active: ## Deleting All Data To delete all data in a stream use `purge`: ```shell nats str purge ORDERS -f ``` ``` ... State: Messages: 0 Bytes: 0 B FirstSeq: 1,000,001 LastSeq: 1,000,000 Active Consumers: 0 ``` ## Deleting A Message A single message can be securely removed from the stream: ```shell nats str rmm ORDERS 1 -f ``` ## Deleting Sets Finally, for demonstration purposes, you can also delete the whole Stream and recreate it. Then we're ready for creating the Consumers: ```shell nats str rm ORDERS -f nats str add ORDERS --subjects "ORDERS.*" --ack --max-msgs=-1 --max-bytes=-1 --max-age=1y --storage file --retention limits --max-msg-size=-1 --discard old --dupe-window="0s" --replicas 1 ```