Table of Contents

Object Store

The Object Store is very similar to the Key Value Store in that you put and get data using a key. The difference being that Object store allows for the storage of objects that can be of any size.

Under the covers Object Store is a client side construct that allows you to store and retrieve chunks of data by a key using JetStream as the stream persistence engine. It's a simple, yet powerful way to store and retrieve large data like files.

To be able to use Object Store you need to enable JetStream by running the server with -js flag e.g. nats-server -js.

Object Store Quick Start

Download the latest nats-server for your platform and run it with JetStream enabled:

$ nats-server -js

Install NATS.Net from Nuget.

Before we can do anything, we need an Object Store context:

await using var nc = new NatsClient();
var obj = nc.CreateObjectStoreContext();

Let's create our store first. In Object Store, a bucket is simply a storage for key/object pairs:

var store = await obj.CreateObjectStoreAsync("test-bucket");

Now that we have a bucket in our stream, let's see its status using the NATS command line client:

$ nats object ls
╭──────────────────────────────────────────────────────────────────────╮
│                         Object Store Buckets                         │
├─────────────┬─────────────┬─────────────────────┬──────┬─────────────┤
│ Bucket      │ Description │ Created             │ Size │ Last Update │
├─────────────┼─────────────┼─────────────────────┼──────┼─────────────┤
│ test-bucket │             │ 2023-10-18 14:10:27 │ 0 B  │ never       │
╰─────────────┴─────────────┴─────────────────────┴──────┴─────────────╯

We can save objects in a bucket by putting them using a key, which is my/random/data.bin in our case. We can also retrieve the saved value by its key:

await store.PutAsync("my/random/data.bin", File.OpenRead("data.bin"));

await store.GetAsync("my/random/data.bin", File.OpenWrite("data_copy.bin"));

We can also confirm that our value is persisted by using the NATS command line:

$ nats object info test-bucket my/random/data.bin
Object information for test-bucket > my/random/data.bin

               Size: 10 MiB
  Modification Time: 18 Oct 23 14:54 +0000
             Chunks: 80
             Digest: SHA-256 d34334673e4e2b2300c09550faa5e2b6d0f04245a1d0b664454bb922da56

Other Operations

Get Info

We can get information about a key in a bucket:

var metadata = await store.GetInfoAsync("my/random/data.bin");

Console.WriteLine("Metadata:");
Console.WriteLine($"  Bucket: {metadata.Bucket}");
Console.WriteLine($"  Name: {metadata.Name}");
Console.WriteLine($"  Size: {metadata.Size}");
Console.WriteLine($"  Time: {metadata.MTime}");
Console.WriteLine($"  Chunks: {metadata.Chunks}");

Delete

We can delete a key from a bucket:

await store.DeleteAsync("my/random/data.bin");

See the API reference for the full list of Object Store operations.

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