Client

The Dapr client package allows you to interact with other Dapr applications from a .NET application.

Prerequisites

Building blocks

The .NET SDK allows you to interface with all of the Dapr building blocks.

Invoke a service

You can either use the DaprClient or System.Net.Http.HttpClient to invoke your services.


using var client = new DaprClientBuilder().Build();

// Invokes a POST method named "deposit" that takes input of type "Transaction"
var data = new { id = "17", amount = 99m };
var account = await client.InvokeMethodAsync<object, Account>("routing", "deposit", data, cancellationToken);
Console.WriteLine("Returned: id:{0} | Balance:{1}", account.Id, account.Balance);

var client = DaprClient.CreateInvokeHttpClient(appId: "routing");

var deposit = new Transaction  { Id = "17", Amount = 99m };
var response = await client.PostAsJsonAsync("/deposit", deposit, cancellationToken);
var account = await response.Content.ReadFromJsonAsync<Account>(cancellationToken: cancellationToken);
Console.WriteLine("Returned: id:{0} | Balance:{1}", account.Id, account.Balance);

Save & get application state

var client = new DaprClientBuilder().Build();

var state = new Widget() { Size = "small", Color = "yellow", };
await client.SaveStateAsync(storeName, stateKeyName, state, cancellationToken: cancellationToken);
Console.WriteLine("Saved State!");

state = await client.GetStateAsync<Widget>(storeName, stateKeyName, cancellationToken: cancellationToken);
Console.WriteLine($"Got State: {state.Size} {state.Color}");

await client.DeleteStateAsync(storeName, stateKeyName, cancellationToken: cancellationToken);
Console.WriteLine("Deleted State!");

Query State (Alpha)

var query = "{" +
                "\"filter\": {" +
                    "\"EQ\": { \"value.Id\": \"1\" }" +
                "}," +
                "\"sort\": [" +
                    "{" +
                        "\"key\": \"value.Balance\"," +
                        "\"order\": \"DESC\"" +
                    "}" +
                "]" +
            "}";

var client = new DaprClientBuilder().Build();
var queryResponse = await client.QueryStateAsync<Account>("querystore", query, cancellationToken: cancellationToken);

Console.WriteLine($"Got {queryResponse.Results.Count}");
foreach (var account in queryResponse.Results)
{
    Console.WriteLine($"Account: {account.Data.Id} has {account.Data.Balance}");
}

Publish messages

var client = new DaprClientBuilder().Build();

var eventData = new { Id = "17", Amount = 10m, };
await client.PublishEventAsync(pubsubName, "deposit", eventData, cancellationToken);
Console.WriteLine("Published deposit event!");

Interact with output bindings

using var client = new DaprClientBuilder().Build();

// Example payload for the Twilio SendGrid binding
var email = new 
{
    metadata = new 
    {
        emailTo = "customer@example.com",
        subject = "An email from Dapr SendGrid binding",    
    }, 
    data =  "<h1>Testing Dapr Bindings</h1>This is a test.<br>Bye!",
};
await client.InvokeBindingAsync("send-email", "create", email);

Retrieve secrets


var client = new DaprClientBuilder().Build();

// Retrieve a key-value-pair-based secret - returns a Dictionary<string, string>
var secrets = await client.GetSecretAsync("mysecretstore", "key-value-pair-secret");
Console.WriteLine($"Got secret keys: {string.Join(", ", secrets.Keys)}");

var client = new DaprClientBuilder().Build();

// Retrieve a key-value-pair-based secret - returns a Dictionary<string, string>
var secrets = await client.GetSecretAsync("mysecretstore", "key-value-pair-secret");
Console.WriteLine($"Got secret keys: {string.Join(", ", secrets.Keys)}");

// Retrieve a single-valued secret - returns a Dictionary<string, string>
// containing a single value with the secret name as the key
var data = await client.GetSecretAsync("mysecretstore", "single-value-secret");
var value = data["single-value-secret"]
Console.WriteLine("Got a secret value, I'm not going to be print it, it's a secret!");

Get Configuration Keys (Alpha)

var client = new DaprClientBuilder().Build();

// Retrieve a specific set of keys.
var specificItems = await client.GetConfiguration("configstore", new List<string>() { "key1", "key2" });
Console.WriteLine($"Here are my values:\n{specificItems[0].Key} -> {specificItems[0].Value}\n{specificItems[1].Key} -> {specificItems[1].Value}");

// Retrieve all configuration items by providing an empty list.
var specificItems = await client.GetConfiguration("configstore", new List<string>());
Console.WriteLine($"I got {configItems.Count} entires!");
foreach (var item in configItems)
{
    Console.WriteLine($"{item.Key} -> {item.Value}")
}

Subscribe to Configuration Keys (Alpha)

var client = new DaprClientBuilder().Build();

// The Subscribe Configuration API returns a wrapper around an IAsyncEnumerable<IEnumerable<ConfigurationItem>>.
// Iterate through it by accessing its Source in a foreach loop. The loop will end when the stream is severed
// or if the cancellation token is cancelled.
var subscribeConfigurationResponse = await daprClient.SubscribeConfiguration(store, keys, metadata, cts.Token);
await foreach (var items in subscribeConfigurationResponse.Source.WithCancellation(cts.Token))
{
    foreach (var item in items)
    {
        Console.WriteLine($"{item.Key} -> {item.Value}")
    }
}

Sidecar APIs

Sidecar Health

The .NET SDK provides a way to poll for the sidecar health, as well as a convenience method to wait for the sidecar to be ready.

Poll for health

This health endpoint returns true when both the sidecar and your application are up (fully initialized).

var client = new DaprClientBuilder().Build();

var isDaprReady = await client.CheckHealthAsync();

if (isDaprReady) 
{
    // Execute Dapr dependent code.
}

Poll for health (outbound)

This health endpoint returns true when Dapr has initialized all its components, but may not have finished setting up a communication channel with your application.

This is best used when you want to utilize a Dapr component in your startup path, for instance, loading secrets from a secretstore.

var client = new DaprClientBuilder().Build();

var isDaprComponentsReady = await client.CheckOutboundHealthAsync();

if (isDaprComponentsReady) 
{
    // Execute Dapr component dependent code.
}

Wait for sidecar

The DaprClient also provides a helper method to wait for the sidecar to become healthy (components only). When using this method, it is recommended to include a CancellationToken to allow for the request to timeout. Below is an example of how this is used in the DaprSecretStoreConfigurationProvider.

// Wait for the Dapr sidecar to report healthy before attempting use Dapr components.
using (var tokenSource = new CancellationTokenSource(sidecarWaitTimeout))
{
    await client.WaitForSidecarAsync(tokenSource.Token);
}

// Perform Dapr component operations here i.e. fetching secrets.

Shutdown the sidecar

var client = new DaprClientBuilder().Build();
await client.ShutdownSidecarAsync();