Interface IDiscoveryClient

Namespace

Steeltoe.Common.Discovery

Assembly

Steeltoe.Common.dll

Provides access to remote service instances using a discovery server.

public interface IDiscoveryClient

Properties

Description

Gets a human-readable description of this discovery client.

string Description { get; }

Property Value

string

Methods

GetInstancesAsync(string, CancellationToken)

Gets all service instances associated with the specified service ID from the discovery server.

Task<IList<IServiceInstance>> GetInstancesAsync(string serviceId, CancellationToken cancellationToken)

Parameters

serviceId string

The ID of the service to lookup.

cancellationToken CancellationToken

The token to monitor for cancellation requests.

Returns

Task<IList<IServiceInstance>>

The list of remote service instances.

GetLocalServiceInstance()

Gets information used to register the local service instance (this app) to the discovery server.

IServiceInstance? GetLocalServiceInstance()

Returns

IServiceInstance

The service instance that represents this app, or null when unavailable.

GetServiceIdsAsync(CancellationToken)

Gets all registered service IDs from the discovery server.

Task<ISet<string>> GetServiceIdsAsync(CancellationToken cancellationToken)

Parameters

cancellationToken CancellationToken

The token to monitor for cancellation requests.

Returns

Task<ISet<string>>

The list of service IDs.

ShutdownAsync(CancellationToken)

Deregisters the local service (this app) from the discovery server.

Task ShutdownAsync(CancellationToken cancellationToken)

Parameters

cancellationToken CancellationToken

The token to monitor for cancellation requests.

Returns

Task

Remarks

This method exists for two reasons, instead of just reusing IAsyncDisposable. The first reason is that this method enables cancellation. The second reason is more complicated. Deregistration typically requires to send an HTTP request to the discovery server. When using IHttpClientFactory, it requires the IoC container to obtain an HttpClient. But that fails when the container is being disposed. Deregistration must be performed earlier. That's why implementations should register DiscoveryClientHostedService in the IoC container, which is a hosted service that performs deregistration (by calling this method) when the app is terminating. At that time, the IoC container is still accessible.