Pause And Resume

It is possible to pause and resume a flowtide stream, this is useful when there might be maintainance work on a source system, or as a panic button to stop the execution.

A pause does not stop the stream, but stops the traversal of all events inside of the stream. This means that resuming a paused stream is quick and does not need to download any state from persistent storage.

Pause and stop using IConfiguration

One of the easier ways to add pause and resume is to utilize IConfiguration in .NET. Flowtide uses an IOptionsMonitor<FlowtidePauseOptions> to check for changes on the configuration and pauses and resumes the stream based on the value.

The class looks as follows:

public class FlowtidePauseOptions
{
    public bool IsPaused { get; set; }
}

So to utilize this when using FlowtideDotNet.AspNetCore or FlowtideDotNet.DependencyInjection you add the following:

var builder = WebApplication.CreateBuilder(args);

...

// Map flowtide pause options to enable pausing and resuming from configuration
builder.Services.AddOptions<FlowtidePauseOptions>()
    .Bind(builder.Configuration.GetSection("your_section"));

...

// Add the stream as normal
builder.Services.AddFlowtideStream("stream_name")
...

This is best fitted with an IConfiguration provider that supports loading changes dynamically such as Hashicorp Vault or Azure Key Vault. Pausing and resuming using IConfigurationprovider is dependent on the update frequency of the provider, so to utilize this fully this interval should be kept quite low.

Pause and stop using API endpoint

When using FlowtideDotNet.AspNetCore you can also map API endpoints to allow for pause and resume.

Example:

var builder = WebApplication.CreateBuilder(args);

...

// Add the stream as normal
builder.Services.AddFlowtideStream("stream_name")

...

var app = builder.Build();

...

// Map pause and resume endpoints
app.UseFlowtidePauseResumeEndpoints("base_path");

Two endpoints are registered under the base path, /pause and /resume.