EventSub

Azure Event Grid/AWS Eventbridge style ASP .NET service that stores messages in a database and forwards them to a subscriber URL. It's built on top of the excellent Rebus service bus and currently supports MySQL, SQL Server, and PostgreSQL.

Run docker container

docker run -e "DATABASE=PostgreSql" -e "APIKEY=myapikey" -e "CONNECTIONSTRING=Server=host.docker.internal;Port=5432;Database=test;User Id=postgres;Password=password;maximum pool size=30" -p 80:80 --name eventsub tinybluerobots/eventsub

Run from code

Install from nuget and call UseEventSub in your builder

Host.CreateDefaultBuilder(args)
    .ConfigureWebHostDefaults(webBuilder => webBuilder.UseEventSub(Database.PostgreSql("connectionstring"), "apikey"))
    .Build()
    .Run()

There's an example host in ./src/Web, you will need to set the following environment variables:

• DATABASE : The type of database, either MySql, SqlServer, or PostgreSql
• CONNECTIONSTRING : Database connection string
• APIKEY : Api key provided either by query string value apikey or X-API-KEY header

startLocal.sh shows an example of running the service against a local Docker instance of Postgres.
docker.sh shows how to start an instance of each supported DB.

Create a subscriber

POST to /subscribers

{ "name": "mysubscribername",
  "types": ["mymessagetype"],
  "url":"https://myeventhandler.com",
  "retryIntervals": [10, 20, 40],
  "maxParallelism": 1,
  "numberOfWorkers": 1 }

name : lower case alphanumeric name
types : message types that the subscriber will accept, effectively a list of topics
url : URL of handler
retryIntervals : optional array of seconds between retry attempts before message is dead lettered
maxParallelism : optional value to set parallelism of delivery to a subscriber, useful for throttling
numberOfWorkers : optional value of worker threads
Check out the Rebus guide on workers and parallelism for more information on the last two values.

Send a message

POST to /

{ "type": "mymessagetype",
  "data": {"name":"jon"} }

Based on the type value, data will be sent to appropriate subscribers.

Have a look at test.http to see how to read and delete subscribers.