This project reads events from a subscription in RabbitMq and pushes them to http endpoints located at Partners
ApiPushService sets up an AutoSubscriber that in its turn uses an AutoSubscriberMessageDispatcher. This is EasyNetQ standard. The Dispatcher is responsible for handling messages. It does that by creating a Consumer.
The AutoSubscriberMessageDispatcher could be skipped, EasyNetQ will then use reflection to create a Consumer by looking at the interface IConsume. The problem with that approach is that it requires a parameterless constructor, we would need to either new up dependencies manually or use a service locator. By using the AutoSubscriberMessageDispatcher instead it becomes easier to inject and mock out dependencies when testing for example.
The Consumer fetches the subscription details from a SubscriptionStorage using the PartnerId from the consumed message from rabbit. If the subscription exists the Consumer uses a PushSender to call an endpoint defined in the subscription for that specific Partner.
A retry policy is used, if we get an http error a configurable amount of retries are done with a exponential back-off strategy with Use the app settings RetryAttempts and RetryDelayInSeconds configurable timing.
Topshelf is used, the application can be run from the command line or installed as a windows servcie. See [http://topshelf.readthedocs.org/en/latest/overview/commandline.html] for installation
There are a few things next up in this project:
- Get the correct messages from rabbit
- A real subscription storage, The clients should be able to subscribe via the public Api
- Security, consider different security aspects, we could use a token in the header and hae shared keys for encrypting messages if needed
- It would be extremly useful to have an option to drop the messages on Amazon SQS instead of calling http endpoints
- The clients could be hammered to death, we could batch messages and send every x minute
- the code could be async instead, some research around how EasyNetQ handle async is probably needed, mainly thinking of batching etc,