Pollin

Simple queue implementation for webhooks and event sources. (Pollin package designed for only callbacks and event sourcing for elixir/erlang applications.)

Motivation

Webhook definition from wikipedia: “Webhooks are “user-defined HTTP callbacks”. They are usually triggered by some event, such as pushing code to a repository or a comment being posted to a blog. When that event occurs, the source site makes an HTTP request to the URI configured for the webhook.”

And a little event sourcing (https://ookami86.github.io/event-sourcing-in-practice/)

• Events might have state and sub events

• Webhooks should respond 200 whenever the request gathered from client. You can even skip authentication/authorization and handle the all the request from the queue.

• Webhook request should processed using a queue engine.

• Queue engine should support; pop, fetch, update, delete, dump and reset operations.

• Allowing dynamic queue creation and other CRUD actions on queue.

• Extendable backends

Installation

If the package can be installed as:

1. Add pollin to your list of dependencies in mix.exs:

```elixir
def deps do
  [{:pollin, "~> 0.1.0"}]
end
```

1. Ensure pollin is started before your application:

```elixir
def application do
  [applications: [:pollin]]
end
```

Usage

Endpoint Resources

# Add alias to your module (optional)
alias Pollin.Backend.Memory.EndpointWorker
alias Pollin.Resource.Endpoint

• Create an endpoint

id = "some_id_for_endpoint"
endpoint = %Endpoint{id: id, secret: "some secret", ttl: 900_000, created_at: :os.system_time}
EndpointWorker.create(endpoint)

• Update an endpoint

id
|> EndpointWorker.find
|> Map.put(:secret, "new secret")
|> EndpointWorker.update

• Delete an endpoint

EndpointWorker.delete(id)

• List all endpoints

EndpointWorker.index

• Find an endpoint

endpoint = EndpointWorker.find(id)

Callbacks Resources(WebHooks / Event Sources)

• Push a callback resource to an endpoint

CallbackWorker.push(id, %Pollin.Resource.Callback{})

• Pop a callback from endpoint

callback = CallbackWorker.pop(id)

• Pop a callback by an exact key from endpoint

callback = CallbackWorker.pop(id, key)

• Pop list of callbacks from an endpoint queue by given status, offset and limit

callbacks = CallbackWorker.pop(id, opts)

• Pop list of callbacks from endpoint queue by given options offset and limit

callbacks = CallbackWorker.pop(id, opts)

• Pop a callback from endpoint

callback = CallbackWorker.fetch(id)

• Pop a callback by an exact key from endpoint

callback = CallbackWorker.fetch(id, key)

• Fetch list of callbacks from an endpoint queue by given status, offset and limit

callbacks = CallbackWorker.fetch(id, opts)

• Fetch list of callbacks from endpoint queue by given offset and limit

callbacks = CallbackWorker.fetch(id, opts)

• Fetch reverse list of callbacks from an endpoint queue by given status, offset and limit

callbacks = CallbackWorker.fetch(id, opts)

• Fetch reverse list of callbacks from endpoint queue by given offset and limit

callbacks = CallbackWorker.fetch(id, opts)

• Count all callbacks of an endpoint

count = CallbackWorker.count(id)

• Count all callbacks of an endpoint with filter options

count = CallbackWorker.count(id, %{status: "unprocessed"})

• Dump all callbacks of an endpoint

callbacks = CallbackWorker.count(id)

• Reset all callbacks of an endpoint

CallbackWorker.reset(id)

• Remove a callback

CallbackWorker.delete(id, key)

• Update status of a callback

CallbackWorker.update_status(id, key, status)

Backends

You can implement your own backend using Pollin.CallbackInterface behaviour.

Contribution

Issues, Bugs, Documentation, Enhancements

1. Fork the project

2. Make your improvements and write your tests.

3. Make a pull request.

Todo

• [ ] Implement Phoenix Framework API endpoints

• [ ] Implement base Plug API endpoints

• [ ] Filters

• [ ] Add more backends like redis, cassandra, memcache, other dbs…

License

MIT