# 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, "~> 0.2.0"}]
end
```
2. Ensure `pollin` is started before your application:
```elixir
def application do
[applications: [:pollin]]
end
```
## Usage
### Endpoint Resources
```elixir
# Add alias to your module (optional)
alias Pollin.Backend.Memory.EndpointWorker
alias Pollin.Resource.Endpoint
```
- Create an endpoint
```elixir
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
```elixir
id
|> EndpointWorker.find
|> Map.put(:secret, "new secret")
|> EndpointWorker.update
```
- Delete an endpoint
```elixir
EndpointWorker.delete(id)
```
- List all endpoints
```elixir
EndpointWorker.index
```
- Find an endpoint
```elixir
endpoint = EndpointWorker.find(id)
```
### Callbacks Resources(WebHooks / Event Sources)
- Push a callback resource to an endpoint
```elixir
CallbackWorker.push(id, %Pollin.Resource.Callback{})
```
- Pop a callback from endpoint
```elixir
callback = CallbackWorker.pop(id)
```
- Pop a callback by an exact key from endpoint
```elixir
callback = CallbackWorker.pop(id, key)
```
- Pop list of callbacks from an endpoint queue by given phase, offset and limit
```elixir
callbacks = CallbackWorker.pop(id, opts)
```
- Pop list of callbacks from endpoint queue by given options offset and limit
```elixir
callbacks = CallbackWorker.pop(id, opts)
```
- Pop a callback from endpoint
```elixir
callback = CallbackWorker.fetch(id)
```
- Pop a callback by an exact key from endpoint
```elixir
callback = CallbackWorker.fetch(id, key)
```
- Fetch list of callbacks from an endpoint queue by given phase, offset and limit
```elixir
callbacks = CallbackWorker.fetch(id, opts)
```
- Fetch list of callbacks from endpoint queue by given offset and limit
```elixir
callbacks = CallbackWorker.fetch(id, opts)
```
- Fetch reverse list of callbacks from an endpoint queue by given phase, offset and limit
```elixir
callbacks = CallbackWorker.fetch(id, opts)
```
- Fetch reverse list of callbacks from endpoint queue by given offset and limit
```elixir
callbacks = CallbackWorker.fetch(id, opts)
```
- Count all callbacks of an endpoint
```elixir
count = CallbackWorker.count(id)
```
- Count all callbacks of an endpoint with filter options
```elixir
count = CallbackWorker.count(id, %{phase: "unprocessed"})
```
- Dump all callbacks of an endpoint
```elixir
callbacks = CallbackWorker.count(id)
```
- Reset all callbacks of an endpoint
```elixir
CallbackWorker.reset(id)
```
- Remove a callback
```elixir
CallbackWorker.delete(id, key)
```
- Update phase of a callback
```elixir
CallbackWorker.update_phase(id, key, phase)
```
### 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
