# Solvent
[](https://github.com/Cantido/solvent/actions/workflows/elixir.yml)
[](https://livebook.dev/run?url=https%3A%2F%2Fgithub.com%2FCantido%2Fsolvent%2Fblob%2Fmain%2Fguides%2Fgetting-started.livemd)
An event bus built for ease-of-use.
## Installation
If [available in Hex](https://hex.pm/docs/publish), the package can be installed
by adding `solvent` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:solvent, "~> 0.3.0"}
]
end
```
Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
be found at <https://hexdocs.pm/solvent>.
## Usage
Solvent is flexible enough to offer several ways of delivering events,
and is exensible enough to add your own.
Out of the box, Solvent allows you to subscribe with anonymous functions, module-function-args tuples, PIDs,
and modules that `use` the `Solvent.Subscriber` module.
```elixir
# anonymous functions
Solvent.subscribe(
fn event_id -> IO.inspect(event_id) end,
source: "https://myapp.example.com",
types: ["com.myevent.published"]
)
# module-function-args tuples
Solvent.subscribe
{IO, :inspect, []},
source: "https://myapp.example.com",
types: ["com.myevent.published"]
)
# PIDs
Solvent.subscribe(
self(),
source: "https://myapp.example.com",
types: ["com.myevent.published"]
)
# Subscriber modules
defmodule MySubscriber do
use Solvent.Subscriber,
source: "https://myapp.example.com",
types: ["com.myevent.published"]
@impl true
def handle_event(_event_id) do
IO.puts("I'm handling an event!")
end
end
```
Set up your subscriptions in your application's `start/2` function.
```elixir
def start(_type, _args) do
Solvent.subscribe(MySubscriber)
children = [
# ...
]
opts = [strategy: :one_for_one, name: MyApp.Supervisor]
Supervisor.start_link(children, opts)
end
```
Finally, publish your event using `Solvent.publish/2`.
```elixir
Solvent.publish("com.myevent.published")
```
Specify additonal event data with the `:data` option.
You can specify any optional field from the CloudEvent spec, in fact.
```elixir
Solvent.publish(
"com.myjsonevent.published",
source: "https://myapp.example.com",
datacontenttype: "application/json",
data: ~s({"foo":"bar"})
)
```
Only event IDs are passed to subscriber functions.
You must fetch the associated event using `Solvent.EventStore.fetch/1`.
This small hiccup in an otherwise buttery-smooth developer experience is done in the name of speed.
Copying large amounts of data between processes can be slow,
so Solvent stores events in an ETS table and lets you fetch them when you're ready.
## License
MIT License
Copyright 2022 Rosa Richter
Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
