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The context: I'm building a cryptocurrency exchange application. I don't have the business chops to run an actual exchange, so this is just for fun. The application is built in Elixir, using the Commanded framework for CQRS/ES goodness, and Phoenix LiveView because it's the hot new thing that I wanted to learn.
The context: I'm building a cryptocurrency exchange application. I don't have the business chops to run an actual exchange, so this is just for fun. The application is built in Elixir, using the Commanded framework for CQRS/ES goodness, and Phoenix LiveView because it's the hot new thing that I wanted to learn.
My goal is to use LiveView to update a price chart as trades are executed by the system. A LiveView process is a lot like a GenServer, with a bespoke process for each client, executing handle_* functions as the client does things. The first step to real-time chart updates is to trigger one of these handler functions in my LiveView controller when a trade is executed. I'm using Commanded's own EventStore library to dispatch and store my events, so their documentation is the place to start.
I'm using Chart.js, which is a popular graphing JavaScript library. It lives entirely on the client-side, which isn't very agreeable with Phoenix LiveView's server-side focus. Fortunately, LiveView allows you to set up JavaScript hooks, and then push events to them. We can make the client event-sourced, too! That's why I'm using push_event/3 instead of assign/3 in the example above. I'm using LiveView's JavaScript hooks to respond to events that I push from the LiveView process. Read more about LiveView JavaScript interoperability, it's really interesting.
The context: I'm building a cryptocurrency exchange application. I don't have the business chops to run an actual exchange, so this is just for fun. The application is built in Elixir, using the Commanded framework for CQRS/ES goodness, and Phoenix LiveView because it's the hot new thing that I wanted to learn.
Now, if you were using a server-side charting library like ContEx, then you would just append the new events to what you've already got assigned to the socket, and your normal rendering function would rebuild the chart. You're done! But I wanted to make it more complicated.