Experimental Livebook-friendly DSL for sketching sequence diagrams.

Unlike most Choreo Lab DSLs, sequence diagrams are primarily ordered event streams rather than static topology. This DSL still uses participant constructors for nouns, but message, activation, note, and fragment statements compile to ordered Choreo.Sequence events.

Examples

iex> import Choreo.Lab.DSL.Sequence
...> diagram = sequence do
...>   user = actor("User")
...>   api = participant("API")
...>   db = participant("Database")
...>
...>   user ~> api |> call("GET /accounts")
...>   activate api
...>   api ~> db |> call("SELECT accounts")
...>   reply db ~> api, "rows"
...>   deactivate api
...>   reply api ~> user, "200 OK"
...> end
iex> Choreo.Sequence.participants(diagram)
[:user, :api, :db]
iex> Choreo.Sequence.messages(diagram) |> Enum.map(& &1[:label])
["GET /accounts", "SELECT accounts", "rows", "200 OK"]

Message edges can use pipe modifiers, typed constructors, or generic edge:

user ~> api |> call("GET /accounts")
async api ~> worker, "enqueue job"
reply db ~> api, "rows"
edge api ~> db, async: "fire and forget"

Notes and fragments are event statements:

over api, "Validates bearer token"
between api, db, "Tenant scoped query"

loop "retry up to 3 times" do
  api ~> worker |> async("process job")
end

alt "authorized" do
  api ~> db |> call("read tenant")
  otherwise "denied"
  api ~> user |> reply("403")
end