# Execution Plane HTTP
`execution_plane_http` owns the lower unary HTTP lane and lane-adapter
boundary for request/response execution. Version 0.2.0 adds a cancelable unary
session lifecycle backed by Erlang/OTP `:httpc` asynchronous request IDs and
`:httpc.cancel_request/1`.
## Installation
```elixir
def deps do
[
{:execution_plane_http, "~> 0.2.0"}
]
end
```
All commands default to the published `execution_plane ~> 0.3.0` core package.
Workspace development can select a local source through the standard
`MIX_WORKSPACE_OPS_BOOTSTRAP` hook. No registry tooling is required.
## Unary execution
Existing callers can continue using the synchronous helper:
```elixir
{:ok, result} =
ExecutionPlane.HTTP.unary(
%{url: "https://example.com/status", method: "GET"},
lineage: %{idempotency_key: "status-check"}
)
```
Cancelable callers use the same kernel path through a lightweight session:
```elixir
{:ok, session} =
ExecutionPlane.HTTP.start_unary(
%{url: "https://example.com/status", method: "GET"},
lineage: %{idempotency_key: "status-check"}
)
:ok = ExecutionPlane.HTTP.cancel_unary(session, :caller_cancelled)
{:error, result} = ExecutionPlane.HTTP.await_unary(session, 5_000)
```
The process that starts a session owns its terminal result and must call
`await_unary/2`. `cancel_unary/2` may be called from another BEAM process. A
successful cancellation acknowledgment means the request-owning process called
`:httpc.cancel_request/1`; it does **not** prove that a remote service never
received or began processing a request, and it cannot roll back a remote side
effect. Because `:httpc` completion and cancellation are asynchronous, a normal
response that already won the local race may still be the terminal result.
Cancellation reasons are lifecycle-control data only. They are not copied into
the lower execution outcome or raw payload.
## Guides
The HexDocs menu includes the guide index, installation notes, usage notes,
and publishing checklist for this package.