# `Arangox.VelocyClient`
[🔗](https://github.com/ArangoDB-Community/arangox/blob/v0.8.0/lib/arangox/client/velocy.ex#L2)

The [VelocyStream](https://github.com/arangodb/velocystream) client, an
explicit opt-in for ArangoDB 3.11 deployments
(`client: Arangox.VelocyClient`) — the server removed the protocol in
3.12, and `Arangox.MintClient` over HTTP is the default.

Conforms to the `Arangox.Client` error contract: every failure is an
`Arangox.Error` carrying a `:reason` atom, and neither `connect/2` nor
`request/3` raises or exits, whatever the transport does with the options it
is given.

VelocyStream carries headers as a map in *both* directions, so this
client cannot express a repeated header name. Outbound, it builds the map
from the merged list itself: the right-most occurrence of a name wins and
the others are dropped. Inbound, the list on `Arangox.Response` is built
from the server's map: no repeated name can arrive, and the order is the
map's key order, not the order the server wrote them. Casing is preserved
in both directions — unlike the HTTP clients, which lowercase names.

URI query parsing functions proudly stolen from Plataformatec and
licensed under Apache 2.0.

# `maybe_authenticate`

```elixir
@spec maybe_authenticate(Arangox.Connection.t(), [Arangox.Client.request_option()]) ::
  :ok | {:error, Arangox.Error.t()}
```

# `vst_maxsize`

> This function is deprecated. Pass :vst_maxsize to Arangox.start_link/1 instead.

```elixir
@spec vst_maxsize() :: pos_integer()
```

Returns the _VelocyStream_ chunk size from the deprecated application config,
or `30_720`.

Deprecated in 0.8 and removed in the next release, along with the
application-config read it reports on. It returns the *fallback*, not what any particular pool uses:
since 0.8 the chunk size is a per-pool start option, resolved at connect and
held in `Arangox.Connection`, so two pools can disagree and neither has to
agree with this. Pass `:vst_maxsize` to `Arangox.start_link/1` instead.

Emits a deprecation warning on every call.

---

*Consult [api-reference.md](api-reference.md) for complete listing*