---
title: Rust SDK 0.2.0-alpha4
summary: null
url: >-
  https://www.fastly.com/documentation/reference/changes/2020/04/rust-sdk-0.2.0-alpha4
---

## Added

- Added APIs to override caching behavior of backend responses. This replaces the previous `ttl: i32` argument to `send()` and `send_async()`, and adds the ability to override `stale-while-revalidate`. See the `request::CacheOverride` type, as well as the new methods on `RequestExt` and the entirely new `RequestBuilderExt`.

- Added hostcall error code definitions to `XqdStatus`, and updated hostcall implementations to return these error codes.

- Added the `fastly::log` module, which contains a basic interface for writing to Fastly log endpoints.