# Read compressed responses

**For:** Rust developers who want smaller downloads from servers that compress.

You turn on gzip support so the server can send a compressed body and you still read plain text. Then you turn decoding off to see the compressed bytes that came over the network.

Before you start: you need Rust with Cargo. fibre_http comes from crates.io as `fibre_http = "0"`.

## Set up the project

Start a new binary crate.

```sh
cargo new compressed
cd compressed
```

Put this in the `[dependencies]` section of `Cargo.toml`:

```toml title="Cargo.toml"
[dependencies]
fibre_http = { version = "0", features = ["gzip", "json"] }
serde_json = "1"
```

`gzip` is what lets the client decode gzip bodies. A `zstd` feature does the same for zstd.

## The program

httpbin.org's `/gzip` always answers with a gzip body. Replace `src/main.rs` with this:

```rust title="src/main.rs"
use fibre_http::SyncClient;
use serde_json::Value;

fn main() -> Result<(), fibre_http::Error> {
    let client = SyncClient::new();
    let response = client.get("https://httpbin.org/gzip").send()?;
    println!("content encoding: {:?}", response.headers().get("content-encoding"));
    let body: Value = response.json()?;
    println!("gzipped: {}", body["gzipped"]);

    let raw = SyncClient::builder().decompress(false).build_sync()?;
    let bytes = raw.get("https://httpbin.org/gzip").send()?.bytes()?;
    println!("without decompression the body starts with {:02x?}", &bytes[..2]);
    Ok(())
}
```

Run it:

```shell-session
$ cargo run
content encoding: None
gzipped: true
without decompression the body starts with [1f, 8b]
```

## What each part does

With the `gzip` feature on, every request tells the server it accepts gzip. When a gzip body comes back, the client decodes it as it reads, so `json()` sees plain JSON. The `Content-Encoding` header is gone from the response because the body you read is no longer compressed.

`decompress(false)` turns decoding off for that client. The body comes back exactly as the server sent it. `1f 8b` are the two bytes every gzip stream starts with.

A request that sets its own `Accept-Encoding` header also gets the body as the server sent it, whatever the client's setting.

## Where to go next

The usage guide covers the decoding options: [https://github.com/excsn/fibre/blob/main/http/README.USAGE.md](https://github.com/excsn/fibre/blob/main/http/README.USAGE.md)