There are two ways to transmit compressed data via HTTP: Content-Encoding and Transfer-Encoding.
| Content-Encoding | Transfer-Encoding | |
|---|---|---|
| Request header | Accept-Encoding: {algorithms} | TE: {algorithms} |
| Response header | Content-Encoding: {algorithms} | Transfer-Encoding: {algorithms} |
| Influencer | Client and Server | Every node1 |
| Supported / Used | Widely | Rarely |
| Pre-computed | Likely | No |
| ‘Content-Length’ / ‘Ranges’ relates to | … the compressed file | … the uncompressed file |
1 Every node in between can add / remove compression.
Client Proxy1 Proxy2 Server | | | | |----------->| | | |HTTP GET | | | | |-------------------------->| | | |HTTP GET | | | |TE: gzip |----------->| | | |HTTP GET | | | | | | | |<-----------| | | | HTTP 200| | |<--------------------------| | | | HTTP 200| | |<-----------| Transfer-Encoding: gzip| | | HTTP 200| | | | | | |