HTTP/2 (originally named HTTP/2.0) is a major revision of the HTTP network protocol used in the Internet.
The HTTP Upgrade mechanism is used to establish HTTP/2 starting from plain HTTP. The client starts a HTTP/1.1 connection and sends “Upgrade: h2c” header. If the server supports HTTP/2, it replies with HTTP 101 Switching Protocol status code. The HTTP Upgrade mechanism is used only for cleartext HTTP2 (h2c). In the case of HTTP2 over TLS (h2), the ALPN TLS protocol extension is used instead.
The h2 plugin for PATHspider aims to detect breakage in the Internet due to the use of HTTP/2.
The path given to the example list of web servers is taken from a Debian GNU/Linux installation and may differ on your computer. These are the same examples that can be found in the examples/ directory of the source distribution.
To use the H2 plugin, specify
h2 as the plugin to use on the command-line:
pspdr measure -i eth0 h2 </usr/share/doc/pathspider/examples/webtest.ndjson >results.ndjson
This will run two HTTP GET request connections over TCP for each job input, one without requesting an upgrade and one requesting an upgrade to HTTP/2.
Supported Connection Modes¶
This plugin supports the following connection modes:
- http - Performs a GET request
- https - Performs a GET request using HTTPS
To use an alternative connection mode, add the
--connect argument to the
invocation of PATHspider:
pspdr measure -i eth0 h2 --connect https </usr/share/doc/pathspider/examples/webtest.ndjson >results.ndjson
The following conditions are generated for the H2 plugin:
For each connection that was observed by PATHspider, a connectivity condition will be generated to indicate whether or not connectivity was successful using HTTP/2 against a connection using HTTP/1.1.
Y may have the following values:
- works - Both connections succeeded
- broken - Baseline connection succeeded where experimental connection failed
- offline - Both connections failed
- transient - Baseline connection failed where experimental connection succeeded (this can be used to give an indication of transient failure rates included in the “broken” set)
For each connection that was observed by PATHspider, a connectivity condition will be generated to indicate whether or not an upgrade request to HTTP/2 was successful. X can have two values, “success” or “failed”.
- The H2 plugin uses cURL options to set the HTTP version to be used for the request and uses the version negotiation techniques built-in to cURL.