HTTP/2 in TrueLog Explorer

In TrueLog Explorer, you can check the tabs In Header and Out Header to find out whether a request uses HTTP/2. If a request does use HTTP/2, the header tabs display so-called pseudo-headers such as :method, :scheme, :path, :authority, or :status. Note that TrueLog Explorer displays the decompressed version of the headers, because the compressed headers are not human-readable.

When examining the Statistics tab, you might notice some more differences:

• HTTP/2 uses only one TCP connection to download all content from one host. Because of that, only the first request to a host should contain values for DNS, Connect and SSL Handshake. The following requests to the same host will reuse the existing connection.
• When you investigate the waterfall diagram for an API node with many embedded resources, you might notice that in an HTTP/2 case the embedded resources can start downloading simultaneously without waiting for an idle TCP connection. While individual requests might take slightly longer, in total the page should be downloaded significantly faster with HTTP/2 compared to previous versions.
• For HTTP/1.1 traffic, TrueLog Explorer displays the number of bytes transferred including SSL and connection overhead for each web node in the TrueLog tree. For HTTP/2 however, concurrent requests to one host share the same TCP connection, thus portions of multiple concurrent requests or responses might be contained in a single SSL frame. To be able to compare HTTP/1.x with HTTP/2 traffic, TrueLog Explorer displays similar statistics, even though the HTTP/1.1 metrics do not suit well to the new protocol version. In detail this means that TrueLog Explorer distributes the SSL overhead across the corresponding requests and responses. Traffic that does not correspond to a specific request/stream, such as HTTP/2 settings frames, is added to the statistics of the subsequent request/response pair. Some measures can seem small. This is caused by the HTTP/2 header compression feature. Especially when the previous request or response contained many similar headers, this can reduce the number of sent/received bytes for a typical request consisting of mainly headers significantly.
• Due to the nature of HTTP/2, where one frame can contain portions of multiple streams, TrueLog Explorer cannot associate the compressed frame size with particular request/response pairs. Thus, the size of the uncompressed headers and bodies is displayed in the page drill-down view of the Statistics tab.