I need to implement an http2 server, both in node and in C++. Anyhow, I can't grasp how to make streaming works with static compression:
I want to compress my files with the highest compression possible, and this is done statically at build time
I want to stream my HTML, so the browser receives the <head> asap, and can either prefetch resources or retrieve them from the local cache
But files that are compressed can't be read before receiving all the data, can they?
Should I give up compression, or should I compress HTML stream chunks separately? Is there a better way?
But files that are compressed can't be read before receiving all the data, can they?
This is (generally) incorrect. Deflate based compression (e.g. gzip, brotli) as used for HTML files can be decompressed without receiving all the data.
These work mostly by back-referencing data. For example the above sentence has a repeated reference to the text “compress”:
Deflate based compression (e.g. gzip, brotli) can be decompressed without receiving all the data.
So the second instance could be replaced with a back reference to the first one:
Deflate based compression (e.g. gzip, brotli) can be de(-49,8)ed without receiving all the data.
So you can see that as long as you are reading in order (which HTTP guarantees) and from the beginning, then you don’t need any subsequent data to decompress what you’ve already received - but you do need any previous text.
Similarly JPEGs are often displayed before they are fully received, either by loading it line by line (non-progressive JPEGs), or by having a blurry image which is enhanced as more data is loaded (progressive JPEGs).