http2-cache.js



Exposes http caching to the browser by adding functionality to XMLHttpRequest, and then running XMLHttpRequest over http2 over WebSockets

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#### This library is pre 1.0.0, much of the functionality is not yet fully implemented.

This library provides a user-space based HTTP/2 client implementation and cache that slots
in under traditional network Browser APIs such as XHR (eventually Fetch). This project is
intended to be useful for 1. providing HTTP/2 emulation when not natively available and
2. allowing backends to pre-populate a browser-side cache via HTTP/2 push.

This project is designed to be 100% spec compliant. It should be removable without loss
of functionality when there is universal support for HTTP/2 with a consistent H2-cache
implementation.

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HTTP/2 (RFC-7540) runs in userspace by running it on top of WebSocket. An HTTP (RFC-7234) in
memory cache implementation stores cacheable responses. The XHR API can be configured to route
a subset of requests via this transport stack.

A consistent implementation for caching HTTP/2 push requests has not yet emerged. See
discussion
for current the state of the world. This HTTP/2 implementation will not use the cache for
any request (Including HTTP/2 pushed) that contains the
request cache-directive "no-cache".
HTTP/2 pushed requests that do not include this directive may have their HTTP/2 stream aborted
by the client if the cache already contains a cached response for that request. I.E. use the
request cache-directive "no-cache" when doing cache-busting. This should work in all cases where
you want to do a cache replacement.

HTTP/2 push requests require an established stream to send the push request. The API provides a
means to open a long-lived upstream request to an arbitrary location that may be used to send
push requests. Alternatively, streams may be left open for sending future pushed responses via
"long-pushing", that is sending the push promise for a future response, prior to completing the
response to an existing request. I.e. always maintain one response in flight, by sending the push
promise for it prior to completing a response.

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The API attaches to the XMLHttpRequest object.

``javascript
XMLHttpRequest.proxy([urls of configurations])
`

The proxy([urls of configurations]) triggers fetching of JSON configurations on the backend
server. The configurations should be of the following form:

`
{
// Logger debugLevel true='info' or (info|debug|trace)
"clientLogLevel": false,
// Transport endpoint
"transport": "wss://where-the-underlying-ws-transport-connects:443/",
// Transport push path
"push": "optional-path-that-is-opened-for-pushes",
// Transport reconnect settings
"reconnect": true,
"reconnectInterval": 100,
"maximumReconnectInterval": 4000,
// AccelerationStrategy default to "always" can be "connected"
// - Value "always" means always/don't make requests if they are proxied but no ws connection is open.
// - Value "connected" means make requests when connected via websocket.
"accelerationStrategy": "always",
"proxy": [
"http://origin-to-send-via-http2:80/path/",
"http://origin-to-send-via-http2:80/path2/",
"http://other-origin-to-send-via-http2:80"
]
}
`

In full

`html


`

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The integration tests require Java JDK 8 be installed.

`bash
npm i
npm run build
`

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`bash
npm run test:browser
``