Robust HTTP processing capabilities (DP3)

[dhmlau]

Based on discussion with @raymondfeng @kjdelisle:
We need robust HTTP processing capabilities to deal with HTTP layer policies

• e.g. CORS, compression/decompression, content negotiation.

@raymondfeng 's initial investigation:

• we don't want to take the burden to implement the HTTP stack.
• base functionality from node core is not good enough
• Possibility is:
  • to use Express base without routing plus the common middleware
  • or we can use Koa

DP3 scope

• Must have: rework internals to use Express request/response types
• Leverage CORS middleware instead of the current workaround (minimal refactoring)
• HttpEndpointFactory - a new module to deal with HTTP(S) setup, a dependency of @loopback/rest
• Stretch goal: serving OpenAPI spec document should be implemented in a controller method

Out of scope

• Local API Explorer (Swagger UI) should be implemented using Express middleware
• Expose Express to app developers, allow them to add custom middleware

Additional Information

• Spike: [Spike] Use Express / Koa for HTTP processing #1071
  • See spike outcome and discussion starting from this: [Spike] Use Express / Koa for HTTP processing #1071 (comment)

Relevant: #180

[bajtos]

Yesterday, we reviewed DP3 scope for this epic with @raymondfeng and @dhmlau and decided on the following feature set:

• Must have: rework internals to use Express request/response types
• Leverage CORS middleware instead of the current workaround (minimal refactoring)
• HttpEndpointFactory - a new module to deal with HTTP(S) setup, a dependency of @loopback/rest
• Stretch goal: serving OpenAPI spec document should be implemented in a controller method

[dhmlau]

Thanks @bajtos. Trying to map your list above to the tasks we have in this EPIC:

• Must have: rework internals to use Express request/response types (Change (req, res) pair to a single http context object #1292, Configurable response types/formats #436)
• Leverage CORS middleware instead of the current workaround (minimal refactoring) (??)
• HttpEndpointFactory - a new module to deal with HTTP(S) setup, a dependency of (HTTP endpoint factory #1331, Support HTTPS out of the box #430)
• Stretch goal: serving OpenAPI spec document should be implemented in a controller method (Serve OpenAPI spec from a controller method #1332)

[bajtos]

Must have: rework internals to use Express request/response types

This is mostly #1292 and #1326.

#436 IS NOT related.

Leverage CORS middleware instead of the current workaround (minimal refactoring)

I'd like to send a pull request today, I am not sure if we need a story.

HttpEndpointFactory - a new module to deal with HTTP(S) setup

This is tracked by #1331 with a follow-up in #430.

Stretch goal: serving OpenAPI spec document should be implemented in a controller method (#1332)

This is correct.

I added one more story to the epic - Blog post: Leveraging Express for a more robust HTTP processing #1337.

[bajtos]

Leverage CORS middleware instead of the current workaround (minimal refactoring)

See #1338