Implement middle-tier reference architecture

[ericerway]

Description

As a developer I want a platform agnostic approach to creating and deploying PWA storefronts. Builds upon research spike on middle-tier specification.

• Implement development mode with middle-tier
• Minor refactoring of buildpack and Venia (as appropriate)
• Minor refactoring of Magento 2 inegration points
• Supporting documentation (updates)

Expected result:

Summary of findings Internal and external review Additional user stories or scenarios (as appropriate)

Tasks

• [x] Publish first draft of UPWARD whitepaper
• [ ] Complete draft of UPWARD reference API
• [ ] Write UPWARD server test harness
• [ ] Write JS reference implementation
• [ ] Stretch: Integrate into webpack-dev-server as middleware

[ericerway]

Kamino cloned this issue to magento-research/pwa-studio

[ericerway]

Partially complete, remaining tasks moved to #258 in next sprint.

• [ ] Write UPWARD server test harness
• [ ] Write JS reference implementation
• [ ] Stretch: Integrate into webpack-dev-server as middleware