Initial

[stevensJourney]

This PR introduces the initial Alpha implementation of the PowerSync Web SDK.

The Alpha release is very much still Alpha.

High level features include:

• WA SQLite DB adapter running in shared Webworker using IndexDB for persistance.
  • Other storage adapters can be added in future.
• NextJs Demo app using Web SDK.

Future work not included in this PR:

• Updating to NodeJS 20 LTS
• Ability to specify read/write locks in Shared DB Webworker: This will ensure better locking in future when multiple tabs are supported.
• Potentially making a SharedWebworker implementation of the PowerSyncDatabaseClient: to avoid any potential race conditions when syncing with multiple tabs.
• The demo apps are currently located in this SDK repo for convenience, however they could be moved to their own repo if required. This repo could also feature a CLI tool for generating new app from the demo app as a template.
• Demo app does not yet include Attachment helpers
• Better TypeScript typing for WA-SQLite once that is exported better
• Update to faster IndexDB based VFS implementation
• Add PWA support to Demo App

TODOs

• Bump WA-SQLite packages after approval
• Bump Common SDK packages after publish
• Change package access to public

Related PRs powersync-ja/wa-sqlite#1

Some nice screenshots of Demo App follow

[Manrich121]

Not sure if putting this into a package makes sense. I think we should rather look into composable demos, similar to how expo examples templates work:

npx @journeyapps/powersync-create-app --templates "ts-todolist-app" "ts-with-attachments"

[stevensJourney]

Good point. I updated the comment for future investigation

[rkistner]

The IDBBatchAtomicVFS is much faster than this one.

[stevensJourney]

That one seems to cause a corrupted DB error to occur. I will add this to the list of future items to investigate for now.

[rkistner]

I know there were some major db corruption issues related to that, fixed in SQLite 3.44.

[stevensJourney]

Thanks for that! I updated the wa-sqlite build to use SQLite 3.44 and applied the fixes from the PR in the linked issue. This now uses IDBBatchAtomicVFS

[rkistner]

For the demo: Looks good overall, but didn't check the details.
For a next iteration, it would be good to convert it to a PWA (basically just add a service worker and manifest), so that it can work fully offline.

For the database implementation: Looks good, don't see any issues.