React Helsinki February 2020

Henri Vesala: Hard Lessons Learned with Apollo Graphql
Tuomas Artman: Real-time sync for web apps

[@Antman261]

This is really interesting. We have a completely different approach to real-time sync between multiple clients, but it doesn't support offline mode (although maybe it could). Our clients dispatch commands via websockets, and our server processes the commands, if it is accepted, it publishes an event. Events are then emitted back to all interested clients, along with the new state. In order to prevent commands being issued based on stale state, every event message includes a sequence id, which the client must include in commands it is sent. If a command is issued based on a stale sequence id, the command is rejected. However, if we rebased the stale commands onto the latest state, we could probably support offline mode. Also, we actually build our state in memory on the server using redux. So we have effectively hoisted react state all the way up onto the server 😁 We do also use observables, but we actually do it using javascript proxies to build indexes, simply to speed up lookups on mutable properties.

[@GotsOJ]

This sounds amazing-is there a way I could read/learn more?

[@fuads]

What you're describing sounds close to what Operational Transformation, although in OT the server does the "rebase" step.

[@Antman261]

@@GotsOJ One day we'll need to write up our approach in our engineering blog, but currently no, we don't have anything written up about it publicly

[@Hirschischnitte]

@@Antman261 is there anything out there yet?

[@codeit9023]

Fantastic talk by Tuomas Artman! I particularly enjoyed a clear understanding of the underlying details & great level of explanation🙂👍🏻

[@RIP212]

Tuomas - amazing talk. Please do open source the thing as I feel like I'm going to write one shitty one myself :DDD Big fan of Linear.

[@kukasmog]

Artman’s presentation was on point!

[@tobias3581]

Amazing. Curious if the classes with decorators that defines the graph api are used to sync mongo as well? If the model changes, how many places must be manually updated?

[@benjaminakar]

Very interesting talk, Artman! 👏🏼

[@mrelec1000]

Really enjoyed Artman's talk!

[@ionionion]

Great talk 👌 Will you open source it ? 🙃

[@ThugLifeModafocah]

About the linear presentation: and how do you guys handle conflicts when two people changes something at the same time and how it handles when they did changes almost at the same time? Think about these 2 questions in these 2 scenarios: when they have internet connection and when they are offline.

[@ThugLifeModafocah]

So, nevermind, the guy at 1:10:10 just asked the same thing as I.😅

[@jimshtepa5423]

has anyone tried to implement what Artman explained in this video? how does the source code look like?

[@seannewell397]

Really wanted to see the .save in context in a component 😬

[@SimonKubicaPM]

Tuomas = 🐐

[@briceleroy]

I'm confused regarding the Reat-time sync for web apps. It looks like using redux and selectors instead of mobX would have avoided all this complexity and postfixed ID tricks.

[@nonefvnfvnjnjnjevjenjvonej3384]

Or one can use just rails action cable and get rid of all those different layers / complexity at one go.