Synchronizing HTML5 databases using XQuery

HTML5 has shifted the original model of the web from a thin client
architecture to a thick client architecture.
In such setup, the browser runs a full-fledged application with a
client database, namely IndexedDB, that synchronises with the Cloud.
This new generation of application puts a tremendous amount of
pressure on two aspects of the HTML5 database: complex query
processing of the client data and synchronisation with the Cloud.
We think that XQuery can help.
The goal of this presentation is to showcase how XQuery can be used in
the context of HTML5 applications.
First, XQuery is a powerful query language to process the
semi-structured data that lives in the browser.
Moreover, declarative updates from XQuery can be used to efficiently
synchronise an HTML5 databases with the Cloud.
We will introduce a master-to-master replication protocol between
IndexedDB and MongoDB entirely based on the composition of
pending update lists.
We will demonstrate the protocol in action and detail the various
interaction between HTML5 and XQuery in this context.

Transcript

1. Synchronizing HTML5 Databases using XQuery w@28.io
2. •Application Manifest •URL Decoupling •Databindings •Client Database Web Application APIs
3. MVC MVC
5. “Speed is the second biggest engagement driver on the Internet. Just after perceived speed” Alex MacCaw
6. CAP Theorem Availability Consistency Partion Tolerance Latency Compensation
7. Synchronization?
   ! Query Processing?
8. How to Synchronize Client Data with the Cloud?
9. PULs as Deltas delete insert into
10. PUL Operators •Normalization •Inversion •Composition
11. Normalization normalize( insert { title: "Eat" } into $todo, insert { done: false } into $todo
 ) -> insert { title: "Eat", done: false } into $todo
12. Inversion inverse( current-snapshot(), insert { title: "Eat" } into $todo
 ) -> delete $todo.title
13. Composition compose( insert { todo: "Eat" } into $todos, delete $todos[$$.todo eq "Eat"]
 ) -> ()
14. Composition compose( insert { title: "Eat" } into $todos, replace value of $todos[$$.title eq "Eat"].title with "Buy Food"
 ) -> insert { title: "Buy Food" } into $todos
15. Using PULs for Versionning Server v0 v1 v2 Local PULs Δ1 Δ2
16. Synchronization Server v0 v1 v2 Δ1 Δ2 Δc v0 Client checkout(v0) (Δc,  v2) v2
17. Synchronization Server v2 v3 v2 Client update(v2  ,  Δc) ACK Δc v3
18. Synchronization Server v2 v3 v2 Client 1 update(v2  ,  Δc) ACK Δc v3 v2 Client 2 v3 update(v2  ,  Δc,  v3)
19. Synchronization Server v2 v3 v2 Client 1 update(v2  ,  Δc) Δc ? Merge Policies Conflict detection! and reconciliation operators
20. How To Query
    Client Data?
21. •Ubiquitous •Low Level •Asynchronous •No Type Safety •Room for high level languages The Assembly of the Web
22. Zorba.js
23. •Goal: Compile Zorba to JS •Tool: Emscriptem •LLVM bitcode-to-JS compiler •Emits ASM code 
 An optimizable, low-level subset of JavaScript Zorba.js (1/2)
24. •Bidirectional bridge: C++ & JS •zorba.min.js.gz: ~ 1.3 MB •Future Work: Store API to IndexedDB Zorba.js (2/2)
25. •IJSONiq: https://github.com/ ldoblies/ijsoniq •Zorba.js: https://github.com/ wcandillon/zorba.js •XQLint: https://github.com/ wcandillon/xqlint Resources
26. Thank You