LAS Stream Viewer

Stream very large (10 GB+) LAS well-log files line by line in the browser. A Java 21 / Quarkus backend indexes and streams the file with a constant, tiny memory footprint; a React + Vite UI renders millions of lines via virtualization and plays them back as a live SSE stream.

Built for the Pason-style LAS 2.0 logs in Desktop\LAS files (up to ~12.5 GB, 426 curves, ~2.5 M rows). Nothing about the design assumes the file fits in memory.

Why it scales

Concern	Approach
Open a 12.5 GB file	Open-in-place (no copy) — or resumable chunked upload for remote files
Random access into the file	One-pass sparse byte-offset index (a checkpoint every 256 lines ≈ 80 KB for 2.5 M lines)
Indexing memory	Single streaming pass, 1 MiB buffer — independent of file size
Streaming memory	One `BufferedReader` advanced sequentially; lines pushed over SSE with backpressure
Browser memory	Virtualized list (only visible rows in the DOM) + a capped (20 K-line) LRU cache
Reading a line range	Seek to nearest checkpoint, skip ≤ 255 lines — effectively O(1)

Layout

las-stream-viewer/
├─ pom.xml                      Quarkus 3.34.3, Java 21
├─ run.ps1                      dev: Vite (:5173) + Quarkus (:8090)
├─ build.ps1                    prod: bundle UI into the jar, serve on :8090
├─ src/main/java/com/oiusa/las/
│  ├─ model/                    LasFile, Curve, HeaderSection
│  ├─ index/                    LineIndex (sparse offsets), LineReader (random access)
│  ├─ service/                  FileStore, IndexService (one-pass scan), LasHeaderParser, UploadService
│  └─ web/                      File / Lines / Stream(SSE) / Search(SSE) / Upload resources
└─ frontend/                    React + Vite + TS, @tanstack/react-virtual

Run (dev)

cd C:\Users\Dell\Desktop\las-stream-viewer
.\run.ps1

This installs UI deps on first run, starts Vite in a new window, and runs the Quarkus dev server. Open http://localhost:5173.

To run the pieces by hand:

# backend
$env:JAVA_HOME="C:\Program Files\Java\jdk-21.0.11"
$mvn = "C:\Users\Dell\.m2\wrapper\dists\apache-maven-3.9.9-bin\4nf9hui3q3djbarqar9g711ggc\apache-maven-3.9.9\bin\mvn.cmd"
& $mvn quarkus:dev
# frontend (separate window)
cd frontend; npm install; npm run dev

Run (production, single port)

.\build.ps1
$env:JAVA_HOME="C:\Program Files\Java\jdk-21.0.11"
java -jar target\quarkus-app\quarkus-run.jar
# open http://localhost:8090

Using it

Open on disk — browse the server filesystem (constrained to las.allowed-roots, default your home dir) and click a .las file. It opens in place; indexing starts immediately and the header appears as soon as it's parsed.
Upload — drag a file in; it's streamed to the server in 16 MiB chunks.
Watch the LAS header (version/well/curve metadata) populate in the sidebar.
In the viewer: ▶ Stream plays lines server-side over SSE (speed slider = lines/sec), scroll freely through all lines (ranges fetched on demand), jump to Top / Data / End or any line, and Search the whole file (streamed matches, click to jump).

Configuration (`src/main/resources/application.properties`)

Key	Default	Notes
`quarkus.http.port`	`8090`	API (and prod UI) port
`las.data-dir`	`${user.home}/.las-stream-viewer`	where uploads live
`las.allowed-roots`	`${user.home}`	local files may only be opened from under these roots
`las.index-stride`	`256`	lines per index checkpoint (smaller = faster seeks, larger index)
`las.upload-chunk-size`	`16777216`	upload chunk size hint (16 MiB)

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