ExpressLite Extension v1

[rasi_tech]

ExpressLite Extension V1

ExpressLite is a non-visible extension that brings a lightweight HTTP server to Android, with an Express.js-like workflow: register routes (GET/POST/PUT/DELETE/ALL), capture path params (/hello/:name), read query, headers, and body (text/JSON), enable CORS, and send responses from Blocks.

Why for Kodular/AI2?

• No external libraries (pure ServerSocket) → compiles on Kodular/AI2 without JARs.
• Java 7 compatible (no lambdas/Streams).
• Great for LAN/edge debugging, local webhooks, device-to-device APIs.

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Features

• Express-style route patterns: /path/:param and wildcard *
• Events: OnRouteRequest and OnNotFound
• Respond with Text / JSON / Binary (Base64)
• CORS with preflight OPTIONS
• Properties: Port, LocalURL(), RequestTimeoutMs
• Zero external dependencies

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Installation

1. Import ExpressLite.aix into your Kodular/AI2 project.
2. Drag the ExpressLite non-visible component to the screen.
3. Ensure the app has INTERNET permission (enabled by default).

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Quick Start

Blocks outline:

1. Set Port = 8080

2. Call StartServer() → read LocalURL() (e.g. http://192.168.1.5:8080)

3. Register routes:

   • AddRoute("hello", "GET", "/hello/:name")
   • AddRoute("echo", "POST", "/echo")

4. Handle OnRouteRequest → reply using SendTextResponse / SendJsonResponse.

Test from PC (replace IP with LocalURL()):

# GET + path param & query
curl "http://192.168.1.5:8080/hello/Rasi?lang=id"

# POST JSON
curl -X POST "http://192.168.1.5:8080/echo" \
  -H "Content-Type: application/json" \
  -d '{"msg":"Hello world"}'

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Simplest Example: return "hello" at "/"

Blocks (pseudo):

when Screen.Initialize
  set ExpressLite.Port to 8080
  call ExpressLite.StartServer
  call ExpressLite.AddRoute("root", "ALL", "/")

when ExpressLite.OnRouteRequest(routeName, requestId, method, path, paramsJson, queryJson, headersJson, bodyText)
  if routeName = "root"
    call ExpressLite.SendTextResponse(requestId, 200, "text/plain; charset=utf-8", "hello")

Test:

curl "http://<PHONE-IP>:8080/"
# -> hello

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API Reference

Properties

Name	Type	Description
Port	Number	Server port. Set before StartServer().
LogEnabled	Boolean	Enable/disable internal logs (optional).
RequestTimeoutMs	Number	Time limit to wait for a Block response (default 30000 ms).
LocalURL()	Text	Current base URL (e.g., http://192.168.1.5:8080).

Functions

Function	Parameters	Description
StartServer()	—	Starts the server. Returns base URL (Text).
StopServer()	—	Stops the server if running.
SetCORS(enabled, allowOrigin, allowMethods, allowHeaders)	Boolean, Text, Text, Text	Enable/configure CORS. Default: enabled with * and OPTIONS preflight.
AddRoute(routeName, method, pathPattern)	Text, Text, Text	Add a route. method: GET/POST/PUT/DELETE/ALL. pathPattern supports :param & *. Returns effective routeName.
RemoveRoute(routeName)	Text	Remove a route by name.
ClearRoutes()	—	Remove all routes.
SendTextResponse(requestId, status, contentType, body)	Text, Number, Text, Text	Send a text response.
SendJsonResponse(requestId, status, jsonText)	Text, Number, Text	Send a JSON response (Content-Type: application/json; charset=utf-8).
SendBinaryResponse(requestId, status, mimeType, base64Data)	Text, Number, Text, Text	Send a binary response from Base64.

Events

Event	Parameters	Description
OnRouteRequest	routeName, requestId, method, path, paramsJson, queryJson, headersJson, bodyText	Fired when a route matches. Use requestId with a Send...Response function to reply.
OnNotFound	requestId, method, path	Fired when no route matches (404). You may reply manually: SendTextResponse(requestId, 404, "text/plain", "Not Found").

Notes about event params

• paramsJson → extracted from :param in pathPattern (e.g., /user/:id → {"id":"42"}).
• queryJson → query map with array values per key (supports ?x=1&x=2).
• headersJson → headers map (single value per key).
• bodyText → request body as string (client must send Content-Length; chunked is not supported).

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Route Pattern Examples

Pattern	Matches	paramsJson
/hello/:name	/hello/Ana	{"name":"Ana"}
/file/*	/file/a/b/c.txt	{} (use full path if needed)
/u/:id/profile	/u/42/profile	{"id":"42"}

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Security & CORS

Enable CORS if you call the server from a web page:

SetCORS(true, "*", "GET,POST,PUT,DELETE,OPTIONS", "Content-Type, Authorization")

For private LAN tools, * is convenient. For stricter setups, whitelist origins and headers.

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Troubleshooting

• Cannot access from PC
  Ensure phone and PC are on the same Wi-Fi/LAN. Check firewall/router/VPN.

• 504 Timeout
  OnRouteRequest fired, but no Send...Response was called within RequestTimeoutMs. Ensure you respond.

• Empty body
  Server reads body via Content-Length (no chunked support). Make sure clients send the header and proper length.

• Internet/WAN exposure
  Not recommended. This is a lightweight LAN server. If you must, put a reverse proxy/TLS in front and implement authentication.

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Limitations

• No built-in TLS (HTTPS).
• No keep-alive / chunked transfer (one request per connection → simple and stable).
• Large uploads/multipart not optimized yet.
• Not intended for high traffic or public Internet exposure.

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Download

com.rasitech.expresslite.aix (31.6 KB)

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Changelog

• v2 — Self-contained server (ServerSocket), CORS preflight, JSON helpers, this EN doc.
• v1 — Initial NanoHTTPD-based prototype (replaced to remove external dependencies).

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License

Sample code & docs: Apache-2.0. Feel free to use and modify with reasonable attribution.

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FAQ

Q: Can I use it as a local webhook endpoint?
A: Yes. Run the server on the phone, keep clients on the same LAN, or use a tunnel on a separate machine (mind the security).

Q: Can it serve static files?
A: Current focus is replying from Blocks (Text/JSON/Binary). Static files can be added in a future version if there’s interest.

Q: WebSocket support?
A: Not yet. The scope is a simple HTTP request/response server. If the community needs it, it can be explored.