Web Development with EPL¶

Build web apps with EPL's native Create WebApp runtime. This is the authoritative served web path used by epl serve, deploy generation, and the maintained starter templates.

Quick Start¶

Create WebApp called app

Route "/" shows
    Page "Hello EPL"
        Heading "Hello from EPL"
        Text "This page is served by the native EPL web runtime."
        Link "Health API" to "/api/health"
    End
End

Route "/api/health" responds with
    Send json Map with status = "ok" and service = "demo"
End

epl serve app.epl
epl serve app.epl --port 3000
epl serve app.epl --dev

Starter Templates¶

epl new mysite --template web
epl new myapi --template api
epl new myauth --template auth
epl new mybot --template chatbot
epl new myui --template frontend
epl new myapp --template fullstack

Native Route Syntax¶

Page route¶

Route "/" shows
    Page "Welcome"
        Heading "Welcome"
        Text "Server-rendered EPL page."
        Link "Users API" to "/api/users"
    End
End

JSON route¶

Route "/api/users" responds with
    users = ["Alice", "Bob"]
    Send json Map with users = users and count = length(users)
End

Request Context Variables¶

Inside native WebApp routes, EPL now exposes request context variables directly:

request_data: POST/PUT/DELETE body as a map
request_params: merged query parameters and path parameters
request_headers: request headers as a map
request_method: HTTP verb
request_path: normalized path
request: combined request object map
session_id: current session identifier when present

Example:

Route "/users/:name" responds with
    name = request_params.name
    role = request_data.get("role")
    Send json Map with name = name and role = role and path = request_path
End

Dynamic Route State¶

You can define variables before Send json and reuse them in page text with $variable templates.

Route "/hello/:name" shows
    title = "Welcome, " + request_params.name

    Page "$title"
        Heading "$title"
        Text "Served with method $request_method"
    End
End

Database Integration¶

Use the supported epl-db facade for application data:

Import "epl-db"

db = open(":memory:")
create_table(db, "notes", Map with id = "INTEGER PRIMARY KEY AUTOINCREMENT" and title = "TEXT NOT NULL")

Route "/api/notes" responds with
    Send json Map with notes = query(db, "SELECT id, title FROM notes ORDER BY id")
End

Authentication Helpers¶

EPL exposes auth helpers directly in the runtime:

hash = auth_hash_password("secret")
ok = auth_verify_password("secret", hash)
token = auth_generate_token(32)

The auth starter template combines these helpers with epl-db and request context bindings for login/register APIs.

Chatbot and AI Apps¶

For chatbot-style apps, use the native WebApp DSL for HTTP routes and the Python bridge for model access:

Import "epl.ai" As ai

Route "/api/chat" responds with
    messages = [Map with role = "user" and content = request_data.get("message")]
    Send json Map with reply = ai.chat(messages)
End

If no local/cloud model backend is configured, wrap the call in Try / Catch and return a fallback response. The chatbot starter template does this for you.

Supported Facade Package¶

If you prefer helper wrappers around the lower-level request/response builtins, install:

epl install epl-web

epl-web is a supported helper facade. The native Create WebApp DSL remains the authoritative served runtime.

Deployment¶

epl deploy docker
epl deploy nginx
epl deploy systemd
epl deploy all

Generated deployment artifacts are validated in CI through Docker Compose, WSGI, and ASGI reference app smoke tests.