# Javax

## Overview

The `javax` package is a top-level organizational namespace that groups Java EE (now Jakarta EE) standard APIs. Within this codebase, `javax` primarily serves as the umbrella for JavaServer Faces (JSF) integration — a server-side component framework for building Java web applications using a component-based programming model.

At the point of this documentation, the `javax` module contains no directly indexed source files, classes, interfaces, or methods. All meaningful definitions live in child sub-packages, most notably under `javax.faces`. The codebase appears to be a stub or scaffolding for the JSF API rather than a fully runnable implementation, with structural setup (packages, servlet registration, deployment descriptors) in place but implementation bodies deferred.

This appears to be a test fixture or initial framework scaffolding, where the intent is to eventually wire up a complete JSF implementation on top of the servlet container infrastructure.

## Sub-module Guide

The `javax` module has no directly indexed child modules at its own level, but it contains the `javax.faces` subtree which does have documented sub-packages:

- **`javax.faces`** — The root of the JSF package tree. This package itself contains no source files; it serves as the organizational umbrella under which JSF-related sub-packages are grouped. In a production JSF implementation (Mojarra, MyFaces), this would contain the core APIs for UI components, lifecycle management, context handling, and view rendering.

- **`javax.faces.webapp`** — The servlet integration layer. This is currently the only child module with indexed classes, specifically `FacesServlet`. This package bridges the servlet container and the JSF framework, acting as the front-controller entry point for all HTTP requests processed by JSF.

These sub-packages work together as a layered architecture: `javax.faces.webapp` sits at the servlet boundary, receiving raw HTTP requests and delegating into the broader JSF infrastructure represented by `javax.faces` and its sibling packages. In a complete implementation, packages like `javax.faces.component`, `javax.faces.lifecycle`, and `javax.faces.context` would coordinate with `webapp` to deliver the full JSF experience.

## Architecture

### Component Interaction

The following diagram shows how the `javax` module's sub-packages relate and interact:

```mermaid
flowchart TD
    S["javax (root stub)"] --> F["javax.faces
JSF API umbrella"]
    F --> W["javax.faces.webapp
FacesServlet entry"]
    W --> XML["web.xml / web-full.xml
Servlet registration"]
    W --> SVC["Servlet Container
Request dispatch"]
    SVC --> L["JSF Lifecycle
6 phases (stub)"]
    XML --> SVC
```

The flow is straightforward: deployment descriptors (`web.xml`, `web-full.xml`) instruct the servlet container to route matching requests to `FacesServlet`. The servlet then delegates into the JSF lifecycle phases, which would be implemented in sibling packages under `javax.faces` in a complete implementation.

### Request Flow (Conceptual)

In a fully implemented JSF application, the request flow through the `javax` module follows the standard six-phase JSF lifecycle:

1. **Restore View** — Reconstruct or create the component tree for the requested page.
2. **Apply Request Values** — Populate component state from HTTP request parameters.
3. **Process Validations** — Run validators on input components.
4. **Update Model Values** — Sync component values to backing beans.
5. **Invoke Application** — Execute application-level actions and event handlers.
6. **Render Response** — Generate the HTML (or other markup) for the client.

Since `FacesServlet` is currently a stub, none of this processing occurs — the request flow is structural only, defined by the presence of the class and its registration but not yet functional.

### Design Decisions

The architecture relies on the front-controller servlet pattern, a deliberate JSF design choice that centralizes request handling in a single `FacesServlet`. This enables:

- **Consistent lifecycle execution** — Every JSF request passes through the same phases in order, guaranteeing predictable behavior.
- **Shared state management** — The `FacesContext` is created once per request and passed to all phases, avoiding synchronization problems.
- **Separation of concerns** — View rendering is decoupled from request handling through the lifecycle's render phase, which delegates to component-specific renderers.

This appears to be a stub placeholder within a test fixture, since `FacesServlet`'s class body is empty. The module is functional in structure (correct package, correct class name, wired into deployment descriptors) but deferred in implementation.

## Dependencies and Integration

### Deployment Configuration

| Consumer | Role |
|----------|------|
| `web.xml` | Standard servlet registration and URL mapping |
| `web-full.xml` | Full Java EE profile variant of configuration |

Both deployment descriptors declare and map `FacesServlet`. The servlet container reads these at application startup to register the servlet and route matching requests to it. The presence of both files suggests this project targets both standard and full Java EE profiles, which requires consistent servlet mappings across both.

### Expected Framework Dependencies

In a complete JSF implementation, `javax.faces.webapp` would depend on:

- **`javax.servlet`** — for HTTP request/response handling.
- **`javax.faces.context`** — for creating and managing the `FacesContext`.
- **`javax.faces.lifecycle`** — for invoking the six lifecycle phases.
- **`javax.faces.component`** — for the component tree that represents the view.

The current stub has no declared dependencies beyond what the servlet container provides, since the class body is empty.

## Notes for Developers

1. **This is a stub.** `FacesServlet` is declared but contains no implementation. Production code relying on JSF request processing will need the implementation filled in.

2. **URL mapping governs behavior.** The requests that enter the JSF lifecycle are determined by the URL pattern configured in `web.xml` and `web-full.xml`. Common patterns include `*.jsf`, `*.faces`, or `/faces/*`.

3. **Only GET and POST are handled.** A real `FacesServlet` typically processes only GET and POST requests. Other HTTP methods are passed through unchanged and should be handled by servlet filters if needed.

4. **Single-instance lifecycle.** Like all servlets, `FacesServlet` is instantiated once per web application. Any state stored as instance variables must be thread-safe.

5. **Multiple deployment descriptors.** The presence of both `web.xml` and `web-full.xml` means this project targets both standard and full Java EE profiles. Ensure both files define consistent servlet mappings to avoid divergent behavior across profiles.

6. **No source files indexed at parent level.** The `javax` module itself contains no indexed source files, classes, or methods — all symbols are defined within its sub-packages, primarily `javax.faces.webapp`. This reflects the stub nature of the codebase at this stage.