# Javax

## Overview

The `javax` namespace in this codebase appears to be a minimal stub or documentation scaffold for **Java EE / Jakarta EE** packages, specifically the `javax.faces` JSF (JavaServer Faces) web framework. No source files have been indexed under this module, and no classes, interfaces, or methods have been captured in the index — meaning the actual implementation source is not present in this project.

What does exist is documentation (see `javax/faces.md`) describing the `javax.faces` namespace, which represents the top-level API surface for building server-driven, component-based user interfaces in Java EE applications. The codebase itself appears to be a documentation or code-analysis project rather than an application that uses or implements JSF.

This area of the codebase represents the **public API surface** of the JSF framework — the classes, interfaces, and annotations that application developers interact with. The framework follows the Model-View-Controller (MVC) pattern and provides a stack-based component model where server-side UI components are rendered to HTML (or other formats) and wired to backing beans through a declarative six-phase lifecycle.

## Sub-module Guide

### `javax.faces`

The `javax.faces` package (documented in the child page) is the top-level namespace for JavaServer Faces. It encompasses:

- **Core API classes** — lifecycle management, context handling, component tree architecture, and the `FacesContext` per-request state object.
- **Web integration** — the `javax.faces.webapp` subpackage, which contains the `FacesServlet` that acts as the front controller for all JSF requests.

The `webapp` subpackage serves as the bridge between the servlet container and the JSF runtime. When an HTTP request matches the configured URL pattern (e.g., `*.jsf`), the `FacesServlet` creates a `FacesContext`, runs the request through the six-phase lifecycle, renders the response, and cleans up. The other `javax.faces` subpackages (such as `javax.faces.context`, `javax.faces.lifecycle`, and `javax.faces.component`) handle the actual work delegated by the servlet.

**Relationship:** The `webapp` subpackage is the *entry point* into the `javax.faces` namespace. It has no business logic of its own beyond servlet integration — it delegates to the core lifecycle and component packages. This creates a clean separation: web integration lives in `webapp`, while component model, validation, event handling, and rendering live in the core subpackages.

## Key Patterns and Architecture

### Front Controller Pattern

The `FacesServlet` implements the front controller pattern: a single servlet receives all JSF requests and dispatches them through a canonical pipeline. This centralizes request handling, makes URL routing declarative (via `web.xml`), and ensures every request follows the same lifecycle regardless of entry point.

### Six-Phase Lifecycle

Each JSF request flows through six distinct phases, each with its own responsibility:

1. **Restore View** — Reconstructs the component tree from saved state, or creates a fresh tree.
2. **Apply Request Values** — Populates component local values from request parameters.
3. **Process Validations** — Runs registered validators against component values.
4. **Update Model Values** — Writes validated values into backing bean properties.
5. **Invoke Application** — Fires application-level events (e.g., button action handlers).
6. **Render Response** — Walks the component tree and renders the output.

This phased approach separates concerns cleanly: input collection, validation, business logic, and output rendering happen in distinct steps, each with its own error-handling exit points.

### Component Tree Model

JSF uses a tree of server-side UI component objects to represent the page. The `UIViewRoot` serves as the root of this tree, with child components organized hierarchically. A pluggable render kit architecture decouples component logic from presentation — the default is HTML, but other formats (WML, XHTML, PDF) are supported.

### Per-Request Context

Each request receives its own `FacesContext` instance, holding request-scoped state including parameter maps, view references, and locale. The lifecycle manages creation and cleanup, ensuring no state leaks between requests.

```mermaid
flowchart LR
    Browser["Browser / Client"] -->|HTTP request| WebXML["web.xml
URL mapping"]
    WebXML --> FacesServlet["FacesServlet
javax.faces.webapp"]
    FacesServlet --> FacesContext["FacesContext
per-request state"]
    FacesContext --> Lifecycle["JSF Lifecycle
6 phases"]
    Lifecycle --> ComponentTree["Component Tree
UIViewRoot + children"]
    ComponentTree --> RenderKit["Render Kit
HTML output"]
    RenderKit -->|HTTP response| Browser
```

## Dependencies and Integration

The `javax.faces` package connects to the broader ecosystem as follows:

- **Servlet API (`javax.servlet.*`)** — The web layer depends on the servlet container for HTTP handling. `FacesServlet` extends `HttpServlet`.
- **Deployment descriptors (`web.xml`, `web-full.xml`)** — The `FacesServlet` is registered and mapped in standard Java EE web descriptors, tying the framework into the application server's request routing.
- **Backing beans** — JSF components bind to managed beans (or CDI beans in modern deployments) through EL expressions, giving the framework access to application state and business logic.
- **Render kits** — Custom renderers and render kits can replace the default HTML output, enabling non-browser clients or alternative markup formats.

Because no source files are indexed in the current project, no programmatic dependency analysis is available. The integration points above are documented at the specification level in the `javax.faces.webapp` documentation.

## Notes for Developers

- This codebase does not contain actual JSF source code. The `javax` namespace appears to be a documentation scaffold. If you are implementing or extending JSF classes, refer to the [Jakarta Faces specification](https://jakarta.ee/specifications/faces/) for the complete API.
- The `javax.faces` namespace is the **Java EE** variant. In Jakarta EE 9+ (JSF 3.x+), the package was renamed to `jakarta.faces.*`. Migration between the two requires namespace replacement across all imports and deployment descriptors.
- URL mapping is the primary configuration point for controlling which requests JSF processes. This is defined in the deployment descriptor, not in code.
- The `FacesServlet` registration appears in both `web.xml` and `web-full.xml`, meaning the servlet is set up through the standard Java EE web deployment mechanism — no custom bootstrap code is required beyond what the application server handles.
- Memory management is critical: the `FacesServlet` must clean up the `FacesContext` after each request to avoid leaks.