# Com / Fujitsu / Futurity / Web

## Overview

The `com.fujitsu.futurity.web` package is the servlet-layer entry point for the Fujitsu Futurity web application. It provides the foundational infrastructure that sits between the servlet container (Tomcat, WebSphere, or equivalent) and the application's business logic — specifically the Jakarta EE / JSF rendering layer.

This area of the codebase is responsible for:

- **Application lifecycle management** — receiving startup and shutdown callbacks so the application can initialize shared state.
- **Request pre-processing** — intercepting every incoming HTTP request through a servlet filter chain for tasks like character encoding, authentication, and logging.

The application targets a Japanese locale, as evidenced by the Shift-JIS (MS932) encoding conventions used throughout the servlet filter infrastructure.

While the package itself contains no indexed source files at the top level, it hosts sub-packages that implement the standard Java EE servlet lifecycle archetypes. The primary sub-package is `x33`, which provides both a `ServletContextListener` for startup/shutdown hooks and a `Filter` for per-request preprocessing.

## Sub-module Guide

### x33 — Servlet Lifecycle Infrastructure

The `com.fujitsu.futurity.web.x33` package is the only sub-module under the web package. It contains two components that form the application's request and lifecycle entry points:

| Component | Class | Purpose |
|---|---|---|
| **Listener** | `X33AppContextListener` | Application-wide startup/shutdown hooks |
| **Filter** | `X33JVRequestEncodingSjisFilter` | Per-request preprocessing (character encoding) |

**How they work together:**

The listener and filter operate at different boundaries of the servlet lifecycle:

- The **listener** fires once at application startup (`contextInitialized`) and once at shutdown (`contextDestroyed`). It is the place where application-wide state — such as Spring context initialization, shared caches, or background service registration — should be set up. This currently does nothing (empty stub), meaning any shared services must be initialized through other mechanisms (e.g., Spring configuration or the FacesServlet itself).

- The **filter** fires for every HTTP request that matches its `<filter-mapping>`. It sits between the servlet container and the FacesServlet, processing requests before they reach the JSF rendering layer. The filter's name implies it was designed to set the request character encoding to Shift-JIS (MS932) for proper Japanese text handling, but its current implementation is a no-op — it forwards every request unmodified.

**Deployment model:**

Both components are registered entirely through `web.xml` and `web-full.xml` (XML-based deployment descriptors). There is no use of `@WebListener` or `@WebFilter` annotations, which is consistent with a traditional Java EE (pre-Servlet 3.0) configuration style or a project that prioritizes container-portable descriptor-based configuration.

## Key Patterns and Architecture

### Request and lifecycle flow

The following diagram shows how requests and lifecycle events flow through this module:

```mermaid
flowchart TD
    A["Servlet Container
(Tomcat, WebSphere)"] -->|"startup"| B["X33AppContextListener
contextInitialized"]
    A -->|"shutdown"| C["X33AppContextListener
contextDestroyed"]
    A -->|"HTTP request"| D["X33JVRequestEncodingSjisFilter
doFilter"]
    D -->|"chain.doFilter"| E["Next filter / FacesServlet
(JSF view rendering)"]
    style B fill:#ff9
    style C fill:#f99
    style D fill:#9cf
    style E fill:#9f9
```

### Current state: no-op infrastructure

Both components in the x33 sub-package are currently empty stubs. The practical implications are:

- **No startup initialization:** When the application starts, no application-wide state is set up by this listener. Downstream components expecting shared services or configuration must initialize them through other paths (Spring, JSF managed beans, or the FacesServlet itself).

- **No per-request processing:** Incoming requests pass through the filter chain unmodified. If Japanese character encoding support is required, it is not being handled here — the servlet container or JSF runtime would need separate configuration for this.

This pattern suggests one of three possibilities: the X33 application is an early scaffold, a legacy module whose implementation was removed over time, or a placeholder for future servlet-level functionality that was never fully realized.

### Servlet lifecycle archetype

The pair of a `ServletContextListener` and a `Filter` is a well-established Java EE pattern. The listener handles the application lifecycle boundary (one-time setup/teardown), while the filter handles the per-request boundary (cross-cutting concerns like encoding, logging, or authentication). This separation of concerns is architecturally sound; it is the absence of implementation in both components that is notable.

## Dependencies and Integration

| Dependency | Details |
|---|---|
| **`web.xml` / `web-full.xml`** | Deployment descriptors register both the listener (`<listener>`) and filter (`<filter>` + `<filter-mapping>`) |
| **Jakarta Servlet API** | Uses `javax.servlet.Filter`, `javax.servlet.ServletContextListener`, `javax.servlet.FilterChain`, `javax.servlet.ServletRequest`, `javax.servlet.ServletResponse`, `javax.servlet.FilterConfig` |
| **JSF (FacesServlet)** | The FacesServlet is the next servlet in the filter chain, responsible for rendering JSF-based views |
| **Servlet container** | Tomcat, WebSphere, or equivalent — reads `web.xml`, instantiates the listener, and routes requests through the filter chain |

### Data flow

1. The servlet container starts up and reads `web.xml`.
2. It instantiates `X33AppContextListener` and calls `contextInitialized()` — currently a no-op.
3. When an HTTP request arrives matching the filter's `<filter-mapping>`, the container calls `X33JVRequestEncodingSjisFilter.doFilter()`.
4. The filter immediately delegates to the next chain element (`chain.doFilter(req, res)`).
5. The request eventually reaches the FacesServlet for JSF view rendering.

### Cross-module connections

No other application modules were detected as directly importing from or being imported by this package. The integration points are entirely through the deployment descriptors and the servlet container's lifecycle — this module is self-contained at the source level, acting as a transparent pass-through to the rest of the application.

## Notes for Developers

### Name vs. behavior mismatch (filter)

`X33JVRequestEncodingSjisFilter` strongly implies Shift-JIS character encoding support but currently does nothing. If Japanese text handling is required:

- Add `req.setCharacterEncoding("MS932")` as the first line of `doFilter()`.
- Consider adding `<init-param>` elements in `web.xml` for configurable encoding.
- Evaluate whether the encoding filter should also handle response content type headers.

### Empty stub warning (listener)

`X33AppContextListener` is registered but performs no operations. If your application expects application-wide initialization to occur by the time the first request arrives (e.g., Spring context, shared caches), verify whether that initialization was intended to live in this listener. An unimplemented context listener is the most likely cause of `NullPointerException` or missing service errors at startup.

### Thread safety

Both classes hold no instance state, making them inherently thread-safe today. Any future state added to these classes should be carefully designed for thread safety — particularly `X33JVRequestEncodingSjisFilter`, which handles every incoming request.

### Migration to modern patterns

This package uses the legacy `javax.servlet` API and XML-based registration. If the project migrates to Jakarta EE 9+, the package namespace and annotations would need updating. The descriptor-based approach, however, remains fully valid and portable across containers.

### Extension points

- The **listener** (`X33AppContextListener`) is the intended entry point for application-wide startup logic. Any new infrastructure — caching, background jobs, monitoring — should be initialized in `contextInitialized()`.
- The **filter** (`X33JVRequestEncodingSjisFilter`) is the intended place for per-request cross-cutting concerns (encoding, logging, authentication, CORS headers). Be aware that adding logic here affects every single HTTP request, so performance implications should be considered.