# Com / Fujitsu / Futurity / Web

## Overview

The `com.fujitsu.futurity.web` package represents the web-tier boundary of the Futurity application — the integration seam between the servlet container (e.g., Tomcat, WebSphere) and the application's internal business logic. It is responsible for managing the servlet container lifecycle and shaping incoming HTTP requests before they reach the core application layers.

This area of the codebase currently serves as **infrastructure scaffolding** rather than active functionality. The package contains a single child module, `x33`, which provides container-managed extension points (a filter and a context listener) that are registered in `web.xml` but have no functional implementation today. When fully realized, this package will control how the application handles its startup/shutdown behavior and how it processes incoming character encoding for requests.

## Sub-module Guide

### x33 — X33 Module Web Infrastructure

The `x33` sub-package provides the web-layer hooks specific to the X33 module of Futurity. It consists of two complementary components that follow the Java EE servlet lifecycle pattern:

- **`X33JVRequestEncodingSjisFilter`** — an HTTP request filter registered in both `web.xml` and `web-full.xml`. Its name suggests it was intended to handle Shift JIS character encoding for Japanese-language requests, a common requirement in Japanese enterprise applications. Currently, its `doFilter` method simply delegates every request to the next element in the chain without any transformation.

- **`X33AppContextListener`** — a `ServletContextListener` registered in `web.xml` to fire on application startup and shutdown. The class body is currently completely empty with no interface implementation or methods. When implemented, it will serve as the entry point for application-wide setup tasks (bootstrapping contexts, initializing pools, loading configuration) and cleanup on shutdown.

#### How the Sub-modules Relate

Both components are **container-managed extension points** — they are the mechanisms by which the servlet container reaches into the application. They relate to each other in a temporal chain:

1. **Listener fires first** — when the container deploys the application, the listener's `contextInitialized()` is called before any servlets or filters are touched. This is where global setup happens.
2. **Filter fires on every request** — after the application is running, the filter's `doFilter()` is invoked for each matching incoming HTTP request.
3. **Listener fires last** — on undeploy, `contextDestroyed()` handles cleanup.

In a fully implemented system, the listener would set up shared state (e.g., encoding configuration, context beans) that the filter then references during request processing. Currently, neither exists, so no interaction is possible.

## Key Patterns and Architecture

### Container-Managed Lifecycle

Both components follow the Java EE servlet lifecycle pattern — the container creates instances and invokes lifecycle methods. Neither component manages its own instantiation; the container does so via XML registration. This is the classic "convention over configuration" approach of servlet-based applications.

```mermaid
flowchart TD
    A["Servlet Container"] --> B["web.xml"]
    B --> C["X33AppContextListener"]
    B --> D["X33JVRequestEncodingSjisFilter"]
    C --> E["ServletContext"]
    D --> F["FilterChain"]
    E --> G["Application Context"]
    F --> H["Target Servlets"]
    subgraph X33["com.fujitsu.futurity.web.x33"]
        C
        D
    end
```

### Request-Response Pipeline

When these components are implemented, the expected request flow will proceed as follows:

```mermaid
sequenceDiagram
    participant C as Container
    participant L as X33AppContextListener
    participant F as X33JVRequestEncodingSjisFilter
    participant S as Target Servlet
    Container->>L: contextInitialized
    L-->>C: completes
    loop Each Request
        Container->>F: doFilter
        F->>S: chain.doFilter
        S-->>F: response
        F-->>C: response
    end
    Container->>L: contextDestroyed
```

### Stub Architecture

At present, both components follow a **stub architecture** pattern — the classes exist, the registrations are in place, but the logic is absent. This is a common pattern in large enterprise codebases where infrastructure scaffolding is created ahead of implementation, or where components were implemented and later retired without cleanup. Neither component imports or references any internal Futurity classes, meaning the package currently operates in complete isolation from the rest of the application's domain code.

## Dependencies and Integration

### External Dependencies

| Dependency | Role |
|---|---|
| `javax.servlet.Filter` | Interface implemented by `X33JVRequestEncodingSjisFilter` |
| `javax.servlet.ServletContextListener` | Interface intended for `X33AppContextListener` (not yet implemented) |
| `javax.servlet.*` | Broader Servlet API used for request/response objects and configuration |

### Internal Dependencies

No internal Futurity classes are imported or referenced from either component. The X33 web package currently operates in complete isolation from the rest of the application's domain code.

### Inbound Dependencies

Both components are referenced by `web.xml`:

- **`X33AppContextListener`** is registered as a `<listener>` entry.
- **`X33JVRequestEncodingSjisFilter`** is registered as a `<filter>` and mapped to URL patterns via `<filter-mapping>`.
- The filter also appears in `web-full.xml`, the Java EE "full" profile variant, suggesting the application may run on servers that use that profile (e.g., WebSphere).

This means the container is the only thing that currently "knows" these components exist. No other module imports them.

## Notes for Developers

### This is currently dead code

Both `X33JVRequestEncodingSjisFilter` and `X33AppContextListener` have no functional behavior. If the X33 module depends on SJIS encoding support or on any startup initialization wired through this listener, it is **not happening** in the current state.

### Key risks if implementing

1. **Character encoding** — If SJIS encoding is still needed, implementing `req.setCharacterEncoding("SJIS")` in the filter may have broader implications. Modern applications typically use UTF-8. Confirm with stakeholders whether Shift JIS is still a requirement before proceeding.

2. **Listener visibility** — `X33AppContextListener` is package-private. If the container needs to instantiate it via `web.xml`, it must be `public`. A deployment-time `ClassNotFoundException` is a common and easily overlooked failure mode.

3. **XML consistency** — The filter is declared in both `web.xml` and `web-full.xml`. If an application server loads one but not the other, the filter may or may not be active depending on which config the server prefers.

4. **Shared state** — If the listener is implemented to set up application-global configuration, the filter may need to read that configuration. This creates a coupling between the two components that does not currently exist — plan for it if needed.

5. **Thread safety** — Both components are single-instance, container-managed. Any state added to them must be thread-safe (for the filter, which processes concurrent requests) or single-threaded (for the listener, which runs only during init/shutdown on a single thread).

6. **Extensibility** — Both implement standard servlet interfaces, so they can be enhanced without breaking any integration points. The filter can be populated with logic before the `chain.doFilter()` call. The listener can implement `contextInitialized` and `contextDestroyed`.

### Recommended first steps

If the goal is to bring this module to a functional state:

1. **Decide on encoding** — Confirm whether SJIS or UTF-8 is the target encoding for the X33 module.
2. **Make the listener public** — Change `X33AppContextListener` visibility to `public` to prevent deployment failures.
3. **Implement `ServletContextListener`** — Add the interface and at least a no-op `contextInitialized` method.
4. **Wire up shared state** — If the filter needs configuration from the listener, decide on the data-passing mechanism (e.g., `ServletContext` attributes).
5. **Populate the filter** — Implement the encoding logic in `doFilter` before the chain delegation.