# Com / Fujitsu / Futurity

## Overview

The `com.fujitsu.futurity` package represents the top-level web-tier boundary of the Futurity application. It serves as the integration seam between the servlet container (e.g., Tomcat, WebSphere) and the application's internal business logic. Its primary responsibility is to manage the servlet container lifecycle and shape incoming HTTP requests before they reach the core application layers.

At present, this package functions as **infrastructure scaffolding** rather than a fully realized subsystem. It provides the registration points and extension hooks — a filter for request encoding and a context listener for application startup/shutdown — but neither hook contains functional logic today. When implemented, the package will control how the application handles its startup behavior, its shutdown cleanup, and its character encoding for incoming Japanese-language requests (Shift JIS).

## Sub-module Guide

### web — Web Infrastructure Scaffolding

The `web` sub-package is the sole child module under `com.fujitsu.futurity` and contains all web-layer concerns for the Futurity application. Its job is to expose servlet container extension points (filters and listeners) that the container wires up via `web.xml` and `web-full.xml` configuration.

At present, `web` contains a single child module:

#### 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 registered in the application's XML configuration:

- **X33JVRequestEncodingSjisFilter** — An HTTP request filter that was intended to enforce Shift JIS character encoding on incoming requests. Currently, its `doFilter` method simply delegates every request through the filter chain without any transformation.

- **X33AppContextListener** — A `ServletContextListener` placeholder registered in `web.xml` to fire on application startup and shutdown. The class body is currently empty with no methods or interface implementation.

These two components operate in a temporal lifecycle chain: the listener fires first at deployment (initialization), the filter runs on every incoming request while the application is active, and the listener fires last on undeployment (cleanup). In a fully implemented system, the listener would set up application-global state (e.g., encoding configuration, shared beans) that the filter would then reference during request processing.

## Key Patterns and Architecture

### Container-Managed Lifecycle

Both components in the `x33` sub-package follow the Java EE servlet lifecycle pattern. Neither component manages its own instantiation; the servlet container creates instances and invokes lifecycle methods based on XML registration. This is the classic "convention over configuration" approach used by `web.xml`-based Java web 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 fully implemented, the expected lifecycle flow for the `x33` sub-package is:

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

### Stub Architecture

At present, both components follow a **stub architecture** pattern. The classes exist, the XML 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 in the `web` package. Both components are wired exclusively through XML configuration (`web.xml` and `web-full.xml`). This means the servlet container is the only thing that currently "knows" these components exist. No other module imports them, and no other module depends on them.

### Inbound Dependencies

Both components are referenced by deployment descriptors:

- **`X33AppContextListener`** is registered as a `<listener>` entry in `web.xml`.
- **`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 deploy on servers that prefer that profile (e.g., WebSphere).

This dual-registration means configuration consistency between the two XML files is important; a server that loads one but not the other may behave differently depending on which config takes precedence.

## 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.