# Com / Fujitsu

## Overview

The `com.fujitsu` package is a top-level package (rooted directly under the `com` namespace) with no indexed source files or classes captured in the module index. Its only documented child is the `com.fujitsu.futurity` subpackage, which represents the web-tier boundary of the **Futurity** application -- a Fujitsu-associated web application.

This package appears to be an integration layer between a Java servlet container (such as Tomcat or WebSphere) and the internal business logic of the Futurity system. Its responsibilities include managing servlet container lifecycles and shaping incoming HTTP requests -- particularly for Japanese-language requests requiring Shift JIS (SJIS) character encoding.

At present, the package and its sub-modules are in a **scaffolding state**: the structural classes and XML deployment descriptors are in place, but the functional logic within them is not yet implemented. This is typical of large enterprise codebases where infrastructure hooks are created ahead of feature implementation, or where components were once functional and have since been retired without cleanup.

## Sub-module Guide

### Futurity (`com.fujitsu.futurity`)

The `com.fujitsu.futurity` subpackage is the sole documented child module under `com.fujitsu`. It serves as the web-layer entry point for the Futurity application, exposing servlet extension points (filters and listeners) that the container wires up via `web.xml` and `web-full.xml` configuration.

Within `futurity`, the primary sub-module is:

#### x33 (`com.fujitsu.futurity.web.x33`)

The `x33` sub-package provides the web-layer hooks specific to the **X33 module** of Futurity. It contains two complementary components that operate in a temporal lifecycle chain:

- **X33JVRequestEncodingSjisFilter** -- An HTTP request filter 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 intended to fire on application startup and shutdown for setting up and tearing down application-global state. The class body is currently empty.

**Relationship between sub-modules:** The `futurity` package provides the overarching web-tier structure, while `x33` specializes within it for the X33-specific module's encoding and lifecycle needs. In a fully implemented system, the listener would configure application-global state (such as encoding preferences) at deployment time, and the filter would read that configuration during every incoming request. Currently, no coupling exists between the two components -- they operate in complete isolation from each other and from the rest of the Futurity domain code.

```mermaid
flowchart TD
    A["com.fujitsu - Fujitsu Package Root"] --> B["com.fujitsu.futurity - Futurity"]
    B --> C["com.fujitsu.futurity.web - Web Infrastructure"]
    C --> D["com.fujitsu.futurity.web.x33 - X33 Module"]
    D --> E["X33JVRequestEncodingSjisFilter"]
    D --> F["X33AppContextListener"]
    subgraph X33Group["x33 sub-package"]
        E
        F
    end
```

## 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 / web-full.xml"]
    B --> C["X33AppContextListener"]
    B --> D["X33JVRequestEncodingSjisFilter"]
    C --> E["ServletContext"]
    D --> F["FilterChain"]
    E --> G["Application Context"]
    F --> H["Target Servlets"]
```

### Stub Architecture

The dominant architectural pattern across this package is **stub architecture**. The classes exist, the XML registrations are in place, but the logic is absent. 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. The servlet container is the only thing that currently "knows" these components exist.

### Request-Response Pipeline (Planned)

When fully implemented, the expected lifecycle flow is:

1. **Startup:** `X33AppContextListener.contextInitialized()` fires, setting up application-global state (e.g., encoding configuration).
2. **Per-request:** `X33JVRequestEncodingSjisFilter.doFilter()` runs on every incoming request, applying Shift JIS encoding before delegating to target servlets.
3. **Shutdown:** `X33AppContextListener.contextDestroyed()` fires during undeployment, cleaning up application-global state.

## Dependencies and Integration

### External Dependencies

| Dependency | Role |
|---|---|
| `javax.servlet.Filter` | Interface intended 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 any component in the `com.fujitsu` hierarchy. The components are wired exclusively through XML configuration (`web.xml` and `web-full.xml`). No other module imports or depends on these components.

### Inbound Dependencies (Deployment)

- **`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 Shift JIS 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 Shift JIS 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 Shift JIS 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.