# Com / Fujitsu

## Overview

The `com.fujitsu` package serves as the root namespace for the **Fujitsu Futurity application**, a Java EE web application. At this level, the codebase represents structural scaffolding — the package hierarchy is defined, class names are descriptive, and deployment descriptor registrations are in place, but the substantive business logic and runtime behavior are still being built out.

This appears to be a greenfield or early-stage module. The architectural skeleton has been laid down, with the most concrete work concentrated in the `com.fujitsu.futurity.web` sub-package, which forms the web-tier integration layer between the servlet container and the application's backend subsystems. The primary implemented concern is the **X33 web integration subsystem** — a Japanese-facing component requiring Shift-JIS (MS932) character encoding on incoming requests.

## Sub-module Guide

The `com.fujitsu` package currently contains one documented child module:

### `com.fujitsu.futurity` — The Futurity Application

This is the root package for the Futurity application itself. It contains a single major sub-package:

- **`com.fujitsu.futurity.web`** — The outermost web-facing package, handling all HTTP-level concerns (request dispatching, character encoding, and lifecycle event management) before traffic reaches downstream service layers. The `web-full.xml` deployment descriptor acts as the source of truth for servlet wiring, rather than relying on Spring or annotation-based auto-discovery.

Within the `web` package, the `x33` sub-package is the only implemented slice, split into two complementary areas:

- **`com.fujitsu.futurity.web.x33.filter`** — Contains `X33JVRequestEncodingSjisFilter`, a servlet filter that intercepts incoming HTTP requests for the X33 JV endpoint group. Its purpose is to enforce **Shift-JIS (MS932) encoding** on request parameters, form data, and headers — a critical requirement for Japanese web applications handling multi-byte characters. Currently, this is a pass-through no-op that delegates directly to the filter chain without modification.

- **`com.fujitsu.futurity.web.x33.listener`** — Contains `X33AppContextListener`, a class stub meant to serve as a servlet context listener for X33-specific startup and shutdown lifecycle management. Currently an empty class with no implementation, no `implements` clause, no annotations, and no container registration.

### How the sub-modules relate

The relationship across the `com.fujitsu` hierarchy follows a top-down delegation model:

```mermaid
flowchart TD
    A["Futurity Application"] --> B["X33 Integration Subsystem"]
    B --> C["Request Encoding Filter"]
    B --> D["Application Lifecycle Listener"]
    B --> E["Deployment Descriptor web-full.xml"]
    C --> F["Shift-JIS / MS932 Encoding"]
    C --> G["Filter Chain Processing"]
    D --> H["Context Initialization"]
    D --> I["Shared Resource Management"]
    E --> C
    E --> D
    F --> J["Backend Subsystems"]
    G --> J
    H --> J
    I --> J
```

The filter and listener sub-packages serve complementary roles in the X33 web subsystem's request lifecycle:

| Sub-package | Lifecycle scope | Responsibility |
|---|---|---|
| `listener` | Application-wide | Startup, shutdown, context attribute events |
| `filter` | Per-request | Character encoding on incoming HTTP requests |

In a fully implemented system, the listener would initialize shared resources at application startup (e.g., connection pools, configuration lookups), and the filter would ensure every incoming X33 request is processed with the correct Shift-JIS encoding before reaching the backend subsystem. Together, they form the two fundamental axes of the web-tier request lifecycle — initialization and per-request processing. The `web-full.xml` deployment descriptor acts as the glue between the servlet container and both sub-modules, declaring the filter registration and URL mappings that wire these classes into the request processing pipeline.

## Key Patterns and Architecture

### Package Hierarchy

The module's package structure reflects a clean separation of web-tier concerns:

```mermaid
flowchart TD
    A["com.fujitsu.futurity root package"] --> B["com.fujitsu.futurity.web web-tier"]
    B --> C["com.fujitsu.futurity.web.x33 X33 integration"]
    C --> D["com.fujitsu.futurity.web.x33.filter"]
    C --> E["com.fujitsu.futurity.web.x33.listener"]
    D --> F["X33JVRequestEncodingSjisFilter"]
    E --> G["X33AppContextListener"]
    B --> H["web-full.xml deployment descriptor"]
    F --> I["javax.servlet.Filter chain processing"]
    G --> J["ServletContext lifecycle awaiting implementation"]
```

### Registration-based Wiring (XML-Declarative)

Both the filter and listener rely on **declarative registration** through `web-full.xml` rather than annotations. The filter is declared and mapped to URL patterns in the deployment descriptor. If the listener were implemented, it would similarly be declared in `web.xml` (or annotated with `@WebListener`). This reflects the application's use of a traditional Java EE deployment model where the deployment descriptor is the source of truth for servlet wiring.

### Filter Chain Architecture

The `x33/filter` sub-package follows the standard `javax.servlet.Filter` pattern with three lifecycle methods (`doFilter`, `init`, `destroy`). The filter chain architecture allows multiple filters to be stacked, each able to inspect, modify, or short-circuit the request before it reaches the target servlet. Currently, `X33JVRequestEncodingSjisFilter` delegates directly to the next link in the chain without any processing.

### Placeholder (Scaffold) Pattern

The entire `com.fujitsu.futurity.web` module follows a scaffold pattern — class names, package structure, and registrations are in place, but the behavior is not yet implemented. This suggests one of:

1. The X33 web integration work was started but not completed.
2. The encoding and listener concerns are handled elsewhere in the application (e.g., a global character encoding filter or Spring-based lifecycle beans), making these X33-specific placeholders temporary.

### Inferred Request Flow

When the application is fully implemented, the request flow through the web tier is expected to follow this pattern:

```mermaid
flowchart LR
    A["Client"] -->|HTTP request| B["web-full.xml"]
    B -->|routes to filter| C["X33JVRequestEncodingSjisFilter"]
    C -->|applies SJIS encoding| D["Encoding wrapper"]
    D -->|forwarded downstream| E["X33 backend subsystem"]
    F["ServletContext startup"] -->|initializes resources| G["X33AppContextListener"]
    G -->|shared config and pools| E
```

### Thread Safety

The filter is thread-safe by design — it holds no instance fields and is entirely stateless. No synchronization is needed for concurrent request handling.

## Dependencies and Integration

### External Dependencies

| Dependency | Role |
|---|---|
| `javax.servlet.Filter` | Implemented by `X33JVRequestEncodingSjisFilter` for `doFilter`, `init`, and `destroy` methods |
| `javax.servlet.ServletRequest` / `ServletResponse` | Types used in `doFilter()` for request/response handling |
| `javax.servlet.FilterChain` | Used by the filter to pass requests down the chain |
| `web-full.xml` | Declares the filter registration and associates it with URL patterns |

### Internal Relationships

No internal application package dependencies have been detected. This module does not import or reference any classes from other parts of the Futurity codebase. It is a **leaf module** at the `com.fujitsu.futurity.web.x33` level, meaning it is designed to be the outermost web-facing layer for the X33 subsystem — it receives external traffic and delegates inward.

### Cross-Module Integration

No cross-module relationships were detected in the index. If the listener were implemented (e.g., as a `ServletContextListener`), it would naturally integrate with the broader application lifecycle — potentially initializing beans, registering JNDI resources, or triggering X33-specific startup routines. As-is, it does not participate in any request flow or event handling.

## Notes for Developers

### Encoding Is Not Applied

The `X33JVRequestEncodingSjisFilter` does not set any character encoding on incoming requests. If the X33 JV subsystem handles Japanese input (Shift-JIS / MS932), requests may arrive with incorrect character encoding, potentially corrupting multi-byte characters in parameters or headers.

**Recommended next steps:**

- Verify with the team whether this filter should (a) implement the SJIS encoding logic, (b) delegate encoding to a site-wide `CharacterEncodingFilter`, or (c) be removed entirely.
- If encoding should be applied, `req.setCharacterEncoding("MS932")` should be called before `chain.doFilter(...)` in `doFilter()`.

### Listener Is a Stub

`X33AppContextListener` has no implementation and is not registered with the servlet container. If X33 requires any startup or shutdown logic, this class is the intended location — but it needs to be:

1. Wired to an appropriate listener interface (`ServletContextListener`, `HttpSessionListener`, etc.).
2. Annotated with `@WebListener` or registered in `web.xml`.
3. Implemented with the actual initialization or cleanup logic.

### Configuration Extensibility

The filter's `init(FilterConfig)` method ignores its `config` parameter. If encoding rules ever need to become configurable (e.g., selectable character sets per deployment environment), the `init` method would be the extension point to read initialization parameters from the deployment descriptor.

### General Guidance

- The entire module is currently scaffolding. Before implementing behavior, coordinate with the team to understand whether X33-specific encoding and lifecycle handling is still needed, or if it has been superseded by application-wide mechanisms.
- Any new code should follow the existing XML-declarative wiring pattern for consistency with the deployment model.
- Character encoding is a critical concern for the X33 subsystem. Misconfigured encoding in production could silently corrupt user input — prioritize verifying and implementing the filter's encoding logic.