# Com / Fujitsu

## Overview

The `com.fujitsu` package is the top-level Java namespace for all Fujitsu-related code in this codebase. It functions as an organizational boundary — a corporate-level grouping rather than a cohesive application module with internal logic. At present, its only documented child is `com.fujitsu.futurity`, which itself is a Java EE web application scaffolding targeting Japanese-language HTTP workflows.

In practical terms, this package does not contain business logic, shared utilities, or cross-cutting infrastructure. It is a leaf in the dependency graph: no other package imports from `com.fujitsu`, and `com.fujitsu` itself depends only on `javax.servlet`. This means changes here are isolated — they have no downstream ripple effects across the codebase.

## Sub-module Guide

### `futurity` — Japanese-Targeted Web Application

The `futurity` sub-package is the sole documented child of `com.fujitsu`. It is a Java EE web application (with an explicit `x33` variant) designed to serve HTTP-based workflows for Japanese-language users. The application follows a standard Java EE servlet architecture, with its web tier (`com.fujitsu.futurity.web`) declaring lifecycle and request-level hooks through deployment descriptors rather than code.

Key characteristics:

- **Japanese localization intent.** The filter `X33JVRequestEncodingSjisFilter` is designed to handle Shift JIS (SJIS / cp932) encoding, indicating the application targets Japanese-language input. This is currently unimplemented, which poses a risk of mojibake (garbled text) if the server's default encoding is not SJIS-compatible.
- **Scaffolding phase.** Both the application listener and request filter are no-op stubs. The module appears to be in early planning or was reserved as an extension point ahead of active sprint work.
- **Minimal dependency footprint.** Only `javax.servlet` is imported. No Spring, CDI, or other frameworks are wired in, leaving the decision about the application context model (pure servlet vs. Spring-integrated) still open.

## Key Patterns and Architecture

### Deployment Descriptor-Driven Registration

Rather than using Java EE annotations (`@WebListener`, `@WebFilter`), the Futurity module registers its components entirely through `web.xml` and `web-full.xml`. This dual-registration across both the servlet-only and full Java EE profiles ensures the hooks activate regardless of whether the application runs on a lightweight container (Tomcat) or a full Jakarta EE server.

### Scaffold / Stub Pattern

The entire `com.fujitsu` module follows a "declare the hook, leave the body empty" pattern. The listener and filter exist in the compiled codebase but perform zero work at runtime. This is a common practice when reserving extension points — it allows deployment-time validation of descriptors and ensures the container won't error on missing classes.

### Request Processing Pipeline

```mermaid
flowchart TD
    subgraph DEP["Deployment Descriptors"]
        WD["web.xml / web-full.xml"]
    end

    subgraph STAGE1["Startup Phase"]
        regL["Registers X33AppContextListener"]
    end

    subgraph STAGE2["Request Phase"]
        regF["Registers X33JVRequestEncodingSjisFilter"]
    end

    DEP --> regL
    DEP --> regF
    regL --> emptyL["Empty stub - no-op"]
    regF --> emptyF["Delegates to chain - no-op"]
```

The servlet pipeline proceeds in two distinct phases:

```mermaid
sequenceDiagram
    autonumber
    participant C as "Servlet Container"
    participant L as "X33AppContextListener"
    participant RQ as "X33JVRequestEncodingSjisFilter"
    participant FC as "FilterChain"
    participant S as "Target Servlet"

    C->>L: contextInitialized event
    activate L
    note right of L: No-op: empty class body
    deactivate L
    loop "For each HTTP request"
        C->>RQ: request arrives
        activate RQ
        RQ->>FC: chain.doFilter req, res
        RQ->>RQ: returns immediately
        deactivate RQ
        FC->>S: pass through unchanged
        S-->>C: response
    end
```

1. **Startup.** The container fires a single `contextInitialized` event to the application listener. Today this fires but does nothing; once implemented, it would bootstrap configuration, resource pools, or Spring context initialization.
2. **Request routing.** Every HTTP request passes through the encoding filter before reaching its target servlet. Today the filter is transparent — it delegates immediately without modifying the request — but once implemented, it would normalize character encoding before business logic processes the parameters.

### Package Structure

```
com.fujitsu.futurity.web
└─── x33
    ├─── listener/
    │   └─── X33AppContextListener.java      — empty lifecycle stub
    └─── filter/
        └─── X33JVRequestEncodingSjisFilter.java  — no-op request filter
```

## Dependencies and Integration

### External Dependencies

| Dependency | Purpose |
|---|---|
| `javax.servlet` | Servlet API — the sole external import for both the listener and filter classes. |

There are no framework dependencies (Spring, Guice, CDI) declared in the codebase. The module is entirely self-contained within the Java EE servlet specification.

### Inbound Relationships

| Artifact | Role |
|---|---|
| `web.xml` | Declares `X33AppContextListener` as a `<listener>` and `X33JVRequestEncodingSjisFilter` as a `<filter>` with `<filter-mapping>` entries. |
| `web-full.xml` | Duplicate declarations for full-profile deployment environments (e.g., WildFly, WebLogic). |
| `com.fujitsu.futurity` (parent namespace) | The web package is a child of the top-level `com.fujitsu.futurity` namespace, which is expected to eventually contain the business logic and service layer that the web tier delegates to. |

### Outbound Relationships

No classes from `com.fujitsu` are imported by other packages in the codebase. This module is a leaf node — nothing depends on it, and it depends only on the servlet API. This isolation is both a safety net (low-risk to modify) and a signal (the module may be deprecated or still in planning).

## Module Interaction Map

```mermaid
flowchart LR
    subgraph CONTAINER["Servlet Container"]
        REQ["HTTP Request"]
    end

    subgraph WEB["com.fujitsu.futurity.web"]
        subgraph X33["x33 sub-package"]
            L["X33AppContextListener"]
            F["X33JVRequestEncodingSjisFilter"]
        end
    end

    subgraph DESC["Deployment Descriptors"]
        WD["web.xml / web-full.xml"]
    end

    WD -->|registers| L
    WD -->|registers| F
    REQ -->|lifecycle| L
    REQ -->|routing| F
    F -->|delegates| L
```

## Notes for Developers

- **Everything is currently a stub.** The listener has no class body, and the filter's `doFilter`, `init`, and `destroy` methods are no-ops. No runtime behavior depends on these components performing work.

- **Japanese encoding is an open risk.** If the Futurity application serves Japanese-language users, unhandled Shift JIS encoding will cause mojibake. To fix, `X33JVRequestEncodingSjisFilter.doFilter` should call `((HttpServletRequest) req).setCharacterEncoding("cp932")` before delegating. For correctness, wrap the request in a custom `HttpServletRequestWrapper` so `getParameter` calls throughout the application respect the encoding.

- **Listener implementation needs a design decision.** Before adding behavior to `X33AppContextListener`, determine whether it should implement `javax.servlet.ServletContextListener` (generic container lifecycle, receiving `contextInitialized`/`contextDestroyed`) or integrate with Spring by extending `ContextLoaderListener`. This choice dictates both the API to implement and the `web.xml` configuration required.

- **Thread-safety today is not a concern.** Both the filter and listener are stateless. Any future state added to these components should be handled carefully, especially application-scoped resources the listener may hold.

- **Low-risk area to modify.** Since no other package references classes from this module, changes here have no downstream impact. The module can be safely extended, refactored, or removed.

- **Possible deprecation.** Given that all components are empty stubs with no cross-module references, verify with the team whether the X33 / Futurity module is still in scope. If not, the `x33` package and its `web.xml` entries can be cleaned up to reduce deployment confusion.