# Com

## Overview

The `com` package is the top-level Java namespace root in this codebase. It serves as the container for all company-branded and third-party packages beneath the standard `com` domain. At present, the only documented area under `com` is the **Fujitsu** (`com.fujitsu`) branch, which houses a greenfield Japanese-language enterprise web application called **Futurity**.

Unlike mature areas of a codebase, the `com` package currently contains no indexed source files at its own level -- it functions purely as a package namespace. All substantive work lives in its child module, `com.fujitsu.futurity`, which is a Java EE servlet-based application scaffold targeting Japanese-language users. The application is in its earliest structural phase: the HTTP surface area has been defined and wired into the servlet container via XML deployment descriptors, but the business components behind that surface area are still stubs awaiting implementation.

## Sub-module Guide

### com.fujitsu -- Fujitsu-branded Area

The `com.fujitsu` namespace contains Fujitsu-related modules. Its sole documented child is **Futurity**.

#### com.fujitsu.futurity -- Futurity Application

**Package:** `com.fujitsu.futurity`

Futurity is a Japanese enterprise web application built on the Java EE servlet stack. It follows a web-first architecture: the HTTP-facing interface was designed and configured into the servlet container *before* downstream business logic was written. This scaffold-first approach means the application's external contract (encoding, lifecycle, deployment) was established as a foundation for future implementation work.

**Sub-packages:**

- **`com.fujitsu.futurity.web`** -- The web entry point for the entire application. This package defines the servlet-tier infrastructure that handles all HTTP interaction, including request routing, character encoding, and application lifecycle management. It is the outermost layer through which all client traffic enters the system.

- **`com.fujitsu.futurity.web.x33`** -- The first concrete feature area within the web tier. It contains two stubbed no-op components:
  - `X33JVRequestEncodingSjisFilter` -- An encoding filter intended to set Shift-JIS (CP932) character encoding on incoming requests.
  - `X33AppContextListener` -- A lifecycle listener for application-scoped resource initialization and cleanup.

**Relationship between packages:** The package hierarchy maps a clear layering model. `futurity` is the umbrella application; `web` is its HTTP-facing tier; `x33` is the first feature implemented within that tier. The deployment descriptor (`web-full.xml`) binds them together, declaring lifecycle ordering and request routing before any operational code exists.

## Key Patterns and Architecture

### Stub-First (Scaffold-First) Development

The dominant architectural decision throughout the `com` area is scaffold-first development. The components in `com.fujitsu.futurity.web.x33` are no-ops that exist solely to occupy their positions in the servlet container's lifecycle and filter chain. This signals a deliberate design process where integration points (character encoding, application-scoped resources) were identified during a design phase, and implementation followed only after the web-layer contract was established.

This pattern has important implications:
- Downstream teams can begin work on their components once the web contract is fixed, without waiting for full implementation.
- The absence of operational logic is intentional, not a gap or oversight.
- Once real implementations replace the stubs, the integration points are already wired and tested at the container level.

### Container-Managed Lifecycle

All components follow the Java EE servlet lifecycle model. The servlet container manages instantiation, lifecycle callbacks, and request dispatch. Components are singleton-scoped and shared across all requests, which imposes strict thread-safety discipline on any future implementation: any state added to these classes must be read-only after initialization or protected by synchronization.

### Deployment-Driven Configuration

Configuration is entirely externalized into `web-full.xml`, the canonical deployment descriptor. No annotations are used -- every filter mapping, listener registration, and servlet definition lives in XML. This approach:
- Keeps the code framework-agnostic and fully container-managed.
- Makes ordering and dependency inspection a configuration-level concern rather than a code-level one.
- Requires careful attention to the order of `<filter-mapping>` elements, since the container processes filters in declaration order.

### Request Encoding Strategy

The `X33JVRequestEncodingSjisFilter` is designed to intercept incoming requests and set the character encoding (Shift-JIS / CP932) before any downstream component reads request data. Because character encoding must be established before the request body is consumed, this filter's position in the chain is critical:

1. The HTTP request enters the web container.
2. The container invokes the `X33AppContextListener` at startup to initialize application-scoped resources.
3. On each request, the filter chain dispatches through `X33JVRequestEncodingSjisFilter` first, setting the encoding.
4. The request then passes through the downstream chain to whatever servlets or controllers handle the actual feature logic.

#### Module Architecture

```mermaid
flowchart TD
    SRC["com.fujitsu.futurity
Parent Package"] --> WEB["com.fujitsu.futurity.web
Web Entry Point"]
    WEB --> WEB_DESC["Servlet-tier infrastructure:
request handling, encoding,
lifecycle management"]
    WEB --> X33["com.fujitsu.futurity.web.x33
X33 Feature Web Layer"]
    X33 --> FILTER["X33JVRequestEncodingSjisFilter
Shift-JIS encoding filter (stub)"]
    X33 --> LISTENER["X33AppContextListener
Lifecycle listener (stub)"]
    WEB --> DESC["web-full.xml
Deployment Descriptor"]
    DESC --> WEB
    DESC --> X33
    SRC --> DESC
```

#### Request Lifecycle

```mermaid
flowchart LR
    CLIENT["HTTP Client"] --> |request| WC["Web Container"]
    WC --> |startup| LST["X33AppContextListener
.contextInitialized()"]
    LST --> |prepares| RES["X33 resources /
services in ServletContext"]
    WC --> |HTTP request| WEB["web-full.xml
filter mapping"]
    WEB --> |dispatches| FLT["X33JVRequestEncodingSjisFilter
.doFilter()"]
    FLT --> |passes through| CHN["downstream
filter chain"]
    WC --> |shutdown| LSH["X33AppContextListener
.contextDestroyed()"]
    LSH --> |releases| RES
```

## Dependencies and Integration

### External Dependencies

| Dependency | Purpose |
|------------|---------|
| `javax.servlet.Filter` | Implemented by the X33 encoding filter for request processing |
| `javax.servlet.ServletContextListener` (expected) | To be implemented by the X33 context listener for lifecycle management |
| `web-full.xml` | Deployment descriptor registering all web-layer components |

### Internal Dependencies

No inbound callers have been detected in the codebase index -- no other Java packages import or reference classes from `com.fujitsu.futurity` or its sub-packages. This confirms that the web module is newly introduced and operating in isolation. The filter is invoked purely through XML-based servlet container configuration rather than Java-level references from other packages.

### Integration Points (Planned)

When fully implemented, the web module will integrate through:

- **Filter chain:** The X33 filter delegates to the downstream chain, eventually reaching X33's servlets, controllers, or other web components (not yet present).
- **ServletContext:** The context listener will share application-scoped attributes and resources across components via the standard `ServletContext` mechanism.
- **Deployment descriptor:** All wiring flows through `web-full.xml`.

## Notes for Developers

1. **Both classes are stubs.** Neither the filter (`X33JVRequestEncodingSjisFilter`) nor the listener (`X33AppContextListener`) contains operational logic. This is an intentional scaffolded module awaiting implementation, not a bug.

2. **Implementing the filter:** When adding encoding logic, cast the `ServletRequest` to `HttpServletRequest`, call `setCharacterEncoding("SJIS")` (or `"CP932"`) before `chain.doFilter()`, and consider making the encoding configurable via a servlet init-param or context-param rather than hardcoding it.

3. **Implementing the listener:** Add `javax.servlet.ServletContextListener` as an implemented interface and provide `contextInitialized` and `contextDestroyed` methods. Coordinate with the X33 team on initialization ordering and resource lifecycle to avoid conflicts with other application components.

4. **Filter ordering is critical.** If the filter handles encoding, it must appear early in the `<filter-mapping>` order in `web-full.xml`, before any component that reads request parameters, form bodies, or JSON payloads.

5. **Thread safety.** As singleton container-managed components, both classes are instantiated once and handle all requests on shared instances. Any future state must be read-only after initialization, or protected by synchronization.

6. **No other module depends on this package.** Changes to these classes have limited blast radius within the existing codebase, since no other Java package imports or references them.

7. **Encoding choice matters for Japanese locales.** Verify whether the application requires Shift-JIS (`"SJIS"` / `"CP932"`) or has migrated to UTF-8. Modern applications typically use UTF-8, but legacy Japanese enterprise systems often require Shift-JIS for form data compatibility.

8. **This is a greenfield module.** The absence of indexed source files and classes at the `com` package level, and the stub nature of the source at the `com.fujitsu.futurity` level, suggests the source files are either not yet committed or are very small stubs. Developers working in this area should expect to build functionality from the scaffolding upward, using the deployment descriptor as the integration contract.