# Com

## Overview

The `com` package is the top-level Java package namespace in this codebase, rooted under the standard `com` top-level domain prefix. It serves as the parent container for one or more vendor- or organization-scoped sub-packages. Within the current index, the only documented child is `com.fujitsu`, which groups Fujitsu's Java EE web applications.

The `com` package itself contains no source files, classes, or methods at this indexing level. Its role is purely organizational — it provides the structural umbrella under which more specific namespaces (like `com.fujitsu`) reside. The actual application logic, data models, and service implementations are all one or more levels deeper in the hierarchy.

This top-level package reflects a common convention in Java projects where the `com` prefix signals a commercial organization, with subsequent segments narrowing down to a specific company, product, or subsystem.

## Sub-module Guide

### `fujitsu` — Fujitsu Application Namespace

The `com.fujitsu` sub-package is the primary (and currently only documented) child under `com`. It acts as the root namespace for Fujitsu-related Java EE applications, currently hosting the **Futurity** web application.

**What `fujitsu` contributes to the `com` hierarchy:**

- It provides the organizational boundary that groups all Fujitsu application code — filters, servlets, listeners — under a shared root prefix.
- Its sole concrete application (`futurity`) implements a browser-based multi-market interface with locale-specific variants (notably a Japanese X33 variant with Shift-JIS encoding).
- While `fujitsu` itself contains no indexed classes at this level, it delegates real responsibility to its sub-packages (`futurity` → `web` → `x33`), which house the actual request-processing infrastructure.

**Relationship between children:** Currently there is only one child under `com` (`fujitsu`), so no inter-child relationships exist in the index. However, the structure anticipates future expansion — for example, additional locale variants or Fujitsu product lines could introduce sibling packages under `com.fujitsu` alongside `futurity`.

## Key Patterns and Architecture

### Package Hierarchy

```mermaid
flowchart TD
    Com["com (top-level namespace)"] --> Fujitsu["com.fujitsu<br/>Fujitsu application root"]
    Fujitsu --> Futurity["com.fujitsu.futurity<br/>Futurity web app"]
    Futurity --> X33["com.fujitsu.futurity.x33<br/>Japanese locale variant"]
```

### Request Processing Pipeline

Browser requests enter the system through the Fujitsu Futurity application's servlet filter chain, which normalizes encoding and locale before dispatching into business logic:

```mermaid
sequenceDiagram
    participant Browser as "Browser"
    participant Container as "Servlet Container"
    participant Filter as "X33 Filter"
    participant Chain as "FilterChain"
    participant Servlet as "Target Servlet"
    Browser->>Container: HTTP request
    Container->>Filter: doFilter
    Filter->>Chain: chain.doFilter
    Chain->>Servlet: deliver request
    Servlet-->>Filter: return response
    Filter-->>Browser: respond to client
```

### Architectural Layering

```mermaid
flowchart TD
    Client["Browser / Client"] --> Dispatcher["Servlet Dispatcher"]
    Dispatcher --> X33Filter["X33 Filter"]
    X33Filter --> TargetServlet["Target Servlet"]
    TargetServlet --> Business["Business Logic"]
    Business --> Service["Service Layer"]
```

The outermost layer (`com`) is purely organizational. The first functional layer (`com.fujitsu.futurity`) sits at the HTTP boundary, enforcing encoding and locale constraints before data reaches the application's core processing pipeline. Each subsequent layer handles progressively higher-abstraction concerns.

### Design Patterns

- **Filter Chain Pattern**: Requests are normalized through `javax.servlet.Filter` implementations (e.g., `X33JVRequestEncodingSjisFilter`) before reaching target servlets. This is the standard Java EE approach for cross-cutting concerns like encoding normalization.
- **Scaffolded Architecture**: Many components are scaffolded — class structures and interfaces are correctly defined, but implementation bodies are deferred or no-op. This is typical during localization work where the framework is set up before locale-specific logic is fully specified.
- **Locale-Specific Variants**: The X33 subpackage demonstrates a strategy pattern for market-specific configuration, where encoding, formatting, and lifecycle behavior are specialized per locale.

## Dependencies and Integration

### Outbound Dependencies

| Dependency | Role |
|---|---|
| `javax.servlet.*` | Standard Java EE Servlet API — filter interface, request/response types, and listener interfaces used by the Futurity web application's X33 filter and context listener. |
| Deployment descriptor (`web-full.xml`) | Registers the X33 servlet filter with the servlet container, defining URL patterns and initialization parameters. |

### Cross-module Relationships

The `com` package has no direct outbound code dependencies — it is a namespace, not a source container. Its child `com.fujitsu` depends on the standard Java EE servlet API and connects to downstream business logic and data access layers that reside in packages outside the current index.

Within the `com.fujitsu` subtree, the `futurity` web application sits at the HTTP boundary. Sibling locale packages (e.g., an English-language variant) may coexist alongside the X33 Japanese variant, each with its own encoding and lifecycle configuration. The X33 filter delegates to downstream servlets and controllers for actual business logic processing.

## Notes for Developers

- **`com` is purely organizational**: No source files, classes, or methods are indexed under this package. All actual code lives in downstream subpackages, starting with `com.fujitsu`.
- **Scaffolding vs. production**: Components in `com.fujitsu.futurity` are often scaffolded — their class structures and interfaces are correct, but implementation bodies may be deferred or no-op. For example, `X33JVRequestEncodingSjisFilter` currently forwards all requests unmodified. Always verify whether the scaffold represents the intended final structure or if implementation is still pending.
- **Localization focus**: The X33 variant is a Japanese-market locale with Shift-JIS encoding support. When working on other market variants, look for related encoding filters or locale configurations in sibling packages.
- **No data model at this level**: The `com` hierarchy contains no data model classes, DTOs, or entity types. It is purely a request-processing and lifecycle infrastructure layer. Business logic and data access reside in downstream packages not captured in this index.
- **Extensibility points**:
  - The X33 filter's `init()` method is the natural place to read encoding parameters from `FilterConfig`.
  - The `X33AppContextListener` (once fully implemented) would be the natural place to initialize locale-specific resources at application startup, such as registering locale-aware `NumberFormat` or `DateFormat` instances.
- **Future expansion**: Additional Fujitsu product lines or locale variants could introduce new packages under `com.fujitsu`, and other organizations could appear as sibling namespaces under `com`.