# Com

## Overview

The `com` namespace is a top-level Java package that groups two entirely distinct sub-packages with no code-level relationship to each other:

- **`com.example`** — A minimal collection of stub and regression-test fixtures used by build-time verification tooling. These classes are intentionally inert; they exist to exercise JSP import resolution and attribute ordering in the compiler or build pipeline, not to deliver application behavior.

- **`com.fujitsu`** — The packaging root for the **Futurity** suite, a family of Java EE web applications. Its primary child, `com.fujitsu.futurity`, hosts the **X33** variant — a Japan-focused application scaffold built around servlet filters and lifecycle listeners. The X33 components are currently deployed as no-op stubs: the structural hooks are in place, but the pipes are not yet carrying any signal.

Though both live under the `com` top-level namespace, these sub-packages operate in total isolation. There are no Java dependencies between them, no shared interfaces, and no cross-references. One is a test fixture (`com.example`); the other is an application skeleton (`com.fujitsu`).

## Sub-module Guide

### `com.example` — Test Fixtures

This namespace holds regression-test stubs. Its only documented child, **`bugca002`**, provides a single empty class (`KnownClass`) that serves as a resolvable import target for JSP view files in the `bug-ca-002-attr-order` test harness. The class exists solely so that JSP compilation and classpath resolution mechanisms have a stable symbol to reference — the code under test is the build tool, not the application logic.

### `com.fujitsu` — Futurity Application Suite

This namespace is the organizational root for the **Futurity** web application family. The module hierarchy narrows as follows:

| Level | Package | Role |
|-------|---------|------|
| Brand | `com.fujitsu` | Packaging root |
| Product | `com.fujitsu.futurity` | Application container (X33 Japan variant) |
| Tier | `com.fujitsu.futurity.web` | Web-tier layer |
| Variant | `com.fujitsu.futurity.web.x33` | Concrete application implementation |

Within the **x33** sub-module, two servlet-tier components are defined:

- **`X33JVRequestEncodingSjisFilter`** — Sets character encoding (MS932 / Shift JIS) on incoming HTTP requests. Targets Japanese language support.
- **`X33AppContextListener`** — Provides application-scoped startup and shutdown hooks.

Both components are no-op stubs. They implement their interfaces with empty bodies, suggesting early-stage scaffolding or a decommissioned application where the structural skeleton remains as a foundation for future work.

### How the sub-modules relate

The two sub-packages (`com.example` and `com.fujitsu`) are unrelated from a code perspective. Their only connection is that they share the `com` top-level namespace. Conceptually:

- `com.example` is **internal tooling** — its classes are consumed by the build/test pipeline to validate compiler and JSP resolution behavior.
- `com.fujitsu` is **application infrastructure** — its components are designed to be deployed as part of a Java EE web application, serving HTTP requests at runtime.

## Key Patterns and Architecture

```mermaid
flowchart TD
    PKG["com (root namespace)"] --> EXAM["com.example (test fixtures)"]
    PKG --> FUJI["com.fujitsu (Futurity app suite)"]
    EXAM --> BUG["bugca002 regression test"]
    BUG --> KC["KnownClass stub"]
    FUJI --> FUT["com.fujitsu.futurity"]
    FUT --> WEB["com.fujitsu.futurity.web"]
    WEB --> X33["x33 application variant"]
    X33 --> FL["X33JVRequestEncodingSjisFilter"]
    X33 --> LI["X33AppContextListener"]
```

### Stub-and-Reference Pattern

Used by `com.example`. Classes are deliberately sparse — empty fields, compiler-provided constructors, no-op methods. The intent is stability, not functionality. JSP views import these stubs to test the JSP compilation pipeline. This is a regression test pattern where the tool itself (the compiler/build system) is the code under test.

### Lifecycle-Request Separation

Used by `com.fujitsu.futurity.web.x33`. The X33 module cleanly separates application lifecycle concerns (`X33AppContextListener`, called once at deployment) from per-request concerns (`X33JVRequestEncodingSjisFilter`, called on every HTTP request). This is the standard Java EE servlet architecture pattern.

### Deployment Descriptor-Driven Wiring

Components in the X33 sub-module are explicitly declared in `web.xml` and `web-full.xml` rather than discovered via Servlet 3.0+ annotations. Both files register the same components, and any implementation changes must be reflected in both to avoid environment-specific behavior divergence.

### Skeleton Architecture

The `com.fujitsu` module is essentially a foundational framework — the plumbing has been built, but the pipes are not yet carrying any signal. Servlet filters, context listeners, and deployment descriptors are declared and wired, but their implementations are empty or no-op stubs. This pattern suggests either early-stage scaffolding built ahead of business logic, or a decommissioned application where the structural skeleton remains as a foundation for future reactivation.

## Dependencies and Integration

### `com.example` Dependencies

| Direction | Target | Description |
|-----------|--------|-------------|
| **Used by** | `BugCa002Language Before Import.jsp` | JSP view imports `KnownClass` to exercise JSP import resolution |
| **Consumes** | `java.lang` | Default Java runtime package (implicit for `KnownClass`) |

The `bugca002` module depends only on `java.lang`. No other internal or external packages are referenced.

### `com.fujitsu` Dependencies

All functionality within the Futurity/X33 components depends solely on the **Java Servlet API**:

| Dependency | Component | Purpose |
|---|---|---|
| `javax.servlet.Filter` | `X33JVRequestEncodingSjisFilter` | Servlet filter interface |
| `javax.servlet.ServletRequest` / `ServletResponse` | `X33JVRequestEncodingSjisFilter` | Request/response handling |
| `javax.servlet.FilterChain` | `X33JVRequestEncodingSjisFilter` | Filter chain delegation |
| `javax.servlet.FilterConfig` | `X33JVRequestEncodingSjisFilter` | Initialization parameters |
| `javax.servlet.ServletContextListener` | `X33AppContextListener` | Application lifecycle |
| `javax.servlet.ServletContextEvent` | `X33AppContextListener` | Lifecycle event payloads |

The code uses `javax.servlet` (Java EE / Servlet 3.x) package naming. It is advisable to confirm whether the build has migrated to `jakarta.servlet` (Jakarta EE / Servlet 5.x+), as this would require updating imports before any implementation work.

### Cross-module relationships

There are no cross-module dependencies between `com.example` and `com.fujitsu`, nor between any of their child sub-packages. Each operates in complete isolation.

## Notes for Developers

### Working with `com.example`

- **These are fixtures, not production code.** Classes in `com.example` are stubs by design. Do not assume missing fields, methods, or logic are oversights — they are intentional. If you need a non-trivial class for testing, create it in a new module rather than modifying an existing stub.
- **Check the test harness for context.** The `bugca002` naming convention and the `bug-ca-002-attr-order` directory strongly suggest this is tied to a specific regression test. If you are investigating why this code exists, look for the associated test definition in the test harness or issue tracker.
- **Package visibility matters.** Classes like `KnownClass` are declared `public` because they must be importable from JSP views in different packages.

### Working with `com.fujitsu`

- **Everything is a stub.** Neither the filter nor the listener contains executable logic. Adding implementation is safe — there is no existing behavior to break.
- **Character encoding is a priority area.** If the X33 application handles Japanese content, implementing `X33JVRequestEncodingSjisFilter` is likely one of the first practical tasks. A recommended approach is to check `req.getCharacterEncoding() == null` before setting the encoding, to avoid overriding an explicit client-specified `Content-Type` header.
- **Servlet API version matters.** The code references `javax.servlet` (Java EE / Servlet 3.x). Confirm whether the project has migrated to `jakarta.servlet` (Jakarta EE / Servlet 5.x+) before implementing any interface methods, as the package name will differ.
- **Coordinate across deployment profiles.** Changes to `web.xml` should be mirrored in `web-full.xml`. Divergence between these profiles is a common source of environment-specific bugs.
- **This appears to be a structural foundation.** The presence of properly named and deployed stubs suggests this package is intended to grow into a fully functional web tier. Treat these classes as extension points rather than dead code.
- **Indexing caveat.** Static analysis reports zero indexed classes and methods for the `com.fujitsu` root because the stub classes are minimal. Once implementation is added, the code index should be refreshed to capture new symbols.