# Com / Fujitsu

## Overview

The `com.fujitsu` package is a Java EE web application area belonging to the Fujitsu Futurity product line. It represents the web-facing boundary of the application — the registration layer through which all HTTP requests and application lifecycle events enter from the JEE servlet container into the domain logic of downstream packages.

Today, this area is best understood as a **structural skeleton** rather than an active processing layer. It defines the scaffolding for web-tier components (servlet filters, context listeners) that are wired into the container exclusively through XML deployment descriptors (`web.xml` and `web-full.xml`). The components themselves are currently no-op stubs, meaning the infrastructure is in place but the actual business logic — request handling, character encoding, initialization — resides in or awaits implementation in downstream modules.

This appears to be a legacy Java EE application, likely targeting Japanese enterprise deployments given the presence of Shift JIS encoding scaffolding. The codebase follows a **configuration-over-code** pattern and a **stub-first, implement-later** approach, suggesting this area is in a transitional or legacy state — perhaps a greenfield scaffolding effort, a legacy codebase awaiting feature migration, or an integration layer where the primary business logic lives in sibling packages.

## Sub-module Guide

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

### Futurity — `com.fujitsu.futurity`

The `com.fujitsu.futurity` package is the web application that forms the core of this module. It is the structural skeleton of the Futurity application's web tier, providing the servlet-container boundary. Its sole documented sub-system is:

- **Web** (`com.fujitsu.futurity.web`) — The web-tier root, which organizes HTTP-facing components into sub-systems. Each sub-system exposes a standard pair of servlet lifecycle hooks: a **filter** for per-request processing and a **listener** for application-wide initialization and teardown.
- **X33** (`com.fujitsu.futurity.web.x33`) — A sub-system within the web tier that provides two components:
  - **X33JVRequestEncodingSjisFilter** — A servlet filter designed to set incoming HTTP request encoding to Shift JIS (Windows-31J) for Japanese-language input. Currently a pure pass-through that calls `chain.doFilter(req, res)` without inspecting or modifying the request.
  - **X33AppContextListener** — A servlet context listener registered for application startup and shutdown events. Currently the class body is entirely empty, so the container instantiates it but performs no action.

**How they relate:** The X33 filter and listener serve complementary but distinct roles. The filter handles per-request concerns (encoding) while the listener handles application-wide concerns (initialization, teardown). Together they form a complete but inert pair of hooks — the infrastructure is registered in `web.xml` and `web-full.xml`, ready for X33-specific logic to be grafted in without deployment changes. Neither component has Java-level dependencies on other classes within the `com.fujitsu.futurity` codebase; their integration with the rest of the system is implicit, through the servlet container's request and lifecycle wiring.

## Key Patterns and Architecture

### Configuration-over-Code Registration

All components in this module are wired into the servlet container exclusively through `web.xml` and `web-full.xml` deployment descriptors. No programmatic `@WebFilter` or `@WebListener` annotations are used. This approach is typical of legacy Java EE applications that predate servlet 3.0 annotations, or of enterprise deployments that prefer explicit, auditable, version-controlled XML configuration.

### No-Op Stub Pattern

The codebase follows a **stub-first, implement-later** approach. Rather than omitting component registration entirely (which would require editing deployment descriptors each time), placeholder classes are registered upfront and implemented incrementally. This pattern minimizes merge conflicts and deployment risk when adding new web-layer functionality, and strongly suggests this area of the codebase is in a transitional or legacy state.

### Request and Lifecycle Flow

The following diagram illustrates how the X33 components fit into the overall web request and application lifecycle within the Futurity web tier:

```mermaid
flowchart TD
    subgraph F["com.fujitsu - Fujitsu Package"]
        subgraph Fut["com.fujitsu.futurity - Futurity Application"]
            subgraph Web["com.fujitsu.futurity.web - Web Tier Root"]
                subgraph X33["com.fujitsu.futurity.web.x33"]
                    X33F["X33JVRequestEncodingSjisFilter<br/>Per-request SJIS encoding"]
                    X33L["X33AppContextListener<br/>App lifecycle hooks"]
                end
            end
        end
    end

    webxml["web.xml / web-full.xml"] --> X33F
    webxml --> X33L

    X33F --> chain["chain.doFilter(req, res)"]
    chain --> target["Downstream servlet / controller"]

    X33L --> init["contextInitialized()"]
    init --> services["Downstream service init"]

    note["All components are currently no-op stubs"]
```

### Encoding Strategy (Planned)

The filter name (`X33JVRequestEncodingSjisFilter`) implies an intended encoding strategy: set the request character encoding to **Windows-31J** (the MIME-compatible alias for Shift JIS) before the request is processed. This is the standard approach in legacy Japanese enterprise applications where forms and API payloads use SJIS rather than UTF-8. The intended implementation would look like:

```java
((HttpServletRequest) req).setCharacterEncoding("Windows-31J");
chain.doFilter(req, res);
```

Until this is implemented, the filter is transparent and offers no encoding guarantees.

## Dependencies and Integration

### External Dependencies

Both the X33 filter and listener depend solely on the standard Java EE / Jakarta EE Servlet API. No other packages within `com.fujitsu.futurity` are imported.

| Dependency | Purpose |
|---|---|
| `javax.servlet.Filter` API | Provides the `Filter` interface and `FilterChain` |
| `javax.servlet.ServletRequest` / `ServletResponse` | Request and response types passed through the filter |
| `javax.servlet.FilterConfig` / `FilterChain` | Container-provided configuration and chain management |

### Integration with the Rest of the System

The web package is a **leaf layer** — it has no child packages of its own and delegates all request handling to downstream modules. The X33 components act as a leaf module with no outgoing Java-level dependencies; their integration point with the rest of the Futurity system is implicit:

- **Request flow:** Incoming HTTP requests matching the X33 URL pattern flow through the filter chain, then land in X33-targeting servlets, controllers, or action classes in sibling packages.
- **Lifecycle flow:** If the listener is implemented with `ServletContextListener`, it would initialize services or resources consumed by downstream components during application startup, and perform cleanup on shutdown.

### Deployment Descriptor Wiring

Both components are registered in two descriptors:

| Descriptor | Role |
|---|---|
| `web.xml` | Primary deployment descriptor; registers filter and listener |
| `web-full.xml` | Extended/alternate deployment descriptor; mirrors registration for specific deployment profiles |

Changes to one descriptor may need to be mirrored in the other depending on your deployment profile.

## Notes for Developers

- **All components are no-ops.** If you are onboarding to the X33 web layer, be aware that the filter does not perform encoding and the listener does not run any initialization code. Functionality must be added explicitly.
- **The filter needs encoding logic.** To activate Shift JIS encoding, add `((HttpServletRequest) req).setCharacterEncoding("Windows-31J")` in `doFilter()` before `chain.doFilter(req, res)`. Consider making this conditional on the request path if only Japanese endpoints need SJIS encoding.
- **The listener needs interface implementation.** To make the listener functional, add `implements javax.servlet.ServletContextListener` and implement `contextInitialized` and optionally `contextDestroyed`.
- **Thread safety is not a concern** for the current no-op implementations, but any future initialization logic in the listener must account for the fact that `contextInitialized` runs on the container's startup thread — heavy blocking work will delay application startup.
- **Both components are registered in two descriptors.** Changes to one (`web.xml`) may need to be mirrored in the other (`web-full.xml`) depending on your deployment profile. Check your CI/CD pipeline to understand when each is used.
- **This is a structural skeleton.** The web tier currently does not implement request-handling logic itself; it registers lifecycle hooks that downstream modules use. When adding new web-layer functionality, look to sibling packages for the actual controllers and dispatchers.