# Com / Fujitsu

## Overview

The `com.fujitsu` package represents the Fujitsu-specific Java EE integration layer for the Futurity platform. It serves as the web-entry-point boundary where HTTP traffic first arrives from the servlet container before being routed into application business logic.

This package is primarily an **infrastructure scaffolding** — it defines the deployment contract (listeners, filters, and XML descriptors) rather than containing business logic itself. The design philosophy here is extension-first: stub classes are declared in the correct packages and registered in deployment descriptors, leaving implementations as no-ops so that future logic can be absorbed without reworking the container configuration. This makes the module a stable, low-coupling boundary that isolates the servlet container lifecycle from the application's internal architecture.

The package has no indexed source files or classes in the current code analysis. This may reflect incomplete source indexing or a stub-only codebase. Despite this, the documented structure reveals a deliberate architecture worth understanding, as described below.

## Sub-module Guide

### `futurity` — The Futurity Platform Web Layer

The `futurity` sub-module (documented in its own wiki page) is the primary — and currently sole — content within `com.fujitsu`. It provides the web-layer foundation for the Futurity platform, focusing on three areas:

- **Lifecycle management** via servlet context listeners (`X33AppContextListener`) that fire at application startup.
- **Request interception** via servlet filters (`X33JVRequestEncodingSjisFilter`) that sit in the HTTP pipeline before requests reach target servlets.
- **Deployment configuration** through XML descriptors (`web.xml`, `web-full.xml`) that declare all components.

The X33 component within `futurity` is a specialized deployment profile for the Japanese market, handling Shift-JIS character encoding. It splits across a **setup phase** (the listener, which configures shared `ServletContext` state at startup) and a **processing phase** (the filter, which handles per-request encoding). These two components share the `ServletContext` scope, creating a clean separation between one-time initialization and repeated request processing.

**Relationship between X33 components:** The listener and filter represent a classic setup-vs-processing split. The listener prepares shared state; the filter consumes it. While they are no-ops in their current stub state, the architectural intent is that the listener populates context attributes (such as encoding configuration) that the filter reads at request time. This decoupling means either component can be implemented, modified, or replaced independently.

No other child packages are currently documented under `com.fujitsu.futurity` beyond the `web` package and its `x33` sub-module. The package is designed to grow through additional extension points declared in the same pattern: class in the right package, entry in the XML, empty implementation.

## Key Patterns and Architecture

### Extension-Point Pattern (Scaffolding)

Every class across the `com.fujitsu` package hierarchy follows the same extension-point pattern. A class is declared with a descriptive name in the appropriate package, registered in the deployment descriptor, and left as an empty stub. This pattern yields three benefits:

1. **Migration safety** — the deployment contract is preserved even if implementations change or move packages.
2. **Deployment-first** — the container knows about components before they have behavior, so removal requires coordinated descriptor changes.
3. **Low coupling** — stubs have no imports beyond the Servlet API, allowing isolated implementation.

### Dual-Descriptor Deployment

The X33 filter is declared in both `web.xml` and `web-full.xml`, suggesting conditional deployment profiles — a "full" WAR that includes all X33 features and a "lite" WAR that omits them. Any change to X33 registration must be reflected in both descriptors to avoid environment-specific failures.

### Character Encoding as a Cross-Cutting Concern

The Shift-JIS encoding filter treats character encoding as a cross-cutting concern, applied to all requests before they reach the business layer. This is common in Java EE applications targeting markets with non-ASCII character sets and reflects backward compatibility requirements with legacy Japanese clients or back-end systems.

### Data Flow

```mermaid
flowchart TD
    subgraph Startup["Application Startup"]
        WebXml1["web.xml (listener registration)"] -->|instantiates| Listener["X33AppContextListener"]
        Listener -->|populates| AppCtx["ServletContext (X33 shared state)"]
    end
    subgraph Pipeline["Request Processing Pipeline"]
        Incoming["Incoming HTTP Request"] -->|enters chain| Filter["X33JVRequestEncodingSjisFilter"]
        Filter -->|passes through| Next["Next Filter / Target Servlet"]
        Next -->|returns| Response["HTTP Response"]
    end
    WebXml2["web.xml / web-full.xml (filter mapping)"] -->|wired to URL patterns| Filter
    AppCtx -.->|context scope connects| Pipeline
```

The diagram shows how the listener operates at the top level (once, at startup) while the filter operates at the request level (repeatedly, per-request), with `ServletContext` acting as the shared scope that connects them.

### Component Relationship

```mermaid
flowchart LR
    subgraph com_fujitsu["com.fujitsu"]
        subgraph futurity["com.fujitsu.futurity"]
            subgraph web["com.fujitsu.futurity.web"]
                Listener["X33AppContextListener"]
                Filter["X33JVRequestEncodingSjisFilter"]
            end
        end
    end
    WebXml["web.xml / web-full.xml"] -->|registers| Listener
    WebXml -->|maps| Filter
    Listener -->|shares| AppCtx["ServletContext"]
    AppCtx -.->|scope| Filter
```

This relationship diagram shows how the deployment descriptors wire the listener and filter into the servlet container, and how `ServletContext` provides the shared scope between them.

## Dependencies and Integration

### External Dependencies

The `com.fujitsu` package depends solely on the Java Servlet API:

| Dependency | Used By | Purpose |
|---|---|---|
| `javax.servlet.ServletContextListener` | `X33AppContextListener` | Lifecycle event handling |
| `javax.servlet.Filter` | `X33JVRequestEncodingSjisFilter` | Request/response interception |
| `javax.servlet.FilterConfig` | `X33JVRequestEncodingSjisFilter` | Initialization configuration |
| `javax.servlet.FilterChain` | `X33JVRequestEncodingSjisFilter` | Chain delegation |
| `javax.servlet.ServletRequest` | `X33JVRequestEncodingSjisFilter` | Incoming request access |
| `javax.servlet.ServletResponse` | `X33JVRequestEncodingSjisFilter` | Outgoing response access |

No application-level classes are imported. There is no Spring, Guice, or other framework wiring. This minimal dependency footprint makes the module highly portable and easy to reason about.

### Integration with the Rest of the System

The `com.fujitsu` package acts as a **pure entry point**. It does not call into any other module and has no declared package dependencies. Integration happens indirectly:

- The **listener** can populate `ServletContext` attributes that downstream components (e.g., Spring beans, other filters) can read at startup.
- The **filter** sits in the servlet chain, meaning it processes every request before it reaches controllers, services, or any other subsystem. Once implemented, it could modify request parameters, set headers, or validate encoding before forwarding.

Because both components are no-ops today, there is no runtime impact on the rest of the system. They are hooks waiting for content.

### Cross-Module Relationships

No cross-module dependencies were detected in the code index. The `com.fujitsu` package is architecturally an **isolated boundary** — it defines the contract through XML but does not pull in other modules at compile time. This is by design: the web layer should be decoupled from business logic so that it can be tested, deployed, and replaced independently.

## Notes for Developers

- **Everything is a stub.** The classes `X33AppContextListener` and `X33JVRequestEncodingSjisFilter` are scaffolding with no runtime behavior. If you are tasked with implementing X33 initialization or encoding logic, these are your entry points. No existing behavior to preserve or break.

- **The listener may not implement the interface.** `X33AppContextListener` should implement `ServletContextListener` with `contextInitialized()` and `contextDestroyed()` methods. Verify this before adding lifecycle logic — if the interface declaration is missing, the servlet container will not invoke your code.

- **The filter does not set encoding.** If Shift-JIS handling is still required, the encoding must be set manually in `doFilter()` before `chain.doFilter()`. For example: `((HttpServletRequest) req).setCharacterEncoding("SJIS")`. If the system is modernizing away from Shift-JIS, consider whether UTF-8 is viable instead, which would eliminate the need for this filter entirely.

- **Always update both descriptors.** Changes to listener or filter registration must be reflected in both `web.xml` and `web-full.xml`. Failure to do so may cause environment-specific failures (working in one profile but not the other).

- **Use XML, not annotations.** To maintain consistency, new listeners and filters for this module should also be declared in the XML deployment descriptors rather than using `@WebListener` or `@WebFilter` annotations.

- **The X33 module targets the Japanese market.** The naming (`JV`, `Sjis`) and encoding focus indicate this is a Japan-specific deployment profile. If you are working on localization or character encoding, be aware of the Shift-JIS legacy and the potential opportunity to migrate to UTF-8.

- **No source files are indexed.** Static analysis tools may not currently recognize the source files for this package. Ensure the source path is included in the analysis configuration if you rely on tooling for this module.

- **No runtime interaction yet.** While the listener and filter share `ServletContext` as a potential bridge, they do not currently communicate. If you connect them, document the contract (e.g., what context attributes the listener sets and what the filter reads).

## Summary

The `com.fujitsu` package is the Fujitsu platform's servlet-level integration layer. It is intentionally lightweight — a set of extension points declared through Java classes and XML descriptors, waiting for implementation. The X33 sub-module within it handles Japanese-market concerns (primarily Shift-JIS encoding) through a listener/filter pair that follows a clean setup-vs-processing separation. The entire module depends only on the Servlet API and is architecturally isolated from the rest of the system, serving as a stable deployment contract for HTTP traffic entry.