# Com / Fujitsu / Futurity

## Overview

The `com.fujitsu.futurity` package sits at the web entry point of the Fujitsu Futurity platform. It provides the **infrastructure scaffolding** between the servlet container and the application's business logic — the thin boundary where HTTP traffic first arrives and lifecycle events (startup, shutdown) are dispatched.

This module does not contain business logic. Instead, it establishes a **stable deployment contract** through servlet listeners, filters, and XML deployment descriptors. Its purpose is so that the business layers below can evolve without requiring changes to how requests enter the system. The package follows an extension-point pattern: components are declared, registered, and intentionally left as no-ops today so that future logic can be absorbed without reworking deployment descriptors.

The most significant child of this web package is the **X33** sub-module, a Japanese-market deployment profile that handles Shift-JIS character encoding and provides lifecycle hooks for X33-specific features.

## Sub-module Guide

### `web` — The Web-Layer Foundation

The `web` package is the sole child of `com.fujitsu.futurity` and serves as the HTTP entry point for the Futurity platform. It contains:

- **`web.x33`** — The X33 sub-module (detailed below), the only child of this package.

The web package itself does not define sub-packages beyond X33. Its entire role is to wire together listeners and filters that sit in the servlet pipeline. There is no Spring wiring, no framework-driven configuration, and no imports beyond the Servlet API. This isolation is by design: the web layer defines a contract through XML and calls into nothing else at compile time.

### `web.x33` — Japanese-Market Deployment Subsystem

X33 is the only implemented (though currently no-op) child of the web package. It represents a specialized deployment profile for the Japanese market, as indicated by the `JV` (Japan) prefix in class names and the Shift-JIS encoding focus.

X33 splits across two components at different lifecycle points:

- **`web.x33.listener`** — Provides `X33AppContextListener`, a servlet context listener stub that fires once at application startup. It is intended to initialize X33-specific resources, load configuration, and populate `ServletContext` attributes.

- **`web.x33.filter`** — Provides `X33JVRequestEncodingSjisFilter`, a servlet filter stub that fires on every incoming HTTP request before the request reaches the target servlet. It was designed to set Shift-JIS request encoding for Japanese-language requests.

**How they relate:** The listener and filter operate at different points in the application lifecycle but share a common scope through `ServletContext`. The listener (setup phase) is intended to configure shared state that the filter (per-request processing phase) could consume — for example, the listener might load encoding configuration, and the filter might read it at request time. In their current stub state, there is no runtime interaction, but the architectural intent is a clean **setup vs. processing** separation. Both components are registered exclusively through XML deployment descriptors, making them portable across deployment profiles.

### Other Children

No additional child sub-packages are currently defined under `com.fujitsu.futurity`. The `web` package (and within it, X33) is the sole documented extension point.

## Key Patterns and Architecture

### Extension-Point Pattern (Scaffolding)

Every class in this module follows the same pattern: declare a descriptively named class in the correct package, register it in `web.xml`, and leave the implementation empty. This is intentional. These are **extension points** designed to absorb future logic without requiring deployment descriptor rework.

This pattern yields three benefits:

1. **Migration safety** — The deployment contract is preserved even if the actual implementation is ported from a legacy system or migrated to a different package.
2. **Deployment-first** — The container knows about these components before they have behavior, so removing them requires coordinated changes to both `web.xml` and `web-full.xml`.
3. **Low coupling** — The stubs have no imports beyond the servlet API, meaning they can be implemented in isolation.

### Dual-Descriptor Deployment

The X33 filter is declared in both `web.xml` and `web-full.xml`. This dual-declaration pattern suggests **conditional deployment profiles** — perhaps 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 filter's name (`X33JVRequestEncodingSjisFilter`) signals that character encoding is treated as a cross-cutting concern — something that must be applied to all requests before they reach the business layer. This is a common pattern in Java EE applications targeting markets with non-ASCII character sets. The Shift-JIS specificity suggests backward compatibility with legacy Japanese clients or back-end systems, even though modern deployments could migrate to UTF-8.

### 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.

## Dependencies and Integration

### External Dependencies

The web 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 web 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 web 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).