# Com / Fujitsu / Futurity

## Overview

The `com.fujitsu.futurity` package is a top-level Java EE application module within the Fujitsu Futurity system. It appears to be a Japanese enterprise application that provides web-facing functionality, with the web layer serving as the primary integration point for external HTTP clients.

At the time of documentation, the module is in a greenfield -- early scaffolding stage. The only fully described sub-module is the web layer (`com.fujitsu.futurity.web`), which provides the container-managed entry point for HTTP request handling. Its contents are currently structural placeholders: filter and listener stubs registered in the deployment descriptor but not yet populated with operational logic. This pattern indicates a deliberate design approach where integration touchpoints are identified and wired into the servlet container before business logic is implemented.

The Futurity application targets Japanese-language users, as evidenced by the X33 filter's intent to handle Shift-JIS (SJIS/CP932) character encoding. This suggests the system operates within a legacy Japanese enterprise context where character set compatibility is a core requirement.

## Sub-module Guide

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

### com.fujitsu.futurity.web -- Web Layer Entry Point

**Package:** `com.fujitsu.futurity.web`

The web package is the application's HTTP surface area. It provides the servlet-tier infrastructure that bridges incoming web requests to internal services and business logic. The package follows standard Java EE conventions -- no framework-specific annotations are used; instead, components are wired through a deployment descriptor (`web-full.xml`) for container management.

Within the web package, the **X33 sub-module** (`com.fujitsu.futurity.web.x33`) represents the first concrete feature area. It defines two container-managed components:

- **`X33JVRequestEncodingSjisFilter`** -- A servlet filter for handling Shift-JIS character encoding on Japanese-language requests. Currently a no-op stub, it will sit early in the filter chain before any component reads request parameters.
- **`X33AppContextListener`** -- A planned application context listener for X33-specific initialization and cleanup during servlet container startup and shutdown. Currently a stub with no methods implemented.

These components operate at different lifecycle points (listener at startup/shutdown, filter at each request) but are coordinated through shared `ServletContext` state -- the standard Java EE pattern for cross-component communication without direct coupling.

## Key Patterns and Architecture

### Container-Managed Component Pattern

All web-layer components in Futurity follow the Java EE servlet lifecycle. The servlet container -- not an application framework -- manages instantiation, lifecycle callbacks, and dispatch. Components are instantiated once per deployment and reused across all requests and lifecycle events, requiring careful thread safety discipline.

### Stub-First / Scaffolded Development

Both classes in the X33 sub-module are currently no-ops. They exist as structural placeholders in `web-full.xml`, indicating that X33's web-layer touchpoints were identified during design and wired into the container before implementation began. This is a greenfield approach: define integration points and deployment configuration first, then fill in the operational logic.

### Filter Chain and Encoding Strategy

The X33 filter is designed to intercept incoming requests and set character encoding before downstream consumers read request data. Because encoding must be established before the request body is consumed, filter ordering in `web-full.xml` is a critical configuration concern. The filter must appear before any component that parses request parameters, form data, or JSON bodies.

### Deployment-Driven Configuration

The `web-full.xml` deployment descriptor is the canonical configuration point for all web-layer components. Both the filter and listener are registered through XML mapping rather than annotations, keeping the layer framework-agnostic and fully container-managed.

#### Module Architecture

```mermaid
flowchart TD
    SRC["com.fujitsu.futurity
Parent Package"] --> WEB["com.fujitsu.futurity.web
Web Entry Point"]
    WEB --> WEB_DESC["Servlet-tier infrastructure:
request handling, encoding,
lifecycle management"]
    WEB --> X33["com.fujitsu.futurity.web.x33
X33 Feature Web Layer"]
    X33 --> FILTER["X33JVRequestEncodingSjisFilter
Shift-JIS encoding filter (stub)"]
    X33 --> LISTENER["X33AppContextListener
Lifecycle listener (stub)"]
    WEB --> DESC["web-full.xml
Deployment Descriptor"]
    DESC --> WEB
    DESC --> X33
    SRC --> DESC
```

#### Request Lifecycle

```mermaid
flowchart LR
    CLIENT["HTTP Client"] -->|request| WC["Web Container"]
    WC -->|startup| LST["X33AppContextListener
.contextInitialized()"]
    LST -->|prepares| RES["X33 resources /
services in ServletContext"]
    WC -->|HTTP request| WEB["web-full.xml
filter mapping"]
    WEB -->|dispatches| FLT["X33JVRequestEncodingSjisFilter
.doFilter()"]
    FLT -->|passes through| CHN["downstream
filter chain"]
    WC -->|shutdown| LSH["X33AppContextListener
.contextDestroyed()"]
    LSH -->|releases| RES
```

## Dependencies and Integration

### External Dependencies

| Dependency | Purpose |
|------------|---------|
| `javax.servlet.Filter` | Implemented by the X33 encoding filter for request processing |
| `javax.servlet.ServletContextListener` (expected) | To be implemented by the X33 context listener for lifecycle management |
| `web-full.xml` | Deployment descriptor registering all web-layer components |

### Internal Dependencies

No inbound callers have been detected in the codebase index -- no other Java packages import or reference classes from `com.fujitsu.futurity.web` or its sub-packages. This confirms that the web module is either newly introduced or operating in isolation from other parts of the system. The filter is invoked purely through XML-based servlet container configuration rather than Java-level references.

### Integration with the Broader System

When fully implemented, the web module will integrate with the rest of the Futurity application through standard servlet mechanisms:

- **Filter chain:** The X33 filter delegates to the downstream chain, eventually reaching X33's servlets, controllers, or other web components (not yet present).
- **ServletContext:** The context listener will have access to the application's `ServletContext`, the standard mechanism for sharing application-scoped attributes and resources across components.
- **Deployment descriptor:** All components are wired through `web-full.xml`, the canonical configuration point for servlet container components.

## Notes for Developers

1. **Both classes are stubs.** Neither the filter nor the listener contains operational logic. This is a scaffolded module awaiting implementation -- not a bug.

2. **Implementing the filter:** When adding encoding logic, cast the `ServletRequest` to `HttpServletRequest`, call `setCharacterEncoding("SJIS")` (or `"CP932"`) before `chain.doFilter()`, and consider making the encoding configurable via a servlet init-param or context-param rather than hardcoding it.

3. **Implementing the listener:** Add `javax.servlet.ServletContextListener` as an implemented interface and provide `contextInitialized` and `contextDestroyed` methods. Coordinate with the X33 team on initialization ordering and resource lifecycle to avoid conflicts with other application components.

4. **Filter ordering is critical.** If the filter is used for encoding, it must appear early in the `<filter-mapping>` order in `web-full.xml`, before any component that reads request parameters.

5. **Thread safety.** As singleton container-managed components, both classes are instantiated once and handle all requests/lifecycle events on shared instances. Any future state must be read-only after initialization, or protected by synchronization.

6. **No other module depends on this package.** Changes to these classes have limited blast radius within the existing codebase, but any future X33 web components that reference the listener's initialization output will need to be considered.

7. **Encoding choice matters for Japanese locales.** If this filter is intended to handle Japanese input, verify whether the application requires Shift-JIS (`"SJIS"` / `"CP932"`) or has migrated to UTF-8. Modern applications typically use UTF-8, but legacy Japanese enterprise systems often require Shift-JIS for form data compatibility.

8. **This is a greenfield module.** The absence of indexed source files and classes in the module index suggests the source files are either not yet committed or are very small stubs. Developers working in this area should expect to build functionality from the scaffolding upward.