# WIA-EDU-019 Digital Content Standard v1.2
## Phase 3: Distribution Protocol & Content Delivery
**Status:** ✅ Complete
**Version:** 1.2.0
**Date:** 2025-01-15
**Philosophy:** 弘益人間 (Benefit All Humanity)
---
## 1. Overview
Phase 3 defines the protocols and mechanisms for distributing WIA-compliant digital content efficiently, securely, and globally. This specification ensures optimal content delivery, offline support, and synchronization across devices.
## 2. Scope
Phase 2 covers:
- Content Delivery Network (CDN) integration
- Adaptive streaming protocols
- Progressive download and caching
- Offline-first architecture
- Synchronization mechanisms
- Security and encryption
## 3. Content Delivery Networks
### 3.1 CDN Requirements
All content SHOULD be distributed via CDN with:
- Global edge server distribution
- HTTPS/TLS 1.3 encryption
- HTTP/2 or HTTP/3 support
- Intelligent caching strategies
- DDoS protection
- Geographic load balancing
### 3.2 CDN Configuration
```json
{
"cdn": {
"provider": "cloudflare",
"distribution": "global",
"origins": [
{
"url": "https://origin.example.com",
"protocol": "https",
"port": 443
}
],
"caching": {
"defaultTTL": 86400,
"maxTTL": 31536000,
"minTTL": 0
},
"compression": {
"gzip": true,
"brotli": true
},
"edgeLocations": [
"us-east", "us-west", "eu-west",
"asia-northeast", "asia-southeast"
]
}
}
```
## 4. Adaptive Streaming
### 4.1 HLS (HTTP Live Streaming)
**Master Playlist (playlist.m3u8):**
```m3u8
#EXTM3U
#EXT-X-VERSION:6
#EXT-X-STREAM-INF:BANDWIDTH=800000,RESOLUTION=640x360
360p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=1400000,RESOLUTION=842x480
480p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=2800000,RESOLUTION=1280x720
720p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=5000000,RESOLUTION=1920x1080
1080p.m3u8
#EXT-X-STREAM-INF:BANDWIDTH=8000000,RESOLUTION=3840x2160
4k.m3u8
```
**Media Playlist (1080p.m3u8):**
```m3u8
#EXTM3U
#EXT-X-VERSION:6
#EXT-X-TARGETDURATION:10
#EXT-X-MEDIA-SEQUENCE:0
#EXTINF:10.0,
segment-00.ts
#EXTINF:10.0,
segment-01.ts
#EXTINF:10.0,
segment-02.ts
#EXT-X-ENDLIST
```
### 4.2 DASH (MPEG-DASH)
**MPD Manifest:**
```xml
1080p/
720p/
```
## 5. Progressive Download
### 5.1 Byte-Range Requests
Support HTTP range requests for partial content delivery:
```http
GET /video.mp4 HTTP/1.1
Host: cdn.example.com
Range: bytes=0-1048575
```
**Response:**
```http
HTTP/1.1 206 Partial Content
Content-Range: bytes 0-1048575/245760000
Content-Length: 1048576
Content-Type: video/mp4
[Binary data]
```
### 5.2 Content Chunking
Large files SHOULD be split into manageable chunks:
- Chunk size: 1-5 MB
- Support resumable downloads
- Verify integrity with checksums
## 6. Caching Strategies
### 6.1 Cache-Control Headers
```http
# Static assets (long-lived)
Cache-Control: public, max-age=31536000, immutable
# Dynamic content (short-lived)
Cache-Control: public, max-age=3600, must-revalidate
# Private content
Cache-Control: private, max-age=0, no-cache
```
### 6.2 Service Workers for Client-Side Caching
```javascript
// service-worker.js
const CACHE_NAME = 'wia-content-v1';
const urlsToCache = [
'/',
'/styles/main.css',
'/scripts/app.js',
'/data/manifest.json'
];
self.addEventListener('install', (event) => {
event.waitUntil(
caches.open(CACHE_NAME)
.then((cache) => cache.addAll(urlsToCache))
);
});
self.addEventListener('fetch', (event) => {
event.respondWith(
caches.match(event.request)
.then((response) => {
// Cache hit - return response
if (response) {
return response;
}
// Clone request for fetch
const fetchRequest = event.request.clone();
return fetch(fetchRequest).then((response) => {
// Check if valid response
if (!response || response.status !== 200 || response.type !== 'basic') {
return response;
}
// Clone response for cache
const responseToCache = response.clone();
caches.open(CACHE_NAME)
.then((cache) => {
cache.put(event.request, responseToCache);
});
return response;
});
})
);
});
```
## 7. Offline Support
### 7.1 Offline-First Architecture
```javascript
// Offline detection
window.addEventListener('online', () => {
console.log('Online - syncing content');
syncContent();
});
window.addEventListener('offline', () => {
console.log('Offline - using cached content');
loadCachedContent();
});
// Check connection status
if (navigator.onLine) {
fetchLatestContent();
} else {
loadCachedContent();
}
```
### 7.2 IndexedDB for Offline Storage
```javascript
// Open database
const request = indexedDB.open('WIAContent', 1);
request.onupgradeneeded = (event) => {
const db = event.target.result;
const objectStore = db.createObjectStore('content', { keyPath: 'id' });
objectStore.createIndex('type', 'type', { unique: false });
objectStore.createIndex('language', 'language', { unique: false });
};
// Store content
function storeContent(content) {
const transaction = db.transaction(['content'], 'readwrite');
const objectStore = transaction.objectStore('content');
objectStore.add(content);
}
// Retrieve content
function getContent(id) {
return new Promise((resolve, reject) => {
const transaction = db.transaction(['content']);
const objectStore = transaction.objectStore('content');
const request = objectStore.get(id);
request.onsuccess = () => resolve(request.result);
request.onerror = () => reject(request.error);
});
}
```
## 8. Synchronization
### 8.1 Content Sync Protocol
```http
POST /sync
Authorization: Bearer {access_token}
Content-Type: application/json
{
"deviceId": "device-123",
"lastSyncTimestamp": "2025-01-20T10:00:00Z",
"localContent": [
{
"id": "content-123",
"version": "1.0.0",
"checksum": "abc123..."
}
]
}
```
**Response:**
```json
{
"syncId": "sync-456",
"timestamp": "2025-01-20T16:00:00Z",
"updates": [
{
"id": "content-123",
"version": "1.1.0",
"action": "update",
"url": "https://cdn.example.com/content-123-v1.1.0.zip",
"checksum": "def456..."
},
{
"id": "content-789",
"action": "delete"
}
]
}
```
### 8.2 Delta Sync for Efficiency
```javascript
// Only sync changed portions
{
"deltaSync": {
"baseVersion": "1.0.0",
"targetVersion": "1.1.0",
"patches": [
{
"file": "content/video.mp4",
"operation": "binary_diff",
"patchUrl": "https://cdn.example.com/patches/video-1.0-to-1.1.patch"
},
{
"file": "metadata.json",
"operation": "json_merge",
"changes": {
"title": "Updated Title",
"updatedAt": "2025-01-20T15:00:00Z"
}
}
]
}
}
```
## 9. Security
### 9.1 HTTPS/TLS Requirements
- TLS 1.3 minimum
- Strong cipher suites only
- HSTS (HTTP Strict Transport Security)
- Certificate pinning for mobile apps
### 9.2 Content Encryption
```javascript
// Encrypt content for secure storage
async function encryptContent(content, key) {
const encoder = new TextEncoder();
const data = encoder.encode(content);
const encrypted = await crypto.subtle.encrypt(
{
name: "AES-GCM",
iv: generateIV()
},
key,
data
);
return encrypted;
}
```
### 9.3 Digital Signatures
```bash
# Sign content package
openssl dgst -sha256 -sign private.pem -out signature.bin content.zip
# Verify signature
openssl dgst -sha256 -verify public.pem -signature signature.bin content.zip
```
## 10. Performance Optimization
### 10.1 Compression
- Gzip compression for text assets
- Brotli compression for modern browsers
- Video: H.265/HEVC for better compression
- Images: WebP/AVIF for modern formats
### 10.2 Resource Hints
```html
```
## 11. Monitoring and Analytics
### 11.1 Performance Metrics
Track:
- Time to First Byte (TTFB)
- Content load time
- Playback buffering events
- Error rates
- Geographic distribution
### 11.2 CDN Analytics
```json
{
"analytics": {
"period": "2025-01",
"totalRequests": 1000000,
"bandwidth": 5000000000000,
"cacheHitRate": 0.95,
"edgePerformance": {
"us-east": {"avgLatency": 25, "requests": 400000},
"eu-west": {"avgLatency": 30, "requests": 300000},
"asia-northeast": {"avgLatency": 35, "requests": 300000}
}
}
}
```
---
**WIA-EDU-019 Phase 3 Complete**
弘益人間 · Benefit All Humanity
© 2025 WIA - World Certification Industry Association
MIT License