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WASM Edge Computing: Advanced Topics

WASM Edge Computing: Advanced Topics

Part of: WASM Edge Computing User Guide

Custom CDN Integration

use heliosdb_wasm::edge::cdn::{CdnProvider, CdnAdapter};


// Implement custom CDN adapter
struct CustomCdnAdapter {
    api_endpoint: String,
    api_key: String,
}


impl CdnAdapter for CustomCdnAdapter {
    async fn deploy(&self, function: &str, wasm: &[u8], version: &str) -> Result<String> {
        // Custom deployment logic
        let response = self.api_client
            .post(&format!("{}/deploy", self.api_endpoint))
            .header("Authorization", &format!("Bearer {}", self.api_key))
            .body(wasm)
            .send()
            .await?;


        Ok(response.deployment_id)
    }


    async fn purge_cache(&self, keys: Vec<String>) -> Result<()> {
        // Custom cache purge logic
        Ok(())
    }
}


// Register custom adapter
cdn_manager.register_custom_adapter(
    "my_cdn",
    Box::new(CustomCdnAdapter {
        api_endpoint: "https://api.mycdn.com".to_string(),
        api_key: std::env::var("MY_CDN_API_KEY")?,
    }),
).await?;

CRDT Customization

use heliosdb_wasm::edge::sync::CrdtOperation;


// Custom CRDT: Observed-Remove Set
struct ObservedRemoveSet {
    adds: HashMap<String, u64>,    // element -> timestamp
    removes: HashMap<String, u64>, // element -> timestamp
}


impl ObservedRemoveSet {
    pub fn add(&mut self, element: String, timestamp: u64) {
        self.adds.insert(element, timestamp);
    }


    pub fn remove(&mut self, element: String, timestamp: u64) {
        // Only remove if we've seen the add
        if let Some(&add_ts) = self.adds.get(&element) {
            if timestamp > add_ts {
                self.removes.insert(element, timestamp);
            }
        }
    }


    pub fn contains(&self, element: &str) -> bool {
        if let Some(&add_ts) = self.adds.get(element) {
            if let Some(&remove_ts) = self.removes.get(element) {
                // Element was added, then removed
                return add_ts > remove_ts;
            }
            // Element was added, never removed
            return true;
        }
        false
    }


    pub fn merge(&mut self, other: &ObservedRemoveSet) {
        for (element, &timestamp) in &other.adds {
            let entry = self.adds.entry(element.clone()).or_insert(0);
            *entry = (*entry).max(timestamp);
        }


        for (element, &timestamp) in &other.removes {
            let entry = self.removes.entry(element.clone()).or_insert(0);
            *entry = (*entry).max(timestamp);
        }
    }
}

Multi-Region Writes

// Configure multi-region write coordination
let config = SyncConfig {
    consistency_model: ConsistencyModel::Causal,
    sync_interval: Duration::from_millis(50),
    enable_delta_sync: true,
    enable_compression: true,
    ..Default::default()
};


// Write to local region
sync.put("global:key".to_string(), data, None).await?;


// Propagate to specific regions
let priority_regions = vec![
    Region::UsEast1,
    Region::EuWest1,
    Region::ApNortheast1,
];


for region in priority_regions {
    sync.sync_with_region(region).await?;
}


// Wait for propagation
let mut attempts = 0;
loop {
    let propagated = check_propagation("global:key", &priority_regions).await?;


    if propagated {
        break;
    }


    attempts += 1;
    if attempts > 10 {
        return Err(Error::PropagationTimeout);
    }


    tokio::time::sleep(Duration::from_millis(50)).await;
}

Edge Analytics

// Custom analytics at edge
#[heliosdb_edge_function]
pub async fn tracked_handler(ctx: &EdgeContext) -> Result<Value> {
    let start = Instant::now();


    // Track request
    ctx.analytics.record_request(
        ctx.request.path(),
        ctx.request.method(),
        ctx.client_region(),
    ).await?;


    // Execute handler
    let result = handle_request(ctx).await;


    // Track response
    let latency = start.elapsed();
    let status = result.as_ref().map(|_| 200).unwrap_or(500);


    ctx.analytics.record_response(
        latency,
        status,
        result.as_ref().map(|r| r.size_bytes()).unwrap_or(0),
    ).await?;


    result
}


// Query analytics
let analytics = ctx.analytics.query(QueryParams {
    time_range: TimeRange::Last24Hours,
    group_by: vec![Dimension::Region, Dimension::Path],
    metrics: vec![Metric::RequestCount, Metric::AvgLatency, Metric::ErrorRate],
}).await?;

Cost Optimization

// Analyze costs by region and CDN
let cost_analysis = analytics.get_cost_analysis().await?;


println!("=== Monthly Cost Breakdown ===");
for (provider, cost) in cost_analysis.by_provider {
    println!("{}: ${:.2}", provider.name(), cost);
}


println!("\n=== Cost by Region ===");
for (region, cost) in cost_analysis.by_region {
    println!("{}: ${:.2}", region.name(), cost);
}


// Optimize by reducing deployment footprint
let underutilized_regions = cost_analysis.by_region
    .iter()
    .filter(|(_, cost)| **cost > 100.0)
    .filter(|(region, _)| {
        let traffic = analytics.get_region_traffic(region).await.unwrap();
        traffic.requests_per_day < 1000
    })
    .map(|(region, _)| region)
    .collect::<Vec<_>>();


for region in underutilized_regions {
    println!("Consider removing deployment from {}", region.name());
}