README.md

FunctionFoundry.Networking

Robust large-data transfer orchestration over HTTP using a caller-provided HttpClient.

What this product does

It plans and executes resumable, integrity-aware downloads with mirror selection and streaming verification.

1. Resumable parallel downloader (ResumableParallelDownloader)

Downloads large objects using HTTP range requests when available:

• ETag / Last-Modified validation
• persistent checkpoint format
• configurable parallelism
• adaptive chunk sizing within min/max bounds (throughput-smoothed)
• corrupt-chunk repair (length mismatch + optional full-digest repair passes)
• partial-file integrity and final cryptographic verification
• safe restart after interruption
• capability detection and correct fallback when ranges are unsupported

Never creates a new HttpClient per request.

2. Mirror selector (MirrorSelector)

Scores candidate mirrors using latency, throughput, availability, and integrity failures:

• failure decay over time
• hysteresis to avoid rapid oscillation
• deterministic tie-breaking
• exportable selection evidence

3. Transfer plan (TransferPlan)

Generates chunk assignments independently from execution:

• resumable state
• incompatible checkpoint detection
• no overlapping writes
• full-coverage verification
• repair assignments after corrupt chunks

4. Streaming integrity verifier (StreamingIntegrityVerifier)

Verifies data while it streams:

• per-chunk and complete-object checks
• detailed mismatch location
• bounded memory (no full-file buffering)

When to use it

• IDE/plugin/runtime update downloaders
• Multi-CDN artifact fetchers
• Resumable media or dataset transfers with integrity requirements

Non-goals

• Owning HttpClient lifetime / DNS / proxy policy for the host
• A general REST client library

Install

dotnet add package FunctionFoundry.Networking

Runtime dependencies

None beyond the .NET shared framework (HttpClient supplied by the caller).