Wiki source code of Networks
Version 35.1 by Zenna Elfen on 2026/01/05 19:51
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| 5 | = Peer-for-Peer Networks = | ||
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| 7 | P4P, short for Peer-4-Peer (which in turn is short for Peer-for-Peer) are a family of networks which build on principles of local-first, peer-2-peer, open-source, routing agnostic (offline-first) and mutual-aid principles. The above is a lot of terms which in and of themselves carry a lot of meaning, yet when combined they enable censorship-resistant, resilient and adaptive, sustainable and energy-efficient communication infrastructures. | ||
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| 17 | == Building Blocks of P4P Networks == | ||
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| 22 | To fully assemble a P4P network one needs a few different building blocks, below is an overview of 15 of those building blocks. Lost in translation? Take a look at the [[terminology>>doc:P4P.Definitions.WebHome]]. | ||
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| 24 | {{box title="==== Contents ==== | ||
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| 26 | ====== ======"}} | ||
| 27 | {{toc depth="5"/}} | ||
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| 42 | ==== ==== | ||
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| 44 | ==== **1. Data Synchronization** ==== | ||
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| 46 | > Synchronization answers **how updates flow between peers** and how they determine what data to exchange. This layer is about **diffing, reconciliation, order, causality tracking, and efficient exchange**, not persistence or user-facing collaboration semantics. | ||
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| 48 | * //How do peers detect differences and synchronize state?// | ||
| 49 | * Examples: Range-Based Set Reconciliation, RIBLT, Gossip-based sync, State-based vs op-based sync, Lamport/Vector/HLC clocks, Braid Protocol | ||
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| 53 | ==== **2. Collaborative Data Structures & Conflict Resolution** ==== | ||
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| 55 | > This layer defines **how shared data evolves** when multiple peers edit concurrently. It focuses on **conflict-free merging, causality, and consistency of meaning**, not transport or storage. CRDTs ensure deterministic convergence, while event-sourced or stream-driven models maintain a history of all changes and derive consistent state from it. | ||
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| 57 | * //How do peers collaboratively change shared data and merge conflicts?// | ||
| 58 | * Examples: CRDTs (Yjs, Automerge), OT, Event Sourcing, Stream Processing, Version Vectors, Peritext | ||
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| 62 | ==== **3. Data Storage & Replication** ==== | ||
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| 64 | > This layer focuses on **durability, consistency, and redundancy**. It handles write-paths, crash-resilience, and replication semantics across nodes. It is the “database/storage engine” layer where **data lives and survives over time**, independent of sync or merging logic. | ||
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| 66 | * //How is data persisted locally and replicated between peers?// | ||
| 67 | * Examples: SQLite, IndexedDB, LMDB, Hypercore (append-only logs), WALs, Merkle-DAGs (IPFS/IPLD), Blob/media storage | ||
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| 71 | ==== **4. Peer & Content Discovery** ==== | ||
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| 73 | > Discovery occurs in two phases: | ||
| 74 | > 1. **Peer Discovery** → finding _any_ nodes | ||
| 75 | > 2. **Topic Discovery** → finding _relevant_ nodes or resources | ||
| 76 | > These mechanisms enable decentralized bootstrapping and interest-based overlays. | ||
| 77 | |||
| 78 | * //How do peers find each other, and how do they discover content in the network?// | ||
| 79 | * Examples: DHTs (Kademlia, Pastry), mDNS, DNS-SD, Bluetooth scanning, QR bootstrapping, static peer lists, Interest-based routing, PubSub discovery (libp2p), Rendezvous protocols | ||
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| 82 | |||
| 83 | ==== **5. Identity & Trust** ==== | ||
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| 85 | > Identity systems ensure reliable mapping between peers and cryptographic keys. They underpin authorization, federated trust, and secure overlays. | ||
| 86 | |||
| 87 | * //How peers identify themselves, authenticate, and establish trustworthy relationships?// | ||
| 88 | * Examples: PKI, Distributed Identities (DIDs), Web-of-Trust, TOFU (SSH-style), Verifiable Credentials (VCs), Peer key fingerprints (libp2p PeerIDs), Key transparency logs | ||
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| 92 | ==== **6. Transport Layer** ==== | ||
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| 94 | > This layer provides logical connections and flow control. QUIC and WebRTC bring modern congestion control and encryption defaults; Interpeer explores transport beyond IP assumptions. | ||
| 95 | |||
| 96 | * //How do peers establish end-to-end byte streams and reliable delivery?// | ||
| 97 | * Examples: TCP, UDP, QUIC, SCTP, WebRTC DataChannels, Interpeer transport stack | ||
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| 101 | ==== **7. Underlying Transport (Physical/Link Layer)** ==== | ||
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| 103 | > Highly relevant for **offline-first / edge networks**, device-to-device communication, and mesh networks and relates to the hardware which facilitates connections. | ||
| 104 | |||
| 105 | * //How does data move across the medium?// | ||
| 106 | * Examples: Ethernet, Wi-Fi Direct / Wi-Fi Aware (post-AWDL), Bluetooth Mesh, LoRa, NFC, Cellular, CSMA/CA, TDMA, FHSS | ||
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| 110 | ==== **8. Session & Connection Management** ==== | ||
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| 112 | > Manages **connection lifecycle**, including authentication handshakes, reconnection after drops, and session continuation—especially important in lossy or mobile networks. | ||
| 113 | |||
| 114 | * //How are connections initiated, authenticated, resumed, and kept alive?// | ||
| 115 | * Examples: TLS handshake semantics, Noise IK/XX patterns, session tokens, keep-alive heartbeats, reconnection strategies, session resumption tickets | ||
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| 119 | ==== **9. Content Addressing** ==== | ||
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| 121 | > Content addressing ensures **immutability, verifiability, and deduplication**. Identity of data = cryptographic hash, enabling offline-first and tamper-evident systems. | ||
| 122 | |||
| 123 | * //How is data addressed and verified by content, not location?// | ||
| 124 | * Examples: IPFS CIDs, BitTorrent infohashes, Git hashes, SHA-256 addressing, Named Data Networking (NDN) | ||
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| 128 | ==== **10. P2P Connectivity** ==== | ||
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| 130 | > Connectivity ensures peers bypass NATs/firewalls to reach each other. | ||
| 131 | |||
| 132 | * //How can two peers connect directly across networks, firewalls, and NATs?// | ||
| 133 | * Examples: IPv6 direct, NAT Traversal, STUN, TURN, ICE (used in WebRTC), UDP hole punching, UPnP | ||
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| 136 | |||
| 137 | ==== **11. Session & Connection Management** ==== | ||
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| 139 | > Manages **connection lifecycle**, including authentication handshakes, reconnection after drops, and session continuation. | ||
| 140 | |||
| 141 | * //How are connections initiated, authenticated, resumed, and kept alive?// | ||
| 142 | * Examples: TLS handshake semantics, Noise IK/XX patterns, session tokens, keep-alive heartbeats, reconnection strategies, session resumption tickets | ||
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| 146 | ==== **12. Message Format & Serialization** ==== | ||
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| 148 | > Serialization ensures **portable data representation**, forward-compatible schemas, and efficient messaging. IPLD provides content-addressed structuring for P2P graph data. | ||
| 149 | |||
| 150 | * //How is data encoded, structured, and made interoperable between peers?// | ||
| 151 | * Examples: CBOR, Protocol Buffers, Cap’n Proto, JSON, ASN.1, IPLD schemas, Flatbuffers | ||
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| 155 | ==== **13. File / Blob Synchronization** ==== | ||
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| 157 | > Bulk data syncing has **different trade-offs** than small collaborative state (chunking, deduplication, partial transfer, resume logic). Critical for media and archival P2P use-cases. | ||
| 158 | |||
| 159 | //How are large objects transferred and deduplicated efficiently across peers?// | ||
| 160 | Examples: BitTorrent chunking, IPFS block-store, NDN segments, rsync-style delta sync, ZFS send-receive, streaming blob transfers | ||
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| 163 | ==== **14. Local Storage & Processing Primitives** ==== | ||
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| 165 | > Provides durable on-device state and local computation (event sourcing, materialization, compaction). Enables offline-first writes and deterministic replay. | ||
| 166 | |||
| 167 | * //How do nodes persist, index, and process data locally—without external servers?// | ||
| 168 | * Examples: RocksDB, LevelDB, SQLite, LMDB, local WALs/append-only logs, embedded stream processors (NATS Core JetStream mode, Actyx-like edge runtimes), Kafka-like libraries | ||
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| 172 | ==== **15. Crash Resilience & Abortability** ==== | ||
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| 174 | > Ensures P2P apps don’t corrupt state on crashes. Tied to **local storage & stream-processing**, and critical in offline-first and distributed update pipelines. Abortability is the updated term for Atomicity as part of the ACID abbreviation. | ||
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| 176 | * //How do nodes recover and maintain correctness under failure?// | ||
| 177 | * Examples: WALs, idempotent ops, partial log replay, transactional journaling, write fences | ||
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| 182 | == Distributed Network Types == | ||
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| 185 | [[Flowchart depicting distributed network variants, under development. Building on work from Z. Elfen, 2024: ~[~[https:~~~~/~~~~/doi.org/10.17613/naj7d-6g984~>~>https://doi.org/10.17613/naj7d-6g984~]~]>>image:P4P_Typology.png||alt="Flowchart depicting typologies of distributed networks, such as Friend-2-Friend, Grassroots Networks, Federated Networks, Local-First, P2P and P4P Networks" data-xwiki-image-style-alignment="center" height="649" width="639"]] | ||
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| 187 | == == | ||
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| 189 | == Overview of P4P Networks == | ||
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| 191 | {{include reference="Projects.WebHome"/}} | ||
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| 200 | ))) |