With the long awaited geth 1.5 (“let there bee light”) release, Swarm made it into the official go-ethereum release as an experimental feature. The current version of the code is POC 0.2 RC5 — “embrace your daemons” (roadmap), which is the refactored and cleaner version of the codebase that was running on the Swarm toynet in the past months.

The current release ships with the swarmcommand that launches a standalone Swarm daemon as separate process using your favourite IPC-compliant ethereum client if needed. Bandwidth accounting (using the Swarm Accounting Protocol = SWAP) is responsible for smooth operation and speedy content delivery by incentivising nodes to contribute their bandwidth and relay data. The SWAP system is functional but it is switched off by default. Storage incentives (punitive insurance) to protect availability of rarely-accessed content is planned to be operational in POC 0.4. So currently by default, the client uses the blockchain only for domain name resolution.

With this blog post we are happy to announce the launch of our shiny new Swarm testnet connected to the Ropsten ethereum testchain. The Ethereum Foundation is contributing a 35-strong (will be up to 105) Swarm cluster running on the Azure cloud. It is hosting the Swarm homepage.

We consider this testnet as the first public pilot, and the community is welcome to join the network, contribute resources, issues, identify painpoints and give feedback on useability. Instructions can be found in the Swarm guide. We encourage those who can afford to run persistent nodes (nodes that stay online) to get in touch. We have already received promises for 100TB deployments. Note that the testnet offers no guarantees! Data may be lost or become unavailable. Indeed guarantees of persistence cannot be made at least until the storage insurance incentive layer is implemented.

Note that the testnet offers no guarantees! Data may be lost or become unavailable. Indeed guarantees of persistence cannot be made at least until the storage insurance incentive layer is implemented.

We envision shaping this project with more and more community involvement, so we are inviting those interested to join

How does Swarm work?

Swarm is a distributed storage platform and content distribution service; a native base layer service of the ethereum Web3 stack. The objective is a peer-to-peer storage and serving solution that has zero downtime, is DDOS-resistant, fault-tolerant and censorship-resistant as well as self-sustaining due to a built-in incentive system. The incentive layer uses peer-to-peer accounting for bandwidth, deposit-based storage incentives and allows trading resources for payment. Swarm is designed to deeply integrate with the devp2p multiprotocol network layer of Ethereum as well as with the Ethereum blockchain for domain name resolution.

Swarm’s main offering as a distributed chunkstore is that you can upload content to it. The nodes constituting the Swarm all dedicate resources (diskspace, memory, bandwidth and CPU) to store and serve chunks. But what determines who is keeping a chunk? Swarm nodes have an address (the hash of the address of their bzz-account) in the same keyspace as the chunks themselves. Lets call this address space the overlay network. If we upload a chunk to the Swarm, the protocol determines that it will eventually end up being stored at nodes that are closest to the chunk’s address (according to a well-defined distance measure on the overlay address space). The process by which chunks get to their address is called syncing and is part of the protocol. Nodes that later want to retrieve the content can find it again by forwarding a query to nodes that are close the the content’s address. Indeed, when a node needs a chunk, it simply posts a request to the Swarm with the address of the content, and the Swarm will forward the requests until the data is found (or the request times out). In this regard, Swarm is similar to a traditional distributed hash table (DHT) but with two important (and under-researched) features.

• Vitalik’s whitepaper the Ethereum dev core realised
• When she reached the first hills
• A small river named Duden flows
• Self-sustaining due to a built-in incentive system

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Documents and the Swarm hash

On the API layer Swarm provides a chunker. The chunker takes any kind of readable source, such as a file or a video camera capture device, and chops it into fix-sized chunks. These so-called data chunks or leaf chunks are hashed and then synced with peers. The hashes of the data chunks are then packaged into chunks themselves (called intermediate chunks) and the process is repeated. Currently 128 hashes make up a new chunk. As a result the data is represented by a merkle tree, and it is the root hash of the tree that acts as the address you use to retrieve the uploaded file.