devol
/
ecosistema-social-decentralizzato
mirror of https://gitlab.com/bluesky-community1/decentralized-ecosystem.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

Fill out data section

This commit is contained in:
Jay Graber 2020-07-02 16:31:41 -07:00
parent 7664fb8318
commit a055623b12
1 changed files with 30 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

42
topics/data.md
View File

@ -1,27 +1,45 @@
# Data
### Data Structures
### Data Models
Shared data structures enable interoperability.
#### Solid
Solid - Solid's data structure is RDF. [RDF](https://www.w3.org/RDF/) uses URIs to name the relationship between things, allowing structured data to be shared across different applications. RDF could potentially [be a barrier to adoption](https://hal.inria.fr/hal-01966561/document), due to its complexity.
Solid's data model is [RDF](https://www.w3.org/RDF/) (Resource Description Framework), which is a standard model for data exchange on the web. RDF was adopted as a W3C recommendation in 1999 as a standard for graph-based data, intended for decentralized information sharing. RDF extends the linking structure of the web to use URIs to name the relationship between things, allowing structured data to be shared across different applications. RDF is based on the idea of [making statements about resources](https://en.wikipedia.org/wiki/Resource_Description_Framework) of the form _subject-predicate-object_, known as triples. It is an abstract model with several serialization formats, so the particular encoding for resources or triples varies.
Matrix - Matrix transports messages using JSON, and tracks conversation history through DAGs.
RDF has all the advantages and generality of structuring information using graphs. It is the foundation for publishing and linking data in the [Semantic Web](https://www.w3.org/standards/semanticweb/). If it were fully adopted, advantages of using RDF would include being able to have the same API everywhere, as opposed to requiring code to integrate with each custom web API. Disadvantages include being non-human-readable and historically [complex to use](https://hal.inria.fr/hal-01966561/document).
Mastodon - ActivityPub uses streams of JSON-LD. Mastodon was formerly compatible with OStatus, which used RSS.
#### XMPP
IPFS - IPFS uses a custom data structure, [IPLD](https://ipld.io/), designed to treat hash-linked data structures as subsets of a unified information space.
XMPP is an XML (Extensible Markup Language) protocol for near-real-time messaging. The basic protocol data unit in XMPP is an XML "stanza", a fragment of XML that is sent over a XML stream.
Ssb - Ssb uses append-only logs of signed JSON.
#### Matrix
Matrix transports messages using JSON, instead of XML like its most similar predecessor, XMPP. In the years since XMPP was standardized, JSON has become a [popular alternative to XML](https://blog.cloud-elements.com/json-better-xml) because it's less verbose, parses quickly, and is human-readable. Conversation history in Matrix is tracked through DAGs.
#### ActivityPub & Mastodon
ActivityPub uses streams of JSON-LD, based on the ActivityStreams data format. Mastodon was formerly compatible with OStatus, which used RSS, but switched entirely to ActivityPub.
AcvitityPub implementations mostly use a [subset of JSON-LD](https://stephank.nl/p/2018-10-20-a-proposal-for-standardising-a-subset-of-json-ld.html), related to namespacing, versioning, and extensions. JSON-LD allows for extensibility, so that ActivityStreams do not have to contain all the vocabulary needed for future applications.
#### IPFS
IPFS uses a custom data structure, [IPLD](https://ipld.io/), which is designed to treat hash-linked data structures as subsets of a unified information space. IPLD is a single namespace for all hash-based protocols, such as git and cryptocurrencies. IPLD objects can be expressed in various serialized formats such as JSON, CBOR, YAML, and XML.
#### Ssb
Ssb uses append-only logs of signed JSON. Each ssb user has their own [signed hash-based linked list](https://spec.scuttlebutt.nz/feed/messages.html), called a _sigchain_. This design ensures that messages are not lost, the order is not confused, data can be moved across untrusted machines, and replication of data is simple. Drawbacks include the inability to subscribe to only parts of the data, no support for mutable data, and the inability to update from multiple machines, resulting in no multi-device usage.
#### Hypercore
The Dat project renamed to Hypercore to reflect a transition that placed the core of the protocol at a lower level of abstraction. The focus of Hypercore is a signed append-only log that is p2p distributed, and its main purpose is to be a building block for other applications. The core of Dat, a public-key-addressed file drive, is now implemented as Hyperdrive on top of Hypercore. In contrast to ssb, which uses a linked-list append-only log, Hypercore uses a Merkle-tree-based append-only log where each entry generates a new leaf and new root
### Mutability
Federated applications allow users to edit and delete content, handled at the server level. Content may not be guaranteed to be deleted across the entire network in some cases - protocols should require applications to honor delete messages.
P2p applications have more variance around mutability.
Federated applications allow users to edit and delete content, handled at the server level. To ensure content is deleted across the entire network, applications must honor delete messages. P2p applications have more variance around mutability.
Ssb & Hypercore - Messages added to the append-only logs used by ssb and hypercore are immutable. Applications can choose not to display messages indicated as deleted, but the data cannot be overwritten.
IPFS - Once added to a network, content is discoverable by its hash. If a copy remains stored on the network, it is re-discoverable by this reference.
IPFS - Data is content-addressed, so once added to a network, content is discoverable by its hash. If users stop hosting it and no copies are left online, it will be inaccessible. However, if a copy remains stored on the network, it is re-discoverable by its immutable reference hash.
Aether - "Stale" threads that have not been referenced for 6 months get dropped by the network. This design attempts to make posts more ephemeral in a p2p setting.
Aether - Aether attempts to design a more ephemeral p2p content network. "Stale" threads that have not been referenced for 6 months get dropped by clients in the network.