@synonymdev/feeds
v3.0.0
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A library for creating and managing feeds using the web-relay
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Slashtags Feeds
A library for creating and managing feeds using the web-relay
Usage
const { Client, Relay } = require('@synonymdev/web-relay')
const path = require('path')
const { Feed, Reader } = require('@synonymdev/feeds')
const relay = new Relay(path.join(__dirname, '/storage/relay'));
(async () => {
const relayAddress = await relay.listen()
const client = new Client({ storage: path.join(__dirname, '/storage/writer'), relay: relayAddress })
const icon = Buffer.from('icon-data')
const config = {
name: 'price-feed',
description: 'a price feed',
icons: {
32: 'icon.png'
},
type: 'price-feed',
version: '1.0.0',
fields: [
{
name: 'latest',
description: 'Bitcoin / US Dollar price history',
main: '/feed/BTCUSD-last'
}
]
}
const feed = new Feed(client, config, { icon })
// Wait for config file to be saved
await feed.ready()
confsole.log(feed.config.fields.map(f => f.main)) // ["/feed/BTCUSD-last"]
// may need to wait more for a the relay to get the files from the client in production.
// await new Promise(resolve => settimeout(resolve, 200))
// Update a field, by its name in the config above.
feed.put('latest', 1000000)
{
const client = new Client({ storage: path.join(__dirname, '/storage/reader') })
const reader = new Reader(client, feed.url)
console.log('Config:', await reader.getConfig())
console.log('BTCUSD-last', await reader.getField('latest'))
}
relay.close()
})()
API
const feed = new Feed(client, config, [opts])
Create a Feed instance.
client
is a web-relay client
config
is a feed config file to be saved at ./slashfeed.json
opts
includes:
icon
: an optional icon data as Uint8Array
const url = feed.url
The feed's url in the format slashfeed:<client.id>/<feed-name>/[?query]
await feed.ready()
Await to fetch and populate feed.config
and feed.icon
.
await feeds.put(key, value)
Updates a feed. key
is a string, and value
is Uint8Array, a utf-8 string or a JSON.
await feeds.get(key)
Returns a Uint8Array value from a the local feed.
await feeds.close()
Gracefully closing feeds and the underlying client.
const buffer = Feed.encode(value)
Encodes a value (string, number, null, boolean, array, or object) as JSON and return a Uint8Array
const value = Feed.dcode(buffer)
Decodes a Uint8Array as JSON if possible, or return the Uint8Array itself.
const reader = new Reader(client, url)
Create an instance of the helper Reader
class.
client
is a web-relay client
url
is a feed url feed.url
const config = await reader.getConfig()
Returns the slashfeed.json
configuration file, and sets the reader.config
value. Internally this method gets called as soon as you initialize the Reader instance.
const iconData = await reader.getIcon([size])
Returns the data buffer of the feed icon if it exists. size
is an optional input to choose icon size to fetch, by default it will return the first size in the config.icons
.
const value = await reader.getField(fieldName, [decode])
Returns the value of a specific field.
decode
is an opitonal funciton that expects a Uint8Array
and returns the decoded value.
await reader.subscribe(fieldName, onupdate, [decode])
Returns the value of a specific field.
onupdate(value: T) => any
is a callback function that gets the decoded value as an argument.
decode(buf:Uint8Array) => T
is an opitonal funciton that expects a Uint8Array
and returns the decoded value.
How it works
As of this first version, Slashtags feeds is a directory with the current structure:
├── feed
│ ├── foo
│ ├── bar
└── slashfeed.json
Where slashfeed.json
defines the name
, image
and other future metadata about the feed.
And feed
directory contains the feed files, where each file represents a key value pair.