Expose a leveldb over the network.
npm install multilevelExpose a levelDB over the network, to be used by multiple processes,
with levelUp's API.
Expose a db on the server:
``js
var multilevel = require('multilevel');
var net = require('net');
var level = require('level');
var db = level('/my/db');
net.createServer(function (con) {
con.pipe(multilevel.server(db)).pipe(con);
}).listen(3000);
`
And connect to it from the client:
`js
var multilevel = require('multilevel');
var net = require('net');
var db = multilevel.client();
var con = net.connect(3000);
con.pipe(db.createRpcStream()).pipe(con);
// asynchronous methods
db.get('foo', function () { / / });
// streams
db.createReadStream().on('data', function () { / / });
`
multilevel works in the browser too - via
browserify - and has full
support for binary data. For getting a connection between browser and server I
recommend either
websocket-stream, which treats
binary data well, or
engine.io-stream, which has
websocket fallbacks.
When using a binary capable transport, require multilevel like this:
`js`
var multilevel = require('multilevel/msgpack');
This way it uses msgpack-stream
instead of json-buffer which uses
way less bandwidth - but needs a binary capable transport.
You can also expose custom methods and sublevels
with multilevel!
When using plugins, you must generate a manifest and require it in the client.
Here's an example:
` jsdb
// server.js
// create
var level = require('level');
var multilevel = require('multilevel');
var db = level(PATH);
// extend db with a foo(cb) method
db.methods = db.methods || {};
db.methods['foo'] = { type: 'async' };
db.foo = function (cb) {
cb(null, 'bar');
};
// now write the manifest to a file
multilevel.writeManifest(db, __dirname + '/manifest.json');
// then expose db via shoe or any other streaming transport.`
var shoe = require('shoe');
var sock = shoe(function (stream) {
stream.pipe(multilevel.server(db)).pipe(stream);
});
sock.install(http.createServer(/ ... /), '/websocket');
Manifests are generated using
level-manifest, which doesn't
only support async functions but e.g. streams as well. For more, check its README.
Then require the manifest on the client when bundling with browserify or in
any other nodejs compatible environment.
` jsmanifest.json
// client.js
// instantiate a multilevel client with the we just generated
var multilevel = require('multilevel');
var manifest = require('./manifest.json');
var db = multilevel.client(manifest);
// now pipe the db to the server
var stream = shoe('/websocket');
stream.pipe(db.createRpcStream()).pipe(stream);
// and you can call the custom foo method!`
db.foo(function (err, res) {
console.log(res); // => "bar"
});
You do not want to expose every database feature to every user, you might e.g.
only want to provide read-only access to some users.
Auth controls may be injected when creating the server stream.
In this example, allow read only access, unless logged in as root.
`js
//server.js
var db = require('./setup-db'); //all your database customizations
var multilevel = require('multilevel');
//write out manifest
multilevel.writeManifest(db, __dirname + '/manifest.json');
shoe(function (stream) {
stream.pipe(multilevel.server(db, {
auth: function (user, cb) {
if (user.name == 'root' && user.pass == 'toor') {
//the data returned will be attached to the mulilevel stream
//and passed to access
cb(null, {name: 'root'});
} else {
cb(new Error('not authorized');
}
},
access: function (user, db, method, args) {
// is the {name: 'root'} object that auth
//returned.
//if not a privliged user...
if (!user || user.name !== 'root') {
//do not allow any write access
if (/^put|^del|^batch|write/i.test(method)) {
throw new Error('read-only access');
}
}
})
})).pipe(stream);
});
// ...
`
The client authorizes by calling the auth method.
` js
var multilevel = require('multilevel');
var shoe = require('shoe');
var stream = shoe();
var db = multilevel.client();
stream.pipe(db.createRpcStream()).pipe(stream);
db.auth({ name: 'root', pass: 'toor' }, function (err, data) {
if (err) throw err
//later, they can sign out, too.
db.deauth(function (err) {
//signed out!
});
});
`
The exposed DB has the exact same API as
levelUp, except
* db#close() closes the connection, instead of the database.db#isOpen()
* the synchronous versions of and db#isClose() tell you if youdb.on("put", ...)
currently have a connection to the remote db.
* events, like are not emitted. If you need updates, you
can use level-live-stream.
Returns a server-stream that exposes db, an instance of levelUp.authOpts is optional and should be of this form:
` js`
var authOpts = {
auth: function (userData, cb) {
//call back an error, if the user is not authorized.
},
access: function (userData, db, method, args) {
//throw if this user is not authorized for this action.
}
}
It is necessary that you create _one server stream per client_.
Synchronoulsy write db's manifest to path.
Also returns the manifest as json.
Return a new client db. manifest may optionally be provided, which will
grant the client access to extensions and sublevels.
#### db.createRpcStream()
Pipe this into a server stream.
Listen for the error event on this stream to handle / swallow reconnect events.
#### db.auth(data, cb)
Authorize with the server.
#### db.deauth (cb)
Deauthorize with the server.
On my macbook pro one multilevel server handles ~15k ops/s over a local tcp
socket.
`js
∴ bench (master) : node index.js
writing "1234567890abcdef" 100 times
native : 2ms (50000 ops/s)
multilevel direct : 21ms (4762 ops/s)
multilevel network : 14ms (7143 ops/s)
writing "1234567890abcdef" 1000 times
native : 12ms (83333 ops/s)
multilevel direct : 71ms (14085 ops/s)
multilevel network : 77ms (12987 ops/s)
writing "1234567890abcdef" 10000 times
native : 88ms (113636 ops/s)
multilevel direct : 594ms (16835 ops/s)
multilevel network : 590ms (16949 ops/s)
writing "1234567890abcdef" 100000 times
native : 927ms (107875 ops/s)
multilevel direct : 10925ms (9153 ops/s)
multilevel network : 9839ms (10164 ops/s)
`
With npm do:
`bash`
$ npm install multilevel
`bash``
$ npm install
$ npm test
$ npm run test-browser
This module is proudly supported by my Sponsors!
Do you want to support modules like this to improve their quality, stability and weigh in on new features? Then please consider donating to my Patreon. Not sure how much of my modules you're using? Try feross/thanks!
(MIT)
Copyright (c) 2013 Julian Gruber <julian@juliangruber.com>
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