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multi-master replication with transformations
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multi-master replication with transformations


  • built on the principle of owning your own data:
    • you decide what you want to share, with who and how
    • don't rely on a third party (i.e. a cloud service)
    • privacy and security by design
  • multi-master replication with transformations
  • support for browsers via IndexedDB and WebSockets (see browser)
  • support for MongoDB

Status: alpha

Currently deploying the software into a controlled production environment.


Note: Node.js 4.x is required.

Clone this repo and change your working dir to it:

$ git clone
$ cd PerspectiveDB

Install npm modules:

$ npm install

Ensure a database root directory exists, i.e. /var/pdb:

$ sudo mkdir /var/pdb

Ensure an empty directory exists for chrooted processes, i.e. /var/empty:

$ sudo mkdir /var/empty

Create a dedicated system user for the main process:

$ sudo useradd -d /var/empty -r -s /bin/false -U _pdbnull

Create a dedicated system user for the database process:

$ sudo useradd -d /var/empty -r -s /bin/false -U pdblevel

Create a user account database:

$ omask=$(umask); umask 077 && touch config/local/passwd.hjson; umask $omask

Grant access to a user for remote login, i.e. setup a password for user "john":

$ ./bin/adduser john >> config/local/passwd.hjson

Create a config file. I.e. copy and edit example.hjson:

$ cp config/examples/example.hjson config/local/pdb.hjson

Start the server:

$ sudo bin/pdb config/local/pdb.hjson

By default a tcp server is started on port 2344. Communication between different servers should be done over an ssh tunnel.

Communicate with browsers

Add a WebSocket server

Communication with browsers can be done using a WebSocket. It is required to start the WebSocket server over a modern TLS connection with forward secrecy.

Generate the following files:

  • DH parameters
  • private key
  • temporary CSR
  • self signed certificate (or use a certificate signed by one of the major CAs)
$ umask 077
$ openssl dhparam -outform PEM -out config/local/dhparam.pem 2048
$ openssl genrsa -out config/local/key.pem 2048
$ umask 022
$ openssl req -new -sha256 -key config/local/key.pem -out config/local/csr.pem
$ openssl x509 -req -in config/local/csr.pem -signkey config/local/key.pem -out config/local/cert.pem
$ rm config/local/csr.pem

Edit your config to enable the WebSocket server and include these three files. Relative paths are relative to the directory of the config file.

Run the web client

A web client is included in the browser directory. Use a local webserver like http-server or python -m SimpleHTTPServer 8080 to run the example in browser/example.

SSH tunnels

In order to communicate with external hosts an SSH tunnel must be used. Different tunnels can be setup by PerspectiveDB. For those familiar, this works just like the ssh -L command. Say PerspectiveDB runs on Then the following is an example of a tunnel to the machine at Every connection on to will be tunneled to

tunnels: [
    connect: ssh://
    fingerprint: DR5pI2uaxhQDyem9Cf0tQQ3RivlbC7jmJn5kkWpiY2g
    key: /home/john/.ssh/myidentity.key
    sshUser: john
    forward: 1337:

Two things are important: the identity of the remote host, and the idenity of PerspectiveDB. The identity of the remote host is listed under the key fingerprint. It's a base64 encoded sha256 hash of the identity of the remote party. It can be achieved by running ssh-keygen -E sha256 -lf /etc/ssh/ on (-E is supported since ssh 6.9). If the public key of is located in some other file (i.e. your known_hosts), then ssh-keygen -E sha256 -lf ~/.ssh/known_hosts can be run.

The identity of PerspectiveDB is listed under the key key. It is a private key on Currently only RSA keys without a password are supported. A new one can be created as follows: ssh-keygen -t rsa -f /home/john/.ssh/myidentity.key. Leave the password empty.

A tunnel can be used by anyone on the machine, not only PerspectiveDB. To use a tunnel with the mongodb adapter and connect to the database somedb on one can use something like:

dbs: [
    name: mydb
    source: {
      url: mongodb://

Mirror a MongoDB database

A special mongodb adapter is included that can be used to track changes in mongodb. See adapter/mongodb/ for further instructions.


Copyright 2012-2016 Netsend.

This file is part of PerspectiveDB.

PerspectiveDB is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

PerspectiveDB is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with PerspectiveDB. If not, see

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