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MAGE User Guide

Here you will find both the basic documentation for MAGE. If you are looking for API documentation, please have a look at the API reference.

Questions and issues

If you have a question which is not covered by the current documentation:

  1. Open an issue and request an addition to the documentation
  2. If you have some time, please make a pull request to enhance the documentation

Introduction

MAGE is a Game Server Framework for Node.js. It allows game developers to quickly create highly interactive games that are performant and scalable.

Why MAGE?

Write interactive games

Even if you are writing a single-player game, you may want to develop features such as ranking and shops, store player information, or send push notifications to your game clients.

MAGE makes this easy by providing both a framework to create RPC calls (called user commands), and by providing a backend API to send asynchronous messages between players.

Write multiplayer games

MAGE’s forte comes down to writing multiplayer games. MAGE is an excellent fit for writing PVP games.

Scalable game servers

One of MAGE’s goal is to make it easy to write game servers that scale.

But scale how? More specifically, MAGE helps you:

Rich ecosystem

MAGE provides only the primitives required to write interactive games. However, MAGE comes with a rich ecosystem of official and third-party modules that will help you add features such as static data management, maintenance management, and so on.

Official MAGE modules can be found on GitHub. We also often showcase external modules (and how to use them) on our development blog.

Features

TypeScript & JavaScript

MAGE actively supports both JavaScript and TypeScript projects; you can easily choose in which language you wish to create a project, and many tools support both languages.

Transactional API endpoints

This is the core feature of MAGE; it provides you with a State API that helps you create transactional API endpoints.

Transactional API endpoints (named user commands) will allow you to stack all your data mutations and asynchronous messages on a state object. This state object will either automatically be commited once your API call completes, or rollback if an error occurs.

Multiple storage backends

The data storage API allows you to abstract your storage backend. Not only it will allow you to access and store data to your database of choice, but it will also help you with database migrations whenever needed.

Built-in distributed mode

Thanks to the built-in service discovery system, all you need to do to deploy your game server in a cluster is configure the discovery service.

This means that your messages will always be routed to the right server and correctly forwarded to the right player.

Rich ecosystem of SDKs, modules and tools

MAGE officially provides client SDKs for both HTML5 and Unity games, making it easier than ever to connect your game to your servers.

On top of that, the mage organization on GitHub hosts a wide range of additional tools and modules which can help you with various aspects of your MAGE development pipeline.

Requirements

Node.js

nvm install 8
nvm use 8

# You will need to provide the specific version to install and use
Install-NodeVersion v8.10.0
Set-NodeVersion v8.10.0

Node.js (or Node) is essentially JavaScript for servers, and the MAGE platform has been built on it. There are some concepts you will most likely benefit from understanding before getting started on a serious Node project. Here are some resources which might help you make your first steps on Node:

We recommend using the following Node.js version manager depending on your platform:

NPM

NPM command completion is not available on Windows

npm install -g npm@latest
npm completion >> ~/.bashrc

npm run [tab][tab]
# Will output: archivist:create   archivist:drop     archivist:migrate  develop  [...]

npm install -g npm@latest

NPM will ship by default with your Node.js installation. However, since bugs are fixed in later versions, we strongly recommend to periodically update your NPM installation to make sure to get all the fixes.

This project, as well as the projects it generates on bootstrap, use NPM for all its build task. Therefore, we also recommend to set up NPM command completion in your terminal. See https://docs.npmjs.com/cli/completion for more details.

Installation

Naming your environment

You can replace “development” with something else if you want

export NODE_ENV=development

set-item env:NODE_ENV=development

When MAGE creates a new project, it will set up a configuration file for your environment. The name of your environment is decided by the NODE_ENV environment variable. If your system administrator has not already prepared it for you on the system you are developing on, you can do it yourself by adding the above line your shell’s profile file (.bashrc, .zshrc, profile.ps1, and so on).

The MAGE installer will create a development.yaml configuration file, and will use that from there on, whenever you start up the game.

Setting up a new MAGE project

As a JavaScript project

Replace my-gameserver with how you wish to name your game

# Note: use npx, not npm!
npx mage create my-gameserver
cd my-gameserver

# Note: use npx, not npm!
npx mage create my-gameserver
cd my-gameserver

Then use the following command to start your game server (ctrl+c to exit)

npm run develop

npm run develop

Running the following steps is the easiest way to create a new project. Do this from inside an empty folder that is named after the game you are developing.

You can also specify which version you wish to install by adding @[version number] at the end of the line.

As a TypeScript project

# Note: use npx, not npm!
npx mage create my-gameserver --typescript
cd my-gameserver

npx mage create my-gameserver --typescript
cd my-gameserver

MAGE can also create TypeScript projects; to do so, all you need to do is to add the typescript or ts flag to the previous command.

Upgrading MAGE in an existing project

In some cases, you may want to npm run clean first.

npm install --save mage@1.2.3

npm install --save mage@1.2.3

To upgrade to a new version of MAGE, simply re-run install with the --save flag, and specify the version you wish to now use.

Versioning of MAGE

MAGE version numbering follows Semantic Versioning or “semver” logic.

That means that given a version number MAJOR.MINOR.PATCH, we increment the:

Working with master (latest) and development

npm install --save mage/mage#master

npm install --save mage/mage#master

You may choose, for the duration of your application development, to work on a pre-release version of MAGE. To do so, you can use the master branch when running npm install.

API Reference

Before you jump into the API documentation, you will most likely want to read through this document so to get familiar with the basics of MAGE.

API documentation

Client SDKs

The following client SDKs are currently available to connect your game client to a MAGE server:

Name Language Location
mage-js-sdk JavaScript (browser) GitHub
mage-sdk-unity C# (For Unity) GitHub

Some SDKs may have optional sub-libraries to be installed depending on which MAGE functionality your game will be using.

Configuration

Format

The configuration for your game is allowed to exist in the YAML format with the .yaml file extension, the JSON format with the .json file extension, or the JSON5 format with the .json5 file extension.

In a nutshell, YAML is the more human readable format, while JSON is more JavaScript-like in how it represents its variable types. JSON5 represents a good middle-ground between both previous formats.

Location

config/

config
├── custom.yaml
├── default.yaml
├── development.yaml
└── production.yaml

The files are located in your game’s config folder.

Configuration files will be loaded in the following order:

  1. config/default.yaml: The base configuration file for your project
  2. config/[NODE_ENV].yaml: Configuration for a specific environment
  3. config/custom.yaml: Configuration for your local setup

If you want to load multiple configuration files, you may comma-separate them in your NODE_ENV like this: NODE_ENV=bob,test. They will be loaded in order, the latter overriding the former.

Custom configuration is generally used during development; in some cases, developers will need to specify their own credentials or personalized configuration. Newly created projects will include a custom file; however, this file will also be added to your .gitignore file to avoid any conflicts between each developer’s configuration.

Development

This turns on all options

developmentMode: true

Alternatively, take control by toggling the individual options. The ones you leave out are considered to be set to true. Set any of the following to false to change the default development mode behavior.

developmentMode:
    archivistInspection: true  # Archivist will do heavy sanity checks on queries and mutations.

To run your game in development, MAGE has a developmentMode configuration flag. This enables or disables certain behaviors which make development a bit more convenient. If you want more granular control over which of these behaviors are turned on or off, you can specify them in an object.

Environment-based configuration

server:
    clientHost:
      bind: MAGE_APP_BIND:string

    mmrp: MAGE_APP_MMRP:bool

You may also add a config/environment.yaml file to your project: this file serves as a means to connect environment variables to specific configuration entries. Environment variables will supersede any configuration set through configuration files.

In this example, we connect MAGE_APP_BIND and MAGE_APP_MMRP to our configuration. Note you may also optionally specify the type to cast the environment variable into. In this case for instance, we set MAGE_APP_MMRP as a boolean because we might want to disable MMRP it by running MAGE_APP_MMRP=false npm run mage or otherwise setting the value into the environment.

Dynamic configuration

test/index.js

const config = require('mage/lib/config');
config.set('some.path.to.config', 1)

const mage = require('mage');

// continue with your test code

The moment mage is required or imported, it will automatically set up the configuration management API as well as read configuration files. However, in some cases - such as unit testing - you might want to forcibly disable certain services, or enforce fixed behaviors.

To do so, you have the option of requiring MAGE’s configuration before, fix your configuration; once you require MAGE, your dynamic configuration will then be applied.

You may dynamically set a new configuration at any time while the MAGE server is running; however, keep in mind that most modules only read configuration entries at runtime, and therefore dynamically changing the configuration after MAGE has been initialized will likely not have any effects.

Modules

External helper modules

External helpers modules are optional but simplify the use of the library. They are different from mage built-in modules and user modules: they don’t expose usercommands, they just act as helpers.

Here are the most important:

Module Description TypeScript library
mage-console Mage development console with REPL interface and auto-reload on file change
mage-validator Validation system for MAGE topics and user command input types ✔
mage-module-shard Helps you to implement modules that act as shards within a MAGE cluster ✔
mage-vaulthelper-couchbase Helps you to access mage Couchbase backend ✔
mage-module-maintenance Helps you implement a maintenance mode for your game cluster ✔
mage-https-devel Toolchain for enabling the use of HTTPS during local development

Built-in modules

lib/index.js

// Default modules with a fresh mage install
// (with npx mage create [game name])
mage.useModules([
  'archivist',
  'config',
  'logger',
  'session',
  'time'
]);

In the mage library, some modules are already created to provide some facilities such as session and authentication. The full list of available modules is defined as below:

Module Description
archivist Expose usercommands to synchronize data in real time
config Expose client config with a usercommand
auth Authentication facility
logger Logging facility
session Session facility
time Time manipulation facility

To see the default modules on a fresh install of mage and how they can be set up, see the example on the right side. Note that the auth module is not activated by default.

Set up the auth module

To set up the auth module, adding it to mage.useModules is not sufficient, a basic configuration is needed. See the example on the right side for a basic configuration.

Here are the different hash types you can use:

Type Description
pbkdf2 pbkdf2 algorithm
hmac hmac algorithm
hash Basic hash

lib/index.js

mage.useModules([
  'auth'
]);

lib/archivist/index.js

// a valid topic with ['username'] as an index
exports.auth = {
  index: ['username'],
  vaults: {
    myDataVault: {}
  }
};

config/default.yaml

module:
    auth:
        # this should point to the topic you created
        topic: auth

        # configure how user passwords are stored, the values below are the
        # recommended default
        hash:
            # Please see https://en.wikipedia.org/wiki/PBKDF2 for more information
            type: pbkdf2
            algorithm: sha256
            iterations: 10000

        hash:
          # Please see https://en.wikipedia.org/wiki/HMAC for more information
          type: hmac
          algorithm: sha256
          # Hex key of any length
          key: 89076d50860489076d508604

        hash:
          # Basic hash
          type: hash
          algorithm: sha1

File structure

mygame/
  lib/
    modules/
      players/    -- the name of our module
        index.js  -- the entry point of the module
        usercommands/
          login.js  -- the user command we use to login

Modules are a way to separate concerns; they contain groups of functionality for a certain subject (users, ranking, shop, etc), and expose API (called user commands) that are accessible through the different client SDKs.

Module setup and teardown

lib/modules/players/index.js

exports.setup = function (state, callback) {
  // load some data
  callSomething('someData', callback);
};

exports.teardown = function (state, callback) {
  // load some data
  callSomething('someData', callback);
};

MAGE modules can optionally have the two following hooks:

The setup function will run when MAGE boots up allowing your module to prepare itself, for example by loading vital information from a data store into memory. This function is optional, so if you do not have a setup phase, you don’t need to add it.

Teardown functions in a similar way; you may want to store to database some data you have been keeping in memory, or send some notifications to your users.

Note that by default, each hook will have 5000 milliseconds to complete; should you need longer than that, you will need to set exports.setupTimeout and exports.teardownTimeout respectively to the value of your choice.

Module methods

lib/modules/players/index.js

var mage = require('mage');

exports.register = function (state, username, password, callback) {
  var options = {
    acl: ['user']
  };

  mage.auth.register(state, username, password, { options }, callback);
};

You will then want to add methods to your modules. These are different from your API endpoints; they are similar to model methods in an MVC framework, but they are not attached to an object instance.

This example shows how you could create a quick player registration method.

User commands

lib/modules/players/usercommands/register.js

var mage = require('mage');

// Who can access this API?
exports.acl = ['*'];

// The API endpoint function
exports.execute = function (state, username, password, callback) {
  mage.players.register(state, username, password, function (error, userId) {
    if (error) {
      return state.error(error.code, error, callback);
    }

    state.respond(userId);

    return callback();
  });
};

User commands are the endpoints which the game client will be accessing. They define what class of users may access them, and what parameters are acceptable.

The name of a user command is composed of its module name and the name of the file. For instance, in the example here, the name of the user command would be players.register. The parameters this user command accepts are everything between the state parameter and the callback parameter; so in this case, players.register accepts a username parameter, and a password parameter.

Our user command also receives a state object. We won’t describe exactly what states are used for yet, but we can see that they are to be used to respond with an error should one occur.

Testing your user command

npm run archivist:create
npm run develop

npm run archivist:create
npm run develop

Before we try to test the code above, we will first need to create a place for the auth module to store the data. archivist:create will do just that.

Once this command completes, we’ll start our MAGE project in development mode.

In a separate terminal window

curl -X POST http://127.0.0.1:8080/game/players.register \
--data-binary @- << EOF
[]
{"username": "test","password": "secret"}
EOF

 Invoke-RestMethod -Method Post -Uri "http://127.0.0.1:8080/game/players.register" -Body '[]
{"username": "username", "password": "password"}' | ConvertTo-Json

For testing most user commands in MAGE, you would normally need to use one of the client SDKs; however, this example is simple enough for us to be able to simply query the endpoint manually.

You may notice that the content we send is in line-separated JSON format, and that the first thing we send is an empty array; this array, under normal circumstances, would contain credentials and other metadata.

Login

lib/modules/players/index.js

var mage = require('mage');

exports.register = function (state, username, password, callback) {
  var options = {
    acl: ['user']
  };

  mage.auth.register(state, username, password, options,  function (error, userId) {
    if (error) {
      return callback(error);
    }

    mage.logger.debug('Logging in as', userId);

    mage.auth.login(state, username, password, callback);
  });
};

Now that we can register users, we may want to automatically log in the user by calling mage.auth.login. While the registration has not been completed in the database, our state transaction contains the information for the newly registered user, which will allow for login to complete successfully.

For more information about the auth module, please refer to the API documentation.

ACLs

lib/modules/players/usercommands/notAccessibleToNormalUers.js

var mage = require('mage');

// Who can access this API?
exports.acl = ['special'];

// [...]

As you may have noticed, mage.auth.register receives and acl option allowing to attach to a give user different access rights. User commands can then in return list what ACL groups are allowed to acces that user command.

For instance, in the example above, a user registered only with the user credential would not be allowed to execute this user command. Only if the ‘user’ or ‘*’ wildcard ACL were added to the exports.acl array would a normal user be able to execute it.

By standard, user is assigned to any registered player, but you may create your own ACL groups as you see fit.

User command timeout

lib/modules/players/usercommands/register.js

var mage = require('mage');

// Who can access this API?
exports.acl = ['*'];

exports.timeout = 200

// [...]

By default, user command execution will time out after 15,000 milliseconds; however, in some cases, you may want to increase or reduce that value.

To do so, simply set exports.timeout to your desired value.

Keep in mind that the execution of your usercommand may not get interrupted; we will return an error on the next access to the user command’s state (which will in turn ensure that execution is interrupted), but manual operations unrelated to state may still complete.

Request caching

curl -X POST http://127.0.0.1:8080/game/players.checkStats?queryId=1 \
--data-binary @- << EOF
[{"key":"be20d767-4067-40d6-92dc-c52067b7d21e:lMftdnXxEFbP3ctq","name":"mage.session"}]
{}
EOF

 Invoke-RestMethod -Method Post -Uri "http://127.0.0.1:8080/game/players.checkStats?queryId=1" -Body '[{"key":"be20d767-4067-40d6-92dc-c52067b7d21e:lMftdnXxEFbP3ctq","name":"mage.session"}]
{}' | ConvertTo-Json

By default, responses to requests from authenticated users which contain a numerical identifier in the will be automatically cached; this is so to avoid double-execution when the client disconnects before the response could be sent and the client wishes to retry.

This comes handy for most operations (trades, purchases and so on), but may be undesirable in some circumstances (when you serve computed static data or static data stored in the database).

lib/modules/players/usercommands/checkStats.js

exports.cache = false;

To disable this behavior, simply set cache to false in your user command’s definition.

Using async/await (Node 7.6+)

lib/modules/players/index.js

'use strict';

const promisify = require('es6-promisify');
const {
  auth
} = require('mage');

exports.register = async function (state, username, password) {
  const options = {
    acl: ['user']
  };

  const register = promisify(auth.register, auth);

  return register(state, username, password, options);
};

lib/modules/players/usercommands/register.js

'use strict';

const {
  players
} = require('mage');

module.exports = {
  acl: ['*'],
  async execute(state, username, password) {
    return players.register(state, username, password);
  }
};

lib/modules/players/usercommands/staticData.js

'use strict';

module.exports = {
  serialize: false,
  acl: ['*'],
  async execute(state) {
    return '{"static": "data"}';
  }
};

If you are using a newer Node.js version, which includes the latest ES2015 and ES2017 language features, you can rewrite the previous API as follows. As you can see, this results not only in much fewer lines of code, but also into a much simpler, easier to read code.

Let’s review what we have done here:

  1. Variable declaration using const, which prohibits the variable to be rebound;
  2. Destructuring, to extract the specific MAGE modules and components we want to use;
  3. async/await and Promises, to simplify the expression of asynchronous code paths;

Note that due to legacy, most of MAGE’s API are callback-based, which can sometimes conflict with the latest Promise-based API’s; to help with this, we recommend that you install es6-promisify in your project, and then use it to wrap the different MAGE APIs you wish to use.

Also, you can see that the players.staticData user command serializes data by itself to JSON instead of relying on MAGE to serialize the return data. This can be useful when you wish to optimize how MAGE will serve certain pieces of data which will not change frequently. When you wish to do so, simply make sure that exports.serialize is set to false, and to manually return a stringified version of your data.

Error management

lib/modules/players/usercommands/register.js

'use strict';

const {
  players,
  MageError
} = require('mage');

class NoHomersError extends MageError {
  constructor(data) {
        super(data);

    // Code to return to the client (default: server)
    this.code = 'server';

    // Log level to use to log this error (default: error)
    this.level = 'warning';

    // Details to log alongside the message (default: undefined)
    this.details = data.details;

    // Error type - traditionally the class name
        this.type = 'NoHomersError';
    }
}

module.exports = {
  acl: ['*'],
  async execute(state, username, password) {
    if (username.length > 10) {
      // Using MageError directly
      throw new MageError({
        code: 'username_length_exceeded',
        level: 'warning',
        message: 'Username is more than 10 character',
        details: {
          received: username
        }
      })
    }

    if (username === 'homer') {
      // Using a custom error class inheriting MageError
      throw new NoHomersError({
        message: 'We already have one Homer anyway '
      })
    }

    return await players.register(state, username, password);
  }
};

When using async/await, you will want to customise the behavior of your errors in regards to how they will be logged, what data will be logged, what message will be returned to the user, and so on.

To do so, MAGE provides the MageError error class, which can be used as-is or extended as needed. This error class will allow you to control precisely what you will log in case of error, and what should be returned to the user.

States

You may notice that our user commands receive an object called state as part of the argument list.

Transaction management

States are used for tracking the state of a current user command execution. For instance, you will generally have to do a series of operations which, depending on the overall outcome of your user command execution, should all be stored (or all discarded if a failure occurs). States provide the mechanism for stacking operations which need to occur, and then commit them in one shot.

Transactional storage

lib/modules/players/usercommands/registerManyBroken.js

var mage = require('mage');

exports.acl = ['*'];

exports.execute = function (state, credentialsOne, credentialsTwo, callback) {
    mage.players.register(state, credentialsOne, function () {
    mage.players.register(state, credentialsTwo, function () {
            var error = new Error('Whoops this failed!');
            return state.error(error, error, callback);
        });
    });
};

In the example here, we basically error out on purpose, but the purpose is clear: we are trying to register two new users. However, because we end up calling state.error the actions will not be executed; the two mage.players.register calls we have made would only store information if the call succeded.

For more information about the API you use to access your data store, please read the Archivist API documentation.

Transactional event emission

lib/modules/players/usercommands/registerAndNotifyFriend.js

var mage = require('mage');

exports.acl = ['*'];

exports.execute = function (state, credentials, friendId, callback) {
    state.emit(friendId, 'friendJoined', credentials.username);

    mage.players.register(state, credentials, function (error) {
        if (error) {
            return state.error(error, error, callback);
        }

        callback();
    });
};

The state object is also responsible for emitting events for players. The event system is what enables the MAGE server and MAGE clients to stay synchronized, and is also the first-class communication interface to get players to send data between each others.

Events also benefit of the transactional nature of states; events to be sent to users will not be sent unless the call succeeds. For instance, in this example, if mage.players.register were to return an error, the event emitted by state.emit would never be sent to the other player referenced by playerId.

For more information on the State API and how events are emitted, please read the State API documentation.

Actors & Sessions

MAGE defines users as “actors”, who are represented by an ID (the Actor ID).

For an actor to make changes to the database (through a user command) and send events to other users, it will generally need to be authenticated. During authentication, an actor starts a session and is assigned a unique session ID.

As long as a session ID is used and reused by an actor, it will stay active. After a long period of non-activity however, the session will expire and the actor will be “logged out” as it were.

Session module

lib/index.js

mage.useModules([
  'session'
]);

Freshly bootstrapped MAGE applications already have the session module activated and configured (including a basic Archivist configuration which will store session-information in memory).

For multi-node MAGE clusters, make sure to change the vault used for sessions to be stored in a shared memory storage solution such as memcached, redis, etc… Since MAGE will need to retrieve sessions to route messages to them properly.

Auth module

Once configured you can just add the auth module to your useModules call. Please see built-in modules part to see how to set up the auth module.

Logging in

lib/modules/players/index.js

exports.login = function (state, username, password, callback) {
  mage.auth.login(state, username, password, callback);
};

lib/modules/players/usercommands/login.js

var mage = require('mage');
var logger = mage.logger.context('players');

exports.acl = ['*'];

// The API endpoint function
exports.execute = function (state, username, password, callback) {
  mage.players.login(state, username, password, function (error, session) {
    if (error) {
      return state.error(error.code, error, callback);
    }

    logger.debug('Logged in user:', session.actorId);
    callback();
  });
};

The auth module allows us to login. For now, let’s not bother with user accounts and use the anonymous login ability instead. As long as we do this as a developer (in development mode), we can login anonymously and get either user-level or even administrator-level privileges. In production that would be impossible, and running the same logic would result in “anonymous” privileges only. You wouldn’t be able to do much with that.

The session module will have automatically picked up the session ID that has been assigned to us, so there is nothing left for us to do.

When you are ready to create user accounts, please read on about how to use and configure the auth module.

Testing your login user command

curl -X POST http://127.0.0.1:8080/game/players.login \
--data-binary @- << EOF
[]
{"username": "test","password": "secret"}
EOF

 Invoke-RestMethod -Method Post -Uri "http://127.0.0.1:8080/game/players.login" -Body '[]
{"username": "test", "password": "secret"}' | ConvertTo-Json

If authentication fails, you will receive [["invalidUsernameOrPassword",null]]; otherwise, you should get back an event object containing your player’s session information.

Changing the password

You can change the password for a given user after registration. It works the same way as registration, except that the user ID needs to exist or you will get a UserNotFoundError. Note that this does not invalidate current sessions for this account.

lib/modules/players/index.js

exports.changePassword = function (state, username, newPassword, callback) {
  mage.auth.changePassword(state, username, newPassword, callback);
};

Archivist

Archivist is a key-value abstraction layer generally used with state objects.

The player module created through the previous sections already uses Archivist to store data on the local file system; more specifically, the auth module used in the Actors & Sessions section of this user guide uses Archivist behind the scenes to store credentials for newly created users.

Vaults

List, read and write order

./config/default.yaml

archivist:
    # When doing "list" operations, will attempt each mentioned vault until successful
    listOrder:
        - userVault
        - itemVault

    # When doing "get" operations, will attempt each mentioned vault until successful
    readOrder:
        - userVault
        - itemVault

    # When doing "add/set/touch/del" operations, will write to each mentioned vault in the given order
    writeOrder:
        - userVault
        - itemVault

listOrder, readOrder, and writeOrder properties have to be defined in your configuration file to specify the order when reading or writting data.
For read operations (listOrder, readOrder), mage will attempt the mentioned vaults until one is successful. However, for write operations (writeOrder), mage will write to each mentioned vault, in the given order.

The item won’t be written before the player because it will follow the order of the writeOrder configuration

state.archivist.set('item', { userId: userId }, playerData);
state.archivist.set('player', { itemId: itemId }, itemData);

Please note that if you are doing multiple operations in a single state transaction, the order in which the operations will be done correspond to the order provided by your configuration, not the order of the actual calls.

Vaults types

./config/default.yaml

archivist:
    vaults:
        userVault:
            type: file
            config:
                path: ./filevault/userVault
        itemVault:
            type: file
            config:
                path: ./filevault/itemVault

As mentioned, vaults are used by archivist to store data. Currently, the following backend targets are supported:

Backend Description
file Store data to the local disk, in JSON files.
memory Keep data in memory (does not persist).
client Special vault type (client-side archivist support required).
couchbase Couchbase interface
mysql MySQL interface.
redis Redis interface.

Vaults can have different configuration for different environments, as long as the Archivist API set used in your project is provided by the different vault backends you wish to use.

File vault backend

The file vault can be used to store data directly in your project. A ommon case for the use of the file vault backend is static data storage.

type: file
config:
    path: ./filevault
    disableExpiration: true  # optional (default: false)
operation supported implementation
list ✔ fs.readdir(config.path);
get ✔ fs.readFile('myfile.filevault' and 'myfile.json');
add ✔ fs.writeFile('myfile.filevault' and 'myfile.json');
set ✔ fs.writeFile('myfile.filevault' and 'myfile.json');
touch ✔ fs.readFile('myfile.filevault'); fs.writeFile('myfile.filevault');
del ✔ fs.readFile('myfile.filevault'); fs.unlink('myfile.filevault' and 'myfile.json');

archivist:create support is done via mkdirp and just requires that the user running the command has enough rights to create folders in the project’s path.

Memory

type: memory

The memory vault backend can be used to keep data in-memory for the duration of the execution of your MAGE instance. Data will not be persisted to disk.

operation supported implementation
list ✔ for (var trueName in cache) { }
get ✔ deserialize(cache[trueName(fullIndex, topic)])
add ✔ cache[trueName(fullIndex, topic)] = serialize(data)
set ✔ cache[trueName(fullIndex, topic)] = serialize(data)
touch ✔ setTimeout()
del ✔ delete cache[trueName(fullIndex, topic)]

Client

This vault is used to send updates to the player, so that their data is always synchronized in real time.

This vault is always created when an archivist is instantiated by a State object, using a name identical to the type: client.

This vault type requires no configuration.

operation supported implementation
list
get
add ✔ state.emitToActors('archivist:set')
set ✔ state.emitToActors('archivist:set' or 'archivist:applyDiff')
touch ✔ state.emitToActors('archivist:touch')
del ✔ state.emitToActors('archivist:del')

Couchbase

type: couchbase
config:
    options:
        # List of hosts in the cluster
        hosts: [ "localhost:8091" ]

        # Only for Couchbase Server >= 5.0
        # User credentials
        username: Administrator
        password: "password"

        # Only for Couchbase Server < 5.0
        # Bucket password (optional)
        password: "toto"

        # optional
        bucket: default

        # optional, useful if you share a bucket with other applications
        prefix: "bob/"

        # optional, can use any option specified in https://developer.couchbase.com/documentation/server/5.1/sdk/nodejs/client-settings.html#topic_pkk_vhn_qv__d397e189
        options:
          # usefull to debug network errors (eg. authentication errors)
          detailed_errcodes: 1

    # options only used with archivist:create
    create:
        adminUsername: admin
        adminPassword: "password"
        bucketType: couchbase # can be couchbase or memcached
        ramQuotaMB: 100       # how much memory to allocate to the bucket

For Couchbase Server >= 5.0, options.user and options.password have to be set to a user who has access to the options.bucket.

For Couchbase Server < 5.0, however, you just need to configure options.password which correspond to the bucket password and is optional.

create.adminUsername and create.password need to be configured only if you wish to create the underlying bucket through archivist:create, or to create views and query indexes through archivist:migrate.

operation supported implementation
list
get ✔ couchbase.get()
add ✔ couchbase.add()
set ✔ couchbase.set()
touch ✔ couchbase.touch()
del ✔ couchbase.remove()

archivist:create support requires a separate create entry in the config, meanwhile views should be created/managed in migration scripts.






MySQL

type: mysql
config:
    options:
        host: "myhost"
        user: "myuser"
        password: "mypassword"
        database: "mydb"

The available connection options are documented in the node-mysql readme. For pool options please look at Pool options.

operation supported implementation
list ✔ SELECT FROM table WHERE partialIndex
get ✔ SELECT FROM table WHERE fullIndex
add ✔ INSERT INTO table SET ?
set ✔ INSERT INTO table SET ? ON DUPLICATE KEY UPDATE ?
touch
del ✔ DELETE FROM table WHERE fullIndex

archivist:create support requires that the user is allowed to create databases.

Sample query to create a basic “people” topic table store.

CREATE TABLE people (
  personId INT UNSIGNED NOT NULL,
  value TEXT NOT NULL,
  mediaType VARCHAR(255) NOT NULL,
  PRIMARY KEY (personId)
);

Queries against your database are done through a combination of the generated keys and serialized values. A generated key must yield a table name and a primary key. A serialized value must yield a number of column names with their respective values.

For instance, given a topic people and index { personId: 1 }, the destination table will need to have a personId field, but also a value field to store data ad a mediaType field so that MAGE may know how to process the stored value.

Overriding the serializer

exports.people.vaults.mysql.serialize = function (value) {
    return {
        value: value.setEncoding(['utf8', 'buffer']).data,
        mediaType: value.mediaType,
        lastChanged: parseInt(Date.now() / 1000)
    };
};

If you want to change how this information is stored, by adding columns, etc, you can overload the serializer method to do so. For example, consider the following example if you want to add a timestamp to a lastChanged INT UNSIGNED NOT NULL column.

Redis

type: redis
config:
    port: 6379
    host: "127.0.0.1"
    options: {}
    prefix: "key/prefix/"

The options object is described in the node-redis readme. Both options and prefix are optional. The option return_buffers is turned on by default by the Archivist, because the default serialization will prepend values with meta data (in order to preserve mediaType awareness).

operation supported implementation
list
get ✔ redis.get()
add ✔ redis.set('NX')
set ✔ redis.set()
touch ✔ redis.expire()
del ✔ redis.del()

Topics

lib/archivist/index.js

exports.player = {
  index: ['userId'],
  vaults: {
    userVault: {}
  }
};

Topics are essentially Archivist datatypes; they define which vault(s) to use for storage, the key structure for accessing data, and so on.

In this example, we simply specify a new topic, called player, in which we will be identifying by userId.

Add an expiration time

In your topic config, you can specify a ttl to make your data expires after a certain amount of time.

ttl should be a string matching one of the following formats:

Add an expiration time

exports.player = {
  // ...
  ttl: '1m' // Expire the data after 1 minute
};

Store & retrieve topics

lib/modules/players/index.js

exports.create = function (state, userId, playerData) {
  state.archivist.set('player', { userId: userId }, playerData);
};

exports.list = function (state, callback) {
  var topic = 'player';
  var partialIndex = {};

  state.archivist.list(topic, partialIndex, function (error, indexes) {
    if (error) {
      return callback(error);
    }

    var queries = indexes.map(function (index) {
      return { topic: topic, index: index };
    });

    state.archivist.mget(queries, callback);
  });
};

lib/modules/players/usercommands/register.js

var mage = require('mage');
exports.acl = ['*'];
exports.execute = function (state, username, password, callback) {
  mage.players.register(state, username, password, function (error, userId) {
    if (error) {
      return state.error(error.code, error, callback);
    }

    mage.players.create(state, userId, {
      coins: 10,
      level: 1,
      tutorialCompleted: false
    });

    state.respond(userId);

    return callback();
  });
};

lib/modules/players/usercommands/list.js

var mage = require('mage')
exports.acl = ['*'];
exports.execute = function (state, callback) {
  mage.players.list(state, function (error, players) {
    // We ignore the error for brievety's sake
    state.respond(players);
    callback();
  });
};

Again, in this example we are leaving the ACL permissions entirely open so that you may try to manually access them; in the real world, however, you would need to make sure to put the right permissions in here.

In this example, we augment the players module we have previously created with two methods: create, and list. In each method, we use state.archivist to retrieve and store data. We then modify the players.register user command, and have it create the player’s data upon successful registration. Finally, we add a new user command called players.list, which will let us see a list of all players’ data.

You may notice that players.list actually calls two functions: state.archivist.list and state.archivist.mget; this is because list will return a list of indexes, which we then feed into mget (remember, Archivist works with key-value).

You may also notice that while state.archivist.list is asynchronous (it requires a callback function), state.archivist.set is not; because states act as transactions, writes are not executed against your backend storage until the transaction is completed, thus making write operations synchronous. This will generally be true of all state.archivist APIs; reads will be asynchronous, but writes will be synchronous.

Testing storage

curl -X POST http://127.0.0.1:8080/game/players.list \
--data-binary @- << EOF
[]
{}
EOF

 Invoke-RestMethod -Method Post -Uri "http://127.0.0.1:8080/game/players.list" -Body '[]
{}' | ConvertTo-Json

We can re-use the previous command to create a new user; once we have done so, we can use the following command to retrieve the data we have just created.

Key-based filtering

lib/archivist/index.js

exports.item = {
  index: ['userId', 'itemId'],
  vaults: {
    itemVault: {}
  }
};

lib/modules/items/index.js

exports.getItemsForUser = function (state, userId, callback) {
  var topic = 'item';
  var partialIndex = { userId: userId };

  state.archivist.scan(topic, partialIndex, callback);
};

With certain APIs you can provide only a portion of an index and search for all indexes who have the same value for that option. These indexes are referred to as partial indexes.

There are a few ways by which you can split and filter the data stored in your topics:

  1. You can use archivist.list to list all the indexes matching a given partial index
  2. You can use archivist.mget to fetch multiple indexes at once
  3. You can use archivist.scan, which combines both operations mentioned above into one

You will generally want to use scan for most of your operations, but in some cases, you will find that manually fetching the list of indexes using list and applying your own custom filtering before calling mget will give you a better result.

Limiting access

lib/archivist/index.js

exports.item = {
  index: ['userId', 'itemId'],
  vaults: {
    client: {
      shard: function (value) {
        return value.index.userId;
      },
      acl: function (test) {
        test(['user', 'test'], 'get', { shard: true });
        test(['cms', 'admin'], '*');
      }
    },
    inventoryVault: {}
  }
};

In most cases, you will want to make sure that a given user will only be able to access data they have the permission to access.

There are primarily two ways to limit access to topics:

In this example, we use the shard function to limit returned data to only data which matches the userId.

We then use the acl function to only allow users and tests access to the get API, but full access to CMS users and administrators.

Database Creation

Some vaults also support database/vault creation via the archivist:create command as long as admin credentials are properly configured, see each vault’s configuration on how to use it.

List of archivist:create enabled backends:

It is not recommended to use those features in production.

Migrations

MAGE supports database migration scripts similar to Ruby on Rails 2.1 which are aligned with your package.json version and exposed via the archivist:migrate command.

Running the archivist:migrate command will go through each migrations in order up to the current package.json version and apply them. The command also allows specifying an exact version allowing for testing new migrations or reverting to a previous version.

How to write migration scripts

Migration scripts are single files per vault and per version. These files are JavaScript modules and should export two methods: up and down, to allow migration in two directions. You are strongly encouraged to implement a down migration path, but if it’s really impossible, you may leave out the down method. Keep in mind that this will block rollback operations. See the sample on the right side for more details.

exports.up = function (vault, cb) {
        var sql =
                'CREATE TABLE inventory (\n' +
                '  actorId VARCHAR(255) NOT NULL PRIMARY KEY,\n' +
                '  value TEXT NOT NULL,\n' +
                '  mediaType VARCHAR(255) NOT NULL\n' +
                ') ENGINE=InnoDB';

        vault.pool.query(sql, null, function (error) {
                if (error) {
                        return cb(error);
                }

                return cb(null, { summary: 'Created the inventory table' });
        });
};

exports.down = function (vault, cb) {
        vault.pool.query('DROP TABLE inventory', null, cb);
};

The migration file goes to your game’s lib/archivist/migrations folder into a subfolder per vault. This folder should have the exact same name as your vault does. The migration file you provide should be named after the version in package.json and have the extension .{js,ts}. Other file extensions are ignored.

Some typical examples:

The callback of the up method allows you to pass a report, that will be stored with the migration itself inside the version history. In MySQL for example, this is all stored in a schema_migrations table, which is automatically created.

How to execute migrations

Migrations can be executed by calling some specific CLI commands, which are detailed when you run npm run help or mage --help. They allow you to create a database, drop a database, and run migrations. This is what they look like:

archivist:create [vaults]     create database environments for all configured vaults
archivist:drop [vaults]       destroy database environments for all configured vaults
archivist:migrate [version]   migrates all vaults to the current version, or to the version requested

Maximum data size (warning and errors)

archivist:
  size:
    # Default set to 1Mb (1024 kilobytes); set to false to disable
    warning: 256

    # Disabled by default
    error: 512

MAGE will keep track of all data that is written into vaults, and automatically log a warning when the data size reaches a certain threshold. Optionally, you can also configure MAGE to throw an error should the data reach a certain size.

You may configure this behavior by configuring archivist.size.warning and archivist.size.error in your configuration files. By default, MAGE will never throw an error no matter how big your data gets, but will log a warning should your data be bigger than 1 megabyte.

Events

We have seen in the States section of this user guide that states can be used to emit events between players. Before explaining how to send events, we will first see how MAGE send events to the clients, and how to configure the server to do so.

How does it work ?

Events sending and receipt is done via Message Stream.

Message Stream is a protocol used by MAGE servers and its clients in order to communicate. This protocol is implemented through different transports, which are the following:

If you need more information about Message Stream protocol, you can read this documentation.

In your MAGE config file, you can specify the priority of the transports which will be used by the client SDK to receive the events.

config/default.yaml

server:
    msgStream:
        detect:
            - websocket
            - longpolling
            - shortpolling

You can also configure longpolling transport:

config/default.yaml

server:
    msgStream:
        transports:
            longpolling:
                heartbeat: 60

For the longpolling transport, you can specify a heartbeat config, which correspond to the number of seconds until a request expire and automatically close.

Now we have seen how to configure your server to send and receive events, we will now see how to send events with the State object.

Sending events

lib/modules/players/usercommands/annoy.js

exports.acl = ['*'];
exports.execute = function (state, actorId, payload, callback) {
  state.emit(actorId, 'annoy', payload);
  callback();
};

When a user command is executed, you can stack many events to be emitted once the user command succeeds. Those events will then be sent synchronously to the destination.

Sending asynchronous events

lib/modules/players/usercommands/bombard.js

var State = require('mage').core.State;
exports.acl = ['*'];
exports.execute = function (state, actorId, payload, callback) {
  var asynchronousState = new State();
  var count = 0

  function schedule() {
    setTimeout(function () {
        asynchronousState.emit(actorId, 'annoy', payload);
        count += 1;

        if (count === 100) {
            return asynchronousState.close()
        }

        schedule();
    }, 1000);
  }

  schedule();
  callback();
};

In some cases, you might want to emit events not attached to a user command. For instance, you may want to send an event after a certain amount of time, or once something has changed in the database. To do so, you will need to create your own State of that. You will also need to make sure to manually close that state.

For more information, please read the State API documentation.

Broadcasting events

lib/modules/players/usercommands/annoyEveryone.js

exports.acl = ['*'];
exports.execute = function (state, payload, callback) {
    state.broadcast('annoy', payload);
    callback();
};

In some rare case, you might want to emit events to all users. For instance, you might want to warn connected users of an upcoming maintenance, or of other events which might affect them.

In such cases, you will want to use state.broadcast to send the event to everyone. Keep in mind that broadcasting to all may affect your overall load if you have many players connected simultaneously.

Time manipulation

lib/modules/myModule/index.js

const {
  time,
  logger
} = require('mage')

// Accelerate time by a factor of 5
time.bend(0, 5)

exports.method = function (state) {
  const now = time.sec();

  if (now > lastLogin + (60 * 60 * 24)) {
    // do daily login bonus
  }

  state.archivist.set('someTopic', { userId: state.actorId }, {
    time: now
  });
}

Some types of games are meant to be played over fixed period of time; some game features may also be time-sensitive. For instance, you might want to give daily bonuses on player log in.

However, during testing, you probably do not want to wait for a whole day to see if your player will be awarded a bonus. To deal with this issue, you can use the MAGE built-in mage.time module. This module allows developer to slow down or accelerate time from the MAGE process’ perspective.

This feature is often refered to as time bending

Note that this does not affect existing APIs (such as setTimeout, setInterval, or the Date class); instead, you will need to use the the time module to compute a time value from the server’s perspective, then use that value as a setTimeout/setInterval/new Date call argument.

For more information on how to use the time library, see the time module API documentation. You may also want to have a look at the following libraries whenever dealing with time and time bending:

Logging

Logging is an important part of running production-ready game servers. MAGE ships with its own logging API, which developers can use and configure in different ways depending on the environment they are running the server on.

Log levels (channels)

var mage = require('mage');
var logger = mage.logger;
logger.debug('hello world');
logger.info.data({
  debug: 'data'
}).log('trying to do something');

logger.error('It broke', new Error('this error stack will be parsed and formatted'));

Log channels define the level of priority and importance of a log entry. Just like in most systems, the level of verbosity of a MAGE server can be configured; during development, you will probably want to show debug logs, while in production seeing warnings and errors will be sufficient.

The following channels are provided in MAGE

Channel Description
verbose Low-level debug information (I/O details, etc); reserved to MAGE internals
debug Game server debugging information
info User command request information
notice Services state change notification (example: third-party services and databases)
warning An unusual situation occurred, which requires analysis
error A user request caused an error. The user should still be able to continue using the services
critical A user is now stuck in a broken state which the system cannot naturally repair
alert Internal services (data store API calls failed, etc) or external services are failing
emergency The app cannot boot or stopped unexpectedly

Log contexts

lib/modules/players/index.js

var mage = require('mage');
exports.logger = mage.logger.context('players');

lib/modules/players/usercommands/log.js

var mage = require('mage');
var logger = mage.players.logger.context('log');

exports.acl = ['*']

exports.execute = function (state, callback) {
    logger.debug('This log is very contextualized');
    callback();
};

Log output

w-12345 - 23:59:59.999    <debug> [gameName players log] This log is very contextualized

In addition to the channel, you may want to set a logger context to help you sort out log output. Developers are free to use contexts as they see fit.

In this example, we first attach the players context to the logger that will be used at the module level, and then expose it; then, in a user command, we add an additional context specific to the user command, and use the resulting logger to simply log a message.

In the terminal, you would then see the following log output. Notice that the context is now appended to the terminal output.

Log backends

The following logging backends are provided:

type Description
terminal Log to the console
file Log to local files
syslog Log to syslog through UDP
graylog Log to GELF

Terminal

Disable terminal logging

logging:
    server:
        terminal: false

Terminal config example

logging:
    server:
        terminal:
            channels: [">=info"]
            config:
                jsonIndent: 2
                jsonOutput: false
                theme: default

The terminal log backend can be configured for pretty-logging, which makes reading log entries in your console more visually comfortable.

The following themes are available:

The terminal log backend may also be configured for piping logs to an external process. For instance, you may be deploying your MAGE in PaaS or IaaS which simply forwards and parses stdout/stderr output.

In such case, you can turn the jsonOutput configuration entry to true; each log line outputed will then be outputed as a JSON object.

File

File config example

logging:
    server:
        file:
            channels: [">=debug"]
            config:
                path: "./logs"
                jsonIndent: 2
                mode: "0600"    # make sure this is a string!
                fileNames:
                    "app.log": "all"    # this is configured by default and you may override it
                    "error.log": ">=warning"

The file log backend allows you to output logs to a set of file of your choice. Simply specify a log directory where you want your log files to go, and a set of filenames to log to. You can control which log level will go in which file by setting the log level range as a value, or specify all if you wish to write all logs to a single file.









Syslog

Syslog config example

logging:
    server:
        syslog:
            channels: [">=debug"]
            config:
                host: localhost          # host to connect to (IP or hostname)
                port: 514                # UDP port to connect to
                appName: myGame
                facility: 1              # see syslog documentation
                format:
                    multiLine: true      # allow newline characters
                    indent: 2            # indentation when serializing data in multiLine mode

The syslog log backend allows you to forward your logs to a remote syslog server using the UDP protocol.

MAGE does not currently support forwarding to syslog TCP servers; because of this, it also does not support using TLS.

Since only UDP is supported, it also means that some logs may not arrive to destination.









Graylog

Graylog config example

logging:
    server:
        graylog:
            channels: [">=info"]
            config:
                servers:
                    - { host: "192.168.100.85", port: 12201 }
                facility: Application identifier
                format:
                    multiLine: true      # allow newline characters
                    embedDetails: false  # embed log details into the message
                    embedData: false     # embed data into the message

The syslog log backend allows you to forward your logs to a remote graylog2 server, or to any other services capable to consuming the GELF protocol.

Such services include:

You may choose to embed details and data into the message, instead of having them as separate attributes. If so, respectively turn embedDetails and embedData to true.

HTTP Server

You might end up in a case where you would like to do one of the following:

  1. Serve files from your MAGE server (useful when developing HTML5 games)
  2. Serve service status files (or content)
  3. Proxy requests to a remote server through MAGE

To this end, MAGE provides to developers an API that will allow you to do such things.

Cross-Origin Resource Sharing (CORS)

If you want your application to span multiple domains, you need to enable CORS. For information on what CORS is, please consult the following websites.

Performance

Keep in mind that using CORS will often cause so-called “preflight” requests. A preflight request is an HTTP OPTIONS request to the server to confirm if a request is allowed to be made in a manner that is considered safe for the user. Only after this confirmation will a real GET or POST request be made. All this happens invisible to the end user and developer, but there is a performance penalty that you pay, caused by this extra round trip to the server.

Using authentication and CORS

If you use Basic or any other HTTP authentication mechanism, you cannot configure CORS to allow any origin using the * wildcard symbol. In that case, you must specify exactly which origin is allowed to access your server.

Configuration

In your configuration, you can enable CORS like this:

server:
    clientHost:
        cors:
            methods: "GET, POST, OPTIONS"
            origin: "http://mage-app.wizcorp.jp"
            credentials: true

Log Configuration

server:
    quietRoutes: # Filter out debug and verbose logs for URLs matching these regex
        - ^\/check\.txt
        - ^\/favicon\.ico
    longRoutes: # Filter out long warnings for U##### What does it change for other browsers?

Absolutely nothing. And you can still apply the retry logic on network errors, it's not a bad idea.RLs matching these regex
        - ^\/msgstream
    longThreshold: 500 # The number of milliseconds before a request is considered to be taking too long

The following logs will be filtered out when the url for the request matches any regex in the quietRoutes:

m-28019 - 19:58:44.830     <debug> [MAGE http] Received HTTP GET request: /check.txt
m-28019 - 19:58:44.830   <verbose> [MAGE http] Following HTTP route /check.txt

The following log will be shown for any http request that takes longer than the configured longThreshold and can be filtered out when the url for the request matches any reges in the longRoutes:

m-876 - 20:08:58.193   <warning> [MAGE http] /app/pc/landing completed in 1181 msec

Clustering

At some point during development, you will want to start looking into deploying multiple instances of your game servers; once you do, you will need to change your configuration to tell MAGE instances:

  1. How they can find each others (through service discovery);
  2. How they can connect to each others (through MAGE’s Message Relay Protocol, or MMRP).

This section will cover how you can configure these two services for different development and production use-cases.

Cluster identification

server:
    serviceName: applicationName-environmentID

Currently the message server system will identify itself as being a part of a cluster by using the application root package name and version. However in environment where multiple instances of the same application and version are run, there will be conflicts with the messaging system. (e.g. inside single box which houses multiple test environments).

To prevent pollution and contamination of messages, the server.serviceName configuration entry needs to be set, to give each environment a unique identifier.

Service discovery

server:
    serviceDiscovery: false

Service discovery takes care of letting each MAGE servers where they can find the other servers.

Engine Description
single In-memory discovery service (useful during development)
mdns Bonjour/MDNS-based service discovery
zookeeper ZooKeeper-based service discovery
consul Consul-based service discovery

By default, service discovery is disabled. To enable it, you will need to specify what engine you wish to use, and what configuration you wish to use for that engine.

Single

server:
    serviceDiscovery:
        engine: single

The single engine can be used during development to locally allow the use of the service discovery API. It will only find the local server.



Bonjour/MDNS

server:
    serviceDiscovery:
        engine: mdns
        options:
            # Provide a unique identifier. You will need to configure
            # this when you have multiple instances of your game cluster
            # running on the same network, so to avoid MAGE servers from one
            # cluster from connecting to your cluster.
            description: "UniqueIdOnTheNetwork"

The MDNS engine will use MDNS broadcasts to let all MAGE servers on a given network when new servers appear or disappear.

This engine is very convenient, since it allows for service discovery without having to configure any additonal services. However, note that certain network (such as the ones provided by AWS) wil not allow broadcasts, and so you will not be able to use this engine in such case.





ZooKeeper

server:
    serviceDiscovery:
        engine: zookeeper
        options:
            # The interface to announce the IP for. By default, all
            # IP are announced
            interface: eth0

            # List of available ZooKeeper nodes (comma-separated)
            hosts: "192.168.1.12:2181,192.168.3.18:2181"

            # Additional options to pass to the client library.
            # See https://github.com/alexguan/node-zookeeper-client#client-createclientconnectionstring-options
            # for more details
            options:
                sessionTimeout: 30000

The zookeeper engine will use ZooKeeper to announce MAGE servers.













Consul

server:
    serviceDiscovery:
        engine: consul
        options:
            # Interface to announce
            interface: enp4s0

            # optional
            consul:
                host: consul.service.dc.consul

The consul engine will use Consul to announce MAGE servers.

MAGE Message Relay Protocol (MMRP)

server:
    mmrp:
        bind:
            host: "*"  # asterisk for 0.0.0.0, or a valid IP address
            port: "*"  # asterisk for any port, or a valid integer
        network:
            - "192.168.2"  # formatted according to https://www.npmjs.com/package/netmask

MMRP (MAGE Message Relay Protocol) is the messaging layer between node instances. It is used to enable communication between multiple MAGE instances and between the different node processes run by MAGE. In the end, it allows messages to flow from one user to another.

MMRP depends on service discovery to announce relays on the network to each process. The protocol and library used to communicate between processes is ZeroMQ.

Metrics

MAGE exposes different metrics out of the box.

Configuration

config/default.yaml

sampler:
    sampleMage: false
    intervals:
        metrics: 1000 # Sampling time window, in milliseconds

There are essentially two configuration elements which you can set in your configuration:

Depending on your needs, you may wish to configure multiple endpoints, but in many cases, one will suffice.

Accessing metrics

Query sampler

curl http://localhost:8080/savvy/sampler/metrics

 Invoke-RestMethod -Method Get -Uri "http://localhost:8080/savvy/sampler/metrics" | ConvertTo-Json

Response

{
  "id": 0,
  "name": "metrics",
  "interval": 1,
  "data": {}
}

Unless you turn sampleMage to true (and you really should!), the amount of data that will be returned will be minimal.

However, when turning sampleMage on, you will be able to see things such as number of state errors, mean latency per user command, and so on.

Adding custom metrics

lib/modules/players/usercommands/countClicks.js

var mage = require('mage');
var sampler = mage.core.sampler;

exports.acl = ['*']

exports.execute = function (state, callback) {
    sampler.inc(['players', 'clicks'], 'count', 1);
    callback();
};

Trigger clicks

curl -X POST http://127.0.0.1:8080/game/players.countClicks \
--data-binary @- << EOF
[]
{}
EOF

 Invoke-RestMethod -Method Post -Uri "http://127.0.0.1:8080/game/players.countClicks" -Body '[]
{}' | ConvertTo-Json

New sampler output

[...]
  "data": {
    "players": {
      "clicks": {
        "count": {
          "type": "inc",
          "values": {
            "1": {
              "val": 4,
              "timeStamp": 1491400000000
[...]

Here we can see a full example of how we can create our own custom metrics and then access them.

Sampler values are defined on-the-fly; therefore, you must be careful when choosing a sampler key for your metrics, so to avoid overlaps.

See the sampler API documentation for more documentation.

Production

In a production environment, you should set NODE_ENV to production and provide MAGE with a configuration file called config/production.yaml or config/production.json.

developmentMode

The developmentMode entry MUST be turned off. You may also choose to run the game with an environment variable which explicitly turns it off, just in case the configuration went wrong, by running it like this:

DEVELOPMENT_MODE=false npm start

&{ $env:DEVELOPMENT_MODE="false"; npm start }

server

The “server” entry in the configuration must be set up properly. That probably means:

shell powershell