General purpose backend library. The primary goal is to have a scalable platform for running and managing Node.js servers for Web services implementation.
This project only covers the lower portion of the Web services ecosystem: Node.js processes, HTTP servers, basic API functionality, database access, caching, messaging between processes, metrics and monitoring, a library of tools for developing Node.js servers.
For the UI and presentation layer there are no restrictions what to use as long as it can run on top of the Express server.
Features:
Check out the Documentation for more details.
To install the module with all optional dependencies if they are available in the system
npm install backendjs
To install from the git
npm install git+https://github.com/vseryakov/backendjs.git
or simply
npm install vseryakov/backendjs
Only core required dependencies are installed but there are many modules which require a module to work correctly.
All optional dependencies are listed in the package.json under "modDependencies" so npm cannot use it, only manual install of required modules is supported or it is possible to install all optional dependencies for development purposes.
Here is the list of modules required for each internal feature:
pg - PostgreSQL database accessargon2 or bcrypt - for user password hashingmmmagic - file detection in uploads, only used when allow is passed to the api.putFileconsolidate - for API templating, disabled by defaultredis - for Redis queue and cache driverunix-dgram - for syslog on Linux to use local syslogbkjs-sqlite - to use SQLite database driverweb-push - for Web push notifications@parse/node-apn - for Apple push notificationsbkjs-wand - for scaling images in uploads using ImageMagick modulesharp - scaling images in uploads using VPS imagingnats - NATS driver for queue and eventsamqplib - RabbitMQ driver for queue and events (alpha)The command below will show all core and optional dependencies, npm install will install only the core dependencies
bkjs deps -dry-run -mods
Simplest way of using the backendjs, it will start the server listening on port 8000
$ node
> const bkjs = require('backendjs')
> bkjs.server.start()
Access is allowed only with valid signature except urls that are explicitly allowed without it (see api-allow config parameter below)
Same but using the helper tool, by default no database driver are enablked so here we use embedded SQLite database and listen on port 8000.
bkjs web -db-pool sqlite -db-sqlite-pool default
or to the PostgreSQL server, database backend (if not running local server can be started with bkjs init-pgsql if postgresql is installed)
bkjs web -db-pool pg -db-pg-pool postgresql://postgres@localhost/backend
If running on EC2 instance with IAM profile no need to specify AWS credentials:
bkjs web -db-pool dynamodb -db-dynamodb-pool default
To start the server and connect to the DynamoDB (command line parameters can be saved in the etc/config file, see below about config files)
bkjs web -db-pool dynamodb -db-dynamodb-pool default -aws-key XXXX -aws-secret XXXX
or to the ElasticSearch server, database backend
bkjs web -db-pool elasticsearch -db-elasticsearch-pool http://127.0.0.1:9200
All commands above will behave exactly the same
Tables are not created by default, in order to initialize the database, run the server or the shell with -db-create-tables flag,
it is called only inside a master process, a worker never creates tables on start
prepare the tables in the shell
bksh -db-pool dynamodb -db-dynamodb-pool default -db-create-tables
run the server and create tables on start, run Elasticsearch locally first on the local machine
bkjs get-elasticsearch
bkjs run-elasticsearch
bkjs web -db-pool elasticsearch -db-elasticsearch-pool http://127.0.0.1:9200 -db-create-tables
While the local backendjs is runnning, the documentation is always available at http://localhost:8000/doc.html (or whatever port is the server using)
To add users from the command line
bksh -user-add login test secret test name TestUser email test@test.com
To start Node.js shell with backendjs loaded and initialized, all command line parameters apply to the shell as well
bkjs shell
To access the database while in the shell using callbacks
> db.select("bk_user", {}, lib.log);
> db.add("bk_user", { id: 'test2', login: 'test2', secret: 'test2', name' Test 2 name' }, lib.log);
> db.select("bk_user", { id: 'test2' }, lib.log);
> db.select("bk_user", { id: ['test1','test2'] }, { ops: { id: "in" } }, lib.log);
or the same using async/await, same methods with a prepended to the name
> await db.aselect("bk_user", {});
> await db.aadd("bk_user", { id: 'test2', login: 'test2', secret: 'test2', name' Test 2 name' });
> await db.aselect("bk_user", { id: 'test2' });
To search using Elasticsearch (assuming it runs on EC2 and it is synced with DynamoDB using streams)
> await db.select("bk_user", { q: 'test' }, { pool: "elasticsearch" });
The library is packaged with copies of Bootstrap, jQuery, Knockout.js for quick Web development in web/js and web/css directories, all scripts are available from the browser with /js or /css paths. To use all at once as a bundle run the following command:
cd node_modules/backendjs && npm run devbuild
Go to examples/api directory:
Run the application, it will start the Web server on port 8000:
./app.sh
Now log in with the new account,
Go to http://localhost:8000/api.html and click on Login at the top-right corner, then enter 'test' as login and 'test' as secret in the login popup dialog.
To see your account details run the command in the console /account/get
To see current metrics run the command in the console /system/stats/get
When the web server is started with -watch parameter or as bkjs watch then any change in the source files will make the server restart automatically
letting you focus on the source code and not server management, this mode is only enabled by default in development mode,
check app.sh for parameters before running it in production.
Almost everything in the backend is configurable using config files, a config database or DNS. The whole principle behind it is that once deployed in production, even quick restarts are impossible to do so there should be a way to push config changes to the processes without restarting.
Every module defines a set of config parameters that defines the behavior of the code, due to the single threaded nature of the Node.js. It is simple to update any config parameter to a new value so the code can operate differently. To achieve this the code must be written in a special way, like driven by configuration which can be changed at any time.
All configuration goes through the configuration process that checks all inputs and produces valid output which is applied to the module variables. Config file or database table with configuration can be loaded on demand or periodically, for example all local config files are watched for modification and reloaded automatically, the config database is loaded periodically which is defined by another config parameter.
When the backendjs server starts it spawns several processes that perform different tasks.
There are 2 major tasks of the backend that can be run at the same time or in any combination:
These features can be run standalone or under the guard of the monitor which tracks all running processes and restarted any failed ones.
This is the typical output from the ps command on Linux server:
ec2-user 891 0.0 0.6 1071632 49504 ? Ssl 14:33 0:01 bkjs: monitor
ec2-user 899 0.0 0.6 1073844 52892 ? Sl 14:33 0:01 bkjs: master
ec2-user 908 0.0 0.8 1081020 68780 ? Sl 14:33 0:02 bkjs: server
ec2-user 917 0.0 0.7 1072820 59008 ? Sl 14:33 0:01 bkjs: web
ec2-user 919 0.0 0.7 1072820 60792 ? Sl 14:33 0:02 bkjs: web
ec2-user 921 0.0 0.7 1072120 40721 ? Sl 14:33 0:02 bkjs: worker
To enable any task a command line parameter must be provided, it cannot be specified in the config file. The bkjs utility supports several
commands that simplify running the backend in different modes.
bkjs watch - runs the master and Web server in wather mode checking all source files for changes, this is the common command to be used
in development, it passes the command line switches: -watch -masterbkjs start - this command is supposed to be run at the server startup as a service, it runs in the background and the monitors all tasks,
the env variable BKJS_SERVER can be set in the profile to one of the master or monitor to define which run mode to use, default mode is monitorbkjs monitor - this command is supposed to be run at the server startup, it runs in the background and the monitors all processes,
the command line parameters are: -daemon -monitor -master -syslogbkjs master - this command is supposed to be run at the server startup, it runs in the background and the monitors all processes,
the command line parameters are: -daemon -monitor -master -syslog, web server and workers are started by defaultbkjs web - this command runs just web server process with child processes as web workersbkjs run - this command runs without other parameters, all additional parameters can be added in the command line, this command
is a barebone helper to be used with any other custom settings.bkjs run -api - this command runs a single process as web server, sutable for Dockerbkjs run -worker - this command runs a single process worker, suatable for Dockerbkjs shell or bksh - start backendjs shell, no API or Web server is initialized, only the database poolsThe main purpose of the backendjs is to provide API to access the data, the data can be stored in the database or some other way but the access to that data will be over HTTP and returned back as JSON. This is default functionality but any custom application may return data in whatever format is required.
Basically the backendjs is a Web server with ability to perform data processing using local or remote jobs which can be scheduled similar to Unix cron.
The principle behind the system is that nowadays the API services just return data which Web apps or mobiles apps can render to the user without the backend involved. It does not mean this is simple gateway between the database, in many cases it is but if special processing of the data is needed before sending it to the user, it is possible to do and backendjs provides many convenient helpers and tools for it.
When the API layer is initialized, the api module contains app object which is an Express server.
Special module/namespace app is designated to be used for application development/extension. This module is available in the same way as api and core
which makes it easy to refer and extend with additional methods and structures.
The typical structure of a single file backendjs application is the following:
const bkjs = require('backendjs');
const api = bkjs.api;
const app = bkjs.app;
const db = bkjs.db;
app.listArg = [];
// Define the module config parameters
core.describeArgs('app', [
{ name: "list-arg", array: 1, type: "list", descr: "List of words" },
{ name: "int-arg", type: "int", descr: "An integer parameter" },
]);
// Describe the tables or data models, all DB pools will use it, the master or shell
// process only creates new tables, workers just use the existing tables
db.describeTables({
...
});
// Optionally customize the Express environment, setup MVC routes or else, `api.app` is the Express server
app.configureMiddleware = function(options, callback)
{
...
callback()
}
// Register API endpoints, i.e. url callbacks
app.configureWeb = function(options, callback)
{
api.app.get('/some/api/endpoint', (req, res) => {
// to return an error, the message will be translated with internal i18n module if locales
// are loaded and the request requires it
api.sendReply(res, err);
// or with custom status and message, explicitely translated
api.sendReply(res, 404, res.__({ phrase: "not found", locale: "fr" }));
// with config check
if (app.intArg > 5) ...
if (app.listArg.indexOf(req.query.name) > -1) ...
// to send data back with optional postprocessing hooks
api.sendJSON(req, err, data);
// or simply
res.json(data);
});
...
callback();
}
// Optionally register post processing of the returned data from the default calls
api.registerPostProcess('', /^\/account\/([a-z\/]+)$/, (req, res, rows) => { ... });
...
// Optionally register access permissions callbacks
api.registerAccessCheck('', /^\/test\/list$/, (req, status, callback) => { ... });
api.registerPreProcess('', /^\/test\/list$/, (req, status, callback) => { ... });
...
bkjs.server.start();
Another probably easier way to create single file apps is to use your namespace instead of app:
const bkjs = require("backendjs");
const api = bkjs.api;
const db = bkjs.db;
const mymod = {
name: "mymod",
args: [
{ name: "types", type: "list", descr: "Types allowed" },
{ name: "size", type: "int", descr: "Records in one page" },
],
tables: {
mytable: {
id: { type: "int", primary: 1 },
name: { primary: 2 },
type: { type: "list" },
descr: {}
}
}
};
exports.module = mymod;
bkjs.core.addModule(mymod);
mymod.configureWeb = function(options, callback)
{
api.app.all("/mymod", async function(req, res) {
if (!req.query.id) return api.sendReply(res, 400, "id is required");
req.query.type = mod.types;
const rows = await db.aselect("mymod", req.query, { ops: { type: "in" }, count: mod.size });
api.sendJSON(req, null, rows);
});
}
bkjs.server.start();
Except the app.configureWeb and server.start() all other functions are optional, they are here for the sake of completeness of the example. Also
because running the backend involves more than just running web server many things can be setup using the configuration options like common access permissions,
configuration of the cron jobs so the amount of code to be written to have fully functioning production API server is not that much, basically only
request endpoint callbacks must be provided in the application.
As with any Node.js application, node modules are the way to build and extend the functionality, backendjs does not restrict how the application is structured.
By default no system modules are loaded except bk_user, it must be configured by the -preload-modules config parameter to
preload modules from the backendjs/modules/.
Another way to add functionality to the backend is via external modules specific to the backend, these modules are loaded on startup from the backend
home subdirectory modules/. The format is the same as for regular Node.js modules and only top level .js files are loaded on the backend startup.
Once loaded they have the same access to the backend as the rest of the code, the only difference is that they reside in the backend home and
can be shipped regardless of the npm, node modules and other env setup. These modules are exposed in the core.modules the same way as all other core submodules
methods.
Let's assume the modules/ contains file facebook.js which implements custom FB logic:
const bkjs = require("backendjs");
const core = bkjs.core;
const mod = {
name: "facebook",
args: [
{ name: "token", descr: "API token" },
]
}
module.exports = mod;
mod.configureWeb = function(options, callback) {
...
}
mod.makeRequest = function(options, callback) {
core.sendRequest({ url: options.path, query: { access_token: fb.token } }, callback);
}
This is the main app code:
const bkjs = require("backendjs");
const core = bkjs.core;
// Using facebook module in the main app
api.app.get("/me", (req, res) => {
core.modules.facebook.makeRequest({ path: "/me" }, (err, data) => {
bkjs.api.sendJSON(req, err, data);
});
});
bkj.server.start();
In case different modules is better keep separately for maintenance or development purposes they can be split into
separate NPM packages, the structure is the same, modules must be in the modules/ folder and the package must be loadable
via require as usual. In most cases just empty index.js is enough. Such modules will not be loaded via require though but
by the backendjs core.loadModule machinery, the NPM packages are just keep different module directories separate from each other.
The config parameter allow-packages can be used to specify NPM package names to be loaded separated by comma, as with the default
application structure all subfolders inside each NPM package will be added to the core:
If there is a config file present as etc/config it will be loaded as well, this way each package can maintain its default config parameters if necessary
without touching other or global configuration. Although such config files will not be reloaded on changes, when NPM installs or updates packages it
moves files around so watching the old config is no point because the updated config file will be different.
The backend support multiple databases and provides the same db layer for access. Common operations are supported and all other specific usage can be achieved by
using SQL directly or other query language supported by any particular database.
The database operations supported in the unified way provide simple actions like db.get, db.put, db.update, db.del, db.select. The db.query method provides generic
access to the database driver and executes given query directly by the db driver, it can be SQL or other driver specific query request.
Before the tables can be queried the schema must be defined and created, the backend db layer provides simple functions to do it:
db.describeTables({
album: {
id: { primary: 1 }, // Primary key for an album
name: { pub: 1 }, // Album name, public column
mtime: { type: "now" }, // Modification timestamp
},
photo: {
album_id: { primary: 1 }, // Combined primary key
id: { primary: 1 }, // consisting of album and photo id
name: { pub: 1, index: 1 }, // Photo name or description, public column with the index for faster search
mtime: { type: "now" }
}
});
Each database may restrict how the schema is defined and used, the db layer does not provide an artificial layer hiding all specifics, it just provides the same API and syntax, for example, DynamoDB tables must have only hash primary key or combined hash and range key, so when creating table to be used with DynamoDB, only one or two columns can be marked with primary property while for SQL databases the composite primary key can consist of more than 2 columns.
The backendjs always creates several tables in the configured database pools by default, these tables are required to support default API functionality and some
are required for backend operations. Refer below for the JavaScript modules documentation that described which tables are created by default. In the custom applications
the db.describeTables method can modify columns in the default table and add more columns if needed.
For example, to make age and some other columns in the accounts table public and visible by other users with additional columns the following can be
done in the api.initApplication method. It will extend the bk_user table and the application can use new columns the same way as the already existing columns.
Using the birthday column we make 'age' property automatically calculated and visible in the result, this is done by the internal method api.processAccountRow which
is registered as post process callback for the bk_user table. The computed property age will be returned because it is not present in the table definition
and all properties not defined and configured are passed as is.
The cleanup of the public columns is done by the api.sendJSON which is used by all API routes when ready to send data back to the client. If any post-process
hooks are registered and return data itself then it is the hook responsibility to cleanup non-public columns.
db.describeTables({
bk_user: {
birthday: {},
ssn: {},
salary: { type: "int" },
occupation: {},
home_phone: {},
work_phone: {},
});
app.configureWeb = function(options, callback)
{
db.setProcessRow("post", "bk_user", this.processAccountRow);
...
callback();
}
app.processAccountRow = function(req, row, options)
{
if (row.birthday) row.age = Math.floor((Date.now() - core.toDate(row.birthday))/(86400000*365));
}
To define tables inside a module just provide a tables property in the module object, it will be picked up by database initialization automatically.
const mod = {
name: "billing",
tables: {
invoices: {
id: { type: "int", primary: 1 },
name: {},
price: { type: "real" },
mtime: { type: "now" }
}
}
}
module.exports = mod;
// Run db setup once all the DB pools are configured, for example produce dynamic icon property
// for each record retrieved
mod.configureModule = function(options, callback)
{
db.setProcessRows("post", "invoices", function(req, row, opts) {
if (row.id) row.icon = "/images/" + row.id + ".png";
});
callback();
}
This is useful for easier naming conventions or switching to a different table name on the fly without changinbf the code, access to the table by it is real name is always available.
For example:
bksh -db-aliases-bk_user users
> await db.aget("bk_user", { login: "u1" })
> { login: "u1", name: "user", .... }
> await db.aget("users", { login: "u1" })
> { login: "u1", name: "user", .... }
All methods will put input parameters in the req.query, GET or POST.
One way to verify input values is to use lib.toParams, only specified parameters will be returned and converted according to
the type or ignored.
Example:
var params = {
test1: { id: { type: "text" },
count: { type: "int" },
email: { regexp: /^[^@]+@[^@]+$/ }
}
};
api.app.all("/endpoint/test1", function(req, res) {
const query = lib.toParams(req.query, params.test1);
if (typeof query == "string") return api.sendReply(res, 400, query);
...
});
Here is an example how to create simple TODO application using any database supported by the backend. It supports basic operations like add/update/delete a record, show all records.
Create a file named app.js with the code below.
const bkjs = require('backendjs');
const api = bkjs.api;
const lib = bkjs.lib;
const app = bkjs.app;
const db = bkjs.db;
// Describe the table to store todo records
db.describeTables({
todo: {
id: { type: "uuid", primary: 1 }, // Store unique task id
due: {}, // Due date
name: {}, // Short task name
descr: {}, // Full description
mtime: { type: "now" } // Last update time in ms
}
});
// API routes
app.configureWeb = function(options, callback)
{
api.app.get(/^\/todo\/([a-z]+)$/, async function(req, res) {
var options = api.getOptions(req);
switch (req.params[0]) {
case "get":
if (!req.query.id) return api.sendReply(res, 400, "id is required");
const rows = await db.aget("todo", { id: req.query.id }, options);
api.sendJSON(req, null, rows);
break;
case "select":
options.noscan = 0; // Allow empty scan of the whole table if no query is given, disabled by default
const rows = await db.aselect("todo", req.query, options);
api.sendJSON(req, null, rows);
break;
case "add":
if (!req.query.name) return api.sendReply(res, 400, "name is required");
// By default due date is tomorrow
if (req.query.due) req.query.due = lib.toDate(req.query.due, Date.now() + 86400000).toISOString();
db.add("todo", req.query, options, (err, rows) => {
api.sendJSON(req, err, rows);
});
break;
case "update":
if (!req.query.id) return api.sendReply(res, 400, "id is required");
const rows = await db.aupdate("todo", req.query, options);
api.sendJSON(req, null, rows);
break;
case "del":
if (!req.query.id) return api.sendReply(res, 400, "id is required");
db.del("todo", { id: req.query.id }, options, (err, rows) => {
api.sendJSON(req, err, rows);
});
break;
}
});
callback();
}
bkjs.server.start();
Now run it with an option to allow API access without an account:
node app.js -log debug -web -api-allow-path /todo -db-create-tables
To use a different database, for example PostgresSQL(running localy) or DynamoDB(assuming EC2 instance), all config parametetrs can be stored in the etc/config as well
node app.js -log debug -web -api-allow-path /todo -db-pool dynamodb -db-dynamodb-pool default -db-create-tables
node app.js -log debug -web -api-allow-path /todo -db-pool pg -db-pg-pool default -db-create-tables
API commands can be executed in the browser or using curl:
curl 'http://localhost:8000/todo?name=TestTask1&descr=Descr1&due=2015-01-01`
curl 'http://localhost:8000/todo/select'
When the backend server starts and no -home argument passed in the command line the backend makes its home environment in the ~/.bkjs directory.
It is also possible to set the default home using BKJS_HOME environment variable.
The backend directory structure is the following:
etc - configuration directory, all config files are there
etc/profile - shell script loaded by the bkjs utility to customize env variables
etc/config - config parameters, same as specified in the command line but without leading -, each config parameter per line:
Example:
debug=1
db-pool=dynamodb
db-dynamodb-pool=http://localhost:9000
db-pg-pool=postgresql://postgres@127.0.0.1/backend
To specify other config file: bkjs shell -config-file file
etc/config.local - same as the config but for the cases when local environment is different than the production or for dev specific parameters
on startup the following local config files will be loaded if present: etc/config.runMode and etc/config.instance.tag. These will be loaded after the main config but before config.local. The runMode is set to development by default and can be changed with -run-mode config parameter, the instance tag is set with -instance-tag config parameter.
etc/crontab - jobs to be run with intervals, JSON file with a list of cron jobs objects:
Example:
Create file in ~/.backend/etc/crontab with the following contents:
[ { "cron": "0 1 1 * * 1,3", "job": { "app.cleanSessions": { "interval": 3600000 } } } ]
Define the function that the cron will call with the options specified, callback must be called at the end, create this app.js file
var bkjs = require("backendjs");
bkjs.app.cleanSessions = function(options, callback) {
bkjs.db.delAll("session", { mtime: options.interval + Date.now() }, { ops: "le" }, callback);
}
bkjs.server.start()
Start the jobs queue and the web server at once
bkjs master -jobs-workers 1 -jobs-cron
etc/crontab.local - additional local crontab that is read after the main one, for local or dev environment
run-mode and db-pool config parameters can be configured in DNS as TXT records, the backend on startup will try to resolve such records and use the value if not empty.
All params that marked with DNS TXT can be configured in the DNS server for the domain where the backend is running, the config parameter name is
concatenated with the domain and queried for the TXT record, for example: run-mode parameter will be queried for run-mode.domain.name for TXT record type.
modules - loadable modules with specific functionality
images - all images to be served by the API server, every subfolder represent naming space with lots of subfolders for images
var - database files created by the server
tmp - temporary files
web - Web pages served by the static Express middleware
Database layer support caching of the responses using db.getCached call, it retrieves exactly one record from the configured cache, if no record exists it
will pull it from the database and on success will store it in the cache before returning to the client. When dealing with cached records, there is a special option
that must be passed to all put/update/del database methods in order to clear local cache, so next time the record will be retrieved with new changes from the database
and refresh the cache, that is { cached: true } can be passed in the options parameter for the db methods that may modify records with cached contents. In any case
it is required to clear cache manually there is db.clearCache method for that.
Also there is a configuration option -db-caching to make any table automatically cached for all requests.
If no cache is configured the local driver is used, it keeps the cache on the master process in the LRU pool and any worker or Web process
communicate with it via internal messaging provided by the cluster module. This works only for a single server.
Set ipc-client=redis://HOST[:PORT] that points to the server running Redis server.
The config option max_attempts defines maximum number of times to reconnect before giving up. Any other node-redis module parameter can be passed as well in
the options or url, the system supports special parameters that start with bk-, it will extract them into options automatically.
For example:
ipc-client=redis://host1?bk-max_attempts=3
ipc-client-backup=redis://host2
ipc-client-backup-options-max_attempts=3
If configured all processes subscribe to it and listen for system messages, it must support PUB/SUB and does not need to be reliable. Websockets in the API server also use the system bus to send broadcasts between multiple api instances.
ipc-client-system=redis://
ipc-system-queue=system
To configure the backend to use Redis for job processing set ipc-queue=redis://HOST where HOST is IP address or hostname of the single Redis server.
This driver implements reliable Redis queue, with visibilityTimeout config option works similar to AWS SQS.
Once configured, then all calls to jobs.submitJob will push jobs to be executed to the Redis queue, starting somewhere a backend master
process with -jobs-workers 2 will launch 2 worker processes which will start pulling jobs from the queue and execute.
The naming convention is that any function defined as function(options, callback) can be used as a job to be executed in one of the worker processes.
An example of how to perform jobs in the API routes:
core.describeArgs('app', [
{ name: "queue", descr: "Queue for jobs" },
]);
app.queue = "somequeue";
app.processAccounts = function(options, callback) {
db.select("bk_user", { type: options.type || "user" }, (err, rows) => {
...
callback();
});
}
api.all("/process/accounts", function(req, res) {
jobs.submitJob({ job: { "app.processAccounts": { type: req.query.type } } }, { queueName: app.queue }, (err) => {
api.sendReply(res, err);
});
});
To use AWS SQS for job processing set ipc-queue=https://sqs.amazonaws.com...., this queue system will poll SQS for new messages on a worker
and after successful execution will delete the message. For long running jobs it will automatically extend visibility timeout if it is configured.
The local queue is implemented on the master process as a list, communication is done via local sockets between the master and workers. This is intended for a single server development purposes only.
To use NATS (https://nats.io) configure a queue like ipc-queue-nats=nats://HOST:PORT, it supports broadcasts and job queues only, visibility timeout is supported as well.
To configure the backend to use RabbitMQ for messaging set ipc-queue=amqp://HOST and optionally amqp-options=JSON with options to the amqp module.
Additional objects from the config JSON are used for specific AMQP functions: { queueParams: {}, subscribeParams: {}, publishParams: {} }. These
will be passed to the corresponding AMQP methods: amqp.queue, amqp.queue.subcribe, amqp.publish. See AMQP Node.js module for more info.
This is default setup of the backend when all API requests except must provide valid signature and all HTML, JavaScript, CSS and image files
are available to everyone. This mode assumes that Web development will be based on 'single-page' design when only data is requested from the Web server and all
rendering is done using JavaScript. This is how the examples/api/api.html developers console is implemented, using JQuery-UI and Knockout.js.
To see current default config parameters run any of the following commands:
bkjs bkhelp | grep api-allow
node -e 'require("backendjs").core.showHelp()'
This is a mode when the whole Web site is secure by default, even access to the HTML files must be authenticated. In this mode the pages must defined 'Backend.session = true' during the initialization on every html page, it will enable Web sessions for the site and then no need to sign every API request.
The typical client JavaScript verification for the html page may look like this, it will redirect to login page if needed, this assumes the default path '/public' still allowed without the signature:
<link href="/css/bkjs.bundle.css" rel="stylesheet">
<script src="/js/bkjs.bundle.js" type="text/javascript"></script>
<script>
$(function () {
bkjs.session = true;
$(bkjs).on("bkjs.nologin", function() { window.location='/public/index.html'; });
bkjs.koInit();
});
</script>
On the backend side in your application app.js it needs more secure settings defined i.e. no html except /public will be accessible and
in case of error will be redirected to the login page by the server. Note, in the login page bkjs.session must be set to true for all
html pages to work after login without singing every API request.
app.configureMiddleware = function(options, callback) {
this.allow.splice(this.allow.indexOf('^/$'), 1);
this.allow.splice(this.allow.indexOf('\\.html$'), 1);
callback();
}
api.registerPreProcess('', /^\/$|\.html$/, function(req, status, callback) {
if (status.status != 200) {
status.status = 302;
status.url = '/public/index.html';
}
callback(status);
});
The simplest way is to configure ws-port to the same value as the HTTP port. This will run WebSockets server along the regular Web server.
In the browser the connection config is stored in the bkjs.wsconf and by default it connects to the local server on port 8000.
There are two ways to send messages via Websockets to the server from a browser:
as urls, eg. bkjs.wsSend('/project/update?id=1&name=Test2')
In this case the url will be parsed and checked for access and authorization before letting it pass via Express routes. This method allows to share the same route handlers between HTTP and Websockets requests, the handlers will use the same code and all responses will be sent back, only in the Websockets case the response will arrived in the message listener (see an example below)
bkjs.wsConnect({ path: "/project/ws?id=1" });
$(bkjs).on("bkjs.ws.message", (msg) => {
switch (msg.op) {
case "/account/update":
bkjs.wsSend("/account/ws/account");
break;
case "/project/update":
for (const p in msg.project) app.project[p] = msg.project[p];
break;
case "/message/new":
bkjs.showAlert("info", `New message: ${msg.msg}`);
break;
}
});
as JSON objects, eg. bkjs.wsSend({ op: "/project/update", project: { id: 1, name: "Test2" } })
In this case the server still have to check for access so it treats all JSON messages as coming from the path which was used during the connect,
i.e. the one stored in the bkjs.wsconf.path. The Express route handler for this path will receive all messages from Websocket clients, the response will be
received in the event listener the same way as for the first use case.
// Notify all clients who is using the project being updated
api.app.all("/project/ws", (req, res) => {
switch (req.query.op) {
case "/project/update":
// some code ....
api.wsNotify({ query: { id: req.query.project.id } }, { op: "/project/update", project: req.query.project });
break;
}
res.send("");
});
In any case all Websocket messages sent from the server will arrive in the event handler and must be formatted properly in order to distinguish what is what, this is
the application logic. If the server needs to send a message to all or some specific clients for example due to some updates in the DB, it must use the
api.wsNotify function.
// Received a new message for a user from external API service, notify all websocket clients by account id
api.app.post("/api/message", (req, res) => {
....
... processing logic
....
api.wsNotify({ account_id: req.query.uid }, { op: "/message/new", msg: req.query.msg });
});
There is no ready to use support for different versions of API because there is no just one solution that satisfies all applications. But there are tools ready to use that will allow to implement such versioning system in the backend. Some examples are provided below:
Fixed versions
This is similar to AWS version system when versions are fixed and changed not very often. A client can specify the core version
using bk-version header. When a request is parsed and the version is provided it will be set in the request options object as apiVersion.
All API routes are defined using Express middleware and one of the possible ways of dealing with different versions can look like this, by appending version to the command it is very simple to call only changed API code.
api.all(/\/domain\/(get|put|del)/, function(req, res) {
var options = api.getOptions(req);
var cmd = req.params[0];
if (options.apiVersion) cmd += "/" + options.apiVersion;
switch (cmd) {
case "get":
break;
case "get/2015-01-01":
break;
case "put":
break;
case "put/2015-02-01":
break;
case "del"
break;
}
});
Application semver support For cases when applications support Semver kind of versioning and it may be too many releases the method above still can be used while the number of versions is small, once too many different versions with different minor/patch numbers, it is easier to support greater/less comparisons.
The application version bk-app can be supplied in the query or as a header or in the user-agent HTTP header which is the easiest case for mobile apps.
In the middlware, the code can look like this:
var options = api.getOptions(req);
var version = lib.toVersion(options.appVersion);
switch (req.params[0]) {
case "get":
if (version < lib.toVersion("1.2.5")) {
res.json({ id: 1, name: "name", description: "descr" });
break;
}
if (version < lib.toVersion("1.1")) {
res.json([id, name]);
break;
}
res.json({ id: 1, name: "name", descr: "descr" });
break;
}
The actual implementation can be modularized, split into functions, controllers.... there are no restrictions how to build the working backend code, the backend just provides all necessary information for the middleware modules.
The purpose of the bkjs shell script is to act as a helper tool in configuring and managing the backend environment
and as well to be used in operations on production systems. It is not required for the backend operations and provided as a convenience tool
which is used in the backend development and can be useful for others running or testing the backend.
Running without arguments will bring help screen with description of all available commands.
The tool is multi-command utility where the first argument is the command to be executed with optional additional arguments if needed. On Linux, when started the bkjs tries to load and source the following config files:
/etc/default/bkjs
/etc/sysconfig/bkjs
$BKJS_HOME/etc/profile
Any of the following config files can redefine any environment variable thus pointing to the correct backend environment directory or customize the running environment, these should be regular shell scripts using bash syntax.
Most common used commands are:
bkjs watch - run the backend or the app for development purposes, uses local app.js if exists otherwise runs generic server
bkjs shell - start REPL shell with the backend module loaded and available for use, all submodules are available in the shell as well like core, db, api
bkjs sync [-path path] [-host host] [-user user] - sync sources of the app with the remote site, this is for development version of the backend only
bkjs init-server [-home path] [-user user] [-host name] [-domain name] - initialize Linux instance(Amazon) for backend use, optional -home can be specified where the backend home will be instead of ~/.bkjs, optional -user tells to use existing user instead of the current user and not root.
This command will create /etc/sysconfig/bkjs file with BKJS_HOME set to the home of the
backendjs app which was passed in the command line. This makes the bkjs or bksh run globally regardless of the current directory.
Then run the dev build script to produce web/js/bkjs.bundle.js and web/css/bkjs.bundle.css
cd node_modules/backendjs && npm run devbuild
Now instead of including a bunch of .js or css files in the html pages it only needs /js/bkjs.bundle.js and /css/bkjs.bundle.css. The configuration is in the package.json file.
The list of files to be used in bundles is in the package.json under config.bundles.
To enable auto bundler in your project just add to the local config ~/.bkjs/etc/config.local a list of directories to be
watched for changes. For example adding these lines to the local config will enable the watcher and bundle support
watch-web=web/js,web/css,$HOME/src/js,$HOME/src/css
watch-ignore=.bundle.(js|css)$
build-web=bkjs web-bundle -dev
The simple script below allows to build the bundle and refresh Chrome tab automatically, saves several clicks:
#!/bin/bash
bkjs web-bundle -dev -file $2
[ "$?" != "0" ] && exit
osascript -e "tell application \"Google Chrome\" to reload (tabs of window 1 whose URL contains \"$1\")"
To use it call this script instead in the config.local:
build-web=web-bundle.sh /website
NOTE: Because the rebuild happens while the watcher is running there are cases like the server is restarting or pulling a large update from the repository when the bundle build may not be called or called too early. To force rebuild run the command:
bkjs web-bundle -dev -all -force
start new AWS instance via AWS console, use Amazon Linux
login as ec2-user
install commands
git clone https://github.com/vseryakov/backendjs.git
sudo backendjs/bkjs install-ec2 -tools $(pwd)/backendjs/tools
run ps agx, it should show several backend processes running after monit started the service
try to access the instance via HTTP port for the API console or documentation
NOTE: if running behind a Load balancer and actual IP address is needed set Express option in the command line -api-express-options {"trust%20proxy":1}. In the config file
replacing spaces with %20 is not required.
Note: on OS X laptop the -aws-sdk-profile uc when AWS credentials are in the ~/.aws/credentials.
On the running machine which will be used for an image:
bksh -aws-create-image -no-reboot
Use an instance by tag for an image:
bksh -aws-create-image -no-reboot -instance-id `bkjs ec2-show -tag api -fmt id | head -1`
When launching from an EC2 instance no need to specify any AWS credentials.
admin (EC2)
bksh -aws-sdk-profile uc -aws-launch-instances -aws-instance-type t2.small -subnet-name api -name admin -elb-name Admin -alarm-name alarms -public-ip 1 -dry-run
api (EC2)
bksh -aws-sdk-profile uc -aws-launch-instances -aws-instance-type m3.large -subnet-name api -name api -elb-name api -alarm-name alarms -public-ip 1 -dry-run
jobs (EC2)
bksh -aws-sdk-profile uc -aws-launch-instances -aws-instance-type t2.small -subnet-name internal -name sync -alarm-name alarms -dry-run
bksh -aws-sdk-profile uc -aws-launch-instances -aws-instance-type t2.small -subnet-name internal -name sync -zone 1c -alarm-name alarms -dry-run
Elasticsearch
bksh -aws-sdk-profile uc -aws-launch-instances -aws-instance-type m3.large -subnet-name internal -name elasticsearch -bkjs-cmd stop-service -bkjs-cmd "init-elasticsearch-service -memsize 50" -alarm-name alarms -public-ip 1 -dry-run
Redis
bksh -aws-sdk-profile uc -aws-launch-instances -aws-instance-type m3.large -subnet-name internal -name redis -bkjs-cmd stop-service -bkjs-cmd "init-redis-service -memsize 70" -alarm-name alarms -public-ip 1 -dry-run
bksh -aws-create-launch-template-version -name jobs -aws-sdk-profile uc -dry-run
bksh -aws-create-launch-template-version -name api -aws-sdk-profile uc -dry-run
bksh -aws-set-route53 -name elasticsearch.ec-internal -filter elasticsearch
By default the Web proceses spawned by the server are load balanced using default cluster module which relies on the OS to do scheduling. On Linux with node 0.10 this is proven not to work properly due to the kernel keeping the context switches to a minimum thus resulting in one process to be very busy while the others idle. Node versions 4 and above perform round-robin by default.
For such case the Backendjs implements the proxy mode by setting proxy-port config parameter to any number above 1000, this will be the initial
port for the web processes to listen for incoming requests, for example if use -proxy-port 3000 and launch 2 web processes they will listen on ports
3000 and 3001. The main server process will start internal HTTP proxy and will perform round-robin load balancing the incoming requests between the web processes by forwarding
them to the web processes over TCP and then returning the responses back to the clients.
The first thing when deploying the backend into production is to change API HTTP port, by default is is 8000, but we would want port 80 so regardless how the environment is setup it is ultimately 2 ways to specify the port for HTTP server to use:
config file
The config file is always located in the etc/ folder in the backend home directory, how the home is specified depends on the system but basically it can be
defined via command line arguments as -home or via environment variables when using bkjs. See bkjs documentation but on AWS instances created with bkjs
init-server command, for non-standard home use /etc/sysconfig/bkjs profile, specify BKJS_HOME=/home/backend there and the rest will be taken care of
command line arguments
When running node scripts which use the backend, just specify -home command line argument with the directory where your backend should be and the backend will use it
Example:
node app.js -home $HOME -port 80
config database
If -db-config is specified in the command line or db-config= in the local config file, this will trigger loading additional
config parameters from the specified database pool, it will load all records from the bk_config table on that db pool. Using the database to store
configuration make it easier to maintain dynamic environment for example in case of auto scaling or launching on demand, this way
a new instance will query current config from the database and this eliminates supporting text files and distributing them to all instances.
The config database is refreshed from time to time acording to the db-config-interval parameter, also all records with ttl property in the bk_config
will be pulled every ttl interval and updated in place.
DNS records
Some config options may be kept in the DNS TXT records and every time a instance is started it will query the local DNS for such parameters. Only a small subset of
all config parameters support DNS store. To see which parameters can be stored in the DNS run bkjs show-help and look for 'DNS TXT configurable'.
git clone https://github.com/vseryakov/backendjs.git or git clone git@github.com:vseryakov/backendjs.git
cd backendjs
if Node.js is already installed skip to the next section
to install binary release run the command, it will install it into /opt/local on Darwin
bkjs install-node
bkjs install-node -prefix /usr/local/node
Important: Add NODE_PATH=$BKJS_PREFIX/lib/node_modules to your environment in .profile or .bash_profile so node can find global modules, replace $BKJS_PREFIX with the actual path unless this variable is also set in the .profile
to install all dependencies and make backendjs module and bkjs globally available:
npm link backendjs
to run local server on port 8000 run command:
bkjs web
to start the backend in command line mode, the backend environment is prepared and initialized including all database pools. This command line access allows you to test and run all functions from all modules of the backend without running full server similar to Node.js REPL functionality. All modules are accessible from the command line.
$ ./bkjs shell
> core.version
'0.70.0'
> logger.setLevel('info')
While creating Backendjs there were many questions and issues to be considered, some I was able to implement, some still not. Below are the thoughts that might be useful when designing, developing or choosing the API platform:
All API endpoints are optional and can be disabled or replaced easily. By default the naming convention is:
/namespace/command[/subname[/subcommand]]
Any HTTP methods can be used because its the command in the URL that defines the operation. The payload can be url-encoded query parameters or JSON or any other format supported by any particular endpoint. This makes the backend universal and usable with any environment, not just a Web browser. Request signature can be passed in the query so it does not require HTTP headers at all.
All requests to the API server must be signed with account login/secret pair.
The resulting signature is sent as HTTP header bk-signature or in the header specified by the api-signature-name config parameter.
For JSON content type, the method must be POST and no query parameters specified, instead everything should be inside the JSON object which is placed in the body of the request. For additional safety, SHA1 checksum of the JSON payload can be calculated and passed in the signature, this is the only way to ensure the body is not modified when not using query parameters.
See web/js/bkjs.js function bkjs.createSignature or
api.js function api.createSignature for the JavaScript implementations.
There is also native iOS implementation Bkjs.m.
/auth
This API request returns the current user record from the bk_user table if the request is verified and the signature provided
is valid. If no signature or it is invalid the result will be an error with the corresponding error code and message.
By default this endpoint is secured, i.e. requires a valid signature.
Parameters:
_session=1 - if the call is authenticated a cookie with the session signature is returned, from now on
all requests with such cookie will be authenticated, the primary use for this is Web apps/login
Same as the /auth but it uses secret for user authentication, this request does not need a signature, just simple login and secret query parameters to be sent to the backend. This must be sent over SSL.
Parameters:
login - account loginsecret - account secret_session=1 - same as in /auth requestOn successful login, the result contains full account record including the secret, this is the only time when the secret is returned back
Example:
$.ajax({ url: "/login?login=test123&secret=test123&_session=1",
success: function(json, status, xhr) { console.log(json) }
});
> { id: "XXXX...", name: "Test User", login: "test123", ...}
/logout
Logout the current user, clear session cookies if exist. For pure API access with the signature this will not do anything on the backend side.
The accounts API manages accounts and authentication, it provides basic user account features with common fields like email, name, address.
/account/get
Returns information about the current account, all account columns are returned except the secret and other table columns with the property priv
Response:
{ "id": "57d07a4e28fc4f33bdca9f6c8e04d6c3",
"name": "Test User",
"mtime": 1391824028,
"login": "testuser",
"type": ["user"],
}
How to make an account as admin
# Run backend shell
bkjs shell
# Update record by login
> db.update("bk_user", { login: 'login@name', type: 'admin' });
/account/update
Update current account with new values, the parameters are columns of the table bk_user, only columns with non empty values will be updated.
Example:
/account/update?name=New%2BName
When running with AWS load balancer there should be a url that a load balancer polls all the time and this must be very quick and lightweight request. For this
purpose there is an API endpoint /ping that just responds with status 200. It is open by default in the default api-allow-path config parameter.
The data API is a generic way to access any table in the database with common operations, as oppose to the any specific APIs above this API only deals with one table and one record without maintaining any other features like auto counters, cache...
Because it exposes the whole database to anybody who has a login it is a good idea to disable this endpoint in the production or provide access callback that verifies who can access it.
To disable this endpoint completely in the config: deny-modules=bk_data
To allow admins to access it only in the config: api-allow-admin=^/data
To allow admins to access it only:
api.registerPreProcess('GET', '/data', function(req, status, cb) { if (req.account.type != "admin") return cb({ status: 401, message: 'access denied' }; cb(status)); });
This is implemented by the data module from the core.
/data/columns
/data/columns/TABLE
Return columns for all tables or the specific TABLE
/data/keys/TABLE
Return primary keys for the given TABLE
/data/(select|search|list|get|add|put|update|del|incr|replace)/TABLE
Perform database operation on the given TABLE, all options for the db functiobns are passed as query parametrrs prepended with underscore,
regular parameters are the table columns.
By default the API does not allow table scans without a condition to avoid expensive and long queries, to enable a scan pass _noscan=0.
For this to work the Data API must be configured as unsecure in the config file using the parameter api-unsecure=data.
Some tables like messages and connections perform data convertion before returning the results, mostly splitting combined columns like type into
separate fields. To return raw data pass the parameter _noprocessrows=1.
Example:
/data/get/bk_user?login=12345
/data/update/bk_user?login=12345&name=Admin
/data/select/bk_user?name=john&_ops=name,gt&_select=name,email
/data/select/bk_user?_noscan=0&_noprocessrows=1
The system API returns information about the backend statistics, allows provisioning and configuration commands and other internal maintenance functions. By default is is open for access to all users but same security considerations apply here as for the Data API.
This is implemented by the system module from the core. To enable this functionality specify -preload-modules=bk_system.
/system/restart
Perform restart of the Web processes, this will be done gracefully, only one Web worker process will be restarting while the other processes will keep
serving requests. The intention is to allow code updates on live systems without service interruption.
/system/cache/(init|stats|keys|get|set|put|incr|del|clear)
Access to the caching functions
/system/config/(init)
Access to the config functions
/system/msg/(init|send)
Access to the messaging functions
/system/jobs/(send)
Access to the jobs functions
/system/queue/(init|publish)
Access to the queue functions
/system/params/get
Return all config parameters applied from the config file(s) or remote database.
/system/stats/get
Database pool statistics and other diagnostics
Individual sub-objects:
Vlad Seryakov
Check out the Documentation for more details.
FAQs
A platform for building backends
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