Proxy utility to bundle a batch of calls in one request. Using the batchelor utility reduces HTTP overhead, network round-trip delay time and helps to keep your API design clean.

• Features
• Installation
• API
  • configure(options)
    • Example options
  • execute(batch, callback)
    • request
    • Example batches
      • Single request
      • Array of requests
  • stop(options)
  • Events
• Examples
  • REST using ExpressJS Version 4.5.x
  • WebSocket - Server
  • Request - WebSocket Client - sending 3 types of requests
  • Response from previous request

Features

• Server side parallel request processing.
• Persistent request for Web Socket facade.

Installation

npm install batchelorjs --save

API

configure(options)

configure the batchelor object.

• log - a logger object containing debug,info and error function (default: empty logger).
• transport - a transport object implementing issueCalls function (default: internal transport using async and request).
• maxConcurrentBatches - maximum concurrent batch requests (default:50)
• whiteList - an array containing a list of allowed hosts for processing the request (default: *, meaning allow all host/urls).
• request - Object containing the default values per request

Example options

{
    maxConcurrentBatches: 100,
    logger: console,
    request: {
        "method": "GET",
        "timeout": 10000,
        "ip": "unknown",
        "headers": {},
        "strictSSL" : true,
        "pool": {
            "maxSockets": 200
        }
    }
    whiteList: ["*"]
}

execute(batch, callback)

• batch - A single request object (see below) or an array of single requests [required]
• callback(err, results) - A callback function to notify the batch processing has finished [required]
  The callback function gets 2 arguments:
  • err - error object, if an error occur, null otherwise
  • results - an JSON object containing the result/s of the batch

request

An object representing a single request in the batch, in the form:

• name - identifier of the item, the name is used as reference. Names must be UNIQUE! [required]
• url - URL that calls the item. Possible GET parameters are also given here [required]
• method - possible values are GET or POST or whatever methods the called API supports [required]
• encoding - the encoding of the item (default:UTF8) [optional]
• retries - number of retries if the timeout is reach (default:2) [optional]
• headers - the headers that the item uses [optional]
• body || data - the parameters that the item uses when the method is POST are given here [optional]
• timeout - number of milliseconds to wait for a request from the API to respond before aborting the request, if this parameters is not provided we use timeout from the config.json file [optional]
• isOnCloseRequest - flag indicating if the item should be called when the connection is droped, used when using web socket facade (default:false) [optional]
• persistent - flag indicating if the item should be called in persistent way, used when using web socket facade(default:false) [optional]
• persistentDelay - number of delay between persistent items in milliseconds, used when using web socket facade (default:5000) [optional]

Example batches

Single request

{
	"name": "REQUEST_1",
	"method": "GET",
	"url": "jsonresponser.herokuapp.com/api/json/users",
	"timeout": 1000
}

Array of requests

[
	{
		"name": "REQUEST_1",
		"method": "GET",
		"url": "jsonresponser.herokuapp.com/api/json/users",
		"timeout": 1000
	}
	, 
	{
		"name": "REQUEST_2",
		"method": "POST",
		"url": "jsonresponser.herokuapp.com/api/json/users",
		"timeout": 1000
	}
]

stop(options)

• options - an object containing the ids to be stopped, the ids provided on persistent requests [required]

    options = {
        ids: ["id1", "id2"] || "id1"
    }
  

returns an array of the requests stopped (empty if not found).

Events

EventEmitter API - will emit the following events:

• processing with batchId data
• complete with batchId data
• persistent_processed with uniqueId data
• persistent_stopped with uniqueId data

Examples

REST using ExpressJS Version 4.5.x

var exp_app = express();
var compression = require('compression');
var bodyParser = require('body-parser');
var exp_router = express.Router();
exp_app.use(compression());
exp_app.use(bodyParser());
var batchelor = require('batchelorjs');
var configuration = {
    "maxConcurrentBatches": 100,
    "logger": console,
    "request": {
        "method": "GET",
        "timeout": 10000,
        "ip": "unknown",
        "headers": {},
        "data": ""
    },
    "whiteList": ["*"]
};


batchelor.configure(configuration);
exp_router.post("/", function (req, res, next) {
    batchelor.execute(req.body, function (err, results) {
        if (err) {
            console.log("Error occur");
        }
        else {
            res.send(JSON.stringify(results));
        }
    });
});

exp_app.use("/", exp_router);
exp_app.listen(5050);

WebSocket - Server

var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({port: 5050});
var batchelor = require('batchelorjs');
var configuration = {
    "maxConcurrentBatches": 100,
    "logger": console,
    "request": {
        "method": "GET",
        "timeout": 10000,
        "ip": "unknown",
        "headers": {},
        "data": ""
    },
    "whiteList": ["*"]
};

batchelor.persistent.configure(configuration);
ws.on("message", function (data) {
    batchelor.persistent.execute(data,
        function (err, results) {
            ws.send(JSON.stringify(results));
        });
});

Request - WebSocket Client - sending 3 types of requests

The following example will send 3 types of requests; regular, persistent, and on-close. Batchelor will process these requests and return a response when:

• regular: a response is returned from the given URL
• persistent: every persistentDelay milliseconds, if there is a change in the response
• on-close: once the connection is dropped from client

var batch = [
	{
        name: "regular_request",
        url: "jsonresponser.herokuapp.com/api/json/users"
        method: "GET",
        timeout: 5000, 
    },
    {
        name: "persistent_request",
        url: "jsonresponser.herokuapp.com/api/json/users"
        method: "GET",
        timeout: 5000, 
        persistent: true
        persistentDelay: 5000
    },
    {
        name: "onclose_request",
        url: "https://www.domain.com/item/2"
        method: "POST",
        retries: 5,
        timeout: 5000,
        isOnCloseRequest: true
    }
];
var ws = new WebSocket("wss://yourdomain/path");
ws.onopen = function (ws) {
    document.getElementById("connectionStatus").innerHTML = "Connected";
    ws.send(JSON.stringify(batch));
};
ws.onmessage = function (event) {
    document.getElementById("responseFromServer").value = event.data;
};

Response from previous request

{
    regular_request: {
        data: {
            name: "myname1",
            id: 1
        },
        statusCode: 200,
        headers: {
            "content-type": "application/json"
        }
    },
    persistentRequest: {
        data: "",
        headers: {
            "server": "Cowboy",
            "connection": "keep-alive",
            "x-powered-by": "Express",
            "content-type": "application/json; charset=utf-8",
            "content-length": "116",
            "etag": "W/\"74-1635811801\"",
            "date": "Mon, 12 Jan 2015 09:53:37 GMT",
            "via": "1.1 vegur"
        },
        "statusCode": 200,
        "cancelId": "jobName_37"
    }
}

Having in the response in the client cancelId we can send another request to the server and cancel the specific persistent request like:

var cancelMessage = {
	"cancelId": "jobName_1",
	"requestName": "persistentRequest"
};
ws.send(JSON.stringify(cancelMessage));