lightstreamer-adapter/lib/baseprotocol.js

This package includes the resources needed to write Data Adapters and Metadata Adapters for Lightstreamer Server in a Node.js environment. The adapters will run in a separate process, communicating with the Server through the Adapter Remoting Infrastructu

/*
Copyright (c) Lightstreamer Srl

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.
*/

// Module imports
var protocol =  require('./protocol');
var globals = require('./consts').globals;
var specialParameters = require('./consts').specialParameters;
var constants = require('./consts').constants;

function getSupportedVersion(protocolVersion) {
	// regardless of the protocol version requested, we want to speak at least 1.9.1
	// in order to support the delta delivery configuration extension offered to the Adapter
	if (protocolVersion != null) {
		if (protocolVersion.startsWith("1.8.")) {
			// protocol versions not supported
			return null;
		} else {
			return "1.9.1"; // maximum version supported
			// any upgrade or downgrade should be taken care by the caller
		}
	} else {
		// protocol version 1.8.0, not supported
		return null;
	}
}

function getCredentials(credentials, requestOutcome) {
	var credentialParams = {};
	if (credentials[specialParameters.USER] != null) {
		credentialParams[specialParameters.USER] = credentials[specialParameters.USER];
	}
	if (credentials[specialParameters.PASSWORD] != null) {
		credentialParams[specialParameters.PASSWORD] = credentials[specialParameters.PASSWORD];
	}
	if (requestOutcome) {
		credentialParams[specialParameters.OUTCOME] = "true";
	}
	credentialParams[specialParameters.SDK] = globals.SDK_NAME;
	return credentialParams;
}

function handleKeepalives(configuredInterval, requestedInterval, onFire) {
	if (requestedInterval <= 0 && configuredInterval <= 0) {
		// no need for keepalives
		return;
	}
	var interval;
	if (requestedInterval <= 0) {
		interval = configuredInterval;
	} else if (configuredInterval <= 0) {
		interval = requestedInterval;
	} else if (configuredInterval < requestedInterval) {
		interval = configuredInterval;
	} else {
		interval = requestedInterval;
	}
	if (interval < constants.MIN_KEEPALIVE_MILLIS) {
		interval = constants.MIN_KEEPALIVE_MILLIS;
	}

	setImmediate(onFire);
	var timer = setInterval(function() {
		try {
			if (! onFire()) {
				clearInterval(timer);
			}
		} catch (e) {
			clearInterval(timer);
		}
	}, interval);
	timer.unref();
}

function readInitParameters(message, tokens) {
	var i;
	message.ariVersion = null;
	message.keepaliveHint = null;
	// the requested version and keepalive hint are internal parameters, not to be sent to the custom Adapter
	message.parameters = {};
	for (i = 0; i < tokens.length; i = i + 4) {
		var propName = protocol.decodeStringOld(tokens[i + 1]);
		var propValue = protocol.decodeStringOld(tokens[i + 3]);
		if (specialParameters.ARI_VERSION === propName) {
			message.ariVersion = propValue;
		} else if (specialParameters.KEEPALIVE_HINT === propName) {
			message.keepaliveHint = propValue;
		} else {
			message.parameters[propName] = propValue;
		}
	}

	var advertisedVersion = getSupportedVersion(message.ariVersion);
	if (advertisedVersion != null) {
		// protocol version 1.9.0 and above;
		message.initResponseParams = {};
		message.initResponseParams[specialParameters.ARI_VERSION] = advertisedVersion;
	} else {
		// unsupported protocol version
		// we have to fail, but we will try to do it gracefully
		message.initResponseParams = null;
		message.diagnostics = "Unsupported protocol version";
	}
}

function readCloseParameters(message, tokens) {
	var i;
	message.parameters = {};
	for (i = 0; i < tokens.length; i = i + 4) {
		var propName = protocol.decodeStringOld(tokens[i + 1]);
		var propValue = protocol.decodeStringOld(tokens[i + 3]);
		message.parameters[propName] = propValue;
	}
}


// Module exports
exports.handleKeepalives = handleKeepalives;
exports.getCredentials = getCredentials;
exports.readInitParameters = readInitParameters;
exports.readCloseParameters = readCloseParameters;