"use strict";
var _ = require("underscore");
var subscription_service = require("node-opcua-service-subscription");
var assert = require("node-opcua-assert");
var debugLog = require("node-opcua-debug").make_debugLog(__filename);
var doDebug = require("node-opcua-debug").checkDebugFlag(__filename);
var StatusCodes = require("node-opcua-status-code").StatusCodes;
//xx var debugLog = console.log;
/**
* A client side implementation to deal with publish service.
*
* @class ClientSidePublishEngine
*
* @param session {ClientSession} - the client session
* @constructor
*
* The ClientSidePublishEngine encapsulates the mechanism to
* deal with a OPCUA Server and constantly sending PublishRequest
* The ClientSidePublishEngine also performs notification acknowledgements.
* Finally, ClientSidePublishEngine dispatch PublishResponse to the correct
* Subscription id callback
*/
function ClientSidePublishEngine(session) {
assert(session instanceof Object);
this.session = session;
this.subscriptionAcknowledgements = [];
this.subscriptionMap = {};
this.timeoutHint = 10000; // 10 s by default
this.activeSubscriptionCount = 0;
// number of pending Publish request sent to the server and awaited for being processed by the server
this.nbPendingPublishRequests = 0;
// the maximum number of publish requests we think that the server can queue.
// we will adjust this value .
this.nbMaxPublishRequestsAcceptedByServer = 1000;
this.isSuspended = false;
}
ClientSidePublishEngine.prototype.suspend = function(flag) {
assert(this.isSuspended !== !!flag,"invalid state");
this.isSuspended = !!flag;
if (this.isSuspended) {
} else {
this.replenish_publish_request_queue();
}
};
/**
* @method acknowledge_notification
* @param subscriptionId {Number} the subscription id
* @param sequenceNumber {Number} the sequence number
*/
ClientSidePublishEngine.prototype.acknowledge_notification = function (subscriptionId, sequenceNumber) {
//xx //xx console.log("xxxxxxx acknowledge_notification".bgWhite.red.bold, sequenceNumber);
//xx this._unacked = this._unacked || [];
//xx for (var i =this._lastAcked+1;i<sequenceNumber;i++) {
//xx //xx console.log("xxxxxxx acknowledge_notification => remembering unacked sequence number".bgWhite.red,i);
//xx this._unacked.push(i);
//xx }
//xx //xx assert(this.lastAcknowldegedSequence+1 === sequenceNumber,"expecting lastAcknowledgedSequence ");
//xx this._lastAcked = sequenceNumber;
this.subscriptionAcknowledgements.push({
subscriptionId: subscriptionId,
sequenceNumber: sequenceNumber
});
};
ClientSidePublishEngine.prototype.cleanup_acknowledgment_for_subscription = function (subscriptionId) {
this.subscriptionAcknowledgements = this.subscriptionAcknowledgements.filter(function (a) {
return a.subscriptionId !== subscriptionId;
});
};
/**
* @method send_publish_request
*/
ClientSidePublishEngine.prototype.send_publish_request = function () {
var self = this;
if (self.isSuspended) {
return;
}
if (self.nbPendingPublishRequests >= self.nbMaxPublishRequestsAcceptedByServer) {
return;
}
assert(self.subscriptionCount >0);
if (self.session && !self.session.isChannelValid()) {
setTimeout(function () {
if (self.subscriptionCount) {
self.send_publish_request();
}
}, 100);
} else {
setImmediate(function () {
if (!self.session) {
// session has been terminated
return;
}
self._send_publish_request();
});
}
};
ClientSidePublishEngine.prototype._send_publish_request = function () {
var self = this;
assert(self.session, "ClientSidePublishEngine terminated ?");
assert(!self.isSuspended,"should not be suspended");
self.nbPendingPublishRequests +=1;
debugLog("sending publish request ".yellow,self.nbPendingPublishRequests);
var subscriptionAcknowledgements = self.subscriptionAcknowledgements;
self.subscriptionAcknowledgements = [];
// as started in the spec (Spec 1.02 part 4 page 81 5.13.2.2 Function DequeuePublishReq())
// the server will dequeue the PublishRequest in first-in first-out order
// and will validate if the publish request is still valid by checking the timeoutHint in the RequestHeader.
// If the request timed out, the server will send a Bad_Timeout service result for the request and de-queue
// another publish request.
//
// in Part 4. page 144 Request Header the timeoutHint is described this way.
// timeoutHint UInt32 This timeout in milliseconds is used in the Client side Communication Stack to
// set the timeout on a per-call base.
// For a Server this timeout is only a hint and can be used to cancel long running
// operations to free resources. If the Server detects a timeout, he can cancel the
// operation by sending the Service result Bad_Timeout. The Server should wait
// at minimum the timeout after he received the request before cancelling the operation.
// The value of 0 indicates no timeout.
// In issue#40 (MonitoredItem on changed not fired), we have found that some server might wrongly interpret
// the timeoutHint of the request header ( and will bang a Bad_Timeout regardless if client send timeoutHint=0)
// as a work around here , we force the timeoutHint to be set to a suitable value.
//
// see https://github.com/node-opcua/node-opcua/issues/141
// This suitable value shall be at least the time between two keep alive signal that the server will send.
// (i.e revisedLifetimeCount * revisedPublishingInterval)
// also ( part 3 - Release 1.03 page 140)
// The Server shall check the timeoutHint parameter of a PublishRequest before processing a PublishResponse.
// If the request timed out, a Bad_Timeout Service result is sent and another PublishRequest is used.
// The value of 0 indicates no timeout
// in our case:
assert( self.nbPendingPublishRequests >0);
var calculatedTimeout = self.nbPendingPublishRequests * self.timeoutHint;
var publish_request = new subscription_service.PublishRequest({
requestHeader: {timeoutHint: calculatedTimeout}, // see note
subscriptionAcknowledgements: subscriptionAcknowledgements
});
var active = true;
self.session.publish(publish_request, function (err, response) {
self.nbPendingPublishRequests -= 1;
if (err) {
debugLog("ClientSidePublishEngine.prototype._send_publish_request callback : ".cyan, err.message.yellow);
debugLog("'" + err.message + "'");
if(err.message.match("not connected")) {
debugLog(" WARNING : CLIENT IS NOT CONNECTED : MAY BE RECONNECTION IS IN PROGRESS".bgWhite.red);
debugLog("self.activeSubscriptionCount =",self.activeSubscriptionCount);
// the previous publish request has ended up with an error because
// the connection has failed ...
// There is no need to send more publish request for the time being until reconnection is completed
active = false;
}
// istanbul ignore next
if (err.message.match(/BadNoSubscription/) && self.activeSubscriptionCount >=1) {
// there is something wrong happening here.
// the server tells us that there is no subscription for this session
// but the client have some active subscription left.
// This could happen if the client has missed or not received the StatusChange Notification
debugLog(" WARNING : SERVER TELLS THAT IT HAS NO SUBSCRIPTION , BUT CLIENT DISAGREE".bgWhite.red);
debugLog("self.activeSubscriptionCount =",self.activeSubscriptionCount);
active = false;
}
if (err.message.match(/BadSessionClosed|BadSessionIdInvalid/)) {
//
// server has closed the session ....
// may be the session timeout is shorted than the subscription life time
// and the client does not send intermediate keepAlive request to keep the connection working.
//
debugLog(" WARNING : SERVER TELLS THAT THE SESSION HAS CLOSED ...".bgWhite.red);
debugLog(" the ClientSidePublishEngine shall now be disabled, as server will reject any further request");
// close all active subscription....
active = false;
}
if (err.message.match(/BadTooManyPublishRequests/)) {
// preventing queue overflow
// -------------------------
// if the client send too many publish requests that the server can queue, the server returns
// a Service result of BadTooManyPublishRequests.
//
// let adjust the nbMaxPublishRequestsAcceptedByServer value so we never overflow the server
// with extraneous publish requests in the future.
//
self.nbMaxPublishRequestsAcceptedByServer = Math.min(self.nbPendingPublishRequests,self.nbMaxPublishRequestsAcceptedByServer);
active = false;
debugLog(" WARNING : SERVER TELLS THAT TOO MANY PUBLISH REQUEST HAS BEEN SEND ...".bgWhite.red);
debugLog(" On our side nbPendingPublishRequests = ",self.nbPendingPublishRequests);
debugLog(" => nbMaxPublishRequestsAcceptedByServer =",self.nbMaxPublishRequestsAcceptedByServer);
}
} else {
if (doDebug) {
debugLog("ClientSidePublishEngine.prototype._send_publish_request callback ".cyan);
}
self._receive_publish_response(response);
}
// feed the server with a new publish Request to the server
if (active && self.activeSubscriptionCount>0 ) {
self.send_publish_request();
}
});
};
ClientSidePublishEngine.prototype.terminate = function () {
this.session = null;
};
/**
* the number of active subscriptions managed by this publish engine.
* @property subscriptionCount
* @type {Number}
*/
ClientSidePublishEngine.prototype.__defineGetter__("subscriptionCount", function () {
var self = this;
return Object.keys(self.subscriptionMap).length;
});
ClientSidePublishEngine.publishRequestCountInPipeline = 5;
/**
* @method registerSubscription
*
* @param subscription.subscriptionId
* @param subscription.timeoutHint
* @param subscription.onNotificationMessage {Function} callback
*/
ClientSidePublishEngine.prototype.registerSubscription = function (subscription) {
debugLog("ClientSidePublishEngine#registerSubscription ", subscription.subscriptionId);
assert(arguments.length === 1);
var self = this;
assert(_.isFinite(subscription.subscriptionId));
assert(!self.subscriptionMap.hasOwnProperty(subscription.subscriptionId)); // already registered ?
assert(_.isFunction(subscription.onNotificationMessage));
assert(_.isFinite(subscription.timeoutHint));
self.activeSubscriptionCount += 1;
self.subscriptionMap[subscription.subscriptionId] = subscription;
self.timeoutHint = Math.max(self.timeoutHint, subscription.timeoutHint);
debugLog(" setting timeoutHint = ", self.timeoutHint, subscription.timeoutHint);
self.replenish_publish_request_queue();
};
ClientSidePublishEngine.prototype.replenish_publish_request_queue = function() {
var self = this;
// Spec 1.03 part 4 5.13.5 Publish
// [..] in high latency networks, the Client may wish to pipeline Publish requests
// to ensure cyclic reporting from the Server. Pipelining involves sending more than one Publish
// request for each Subscription before receiving a response. For example, if the network introduces a
// delay between the Client and the Server of 5 seconds and the publishing interval for a Subscription
// is one second, then the Client will have to issue Publish requests every second instead of waiting for
// a response to be received before sending the next request.
self.send_publish_request();
// send more than one publish request to server to cope with latency
for (var i = 0; i < ClientSidePublishEngine.publishRequestCountInPipeline - 1; i++) {
self.send_publish_request();
}
};
/**
* @method unregisterSubscription
*
* @param subscriptionId
*/
ClientSidePublishEngine.prototype.unregisterSubscription = function (subscriptionId) {
debugLog("ClientSidePublishEngine#unregisterSubscription ",subscriptionId);
assert(_.isFinite(subscriptionId) && subscriptionId >0);
var self = this;
self.activeSubscriptionCount -= 1;
assert(self.subscriptionMap.hasOwnProperty(subscriptionId));
delete self.subscriptionMap[subscriptionId];
};
ClientSidePublishEngine.prototype.getSubscriptionIds = function() {
var self = this;
return Object.keys(self.subscriptionMap).map(parseInt);
};
/***
* get the client subscription from Id
* @method getSubscription
* @param subscriptionId {Number} the subscription Id
* @return {Subscription|null}
*/
ClientSidePublishEngine.prototype.getSubscription = function (subscriptionId) {
var self = this;
assert(_.isFinite(subscriptionId) && subscriptionId >0);
assert(self.subscriptionMap.hasOwnProperty(subscriptionId));
return self.subscriptionMap[subscriptionId];
};
ClientSidePublishEngine.prototype._receive_publish_response = function (response) {
debugLog("receive publish response".yellow.bold);
var self = this;
// the id of the subscription sending the notification message
var subscriptionId = response.subscriptionId;
// the sequence numbers available in this subscription
// for retransmission and not acknowledged by the client
// -- var available_seq = response.availableSequenceNumbers;
// has the server more notification for us ?
// -- var moreNotifications = response.moreNotifications;
var notificationMessage = response.notificationMessage;
// notificationMessage.sequenceNumber
// notificationMessage.publishTime
// notificationMessage.notificationData[]
notificationMessage.notificationData = notificationMessage.notificationData || [];
if (notificationMessage.notificationData.length !== 0) {
self.acknowledge_notification(subscriptionId, notificationMessage.sequenceNumber);
}
//else {
// this is a keep-alive notification
// in this case , we shall not acknowledge notificationMessage.sequenceNumber
// which is only an information of what will be the future sequenceNumber.
//}
var subscription = self.subscriptionMap[subscriptionId];
if (subscription && self.session !== null) {
try{
// delegate notificationData to the subscription callback
subscription.onNotificationMessage(notificationMessage);
}
catch(err) {
if (doDebug){
console.log(err);
debugLog("Exception in onNotificationMessage" );
}
}
} else {
debugLog(" ignoring notificationMessage", notificationMessage, " for subscription", subscriptionId);
debugLog(" because there is no subscription.");
debugLog(" or because there is no session for the subscription (session terminated ?).");
}
};
var async = require("async");
ClientSidePublishEngine.prototype.republish = function(callback) {
var self = this;
// After re-establishing the connection the Client shall call Republish in a loop, starting with the next expected
// sequence number and incrementing the sequence number until the Server returns the status Bad_MessageNotAvailable.
// After receiving this status, the Client shall start sending Publish requests with the normal Publish handling.
// This sequence ensures that the lost NotificationMessages queued in the Server are not overwritten by new
// Publish responses
function _republish(subscription,subscriptionId,_i_callback) {
assert(subscription.subscriptionId === +subscriptionId);
var is_done = false;
function _send_republish(_b_callback) {
var request = new subscription_service.RepublishRequest({
subscriptionId: subscription.subscriptionId,
retransmitSequenceNumber: subscription.lastSequenceNumber+1
});
// istanbul ignore next
if (doDebug) {
debugLog(" republish Request for subscription".bgCyan.yellow.bold,
request.subscriptionId," retransmitSequenceNumber=",request.retransmitSequenceNumber);
}
self.session.republish(request,function(err,response){
if (!err && response.responseHeader.serviceResult === StatusCodes.Good) {
subscription.onNotificationMessage(response.notificationMessage);
} else {
if (!err) {
err = response.responseHeader.serviceResult.toString();
}
debugLog(" _send_republish ends with ",err.message);
is_done = true;
}
_b_callback(err);
});
}
setImmediate(function() {
assert(_.isFunction(_i_callback));
async.whilst(function (){ return !is_done},_send_republish,function(err) {
debugLog("nbPendingPublishRequest = ",self.nbPendingPublishRequests);
debugLog(" _republish ends with ",err ? err.message : "null");
_i_callback(err);
});
});
}
function repairSubscription(subscription,subscriptionId,_the_callback) {
_republish(subscription,subscriptionId,function (err) {
if (err && err.message.match(/SubscriptionIdInvalid/)) {
// _republish failed because subscriptionId is not valid anymore on server side.
//
// This could happen when the subscription has timed out and has been deleted by server
// Subscription may time out if the duration of the connection break exceed the max life time
// of the subscription.
//
// In this case, Client must recreate a subscription and recreate monitored item without altering
// the event handlers
//
debugLog("_republish failed because subscriptionId is not valid anymore on server side.".bgWhite.red);
return subscription.recreateSubscriptionAndMonitoredItem(_the_callback);
}
_the_callback();
});
}
async.forEachOf(self.subscriptionMap,repairSubscription,callback);
};
exports.ClientSidePublishEngine = ClientSidePublishEngine;
The NodeOPCUA API