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  • SQL 2008 publisher -> SQL 2000 subscriber: Is a pull subscription possible for merge replication?

    - by Brian Dunzweiler
    I am trying to synchronize a SQL 2000 SP4 subscriber to a SQL 2008 publisher via a merge pull subscription. When the subscriber tries to run the merge agent, it fails the following error: The process could not connect to Distributor 'OH05DBS002\SAM_SSG_2008'. SQL Server does not exist or access denied. Has anyone had success with this setup? I was able to create and synchronize a push subscription so I know that communication works between the two, at least from 2008-2000. The lack of communication from 2000-2008 also affects the ability to create a linked server on the SQL 2000 subscriber. One other tidbit - I did install the SQL 2008 native client on the the 2000 box but it didn't help either. Before anyone asks, I can't upgrade the subscriber as it still needs to support replication between MS Access 2003. Yeah, I know. :) TIA, Brian

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  • C#: Handling Notifications: inheritance, events, or delegates?

    - by James Michael Hare
    Often times as developers we have to design a class where we get notification when certain things happen. In older object-oriented code this would often be implemented by overriding methods -- with events, delegates, and interfaces, however, we have far more elegant options. So, when should you use each of these methods and what are their strengths and weaknesses? Now, for the purposes of this article when I say notification, I'm just talking about ways for a class to let a user know that something has occurred. This can be through any programmatic means such as inheritance, events, delegates, etc. So let's build some context. I'm sitting here thinking about a provider neutral messaging layer for the place I work, and I got to the point where I needed to design the message subscriber which will receive messages from the message bus. Basically, what we want is to be able to create a message listener and have it be called whenever a new message arrives. Now, back before the flood we would have done this via inheritance and an abstract class: 1:  2: // using inheritance - omitting argument null checks and halt logic 3: public abstract class MessageListener 4: { 5: private ISubscriber _subscriber; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber) 11: { 12: _subscriber = subscriber; 13: _messageThread = new Thread(MessageLoop); 14: _messageThread.Start(); 15: } 16:  17: // user will override this to process their messages 18: protected abstract void OnMessageReceived(Message msg); 19:  20: // handle the looping in the thread 21: private void MessageLoop() 22: { 23: while(!_isHalted) 24: { 25: // as long as processing, wait 1 second for message 26: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 27: if(msg != null) 28: { 29: OnMessageReceived(msg); 30: } 31: } 32: } 33: ... 34: } It seems so odd to write this kind of code now. Does it feel odd to you? Maybe it's just because I've gotten so used to delegation that I really don't like the feel of this. To me it is akin to saying that if I want to drive my car I need to derive a new instance of it just to put myself in the driver's seat. And yet, unquestionably, five years ago I would have probably written the code as you see above. To me, inheritance is a flawed approach for notifications due to several reasons: Inheritance is one of the HIGHEST forms of coupling. You can't seal the listener class because it depends on sub-classing to work. Because C# does not allow multiple-inheritance, I've spent my one inheritance implementing this class. Every time you need to listen to a bus, you have to derive a class which leads to lots of trivial sub-classes. The act of consuming a message should be a separate responsibility than the act of listening for a message (SRP). Inheritance is such a strong statement (this IS-A that) that it should only be used in building type hierarchies and not for overriding use-specific behaviors and notifications. Chances are, if a class needs to be inherited to be used, it most likely is not designed as well as it could be in today's modern programming languages. So lets look at the other tools available to us for getting notified instead. Here's a few other choices to consider. Have the listener expose a MessageReceived event. Have the listener accept a new IMessageHandler interface instance. Have the listener accept an Action<Message> delegate. Really, all of these are different forms of delegation. Now, .NET events are a bit heavier than the other types of delegates in terms of run-time execution, but they are a great way to allow others using your class to subscribe to your events: 1: // using event - ommiting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private bool _isHalted = false; 6: private Thread _messageThread; 7:  8: // assign the subscriber and start the messaging loop 9: public MessageListener(ISubscriber subscriber) 10: { 11: _subscriber = subscriber; 12: _messageThread = new Thread(MessageLoop); 13: _messageThread.Start(); 14: } 15:  16: // user will override this to process their messages 17: public event Action<Message> MessageReceived; 18:  19: // handle the looping in the thread 20: private void MessageLoop() 21: { 22: while(!_isHalted) 23: { 24: // as long as processing, wait 1 second for message 25: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 26: if(msg != null && MessageReceived != null) 27: { 28: MessageReceived(msg); 29: } 30: } 31: } 32: } Note, now we can seal the class to avoid changes and the user just needs to provide a message handling method: 1: theListener.MessageReceived += CustomReceiveMethod; However, personally I don't think events hold up as well in this case because events are largely optional. To me, what is the point of a listener if you create one with no event listeners? So in my mind, use events when handling the notification is optional. So how about the delegation via interface? I personally like this method quite a bit. Basically what it does is similar to inheritance method mentioned first, but better because it makes it easy to split the part of the class that doesn't change (the base listener behavior) from the part that does change (the user-specified action after receiving a message). So assuming we had an interface like: 1: public interface IMessageHandler 2: { 3: void OnMessageReceived(Message receivedMessage); 4: } Our listener would look like this: 1: // using delegation via interface - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private IMessageHandler _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler.OnMessageReceived(msg); 28: } 29: } 30: } 31: } And they would call it by creating a class that implements IMessageHandler and pass that instance into the constructor of the listener. I like that this alleviates the issues of inheritance and essentially forces you to provide a handler (as opposed to events) on construction. Well, this is good, but personally I think we could go one step further. While I like this better than events or inheritance, it still forces you to implement a specific method name. What if that name collides? Furthermore if you have lots of these you end up either with large classes inheriting multiple interfaces to implement one method, or lots of small classes. Also, if you had one class that wanted to manage messages from two different subscribers differently, it wouldn't be able to because the interface can't be overloaded. This brings me to using delegates directly. In general, every time I think about creating an interface for something, and if that interface contains only one method, I start thinking a delegate is a better approach. Now, that said delegates don't accomplish everything an interface can. Obviously having the interface allows you to refer to the classes that implement the interface which can be very handy. In this case, though, really all you want is a method to handle the messages. So let's look at a method delegate: 1: // using delegation via delegate - omitting argument null checks and halt logic 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // handle the looping in the thread 19: private void MessageLoop() 20: { 21: while(!_isHalted) 22: { 23: // as long as processing, wait 1 second for message 24: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 25: if(msg != null) 26: { 27: _handler(msg); 28: } 29: } 30: } 31: } Here the MessageListener now takes an Action<Message>.  For those of you unfamiliar with the pre-defined delegate types in .NET, that is a method with the signature: void SomeMethodName(Message). The great thing about delegates is it gives you a lot of power. You could create an anonymous delegate, a lambda, or specify any other method as long as it satisfies the Action<Message> signature. This way, you don't need to define an arbitrary helper class or name the method a specific thing. Incidentally, we could combine both the interface and delegate approach to allow maximum flexibility. Doing this, the user could either pass in a delegate, or specify a delegate interface: 1: // using delegation - give users choice of interface or delegate 2: public sealed class MessageListener 3: { 4: private ISubscriber _subscriber; 5: private Action<Message> _handler; 6: private bool _isHalted = false; 7: private Thread _messageThread; 8:  9: // assign the subscriber and start the messaging loop 10: public MessageListener(ISubscriber subscriber, Action<Message> handler) 11: { 12: _subscriber = subscriber; 13: _handler = handler; 14: _messageThread = new Thread(MessageLoop); 15: _messageThread.Start(); 16: } 17:  18: // passes the interface method as a delegate using method group 19: public MessageListener(ISubscriber subscriber, IMessageHandler handler) 20: : this(subscriber, handler.OnMessageReceived) 21: { 22: } 23:  24: // handle the looping in the thread 25: private void MessageLoop() 26: { 27: while(!_isHalted) 28: { 29: // as long as processing, wait 1 second for message 30: Message msg = _subscriber.Receive(TimeSpan.FromSeconds(1)); 31: if(msg != null) 32: { 33: _handler(msg); 34: } 35: } 36: } 37: } } This is the method I tend to prefer because it allows the user of the class to choose which method works best for them. You may be curious about the actual performance of these different methods. 1: Enter iterations: 2: 1000000 3:  4: Inheritance took 4 ms. 5: Events took 7 ms. 6: Interface delegation took 4 ms. 7: Lambda delegate took 5 ms. Before you get too caught up in the numbers, however, keep in mind that this is performance over over 1,000,000 iterations. Since they are all < 10 ms which boils down to fractions of a micro-second per iteration so really any of them are a fine choice performance wise. As such, I think the choice of what to do really boils down to what you're trying to do. Here's my guidelines: Inheritance should be used only when defining a collection of related types with implementation specific behaviors, it should not be used as a hook for users to add their own functionality. Events should be used when subscription is optional or multi-cast is desired. Interface delegation should be used when you wish to refer to implementing classes by the interface type or if the type requires several methods to be implemented. Delegate method delegation should be used when you only need to provide one method and do not need to refer to implementers by the interface name.

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  • Getting Feedburner Subscriber With CURL

    - by Eray Alakese
    I'm using FeedBurner Awareness API. XML data like this : <rsp stat="ok"> - <!-- This information is part of the FeedBurner Awareness API. If you want to hide this information, you may do so via your FeedBurner Account. --> - <feed id="9n66llmt1frfir51p0oa367ru4" uri="teknoblogo"> <entry date="2011-01-15" circulation="11" hits="18" reach="0"/> </feed> </rsp> I want to get circulation data (11) . I'm using this code: $whaturl="https://feedburner.google.com/api/awareness/1.0/GetFeedData?uri=teknoblogo"; //Initialize the Curl session $ch = curl_init(); //Set curl to return the data instead of printing it to the browser. curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); //Set the URL curl_setopt($ch, CURLOPT_URL, $whaturl); //Execute the fetch $data = curl_exec($ch); //Close the connection curl_close($ch); $xml = new SimpleXMLElement($data); $fb = $xml->feed->entry['circulation']; echo $fb; echo "OK"; But, returned data is blank. There isn't any error. Only return OK . How can i solve this ? EDIT : echo $data; returning blank, too.

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  • MVC 3 ModelView passing parameters between view & controller

    - by Tobias Vandenbempt
    I've been playing with MVC 3 in a test project and have the following issue. I have Group & Subscriber entities and those are coupled through a SubscriberGroup table. Using the DetailView of Group I open a view of SubscriberGroup containing all subscribers. This list has the option to filter. So far it all works, however when I call the AddToGroup method on the controller it fails. Specifically it goes into the method but doesn't pass the subscriberCheckedModels list. Am I doing something wrong? View: SubscriberGroup Index.aspx <%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.master" Inherits="System.Web.Mvc.ViewPage<Mail.Models.SubscriberCheckedListViewModel>" %> … <h2 class="common-box-title"> Add Subscribers to Group</h2> <p> <% using (Html.BeginForm("Index", "SubscriberGroup")) { %> <input name="filter" id="filter" type="text" /> <input type="submit" value="Search" /> <%} %> </p> <% using (Html.BeginForm("AddToGroup", "SubscriberGroup", Model,FormMethod.Get, null)) { %> <fieldset> <div style="display: inline-block; width: 70%; vertical-align: top;"> <% if (Model.subscribers.Count() != 0) { %> <table class="hor-minimalist-b"> <tr> <th> Add To Group </th> <th> Full Name </th> <th> Email </th> <th> Customer </th> </tr> <% foreach (var item in Model.subscribers) { %> <tr> <td> <%= Html.CheckBoxFor(modelItem => item.AddToGroup)%> </td> <td> <%= Html.DisplayFor(modelItem => item.subscriber.LastName)%> <%= Html.ActionLink(item.subscriber.FirstName + " " + item.subscriber.LastName, "Details", new { id = item.subscriber.SubscriberID })%> </td> <td> <%: Html.DisplayFor(modelItem => item.subscriber.Email)%> </td> <td> <%: Html.DisplayFor(modelItem => item.subscriber.Customer.Company)%> <%= Html.HiddenFor(modelItem => item.subscriber) %> </td> </tr> <% } %> <% ViewBag.subscribers = Model.subscribers; %> probeersel <%= Html.HiddenFor(model => model.subscribers) %> probeersel </table> <%} %> <%else { %> <p> No subscribers found.</p> <%} %> <input type="submit" value="Add Subscribers" /> </div> </fieldset> <%} %> Controller: SubscriberGroupController using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; using System.Web.Security; using Mail.Models; namespace Mail.Controllers { public class SubscriberGroupController : Controller { private int groupID; private MailDBEntities db = new MailDBEntities(); // // GET: /SubscriberGroup/ public ActionResult Index(int id) { groupID = id; MembershipUser myObject = Membership.GetUser(); Guid UserID = Guid.Parse(myObject.ProviderUserKey.ToString()); UserCustomer usercustomer = db.UserCustomers.Single(s => s.UserID == UserID); var subscribers = from subscriber in db.Subscribers where (subscriber.CustomerID == usercustomer.CustomerID) | (subscriber.CustomerID == 0) select new SubscriberCheckedModel { subscriber = subscriber, AddToGroup = false }; SubscriberCheckedListViewModel test = new SubscriberCheckedListViewModel(); test.subscribers = subscribers; return View(test); } [HttpPost] public ActionResult Index(string filter) { MembershipUser myObject = Membership.GetUser(); Guid UserID = Guid.Parse(myObject.ProviderUserKey.ToString()); UserCustomer usercustomer = db.UserCustomers.Single(s => s.UserID == UserID); var subscribers2 = from subscriber in db.Subscribers where ((subscriber.FirstName.Contains(filter)|| subscriber.LastName.Contains(filter)) && (subscriber.CustomerID == usercustomer.CustomerID || subscriber.CustomerID == 0)) select new SubscriberCheckedModel { subscriber = subscriber, AddToGroup = false }; SubscriberCheckedListViewModel test = new SubscriberCheckedListViewModel(); test.subscribers = subscribers2.ToList(); return View(test); } [HttpPost] public ActionResult AddToGroup(SubscriberCheckedListViewModel test) { //test is null return RedirectToAction("Details", "Group", new { id = groupID }); } } } ViewModel: SubscriberGroupModel using System.Collections.Generic; using Mail; namespace Mail.Models { public class SubscriberCheckedModel { public Subscriber subscriber { get; set; } public bool AddToGroup { get; set; } } public class SubscriberCheckedListViewModel { public IEnumerable<SubscriberCheckedModel> subscribers { get; set; } } }

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  • If a SQL Server Replication Distributor and Subscriber are on the same server, should a PUSH or PULL subsciption be used?

    - by userx
    Thanks in advance for any help. I'm setting up a new Microsoft SQL Server replication and I have the Distributor and Subscriber running on the same server. The Publisher is on a remote server (as it is a production database and MS recommends that for high volumes, the Distributor should be remote). I don't know much about the inner workings of PUSH vs PULL subscriptions, but my gut tells me that a PUSH subscription would be less resource intensive because (1) the Distributor is already remote, so this shouldn't negatively effect the Publisher and (2) pushing the transactions from the Distributor to the Subscriber is more efficient than the Subscriber polling the Distribution database. Does any one have any resources or insight into PUSH vs PULL which would recommend one over the other? Is there really going to be that big of a difference in performance / reliability / security?

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  • How to create a JMS durable subscriber in WebLogic Server?

    - by lmestre
    WebLogic Server Provides a set of examples that are very helpful to get started with Weblogic ServerHere you can check how to install the examples:http://docs.oracle.com/cd/E23943_01/doc.1111/e14142/prepare.htmAfter you have installed the examples, you can find the example you want to review, in this case TopicReceive, here:wlserver_10.3/samples/server/examples/src/examples/jms/topicTo review details of the specific example, you can open:wlserver_10.3/samples/server/examples/src/examples/jms/topic/instructions.htmlTo create a Durable Subscriber, you can just set the client ID  and invoke createDurableSubscriber instead of calling createSubscriber, i.e.:    tconFactory = (TopicConnectionFactory)       PortableRemoteObject.narrow(ctx.lookup(JMS_FACTORY),                                   TopicConnectionFactory.class);    tcon = tconFactory.createTopicConnection();    //Set Client ID for this Durable Subscriber    tcon.setClientID("GT2");    tsession = tcon.createTopicSession(false, Session.AUTO_ACKNOWLEDGE);    topic = (Topic)       PortableRemoteObject.narrow(ctx.lookup(topicName),                                   Topic.class);    // Create Durable Subscription    tsubscriber = tsession.createDurableSubscriber(topic, "Test");    tsubscriber.setMessageListener(this);    tcon.start(); Enjoy!   You can read more about this here:http://docs.oracle.com/cd/E23943_01/web.1111/e13727/advpubsub.htm#CHDEBABChttp://docs.oracle.com/cd/E23943_01/web.1111/e13727/manage_apps.htm#i1097671    http://docs.oracle.com/cd/E23943_01/apirefs.1111/e13943/WebLogic.Messaging.ISession.CreateDurableSubscriber_overload_2.html

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  • Paypal "Subscribe" button: Is it possible to let the subscriber set the amount?

    - by Šime Vidas
    I'm setting up a recurring payment option on my website. I'd like to have two options: Option 1 (for individuals): Fixed $6/mo subscription Option 2 (for organizations): A subscription where the amount is set by the subscriber PayPal's "Subscribe" button does not seem to allow that: When I leave the "Amount" field of the 2nd option empty, I get an error: So, is this not possible? Do all options require fixed amounts?

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  • Complex event system for DungeonKeeper like game

    - by paul424
    I am working on opensource GPL3 game. http://opendungeons.sourceforge.net/ , new coders would be welcome. Now there's design question regarding Event System: We want to improve the game logic, that is program a new event system. I will just repost what's settled up already on http://forum.freegamedev.net/viewtopic.php?f=45&t=3033. From the discussion came the idea of the Publisher / Subscriber pattern + "domains": My current idea is to use the subscirbers / publishers model. Its similar to Observable pattern, but instead one subscribes to Events types, not Object's Events. For each Event would like to have both static and dynamic type. Static that is its's type would be resolved by belonging to the proper inherited class from Event. That is from Event we would have EventTile, EventCreature, EvenMapLoader, EventGameMap etc. From that there are of course subtypes like EventCreature would be EventKobold, EventKnight, EventTentacle etc. The listeners would collect the event from publishers, and send them subcribers , each of them would be a global singleton. The Listeners type hierachy would exactly mirror the type hierarchy of Events. In each constructor of Event type, the created instance would notify the proper listeners. That is when calling EventKnight the proper ctor would notify the Listeners : EventListener, CreatureLisener and KnightListener. The default action for an listner would be to notify all subscribers, but there would be some exceptions , like EventAttack would notify AttackListener which would dispatch event by the dynamic part ( that is the Creature pointer or hash). Any comments ? #include <vector> class Subscriber; class SubscriberAttack; class Event{ private: int foo; int bar; protected: // static std::vector<Publisher*> publishersList; static std::vector<Subscriber*> subscribersList; static std::vector<Event*> eventQueue; public: Event(){ eventQueue.push_back(this); } static int subscribe(Subscriber* ss); static int unsubscribe(Subscriber* ss); //static int reg_publisher(Publisher* pp); //static int unreg_publisher(Publisher* pp); }; // class Publisher{ // }; class Subscriber{ public: int (*newEvent) (Event* ee); Subscriber( ){ Event::subscribe(this); } Subscriber( int (*fp) (Event* ee) ):newEvent(fp){ Subscriber(); } ~Subscriber(){ Event::unsubscribe(this); } }; class EventAttack: Event{ private: int foo; int bar; protected: // static std::vector<Publisher*> publishersList; static std::vector<SubscriberAttack*> subscribersList; static std::vector<EventAttack*> eventQueue; public: EventAttack(){ eventQueue.push_back(this); } static int subscribe(SubscriberAttack* ss); static int unsubscribe(SubscriberAttack* ss); //static int reg_publisher(Publisher* pp); //static int unreg_publisher(Publisher* pp); }; class AttackSubscriber :Subscriber{ public: int (*newEvent) (EventAttack* ee); AttackSubscriber( ){ EventAttack::subscribe(this); } AttackSubscriber( int (*fp) (EventAttack* ee) ):newEventAttack(fp){ AttackSubscriber(); } ~AttackSubscriber(){ EventAttack::unsubscribe(this); } }; From that point, others wanted the Subject-Observer pattern, that is one would subscribe to all event types produced by particular object. That way it came out to add the domain system : Huh, to meet the ability to listen to particular game's object events, I though of introducing entity domains . Domains are trees, which nodes are labeled by unique names for each level. ( like the www addresses ). Each Entity wanting to participate in our event system ( that is be able to publish / produce events ) should at least now its domain name. That would end up in Player1/Room/Treasury/#24 or Player1/Creature/Kobold/#3 producing events. The subscriber picks some part of a tree. For example by specifiing subtree with the root in one of the nodes like Player1/Room/* ,would subscribe us to all Players1's room's event, and Player1/Creature/Kobold/#3 would subscribe to Players' third kobold's event. Does such event system make sense to you ? I have many implementation details to ask as well, but first let's start some general discussion. Note1: Notice that in the case of a fight between two creatues fight , the creature being attacked would have to throw an event, becuase it is HE/SHE/IT who have its domain address. So that would be BeingAttackedEvent() etc. I will edit that post if some other reflections on this would come out. Note2: the existing class hierarchy might be used to get the domains addresses being build in constructor . In a ctor you would just add + ."className" to domain address. If you are in a class'es hierarchy leaf constructor one might use nextID , hash or any other charactteristic, just to make the addresses distinguishable . Note3:subscribing to all entity's Events would require knowledge of all possible events produced by this entity . This could be done in one function call, but information on E produced would have to be handled for every Entity. SmartNote4 : Finding proper subscribers in a tree would be easy. One would start in particular Leaf for example Player1/Creature/Kobold/#3 and go up one parent a time , notifiying each Subscriber in a Node ie. : Player1/Creature/Kobold/* , Player1/Creature/* , Player1/* etc, , up to a root that is /* .<<<< Note5: The Event system was needed to have some way of incorporating Angelscript code into application. So the Event dispatcher was to be a gate to A-script functions. But it came out to this one.

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  • Timestamp issue with localtime and mktime

    - by egiakoum1984
    Please see the code below: #include <iostream> #include <stdlib.h> #include <time.h> using namespace std; int main(void) { time_t current_time = 1270715952; cout << "Subscriber current timestamp:" << current_time << endl; tm* currentTm = localtime(&current_time); char tmp_str[256]; //2010-04-08T11:39:12 snprintf(tmp_str, sizeof(tmp_str), "%04d%02d%02d%02d%02d%02d.000", currentTm->tm_year+1900, currentTm->tm_mon+1, currentTm->tm_mday, currentTm->tm_hour, currentTm->tm_min, currentTm->tm_sec); cout << "Subscriber current date:" << tmp_str << endl; tm tmpDateScheduleFrom, tmpDateScheduleTo; memset(&tmpDateScheduleFrom, 0, sizeof(tm)); memset(&tmpDateScheduleTo, 0, sizeof(tm)); //2010-04-08T11:00 tmpDateScheduleFrom.tm_sec = 0; tmpDateScheduleFrom.tm_min = 0; tmpDateScheduleFrom.tm_hour = 11; tmpDateScheduleFrom.tm_mday = 8; tmpDateScheduleFrom.tm_mon = 3; tmpDateScheduleFrom.tm_year = 110; //2010-04-08T12:00 tmpDateScheduleTo.tm_sec = 0; tmpDateScheduleTo.tm_min = 0; tmpDateScheduleTo.tm_hour = 12; tmpDateScheduleTo.tm_mday = 8; tmpDateScheduleTo.tm_mon = 3; tmpDateScheduleTo.tm_year = 110; time_t localFrom = mktime(&tmpDateScheduleFrom); time_t localTo = mktime(&tmpDateScheduleTo); cout << "Subscriber current timestamp:" << current_time << endl; cout << "Subscriber localFrom:" << localFrom << endl; cout << "Subscriber localTo:" << localTo << endl; return 0; } The results are the following: Subscriber current timestamp:1270715952 Subscriber current date:20100408113912.000 Subscriber current timestamp:1270715952 Subscriber localFrom:1270717200 Subscriber localTo:1270720800 Why the current subscriber timestamp (subscriber date and time: 2010-04-08T11:39:12) is not between the range localFrom (timestamp of date/time: 2010-04-08T11:00:00) and LocalTo (timestamp of date/time: 2010-04-08T12:00:00)?

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  • Design question - loading info from DB

    - by eriks
    I need to build a class that will represent a row in some table in DB (lets say the table is 'Subscriber' and so is the class). I can have the class Subscriber which constructor receives the Objectkey of subscriber, retrieves info from DB and initializes its members. I add another class - SubscriberLoader which have a static method 'LoadSubscriber'. This method will receive the subscriber objectkey, retrieve info from DB, crate a Subscriber object and initialize its members. Subscriber constructor will be private and SubscirberLoader will be friend class of Subscriber - this way, client could build a Subscriber only using the loader. which of the two in better? any other suggestions?

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  • Is there a better way to format this Python/Django code as valid PEP8?

    - by Ryan Detzel
    I have code written both ways and I see flaws in both of them. Is there another way to write this or is one approach more "correct" than the other? def functionOne(subscriber): try: results = MyModelObject.objects.filter( project__id=1, status=MyModelObject.STATUS.accepted, subscriber=subscriber).values_list( 'project_id', flat=True).order_by('-created_on') except: pass def functionOne(subscriber): try: results = MyModelObject.objects.filter( project__id=1, status=MyModelObject.STATUS.accepted, subscriber=subscriber) results = results.values_list('project_id', flat=True) results = results.order_by('-created_on') except: pass

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  • Should I never put a transactional replication distributor on a subscriber server?

    - by Stuart Branham
    What factors into choosing a distribution server for transactional replication? In our topology, we've always had the distributor reside on the publishing server. We rarely generate snapshots and performance is good enough, so this is okay for us today. One of our instances is moving to a cluster, so we need to move the distributor off for resilience/symmetry. Right now our two choices are to use a server physically close to the publishers, or our single subscription server. Our publisher is in our main office, and our subscriber is in a colocation facility off-site which our ISP runs. We have a pretty good line to it. The reason we're even considering the latter is to save work and licensing costs.

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  • How do I push my initial snapshot to a subscriber server in SQL Server 2000?

    - by Kev
    I'm configuring Transactional Replication using the Push model. The scenario is: The SQL Servers: SQL01 (publisher) and SQL02 (subscriber) - both running SQL 2000 SP4. Both servers are standalone (i.e. not domain members) Both servers have their FQDN and NETBIOS names in their HOSTS files I've managed to configure SQL01 to publish my database and configured a Push subscription for SQL02 using the Push New Subscription wizard and set the Distribution Agent to update the subscription continuously. On the Push Subscription wizard "Initialise Subscription" page I've selected "Yes, initialise the schema and data" and ticked the "Start the Snapshot Agent to begin the initialisation process immediately" option. All the required services are running (SQL Agent). When I complete the wizard and browse the Replication - Publications folder I can see my publication (blue book with arrow). The publication shows the Push subscription and its status is Pending. If I look in the c:\Program Files\Microsoft SQL Server\Mssql\Repldata folder I see a number of T-SQL scripts for each table e.g. Products.bcp, Products.sch, Products.idx. What should happen now? Should my replicated database now (magically) appear on the subscription server?

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  • Why don't RSpec's methods, "get", "post", "put", "delete" work in a controller spec in a gem (or out

    - by ramon.tayag
    I'm not new to Rails or Rspec, but I'm new to making gems. When I test my controllers, the REST methods "get", "post", "put", "delete" give me an undefined method error. Below you'll find code, but if you prefer to see it in a pastie, click here. Thanks! Here's my spec_helper: $LOAD_PATH.unshift(File.dirname(__FILE__)) $LOAD_PATH.unshift(File.join(File.dirname(__FILE__), '..', 'lib')) require 'rubygems' require 'active_support' unless defined? ActiveSupport # Need this so that mattr_accessor will work in Subscriber module require 'active_record/acts/subscribable' require 'active_record/acts/subscriber' require 'action_view' require 'action_controller' # Since we'll be testing subscriptions controller #require 'action_controller/test_process' require 'spec' require 'spec/autorun' # Need active_support to user mattr_accessor in Subscriber module, and to set the following inflection ActiveSupport::Inflector.inflections do |inflect| inflect.irregular 'dorkus', 'dorkuses' end require 'active_record' # Since we'll be testing a User model which will be available in the app # Tell active record to load the subscribable files ActiveRecord::Base.send(:include, ActiveRecord::Acts::Subscribable) ActiveRecord::Base.send(:include, ActiveRecord::Acts::Subscriber) require 'app/models/user' # The user model we expect in the application require 'app/models/person' require 'app/models/subscription' require 'app/models/dorkus' require 'app/controllers/subscriptions_controller' # The controller we're testing #... more but I think irrelevant My subscriptions_spec: require File.expand_path(File.dirname(__FILE__) + '/../spec_helper') describe SubscriptionsController, "on GET index" do load_schema describe ", when only subscribable params are passed" do it "should list all the subscriptions of the subscribable object" end describe ", when only subscriber params are passed" do it "should list all the subscriptions of the subscriber" do u = User.create d1 = Dorkus.create d2 = Dorkus.create d1.subscribe! u d2.subscribe! u get :index, {:subscriber_type = "User", :subscriber_id = u.id} assigns[:subscriptions].should == u.subscriptions end end end My subscriptions controller: class SubscriptionsController The error: NoMethodError in 'SubscriptionsController on GET index , when only subscriber params are passed should list all the subscriptions of the subscriber' undefined method `get' for # /home/ramon/rails/acts_as_subscribable/spec/controllers/subscriptions_controller_spec.rb:21:

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  • Can I use Pub/Sub model with Many Publishers and Only One Subscriber?

    - by rauch
    I need to send some files from different machines to only one Server. As I understand, I can use JMS api + (for example) ActiveMQ as broker. There are two models: p2p and pub/sub. I would like to use pub/sub model, but the problem is that I haven`t few subscribers, I have only one Subscriber(Server) and many Publishers. The question is the following: can I use pub/sub model for my situation and How can I send files from different machines to Only One Topic, on that Server sibscribed? May be any other ideas, thanks a lot.

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  • Should I expose IObservable<T> on my interfaces?

    - by Alex
    My colleague and I have dispute. We are writing a .NET application that processes massive amounts of data. It receives data elements, groups subsets of them into blocks according to some criterion and processes those blocks. Let's say we have data items of type Foo arriving some source (from the network, for example) one by one. We wish to gather subsets of related objects of type Foo, construct an object of type Bar from each such subset and process objects of type Bar. One of us suggested the following design. Its main theme is exposing IObservable objects directly from the interfaces of our components. // ********* Interfaces ********** interface IFooSource { // this is the event-stream of objects of type Foo IObservable<Foo> FooArrivals { get; } } interface IBarSource { // this is the event-stream of objects of type Bar IObservable<Bar> BarArrivals { get; } } / ********* Implementations ********* class FooSource : IFooSource { // Here we put logic that receives Foo objects from the network and publishes them to the FooArrivals event stream. } class FooSubsetsToBarConverter : IBarSource { IFooSource fooSource; IObservable<Bar> BarArrivals { get { // Do some fancy Rx operators on fooSource.FooArrivals, like Buffer, Window, Join and others and return IObservable<Bar> } } } // this class will subscribe to the bar source and do processing class BarsProcessor { BarsProcessor(IBarSource barSource); void Subscribe(); } // ******************* Main ************************ class Program { public static void Main(string[] args) { var fooSource = FooSourceFactory.Create(); var barsProcessor = BarsProcessorFactory.Create(fooSource) // this will create FooSubsetToBarConverter and BarsProcessor barsProcessor.Subscribe(); fooSource.Run(); // this enters a loop of listening for Foo objects from the network and notifying about their arrival. } } The other suggested another design that its main theme is using our own publisher/subscriber interfaces and using Rx inside the implementations only when needed. //********** interfaces ********* interface IPublisher<T> { void Subscribe(ISubscriber<T> subscriber); } interface ISubscriber<T> { Action<T> Callback { get; } } //********** implementations ********* class FooSource : IPublisher<Foo> { public void Subscribe(ISubscriber<Foo> subscriber) { /* ... */ } // here we put logic that receives Foo objects from some source (the network?) publishes them to the registered subscribers } class FooSubsetsToBarConverter : ISubscriber<Foo>, IPublisher<Bar> { void Callback(Foo foo) { // here we put logic that aggregates Foo objects and publishes Bars when we have received a subset of Foos that match our criteria // maybe we use Rx here internally. } public void Subscribe(ISubscriber<Bar> subscriber) { /* ... */ } } class BarsProcessor : ISubscriber<Bar> { void Callback(Bar bar) { // here we put code that processes Bar objects } } //********** program ********* class Program { public static void Main(string[] args) { var fooSource = fooSourceFactory.Create(); var barsProcessor = barsProcessorFactory.Create(fooSource) // this will create BarsProcessor and perform all the necessary subscriptions fooSource.Run(); // this enters a loop of listening for Foo objects from the network and notifying about their arrival. } } Which one do you think is better? Exposing IObservable and making our components create new event streams from Rx operators, or defining our own publisher/subscriber interfaces and using Rx internally if needed? Here are some things to consider about the designs: In the first design the consumer of our interfaces has the whole power of Rx at his/her fingertips and can perform any Rx operators. One of us claims this is an advantage and the other claims that this is a drawback. The second design allows us to use any publisher/subscriber architecture under the hood. The first design ties us to Rx. If we wish to use the power of Rx, it requires more work in the second design because we need to translate the custom publisher/subscriber implementation to Rx and back. It requires writing glue code for every class that wishes to do some event processing.

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  • Best Practice - Removing item from generic collection in C#

    - by Matt Davis
    I'm using C# in Visual Studio 2008 with .NET 3.5. I have a generic dictionary that maps types of events to a generic list of subscribers. A subscriber can be subscribed to more than one event. private static Dictionary<EventType, List<ISubscriber>> _subscriptions; To remove a subscriber from the subscription list, I can use either of these two options. Option 1: ISubscriber subscriber; // defined elsewhere foreach (EventType event in _subscriptions.Keys) { if (_subscriptions[event].Contains(subscriber)) { _subscriptions[event].Remove(subscriber); } } Option 2: ISubscriber subscriber; // defined elsewhere foreach (EventType event in _subscriptions.Keys) { _subscriptions[event].Remove(subscriber); } I have two questions. First, notice that Option 1 checks for existence before removing the item, while Option 2 uses a brute force removal since Remove() does not throw an exception. Of these two, which is the preferred, "best-practice" way to do this? Second, is there another, "cleaner," more elegant way to do this, perhaps with a lambda expression or using a LINQ extension? I'm still getting acclimated to these two features. Thanks. EDIT Just to clarify, I realize that the choice between Options 1 and 2 is a choice of speed (Option 2) versus maintainability (Option 1). In this particular case, I'm not necessarily trying to optimize the code, although that is certainly a worthy consideration. What I'm trying to understand is if there is a generally well-established practice for doing this. If not, which option would you use in your own code?

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  • Get ID of the object saved with association

    - by Pravin
    Hi, Here is my scenario: I have three models Subscriber, Subscription, Plan, with has_many :through relationship between Subscriber and Plans. A subscriber can have multiple plans with one active plan. Whenever a subscriber selects a plan I save it using accepts_nested_attributes_for :subscriptions. I get one plan from the form. Now my problem is I want to get the ID of the record created in subscriptions table.

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  • Hosting an NServiceBus subscriber in the same application as the producer.

    - by Jack Ryan
    Is it possible to use NServiceBus to publish and consume messages in the same application, specifically a web application? In the future we will almost certainly need to maintain a separate long running service to process messages generated by this application, and this is why we are hoping to use NServiceBus from the start, but right now it would be nice to just start up the consumer and the publisher when the web application starts. This will make testing and deployment far easier for us. I presume I will need to reference the NServiceBus.Host.exe and start up the process in the global.asax, but need help on what exactly I need to call to do this.

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  • How can I force a subscriber to be synchronized from a local snapshot?

    - by Brian
    Hello, I have a SQL 2005 server replicating(merge\push) to SQL 2005 and SQL 2000 servers. I have multiple subscribers spread througout the United states. I have set , @snapshot_in_defaultfolder = N'false', @alt_snapshot_folder = N'c:\snapshots\Merge\' (sample location). I take the snapshot from the publisher that is in the same location, 'c:\snapshots\Merge\', and copy it to the subscribers. I wanted to avoid applying the snapshot over the WAN but from the performance I am getting the synchronization is going over the WAN. Does anybody have any ideas how to make sure that I am using the local copy of the snapshot and not the copy at the publisher? Thanks

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  • Replication Services in a BI environment

    - by jorg
    In this blog post I will explain the principles of SQL Server Replication Services without too much detail and I will take a look on the BI capabilities that Replication Services could offer in my opinion. SQL Server Replication Services provides tools to copy and distribute database objects from one database system to another and maintain consistency afterwards. These tools basically copy or synchronize data with little or no transformations, they do not offer capabilities to transform data or apply business rules, like ETL tools do. The only “transformations” Replication Services offers is to filter records or columns out of your data set. You can achieve this by selecting the desired columns of a table and/or by using WHERE statements like this: SELECT <published_columns> FROM [Table] WHERE [DateTime] >= getdate() - 60 There are three types of replication: Transactional Replication This type replicates data on a transactional level. The Log Reader Agent reads directly on the transaction log of the source database (Publisher) and clones the transactions to the Distribution Database (Distributor), this database acts as a queue for the destination database (Subscriber). Next, the Distribution Agent moves the cloned transactions that are stored in the Distribution Database to the Subscriber. The Distribution Agent can either run at scheduled intervals or continuously which offers near real-time replication of data! So for example when a user executes an UPDATE statement on one or multiple records in the publisher database, this transaction (not the data itself) is copied to the distribution database and is then also executed on the subscriber. When the Distribution Agent is set to run continuously this process runs all the time and transactions on the publisher are replicated in small batches (near real-time), when it runs on scheduled intervals it executes larger batches of transactions, but the idea is the same. Snapshot Replication This type of replication makes an initial copy of database objects that need to be replicated, this includes the schemas and the data itself. All types of replication must start with a snapshot of the database objects from the Publisher to initialize the Subscriber. Transactional replication need an initial snapshot of the replicated publisher tables/objects to run its cloned transactions on and maintain consistency. The Snapshot Agent copies the schemas of the tables that will be replicated to files that will be stored in the Snapshot Folder which is a normal folder on the file system. When all the schemas are ready, the data itself will be copied from the Publisher to the snapshot folder. The snapshot is generated as a set of bulk copy program (BCP) files. Next, the Distribution Agent moves the snapshot to the Subscriber, if necessary it applies schema changes first and copies the data itself afterwards. The application of schema changes to the Subscriber is a nice feature, when you change the schema of the Publisher with, for example, an ALTER TABLE statement, that change is propagated by default to the Subscriber(s). Merge Replication Merge replication is typically used in server-to-client environments, for example when subscribers need to receive data, make changes offline, and later synchronize changes with the Publisher and other Subscribers, like with mobile devices that need to synchronize one in a while. Because I don’t really see BI capabilities here, I will not explain this type of replication any further. Replication Services in a BI environment Transactional Replication can be very useful in BI environments. In my opinion you never want to see users to run custom (SSRS) reports or PowerPivot solutions directly on your production database, it can slow down the system and can cause deadlocks in the database which can cause errors. Transactional Replication can offer a read-only, near real-time database for reporting purposes with minimal overhead on the source system. Snapshot Replication can also be useful in BI environments, if you don’t need a near real-time copy of the database, you can choose to use this form of replication. Next to an alternative for Transactional Replication it can be used to stage data so it can be transformed and moved into the data warehousing environment afterwards. In many solutions I have seen developers create multiple SSIS packages that simply copies data from one or more source systems to a staging database that figures as source for the ETL process. The creation of these packages takes a lot of (boring) time, while Replication Services can do the same in minutes. It is possible to filter out columns and/or records and it can even apply schema changes automatically so I think it offers enough features here. I don’t know how the performance will be and if it really works as good for this purpose as I expect, but I want to try this out soon!

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  • SQL 2008 Replication over Internet

    - by Akash Kava
    We have decided to put our servers in data centers on east and west coast of US, to keep high level redundancy. After evaluating number of replication options, apart from VPN there is no other way to do replication for SQL Server. We are investigating VPN but I have following questions. Our Large DB consists of media information (pictures/movies/audio/pdf) etc, so we are not very concerned about security because they are not financial sensitive data. SQL 2005 supports or can be configured to support replication over internet? If Yes then should we downgrade to 2005? If SQL 2008 Publisher is configured for Web Sync, can we write an automatic program (C# Windows Service) to act as pull subscriber and run on the subscriber server and replicate subscriber database? Or are there any API available in SQL where we can write our own program to do replication in very generic way? (In a nut shell, can we write our own C# Windows Service based Subscriber program?)

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  • SQL Server 2008 Replication Promotion

    - by Stefan Mai
    I have a 4 node cluster, 1 subscriber and 3 publishers, all running SQL Server 2008 R2 Enterprise. The intention is that if the subscriber goes down, we can use one of the publishers to quickly build up its replacement. Our testing reveals a problem though: the subcriber databases all have Not For Replication set to Yes on the identity columns so that they can maintain the identity set in the subscriber. This causes a problem when they become subscribers because now we don't have identity insert functionality: we get a primary key error. Any way to "promote" a subscriber to publisher?

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  • Optimized Publish/Subcribe JMS Broker Cluster and Conflicting Posts on StackOverFlow for the Answer

    - by Gene
    Hi, I am looking to build a publish/subscribe distributed messaging framework that can manage huge volumes of message traffic with some intelligence at the broker level. I don't know if there's a topology that describes this, but this is the model I'm going after: EXAMPLE MODEL A A) There are two running message brokers (ideally all on localhost if possible, for easier demo-ing) : Broker-A Broker-B B) Each broker will have 2 listeners and 1 publisher. Example Figure [subscriber A1, subscriber A2, publisher A1] <-- BrokerA <-- BrokerB <-- [publisher B1, subscriber B1, subscriber B2] IF a message-X is published to broker A and there no subscribers for it among the listeners on Broker-B (via criteria in Message Selectors or Broker routing rules), then that message-X will never be published to Broker-B. ELSE, broker A will publish the message to broker B, where one of the broker B listeners/subscribers/services is expecting that message based on the subscription criteria. Is Clustering the Correct Approach? At first, I concluded that the "Broker Clustering" concept is what I needed to support this. However, as I have come to understand it, the typical use of clustering entails either: message redundancy across all brokers ... or Competing Consumers pattern ... and neither of these satisfy the requirement in the EXAMPLE MODEL A. What is the Correct Approach? My question is, does anyone know of a JMS implementation that supports the model I described? I scanned through all the stackoverflow post titles for the search: JMS and Cluster. I found these two informative, but seemingly conflicting posts: Says the EXAMPLE MODEL A is/should-be implicitly supported: http://stackoverflow.com/questions/2255816/jms-consumer-with-activemq-network-of-brokers " this means you pick a broker, connect to it, and let the broker network sort it out amongst themselves. In theory." Says the EXAMPLE MODEL A IS NOT suported: http://stackoverflow.com/questions/2017520/how-does-a-jms-topic-subscriber-in-a-clustered-application-server-recieve-message "All the instances of PropertiesSubscriber running on different app servers WILL get that message." Any suggestions would be greatly appreciated. Thanks very much for reading my post, Gene

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  • Writing a JMS Publisher without "public static void main"

    - by The Elite Gentleman
    Hi guys, Every example I've seen on the web, e.g. http://www.codeproject.com/KB/docview/jms_to_jms_bridge_activem.aspx, creates a publisher and subscriber with a public static void main method. I don't think that'll work for my web application. I'm learning JMS and I've setup Apache ActiveMQ to run on JBoss 5 and Tomcat 6 (with no glitches). I'm writing a messaging JMS service that needs to send email asynchronously. I've already written a JMS subscriber that receives the message (the class inherits MessageListener). My question is simple: How do I write a publisher that will so that my web applications can call it? Does it have to be published somewhere? My thought is to create a publisher with a no-attribute constructor (in there) and get the MessageQueue Factory, etc. from the JNDI pool (in the constructor). Is my idea correct? How do I subscribe my subscriber to the Queue Receiver? (So far, the subscriber has no constructor, and if I write a constructor, do I always subscribe myself to the Queue receiver?) Thanks for your help, sorry if my terminology is not up to scratch, there are too many java terminologies that I get lost sometimes (maybe a java GPS will do! :-) ) PS Is there a tutorial out there that explains how to write a "better" (better can mean anything, but in my case it's all about performance in high demand requests) JMS Publisher and Subscriber that I can run on Application Server such as JBoss or Glassfish? Don't forget that the JMS application will needs a "guarantee" uptime as many applications will use this.

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