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• Work Item Visualizer for TFS 2010 - New Extension

  - by MikeParks

  I released another new extension to the Visual Studio Gallery again today called Work Item Visualizer for TFS 2010. I've only heard positive things about it so far, hopefully it stays that way :) Basically, it creates a diagram of all work items linked to a work item ID which the user specifies in a search box. This extension was coded using DGML (the same graph rendering language used for the Visual Studio 2010 Architecture Tools). It was pretty cool getting a chance to create something using some of the newest technology out there. Well, I just wanted to throw a blog up to get the word out on it a little more. If you're using Visual Studio 2010 with Team Foundation Server 2010, feel free to check it out! Thanks everyone. Download Link: http://visualstudiogallery.msdn.microsoft.com/en-us/a35b6010-750b-47f6-a7a5-41f0fa7294d2   What it does: ·         Creates a DGML graph to visualize linked TFS Work Items by entering a Work Item ID in the toolbar search box   How it benefits you: ·         Allows you to easily analyze the hierarchy of your TFS Work Items ·         Gain the ability to perform basic risk/impact analysis when creating or editing Work Items ·         Great for meetings in the case that you need to discuss the entire scope of linked Work Items ·         Easier project planning ·         Eliminates the need to create TFS queries or reports to view tree of Work Items ·         Easily lets you see the entire tree of work items linked to the one you’re working on   Navigation Tips: ·         Use Ctrl + Mouse Wheel Scroll to zoom in and out ·         Use Ctrl + Left Mouse click (and hold) to move document around ·         Right click on DGML area for more options (Like copy image or viewing in groups) ·         Clicking on each node highlights that node and the links connected to it ·         Colors in the legend can be changed ·         When work item nodes are deleted, the view is automatically updated ·         Double clicking on work item node will open up the Work Items URL   Try it out on work items that have several of links and let us know what you think. A big thanks goes out to everyone working on the http://visualization.codeplex.com/ project for publishing the source code on CodePlex which really helped me learn how DGML (Directed Graph Markup Language - New to Visual Studio 2010 Architecture Tools) works!    - Mike

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• Inside the Concurrent Collections: ConcurrentBag

  - by Simon Cooper

  Unlike the other concurrent collections, ConcurrentBag does not really have a non-concurrent analogy. As stated in the MSDN documentation, ConcurrentBag is optimised for the situation where the same thread is both producing and consuming items from the collection. We'll see how this is the case as we take a closer look. Again, I recommend you have ConcurrentBag open in a decompiler for reference. Thread Statics ConcurrentBag makes heavy use of thread statics - static variables marked with ThreadStaticAttribute. This is a special attribute that instructs the CLR to scope any values assigned to or read from the variable to the executing thread, not globally within the AppDomain. This means that if two different threads assign two different values to the same thread static variable, one value will not overwrite the other, and each thread will see the value they assigned to the variable, separately to any other thread. This is a very useful function that allows for ConcurrentBag's concurrency properties. You can think of a thread static variable: [ThreadStatic] private static int m_Value; as doing the same as: private static Dictionary<Thread, int> m_Values; where the executing thread's identity is used to automatically set and retrieve the corresponding value in the dictionary. In .NET 4, this usage of ThreadStaticAttribute is encapsulated in the ThreadLocal class. Lists of lists ConcurrentBag, at its core, operates as a linked list of linked lists: Each outer list node is an instance of ThreadLocalList, and each inner list node is an instance of Node. Each outer ThreadLocalList is owned by a particular thread, accessible through the thread local m_locals variable: private ThreadLocal<ThreadLocalList<T>> m_locals It is important to note that, although the m_locals variable is thread-local, that only applies to accesses through that variable. The objects referenced by the thread (each instance of the ThreadLocalList object) are normal heap objects that are not specific to any thread. Thinking back to the Dictionary analogy above, if each value stored in the dictionary could be accessed by other means, then any thread could access the value belonging to other threads using that mechanism. Only reads and writes to the variable defined as thread-local are re-routed by the CLR according to the executing thread's identity. So, although m_locals is defined as thread-local, the m_headList, m_nextList and m_tailList variables aren't. This means that any thread can access all the thread local lists in the collection by doing a linear search through the outer linked list defined by these variables. Adding items So, onto the collection operations. First, adding items. This one's pretty simple. If the current thread doesn't already own an instance of ThreadLocalList, then one is created (or, if there are lists owned by threads that have stopped, it takes control of one of those). Then the item is added to the head of that thread's list. That's it. Don't worry, it'll get more complicated when we account for the other operations on the list! Taking & Peeking items This is where it gets tricky. If the current thread's list has items in it, then it peeks or removes the head item (not the tail item) from the local list and returns that. However, if the local list is empty, it has to go and steal another item from another list, belonging to a different thread. It iterates through all the thread local lists in the collection using the m_headList and m_nextList variables until it finds one that has items in it, and it steals one item from that list. Up to this point, the two threads had been operating completely independently. To steal an item from another thread's list, the stealing thread has to do it in such a way as to not step on the owning thread's toes. Recall how adding and removing items both operate on the head of the thread's linked list? That gives us an easy way out - a thread trying to steal items from another thread can pop in round the back of another thread's list using the m_tail variable, and steal an item from the back without the owning thread knowing anything about it. The owning thread can carry on completely independently, unaware that one of its items has been nicked. However, this only works when there are at least 3 items in the list, as that guarantees there will be at least one node between the owning thread performing operations on the list head and the thread stealing items from the tail - there's no chance of the two threads operating on the same node at the same time and causing a race condition. If there's less than three items in the list, then there does need to be some synchronization between the two threads. In this case, the lock on the ThreadLocalList object is used to mediate access to a thread's list when there's the possibility of contention. Thread synchronization In ConcurrentBag, this is done using several mechanisms: Operations performed by the owner thread only take out the lock when there are less than three items in the collection. With three or greater items, there won't be any conflict with a stealing thread operating on the tail of the list. If a lock isn't taken out, the owning thread sets the list's m_currentOp variable to a non-zero value for the duration of the operation. This indicates to all other threads that there is a non-locked operation currently occuring on that list. The stealing thread always takes out the lock, to prevent two threads trying to steal from the same list at the same time. After taking out the lock, the stealing thread spinwaits until m_currentOp has been set to zero before actually performing the steal. This ensures there won't be a conflict with the owning thread when the number of items in the list is on the 2-3 item borderline. If any add or remove operations are started in the meantime, and the list is below 3 items, those operations try to take out the list's lock and are blocked until the stealing thread has finished. This allows a thread to steal an item from another thread's list without corrupting it. What about synchronization in the collection as a whole? Collection synchronization Any thread that operates on the collection's global structure (accessing anything outside the thread local lists) has to take out the collection's global lock - m_globalListsLock. This single lock is sufficient when adding a new thread local list, as the items inside each thread's list are unaffected. However, what about operations (such as Count or ToArray) that need to access every item in the collection? In order to ensure a consistent view, all operations on the collection are stopped while the count or ToArray is performed. This is done by freezing the bag at the start, performing the global operation, and unfreezing at the end: The global lock is taken out, to prevent structural alterations to the collection. m_needSync is set to true. This notifies all the threads that they need to take out their list's lock irregardless of what operation they're doing. All the list locks are taken out in order. This blocks all locking operations on the lists. The freezing thread waits for all current lockless operations to finish by spinwaiting on each m_currentOp field. The global operation can then be performed while the bag is frozen, but no other operations can take place at the same time, as all other threads are blocked on a list's lock. Then, once the global operation has finished, the locks are released, m_needSync is unset, and normal concurrent operation resumes. Concurrent principles That's the essence of how ConcurrentBag operates. Each thread operates independently on its own local list, except when they have to steal items from another list. When stealing, only the stealing thread is forced to take out the lock; the owning thread only has to when there is the possibility of contention. And a global lock controls accesses to the structure of the collection outside the thread lists. Operations affecting the entire collection take out all locks in the collection to freeze the contents at a single point in time. So, what principles can we extract here? Threads operate independently Thread-static variables and ThreadLocal makes this easy. Threads operate entirely concurrently on their own structures; only when they need to grab data from another thread is there any thread contention. Minimised lock-taking Even when two threads need to operate on the same data structures (one thread stealing from another), they do so in such a way such that the probability of actually blocking on a lock is minimised; the owning thread always operates on the head of the list, and the stealing thread always operates on the tail. Management of lockless operations Any operations that don't take out a lock still have a 'hook' to force them to lock when necessary. This allows all operations on the collection to be stopped temporarily while a global snapshot is taken. Hopefully, such operations will be short-lived and infrequent. That's all the concurrent collections covered. I hope you've found it as informative and interesting as I have. Next, I'll be taking a closer look at ThreadLocal, which I came across while analyzing ConcurrentBag. As you'll see, the operation of this class deserves a much closer look.

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• Multiplayer Network Game - Interpolation and Frame Rate

  - by J.C.

  Consider the following scenario: Let's say, for sake of example and simplicity, that you have an authoritative game server that sends state to its clients every 45ms. The clients are interpolating state with an interpolation delay of 100 ms. Finally, the clients are rendering a new frame every 15ms. When state is updated on the client, the client time is set from the incoming state update. Each time a frame renders, we take the render time (client time - interpolation delay) and identify a previous and target state to interpolate from. To calculate the interpolation amount/factor, we take the difference of the render time and previous state time and divide by the difference of the target state and previous state times: var factor = ((renderTime - previousStateTime) / (targetStateTime - previousStateTime)) Problem: In the example above, we are effectively displaying the same interpolated state for 3 frames before we collected the next server update and a new client (render) time is set. The rendering is mostly smooth, but there is a dash of jaggedness to it. Question: Given the example above, I'd like to think that the interpolation amount/factor should increase with each frame render to smooth out the movement. Should this be considered and, if so, what is the best way to achieve this given the information from above?

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• design an extendible and pluggable business logic flow handler in php

  - by Broncha

  I am working on a project where I need to allow a pluggable way to inject business processes in the normal data flow. eg There is an ordering system. The standard flow of the application is A consumer orders an item. Pays for it and card is authorized. Admin captures the payment. Order is marked as complete and item is shipped. But this process may vary (extra steps in between) for different clients. Say a client would need to validate the location of the consumer before he is presented with a credit card form, OR his policies might require some other processes in between. I am thinking of using State Pattern for processing orders, saving the current state of the order in database, and initializing the state of order from the saved state. I would also need some mechanism, where a small plugin would be able to inject business specific states in the state machine. Am I thinking the right way? Are there already implemented patterns for this kind of situation? I am working with Codeigniter and basically this would mean for me, to redirect to proper controller according to the current state of the order. Like, if the state of the order is unconfirmed then redirect the user to details page and then change the state to pending. If some client would need to do some validation, then register an intermediate state between unconfirmed and pending Please suggest.

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• Service Discovery in WCF 4.0 &ndash; Part 1

  - by Shaun

  When designing a service oriented architecture (SOA) system, there will be a lot of services with many service contracts, endpoints and behaviors. Besides the client calling the service, in a large distributed system a service may invoke other services. In this case, one service might need to know the endpoints it invokes. This might not be a problem in a small system. But when you have more than 10 services this might be a problem. For example in my current product, there are around 10 services, such as the user authentication service, UI integration service, location service, license service, device monitor service, event monitor service, schedule job service, accounting service, player management service, etc..   Benefit of Discovery Service Since almost all my services need to invoke at least one other service. This would be a difficult task to make sure all services endpoints are configured correctly in every service. And furthermore, it would be a nightmare when a service changed its endpoint at runtime. Hence, we need a discovery service to remove the dependency (configuration dependency). A discovery service plays as a service dictionary which stores the relationship between the contracts and the endpoints for every service. By using the discovery service, when service X wants to invoke service Y, it just need to ask the discovery service where is service Y, then the discovery service will return all proper endpoints of service Y, then service X can use the endpoint to send the request to service Y. And when some services changed their endpoint address, all need to do is to update its records in the discovery service then all others will know its new endpoint. In WCF 4.0 Discovery it supports both managed proxy discovery mode and ad-hoc discovery mode. In ad-hoc mode there is no standalone discovery service. When a client wanted to invoke a service, it will broadcast an message (normally in UDP protocol) to the entire network with the service match criteria. All services which enabled the discovery behavior will receive this message and only those matched services will send their endpoint back to the client. The managed proxy discovery service works as I described above. In this post I will only cover the managed proxy mode, where there’s a discovery service. For more information about the ad-hoc mode please refer to the MSDN.   Service Announcement and Probe The main functionality of discovery service should be return the proper endpoint addresses back to the service who is looking for. In most cases the consume service (as a client) will send the contract which it wanted to request to the discovery service. And then the discovery service will find the endpoint and respond. Sometimes the contract and endpoint are not enough. It also contains versioning, extensions attributes. This post I will only cover the case includes contract and endpoint. When a client (or sometimes a service who need to invoke another service) need to connect to a target service, it will firstly request the discovery service through the “Probe” method with the criteria. Basically the criteria contains the contract type name of the target service. Then the discovery service will search its endpoint repository by the criteria. The repository might be a database, a distributed cache or a flat XML file. If it matches, the discovery service will grab the endpoint information (it’s called discovery endpoint metadata in WCF) and send back. And this is called “Probe”. Finally the client received the discovery endpoint metadata and will use the endpoint to connect to the target service. Besides the probe, discovery service should take the responsible to know there is a new service available when it goes online, as well as stopped when it goes offline. This feature is named “Announcement”. When a service started and stopped, it will announce to the discovery service. So the basic functionality of a discovery service should includes: 1, An endpoint which receive the service online message, and add the service endpoint information in the discovery repository. 2, An endpoint which receive the service offline message, and remove the service endpoint information from the discovery repository. 3, An endpoint which receive the client probe message, and return the matches service endpoints, and return the discovery endpoint metadata. WCF 4.0 discovery service just covers all these features in it's infrastructure classes.   Discovery Service in WCF 4.0 WCF 4.0 introduced a new assembly named System.ServiceModel.Discovery which has all necessary classes and interfaces to build a WS-Discovery compliant discovery service. It supports ad-hoc and managed proxy modes. For the case mentioned in this post, what we need to build is a standalone discovery service, which is the managed proxy discovery service mode. To build a managed discovery service in WCF 4.0 just create a new class inherits from the abstract class System.ServiceModel.Discovery.DiscoveryProxy. This class implemented and abstracted the procedures of service announcement and probe. And it exposes 8 abstract methods where we can implement our own endpoint register, unregister and find logic. These 8 methods are asynchronized, which means all invokes to the discovery service are asynchronously, for better service capability and performance. 1, OnBeginOnlineAnnouncement, OnEndOnlineAnnouncement: Invoked when a service sent the online announcement message. We need to add the endpoint information to the repository in this method. 2, OnBeginOfflineAnnouncement, OnEndOfflineAnnouncement: Invoked when a service sent the offline announcement message. We need to remove the endpoint information from the repository in this method. 3, OnBeginFind, OnEndFind: Invoked when a client sent the probe message that want to find the service endpoint information. We need to look for the proper endpoints by matching the client’s criteria through the repository in this method. 4, OnBeginResolve, OnEndResolve: Invoked then a client sent the resolve message. Different from the find method, when using resolve method the discovery service will return the exactly one service endpoint metadata to the client. In our example we will NOT implement this method.   Let’s create our own discovery service, inherit the base System.ServiceModel.Discovery.DiscoveryProxy. We also need to specify the service behavior in this class. Since the build-in discovery service host class only support the singleton mode, we must set its instance context mode to single. 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5: using System.ServiceModel.Discovery; 6: using System.ServiceModel; 7:  8: namespace Phare.Service 9: { 10: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)] 11: public class ManagedProxyDiscoveryService : DiscoveryProxy 12: { 13: protected override IAsyncResult OnBeginFind(FindRequestContext findRequestContext, AsyncCallback callback, object state) 14: { 15: throw new NotImplementedException(); 16: } 17:  18: protected override IAsyncResult OnBeginOfflineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 19: { 20: throw new NotImplementedException(); 21: } 22:  23: protected override IAsyncResult OnBeginOnlineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 24: { 25: throw new NotImplementedException(); 26: } 27:  28: protected override IAsyncResult OnBeginResolve(ResolveCriteria resolveCriteria, AsyncCallback callback, object state) 29: { 30: throw new NotImplementedException(); 31: } 32:  33: protected override void OnEndFind(IAsyncResult result) 34: { 35: throw new NotImplementedException(); 36: } 37:  38: protected override void OnEndOfflineAnnouncement(IAsyncResult result) 39: { 40: throw new NotImplementedException(); 41: } 42:  43: protected override void OnEndOnlineAnnouncement(IAsyncResult result) 44: { 45: throw new NotImplementedException(); 46: } 47:  48: protected override EndpointDiscoveryMetadata OnEndResolve(IAsyncResult result) 49: { 50: throw new NotImplementedException(); 51: } 52: } 53: } Then let’s implement the online, offline and find methods one by one. WCF discovery service gives us full flexibility to implement the endpoint add, remove and find logic. For the demo purpose we will use an internal dictionary to store the services’ endpoint metadata. In the next post we will see how to serialize and store these information in database. Define a concurrent dictionary inside the service class since our it will be used in the multiple threads scenario. 1: [ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)] 2: public class ManagedProxyDiscoveryService : DiscoveryProxy 3: { 4: private ConcurrentDictionary<EndpointAddress, EndpointDiscoveryMetadata> _services; 5:  6: public ManagedProxyDiscoveryService() 7: { 8: _services = new ConcurrentDictionary<EndpointAddress, EndpointDiscoveryMetadata>(); 9: } 10: } Then we can simply implement the logic of service online and offline. 1: protected override IAsyncResult OnBeginOnlineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 2: { 3: _services.AddOrUpdate(endpointDiscoveryMetadata.Address, endpointDiscoveryMetadata, (key, value) => endpointDiscoveryMetadata); 4: return new OnOnlineAnnouncementAsyncResult(callback, state); 5: } 6:  7: protected override void OnEndOnlineAnnouncement(IAsyncResult result) 8: { 9: OnOnlineAnnouncementAsyncResult.End(result); 10: } 11:  12: protected override IAsyncResult OnBeginOfflineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state) 13: { 14: EndpointDiscoveryMetadata endpoint = null; 15: _services.TryRemove(endpointDiscoveryMetadata.Address, out endpoint); 16: return new OnOfflineAnnouncementAsyncResult(callback, state); 17: } 18:  19: protected override void OnEndOfflineAnnouncement(IAsyncResult result) 20: { 21: OnOfflineAnnouncementAsyncResult.End(result); 22: } Regards the find method, the parameter FindRequestContext.Criteria has a method named IsMatch, which can be use for us to evaluate which service metadata is satisfied with the criteria. So the implementation of find method would be like this. 1: protected override IAsyncResult OnBeginFind(FindRequestContext findRequestContext, AsyncCallback callback, object state) 2: { 3: _services.Where(s => findRequestContext.Criteria.IsMatch(s.Value)) 4: .Select(s => s.Value) 5: .All(meta => 6: { 7: findRequestContext.AddMatchingEndpoint(meta); 8: return true; 9: }); 10: return new OnFindAsyncResult(callback, state); 11: } 12:  13: protected override void OnEndFind(IAsyncResult result) 14: { 15: OnFindAsyncResult.End(result); 16: } As you can see, we checked all endpoints metadata in repository by invoking the IsMatch method. Then add all proper endpoints metadata into the parameter. Finally since all these methods are asynchronized we need some AsyncResult classes as well. Below are the base class and the inherited classes used in previous methods. 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5: using System.Threading; 6:  7: namespace Phare.Service 8: { 9: abstract internal class AsyncResult : IAsyncResult 10: { 11: AsyncCallback callback; 12: bool completedSynchronously; 13: bool endCalled; 14: Exception exception; 15: bool isCompleted; 16: ManualResetEvent manualResetEvent; 17: object state; 18: object thisLock; 19:  20: protected AsyncResult(AsyncCallback callback, object state) 21: { 22: this.callback = callback; 23: this.state = state; 24: this.thisLock = new object(); 25: } 26:  27: public object AsyncState 28: { 29: get 30: { 31: return state; 32: } 33: } 34:  35: public WaitHandle AsyncWaitHandle 36: { 37: get 38: { 39: if (manualResetEvent != null) 40: { 41: return manualResetEvent; 42: } 43: lock (ThisLock) 44: { 45: if (manualResetEvent == null) 46: { 47: manualResetEvent = new ManualResetEvent(isCompleted); 48: } 49: } 50: return manualResetEvent; 51: } 52: } 53:  54: public bool CompletedSynchronously 55: { 56: get 57: { 58: return completedSynchronously; 59: } 60: } 61:  62: public bool IsCompleted 63: { 64: get 65: { 66: return isCompleted; 67: } 68: } 69:  70: object ThisLock 71: { 72: get 73: { 74: return this.thisLock; 75: } 76: } 77:  78: protected static TAsyncResult End<TAsyncResult>(IAsyncResult result) 79: where TAsyncResult : AsyncResult 80: { 81: if (result == null) 82: { 83: throw new ArgumentNullException("result"); 84: } 85:  86: TAsyncResult asyncResult = result as TAsyncResult; 87:  88: if (asyncResult == null) 89: { 90: throw new ArgumentException("Invalid async result.", "result"); 91: } 92:  93: if (asyncResult.endCalled) 94: { 95: throw new InvalidOperationException("Async object already ended."); 96: } 97:  98: asyncResult.endCalled = true; 99:  100: if (!asyncResult.isCompleted) 101: { 102: asyncResult.AsyncWaitHandle.WaitOne(); 103: } 104:  105: if (asyncResult.manualResetEvent != null) 106: { 107: asyncResult.manualResetEvent.Close(); 108: } 109:  110: if (asyncResult.exception != null) 111: { 112: throw asyncResult.exception; 113: } 114:  115: return asyncResult; 116: } 117:  118: protected void Complete(bool completedSynchronously) 119: { 120: if (isCompleted) 121: { 122: throw new InvalidOperationException("This async result is already completed."); 123: } 124:  125: this.completedSynchronously = completedSynchronously; 126:  127: if (completedSynchronously) 128: { 129: this.isCompleted = true; 130: } 131: else 132: { 133: lock (ThisLock) 134: { 135: this.isCompleted = true; 136: if (this.manualResetEvent != null) 137: { 138: this.manualResetEvent.Set(); 139: } 140: } 141: } 142:  143: if (callback != null) 144: { 145: callback(this); 146: } 147: } 148:  149: protected void Complete(bool completedSynchronously, Exception exception) 150: { 151: this.exception = exception; 152: Complete(completedSynchronously); 153: } 154: } 155: } 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5: using System.ServiceModel.Discovery; 6: using Phare.Service; 7:  8: namespace Phare.Service 9: { 10: internal sealed class OnOnlineAnnouncementAsyncResult : AsyncResult 11: { 12: public OnOnlineAnnouncementAsyncResult(AsyncCallback callback, object state) 13: : base(callback, state) 14: { 15: this.Complete(true); 16: } 17:  18: public static void End(IAsyncResult result) 19: { 20: AsyncResult.End<OnOnlineAnnouncementAsyncResult>(result); 21: } 22:  23: } 24:  25: sealed class OnOfflineAnnouncementAsyncResult : AsyncResult 26: { 27: public OnOfflineAnnouncementAsyncResult(AsyncCallback callback, object state) 28: : base(callback, state) 29: { 30: this.Complete(true); 31: } 32:  33: public static void End(IAsyncResult result) 34: { 35: AsyncResult.End<OnOfflineAnnouncementAsyncResult>(result); 36: } 37: } 38:  39: sealed class OnFindAsyncResult : AsyncResult 40: { 41: public OnFindAsyncResult(AsyncCallback callback, object state) 42: : base(callback, state) 43: { 44: this.Complete(true); 45: } 46:  47: public static void End(IAsyncResult result) 48: { 49: AsyncResult.End<OnFindAsyncResult>(result); 50: } 51: } 52:  53: sealed class OnResolveAsyncResult : AsyncResult 54: { 55: EndpointDiscoveryMetadata matchingEndpoint; 56:  57: public OnResolveAsyncResult(EndpointDiscoveryMetadata matchingEndpoint, AsyncCallback callback, object state) 58: : base(callback, state) 59: { 60: this.matchingEndpoint = matchingEndpoint; 61: this.Complete(true); 62: } 63:  64: public static EndpointDiscoveryMetadata End(IAsyncResult result) 65: { 66: OnResolveAsyncResult thisPtr = AsyncResult.End<OnResolveAsyncResult>(result); 67: return thisPtr.matchingEndpoint; 68: } 69: } 70: } Now we have finished the discovery service. The next step is to host it. The discovery service is a standard WCF service. So we can use ServiceHost on a console application, windows service, or in IIS as usual. The following code is how to host the discovery service we had just created in a console application. 1: static void Main(string[] args) 2: { 3: using (var host = new ServiceHost(new ManagedProxyDiscoveryService())) 4: { 5: host.Opened += (sender, e) => 6: { 7: host.Description.Endpoints.All((ep) => 8: { 9: Console.WriteLine(ep.ListenUri); 10: return true; 11: }); 12: }; 13:  14: try 15: { 16: // retrieve the announcement, probe endpoint and binding from configuration 17: var announcementEndpointAddress = new EndpointAddress(ConfigurationManager.AppSettings["announcementEndpointAddress"]); 18: var probeEndpointAddress = new EndpointAddress(ConfigurationManager.AppSettings["probeEndpointAddress"]); 19: var binding = Activator.CreateInstance(Type.GetType(ConfigurationManager.AppSettings["bindingType"], true, true)) as Binding; 20: var announcementEndpoint = new AnnouncementEndpoint(binding, announcementEndpointAddress); 21: var probeEndpoint = new DiscoveryEndpoint(binding, probeEndpointAddress); 22: probeEndpoint.IsSystemEndpoint = false; 23: // append the service endpoint for announcement and probe 24: host.AddServiceEndpoint(announcementEndpoint); 25: host.AddServiceEndpoint(probeEndpoint); 26:  27: host.Open(); 28:  29: Console.WriteLine("Press any key to exit."); 30: Console.ReadKey(); 31: } 32: catch (Exception ex) 33: { 34: Console.WriteLine(ex.ToString()); 35: } 36: } 37:  38: Console.WriteLine("Done."); 39: Console.ReadKey(); 40: } What we need to notice is that, the discovery service needs two endpoints for announcement and probe. In this example I just retrieve them from the configuration file. I also specified the binding of these two endpoints in configuration file as well. 1: <?xml version="1.0"?> 2: <configuration> 3: <startup> 4: <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/> 5: </startup> 6: <appSettings> 7: <add key="announcementEndpointAddress" value="net.tcp://localhost:10010/announcement"/> 8: <add key="probeEndpointAddress" value="net.tcp://localhost:10011/probe"/> 9: <add key="bindingType" value="System.ServiceModel.NetTcpBinding, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> 10: </appSettings> 11: </configuration> And this is the console screen when I ran my discovery service. As you can see there are two endpoints listening for announcement message and probe message.   Discoverable Service and Client Next, let’s create a WCF service that is discoverable, which means it can be found by the discovery service. To do so, we need to let the service send the online announcement message to the discovery service, as well as offline message before it shutdown. Just create a simple service which can make the incoming string to upper. The service contract and implementation would be like this. 1: [ServiceContract] 2: public interface IStringService 3: { 4: [OperationContract] 5: string ToUpper(string content); 6: } 1: public class StringService : IStringService 2: { 3: public string ToUpper(string content) 4: { 5: return content.ToUpper(); 6: } 7: } Then host this service in the console application. In order to make the discovery service easy to be tested the service address will be changed each time it’s started. 1: static void Main(string[] args) 2: { 3: var baseAddress = new Uri(string.Format("net.tcp://localhost:11001/stringservice/{0}/", Guid.NewGuid().ToString())); 4:  5: using (var host = new ServiceHost(typeof(StringService), baseAddress)) 6: { 7: host.Opened += (sender, e) => 8: { 9: Console.WriteLine("Service opened at {0}", host.Description.Endpoints.First().ListenUri); 10: }; 11:  12: host.AddServiceEndpoint(typeof(IStringService), new NetTcpBinding(), string.Empty); 13:  14: host.Open(); 15:  16: Console.WriteLine("Press any key to exit."); 17: Console.ReadKey(); 18: } 19: } Currently this service is NOT discoverable. We need to add a special service behavior so that it could send the online and offline message to the discovery service announcement endpoint when the host is opened and closed. WCF 4.0 introduced a service behavior named ServiceDiscoveryBehavior. When we specified the announcement endpoint address and appended it to the service behaviors this service will be discoverable. 1: var announcementAddress = new EndpointAddress(ConfigurationManager.AppSettings["announcementEndpointAddress"]); 2: var announcementBinding = Activator.CreateInstance(Type.GetType(ConfigurationManager.AppSettings["bindingType"], true, true)) as Binding; 3: var announcementEndpoint = new AnnouncementEndpoint(announcementBinding, announcementAddress); 4: var discoveryBehavior = new ServiceDiscoveryBehavior(); 5: discoveryBehavior.AnnouncementEndpoints.Add(announcementEndpoint); 6: host.Description.Behaviors.Add(discoveryBehavior); The ServiceDiscoveryBehavior utilizes the service extension and channel dispatcher to implement the online and offline announcement logic. In short, it injected the channel open and close procedure and send the online and offline message to the announcement endpoint.   On client side, when we have the discovery service, a client can invoke a service without knowing its endpoint. WCF discovery assembly provides a class named DiscoveryClient, which can be used to find the proper service endpoint by passing the criteria. In the code below I initialized the DiscoveryClient, specified the discovery service probe endpoint address. Then I created the find criteria by specifying the service contract I wanted to use and invoke the Find method. This will send the probe message to the discovery service and it will find the endpoints back to me. The discovery service will return all endpoints that matches the find criteria, which means in the result of the find method there might be more than one endpoints. In this example I just returned the first matched one back. In the next post I will show how to extend our discovery service to make it work like a service load balancer. 1: static EndpointAddress FindServiceEndpoint() 2: { 3: var probeEndpointAddress = new EndpointAddress(ConfigurationManager.AppSettings["probeEndpointAddress"]); 4: var probeBinding = Activator.CreateInstance(Type.GetType(ConfigurationManager.AppSettings["bindingType"], true, true)) as Binding; 5: var discoveryEndpoint = new DiscoveryEndpoint(probeBinding, probeEndpointAddress); 6:  7: EndpointAddress address = null; 8: FindResponse result = null; 9: using (var discoveryClient = new DiscoveryClient(discoveryEndpoint)) 10: { 11: result = discoveryClient.Find(new FindCriteria(typeof(IStringService))); 12: } 13:  14: if (result != null && result.Endpoints.Any()) 15: { 16: var endpointMetadata = result.Endpoints.First(); 17: address = endpointMetadata.Address; 18: } 19: return address; 20: } Once we probed the discovery service we will receive the endpoint. So in the client code we can created the channel factory from the endpoint and binding, and invoke to the service. When creating the client side channel factory we need to make sure that the client side binding should be the same as the service side. WCF discovery service can be used to find the endpoint for a service contract, but the binding is NOT included. This is because the binding was not in the WS-Discovery specification. In the next post I will demonstrate how to add the binding information into the discovery service. At that moment the client don’t need to create the binding by itself. Instead it will use the binding received from the discovery service. 1: static void Main(string[] args) 2: { 3: Console.WriteLine("Say something..."); 4: var content = Console.ReadLine(); 5: while (!string.IsNullOrWhiteSpace(content)) 6: { 7: Console.WriteLine("Finding the service endpoint..."); 8: var address = FindServiceEndpoint(); 9: if (address == null) 10: { 11: Console.WriteLine("There is no endpoint matches the criteria."); 12: } 13: else 14: { 15: Console.WriteLine("Found the endpoint {0}", address.Uri); 16:  17: var factory = new ChannelFactory<IStringService>(new NetTcpBinding(), address); 18: factory.Opened += (sender, e) => 19: { 20: Console.WriteLine("Connecting to {0}.", factory.Endpoint.ListenUri); 21: }; 22: var proxy = factory.CreateChannel(); 23: using (proxy as IDisposable) 24: { 25: Console.WriteLine("ToUpper: {0} => {1}", content, proxy.ToUpper(content)); 26: } 27: } 28:  29: Console.WriteLine("Say something..."); 30: content = Console.ReadLine(); 31: } 32: } Similarly, the discovery service probe endpoint and binding were defined in the configuration file. 1: <?xml version="1.0"?> 2: <configuration> 3: <startup> 4: <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/> 5: </startup> 6: <appSettings> 7: <add key="announcementEndpointAddress" value="net.tcp://localhost:10010/announcement"/> 8: <add key="probeEndpointAddress" value="net.tcp://localhost:10011/probe"/> 9: <add key="bindingType" value="System.ServiceModel.NetTcpBinding, System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/> 10: </appSettings> 11: </configuration> OK, now let’s have a test. Firstly start the discovery service, and then start our discoverable service. When it started it will announced to the discovery service and registered its endpoint into the repository, which is the local dictionary. And then start the client and type something. As you can see the client asked the discovery service for the endpoint and then establish the connection to the discoverable service. And more interesting, do NOT close the client console but terminate the discoverable service but press the enter key. This will make the service send the offline message to the discovery service. Then start the discoverable service again. Since we made it use a different address each time it started, currently it should be hosted on another address. If we enter something in the client we could see that it asked the discovery service and retrieve the new endpoint, and connect the the service.   Summary In this post I discussed the benefit of using the discovery service and the procedures of service announcement and probe. I also demonstrated how to leverage the WCF Discovery feature in WCF 4.0 to build a simple managed discovery service. For test purpose, in this example I used the in memory dictionary as the discovery endpoint metadata repository. And when finding I also just return the first matched endpoint back. I also hard coded the bindings between the discoverable service and the client. In next post I will show you how to solve the problem mentioned above, as well as some additional feature for production usage. You can download the code here.   Hope this helps, Shaun All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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• Use Dojo Drag and Drop together with Dojo Moveable

  - by Select0r

  Hi, I'm using Dojo.dnd to transfer items between to areas. The problem is: the items will snap into place once I drop them, but I'd like to have them stay where I drop them, but only for one area. Here's a little code to explain this better: <div id="dropZone" class="dropZone"> <div id="itemNodes"></div> <div id="targetZone" dojoType="dojo.dnd.Source"></div> </div> "dropZone" is a DIV that contains two dojo.dnd.Source-areas, "itemNodes" (created programmatically) and "targetZone". Items (DIVs with images) should be dragged from a simple list out of "itemNodes" into "targetZone" and stay where they are dropped. As soon as they are dragged out of "targetZone" they should snap back to the list inside "itemNodes". Here's the code I use to create the items: var nodelist = new dojo.dnd.Source("itemNodes"); {Smarty-Loop} nodelist.insertNodes(false, ['<img class="dragItem" src="{$items->info.itemtext}" alt="{$items->info.itemtext}" border="0" />']); {/Smarty-Loop} But this way I just have two lists of items, the items dropped into "targetZone" won't stay where I dropped them. I've tried a loop dojo.query(".dojoDndItem").forEach(function(node) to grab all items and change them to a "moveable"-type: using dojo.dnd.move.constrainedMoveable will change the items so they can always be moved around (even in "itemNodes") using dojo.dnd.move.boxConstrainedMoveable and defining the "box" to the borders of "targetZone" makes it possible to just move the items around inside "targetZone", but as soon as I drop them, I can't grab and move them back out So here's the question: is it possible to create two dnd.Sources where I can move items back and forth and let the items be "moveable" only in one of the sources?Or is there a workaround like making the items moveable and if they're not dropped into "targetZone" they'll be moved back to the list in "itemNodes" automatically? Once the page is submitted, I have to save the position of every item that has been placed into "targetZone". (The next step will be positioning the items inside "targetZone" on page load if the grid has already been filled before, but I'd be happy to just get the thing working in the first place.) Any hint is appreciated. Greetings, Select0r

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• How can I line up WPF items in a Horizontal WrapPanel so they line up based on an arbitrary vertical

  - by Scott Whitlock

  I'm trying to create a View in WPF and having a hard time figuring out how to set it up. Here's what I'm trying to build: My ViewModel exposes an IEnumerable property called Items Each item is an event on a timeline, and each one implements ITimelineItem The ViewModel for each item has it's own DataTemplate to to display it I want to display all the items on the timeline connected by a line. I'm thinking a WrapPanel inside of a ListView would work well for this. However, the height of each item will vary depending on the information it displays. Some items will have graphic objects right on the line (like a circle or a diamond, or whatever), and some have annotations above or below the line. So it seems complicated to me. It seems that each item on the timeline has to render its own segment of the line. That's fine. But the distance between the top of the item to the line (and the bottom of the item to the line) could vary. If one item has the line 50 px down from the top and the next item has the line 100 px down from the top, then the first item needs 50 px of padding so that the line segments add up. I think I could solve that problem, however, we only need to add padding if these two items are on the same line in the WrapPanel! Let's say there are 5 items and only room on the screen for 3 across... the WrapPanel will put the other two on the next line. That's ok, but that means only the first 3 need to pad together, and the last 2 need to pad together. This is what's giving me a headache. Is there another approach I could look at?

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• Why is the ASP Repeater.Items collection empty, when controls are on the screen?

  - by Ryan

  I have an ASP page with the following repeater: <asp:Repeater runat="server" ID="RegionRepeater" DataSourceID="SqlDataSourceRegions" EnableViewState="true"> <ItemTemplate> <tr> <td valign="top"> <b><%#Eval("description")%></b> <asp:HiddenField runat="server" ID="RegionID" Value='<%#Eval("region_id")%>'/> </td> <td> <asp:FileUpload ID="FileUpload" runat="server" Width="368px" /> </td> </tr> </ItemTemplate> </asp:Repeater> (The repeater is inside a Wizard, inside a content pane). The code behind is connected to the protected void Wizard1_NextButtonClick(object sender, WizardNavigationEventArgs e) event. There are two items on the screen (two rows inside the table). However, when the code tries to read those items, the Items collection is empty! foreach(RepeaterItem region in RegionRepeater.Items) { // Never runs - the RegionRepeater.Items.Count = 0 FileUpload fileUpload = (FileUpload) region.FindControl("FileUpload"); String regionID = ((HiddenField)region.FindControl("RegionID")).Value; ... Why is the collection empty, when there are controls drawn on the screen? Thanks a lot for any help; this is starting to drive me nuts. (BTW: I tried adding/removing the EnableViewState="true" tag)

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• Pros and Cons of using ASP.NET Session State Server (instead of InProc)?

  - by jdk

  Before I start using Session State server for the benefit of making session state more robust in may apps compared to InProc state, I'd like to find a list of Pros and Cons for evaluation.

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• How do I Fix SQL Server error: Order by items must appear in the select list if Select distinct is s

  - by Paula DiTallo 2007-2009 All Rights Reserved

  There's more than one reason why you may receive this error, but the most common reason is that your order by statement column list doesn't correlate with the values specified in your column list when you happen to be using DISTINCT. This is usually easy to spot and resolve. A more obscure reason may be that you are using a function around one of the selected columns --but omitting to use the same function around the same selected column name in the order by statement. Here's an example:   select distinct upper(columnA)   from [evaluate].[testTable]    order by columnA  asc   This statement will cause the "Order by items must appear in the select list if SELECT DISTINCT is specified."  error to appear not because distinct was used, but because the order by statement did not utilize the upper() fundtion around colunnA.  To correct this error, do this: select distinct upper(columnA)   from [evaluate].[testTable]    order by upper(columnA) asc

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• How can I store spell & items using a std::vector implementation?

  - by Vladimir Marenus

  I'm following along with a book from GameInstitute right now, and it's asking me to: Allow the player to buy and carry healing potions and potions of fireball. You can add an Item array (after you define the item class) to the Player class for storing them, or use a std::vector to store them. I think I would like to use the std::vector implementation, because that seems to confuse me less than making an item class, but I am unsure how to do so. I've heard from many people that vectors are great ways to store dynamic values (such as items, weapons, etc), but I've not seen it used.

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• How to add multiple menu items with the same title to NSPopUpButton(NSMenu)?

  - by William S. Pear

  As docs say it's impossible to add two menu items to NSPopUpButton if they both have the same title. I was trying to add menu items to [popupButton menu], but with no luck. I was also trying to create a new menu, add items to it and then use [popupButton setMenu:newMenu], but no. Menu always display only one item per name. But I know it should be possible, if you try to create a smart playlist in iTunes, you could select "Playlist" from the left popup button, "=" from the middle, and the right one will hold menu items for every playlist in iTunes EVEN if they have the same title. So how do they do it?

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• What is the best way to construct a "remove multiple items" area (ASP.NET VB) [on hold]

  - by Darkcat Studios

  Lets say for example I have a (variable length) 2 dimensional array of product names and their unique product codes. I can display this list in a datagrid, table etc. (Imagine this as a standard shopping basket type scenario) What I need to do is be able to tick multiple items (?) , then on clicking a submit button, fire an action. The bit im struggling with is how do i: A: programatically display asp:checkboxes for each item (and give them a unique ID) B: know which are ticked on firing the final action (not sure if this question is best suited to the main stack but theres so much activity on there that questions just get lost now!)

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• Can I find out the number of searches on a given keyword, per state?

  - by Philippe

  I know that Google tells you how many times a certain keyword is used in a search. You can use the Google Keyword Tool for that. This tool also allows you to find out the number of "local" searches: this is the number of times a person from a given country searches for this keyword. My questions: can you also find out how many searches originate from a given American state ? In the Keyword Tool, I can only select countries, not states. Any other systems I can use to determine where people are searching for a given keyword?

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• What all items can I put on my resume without it looking tacky? [closed]

  - by Earlz

  I've been searching for work, and so far it's very hard for me to even get a call back. So, I'm looking at adding things to my resume. I know a resume doesn't need to be over 2 pages. I have the basics: Objective/personal info General skills (languages known, etc) Work experience Some things I'm considering adding to it: My college education (though I don't have a degree) Awards given for programming skills in high school (curriculum contests and AP test scores) Open source projects? Would any of these 3 items look tacky? And I only have about 1.5 years of work experience, but I've been programming since I was 13. Is there anything else I can add to my resume that would give me a better chance of getting my foot in the door?

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• How to remap Fn key combinations (Lenovo G500)

  - by Anatoli

  I am running Kubuntu 13.10 on a Lenovo G500 laptop. My question is similar to this one: How can I remap my F keys on my HP laptop? That is to say, my F1-F12 keys are mapped to certain special functions, and only holding down the Fn key restores access to the standard F1-F12 keys. How do I remap certain keys? I would like to know if there is a way to remap Fx to Fn+Fx and vice-versa. As per the instructions of #87043 I checked my BIOS and there is no option to switch the Fx/Fn key functionality. Googling through Leonovo's support forums indicates a BIOS update enabling this is in the works, but there's no indication of when it will be complete. Using xev I was able to see what X sees when F1-F12 are pressed. Some send separate keycodes, but some are somehow mapped to key combinations or other unknown things: F1 - XF86AudioMute F2 - XF86AudioVolumeLower F3 - XF86AudioVolumeRaise F4 - Alt_L + F4 F5 - F5 F6 - Disables touchapd, cannot quite understand what xev tells me is happening, reenables if disabled (Kernel log reveals these have well-defined scancodes not assigned to any keycodes) F7 - XF86WLAN F8 - Alt_L + Ctrl_L + Tab F9 - Turns off LCD backlight, xev sees nothing F10 - Super_L + p F11 - XF86MonBrightnessLower F12 - XF86MonBrightnessRaise Following the instrusctions on this page: How do I remap certain keys? I remapped all the keys that have definite keycodes (F1, F2, F3, F5, F7, F11, F12) This still leaves the F4, F6, F8, F9, F10 keys not functioning properly. This is especially frustarting since F4, F6, F9 now kill the current window, the touchpad and screen, respectively. Any help on remapping these keys to their proper functions would be much appreciated! -Anatoli xev output for these 5 keys: F4 KeyPress event, serial 40, synthetic NO, window 0x4800001, root 0x9d, subw 0x0, time 3674037, (228,298), root:(911,321), state 0x0, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False FocusOut event, serial 40, synthetic NO, window 0x4800001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 40, synthetic NO, window 0x4800001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 40, synthetic NO, window 0x0, keys: 4294967197 0 0 0 0 0 0 0 65 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 KeyRelease event, serial 40, synthetic NO, window 0x4800001, root 0x9d, subw 0x0, time 3674040, (228,298), root:(911,321), state 0x8, keycode 70 (keysym 0xffc1, F4), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4800001, root 0x9d, subw 0x0, time 3674042, (228,298), root:(911,321), state 0x8, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False ClientMessage event, serial 40, synthetic YES, window 0x4800001, message_type 0x12a (WM_PROTOCOLS), format 32, message 0x12b (WM_DELETE_WINDOW) F6 disabling touchpad MappingNotify event, serial 40, synthetic NO, window 0x0, request MappingKeyboard, first_keycode 8, count 248 FocusOut event, serial 40, synthetic NO, window 0x4600001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 40, synthetic NO, window 0x4600001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 40, synthetic NO, window 0x0, keys: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 MappingNotify event, serial 41, synthetic NO, window 0x0, request MappingKeyboard, first_keycode 8, count 248 F6 enabling touchpad MappingNotify event, serial 42, synthetic NO, window 0x0, request MappingKeyboard, first_keycode 8, count 248 FocusOut event, serial 42, synthetic NO, window 0x4600001, mode NotifyGrab, detail NotifyAncestor FocusIn event, serial 42, synthetic NO, window 0x4600001, mode NotifyUngrab, detail NotifyAncestor KeymapNotify event, serial 42, synthetic NO, window 0x0, keys: 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 MappingNotify event, serial 43, synthetic NO, window 0x0, request MappingPointer, first_keycode 0, count 0 F8 doing whatever it is F8 does KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508985, (13,-12), root:(696,11), state 0x0, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508986, (13,-12), root:(696,11), state 0x8, keycode 37 (keysym 0xffe3, Control_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508988, (13,-12), root:(696,11), state 0xc, keycode 23 (keysym 0xff09, Tab), same_screen YES, XLookupString gives 1 bytes: (09) " " XmbLookupString gives 1 bytes: (09) " " XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508989, (13,-12), root:(696,11), state 0xc, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508991, (13,-12), root:(696,11), state 0x4, keycode 37 (keysym 0xffe3, Control_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3508994, (13,-12), root:(696,11), state 0x0, keycode 23 (keysym 0xff09, Tab), same_screen YES, XLookupString gives 1 bytes: (09) " " XFilterEvent returns: False F9 gives no output to xev F10 doing whatever it is F10 does KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586076, (9,-14), root:(692,9), state 0x0, keycode 10 (keysym 0x31, 1), same_screen YES, XLookupString gives 1 bytes: (31) "1" XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586552, (9,-14), root:(692,9), state 0x0, keycode 133 (keysym 0xffeb, Super_L), same_screen YES, XLookupString gives 0 bytes: XmbLookupString gives 0 bytes: XFilterEvent returns: False KeyPress event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586554, (9,-14), root:(692,9), state 0x40, keycode 33 (keysym 0x70, p), same_screen YES, XLookupString gives 1 bytes: (70) "p" XmbLookupString gives 1 bytes: (70) "p" XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586557, (9,-14), root:(692,9), state 0x40, keycode 33 (keysym 0x70, p), same_screen YES, XLookupString gives 1 bytes: (70) "p" XFilterEvent returns: False KeyRelease event, serial 40, synthetic NO, window 0x4600001, root 0x9d, subw 0x0, time 3586560, (9,-14), root:(692,9), state 0x40, keycode 133 (keysym 0xffeb, Super_L), same_screen YES, XLookupString gives 0 bytes: XFilterEvent returns: False

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• Are there any tools to help the user to design a State Machine to be consumed by my application?

  - by kolrie

  When reading this question I remembered there was something I have been researching for a while now and I though Stackoverflow could be of help. I have created a framework that handles applications as state machines. Currently all the state business logic and transactions are handled via Java code. I was looking for some UI implementation that would allow the user to draw the state machines and transactions and generate a file that can later on be consumed by my framework to "run" the workflow according to one or more defined state machines. Ideally I would like to use an open standard like SCXML. The goal as the UI would be to have something like this plugin IBM have for Rational Software Architect: Do you know any editor, plugin or library that would have something similar or at least serve as a good starting point?

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• How can I create wpf Carousel withmy listview items?

  - by ashish semwal

  Hi All, I have horizontal wpf listview and i want to scroll all items on left/right button click. So that when i clicked on Prev/Left button listview items moves to left and on Right/Next button click listview items moves to right. Like jQuery Carousel

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• Could not connect to wireless unitl reboot (nl80211)

  - by user107410

  I'm using Samsung NP900X3C. I have problem with occasionally connecting to WIFI, with Ubuntu 12.10. Sometimes my computer could not connect to WIFI "blab", neither after reboot computer. Only solution is to restart WIFI hotspot. It's public WIFI, used by many users, that don't have that problem. My /var/log/syslog: Nov 12 10:09:39 k15 wpa_supplicant[1308]: wlan0: SME: Trying to authenticate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) Nov 12 10:09:39 k15 kernel: [ 8.908610] wlan0: authenticate with 64:70:02:89:7c:d7 Nov 12 10:09:39 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: scanning -> authenticating Nov 12 10:09:39 k15 kernel: [ 8.915032] wlan0: send auth to 64:70:02:89:7c:d7 (try 1/3) Nov 12 10:09:39 k15 wpa_supplicant[1308]: wlan0: Trying to associate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) Nov 12 10:09:39 k15 kernel: [ 8.916753] wlan0: authenticated Nov 12 10:09:39 k15 kernel: [ 8.916839] wlan0: waiting for beacon from 64:70:02:89:7c:d7 Nov 12 10:09:39 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: authenticating -> associating Nov 12 10:09:39 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: associating -> disconnected Nov 12 10:09:39 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: disconnected -> scanning Nov 12 10:09:42 k15 wpa_supplicant[1308]: wlan0: SME: Trying to authenticate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) Nov 12 10:09:42 k15 kernel: [ 12.386212] wlan0: authenticate with 64:70:02:89:7c:d7 Nov 12 10:09:42 k15 wpa_supplicant[1308]: wlan0: Trying to associate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) Nov 12 10:09:42 k15 kernel: [ 12.389114] wlan0: send auth to 64:70:02:89:7c:d7 (try 1/3) Nov 12 10:09:42 k15 kernel: [ 12.391021] wlan0: authenticated Nov 12 10:09:42 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: scanning -> authenticating Nov 12 10:09:42 k15 kernel: [ 12.391332] wlan0: waiting for beacon from 64:70:02:89:7c:d7 Nov 12 10:09:42 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: authenticating -> associating Nov 12 10:09:43 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: associating -> disconnected Nov 12 10:09:43 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: disconnected -> scanning Nov 12 10:09:46 k15 wpa_supplicant[1308]: wlan0: SME: Trying to authenticate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) and after restart WiFi, I could connect: Nov 12 10:11:51 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: inactive -> scanning Nov 12 10:11:55 k15 wpa_supplicant[1308]: wlan0: SME: Trying to authenticate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) Nov 12 10:11:55 k15 kernel: [ 144.445154] wlan0: authenticate with 64:70:02:89:7c:d7 Nov 12 10:11:55 k15 kernel: [ 144.453994] wlan0: send auth to 64:70:02:89:7c:d7 (try 1/3) Nov 12 10:11:55 k15 wpa_supplicant[1308]: wlan0: Trying to associate with 64:70:02:89:7c:d7 (SSID='blab' freq=2427 MHz) Nov 12 10:11:55 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: scanning -> authenticating Nov 12 10:11:55 k15 kernel: [ 144.455860] wlan0: authenticated Nov 12 10:11:55 k15 kernel: [ 144.458681] wlan0: associate with 64:70:02:89:7c:d7 (try 1/3) Nov 12 10:11:55 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: authenticating -> associating Nov 12 10:11:55 k15 kernel: [ 144.462799] wlan0: RX AssocResp from 64:70:02:89:7c:d7 (capab=0x431 status=0 aid=9) Nov 12 10:11:55 k15 kernel: [ 144.486368] wlan0: associated Nov 12 10:11:55 k15 wpa_supplicant[1308]: wlan0: Associated with 64:70:02:89:7c:d7 Nov 12 10:11:55 k15 kernel: [ 144.487435] IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready Nov 12 10:11:55 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: associating -> associated Nov 12 10:11:55 k15 NetworkManager[1004]: <info> (wlan0): supplicant interface state: associated -> 4-way handshake This problem is appearing regulary. My WiFi device control is nl80211. Nov 12 10:09:32 k15 NetworkManager[1004]: <info> (wlan0): using nl80211 for WiFi device control Nov 12 10:09:32 k15 NetworkManager[1004]: <warn> (wlan0): driver supports Access Point (AP) mode Nov 12 10:09:32 k15 NetworkManager[1004]: <info> (wlan0): new 802.11 WiFi device (driver: 'iwlwifi' ifindex: 3) Nov 12 10:09:32 k15 NetworkManager[1004]: <info> (wlan0): exported as /org/freedesktop/NetworkManager/Devices/0 Nov 12 10:09:32 k15 NetworkManager[1004]: <info> (wlan0): now managed Nov 12 10:09:32 k15 NetworkManager[1004]: <info> (wlan0): device state change: unmanaged -> unavailable (reason 'managed') [10 20 2] Nov 12 10:09:32 k15 NetworkManager[1004]: <info> (wlan0): bringing up device.

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• What is the state of the art in OOP?

  - by Ollie Saunders

  I used to do a lot of object-oriented programming and found myself reading up a lot on how to do it well. When C++ was the dominant OOP language there was a very different set of best practices than have emerged since. Some of the newer ideas I know of are BDD, internal DSLs, and the importing of ideas from functional programming. My question is: is there any consensus on the best way to develop object-oriented software today in the more modern languages such as C#, Ruby, and Python? And what are those practices? For instance, I rather like the idea of stateless objects but how many are actually using that in practice? Or, is the state of the art to deemphasize the importance of OOP? This might be the case for some Python programmers but would be difficult for Rubyists.

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• getView only shows Flagged Backgrounds for drawn Views, It does not show Flagged Background when scroll to view more items on list

  - by Leoa

  I am trying to create a listview that receives a flagged list of items to indicate a status to the user. I have been able to create the flag display by using a yellow background (see image at bottom). In Theory, the flagged list can have many flagged items in it. However in my app, only the first three flagged backgrounds are shown. I believe this is because they are initially drawn to the screen. The Flagged background that are not drawn initially to the screen do not show. I'd like to know how to get the remaining flags to show in the list. ListView Recycling: The backgrounds in the listView are being recycled in getView(). This recycling goes from position 0 to position 9. I have flags that need to match at positions 13, 14 and so on. Those positions are not being displayed. listView.getCheckedItemPositions() for multiple selections: This method will not work in my case because the user will not selected the flags. The flags are coming from the server. setNotifyOnChange() and/or public virtual void SetNotifyOnChange (bool notifyOnChange): I'm not adding new data to the list, so I don't see how this method would work for my program. Does this method communicate to getview when it is recycling data? I was unable to find an answer to this in my research. public void registerDataSetObserver: This may be overkill for my problem, but is it possible to have an observer object that keeps track of the all the positions in my items list and in my flag list no matter if the view is recycled and match them on the screen? Code: package com.convention.notification.app; import java.util.Iterator; import java.util.ArrayList; import java.util.List; import android.app.Activity; import android.content.Context; import android.graphics.Color; import android.os.Bundle; import android.text.Html; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.ViewParent; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.TextView; public class NewsRowAdapter extends ArrayAdapter<Item> { private Activity activity; private List<Item> items; private Item objBean; private int row; private List<Integer> disable; View view ; int disableView; public NewsRowAdapter(Activity act, int resource, List<Item> arrayList, List<Integer> disableList) { super(act, resource, arrayList); this.activity = act; this.row = resource; this.items = arrayList; this.disable=disableList; System.out.println("results of delete list a:"+disable.toString()); } public int getCount() { return items.size(); } public Item getItem(int position) { return items.get(position); } public long getItemId(int position) { return position; } @Override public int getItemViewType(int position) { for(int k =0;k < disable.size();k++){ if(position==disable.get(k)){ //System.out.println( "is "+position+" value of disable "+disable.get(k)); disableView=disable.get(k); //AdapterView.getItemAtPosition(position); } } return position; } @Override public View getView(final int position, View convertView, ViewGroup parent) { View view = convertView; ViewHolder holder; if (view == null) { LayoutInflater inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE); view = inflater.inflate(row, null); getItemViewType(position); long id=getItemId(position); if(position==disableView){ view.setBackgroundColor(Color.YELLOW); System.out.println(" background set to yellow at position "+position +" disableView is at "+disableView); }else{ view.setBackgroundColor(Color.WHITE); System.out.println(" background set to white at position "+position +" disableView is at "+disableView); } //ViewHolder is a custom class that gets TextViews by name: tvName, tvCity, tvBDate, tvGender, tvAge; holder = new ViewHolder(); /* setTag Sets the tag associated with this view. A tag can be used to * mark a view in its hierarchy and does not have to be unique * within the hierarchy. Tags can also be used to store data within * a view without resorting to another data structure. */ view.setTag(holder); } else { //the Object stored in this view as a tag holder = (ViewHolder) view.getTag(); } if ((items == null) || ((position + 1) > items.size())) return view; objBean = items.get(position); holder.tv_event_name = (TextView) view.findViewById(R.id.tv_event_name); holder.tv_event_date = (TextView) view.findViewById(R.id.tv_event_date); holder.tv_event_start = (TextView) view.findViewById(R.id.tv_event_start); holder.tv_event_end = (TextView) view.findViewById(R.id.tv_event_end); holder.tv_event_location = (TextView) view.findViewById(R.id.tv_event_location); if (holder.tv_event_name != null && null != objBean.getName() && objBean.getName().trim().length() > 0) { holder.tv_event_name.setText(Html.fromHtml(objBean.getName())); } if (holder.tv_event_date != null && null != objBean.getDate() && objBean.getDate().trim().length() > 0) { holder.tv_event_date.setText(Html.fromHtml(objBean.getDate())); } if (holder.tv_event_start != null && null != objBean.getStartTime() && objBean.getStartTime().trim().length() > 0) { holder.tv_event_start.setText(Html.fromHtml(objBean.getStartTime())); } if (holder.tv_event_end != null && null != objBean.getEndTime() && objBean.getEndTime().trim().length() > 0) { holder.tv_event_end.setText(Html.fromHtml(objBean.getEndTime())); } if (holder.tv_event_location != null && null != objBean.getLocation () && objBean.getLocation ().trim().length() > 0) { holder.tv_event_location.setText(Html.fromHtml(objBean.getLocation ())); } return view; } public class ViewHolder { public TextView tv_event_name, tv_event_date, tv_event_start, tv_event_end, tv_event_location /*tv_event_delete_flag*/; } } Logcat: 06-12 20:54:12.058: I/System.out(493): item disalbed is at postion :0 06-12 20:54:12.058: I/System.out(493): item disalbed is at postion :4 06-12 20:54:12.069: I/System.out(493): item disalbed is at postion :5 06-12 20:54:12.069: I/System.out(493): item disalbed is at postion :13 06-12 20:54:12.069: I/System.out(493): item disalbed is at postion :14 06-12 20:54:12.069: I/System.out(493): item disalbed is at postion :17 06-12 20:54:12.069: I/System.out(493): results of delete list :[0, 4, 5, 13, 14, 17] 06-12 20:54:12.069: I/System.out(493): results of delete list a:[0, 4, 5, 13, 14, 17] 06-12 20:54:12.069: I/System.out(493): set adapaer to list view called; 06-12 20:54:12.128: I/System.out(493): background set to yellow at position 0 disableView is at 0 06-12 20:54:12.628: I/System.out(493): background set to white at position 1 disableView is at 0 06-12 20:54:12.678: I/System.out(493): background set to white at position 2 disableView is at 0 06-12 20:54:12.708: I/System.out(493): background set to white at position 3 disableView is at 0 06-12 20:54:12.738: I/System.out(493): background set to yellow at position 4 disableView is at 4 06-12 20:54:12.778: I/System.out(493): background set to yellow at position 5 disableView is at 5 06-12 20:54:12.808: I/System.out(493): background set to white at position 6 disableView is at 5 06-12 20:54:12.838: I/System.out(493): background set to white at position 7 disableView is at 5 This is a link to my first question a day ago: Change Background on a specific row based on a condition in Custom Adapter I appreciate your help!

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• Why is the ASP.NET Repeater.Items collection empty, when controls are on the screen?

  - by Ryan

  I have an ASP page with the following repeater: <asp:Repeater runat="server" ID="RegionRepeater" DataSourceID="SqlDataSourceRegions" EnableViewState="true"> <ItemTemplate> <tr> <td valign="top"> <b><%#Eval("description")%></b> <asp:HiddenField runat="server" ID="RegionID" Value='<%#Eval("region_id")%>'/> </td> <td> <asp:FileUpload ID="FileUpload" runat="server" Width="368px" /> </td> </tr> </ItemTemplate> </asp:Repeater> (The repeater is inside a Wizard, inside a content pane). The code behind is connected to the protected void Wizard1_NextButtonClick(object sender, WizardNavigationEventArgs e) event. There are two items on the screen (two rows inside the table). However, when the code tries to read those items, the Items collection is empty! foreach(RepeaterItem region in RegionRepeater.Items) { // Never runs - the RegionRepeater.Items.Count = 0 FileUpload fileUpload = (FileUpload) region.FindControl("FileUpload"); String regionID = ((HiddenField)region.FindControl("RegionID")).Value; ... Why is the collection empty, when there are controls drawn on the screen? Thanks a lot for any help; this is starting to drive me nuts. (BTW: I tried adding/removing the EnableViewState="true" tag)

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• How to correctly remove items from Wine Programs menu?

  - by Ivan

  As soon as a Windows application creates a shortcut/directory in Wine Start Menu Programs directory (in particular I do this manually by means of Total Commander and it works), it gets reflected in Ubuntu Wine Programs menu. But when a shortcut/folder is removed (manually, by means of Total Commander again) - Ubuntu Wine Programs menu item persists, and this is an undesirable behaviour. I've once done something causing Wine/Ubuntu to actually refresh the menu state and remove orphan items, but unfortunately I can't remember what. Do you know the way? I am specifically interested in hand-made/removed shortcuts, not installing/uninstalling Windows software.

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• Tab Sweep - State of Java EE, Dynamic JPA, Java EE performance, Garbage Collection, ...

  - by alexismp

  Recent Tips and News on Java EE 6 & GlassFish: • Java EE: The state of the environment (SDTimes) • Extend your Persistence Unit on the fly (EclipseLink blog) • Glassfish 3.1 - AccessLog Format (Ralph) • Java Enterprise Performance - Unburdended Applications (Lucas) • Java Garbage Collection and Heap Analysis (John) • Qu’attendez-vous de JMS 2.0? (Julien) • Dynamically registering WebFilter with Java EE 6 (Markus)

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• Why 11.10 says plymouth errors and "Checking battery state..."?

  - by Aleksi Kinnunen

  I've just installed new Ubuntu 11.10. The installation was successful. But when I start the Ubuntu, the splash screen does not work, and I get error (always some of these) "mountall: Plymouth command failed", "mountall: Connect to Plymouth was lost" or "Checking battery state..." I'm sorry, if the error messages are incorrect because I translated two first of them from Finnish (my system is in Finnish) to English, so they maybe couldn't be just right. I have already asked from our Finnish community, but they couldn't answer. Could anybody here?

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