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  • Windows Azure Mobile Services: New support for iOS apps, Facebook/Twitter/Google identity, Emails, SMS, Blobs, Service Bus and more

    - by ScottGu
    A few weeks ago I blogged about Windows Azure Mobile Services - a new capability in Windows Azure that makes it incredibly easy to connect your client and mobile applications to a scalable cloud backend. Earlier today we delivered a number of great improvements to Windows Azure Mobile Services.  New features include: iOS support – enabling you to connect iPhone and iPad apps to Mobile Services Facebook, Twitter, and Google authentication support with Mobile Services Blob, Table, Queue, and Service Bus support from within your Mobile Service Sending emails from your Mobile Service (in partnership with SendGrid) Sending SMS messages from your Mobile Service (in partnership with Twilio) Ability to deploy mobile services in the West US region All of these improvements are now live in production and available to start using immediately. Below are more details on them: iOS Support This week we delivered initial support for connecting iOS based devices (including iPhones and iPads) to Windows Azure Mobile Services.  Like the rest of our Windows Azure SDK, we are delivering the native iOS libraries to enable this under an open source (Apache 2.0) license on GitHub.  We’re excited to get your feedback on this new library through our forum and GitHub issues list, and we welcome contributions to the SDK. To create a new iOS app or connect an existing iOS app to your Mobile Service, simply select the “iOS” tab within the Quick Start view of a Mobile Service within the Windows Azure Portal – and then follow either the “Create a new iOS app” or “Connect to an existing iOS app” link below it: Clicking either of these links will expand and display step-by-step instructions for how to build an iOS application that connects with your Mobile Service: Read this getting started tutorial to walkthrough how you can build (in less than 5 minutes) a simple iOS “Todo List” app that stores data in Windows Azure.  Then follow the below tutorials to explore how to use the iOS client libraries to store data and authenticate users. Get Started with data in Mobile Services for iOS Get Started with authentication in Mobile Services for iOS Facebook, Twitter, and Google Authentication Support Our initial preview of Mobile Services supported the ability to authenticate users of mobile apps using Microsoft Accounts (formerly called Windows Live ID accounts).  This week we are adding the ability to also authenticate users using Facebook, Twitter, and Google credentials.  These are now supported with both Windows 8 apps as well as iOS apps (and a single app can support multiple forms of identity simultaneously – so you can offer your users a choice of how to login). The below tutorials walkthrough how to register your Mobile Service with an identity provider: How to register your app with Microsoft Account How to register your app with Facebook How to register your app with Twitter How to register your app with Google The tutorials above walkthrough how to obtain a client ID and a secret key from the identity provider. You can then click on the “Identity” tab of your Mobile Service (within the Windows Azure Portal) and save these values to enable server-side authentication with your Mobile Service: You can then write code within your client or mobile app to authenticate your users to the Mobile Service.  For example, below is the code you would write to have them login to the Mobile Service using their Facebook credentials: Windows Store App (using C#): var user = await App.MobileService                     .LoginAsync(MobileServiceAuthenticationProvider.Facebook); iOS app (using Objective C): UINavigationController *controller = [self.todoService.client     loginViewControllerWithProvider:@"facebook"     completion:^(MSUser *user, NSError *error) {        //... }]; Learn more about authenticating Mobile Services using Microsoft Account, Facebook, Twitter, and Google from these tutorials: Get started with authentication in Mobile Services for Windows Store (C#) Get started with authentication in Mobile Services for Windows Store (JavaScript) Get started with authentication in Mobile Services for iOS Using Windows Azure Blob, Tables and ServiceBus with your Mobile Services Mobile Services provide a simple but powerful way to add server logic using server scripts. These scripts are associated with the individual CRUD operations on your mobile service’s tables. Server scripts are great for data validation, custom authorization logic (e.g. does this user participate in this game session), augmenting CRUD operations, sending push notifications, and other similar scenarios.   Server scripts are written in JavaScript and are executed in a secure server-side scripting environment built using Node.js.  You can edit these scripts and save them on the server directly within the Windows Azure Portal: In this week’s release we have added the ability to work with other Windows Azure services from your Mobile Service server scripts.  This is supported using the existing “azure” module within the Windows Azure SDK for Node.js.  For example, the below code could be used in a Mobile Service script to obtain a reference to a Windows Azure Table (after which you could query it or insert data into it):     var azure = require('azure');     var tableService = azure.createTableService("<< account name >>",                                                 "<< access key >>"); Follow the tutorials on the Windows Azure Node.js dev center to learn more about working with Blob, Tables, Queues and Service Bus using the azure module. Sending emails from your Mobile Service In this week’s release we have also added the ability to easily send emails from your Mobile Service, building on our partnership with SendGrid. Whether you want to add a welcome email upon successful user registration, or make your app alert you of certain usage activities, you can do this now by sending email from Mobile Services server scripts. To get started, sign up for SendGrid account at http://sendgrid.com . Windows Azure customers receive a special offer of 25,000 free emails per month from SendGrid. To sign-up for this offer, or get more information, please visit http://www.sendgrid.com/azure.html . One you signed up, you can add the following script to your Mobile Service server scripts to send email via SendGrid service:     var sendgrid = new SendGrid('<< account name >>', '<< password >>');       sendgrid.send({         to: '<< enter email address here >>',         from: '<< enter from address here >>',         subject: 'New to-do item',         text: 'A new to-do was added: ' + item.text     }, function (success, message) {         if (!success) {             console.error(message);         }     }); Follow the Send email from Mobile Services with SendGrid tutorial to learn more. Sending SMS messages from your Mobile Service SMS is a key communication medium for mobile apps - it comes in handy if you want your app to send users a confirmation code during registration, allow your users to invite their friends to install your app or reach out to mobile users without a smartphone. Using Mobile Service server scripts and Twilio’s REST API, you can now easily send SMS messages to your app.  To get started, sign up for Twilio account. Windows Azure customers receive 1000 free text messages when using Twilio and Windows Azure together. Once signed up, you can add the following to your Mobile Service server scripts to send SMS messages:     var httpRequest = require('request');     var account_sid = "<< account SID >>";     var auth_token = "<< auth token >>";       // Create the request body     var body = "From=" + from + "&To=" + to + "&Body=" + message;       // Make the HTTP request to Twilio     httpRequest.post({         url: "https://" + account_sid + ":" + auth_token +              "@api.twilio.com/2010-04-01/Accounts/" + account_sid + "/SMS/Messages.json",         headers: { 'content-type': 'application/x-www-form-urlencoded' },         body: body     }, function (err, resp, body) {         console.log(body);     }); I’m excited to be speaking at the TwilioCon conference this week, and will be showcasing some of the cool scenarios you can now enable with Twilio and Windows Azure Mobile Services. Mobile Services availability in West US region Our initial preview of Windows Azure Mobile Services was only supported in the US East region of Windows Azure.  As with every Windows Azure service, overtime we will extend Mobile Services to all Windows Azure regions. With this week’s preview update we’ve added support so that you can now create your Mobile Service in the West US region as well: Summary The above features are all now live in production and are available to use immediately.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using Mobile Services today. Visit the Windows Azure Mobile Developer Center to learn more about how to build apps with Mobile Services. We’ll have even more new features and enhancements coming later this week – including .NET 4.5 support for Windows Azure Web Sites.  Keep an eye out on my blog for details as new features become available. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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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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  • Building a better mouse-trap &ndash; Improving the creation of XML Message Requests using Reflection, XML &amp; XSLT

    - by paulschapman
    Introduction The way I previously created messages to send to the GovTalk service I used the XMLDocument to create the request. While this worked it left a number of problems; not least that for every message a special function would need to created. This is OK for the short term but the biggest cost in any software project is maintenance and this would be a headache to maintain. So the following is a somewhat better way of achieving the same thing. For the purposes of this article I am going to be using the CompanyNumberSearch request of the GovTalk service – although this technique would work for any service that accepted XML. The C# functions which send and receive the messages remain the same. The magic sauce in this is the XSLT which defines the structure of the request, and the use of objects in conjunction with reflection to provide the content. It is a bit like Sweet Chilli Sauce added to Chicken on a bed of rice. So on to the Sweet Chilli Sauce The Sweet Chilli Sauce The request to search for a company based on it’s number is as follows; <GovTalkMessage xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" > <EnvelopeVersion>1.0</EnvelopeVersion> <Header> <MessageDetails> <Class>NumberSearch</Class> <Qualifier>request</Qualifier> <TransactionID>1</TransactionID> </MessageDetails> <SenderDetails> <IDAuthentication> <SenderID>????????????????????????????????</SenderID> <Authentication> <Method>CHMD5</Method> <Value>????????????????????????????????</Value> </Authentication> </IDAuthentication> </SenderDetails> </Header> <GovTalkDetails> <Keys/> </GovTalkDetails> <Body> <NumberSearchRequest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://xmlgw.companieshouse.gov.uk/v1-0/schema/NumberSearch.xsd"> <PartialCompanyNumber>99999999</PartialCompanyNumber> <DataSet>LIVE</DataSet> <SearchRows>1</SearchRows> </NumberSearchRequest> </Body> </GovTalkMessage> This is the XML that we send to the GovTalk Service and we get back a list of companies that match the criteria passed A message is structured in two parts; The envelope which identifies the person sending the request, with the name of the request, and the body which gives the detail of the company we are looking for. The Chilli What makes it possible is the use of XSLT to define the message – and serialization to convert each request object into XML. To start we need to create an object which will represent the contents of the message we are sending. However there is a common properties in all the messages that we send to Companies House. These properties are as follows SenderId – the id of the person sending the message SenderPassword – the password associated with Id TransactionId – Unique identifier for the message AuthenticationValue – authenticates the request Because these properties are unique to the Companies House message, and because they are shared with all messages they are perfect candidates for a base class. The class is as follows; using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Security.Cryptography; using System.Text; using System.Text.RegularExpressions; using Microsoft.WindowsAzure.ServiceRuntime; namespace CompanyHub.Services { public class GovTalkRequest { public GovTalkRequest() { try { SenderID = RoleEnvironment.GetConfigurationSettingValue("SenderId"); SenderPassword = RoleEnvironment.GetConfigurationSettingValue("SenderPassword"); TransactionId = DateTime.Now.Ticks.ToString(); AuthenticationValue = EncodePassword(String.Format("{0}{1}{2}", SenderID, SenderPassword, TransactionId)); } catch (System.Exception ex) { throw ex; } } /// <summary> /// returns the Sender ID to be used when communicating with the GovTalk Service /// </summary> public String SenderID { get; set; } /// <summary> /// return the password to be used when communicating with the GovTalk Service /// </summary> public String SenderPassword { get; set; } // end SenderPassword /// <summary> /// Transaction Id - uses the Time and Date converted to Ticks /// </summary> public String TransactionId { get; set; } // end TransactionId /// <summary> /// calculate the authentication value that will be used when /// communicating with /// </summary> public String AuthenticationValue { get; set; } // end AuthenticationValue property /// <summary> /// encodes password(s) using MD5 /// </summary> /// <param name="clearPassword"></param> /// <returns></returns> public static String EncodePassword(String clearPassword) { MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider(); byte[] hashedBytes; UTF32Encoding encoder = new UTF32Encoding(); hashedBytes = md5Hasher.ComputeHash(ASCIIEncoding.Default.GetBytes(clearPassword)); String result = Regex.Replace(BitConverter.ToString(hashedBytes), "-", "").ToLower(); return result; } } } There is nothing particularly clever here, except for the EncodePassword method which hashes the value made up of the SenderId, Password and Transaction id. Each message inherits from this object. So for the Company Number Search in addition to the properties above we need a partial number, which dataset to search – for the purposes of the project we only need to search the LIVE set so this can be set in the constructor and the SearchRows. Again all are set as properties. With the SearchRows and DataSet initialized in the constructor. public class CompanyNumberSearchRequest : GovTalkRequest, IDisposable { /// <summary> /// /// </summary> public CompanyNumberSearchRequest() : base() { DataSet = "LIVE"; SearchRows = 1; } /// <summary> /// Company Number to search against /// </summary> public String PartialCompanyNumber { get; set; } /// <summary> /// What DataSet should be searched for the company /// </summary> public String DataSet { get; set; } /// <summary> /// How many rows should be returned /// </summary> public int SearchRows { get; set; } public void Dispose() { DataSet = String.Empty; PartialCompanyNumber = String.Empty; DataSet = "LIVE"; SearchRows = 1; } } As well as inheriting from our base class, I have also inherited from IDisposable – not just because it is just plain good practice to dispose of objects when coding, but it gives also gives us more versatility when using the object. There are four stages in making a request and this is reflected in the four methods we execute in making a call to the Companies House service; Create a request Send a request Check the status If OK then get the results of the request I’ve implemented each of these stages within a static class called Toolbox – which also means I don’t need to create an instance of the class to use it. When making a request there are three stages; Get the template for the message Serialize the object representing the message Transform the serialized object using a predefined XSLT file. Each of my templates I have defined as an embedded resource. When retrieving a resource of this kind we have to include the full namespace to the resource. In making the code re-usable as much as possible I defined the full ‘path’ within the GetRequest method. requestFile = String.Format("CompanyHub.Services.Schemas.{0}", RequestFile); So we now have the full path of the file within the assembly. Now all we need do is retrieve the assembly and get the resource. asm = Assembly.GetExecutingAssembly(); sr = asm.GetManifestResourceStream(requestFile); Once retrieved  So this can be returned to the calling function and we now have a stream of XSLT to define the message. Time now to serialize the request to create the other side of this message. // Serialize object containing Request, Load into XML Document t = Obj.GetType(); ms = new MemoryStream(); serializer = new XmlSerializer(t); xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII); serializer.Serialize(xmlTextWriter, Obj); ms = (MemoryStream)xmlTextWriter.BaseStream; GovTalkRequest = Toolbox.ConvertByteArrayToString(ms.ToArray()); First off we need the type of the object so we make a call to the GetType method of the object containing the Message properties. Next we need a MemoryStream, XmlSerializer and an XMLTextWriter so these can be initialized. The object is serialized by making the call to the Serialize method of the serializer object. The result of that is then converted into a MemoryStream. That MemoryStream is then converted into a string. ConvertByteArrayToString This is a fairly simple function which uses an ASCIIEncoding object found within the System.Text namespace to convert an array of bytes into a string. public static String ConvertByteArrayToString(byte[] bytes) { System.Text.ASCIIEncoding enc = new System.Text.ASCIIEncoding(); return enc.GetString(bytes); } I only put it into a function because I will be using this in various places. The Sauce When adding support for other messages outside of creating a new object to store the properties of the message, the C# components do not need to change. It is in the XSLT file that the versatility of the technique lies. The XSLT file determines the format of the message. For the CompanyNumberSearch the XSLT file is as follows; <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="/"> <GovTalkMessage xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" > <EnvelopeVersion>1.0</EnvelopeVersion> <Header> <MessageDetails> <Class>NumberSearch</Class> <Qualifier>request</Qualifier> <TransactionID> <xsl:value-of select="CompanyNumberSearchRequest/TransactionId"/> </TransactionID> </MessageDetails> <SenderDetails> <IDAuthentication> <SenderID><xsl:value-of select="CompanyNumberSearchRequest/SenderID"/></SenderID> <Authentication> <Method>CHMD5</Method> <Value> <xsl:value-of select="CompanyNumberSearchRequest/AuthenticationValue"/> </Value> </Authentication> </IDAuthentication> </SenderDetails> </Header> <GovTalkDetails> <Keys/> </GovTalkDetails> <Body> <NumberSearchRequest xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="http://xmlgw.companieshouse.gov.uk/v1-0/schema/NumberSearch.xsd"> <PartialCompanyNumber> <xsl:value-of select="CompanyNumberSearchRequest/PartialCompanyNumber"/> </PartialCompanyNumber> <DataSet> <xsl:value-of select="CompanyNumberSearchRequest/DataSet"/> </DataSet> <SearchRows> <xsl:value-of select="CompanyNumberSearchRequest/SearchRows"/> </SearchRows> </NumberSearchRequest> </Body> </GovTalkMessage> </xsl:template> </xsl:stylesheet> The outer two tags define that this is a XSLT stylesheet and the root tag from which the nodes are searched for. The GovTalkMessage is the format of the message that will be sent to Companies House. We first set up the XslCompiledTransform object which will transform the XSLT template and the serialized object into the request to Companies House. xslt = new XslCompiledTransform(); resultStream = new MemoryStream(); writer = new XmlTextWriter(resultStream, Encoding.ASCII); doc = new XmlDocument(); The Serialize method require XmlTextWriter to write the XML (writer) and a stream to place the transferred object into (writer). The XML will be loaded into an XMLDocument object (doc) prior to the transformation. // create XSLT Template xslTemplate = Toolbox.GetRequest(Template); xslTemplate.Seek(0, SeekOrigin.Begin); templateReader = XmlReader.Create(xslTemplate); xslt.Load(templateReader); I have stored all the templates as a series of Embedded Resources and the GetRequestCall takes the name of the template and extracts the relevent XSLT file. /// <summary> /// Gets the framwork XML which makes the request /// </summary> /// <param name="RequestFile"></param> /// <returns></returns> public static Stream GetRequest(String RequestFile) { String requestFile = String.Empty; Stream sr = null; Assembly asm = null; try { requestFile = String.Format("CompanyHub.Services.Schemas.{0}", RequestFile); asm = Assembly.GetExecutingAssembly(); sr = asm.GetManifestResourceStream(requestFile); } catch (Exception) { throw; } finally { asm = null; } return sr; } // end private static stream GetRequest We first take the template name and expand it to include the full namespace to the Embedded Resource I like to keep all my schemas in the same directory and so the namespace reflects this. The rest is the default namespace for the project. Then we get the currently executing assembly (which will contain the resources with the call to GetExecutingAssembly() ) Finally we get a stream which contains the XSLT file. We use this stream and then load an XmlReader with the contents of the template, and that is in turn loaded into the XslCompiledTransform object. We convert the object containing the message properties into Xml by serializing it; calling the Serialize() method of the XmlSerializer object. To set up the object we do the following; t = Obj.GetType(); ms = new MemoryStream(); serializer = new XmlSerializer(t); xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII); We first determine the type of the object being transferred by calling GetType() We create an XmlSerializer object by passing the type of the object being serialized. The serializer writes to a memory stream and that is linked to an XmlTextWriter. Next job is to serialize the object and load it into an XmlDocument. serializer.Serialize(xmlTextWriter, Obj); ms = (MemoryStream)xmlTextWriter.BaseStream; xmlRequest = new XmlTextReader(ms); GovTalkRequest = Toolbox.ConvertByteArrayToString(ms.ToArray()); doc.LoadXml(GovTalkRequest); Time to transform the XML to construct the full request. xslt.Transform(doc, writer); resultStream.Seek(0, SeekOrigin.Begin); request = Toolbox.ConvertByteArrayToString(resultStream.ToArray()); So that creates the full request to be sent  to Companies House. Sending the request So far we have a string with a request for the Companies House service. Now we need to send the request to the Companies House Service. Configuration within an Azure project There are entire blog entries written about configuration within an Azure project – most of this is out of scope for this article but the following is a summary. Configuration is defined in two files within the parent project *.csdef which contains the definition of configuration setting. <?xml version="1.0" encoding="utf-8"?> <ServiceDefinition name="OnlineCompanyHub" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceDefinition"> <WebRole name="CompanyHub.Host"> <InputEndpoints> <InputEndpoint name="HttpIn" protocol="http" port="80" /> </InputEndpoints> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" /> <Setting name="DataConnectionString" /> </ConfigurationSettings> </WebRole> <WebRole name="CompanyHub.Services"> <InputEndpoints> <InputEndpoint name="HttpIn" protocol="http" port="8080" /> </InputEndpoints> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" /> <Setting name="SenderId"/> <Setting name="SenderPassword" /> <Setting name="GovTalkUrl"/> </ConfigurationSettings> </WebRole> <WorkerRole name="CompanyHub.Worker"> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" /> </ConfigurationSettings> </WorkerRole> </ServiceDefinition>   Above is the configuration definition from the project. What we are interested in however is the ConfigurationSettings tag of the CompanyHub.Services WebRole. There are four configuration settings here, but at the moment we are interested in the second to forth settings; SenderId, SenderPassword and GovTalkUrl The value of these settings are defined in the ServiceDefinition.cscfg file; <?xml version="1.0"?> <ServiceConfiguration serviceName="OnlineCompanyHub" xmlns="http://schemas.microsoft.com/ServiceHosting/2008/10/ServiceConfiguration"> <Role name="CompanyHub.Host"> <Instances count="2" /> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="DataConnectionString" value="UseDevelopmentStorage=true" /> </ConfigurationSettings> </Role> <Role name="CompanyHub.Services"> <Instances count="2" /> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" /> <Setting name="SenderId" value="UserID"/> <Setting name="SenderPassword" value="Password"/> <Setting name="GovTalkUrl" value="http://xmlgw.companieshouse.gov.uk/v1-0/xmlgw/Gateway"/> </ConfigurationSettings> </Role> <Role name="CompanyHub.Worker"> <Instances count="2" /> <ConfigurationSettings> <Setting name="DiagnosticsConnectionString" value="UseDevelopmentStorage=true" /> </ConfigurationSettings> </Role> </ServiceConfiguration>   Look for the Role tag that contains our project name (CompanyHub.Services). Having configured the parameters we can now transmit the request. This is done by ‘POST’ing a stream of XML to the Companies House servers. govTalkUrl = RoleEnvironment.GetConfigurationSettingValue("GovTalkUrl"); request = WebRequest.Create(govTalkUrl); request.Method = "POST"; request.ContentType = "text/xml"; writer = new StreamWriter(request.GetRequestStream()); writer.WriteLine(RequestMessage); writer.Close(); We use the WebRequest object to send the object. Set the method of sending to ‘POST’ and the type of data as text/xml. Once set up all we do is write the request to the writer – this sends the request to Companies House. Did the Request Work Part I – Getting the response Having sent a request – we now need the result of that request. response = request.GetResponse(); reader = response.GetResponseStream(); result = Toolbox.ConvertByteArrayToString(Toolbox.ReadFully(reader));   The WebRequest object has a GetResponse() method which allows us to get the response sent back. Like many of these calls the results come in the form of a stream which we convert into a string. Did the Request Work Part II – Translating the Response Much like XSLT and XML were used to create the original request, so it can be used to extract the response and by deserializing the result we create an object that contains the response. Did it work? It would be really great if everything worked all the time. Of course if it did then I don’t suppose people would pay me and others the big bucks so that our programmes do not a) Collapse in a heap (this is an area of memory) b) Blow every fuse in the place in a shower of sparks (this will probably not happen this being real life and not a Hollywood movie, but it was possible to blow the sound system of a BBC Model B with a poorly coded setting) c) Go nuts and trap everyone outside the airlock (this was from a movie, and unless NASA get a manned moon/mars mission set up unlikely to happen) d) Go nuts and take over the world (this was also from a movie, but please note life has a habit of being of exceeding the wildest imaginations of Hollywood writers (note writers – Hollywood executives have no imagination and judging by recent output of that town have turned plagiarism into an art form). e) Freeze in total confusion because the cleaner pulled the plug to the internet router (this has happened) So anyway – we need to check to see if our request actually worked. Within the GovTalk response there is a section that details the status of the message and a description of what went wrong (if anything did). I have defined an XSLT template which will extract these into an XML document. <?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ev="http://www.govtalk.gov.uk/CM/envelope" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <xsl:template match="/"> <GovTalkStatus xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <Status> <xsl:value-of select="ev:GovTalkMessage/ev:Header/ev:MessageDetails/ev:Qualifier"/> </Status> <Text> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Text"/> </Text> <Location> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Location"/> </Location> <Number> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Number"/> </Number> <Type> <xsl:value-of select="ev:GovTalkMessage/ev:GovTalkDetails/ev:GovTalkErrors/ev:Error/ev:Type"/> </Type> </GovTalkStatus> </xsl:template> </xsl:stylesheet>   Only thing different about previous XSL files is the references to two namespaces ev & gt. These are defined in the GovTalk response at the top of the response; xsi:schemaLocation="http://www.govtalk.gov.uk/CM/envelope http://xmlgw.companieshouse.gov.uk/v1-0/schema/Egov_ch-v2-0.xsd" xmlns="http://www.govtalk.gov.uk/CM/envelope" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:gt="http://www.govtalk.gov.uk/schemas/govtalk/core" If we do not put these references into the XSLT template then  the XslCompiledTransform object will not be able to find the relevant tags. Deserialization is a fairly simple activity. encoder = new ASCIIEncoding(); ms = new MemoryStream(encoder.GetBytes(statusXML)); serializer = new XmlSerializer(typeof(GovTalkStatus)); xmlTextWriter = new XmlTextWriter(ms, Encoding.ASCII); messageStatus = (GovTalkStatus)serializer.Deserialize(ms);   We set up a serialization object using the object type containing the error state and pass to it the results of a transformation between the XSLT above and the GovTalk response. Now we have an object containing any error state, and the error message. All we need to do is check the status. If there is an error then we can flag an error. If not then  we extract the results and pass that as an object back to the calling function. We go this by guess what – defining an XSLT template for the result and using that to create an Xml Stream which can be deserialized into a .Net object. In this instance the XSLT to create the result of a Company Number Search is; <?xml version="1.0" encoding="us-ascii"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:ev="http://www.govtalk.gov.uk/CM/envelope" xmlns:sch="http://xmlgw.companieshouse.gov.uk/v1-0/schema" exclude-result-prefixes="ev"> <xsl:template match="/"> <CompanySearchResult xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <CompanyNumber> <xsl:value-of select="ev:GovTalkMessage/ev:Body/sch:NumberSearch/sch:CoSearchItem/sch:CompanyNumber"/> </CompanyNumber> <CompanyName> <xsl:value-of select="ev:GovTalkMessage/ev:Body/sch:NumberSearch/sch:CoSearchItem/sch:CompanyName"/> </CompanyName> </CompanySearchResult> </xsl:template> </xsl:stylesheet> and the object definition is; using System; using System.Collections.Generic; using System.Linq; using System.Web; namespace CompanyHub.Services { public class CompanySearchResult { public CompanySearchResult() { CompanyNumber = String.Empty; CompanyName = String.Empty; } public String CompanyNumber { get; set; } public String CompanyName { get; set; } } } Our entire code to make calls to send a request, and interpret the results are; String request = String.Empty; String response = String.Empty; GovTalkStatus status = null; fault = null; try { using (CompanyNumberSearchRequest requestObj = new CompanyNumberSearchRequest()) { requestObj.PartialCompanyNumber = CompanyNumber; request = Toolbox.CreateRequest(requestObj, "CompanyNumberSearch.xsl"); response = Toolbox.SendGovTalkRequest(request); status = Toolbox.GetMessageStatus(response); if (status.Status.ToLower() == "error") { fault = new HubFault() { Message = status.Text }; } else { Object obj = Toolbox.GetGovTalkResponse(response, "CompanyNumberSearchResult.xsl", typeof(CompanySearchResult)); } } } catch (FaultException<ArgumentException> ex) { fault = new HubFault() { FaultType = ex.Detail.GetType().FullName, Message = ex.Detail.Message }; } catch (System.Exception ex) { fault = new HubFault() { FaultType = ex.GetType().FullName, Message = ex.Message }; } finally { } Wrap up So there we have it – a reusable set of functions to send and interpret XML results from an internet based service. The code is reusable with a little change with any service which uses XML as a transport mechanism – and as for the Companies House GovTalk service all I need to do is create various objects for the result and message sent and the relevent XSLT files. I might need minor changes for other services but something like 70-90% will be exactly the same.

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  • Outlook 2013 keeps freezing, semi-consistently

    - by AviD
    I have an oddity of problem with my Outlook's stability. It seems to be freezing up, not at random intervals, but based on a seemingly strange combination of configurations. I have been trying many different combinations, I've even devolved to "Cargo-cult" debugging, since I have no clue what is causing this... Here is my set up - since I don't know for sure which settings are causing the lockup, I'll probably mention irrelevant things: (relatively) clean install of Windows 8 (on hyper-v, if that matters) Clean install of Outlook 2013, fully updated 3 accounts configured: Hotmail account configured with ActiveSync Gmail account Large-ish account (several GB) connected with IMAP Only a few folders are subscribed in IMAP Outlook is set to only display subscribed folders configured to keep messages permanently Google Apps account, connected with IMAP Small account connected with IMAP All folders IMAP subscribed Outlook is set to only display subscribed folders configured to keep messages permanently Several Send/Receive Groups configured, to try different configurations of enabling/disable/partial the different accounts - with different send times, from 60 minutes down to 5 minutes. The problem is that at certain points Outlook completely freezes up and I have to kill it. This is not consistent - there are some things that cause it immediately almost consistently, there are some times that it just happens by itself after some period of time (sometimes a few moments, sometimes a few hours; sometimes while using it, sometimes after I've been away from it for a few hours). I have searched all over, and there seem to be many with similar (apparently) problem, and found numerous "solutions" (some even more cargocultish than mine), but so far none of them worked. I've removed all the accounts, both all together and one at a time, and re-configured them - eventually it freezes up. I've tried uninstalling Outlook, cleaning it up completely - removing files, app settings, registry keys, etc - then reinstalling - eventually it freezes up. I've only enabled the Hotmail account, disabling (but not removing) the Google accounts - apparently this does not lock up. I've enabled the Hotmail and the Gmail accounts, leaving the Apps one disabled - it seems like it does not lock up. With all accounts enabled, it locks up almost immediately after doing a send/receive. With only the Apps account enabled, it seems to not lock up. With the Hotmail and the Apps accounts enabled (Gmail disabled), it seems like it locks up after a random amount of time. With Hotmail enabled, and Gmail and Apps both enabled but set to receive only custom folder downloading (not all subscribed folders) - sometimes it locks up right after a send/receive, sometimes it goes for hours without locking up, and sometimes it only locks up when I send an email. I've tried switching the ports for the Google accounts (SSL/465 vs TLS/587), though I have no idea if this should affect, but no real difference. In short, I honestly have no idea what is actually causing Outlook to lock up, I might be completely barking up the wrong tree. At this point I don't really know what else to try, I'm flipping switches at random here. I would like to have all 3 accounts enabled, ideally in several groups (e.g. pull down only important folders in a group with short interval, and all other folders in a longer interval) - obviously without freezing up at all. I've tried putting in all the important details, if there is anything else important to add please let me know. Another issue that occurred to me might also be connected - the Google accounts don't always synchronize properly, even after a send/receive or "update folder". At least not consistently... though I haven't been able to find a significant connection between this and that.

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  • Redirect network logs from syslog to another file

    - by w0rldart
    I keep logging way to much info (not needed, for now) in my syslog, and not daily or hourly... but instant. If I want to watch for something in my syslog I just can't because the network log keeps interfering. So, how can I redirect network logs to another file and/or stop logging it? Dec 10 17:01:33 user kernel: [ 8716.000587] MediaState is connected Dec 10 17:01:33 user kernel: [ 8716.000599] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:01:33 user kernel: [ 8716.000601] ==>rt_ioctl_giwfreq 11 Dec 10 17:01:33 user kernel: [ 8716.000612] rt28xx_get_wireless_stats ---> Dec 10 17:01:33 user kernel: [ 8716.000615] <--- rt28xx_get_wireless_stats Dec 10 17:01:39 user kernel: [ 8722.000714] MediaState is connected Dec 10 17:01:39 user kernel: [ 8722.000729] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:01:39 user kernel: [ 8722.000732] ==>rt_ioctl_giwfreq 11 Dec 10 17:01:39 user kernel: [ 8722.000747] rt28xx_get_wireless_stats ---> Dec 10 17:01:39 user kernel: [ 8722.000751] <--- rt28xx_get_wireless_stats Dec 10 17:01:44 user kernel: [ 8726.904025] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:01:45 user kernel: [ 8728.003138] MediaState is connected Dec 10 17:01:45 user kernel: [ 8728.003153] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:01:45 user kernel: [ 8728.003157] ==>rt_ioctl_giwfreq 11 Dec 10 17:01:45 user kernel: [ 8728.003171] rt28xx_get_wireless_stats ---> Dec 10 17:01:45 user kernel: [ 8728.003175] <--- rt28xx_get_wireless_stats Dec 10 17:01:51 user kernel: [ 8734.004066] MediaState is connected Dec 10 17:01:51 user kernel: [ 8734.004079] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:01:51 user kernel: [ 8734.004082] ==>rt_ioctl_giwfreq 11 Dec 10 17:01:51 user kernel: [ 8734.004096] rt28xx_get_wireless_stats ---> Dec 10 17:01:51 user kernel: [ 8734.004099] <--- rt28xx_get_wireless_stats Dec 10 17:01:57 user kernel: [ 8740.004108] MediaState is connected Dec 10 17:01:57 user kernel: [ 8740.004119] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:01:57 user kernel: [ 8740.004121] ==>rt_ioctl_giwfreq 11 Dec 10 17:01:57 user kernel: [ 8740.004132] rt28xx_get_wireless_stats ---> Dec 10 17:01:57 user kernel: [ 8740.004135] <--- rt28xx_get_wireless_stats Dec 10 17:01:57 user kernel: [ 8740.436021] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:03 user kernel: [ 8746.005280] MediaState is connected Dec 10 17:02:03 user kernel: [ 8746.005294] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:02:03 user kernel: [ 8746.005298] ==>rt_ioctl_giwfreq 11 Dec 10 17:02:03 user kernel: [ 8746.005312] rt28xx_get_wireless_stats ---> Dec 10 17:02:03 user kernel: [ 8746.005315] <--- rt28xx_get_wireless_stats Dec 10 17:02:09 user kernel: [ 8752.004790] MediaState is connected Dec 10 17:02:09 user kernel: [ 8752.004804] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:02:09 user kernel: [ 8752.004808] ==>rt_ioctl_giwfreq 11 Dec 10 17:02:09 user kernel: [ 8752.004821] rt28xx_get_wireless_stats ---> Dec 10 17:02:09 user kernel: [ 8752.004825] <--- rt28xx_get_wireless_stats Dec 10 17:02:15 user kernel: [ 8757.984031] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:15 user kernel: [ 8758.004078] MediaState is connected Dec 10 17:02:15 user kernel: [ 8758.004094] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:02:15 user kernel: [ 8758.004097] ==>rt_ioctl_giwfreq 11 Dec 10 17:02:15 user kernel: [ 8758.004112] rt28xx_get_wireless_stats ---> Dec 10 17:02:15 user kernel: [ 8758.004116] <--- rt28xx_get_wireless_stats Dec 10 17:02:16 user kernel: [ 8759.492017] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:19 user kernel: [ 8762.002179] SCANNING, suspend MSDU transmission ... Dec 10 17:02:19 user kernel: [ 8762.004291] MlmeScanReqAction -- Send PSM Data frame for off channel RM, SCAN_IN_PROGRESS=1! Dec 10 17:02:19 user kernel: [ 8762.025055] SYNC - BBP R4 to 20MHz.l Dec 10 17:02:19 user kernel: [ 8762.027249] RT35xx: SwitchChannel#1(RF=8, Pwr0=30, Pwr1=25, 2T), N=0xF1, K=0x02, R=0x02 Dec 10 17:02:19 user kernel: [ 8762.170206] RT35xx: SwitchChannel#2(RF=8, Pwr0=30, Pwr1=25, 2T), N=0xF1, K=0x07, R=0x02 Dec 10 17:02:19 user kernel: [ 8762.318211] RT35xx: SwitchChannel#3(RF=8, Pwr0=30, Pwr1=25, 2T), N=0xF2, K=0x02, R=0x02 Dec 10 17:02:19 user kernel: [ 8762.462269] RT35xx: SwitchChannel#4(RF=8, Pwr0=30, Pwr1=25, 2T), N=0xF2, K=0x07, R=0x02 Dec 10 17:02:19 user kernel: [ 8762.606229] RT35xx: SwitchChannel#5(RF=8, Pwr0=30, Pwr1=25, 2T), N=0xF3, K=0x02, R=0x02 Dec 10 17:02:19 user kernel: [ 8762.750202] RT35xx: SwitchChannel#6(RF=8, Pwr0=30, Pwr1=25, 2T), N=0xF3, K=0x07, R=0x02 Dec 10 17:02:20 user kernel: [ 8762.894217] RT35xx: SwitchChannel#7(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF4, K=0x02, R=0x02 Dec 10 17:02:20 user kernel: [ 8763.038202] RT35xx: SwitchChannel#11(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF6, K=0x02, R=0x02 Dec 10 17:02:20 user kernel: [ 8763.040194] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:20 user kernel: [ 8763.040199] BAR(1) : Tid (0) - 03a3:037e Dec 10 17:02:20 user kernel: [ 8763.040387] SYNC - End of SCAN, restore to channel 11, Total BSS[03] Dec 10 17:02:20 user kernel: [ 8763.040400] ScanNextChannel -- Send PSM Data frame Dec 10 17:02:20 user kernel: [ 8763.040402] bFastRoamingScan ~~~~~~~~~~~~~ Get back to send data ~~~~~~~~~~~~~ Dec 10 17:02:20 user kernel: [ 8763.040405] SCAN done, resume MSDU transmission ... Dec 10 17:02:20 user kernel: [ 8763.047022] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:20 user kernel: [ 8763.047026] BAR(1) : Tid (0) - 03a3:03a5 Dec 10 17:02:21 user kernel: [ 8763.898130] bImprovedScan ............. Resume for bImprovedScan, SCAN_PENDING .............. Dec 10 17:02:21 user kernel: [ 8763.898143] SCANNING, suspend MSDU transmission ... Dec 10 17:02:21 user kernel: [ 8763.900245] MlmeScanReqAction -- Send PSM Data frame for off channel RM, SCAN_IN_PROGRESS=1! Dec 10 17:02:21 user kernel: [ 8763.921144] SYNC - BBP R4 to 20MHz.l Dec 10 17:02:21 user kernel: [ 8763.923339] RT35xx: SwitchChannel#8(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF4, K=0x07, R=0x02 Dec 10 17:02:21 user kernel: [ 8763.996019] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:21 user kernel: [ 8764.066221] RT35xx: SwitchChannel#9(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF5, K=0x02, R=0x02 Dec 10 17:02:21 user kernel: [ 8764.210212] RT35xx: SwitchChannel#10(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF5, K=0x07, R=0x02 Dec 10 17:02:21 user kernel: [ 8764.215536] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.215542] BAR(1) : Tid (0) - 0457:0452 Dec 10 17:02:21 user kernel: [ 8764.244000] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.244004] BAR(1) : Tid (0) - 0459:0456 Dec 10 17:02:21 user kernel: [ 8764.253019] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.253023] BAR(1) : Tid (0) - 045c:0458 Dec 10 17:02:21 user kernel: [ 8764.256677] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.256681] BAR(1) : Tid (0) - 045c:045b Dec 10 17:02:21 user kernel: [ 8764.259785] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.259788] BAR(1) : Tid (0) - 045d:045b Dec 10 17:02:21 user kernel: [ 8764.280467] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.280471] BAR(1) : Tid (0) - 045f:045c Dec 10 17:02:21 user kernel: [ 8764.282189] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:21 user kernel: [ 8764.282192] BAR(1) : Tid (0) - 045f:045e Dec 10 17:02:21 user kernel: [ 8764.354204] RT35xx: SwitchChannel#11(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF6, K=0x02, R=0x02 Dec 10 17:02:21 user kernel: [ 8764.356408] ScanNextChannel():Send PWA NullData frame to notify the associated AP! Dec 10 17:02:21 user kernel: [ 8764.498202] RT35xx: SwitchChannel#12(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF6, K=0x07, R=0x02 Dec 10 17:02:21 user kernel: [ 8764.642210] RT35xx: SwitchChannel#13(RF=8, Pwr0=30, Pwr1=28, 2T), N=0xF7, K=0x02, R=0x02 Dec 10 17:02:22 user kernel: [ 8764.790229] RT35xx: SwitchChannel#14(RF=8, Pwr0=30, Pwr1=28, 2T), N=0xF8, K=0x04, R=0x02 Dec 10 17:02:22 user kernel: [ 8764.934238] RT35xx: SwitchChannel#11(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF6, K=0x02, R=0x02 Dec 10 17:02:22 user kernel: [ 8764.935243] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:22 user kernel: [ 8764.935249] BAR(1) : Tid (0) - 048e:0485 Dec 10 17:02:22 user kernel: [ 8764.936423] SYNC - End of SCAN, restore to channel 11, Total BSS[05] Dec 10 17:02:22 user kernel: [ 8764.936436] ScanNextChannel -- Send PSM Data frame Dec 10 17:02:22 user kernel: [ 8764.936440] SCAN done, resume MSDU transmission ... Dec 10 17:02:22 user kernel: [ 8764.940529] RT35xx: SwitchChannel#11(RF=8, Pwr0=29, Pwr1=26, 2T), N=0xF6, K=0x02, R=0x02 Dec 10 17:02:22 user kernel: [ 8764.942178] CntlEnqueueForRecv(): BAR-Wcid(1), Tid (0) Dec 10 17:02:22 user kernel: [ 8764.942182] BAR(1) : Tid (0) - 0493:048e Dec 10 17:02:22 user kernel: [ 8764.942715] CNTL - All roaming failed, restore to channel 11, Total BSS[05] Dec 10 17:02:22 user kernel: [ 8764.948016] MMCHK - No BEACON. restore R66 to the low bound(56) Dec 10 17:02:22 user kernel: [ 8764.948307] ===>rt_ioctl_giwscan. 5(5) BSS returned, data->length = 1111 Dec 10 17:02:23 user kernel: [ 8766.048073] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:23 user kernel: [ 8766.552034] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:27 user kernel: [ 8770.001180] MediaState is connected Dec 10 17:02:27 user kernel: [ 8770.001197] ==>rt_ioctl_giwmode(mode=2) Dec 10 17:02:27 user kernel: [ 8770.001201] ==>rt_ioctl_giwfreq 11 Dec 10 17:02:27 user kernel: [ 8770.001219] rt28xx_get_wireless_stats ---> Dec 10 17:02:27 user kernel: [ 8770.001223] <--- rt28xx_get_wireless_stats Dec 10 17:02:28 user kernel: [ 8771.564020] QuickDRS: TxTotalCnt <= 15, train back to original rate Dec 10 17:02:29 user kernel: [ 8772.064031] QuickDRS: TxTotalCnt <= 15, train back to original rate

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  • WebSocket and Java EE 7 - Getting Ready for JSR 356 (TOTD #181)

    - by arungupta
    WebSocket is developed as part of HTML 5 specification and provides a bi-directional, full-duplex communication channel over a single TCP socket. It provides dramatic improvement over the traditional approaches of Polling, Long-Polling, and Streaming for two-way communication. There is no latency from establishing new TCP connections for each HTTP message. There is a WebSocket API and the WebSocket Protocol. The Protocol defines "handshake" and "framing". The handshake defines how a normal HTTP connection can be upgraded to a WebSocket connection. The framing defines wire format of the message. The design philosophy is to keep the framing minimum to avoid the overhead. Both text and binary data can be sent using the API. WebSocket may look like a competing technology to Server-Sent Events (SSE), but they are not. Here are the key differences: WebSocket can send and receive data from a client. A typical example of WebSocket is a two-player game or a chat application. Server-Sent Events can only push data data to the client. A typical example of SSE is stock ticker or news feed. With SSE, XMLHttpRequest can be used to send data to the server. For server-only updates, WebSockets has an extra overhead and programming can be unecessarily complex. SSE provides a simple and easy-to-use model that is much better suited. SSEs are sent over traditional HTTP and so no modification is required on the server-side. WebSocket require servers that understand the protocol. SSE have several features that are missing from WebSocket such as automatic reconnection, event IDs, and the ability to send arbitrary events. The client automatically tries to reconnect if the connection is closed. The default wait before trying to reconnect is 3 seconds and can be configured by including "retry: XXXX\n" header where XXXX is the milliseconds to wait before trying to reconnect. Event stream can include a unique event identifier. This allows the server to determine which events need to be fired to each client in case the connection is dropped in between. The data can span multiple lines and can be of any text format as long as EventSource message handler can process it. WebSockets provide true real-time updates, SSE can be configured to provide close to real-time by setting appropriate timeouts. OK, so all excited about WebSocket ? Want to convert your POJOs into WebSockets endpoint ? websocket-sdk and GlassFish 4.0 is here to help! The complete source code shown in this project can be downloaded here. On the server-side, the WebSocket SDK converts a POJO into a WebSocket endpoint using simple annotations. Here is how a WebSocket endpoint will look like: @WebSocket(path="/echo")public class EchoBean { @WebSocketMessage public String echo(String message) { return message + " (from your server)"; }} In this code "@WebSocket" is a class-level annotation that declares a POJO to accept WebSocket messages. The path at which the messages are accepted is specified in this annotation. "@WebSocketMessage" indicates the Java method that is invoked when the endpoint receives a message. This method implementation echoes the received message concatenated with an additional string. The client-side HTML page looks like <div style="text-align: center;"> <form action=""> <input onclick="send_echo()" value="Press me" type="button"> <input id="textID" name="message" value="Hello WebSocket!" type="text"><br> </form></div><div id="output"></div> WebSocket allows a full-duplex communication. So the client, a browser in this case, can send a message to a server, a WebSocket endpoint in this case. And the server can send a message to the client at the same time. This is unlike HTTP which follows a "request" followed by a "response". In this code, the "send_echo" method in the JavaScript is invoked on the button click. There is also a <div> placeholder to display the response from the WebSocket endpoint. The JavaScript looks like: <script language="javascript" type="text/javascript"> var wsUri = "ws://localhost:8080/websockets/echo"; var websocket = new WebSocket(wsUri); websocket.onopen = function(evt) { onOpen(evt) }; websocket.onmessage = function(evt) { onMessage(evt) }; websocket.onerror = function(evt) { onError(evt) }; function init() { output = document.getElementById("output"); } function send_echo() { websocket.send(textID.value); writeToScreen("SENT: " + textID.value); } function onOpen(evt) { writeToScreen("CONNECTED"); } function onMessage(evt) { writeToScreen("RECEIVED: " + evt.data); } function onError(evt) { writeToScreen('<span style="color: red;">ERROR:</span> ' + evt.data); } function writeToScreen(message) { var pre = document.createElement("p"); pre.style.wordWrap = "break-word"; pre.innerHTML = message; output.appendChild(pre); } window.addEventListener("load", init, false);</script> In this code The URI to connect to on the server side is of the format ws://<HOST>:<PORT>/websockets/<PATH> "ws" is a new URI scheme introduced by the WebSocket protocol. <PATH> is the path on the endpoint where the WebSocket messages are accepted. In our case, it is ws://localhost:8080/websockets/echo WEBSOCKET_SDK-1 will ensure that context root is included in the URI as well. WebSocket is created as a global object so that the connection is created only once. This object establishes a connection with the given host, port and the path at which the endpoint is listening. The WebSocket API defines several callbacks that can be registered on specific events. The "onopen", "onmessage", and "onerror" callbacks are registered in this case. The callbacks print a message on the browser indicating which one is called and additionally also prints the data sent/received. On the button click, the WebSocket object is used to transmit text data to the endpoint. Binary data can be sent as one blob or using buffering. The HTTP request headers sent for the WebSocket call are: GET ws://localhost:8080/websockets/echo HTTP/1.1Origin: http://localhost:8080Connection: UpgradeSec-WebSocket-Extensions: x-webkit-deflate-frameHost: localhost:8080Sec-WebSocket-Key: mDbnYkAUi0b5Rnal9/cMvQ==Upgrade: websocketSec-WebSocket-Version: 13 And the response headers received are Connection:UpgradeSec-WebSocket-Accept:q4nmgFl/lEtU2ocyKZ64dtQvx10=Upgrade:websocket(Challenge Response):00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 The headers are shown in Chrome as shown below: The complete source code shown in this project can be downloaded here. The builds from websocket-sdk are integrated in GlassFish 4.0 builds. Would you like to live on the bleeding edge ? Then follow the instructions below to check out the workspace and install the latest SDK: Check out the source code svn checkout https://svn.java.net/svn/websocket-sdk~source-code-repository Build and install the trunk in your local repository as: mvn install Copy "./bundles/websocket-osgi/target/websocket-osgi-0.3-SNAPSHOT.jar" to "glassfish3/glassfish/modules/websocket-osgi.jar" in your GlassFish 4 latest promoted build. Notice, you need to overwrite the JAR file. Anybody interested in building a cool application using WebSocket and get it running on GlassFish ? :-) This work will also feed into JSR 356 - Java API for WebSocket. On a lighter side, there seems to be less agreement on the name. Here are some of the options that are prevalent: WebSocket (W3C API, the URL is www.w3.org/TR/websockets though) Web Socket (HTML5 Demos - html5demos.com/web-socket) Websocket (Jenkins Plugin - wiki.jenkins-ci.org/display/JENKINS/Websocket%2BPlugin) WebSockets (Used by Mozilla - developer.mozilla.org/en/WebSockets, but use WebSocket as well) Web sockets (HTML5 Working Group - www.whatwg.org/specs/web-apps/current-work/multipage/network.html) Web Sockets (Chrome Blog - blog.chromium.org/2009/12/web-sockets-now-available-in-google.html) I prefer "WebSocket" as that seems to be most common usage and used by the W3C API as well. What do you use ?

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  • Internet Protocol Suite: Transition Control Protocol (TCP) vs. User Datagram Protocol (UDP)

    How do we communicate over the Internet?  How is data transferred from one machine to another? These types of act ivies can only be done by using one of two Internet protocols currently. The collection of Internet Protocol consists of the Transition Control Protocol (TCP) and the User Datagram Protocol (UDP).  Both protocols are used to send data between two network end points, however they both have very distinct ways of transporting data from one endpoint to another. If transmission speed and reliability is the primary concern when trying to transfer data between two network endpoints then TCP is the proper choice. When a device attempts to send data to another endpoint using TCP it creates a direct connection between both devices until the transmission has completed. The direct connection between both devices ensures the reliability of the transmission due to the fact that no intermediate devices are needed to transfer the data. Due to the fact that both devices have to continuously poll the connection until transmission has completed increases the resources needed to perform the transmission. An example of this type of direct communication can be seen when a teacher tells a students to do their homework. The teacher is talking directly to the students in order to communicate that the homework needs to be done.  Students can then ask questions about the assignment to ensure that they have received the proper instructions for the assignment. UDP is a less resource intensive approach to sending data between to network endpoints. When a device uses UDP to send data across a network, the data is broken up and repackaged with the destination address. The sending device then releases the data packages to the network, but cannot ensure when or if the receiving device will actually get the data.  The sending device depends on other devices on the network to forward the data packages to the destination devices in order to complete the transmission. As you can tell this type of transmission is less resource intensive because not connection polling is needed,  but should not be used for transmitting data with speed or reliability requirements. This is due to the fact that the sending device can not ensure that the transmission is received.  An example of this type of communication can be seen when a teacher tells a student that they would like to speak with their parents. The teacher is relying on the student to complete the transmission to the parents, and the teacher has no guarantee that the student will actually inform the parents about the request. Both TCP and UPD are invaluable when attempting to send data across a network, but depending on the situation one protocol may be better than the other. Before deciding on which protocol to use an evaluation for transmission speed, reliability, latency, and overhead must be completed in order to define the best protocol for the situation.  

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  • Bulk-Batch Email From Microsoft Access

    If your users collect email addresses in a database, odds are before long, someone's going to get it into their head to send out an email "blast" or batch. There are several approaches, but what you really need is an engine to send individualized emails, one at a time...

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  • Python PyBluez loses Bluetooth connection after a while

    - by Travis G.
    I am using Python to write a simple serial Bluetooth script that sends information about my computer stats periodically. The receiving device is a Sparkfun BlueSmirf Silver. The problem is that, after the script runs for a few minutes, it stops sending packets to the receiver and fails with the error: (11, 'Resource temporarily unavailable') Noticing that this inevitably happens, I added some code to automatically try to reopen the connection. However, then I get: Could not connect: (16, 'Device or resource busy') Am I doing something wrong with the connection? Do I need to occasionally reopen the socket? I'm not sure how to recover from this type of error. I understand that sometimes the port will be busy and a write operation is deferred to avoid blocking other processes, but I wouldn't expect the connection to fail so regularly. Any thoughts? Here is the script: import psutil import serial import string import time import bluetooth sampleTime = 1 numSamples = 5 lastTemp = 0 TEMP_CHAR = 't' USAGE_CHAR = 'u' SENSOR_NAME = 'TC0D' #gauges = serial.Serial() #gauges.port = '/dev/rfcomm0' #gauges.baudrate = 9600 #gauges.parity = 'N' #gauges.writeTimeout = 0 #gauges.open() filename = '/sys/bus/platform/devices/applesmc.768/temp2_input' def parseSensorsOutputLinux(output): return int(round(float(output) / 1000)) def connect(): while(True): try: gaugeSocket = bluetooth.BluetoothSocket(bluetooth.RFCOMM) gaugeSocket.connect(('00:06:66:42:22:96', 1)) break; except bluetooth.btcommon.BluetoothError as error: print "Could not connect: ", error, "; Retrying in 5s..." time.sleep(5) return gaugeSocket; gaugeSocket = connect() while(1): usage = psutil.cpu_percent(interval=sampleTime) sensorFile = open(filename) temp = parseSensorsOutputLinux(sensorFile.read()) try: #gauges.write(USAGE_CHAR) gaugeSocket.send(USAGE_CHAR) #gauges.write(chr(int(usage))) #write the first byte gaugeSocket.send(chr(int(usage))) #print("Wrote usage: " + str(int(usage))) #gauges.write(TEMP_CHAR) gaugeSocket.send(TEMP_CHAR) #gauges.write(chr(temp)) gaugeSocket.send(chr(temp)) #print("Wrote temp: " + str(temp)) except bluetooth.btcommon.BluetoothError as error: print "Caught BluetoothError: ", error time.sleep(5) gaugeSocket = connect() pass gaugeSocket.close() EDIT: I should add that this code connects fine after I power-cycle the receiver and start the script. However, it fails after the first exception until I restart the receiver. P.S. This is related to my recent question, Why is /dev/rfcomm0 giving PySerial problems?, but that was more about PySerial specifically with rfcomm0. Here I am asking about general rfcomm etiquette.

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  • PhysicsMouseJoint problem in andengine + Box2d

    - by Nikhil Lamba
    What we can remove from this code i.e from PhysicsMouseJointExample to remove the functionality of drag and drog of sprite but i need all functionality except this only user move the sprite with some force and velocity of fling but user can't move the ball as like drag and drop like moving a finger on screen and sprite move with finger plz plz help me I am Using Below method for Mouse Joint CODE : public MouseJoint createMouseJoint(final IShape pFace, final float pTouchAreaLocalX, final float pTouchAreaLocalY) { final Body body = (Body) pFace.getUserData(); final MouseJointDef mouseJointDef = new MouseJointDef(); final Vector2 localPoint = Vector2Pool.obtain((pTouchAreaLocalX - pFace.getWidth() * 0.5f) / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT, (pTouchAreaLocalY - pFace.getHeight() * 0.5f) / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT); this.groundBody.setTransform(localPoint, 0); mouseJointDef.bodyA = this.groundBody; mouseJointDef.bodyB = body; mouseJointDef.dampingRatio = 0.95f; mouseJointDef.frequencyHz = 30; mouseJointDef.maxForce = (200.0f * body.getMass()); mouseJointDef.collideConnected = true; mouseJointDef.target.set(body.getWorldPoint(localPoint)); Vector2Pool.recycle(localPoint); return (MouseJoint)mPhysicsWorld.createJoint(mouseJointDef); }

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  • Sudden increase in spam report from Yahoo

    - by lulalala
    Recently we experienced a sudden increase in spam reports, and all of them come from Yahoo email addresses. We see lots of registration confirmation email got marked as spam. We also saw people marking mails as spam and then opened it and clicked on the confirmation link. We send around 150 registration emails a day, and currently sees 2 spam reports from these per day. Previously spam reports once come once a month. We use Sendgrid to send emails.

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  • Inserting data to database from Android

    - by Angel
    I have to build an application where the requirement is that my clients will send data from their Android device and I have to save that data to a database. I have done the part of coding that inserts data from Android emulator to my XAMPP database on localhost, now I have to implement the real thing. How can I connect the devices where my application will be installed to the XAMPP database I have created so that the data they send can be inserted into it?

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  • Designing Mobile SMS text advertising system

    - by Ramraj Edagutti
    Currently, I am working on a product where we have an SMS text advertising system, and using this, we setup advertising campaigns for clients, and later these campaigns are sent to the end users. This is very similar to Google Adwords, but targeted to Mobile users via SMS. Just to give an overview of the system Each Campaign is mapped to an advertiser Campaign has start date and end date Campaign has a filter condition(s) or query to select the target user base from our database (to whom we send Campaigns) Target user base can be fixed, for e.g send campaign to 10000 users Target user base can also be dynamic based on query condition, for e.g send campaign to users who are active and from a particular state, district, town etc. (this way user base will be keep changing on daily basis) Campaign can have multiple campaign messages Each campaign message has start date and end date Each campaign message can have multiple message texts for different locales, for e.g English,Hindi,Telugu etc After creating an advertisement campaign, we run daily night job to provision the target user base for that a particular campaign in a separate table, and another daily job runs on morning times and checks provisioned table for campaigns and targeted users and sends the campaign to users via SMS. Problem is, current UI for creating advertising campaigns is designed in a very technical manner, I mean, normal user or business owner or clients can not use the UI to create a campaign. Below are reasons why the UI is very technical in nature Filter condition(s) or query input filed, takes user ids or mobile numbers or SQL queries. Most of times or almost every time, we use big SQL queries So we end up storing SQL queries in a database for a campaign, later we use this SQL query to fetch targeted user base. For scheduling these campaigns, we have input filed on UI which takes quartz cron expression(s) ( for e.g. send campaign on "0 0 9 1-10 MAR 2012" ), again very technical in nature Normal user or business owner, can not use the UI for creating campaigns for reasons mentioned above, Currently, we ourself (developers) helping clients to setup/create campaigns. we are trying to re-design the UI to make it more user friendly so that any user can go to UI and create an advertisement campaign by himself. I am thinking of re-designing the current UI similar to Google Adwords interface, especially for selecting target users based on user geography like country, state, city etc. I also need to select users based user subscription(s), which might make system even more complex. And also, for campaign scheduling, I am thinking of using weekdays with hours. For example, I will shows Monday to Sunday on UI, and user can select the from hours, to hours etc. Any better ideas or suggestion on how to design UI in very user friendly manner and what design should be followed on server side code (we write backend code on java/jpa/spring/quartz)? And I am looking for ideas or design patterns on how to build SQL queries (using JPA/Hinernate) programmatically on server side, based on varies conditions like based on country, state, town, village, and user subscriptions.

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  • Payment Gateway options other than Paypal, for sending out mass payments

    - by Rishav Rastogi
    We were using Paypal Payment pro earlier for the same thing, but for some reason Paypal has been given some new guideline which kinda hinder with the way we need to send out payments at the moment. We receive payments from clients and then send out payments back to vendors on a weekly basis ( deducting our cut ). Can you let me know what options are available to for such transactions other than paypal ? which is the best in terms cost of setup etc. Thanks

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  • Box2D networking

    - by spacevillain
    I am trying to make a simple sync between two box2d rooms, where you can drag boxes using the mouse. So every time player clicks (and holds the mousedown) a box, I try send joint parameters to server, and server sends them to other clients. When mouseup occurs, I send command to delete joint. The problem is that sync breaks too often. Is my way radically wrong, or it just needs some tweaks? http://www.youtube.com/watch?v=eTN2Gwj6_Lc Source code https://github.com/agentcooper/Box2d-networking

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  • checking for collision detection

    - by bill
    I am trying to create a game where you have a player and you can move right,left, and jump. kind of like mario but its not a side scroller. also i want to use 2d array to make a tile map. my big problem is that i dont understand how to check for collision. i spend about 2 week thinking about this and i came up with 2 solution but they both have problems. let say my map is: 0 = sky 1 = player 2 = ground 00000 10002 22022 Solution 1: move the '1'(player) and update the map less say player wants to move right, then x+=grid[x+1][y] this make the collision easy bc you can just check if if(grid[x][y+1] == 2){ //player is standing on top of ground } problem with this when u hit right key player will move (x*Titlewidth) to right. and as you can see the animation wont look smooth. Solution 2: move player and dont update map player_x += 2 this will make the animation more smoother bc i am just moving 2 pixels. problem1: i cant update map bc if player some times will be middle of int(2d array). but thats ok sinces its not a side scroller so updating the map is not a big deal. problem2: only way to check for collision is to use java intersection method. but then player have to be atleast 1 or 2 pixel in ground in order to check for collision. and as you can see that wont look good too. plz note this is my first collision game in java. so plz try to explain alot otherwise i wont understand it.

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  • How can I find out if my domain has been added to email blacklists?

    - by Rob Sobers
    We do a lot of mass emailing of our contacts to promote events, send out newsletters, etc. Some people read and react, some people unsubscribe, but I fear that some might actually mark the email as spam. Is there any way to figure out whether my domain has been added to email blacklists or spam registries? Also, if I use a service like MailChimp to send the emails, how would this work? If one unscrupulous customer was using MailChimp for evil, wouldn't it affect all of their customers?

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  • Component doesn't register in COM+ (4 replies)

    Hi I did a simple COM and when trying to register it gives the following error &quot;One or more files do not contain components or type libraries. These files cannot be installed&quot; I have tried debug/release both versions, still the same. Before adding I have compiled teh component with strong naming as well. The option in the compile option dialog which says &quot;Register for COM interop&quot; have been enable...

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  • Component doesn't register in COM+ (4 replies)

    Hi I did a simple COM and when trying to register it gives the following error &quot;One or more files do not contain components or type libraries. These files cannot be installed&quot; I have tried debug/release both versions, still the same. Before adding I have compiled teh component with strong naming as well. The option in the compile option dialog which says &quot;Register for COM interop&quot; have been enable...

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  • Printer image correction

    - by Matthew Shinal
    Here is my problem: my printer and scanner (HP psc2410xi) prints darker than the photos taken and teh scanner has a background fuzz. I want to create and install files to have the printer lighten the photos it prints (yellow becomes dark yellow, etc) and delete the "fuzz" from the scanner image (you can see it on a blank scan and yes I did clean the scanner). I'm thinking there is a way to take a printed image, scan that in, and subtract the two images from each other to get the correction factor.

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  • What would another Ubuntu user's default font be?

    - by Gonzoza
    If I send an email from, say, Thunderbird, and have "Helvetica/Arial" set as my default outgoing font, then my assumption is that most of the world will read that email in Helvetica (Apple) or Arial (Windows). But what if I send that email to another Ubuntu user who does not have the MS core fonts installed? What will the email's font default to? Would Ubuntu override it with something like sans-serif, perhaps?

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  • Should I set NOINDEX header for my JS, CSS and image files?

    - by Yoga
    Are there any harms if my site send NOINDEX headers for all my static assets? For image files, I refer to those valueless, e.g. background images, button images, etc. Update: more background information I have this concern is since recent Google said they also execute JS and they might fetch content via Ajax. So, for example, if I send noindex for my jQuery script, so Google would not be able to use them to load Ajax, I suppose it is not good for my site's SEO, right?

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  • Why You Should Use SEO

    Search engine optimization (SEO) is a term for optimizing your website so that search engines will be able to find you faster, and also give you a higher ranking. A higher ranking will mean that they will send you more free traffic. And believe it or not, the traffic which the search engines send you, is by far the best traffic which you could hope for.

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