I have a service that is simply wrapping a component methods.
I create the service programmatically and I need to initialize it with the component (either pass in as a parameter in the constructor, have setter method, or any way). My service is self-hosted in a windows service. I read about IInstanceProvider and ServiceHost aproach, however I think that's probably more used for DI containers and what I need to do should be much more simple.
Any advise would be appreciated. Here's my sample code:
Programmatically creating the service:
_plcServiceHost = new ServiceHost(typeof(PLCService));
foreach (var plc in PLCRepository.GetAllLocal())
{
var baseAddress = plc.LocalEndpointName;
var binding = new NetTcpBinding();
_plcServiceHost.AddServiceEndpoint(typeof(IPLCService), binding, baseAddress);
AddMetadataExchange(_plcServiceHost, baseAddress);
}
_plcServiceHost.Open();
This is how I would like to have my service (2a or 2b).
2a. PLC Service with setter:
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
public class PLCService : IPLCService
{
#region fields
public static volatile object HardwareLock = new object();
private IPLCImpl _plc;
private Semaphore _unsubscribeSem;
private bool _isSubscribed;
#endregion
public void SetPLC(IPLCImpl plc)
{
if (plc == null) throw new ArgumentNullException("plc");
_plc = plc;
_plc.Connect();
}
2b. PLC Service with initialization on constructor:
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
public class PLCService : IPLCService
{
#region fields
public static volatile object HardwareLock = new object();
private readonly IPLCImpl _plc;
private Semaphore _unsubscribeSem;
private bool _isSubscribed;
#endregion
public PLCService(IPLCImpl plc)
{
if (plc == null) throw new ArgumentNullException("plc");
_plc = plc;
_plc.Connect();
}
You can init the implementation from outside of your service, using mentioned DI like Unity, Castle, and so on.
In this way, you can just use it in PLCService constructor.
Related
I am trying to create Singleton CacheManager class that has dependency on IMemoryCache.
public class CacheManager:ICacheManager
{
private readonly IMemoryCache _cache;
public CacheManager(IMemoryCache cache)
{
_cache = cache;
}
public void LoadCache(MyData data)
{
// load cache here at startup from DB
}
}
I also have a Scoped service that retrives data from the database
public class LookupService:ILookupService
{
private readonly MyDatabaseContext _dbContext;
public class LookupService(MyDatabaseContext dbContext)
{
_dbContext = dbContext;
}
public void Dispose()
{
//Dispose DBContext here
}
// some async methods that returns lookup collection
}
Register these services in Startup.cs
public void ConfigureServices(IServiceCollection services)
{
// EF
services.AddDbContext<MyDatabaseContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
// domain services
services.AddScoped<ILookupService, LookupService>();
services.AddMemoryCache();
// singleton
services.AddSingleton<CacheManager>(sp=>
{
using(var scope = sp.CreateScope())
{
using (var service = scope.ServiceProvider.GetService<ILookupService>())
{
how do i create cacheManager instance by injecting IMemoryCache and also register callback function
}
}
});
}
ILookupService is registered as Scoped service becuase it has dependency on DBContext which is also (by default) registered with Scoped lifetime. I do not want to change lifetime of these services.
However I want CacheManager to be registered as Singleton, that means I cannot inject ILookupService as dependency into CacheManager.
So here is my possible solution to create & register singleton instance of CacheManager
services.AddSingleton<CacheManager>(sp=>
{
using(var scope = sp.CreateScope())
{
using (var lookupService = scope.ServiceProvider.GetService<ILookupService>())
{
var cache = scope.ServiceProvider.GetService<IMemoryCache>();
var manger = new CacheManager(cache);
manger.LoadCache(lookupService.GetData());
return manger;
}
}
});
Not sure this is the best way to create CacheManager. How do I implement a callback function to re-populate CacheEntry if it becomes null?
I guess I would simply configure services.AddSingleton<CacheManager>();
(CacheManager having a default constructor)
After configuring all of the DI dependencies and having a serviceprovider, get the Cachemanager singleton and initialize it with LoadCache.
(so let DI create "empty" singleton cachemanager, but initialize immediately somewhere in startup of application)
var cachemanager = scope.ServiceProvider.Get<CacheManager>();
var lookupService = scope.ServiceProvider.Get<ILookupService>();
var cache = scope.ServiceProvider.Get<IMemoryCache>();
cachemanager.Cache = cache;
cachemanager.LoadCache(lookupService.GetData());
Looks like the underlying issue is that ILookupService cannot be resolved until runtime and requests start coming in. You need to create CacheManager before this.
DI COMPOSITION
This should be done when the app starts - as in this class of mine. Note the different lifetimes for different types of object but I just focus on creating the objects rather than interactions.
DI RESOLUTION
.Net uses a container per request pattern where scoped objects are stored against the HttpRequest object. So a singleton basically needs to ask for the current ILookupService, which is done by calling:
container.GetService<ILookupService>
So include the DI container as a constructor argument to your CacheManager class and you will be all set up. This is the service locator pattern and is needed to meet your requirement.
An alternative per request resolution mechanism is via the HttpContext object as in this class, where the following code is used:
IAuthorizer authorizer = (IAuthorizer)this.Context.RequestServices.GetService(typeof(IAuthorizer));
SUMMARY
The important thing is to understand the above design pattern, and you can then apply it to any technology.
register Cache service as singleton, try below code
public class CacheService : ICacheService
{
private ObjectCache _memoryCache;
/// <summary>
/// Initializes a new instance of the <see cref="CacheService"/> class.
/// </summary>
public CacheService()
{
this._memoryCache = System.Runtime.Caching.MemoryCache.Default;
}
}
I have got WCF service running as Windows service and I need to run a method of the WCF Service when Windows Service is starting. Is it possible in any way?
[ServiceContract]
public interface IWebMonitorServiceLibrary
{
[OperationContract]
void TestMethod();
}
[ServiceBehavior(IncludeExceptionDetailInFaults = true)]
public class WebMonitorServiceLibrary : IWebMonitorServiceLibrary
{
#region properties
#endregion
#region events
#endregion
public WebMonitorServiceLibrary()
{
Initialization();
}
private void Initialization()
{
/////////
}
public void TestMethod()
{
//////////
}
}
You don't explain why you want this initialization code to run, but given you almost never want to use a single-instance WCF service, the proper way would be to use dependency injection (see How do I pass values to the constructor on my wcf service?).
Create an object in which you store the things you want to initialize, which you initialize on your Windows Service start:
public class SomeSettingsYouWantToInitialize
{
public string SomeSetting { get; set; }
}
public class WindowsServiceInstance : ServiceBase
{
protected override void OnStart(string[] args)
{
InitializeWcfService();
}
private void InitializeWcfService()
{
var settings = new SomeSettingsYouWantToInitialize
{
SomeSetting = "Foo"
};
_yourDependencyContainer.Register<SomeSettingsYouWantToInitialize>(settings);
}
}
Then (using whatever dependency injection framework you use), inject that into your service's constructor:
public class WebMonitorServiceLibrary
{
public WebMonitorServiceLibrary(SomeSettingsYouWantToInitialize settings)
{
// do stuff with settings
}
}
Generally, no. This is because by default (and following best practice) you will have configured your service to run per-call (or per session), which means there can be multiple instances of your actual service running in your service host.
Therefore, any requirement for you to be able to return an instance of the service from the service host will involve some nasty plumbing code and is not advised.
Specifically, however, there are two approaches you could use to do what you want.
The first involves running your service in InstanceContextMode.Single - this means there will be a single service instance which will handle all requests. If you do this then you can simply create the service instance and then pass it into the servicehost when you start the windows service:
var service = new MyService();
var host = new ServiceHost(service);
You then have access to the service instance and can call the operation directly.
service.MyOperation("something");
The second thing you can do for when you don't want to run a singleton service you can make your service implementation just a wrapper around a static instance of a shared class that actually process the requests. As an example:
public class MyService : IMyService
{
private static IMyService instance = new MySharedServiceClass();
public static IMyService Instance
{
get { return instance ; }
}
public bool MyOperation(string something)
{
return instance.MyOperation(something);
}
}
Then you can call the method on the class like this:
var host = new ServiceHost(typeof(MyService));
var instance = MyService.Instance;
instance.MyOperation("something");
I would still avoid doing this if at all possible. Think to yourself why do you even want this method called on startup? Surely it would be better to have this code directly in the windows service if it's something that needs to be run on startup?
I have created a very simple server and client console app demonstrating the issue I have in that I am trying to bring an instance of a serializable object across to the client but it fails on the server.
What am I missing?? I am NOT concerned right now having it Service orientated using DataContracts - I am simply trying to understand why the code as it stands doesn't bring the EJob accross to the client (it DOES however calls the 'Hello from the server' message)
Many thanks.
EDIT
Even if I decorate the EJob class with a DataContract attribute (like below) it STILL doesn't work - the object I receive on the client has LastName set to null?????
[DataContract]
public class EJob
{
[DataMember]
public string LastName = "Smith";
}
SERVER
namespace testServer
{
[ServiceContract()]
public interface IRemoteClient
{
[OperationContract]
void SayHi(string msg);
[OperationContract]
void ProcessJob(EJob job);
}
[Serializable()]
public class EJob
{
public string LastName = "Smith";
}
class Program
{
static void Main(string[] args)
{
MngrServer.SendJob();
}
}
public class MngrServer
{
public static void SendJob()
{
try
{
// send this off to the correct exe
NetTcpBinding binding = new NetTcpBinding(SecurityMode.None, true);
string address = string.Format("net.tcp://localhost:33888/BatchMananger/client");
EndpointAddress epa = new EndpointAddress(address);
// create the proxy pointing to the correct exe
IRemoteClient clientProxy = ChannelFactory<IRemoteClient>.CreateChannel(binding, epa);
clientProxy.SayHi("Hello from server"); <-- THIS WORKS FINE
EJob job = new EJob { LastName = "Janssen" };
clientProxy.ProcessJob(job); <-- THIS RAISES AN EXCEPTION see below...
}
catch (Exception ex)
{
string msg = ex.Message;
//The formatter threw an exception while trying to deserialize the message: There was an error while
//trying to deserialize parameter http://tempuri.org/:job. The InnerException message was ''EndElement' 'job'
//from namespace 'http://tempuri.org/' is not expected. Expecting element 'LastName'.'.
}
}
}
}
CLIENT
namespace testClient
{
[ServiceContract()]
public interface IRemoteClient
{
[OperationContract]
void SayHi(string msg);
[OperationContract]
void ProcessJob(EJob job);
}
[Serializable()]
public class EJob
{
public string LastName = "Smith";
}
class Program
{
static void Main(string[] args)
{
MngrClient.Prepare();
Console.ReadLine();
}
}
/// <summary>
/// STATIC / INSTANCE
/// </summary>
public class MngrClient : IRemoteClient
{
public void SayHi(string msg)
{
Console.WriteLine(msg);
}
public void ProcessJob(EJob job)
{
Console.WriteLine(job.LastName);
}
public static void Prepare()
{
// allow this class to be used! - so instances are created and info directly passed on to its static members.
ServiceHost sh = new ServiceHost(typeof(MngrClient));
// create the net binding
NetTcpBinding binding = new NetTcpBinding(SecurityMode.None, true);
// define the tcpaddress
string address = string.Format("net.tcp://localhost:33888/BatchMananger/client");
// add a service point so my server can reach me
sh.AddServiceEndpoint(typeof(IRemoteClient), binding, address);
// now open the service for business
sh.Open();
}
}
}
Your EJob datacontract is in a different namespace on the server vs. the client. You need to either declare both classes in the same namespace, or use attributes to set the namespace on the client to match the namespace on the server
(Either the Datacontract attribute has a namespace value that you can pass, or there is a separate namespace attribute that you can use to tell WCF to use an alternate namespace for the contract, can't remember off the top of my head)
EDIT
Just verified -- it's the Namespace property of the DataContractAttribute that you want, so in your client-side declaration:
[DataContract(Namespace="EJobNamespaceAsItIsDeclaredOnTheServer")]
public class EJob ...
Now, it is very common to put all of your DataContracts in a separate assembly (called a contract assembly) that is referenced by both the client and the server. You would want just the contract class definitions in that assembly, nothing else.
You somehow have it all a bit backwards...
given your service contract of IRemoteClient, you should then have an implementation class on the server-side that implements that interface:
public class ServiceImplementation : IRemoteClient
{
public void SayHi(string msg)
{
.....
}
public void ProcessJob(EJob job)
{
.....
}
}
Also: the service methods should be returning something to the caller! Without a return type, you're kinda creating a black-hole of a service - you can call its methods, but nothing gets returned.... Plus: the service implementation class should NOT be hosting itself! Make that a separate class
you should then have a host class on the server side that hosts this service:
public class HostForYourService
{
public HostForYourService()
{
// send this off to the correct exe
NetTcpBinding binding = new NetTcpBinding(SecurityMode.None, true);
string address = string.Format("net.tcp://localhost:33888/BatchMananger/client");
EndpointAddress epa = new EndpointAddress(address);
ServiceHost sh = new ServiceHost(typeof(ServiceImplementation));
// define the tcpaddress
sh.AddServiceEndpoint(typeof(IRemoteClient), binding, address);
// now open the service for business
sh.Open();
}
and then your client should build the client-side proxy for this service and call it
public class YourServiceClient
{
public void CallService()
{
NetTcpBinding binding = new NetTcpBinding(SecurityMode.None, true);
string address = string.Format("net.tcp://servername:33888/BatchMananger/client");
EndpointAddress epa = new EndpointAddress(address);
// create the proxy pointing to the correct exe
IRemoteClient clientProxy = ChannelFactory<IRemoteClient>.CreateChannel(binding, epa);
clientProxy.SayHi("Hello from server"); <-- THIS WORKS FINE
EJob job = new EJob { LastName = "Janssen" };
clientProxy.ProcessJob(job);
}
}
But again: typically, your service methods should be returning something that the client can then operate on - after all, you typically don't want to do a Console.WriteLine on the server - you want to compute something, look up something etc. and return a response to the client which then in turns can e.g. output the result to the console or something....
I have a WCF process hosted in a windows service.
I am wondering if I can safely have multiple WCF processes that do different things hosted in the same windows service.
Do I have to worry about ports?
I am using a mex endpoint
EDIT: SO seems to be trimming my lengthy code/config example so there's a complete explanation here: http://thegrenade.blogspot.com/2009/08/hosting-multiple-wcf-services-under.html
Here's an example that may help get you going:
class Program {
static void Main() {
if (Environment.UserInteractive) {
ServiceManager serviceManager = new ServiceManager();
serviceManager.OpenAll();
Console.ReadKey();
serviceManager.CloseAll();
}
else
ServiceBase.Run(new WindowsService());
}
}
public class WindowsService : ServiceBase
{
public static string WindowsServiceName = "Windows Service Name";
public static string WindowsServiceDescription = "Windows Service Description";
public static string WindowsServiceUsername = #".\username";
public static string WindowsServicePassword = "password";
private readonly ServiceManager serviceManager = new ServiceManager();
private readonly IContainer components = new Container();
protected override void Dispose(bool disposing) {
if (serviceManager != null) serviceManager.CloseAll();
if (disposing && (components != null)) components.Dispose();
base.Dispose(disposing);
}
public WindowsService() {
ServiceName = WindowsServiceName;
CanStop = true;
}
protected override void OnStart(string[] args) {
base.OnStart(args);
serviceManager.OpenAll();
}
protected override void OnStop() {
serviceManager.CloseAll();
base.OnStop();
}
}
public class ServiceManager {
readonly List<ServiceHost> serviceHosts = new List<ServiceHost>();
public void OpenAll() {
OpenHost<Service1>();
OpenHost<Service2>();
...
}
public void CloseAll() {
foreach (ServiceHost serviceHost in serviceHosts)
serviceHost.Close();
}
private void OpenHost<T>() {
Type type = typeof(T);
ServiceHost serviceHost = new ServiceHost(type);
serviceHost.Open();
serviceHosts.Add(serviceHost);
}
}
/// <remarks>
/// Enables application to be installed as a Windows Service by running InstallUtil
/// </remarks>
[RunInstaller(true)]
public class WcfServiceHostInstaller : Installer {
public WcfServiceHostInstaller() {
Installers.Add(new ServiceInstaller
{
StartType = ServiceStartMode.Automatic,
ServiceName = WindowsService.WindowsServiceName,
Description = WindowsService.WindowsServiceDescription
});
Installers.Add(new ServiceProcessInstaller { Account = ServiceAccount.User, Username = WindowsService.WindowsServiceUsername, Password = WindowsService.WindowsServicePassword });
}
}
And some configuration
Here, the binding & behaviour configuration is shared across services but you may need different configurations for different types of services.
I use different ports for different services, but you don't have to.
...
Yes, you can. I am doing this exact thing in my project, hosting three separate WCF services inside my Windows service. Just make sure that each WCF endpoint, i.e., the address/binding/contract tuple, is unique.
Have a look at this Run WCF ServiceHost with multiple contracts its not exactly what you are asking for but maybe of some use.
Using that plus the InstanceContextMode property of the ServiceBehaviour attribute and the ability to configure Service throttling you should be able to get what you want.
As with #Matt, I've done it too with help from this link.
http://www.codeproject.com/KB/WCF/generic_wcf_host.aspx
So I'm hosting WCF service in a WinForms application. I have the following
[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple,
InstanceContextMode = InstanceContextMode.PerCall)]
public class Test : ITest
{
public string TestIt(string input)
{
Thread.Sleep(5000);
return "test";
}
}
I'm using Named Pipes and have two instances of another application that act as clients to the above WCF service (running in a WinForms application). I thought based on the ConcurrencyMode setting of Multiple that when Client1 calls the Test Service, Client2 doesn't have to wait till the first call is complete. However, when Client1 calls TestIt, Client2 blocks until the call from Client1 is complete!?!?! Shouldn't it make a new instance each time based on the above settings?
Also, is the best way to keep a WinForms application that is hosting a WCF service responsive is by running the WCF service on a separate thread?
NOTE: Setting [CallbackBehavior(UseSynchronizationContext = false)] on the Test class does not alleviate the problem. The service still only responds to one request at a time.
Sounds like you want to set this
http://msdn.microsoft.com/en-us/library/system.servicemodel.servicebehaviorattribute.usesynchronizationcontext.aspx
to false. By default, if there is a synchronization context when service.Open() happens, WCF will pick it up and use it. But if you don't want that feature, this flag is how to turn it off.
After digging into this a bit more the only way I was able to get this to work properly was to start the ServiceHost on a separate thread in the WinForms application. If you don't do that setting the ConcurrencyMode and InstanceContextMode attributes does nothing.
I had the same problem.
My class that implemented Callback also contained methods for wcf client, so when I was calling some method from remote service and service was calling Callback method, I was creating a deadlock.
[CallbackBehavior(UseSynchronizationContext = false, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class AppContext : ICustomerOrderCallback
{
//WCF Proxy client
private CustomerOrderClient _client = null;
public AppContext()
{
InstanceContext context = new InstanceContext(this);
_client = new CustomerOrderClient(context);
_client.Subscribe(); //Remote method for subscribing callback
}
public void SendMessage(string message)
{
//Calling Remote method
_client.SendMessage(message);
}
//....code
//callback method
public void OnMessageReceived(string message)
{
//.....code
}
}
So I created a separate class for callback, added attribute CallBehavior to it and everything worked OK.
public class AppContext
{
private CustomerOrderClient _client = null;
private MyCallbackClass _myCallback = null;
public AppContext()
{
_myCallback = new MyCallbackClass();
InstanceContext context = new InstanceContext(_myCallback);
_client = new CustomerOrderClient(context);
_client.Subscribe();
}
public void SendMessage(string message)
{
_client.SendMessage(message);
}
}
[CallbackBehavior(UseSynchronizationContext = false, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class MyCallbackClass : ICustomerOrderCallback
{
public void OnMessageReceived(string message)
{
//.....code
}
}