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  • objective-c : @synchronized how it works ?

    - by g.revolution
    Hi, i have two methods -(void) a { @synchronized(self) { // critical section 1 } } -(void) b { @synchronized(self) { // critical section 2 } } now my question is if a thread is in critical section 1. will the critical section 2 be locked for other threads or other threads can access critical section 2.

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  • Subclassing and adding data members

    - by Marius
    I have an hierarchy of classes that looks like the following: class Critical { public: Critical(int a, int b) : m_a(a), m_b(b) { } virtual ~Critical() { } int GetA() { return m_a; } int GetB() { return m_b; } void SetA(int a) { m_a = a; } void SetB(int b) { m_b = b; } protected: int m_a; int m_b; }; class CriticalFlavor : public Critical { public: CriticalFlavor(int a, int b, int flavor) : Critical(a, b), m_flavor(flavor) { } virtual ~CriticalFlavor() { } int GetFlavor() { return m_flavor; } void SetFlavor(int flavor) { m_flavor = flavor; } protected: int m_flavor; }; class CriticalTwist : public Critical { public: CriticalTwist(int a, int b, int twist) : Critical(a, b), m_twist(twist) { } virtual ~CriticalTwist() { } int GetTwist() { return m_twist; } void SetTwist(int twist) { m_twist = twist; } protected: int m_twist; }; The above does not seem right to me in terms of the design and what bothers me the most is the fact that the addition of member variables seems to drive the interface of these classes (the real code that does the above is a little more complex but still embracing the same pattern). That will proliferate when in need for another "Critical" class that just adds some other property. Does this feel right to you? How could I refactor such code? An idea would be to have just a set of interfaces and use composition when it comes to the base object like the following: class Critical { public: virtual int GetA() = 0; virtual int GetB() = 0; virtual void SetA(int a) = 0; virtual void SetB(int b) = 0; }; class CriticalImpl { public: CriticalImpl(int a, int b) : m_a(a), m_b(b) { } ~CriticalImpl() { } int GetA() { return m_a; } int GetB() { return m_b; } void SetA(int a) { m_a = a; } void SetB(int b) { m_b = b; } private: int m_a; int m_b; }; class CriticalFlavor { public: virtual int GetFlavor() = 0; virtual void SetFlavor(int flavor) = 0; }; class CriticalFlavorImpl : public Critical, public CriticalFlavor { public: CriticalFlavorImpl(int a, int b, int flavor) : m_flavor(flavor), m_critical(new CriticalImpl(a, b)) { } ~CriticalFlavorImpl() { delete m_critical; } int GetFlavor() { return m_flavor; } void SetFlavor(int flavor) { m_flavor = flavor; } int GetA() { return m_critical-GetA(); } int GetB() { return m_critical-GetB(); } void SetA(int a) { m_critical-SetA(a); } void SetB(int b) { m_critical-SetB(b); } private: int m_flavor; CriticalImpl* m_critical; };

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  • How to configure a URL with 3 levels in ASP.NET MVC?

    - by MCardinale
    Using ASP.NET MVC, I need to configure my URLs like this: www.foo.com/company : render View Company www.foo.com/company/about : render View Company www.foo.com/company/about/mission : render View Mission If "company" is my controller and "about" is my action, what should be "mission"? For every "folder" (company, about and mission) I have to render a different View. Anyone knows how can I do that? Thanks!

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  • ASP.NET Web API Exception Handling

    - by Fredrik N
    When I talk about exceptions in my product team I often talk about two kind of exceptions, business and critical exceptions. Business exceptions are exceptions thrown based on “business rules”, for example if you aren’t allowed to do a purchase. Business exceptions in most case aren’t important to log into a log file, they can directly be shown to the user. An example of a business exception could be "DeniedToPurchaseException”, or some validation exceptions such as “FirstNameIsMissingException” etc. Critical Exceptions are all other kind of exceptions such as the SQL server is down etc. Those kind of exception message need to be logged and should not reach the user, because they can contain information that can be harmful if it reach out to wrong kind of users. I often distinguish business exceptions from critical exceptions by creating a base class called BusinessException, then in my error handling code I catch on the type BusinessException and all other exceptions will be handled as critical exceptions. This blog post will be about different ways to handle exceptions and how Business and Critical Exceptions could be handled. Web API and Exceptions the basics When an exception is thrown in a ApiController a response message will be returned with a status code set to 500 and a response formatted by the formatters based on the “Accept” or “Content-Type” HTTP header, for example JSON or XML. Here is an example:   public IEnumerable<string> Get() { throw new ApplicationException("Error!!!!!"); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response message will be: HTTP/1.1 500 Internal Server Error Content-Length: 860 Content-Type: application/json; charset=utf-8 { "ExceptionType":"System.ApplicationException","Message":"Error!!!!!","StackTrace":" at ..."} .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The stack trace will be returned to the client, this is because of making it easier to debug. Be careful so you don’t leak out some sensitive information to the client. So as long as you are developing your API, this is not harmful. In a production environment it can be better to log exceptions and return a user friendly exception instead of the original exception. There is a specific exception shipped with ASP.NET Web API that will not use the formatters based on the “Accept” or “Content-Type” HTTP header, it is the exception is the HttpResponseException class. Here is an example where the HttpReponseExcetpion is used: // GET api/values [ExceptionHandling] public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The response will not contain any content, only header information and the status code based on the HttpStatusCode passed as an argument to the HttpResponseMessage. Because the HttpResponsException takes a HttpResponseMessage as an argument, we can give the response a content: public IEnumerable<string> Get() { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("My Error Message"), ReasonPhrase = "Critical Exception" }); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   The code above will have the following response:   HTTP/1.1 500 Critical Exception Content-Length: 5 Content-Type: text/plain; charset=utf-8 My Error Message .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The Content property of the HttpResponseMessage doesn’t need to be just plain text, it can also be other formats, for example JSON, XML etc. By using the HttpResponseException we can for example catch an exception and throw a user friendly exception instead: public IEnumerable<string> Get() { try { DoSomething(); return new string[] { "value1", "value2" }; } catch (Exception e) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Adding a try catch to every ApiController methods will only end in duplication of code, by using a custom ExceptionFilterAttribute or our own custom ApiController base class we can reduce code duplicationof code and also have a more general exception handler for our ApiControllers . By creating a custom ApiController’s and override the ExecuteAsync method, we can add a try catch around the base.ExecuteAsync method, but I prefer to skip the creation of a own custom ApiController, better to use a solution that require few files to be modified. The ExceptionFilterAttribute has a OnException method that we can override and add our exception handling. Here is an example: using System; using System.Diagnostics; using System.Net; using System.Net.Http; using System.Web.Http; using System.Web.Http.Filters; public class ExceptionHandlingAttribute : ExceptionFilterAttribute { public override void OnException(HttpActionExecutedContext context) { if (context.Exception is BusinessException) { throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(context.Exception.Message), ReasonPhrase = "Exception" }); } //Log Critical errors Debug.WriteLine(context.Exception); throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent("An error occurred, please try again or contact the administrator."), ReasonPhrase = "Critical Exception" }); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   Note: Something to have in mind is that the ExceptionFilterAttribute will be ignored if the ApiController action method throws a HttpResponseException. The code above will always make sure a HttpResponseExceptions will be returned, it will also make sure the critical exceptions will show a more user friendly message. The OnException method can also be used to log exceptions. By using a ExceptionFilterAttribute the Get() method in the previous example can now look like this: public IEnumerable<string> Get() { DoSomething(); return new string[] { "value1", "value2" }; } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To use the an ExceptionFilterAttribute, we can for example add the ExceptionFilterAttribute to our ApiControllers methods or to the ApiController class definition, or register it globally for all ApiControllers. You can read more about is here. Note: If something goes wrong in the ExceptionFilterAttribute and an exception is thrown that is not of type HttpResponseException, a formatted exception will be thrown with stack trace etc to the client. How about using a custom IHttpActionInvoker? We can create our own IHTTPActionInvoker and add Exception handling to the invoker. The IHttpActionInvoker will be used to invoke the ApiController’s ExecuteAsync method. Here is an example where the default IHttpActionInvoker, ApiControllerActionInvoker, is used to add exception handling: public class MyApiControllerActionInvoker : ApiControllerActionInvoker { public override Task<HttpResponseMessage> InvokeActionAsync(HttpActionContext actionContext, System.Threading.CancellationToken cancellationToken) { var result = base.InvokeActionAsync(actionContext, cancellationToken); if (result.Exception != null && result.Exception.GetBaseException() != null) { var baseException = result.Exception.GetBaseException(); if (baseException is BusinessException) { return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Error" }); } else { //Log critical error Debug.WriteLine(baseException); return Task.Run<HttpResponseMessage>(() => new HttpResponseMessage(HttpStatusCode.InternalServerError) { Content = new StringContent(baseException.Message), ReasonPhrase = "Critical Error" }); } } return result; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } You can register the IHttpActionInvoker with your own IoC to resolve the MyApiContollerActionInvoker, or add it in the Global.asax: GlobalConfiguration.Configuration.Services.Remove(typeof(IHttpActionInvoker), GlobalConfiguration.Configuration.Services.GetActionInvoker()); GlobalConfiguration.Configuration.Services.Add(typeof(IHttpActionInvoker), new MyApiControllerActionInvoker()); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   How about using a Message Handler for Exception Handling? By creating a custom Message Handler, we can handle error after the ApiController and the ExceptionFilterAttribute is invoked and in that way create a global exception handler, BUT, the only thing we can take a look at is the HttpResponseMessage, we can’t add a try catch around the Message Handler’s SendAsync method. The last Message Handler that will be used in the Wep API pipe-line is the HttpControllerDispatcher and this Message Handler is added to the HttpServer in an early stage. The HttpControllerDispatcher will use the IHttpActionInvoker to invoke the ApiController method. The HttpControllerDipatcher has a try catch that will turn ALL exceptions into a HttpResponseMessage, so that is the reason why a try catch around the SendAsync in a custom Message Handler want help us. If we create our own Host for the Wep API we could create our own custom HttpControllerDispatcher and add or exception handler to that class, but that would be little tricky but is possible. We can in a Message Handler take a look at the HttpResponseMessage’s IsSuccessStatusCode property to see if the request has failed and if we throw the HttpResponseException in our ApiControllers, we could use the HttpResponseException and give it a Reason Phrase and use that to identify business exceptions or critical exceptions. I wouldn’t add an exception handler into a Message Handler, instead I should use the ExceptionFilterAttribute and register it globally for all ApiControllers. BUT, now to another interesting issue. What will happen if we have a Message Handler that throws an exception?  Those exceptions will not be catch and handled by the ExceptionFilterAttribute. I found a  bug in my previews blog post about “Log message Request and Response in ASP.NET WebAPI” in the MessageHandler I use to log incoming and outgoing messages. Here is the code from my blog before I fixed the bug:   public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); var responseMessage = await response.Content.ReadAsByteArrayAsync(); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If a ApiController throws a HttpResponseException, the Content property of the HttpResponseMessage from the SendAsync will be NULL. So a null reference exception is thrown within the MessageHandler. The yellow screen of death will be returned to the client, and the content is HTML and the Http status code is 500. The bug in the MessageHandler was solved by adding a check against the HttpResponseMessage’s IsSuccessStatusCode property: public abstract class MessageHandler : DelegatingHandler { protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var corrId = string.Format("{0}{1}", DateTime.Now.Ticks, Thread.CurrentThread.ManagedThreadId); var requestInfo = string.Format("{0} {1}", request.Method, request.RequestUri); var requestMessage = await request.Content.ReadAsByteArrayAsync(); await IncommingMessageAsync(corrId, requestInfo, requestMessage); var response = await base.SendAsync(request, cancellationToken); byte[] responseMessage; if (response.IsSuccessStatusCode) responseMessage = await response.Content.ReadAsByteArrayAsync(); else responseMessage = Encoding.UTF8.GetBytes(response.ReasonPhrase); await OutgoingMessageAsync(corrId, requestInfo, responseMessage); return response; } protected abstract Task IncommingMessageAsync(string correlationId, string requestInfo, byte[] message); protected abstract Task OutgoingMessageAsync(string correlationId, string requestInfo, byte[] message); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we don’t handle the exceptions that can occur in a custom Message Handler, we can have a hard time to find the problem causing the exception. The savior in this case is the Global.asax’s Application_Error: protected void Application_Error() { var exception = Server.GetLastError(); Debug.WriteLine(exception); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I would recommend you to add the Application_Error to the Global.asax and log all exceptions to make sure all kind of exception is handled. Summary There are different ways we could add Exception Handling to the Wep API, we can use a custom ApiController, ExceptionFilterAttribute, IHttpActionInvoker or Message Handler. The ExceptionFilterAttribute would be a good place to add a global exception handling, require very few modification, just register it globally for all ApiControllers, even the IHttpActionInvoker can be used to minimize the modifications of files. Adding the Application_Error to the global.asax is a good way to catch all unhandled exception that can occur, for example exception thrown in a Message Handler.   If you want to know when I have posted a blog post, you can follow me on twitter @fredrikn

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  • .NET Security Part 3

    - by Simon Cooper
    You write a security-related application that allows addins to be used. These addins (as dlls) can be downloaded from anywhere, and, if allowed to run full-trust, could open a security hole in your application. So you want to restrict what the addin dlls can do, using a sandboxed appdomain, as explained in my previous posts. But there needs to be an interaction between the code running in the sandbox and the code that created the sandbox, so the sandboxed code can control or react to things that happen in the controlling application. Sandboxed code needs to be able to call code outside the sandbox. Now, there are various methods of allowing cross-appdomain calls, the two main ones being .NET Remoting with MarshalByRefObject, and WCF named pipes. I’m not going to cover the details of setting up such mechanisms here, or which you should choose for your specific situation; there are plenty of blogs and tutorials covering such issues elsewhere. What I’m going to concentrate on here is the more general problem of running fully-trusted code within a sandbox, which is required in most methods of app-domain communication and control. Defining assemblies as fully-trusted In my last post, I mentioned that when you create a sandboxed appdomain, you can pass in a list of assembly strongnames that run as full-trust within the appdomain: // get the Assembly object for the assembly Assembly assemblyWithApi = ... // get the StrongName from the assembly's collection of evidence StrongName apiStrongName = assemblyWithApi.Evidence.GetHostEvidence<StrongName>(); // create the sandbox AppDomain sandbox = AppDomain.CreateDomain( "Sandbox", null, appDomainSetup, restrictedPerms, apiStrongName); Any assembly that is loaded into the sandbox with a strong name the same as one in the list of full-trust strong names is unconditionally given full-trust permissions within the sandbox, irregardless of permissions and sandbox setup. This is very powerful! You should only use this for assemblies that you trust as much as the code creating the sandbox. So now you have a class that you want the sandboxed code to call: // within assemblyWithApi public class MyApi { public static void MethodToDoThings() { ... } } // within the sandboxed dll public class UntrustedSandboxedClass { public void DodgyMethod() { ... MyApi.MethodToDoThings(); ... } } However, if you try to do this, you get quite an ugly exception: MethodAccessException: Attempt by security transparent method ‘UntrustedSandboxedClass.DodgyMethod()’ to access security critical method ‘MyApi.MethodToDoThings()’ failed. Security transparency, which I covered in my first post in the series, has entered the picture. Partially-trusted code runs at the Transparent security level, fully-trusted code runs at the Critical security level, and Transparent code cannot under any circumstances call Critical code. Security transparency and AllowPartiallyTrustedCallersAttribute So the solution is easy, right? Make MethodToDoThings SafeCritical, then the transparent code running in the sandbox can call the api: [SecuritySafeCritical] public static void MethodToDoThings() { ... } However, this doesn’t solve the problem. When you try again, exactly the same exception is thrown; MethodToDoThings is still running as Critical code. What’s going on? By default, a fully-trusted assembly always runs Critical code, irregardless of any security attributes on its types and methods. This is because it may not have been designed in a secure way when called from transparent code – as we’ll see in the next post, it is easy to open a security hole despite all the security protections .NET 4 offers. When exposing an assembly to be called from partially-trusted code, the entire assembly needs a security audit to decide what should be transparent, safe critical, or critical, and close any potential security holes. This is where AllowPartiallyTrustedCallersAttribute (APTCA) comes in. Without this attribute, fully-trusted assemblies run Critical code, and partially-trusted assemblies run Transparent code. When this attribute is applied to an assembly, it confirms that the assembly has had a full security audit, and it is safe to be called from untrusted code. All code in that assembly runs as Transparent, but SecurityCriticalAttribute and SecuritySafeCriticalAttribute can be applied to individual types and methods to make those run at the Critical or SafeCritical levels, with all the restrictions that entails. So, to allow the sandboxed assembly to call the full-trust API assembly, simply add APCTA to the API assembly: [assembly: AllowPartiallyTrustedCallers] and everything works as you expect. The sandboxed dll can call your API dll, and from there communicate with the rest of the application. Conclusion That’s the basics of running a full-trust assembly in a sandboxed appdomain, and allowing a sandboxed assembly to access it. The key is AllowPartiallyTrustedCallersAttribute, which is what lets partially-trusted code call a fully-trusted assembly. However, an assembly with APTCA applied to it means that you have run a full security audit of every type and member in the assembly. If you don’t, then you could inadvertently open a security hole. I’ll be looking at ways this can happen in my next post.

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  • ASP NET Custom Routing

    - by Botem Bao
    I have following patterns /invitation/mission/busstop -- return the list of busstops /invitation/mission/busstop/id -- return a specific busstop /invitation/mission/driver -- return the list of drivers /invitation/mission/driver/id -- return a specific driver /invitation/mission/driver/city/model/limit -- query driver accoring to city, model and age limit ... /invitation/questionair -- return the list of questionairs /invitation/questionair/id -- return a specific questionair /invitation/questionair/create -- create a new questionair /invitation/questionair/update/id -- update a questionair ... I expect the 'invitation' to be controller, and the rest to be action. Each of the above url should corresponds to a dedicated view page. Can anyone help me to design the routes? ===================================================================== I update the patterns, and add my expectation at the end of each url. Any suggest on the url patterns?

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  • Message from Nagios Server

    - by user12213
    Nagios Server is monitoring my Server which hosts Windows Sharepoint. I am getting the following 2 alerts in my inbox from Nagios Server 1. Service: C:\ Drive Space State: CRITICAL Additional Info: CRITICAL - Socket timeout after 10 seconds 2. Service: CPU Load State: CRITICAL Additional Info: CRITICAL - Socket timeout after 10 seconds What do I infer from these?

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  • Porting Oracle Procedure to PostgreSQL

    - by Grasper
    I am porting an Oracle function into Postgres PGPLSQL.. I have been using this guide: http://www.postgresql.org/docs/8.1/static/plpgsql.html CREATE OR REPLACE PROCEDURE DATA_UPDATE (mission NUMBER, task NUMBER) AS BEGIN IF mission IS NOT NULL THEN UPDATE MISSION_OBJECTIVE MO SET (MO.MO_TKR_TOTAL_OFF_SCHEDULED, MO.MO_TKR_TOTAL_RECEIVERS) = (SELECT NVL(SUM(RR.TRQ_FUEL_OFFLOAD),0), NVL(SUM(RR.TRQ_NUMBER_RECEIVERS),0) FROM REFUELING_REQUEST RR, MISSION_REQUEST_PAIRING MRP WHERE MO.MSN_INT_ID = MRP.MSN_INT_ID AND MO.MO_INT_ID = MRP.MO_INT_ID AND MRP.REQ_INT_ID = RR.REQ_INT_ID) WHERE MO.MSN_INT_ID = mission AND MO.MO_INT_ID = task ; END IF ; COMMIT ; END ; I've got it this far: CREATE OR REPLACE FUNCTION DATA_UPDATE (NUMERIC, NUMERIC) RETURNS integer as ' DECLARE mission ALIAS for $1; task ALIAS for $2; BEGIN IF mission IS NOT NULL THEN UPDATE MISSION_OBJECTIVE MO SET (MO.MO_TKR_TOTAL_OFF_SCHEDULED, MO.MO_TKR_TOTAL_RECEIVERS) = (SELECT COALESCE(SUM(RR.TRQ_FUEL_OFFLOAD),0), COALESCE(SUM(RR.TRQ_NUMBER_RECEIVERS),0) FROM REFUELING_REQUEST RR, MISSION_REQUEST_PAIRING MRP WHERE MO.MSN_INT_ID = MRP.MSN_INT_ID AND MO.MO_INT_ID = MRP.MO_INT_ID AND MRP.REQ_INT_ID = RR.REQ_INT_ID) WHERE MO.MSN_INT_ID = mission AND MO.MO_INT_ID = task ; END IF; COMMIT; END; ' LANGUAGE plpgsql; This is the error I get: ERROR: syntax error at or near "SELECT" LINE 1: ...OTAL_OFF_SCHEDULED, MO.MO_TKR_TOTAL_RECEIVERS) = (SELECT COA... I do not know why this isn't working... any ideas?

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  • Critical tools that every Java Developer should have in his toolbelt?

    - by Timur Fanshteyn
    I was trying to compile a list of tools that a good Java Developer should be know of, and keep in his Developer Tool Belt I can think of a few Eclipse Development Environment - There are other IDEs, but you should know how Eclipse of eclipse. JUnit - Java Unit Testing Framework. Of course there are others, but... ANT Maven Soap UI - for testing SOAP endpoints jrat - Java Profiler. I don't know of other good Java profilers Java Decompiler - For when you just have to know what's in the jar file

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  • How to program critical section for reader-writer systems?

    - by Srinivas Nayak
    Hi, Lets say, I have a reader-writer system where reader and writer are concurrently running. 'a' and 'b' are two shared variables, which are related to each other, so modification to them needs to be an atomic operation. A reader-writer system can be of the following types: rr ww r-w r-ww rr-w rr-ww where [ r : single reader rr: multiple reader w : single writer ww: multiple writer ] Now, We can have a read method for a reader and a write method for a writer as follows. I have written them system type wise. rr read_method { read a; read b; } ww write_method { lock(m); write a; write b; unlock(m); } r-w r-ww rr-w rr-ww read_method { lock(m); read a; read b; unlock(m); } write_method { lock(m); write a; write b; unlock(m); } For multiple reader system, shared variable access doesn't need to be atomic. For multiple writer system, shared variable access need to be atomic, so locked with 'm'. But, for system types 3 to 6, is my read_method and write_method correct? How can I improve? Sincerely, Srinivas Nayak

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  • Can I prevent a Linux user space pthread yielding in critical code?

    - by KermitG
    I am working on an user space app for an embedded Linux project using the 2.6.24.3 kernel. My app passes data between two file nodes by creating 2 pthreads that each sleep until a asynchronous IO operation completes at which point it wakes and runs a completion handler. The completion handlers need to keep track of how many transfers are pending and maintain a handful of linked lists that one thread will add to and the other will remove. // sleep here until events arrive or time out expires for(;;) { no_of_events = io_getevents(ctx, 1, num_events, events, &timeout); // Process each aio event that has completed or thrown an error for (i=0; i<no_of_events; i++) { // Get pointer to completion handler io_complete = (io_callback_t) events[i].data; // Get pointer to data object iocb = (struct iocb *) events[i].obj; // Call completion handler and pass it the data object io_complete(ctx, iocb, events[i].res, events[i].res2); } } My question is this... Is there a simple way I can prevent the currently active thread from yielding whilst it runs the completion handler rather than going down the mutex/spin lock route? Or failing that can Linux be configured to prevent yielding a pthread when a mutex/spin lock is held?

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  • Rhythmbox is crashing on start

    - by Kristal
    I'm using ubuntu 10.10 and until about 3 days ago rhythmbox worked fine but now when I start it, it opens, then after 4 second it crashes. When running it from terminal I get this: ~$ rhythmbox (rhythmbox:27420): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed ** Message: pygobject_register_sinkfunc is deprecated (GstObject) (rhythmbox:27420): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed Segmentation fault and then rhythmbox closes. What to do? =\ Edit: Disabled most of the plugins and it's not crashing now, but i still get when running from terminal (rhythmbox:27420): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed ** Message: pygobject_register_sinkfunc is deprecated (GstObject) (rhythmbox:27420): GLib-GObject-CRITICAL **: g_object_unref: assertion `G_IS_OBJECT (object)' failed should I worry?

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  • Nagios state transition and event handler issue

    - by Dattatray
    We are using Nagios to check duplicate processes. define service { use local-service host_name xxx service_description xxx Duplicate Processes check_interval 1 max_check_attempts 1 contact_groups admins event_handler restart-dependent-processes check_command check_procs_duplicate!2!3!2!2!2 } check_procs_duplicate checks if there are any duplicate processes and returns the state - e.g. CRITICAL. The event handler kills the duplicate processes and it's dependent processes and starts one instance of the process and dependent process. At the end of this again Nagios checks if there are any duplicate processes and sets the state accordingly - OK/WARNING/CRITICAL. The event handler takes more time to start the processes and during this time if someone manually starts the process, the state will remain in CRITICAL itself. During the next interval, Nagios will again check for duplicate processes and it will find it again CRITICAL. The event handler will not get executed now, as the previos and current both the states are CRITICAL. Any pointers about how to fix this issue?

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  • SBS 2003 requires logon for share

    - by Mission
    Hi, Win 2003 SBS has started requiring password for a domain user. It's weird because it doesn't requires it every time...sometimes it will work (automatic shares through logon script) and sometimes it won't...lets the user in after 2-3 tries (wrong password errors) and the loads the share with the same pass... Thanks!

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  • Thread Synchronisation 101

    - by taspeotis
    Previously I've written some very simple multithreaded code, and I've always been aware that at any time there could be a context switch right in the middle of what I'm doing, so I've always guarded access the shared variables through a CCriticalSection class that enters the critical section on construction and leaves it on destruction. I know this is fairly aggressive and I enter and leave critical sections quite frequently and sometimes egregiously (e.g. at the start of a function when I could put the CCriticalSection inside a tighter code block) but my code doesn't crash and it runs fast enough. At work my multithreaded code needs to be a tighter, only locking/synchronising at the lowest level needed. At work I was trying to debug some multithreaded code, and I came across this: EnterCriticalSection(&m_Crit4); m_bSomeVariable = true; LeaveCriticalSection(&m_Crit4); Now, m_bSomeVariable is a Win32 BOOL (not volatile), which as far as I know is defined to be an int, and on x86 reading and writing these values is a single instruction, and since context switches occur on an instruction boundary then there's no need for synchronising this operation with a critical section. I did some more research online to see whether this operation did not need synchronisation, and I came up with two scenarios it did: The CPU implements out of order execution or the second thread is running on a different core and the updated value is not written into RAM for the other core to see; and The int is not 4-byte aligned. I believe number 1 can be solved using the "volatile" keyword. In VS2005 and later the C++ compiler surrounds access to this variable using memory barriers, ensuring that the variable is always completely written/read to the main system memory before using it. Number 2 I cannot verify, I don't know why the byte alignment would make a difference. I don't know the x86 instruction set, but does mov need to be given a 4-byte aligned address? If not do you need to use a combination of instructions? That would introduce the problem. So... QUESTION 1: Does using the "volatile" keyword (implicity using memory barriers and hinting to the compiler not to optimise this code) absolve a programmer from the need to synchronise a 4-byte/8-byte on x86/x64 variable between read/write operations? QUESTION 2: Is there the explicit requirement that the variable be 4-byte/8-byte aligned? I did some more digging into our code and the variables defined in the class: class CExample { private: CRITICAL_SECTION m_Crit1; // Protects variable a CRITICAL_SECTION m_Crit2; // Protects variable b CRITICAL_SECTION m_Crit3; // Protects variable c CRITICAL_SECTION m_Crit4; // Protects variable d // ... }; Now, to me this seems excessive. I thought critical sections synchronised threads between a process, so if you've got one you can enter it and no other thread in that process can execute. There is no need for a critical section for each variable you want to protect, if you're in a critical section then nothing else can interrupt you. I think the only thing that can change the variables from outside a critical section is if the process shares a memory page with another process (can you do that?) and the other process starts to change the values. Mutexes would also help here, named mutexes are shared across processes, or only processes of the same name? QUESTION 3: Is my analysis of critical sections correct, and should this code be rewritten to use mutexes? I have had a look at other synchronisation objects (semaphores and spinlocks), are they better suited here? QUESTION 4: Where are critical sections/mutexes/semaphores/spinlocks best suited? That is, which synchronisation problem should they be applied to. Is there a vast performance penalty for choosing one over the other? And while we're on it, I read that spinlocks should not be used in a single-core multithreaded environment, only a multi-core multithreaded environment. So, QUESTION 5: Is this wrong, or if not, why is it right? Thanks in advance for any responses :)

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  • Monitor your Hard Drive’s Health with Acronis Drive Monitor

    - by Matthew Guay
    Are you worried that your computer’s hard drive could die without any warning?  Here’s how you can keep tabs on it and get the first warning signs of potential problems before you actually lose your critical data. Hard drive failures are one of the most common ways people lose important data from their computers.  As more of our memories and important documents are stored digitally, a hard drive failure can mean the loss of years of work.  Acronis Drive Monitor helps you avert these disasters by warning you at the first signs your hard drive may be having trouble.  It monitors many indicators, including heat, read/write errors, total lifespan, and more. It then notifies you via a taskbar popup or email that problems have been detected.  This early warning lets you know ahead of time that you may need to purchase a new hard drive and migrate your data before it’s too late. Getting Started Head over to the Acronis site to download Drive Monitor (link below).  You’ll need to enter your name and email, and then you can download this free tool. Also, note that the download page may ask if you want to include a trial of their for-pay backup program.  If you wish to simply install the Drive Monitor utility, click Continue without adding. Run the installer when the download is finished.  Follow the prompts and install as normal. Once it’s installed, you can quickly get an overview of your hard drives’ health.  Note that it shows 3 categories: Disk problems, Acronis backup, and Critical Events.  On our computer, we had Seagate DiskWizard, an image backup utility based on Acronis Backup, installed, and Acronis detected it. Drive Monitor stays running in your tray even when the application window is closed.  It will keep monitoring your hard drives, and will alert you if there’s a problem. Find Detailed Information About Your Hard Drives Acronis’ simple interface lets you quickly see an overview of how the drives on your computer are performing.  If you’d like more information, click the link under the description.  Here we see that one of our drives have overheated, so click Show disks to get more information. Now you can select each of your drives and see more information about them.  From the Disk overview tab that opens by default, we see that our drive is being monitored, has been running for a total of 368 days, and that it’s health is good.  However, it is running at 113F, which is over the recommended max of 107F.   The S.M.A.R.T. parameters tab gives us more detailed information about our drive.  Most users wouldn’t know what an accepted value would be, so it also shows the status.  If the value is within the accepted parameters, it will report OK; otherwise, it will show that has a problem in this area. One very interesting piece of information we can see is the total number of Power-On Hours, Start/Stop Count, and Power Cycle Count.  These could be useful indicators to check if you’re considering purchasing a second hand computer.  Simply load this program, and you’ll get a better view of how long it’s been in use. Finally, the Events tab shows each time the program gave a warning.  We can see that our drive, which had been acting flaky already, is routinely overheating even when our other hard drive was running in normal temperature ranges. Monitor Acronis Backups And Critical Errors In addition to monitoring critical stats of your hard drives, Acronis Drive Monitor also keeps up with the status of your backup software and critical events reported by Windows.  You can access these from the front page, or via the links on the left hand sidebar.  If you have any edition of any Acronis Backup product installed, it will show that it was detected.  Note that it can only monitor the backup status of the newest versions of Acronis Backup and True Image. If no Acronis backup software was installed, it will show a warning that the drive may be unprotected and will give you a link to download Acronis backup software.   If you have another backup utility installed that you wish to monitor yourself, click Configure backup monitoring, and then disable monitoring on the drives you’re monitoring yourself. Finally, you can view any detected Critical events from the Critical events tab on the left. Get Emailed When There’s a Problem One of Drive Monitor’s best features is the ability to send you an email whenever there’s a problem.  Since this program can run on any version of Windows, including the Server and Home Server editions, you can use this feature to stay on top of your hard drives’ health even when you’re not nearby.  To set this up, click Options in the top left corner. Select Alerts on the left, and then click the Change settings link to setup your email account. Enter the email address which you wish to receive alerts, and a name for the program.  Then, enter the outgoing mail server settings for your email.  If you have a Gmail account, enter the following information: Outgoing mail server (SMTP): smtp.gmail.com Port: 587 Username and Password: Your gmail address and password Check the Use encryption box, and then select TLS from the encryption options.   It will now send a test message to your email account, so check and make sure it sent ok. Now you can choose to have the program automatically email you when warnings and critical alerts appear, and also to have it send regular disk status reports.   Conclusion Whether you’ve got a brand new hard drive or one that’s seen better days, knowing the real health of your it is one of the best ways to be prepared before disaster strikes.  It’s no substitute for regular backups, but can help you avert problems.  Acronis Drive Monitor is a nice tool for this, and although we wish it wasn’t so centered around their backup offerings, we still found it a nice tool. Link Download Acronis Drive Monitor (registration required) Similar Articles Productive Geek Tips Quick Tip: Change Monitor Timeout From Command LineAnalyze and Manage Hard Drive Space with WinDirStatMonitor CPU, Memory, and Disk IO In Windows 7 with Taskbar MetersDefrag Multiple Hard Drives At Once In WindowsFind Your Missing USB Drive on Windows XP TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips HippoRemote Pro 2.2 Xobni Plus for Outlook All My Movies 5.9 CloudBerry Online Backup 1.5 for Windows Home Server Windows 7’s WordPad is Actually Good Greate Image Viewing and Management with Zoner Photo Studio Free Windows Media Player Plus! – Cool WMP Enhancer Get Your Team’s World Cup Schedule In Google Calendar Backup Drivers With Driver Magician TubeSort: YouTube Playlist Organizer

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  • Rspec Faker has_one fail in view

    - by Victor Martins
    I' trying to fix this for hours... I have this on a controller rspec test: it "show action should render show template" do task = Task.make task.mission = Mission.make get :show, :id => task response.should render_template(:show) end But it fails rendering the view because of this: <%=h @task.mission.name %> I don't get it... :/

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  • Implications of Java 6 End of Public Updates for EBS Users

    - by Steven Chan (Oracle Development)
    The Support Roadmap for Oracle Java is published here: Oracle Java SE Support Roadmap The latest updates to that page (as of Sept. 19, 2012) state (emphasis added): Java SE 6 End of Public Updates Notice After February 2013, Oracle will no longer post updates of Java SE 6 to its public download sites. Existing Java SE 6 downloads already posted as of February 2013 will remain accessible in the Java Archive on Oracle Technology Network. Developers and end-users are encouraged to update to more recent Java SE versions that remain available for public download. For enterprise customers, who need continued access to critical bug fixes and security fixes as well as general maintenance for Java SE 6 or older versions, long term support is available through Oracle Java SE Support . What does this mean for Oracle E-Business Suite users? EBS users fall under the category of "enterprise users" above.  Java is an integral part of the Oracle E-Business Suite technology stack, so EBS users will continue to receive Java SE 6 updates after February 2013. In other words, nothing will change for EBS users after February 2013.  EBS users will continue to receive critical bug fixes and security fixes as well as general maintenance for Java SE 6. These Java SE 6 updates will be made available to EBS users for the Extended Support periods documented in the Oracle Lifetime Support policy document for Oracle Applications (PDF): EBS 11i Extended Support ends November 2013 EBS 12.0 Extended Support ends January 2015 EBS 12.1 Extended Support ends December 2018 Will EBS users be forced to upgrade to JRE 7 for Windows desktop clients? No. This upgrade will be highly recommended but currently remains optional. JRE 6 will be available to Windows users to run with EBS for the duration of your respective EBS Extended Support period.  Updates will be delivered via My Oracle Support, where you can continue to receive critical bug fixes and security fixes as well as general maintenance for JRE 6 desktop clients.  The certification of Oracle E-Business Suite with JRE 7 (for desktop clients accessing EBS Forms-based content) is in its final stages.  If you plan to upgrade your EBS desktop clients to JRE 7 when that certification is released, you can get a head-start on that today. Coexistence of JRE 6 and JRE 7 on Windows desktops The upgrade to JRE 7 will be highly recommended for EBS users, but some users may need to run both JRE 6 and 7 on their Windows desktops for reasons unrelated to the E-Business Suite. Most EBS configurations with IE and Firefox use non-static versioning by default. JRE 7 will be invoked instead of JRE 6 if both are installed on a Windows desktop. For more details, see "Appendix B: Static vs. Non-static Versioning and Set Up Options" in Notes 290801.1 and 393931.1. Applying Updates to JRE 6 and JRE 7 to Windows desktops Auto-update will keep JRE 7 up-to-date for Windows users with JRE 7 installed. Auto-update will only keep JRE 7 up-to-date for Windows users with both JRE 6 and 7 installed.  JRE 6 users are strongly encouraged to apply the latest Critical Patch Updates as soon as possible after each release. The Jave SE CPUs will be available via My Oracle Support.  EBS users can find more information about JRE 6 and 7 updates here: Information Center: Installation & Configuration for Oracle Java SE (Note 1412103.2) The dates for future Java SE CPUs can be found on the Critical Patch Updates, Security Alerts and Third Party Bulletin.  An RSS feed is available on that site for those who would like to be kept up-to-date. What will Mac users need? Oracle will provide updates to JRE 7 for Mac OS X users. EBS users running Macs will need to upgrade to JRE 7 to receive JRE updates. The certification of Oracle E-Business Suite with JRE 7 for Mac-based desktop clients accessing EBS Forms-based content is underway. Mac users waiting for that certification may find this article useful: How to Reenable Apple Java 6 Plug-in for Mac EBS Users Will EBS users be forced to upgrade to JDK 7 for EBS application tier servers? No. This upgrade will be highly recommended but will be optional for EBS application tier servers running on Windows, Linux, and Solaris.  You can choose to remain on JDK 6 for the duration of your respective EBS Extended Support period.  If you remain on JDK 6, you will continue to receive critical bug fixes and security fixes as well as general maintenance for JDK 6. The certification of Oracle E-Business Suite with JDK 7 for EBS application tier servers on Windows, Linux, and Solaris as well as other platforms such as IBM AIX and HP-UX is planned.  Customers running platforms other than Windows, Linux, and Solaris should refer to their Java vendors's sites for more information about their support policies. Related Articles Planning Bulletin for JRE 7: What EBS Customers Can Do Today EBS 11i and 12.1 Support Timeline Changes Frequently Asked Questions about Latest EBS Support Changes Critical Patch Updates During EBS 11i Exception to Sustaining Support Period

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  • Performance and Optimization Isn’t Evil

    - by Reed
    Donald Knuth is a fairly amazing guy.  I consider him one of the most influential contributors to computer science of all time.  Unfortunately, most of the time I hear his name, I cringe.  This is because it’s typically somebody quoting a small portion of one of his famous statements on optimization: “premature optimization is the root of all evil.” I mention that this is only a portion of the entire quote, and, as such, I feel that Knuth is being quoted out of context.  Optimization is important.  It is a critical part of every software development effort, and should never be ignored.  A developer who ignores optimization is not a professional.  Every developer should understand optimization – know what to optimize, when to optimize it, and how to think about code in a way that is intelligent and productive from day one. I want to start by discussing my own, personal motivation here.  I recently wrote about a performance issue I ran across, and was slammed by multiple comments and emails that effectively boiled down to: “You’re an idiot.  Premature optimization is the root of all evil.  This doesn’t matter.”  It didn’t matter that I discovered this while measuring in a profiler, and that it was a portion of my code base that can take “many hours to complete.”  Even so, multiple people instantly jump to “it’s premature – it doesn’t matter.” This is a common thread I see.  For example, StackOverflow has many pages of posts with answers that boil down to (mis)quoting Knuth.  In fact, just about any question relating to a performance related issue gets this quote thrown at it immediately – whether it deserves it or not.  That being said, I did receive some positive comments and emails as well.  Many people want to understand how to optimize their code, approaches to take, tools and techniques they can use, and any other advice they can discover. First, lets get back to Knuth – I mentioned before that Knuth is being quoted out of context.  Lets start by looking at the entire quote from his 1974 paper Structured Programming with go to Statements: “We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil. Yet we should not pass up our opportunities in that critical 3%. A good programmer will not be lulled into complacency by such reasoning, he will be wise to look carefully at the critical code; but only after that code has been identified.” Ironically, if you read Knuth’s original paper, this statement was made in the middle of a discussion of how Knuth himself had changed how he approaches optimization.  It was never a statement saying “don’t optimize”, but rather, “optimizing intelligently provides huge advantages.”  His approach had three benefits: “a) it doesn’t take long” … “b) the payoff is real”, c) you can “be less efficient in the other parts of my programs, which therefore are more readable and more easily written and debugged.” Looking at Knuth’s premise here, and reading that section of his paper, really leads to a few observations: Optimization is important  “he will be wise to look carefully at the critical code” Normally, 3% of your code – three lines out of every 100 you write, are “critical code” and will require some optimization: “we should not pass up our opportunities in that critical 3%” Optimization, if done well, should not be time consuming: “it doesn’t take long” Optimization, if done correctly, provides real benefits: “the payoff is real” None of this is new information.  People who care about optimization have been discussing this for years – for example, Rico Mariani’s Designing For Performance (a fantastic article) discusses many of the same issues very intelligently. That being said, many developers seem unable or unwilling to consider optimization.  Many others don’t seem to know where to start.  As such, I’m going to spend some time writing about optimization – what is it, how should we think about it, and what can we do to improve our own code.

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  • i don't receive mail notification...Nagios Core 4

    - by alessio
    I have a problem with automatically mail notification in Nagios Core 4 installed on ubuntu 12 .04 lts server... i have tried to send mail with nagios user and root user with the command: echo "test" | mail -s "test mail" [email protected] and i received mail correctly... but i don't receive any automatically mail notification... i don't know how can i do to resolve this issue! :( these are my configuration files (commands.cfg, contacts.cfg, nagios.log, mail.log): commands.cfg (the path /usr/bin/mail is the right path): # 'notify-host-by-email' command definition define command{ command_name notify-host-by-email command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$ } # 'notify-service-by-email' command definition define command{ command_name notify-service-by-email command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$\n" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$ } # 'process-host-perfdata' command definition define command{ command_name process-host-perfdata command_line /usr/bin/printf "%b" "$LASTHOSTCHECK$\t$HOSTNAME$\t$HOSTSTATE$\t$HOSTATTEMPT$\t$HOSTSTATETYPE$\t$HOSTEXECUTIONTIME$\t$HOSTOUTPUT$\t$HOSTPERFDATA$\n" >> /usr/local/nagios/var/host-perfdata.out } # 'process-service-perfdata' command definition define command{ command_name process-service-perfdata command_line /usr/bin/printf "%b" "$LASTSERVICECHECK$\t$HOSTNAME$\t$SERVICEDESC$\t$SERVICESTATE$\t$SERVICEATTEMPT$\t$SERVICESTATETYPE$\t$SERVICEEXECUTIONTIME$\t$SERVICELATENCY$\t$SERVICEOUTPUT$\t$SERVICEPERFDATA$\n" >> /usr/local/nagios/var/service-perfdata.out } contacts.cfg: define contact{ contact_name supporto alias Supporto Clienti DEA service_notification_period 24x7 host_notification_period 24x7 service_notification_options w,u,c,r host_notification_options d,r service_notification_commands notify-service-by-email host_notification_commands notify-host-by-email email [email protected] } define contactgroup{ contactgroup_name admins alias Nagios Administrators members supporto } nagios.log: [1401871412] SERVICE ALERT: fileserver;Current Users;OK;SOFT;2;USERS OK - 1 users currently logged in [1401871953] SERVICE ALERT: backups;Nagios Status;WARNING;SOFT;1;NAGIOS WARNING: 36 processes, status log updated 541 seconds ago [1401872133] SERVICE ALERT: backups;Nagios Status;OK;SOFT;2;NAGIOS OK: 36 processes, status log updated 180 seconds ago [1401872321] SERVICE ALERT: posta;Swap Usage;CRITICAL;SOFT;1;CRITICAL - Plugin timed out after 10 seconds [1401872322] SERVICE ALERT: fileserver;Current Users;CRITICAL;SOFT;1;CRITICAL - Plugin timed out after 10 seconds [1401872420] SERVICE ALERT: archivio;Disk Space;CRITICAL;SOFT;1;CRITICAL - Plugin timed out after 10 seconds [1401872492] SERVICE ALERT: fileserver;Current Users;OK;SOFT;2;USERS OK - 1 users currently logged in [1401872492] SERVICE ALERT: posta;Swap Usage;OK;SOFT;2;SWAP OK: 100% free (1984 MB out of 1984 MB) [1401872590] SERVICE ALERT: archivio;Disk Space;OK;SOFT;2;DISK OK [1401872931] Auto-save of retention data completed successfully. [1401873333] SERVICE ALERT: backups;Nagios Status;WARNING;SOFT;1;NAGIOS WARNING: 36 processes, status log updated 402 seconds ago [1401873513] SERVICE ALERT: backups;Nagios Status;OK;SOFT;2;NAGIOS OK: 36 processes, status log updated 180 seconds ago mail.log (i think that the problem is here but i don't know how to resolve it): Jun 4 10:00:01 backups sm-msp-queue[6109]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 10:01:01 backups sm-msp-queue[6109]: unable to qualify my own domain name (backups) -- using short name Jun 4 10:20:01 backups sm-msp-queue[7247]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 10:21:01 backups sm-msp-queue[7247]: unable to qualify my own domain name (backups) -- using short name Jun 4 10:40:01 backups sm-msp-queue[8327]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 10:41:01 backups sm-msp-queue[8327]: unable to qualify my own domain name (backups) -- using short name Jun 4 11:00:01 backups sm-msp-queue[9549]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 11:01:01 backups sm-msp-queue[9549]: unable to qualify my own domain name (backups) -- using short name Jun 4 11:20:01 backups sm-msp-queue[10678]: My unqualified host name (backups) unknown; sleeping for retry Jun 4 11:21:01 backups sm-msp-queue[10678]: unable to qualify my own domain name (backups) -- using short name i'm at the last step and i want to finish this Nagios Core! :) Any help be appreciate!:) host definition (this host have the disk almost full and it is in hard state but non notification) : define host{ use generic-host ; Name of host template to use host_name posta alias Server Posta ESA address 10.10.2.102 parents xen1, xen2 icon_image redhat.png statusmap_image redhat.gd2 } service definition: define service{ use generic-service host_name xen1, maestro, xen2, posta, nas002, serv2, esasrvmi02, esaubuntumi service_description Disk Space check_command ssh_all_disks!10%!5% } Notification is allowed for the contact definition you gave, but is it also allowed at the the service level ? sorry but i don't understand this thing! :(

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