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• Designing An ACL Based Permission System

  - by ryanzec

  I am trying to create a permissions system where everything is going to be stored in MySQL (or some database) and pulled using PHP for a project management system I am building.  I am right now trying to do it is an ACL kind of way.  There are a number key features I want to be able to support: 1.  Being able to assign permissions without being tied to a specific object. The reason for this is that I want to be able to selectively show/hide elements of the UI based on permissions at a point where I am not directly looking at a domain object instance.  For instance, a button to create a new project should only should only be shown to users that have the pm.project.create permission but obviously you can assign a create permission to an domain object instance (as it is already created). 2.  Not have to assign permissions for every single object. Obviously creating permissions entries for every single object (projects, tickets, comments, etc…) would become a nightmare to maintain so I want to have some level of permission inheritance. *3.  Be able to filter queries based on permissions. This would be a really nice to have but I am not sure if it is possible.  What I mean by this is say I have a page that list all projects.  I want the query that pulls all projects to incorporate the ACL so that it would not show projects that the current user does not have pm.project.read access to.  This would have to be incorporated into the main query as if it is a process that is done after that main query (which I know I could do) certain features like pagination become much more difficult. Right now this is my basic design for the tables: AclEntities id - the primary key key - the unique identifier for the domain object (usually the primary key of that object) parentId - the parent of the domain object (like the project object if this was a ticket object) aclDomainObjectId - metadata about the domain object AclDomainObjects id - primary key title - simple string to unique identify the domain object(ie. project, ticket, comment, etc…) fullyQualifiedClassName - the fully qualified class name for use in code (I am using namespaces) There would also be tables mapping AclEntities to Users and UserGroups. I also have this interface that all acl entity based object have to implement: IAclEntity getAclKey() - to the the unique key for this specific instance of the acl domain object (generally return the primary key or a concatenated string of a composite primary key) getAclTitle() - to get the unique title for the domain object (generally just returning a static string) getAclDisplayString() - get the string that represents this entity (generally one or more field on the object) getAclParentEntity() - get the parent acl entity object (or null if no parent) getAclEntity() - get the acl enitty object for this instance of the domain object (or null if one has not been created yet) hasPermission($permissionString, $user = null) - whether or not the user has the permission for this instance of the domain object static getFromAclEntityId($aclEntityId) - get a specific instance of the domain object from an acl entity id. Do any of these features I am looking for seems hard to support or are just way off base? Am I missing or not taking in account anything in my implementation? Is performance something I should keep in mind?

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• Help understand GLSL directional light on iOS (left handed coord system)

  - by Robse

  I now have changed from GLKBaseEffect to a own shader implementation. I have a shader management, which compiles and applies a shader to the right time and does some shader setup like lights. Please have a look at my vertex shader code. Now, light direction should be provided in eye space, but I think there is something I don't get right. After I setup my view with camera I save a lightMatrix to transform the light from global space to eye space. My modelview and projection setup: - (void)setupViewWithWidth:(int)width height:(int)height camera:(N3DCamera *)aCamera { aCamera.aspect = (float)width / (float)height; float aspect = aCamera.aspect; float far = aCamera.far; float near = aCamera.near; float vFOV = aCamera.fieldOfView; float top = near * tanf(M_PI * vFOV / 360.0f); float bottom = -top; float right = aspect * top; float left = -right; // projection GLKMatrixStackLoadMatrix4(projectionStack, GLKMatrix4MakeFrustum(left, right, bottom, top, near, far)); // identity modelview GLKMatrixStackLoadMatrix4(modelviewStack, GLKMatrix4Identity); // switch to left handed coord system (forward = z+) GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeScale(1, 1, -1)); // transform camera GLKMatrixStackMultiplyMatrix4(modelviewStack, GLKMatrix4MakeWithMatrix3(GLKMatrix3Transpose(aCamera.orientation))); GLKMatrixStackTranslate(modelviewStack, -aCamera.position.x, -aCamera.position.y, -aCamera.position.z); } - (GLKMatrix4)modelviewMatrix { return GLKMatrixStackGetMatrix4(modelviewStack); } - (GLKMatrix4)projectionMatrix { return GLKMatrixStackGetMatrix4(projectionStack); } - (GLKMatrix4)modelviewProjectionMatrix { return GLKMatrix4Multiply([self projectionMatrix], [self modelviewMatrix]); } - (GLKMatrix3)normalMatrix { return GLKMatrix3InvertAndTranspose(GLKMatrix4GetMatrix3([self modelviewProjectionMatrix]), NULL); } After that, I save the lightMatrix like this: [self.renderer setupViewWithWidth:view.drawableWidth height:view.drawableHeight camera:self.camera]; self.lightMatrix = [self.renderer modelviewProjectionMatrix]; And just before I render a 3d entity of the scene graph, I setup the light config for its shader with the lightMatrix like this: - (N3DLight)transformedLight:(N3DLight)light transformation:(GLKMatrix4)matrix { N3DLight transformedLight = N3DLightMakeDisabled(); if (N3DLightIsDirectional(light)) { GLKVector3 direction = GLKVector3MakeWithArray(GLKMatrix4MultiplyVector4(matrix, light.position).v); direction = GLKVector3Negate(direction); // HACK -> TODO: get lightMatrix right! transformedLight = N3DLightMakeDirectional(direction, light.diffuse, light.specular); } else { ... } return transformedLight; } You see the line, where I negate the direction!? I can't explain why I need to do that, but if I do, the lights are correct as far as I can tell. Please help me, to get rid of the hack. I'am scared that this has something to do, with my switch to left handed coord system. My vertex shader looks like this: attribute highp vec4 inPosition; attribute lowp vec4 inNormal; ... uniform highp mat4 MVP; uniform highp mat4 MV; uniform lowp mat3 N; uniform lowp vec4 constantColor; uniform lowp vec4 ambient; uniform lowp vec4 light0Position; uniform lowp vec4 light0Diffuse; uniform lowp vec4 light0Specular; varying lowp vec4 vColor; varying lowp vec3 vTexCoord0; vec4 calcDirectional(vec3 dir, vec4 diffuse, vec4 specular, vec3 normal) { float NdotL = max(dot(normal, dir), 0.0); return NdotL * diffuse; } ... vec4 calcLight(vec4 pos, vec4 diffuse, vec4 specular, vec3 normal) { if (pos.w == 0.0) { // Directional Light return calcDirectional(normalize(pos.xyz), diffuse, specular, normal); } else { ... } } void main(void) { // position highp vec4 position = MVP * inPosition; gl_Position = position; // normal lowp vec3 normal = inNormal.xyz / inNormal.w; normal = N * normal; normal = normalize(normal); // colors vColor = constantColor * ambient; // add lights vColor += calcLight(light0Position, light0Diffuse, light0Specular, normal); ... }

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• Changing the Operating System with only Ubuntu installed

  - by Games Brainiac

  I really wanted to dive into the world of Open Source operating systems, so I downloaded the latest version of Ubuntu (13.10), and installed it on a clean(no operating system installed, absolutely nothing) Lenovo ThinkPad machine. After a few days, I wanted to try out a different Operating System (Elementary OS). I downloaded the ISO file, burned it to a USB, tested that the USB booted from a different computer (I have 2, one is the Lenovo, the other a HP). I was able to get the bootscreen, and everything worked like a charm after I set the BIOS to boot from USB Disk Drive instead of HD. After this, I went back to Lenovo, and tried to open up the boot menu, by pressing F12, so that I could load from a temporary device. To my surprise, nothing but the HD was listed. There was no Optical Drive, No USB Drive, absolutely nothing. So, I thought that these devices were probably disabled. So I went into my BIOS and checked to see what was the case. I saw that all my devices were enabled. USB and all the other devices such as network cable and the rest were all enabled. So, I thought this probably had something to do wit UEFI and Legacy Boot options. So, I made sure that both were enabled. This did not solve the problem either. Again, I got nothing but the option to boot from my Hard Disk. I thought the USB had to be at fault. I tried different ports, but to no avail. Next, I tried with a Live CD, which had Ubuntu on it. This failed too. I simply could not boot from anything other than my hard disk. Okay, so at this point, I was pretty desperate, so I installed Boot-Repair through: sudo add-apt-repository ppa:yannubuntu/boot-repair sudo apt-get update sudo apt-get install boot-repair What this did is lead me to GRUB. Ideally, its just a screen that gives me the option to load from Ubuntu or Advanced Settings. The Advanced settings had nothing but Ubuntu options in it. So, I kept on pressing ESC and that led me to the the grub console, and thats where I am right now with my Lenovo. I've also tried updating the BIOS, but Lenovo only has packages for Red Hat and Windows. So, a dead end there too. Right now, I need to know if there is any way that I can just delete everything from my Lenovo? I want to revert it back to its blank factory condition. How can I achieve this? I have tried to elaborate my problem as best I could. If there is any important information that I've missed out, please do not hesitate to leave a comment. I would have included some screen shots, but BIOS screen shots are a little hard to manage. However, I can provide a camera Image of the boot screen if needed (doing that as we speak).

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• C# Web Service gets stuck waiting for lock, does not return

  - by blue

  We have a C#(2.0) application which talks to our server(in java) via web services. Lately we have started seeing following behavior in (ONLY)one of our lab machines(XP): Once in a while(every few days), one of the webservice request will just get stuck, will not return or timeout. Following is the stacktrace where it seem to be stuck. Have no clue what is going on here. Any pointer would be of great help. ESP EIP 05eceeec 7c90eb94 [GCFrame: 05eceeec] 05ecefbc 7c90eb94 [HelperMethodFrame_1OBJ: 05ecefbc] System.Threading.Monitor.Enter(System.Object) 05ecf014 7a5b0034 System.Net.ConnectionGroup.Disassociate(System.Net.Connection) 05ecf040 7a5aeaa7 System.Net.Connection.PrepareCloseConnectionSocket(System.Net.ConnectionReturnResult ByRef) 05ecf0a4 7a5ac0e1 System.Net.Connection.ReadStartNextRequest(System.Net.WebRequest, System.Net.ConnectionReturnResult ByRef) 05ecf0e8 7a5b1119 System.Net.ConnectStream.CallDone(System.Net.ConnectionReturnResult) 05ecf0fc 7a5b3b5a System.Net.ConnectStream.ReadChunkedSync(Byte[], Int32, Int32) 05ecf114 7a5b2b90 System.Net.ConnectStream.ReadWithoutValidation(Byte[], Int32, Int32, Boolean) 05ecf160 7a5b29cc System.Net.ConnectStream.Read(Byte[], Int32, Int32) 05ecf1a0 79473cab System.IO.StreamReader.ReadBuffer(Char[], Int32, Int32, Boolean ByRef) 05ecf1c4 79473bd6 System.IO.StreamReader.Read(Char[], Int32, Int32) 05ecf1e8 69c29119 System.Xml.XmlTextReaderImpl.ReadData() 05ecf1f8 69c2ad70 System.Xml.XmlTextReaderImpl.ParseDocumentContent() 05ecf20c 69c292d7 System.Xml.XmlTextReaderImpl.Read() 05ecf21c 69c2929d System.Xml.XmlTextReader.Read() 05ecf220 6991b3e7 System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(System.Web.Services.Protocols.SoapClientMessage, System.Net.WebResponse, System.IO.Stream, Boolean) 05ecf268 69919ed1 System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(System.String, System.Object[])

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• A Communication System for XAML Applications

  - by psheriff

  In any application, you want to keep the coupling between any two or more objects as loose as possible. Coupling happens when one class contains a property that is used in another class, or uses another class in one of its methods. If you have this situation, then this is called strong or tight coupling. One popular design pattern to help with keeping objects loosely coupled is called the Mediator design pattern. The basics of this pattern are very simple; avoid one object directly talking to another object, and instead use another class to mediate between the two. As with most of my blog posts, the purpose is to introduce you to a simple approach to using a message broker, not all of the fine details. IPDSAMessageBroker Interface As with most implementations of a design pattern, you typically start with an interface or an abstract base class. In this particular instance, an Interface will work just fine. The interface for our Message Broker class just contains a single method “SendMessage” and one event “MessageReceived”. public delegate void MessageReceivedEventHandler( object sender, PDSAMessageBrokerEventArgs e); public interface IPDSAMessageBroker{  void SendMessage(PDSAMessageBrokerMessage msg);   event MessageReceivedEventHandler MessageReceived;} PDSAMessageBrokerMessage Class As you can see in the interface, the SendMessage method requires a type of PDSAMessageBrokerMessage to be passed to it. This class simply has a MessageName which is a ‘string’ type and a MessageBody property which is of the type ‘object’ so you can pass whatever you want in the body. You might pass a string in the body, or a complete Customer object. The MessageName property will help the receiver of the message know what is in the MessageBody property. public class PDSAMessageBrokerMessage{  public PDSAMessageBrokerMessage()  {  }   public PDSAMessageBrokerMessage(string name, object body)  {    MessageName = name;    MessageBody = body;  }   public string MessageName { get; set; }   public object MessageBody { get; set; }} PDSAMessageBrokerEventArgs Class As our message broker class will be raising an event that others can respond to, it is a good idea to create your own event argument class. This class will inherit from the System.EventArgs class and add a couple of additional properties. The properties are the MessageName and Message. The MessageName property is simply a string value. The Message property is a type of a PDSAMessageBrokerMessage class. public class PDSAMessageBrokerEventArgs : EventArgs{  public PDSAMessageBrokerEventArgs()  {  }   public PDSAMessageBrokerEventArgs(string name,     PDSAMessageBrokerMessage msg)  {    MessageName = name;    Message = msg;  }   public string MessageName { get; set; }   public PDSAMessageBrokerMessage Message { get; set; }} PDSAMessageBroker Class Now that you have an interface class and a class to pass a message through an event, it is time to create your actual PDSAMessageBroker class. This class implements the SendMessage method and will also create the event handler for the delegate created in your Interface. public class PDSAMessageBroker : IPDSAMessageBroker{  public void SendMessage(PDSAMessageBrokerMessage msg)  {    PDSAMessageBrokerEventArgs args;     args = new PDSAMessageBrokerEventArgs(      msg.MessageName, msg);     RaiseMessageReceived(args);  }   public event MessageReceivedEventHandler MessageReceived;   protected void RaiseMessageReceived(    PDSAMessageBrokerEventArgs e)  {    if (null != MessageReceived)      MessageReceived(this, e);  }} The SendMessage method will take a PDSAMessageBrokerMessage object as an argument. It then creates an instance of a PDSAMessageBrokerEventArgs class, passing to the constructor two items: the MessageName from the PDSAMessageBrokerMessage object and also the object itself. It may seem a little redundant to pass in the message name when that same message name is part of the message, but it does make consuming the event and checking for the message name a little cleaner – as you will see in the next section. Create a Global Message Broker In your WPF application, create an instance of this message broker class in the App class located in the App.xaml file. Create a public property in the App class and create a new instance of that class in the OnStartUp event procedure as shown in the following code: public partial class App : Application{  public PDSAMessageBroker MessageBroker { get; set; }   protected override void OnStartup(StartupEventArgs e)  {    base.OnStartup(e);     MessageBroker = new PDSAMessageBroker();  }} Sending and Receiving Messages Let’s assume you have a user control that you load into a control on your main window and you want to send a message from that user control to the main window. You might have the main window display a message box, or put a string into a status bar as shown in Figure 1. Figure 1: The main window can receive and send messages The first thing you do in the main window is to hook up an event procedure to the MessageReceived event of the global message broker. This is done in the constructor of the main window: public MainWindow(){  InitializeComponent();   (Application.Current as App).MessageBroker.     MessageReceived += new MessageReceivedEventHandler(       MessageBroker_MessageReceived);} One piece of code you might not be familiar with is accessing a property defined in the App class of your XAML application. Within the App.Xaml file is a class named App that inherits from the Application object. You access the global instance of this App class by using Application.Current. You cast Application.Current to ‘App’ prior to accessing any of the public properties or methods you defined in the App class. Thus, the code (Application.Current as App).MessageBroker, allows you to get at the MessageBroker property defined in the App class. In the MessageReceived event procedure in the main window (shown below) you can now check to see if the MessageName property of the PDSAMessageBrokerEventArgs is equal to “StatusBar” and if it is, then display the message body into the status bar text block control. void MessageBroker_MessageReceived(object sender,   PDSAMessageBrokerEventArgs e){  switch (e.MessageName)  {    case "StatusBar":      tbStatus.Text = e.Message.MessageBody.ToString();      break;  }} In the Page 1 user control’s Loaded event procedure you will send the message “StatusBar” through the global message broker to any listener using the following code: private void UserControl_Loaded(object sender,  RoutedEventArgs e){  // Send Status Message  (Application.Current as App).MessageBroker.    SendMessage(new PDSAMessageBrokerMessage("StatusBar",      "This is Page 1"));} Since the main window is listening for the message ‘StatusBar’, it will display the value “This is Page 1” in the status bar at the bottom of the main window. Sending a Message to a User Control The previous example sent a message from the user control to the main window. You can also send messages from the main window to any listener as well. Remember that the global message broker is really just a broadcaster to anyone who has hooked into the MessageReceived event. In the constructor of the user control named ucPage1 you can hook into the global message broker’s MessageReceived event. You can then listen for any messages that are sent to this control by using a similar switch-case structure like that in the main window. public ucPage1(){  InitializeComponent();   // Hook to the Global Message Broker  (Application.Current as App).MessageBroker.    MessageReceived += new MessageReceivedEventHandler(      MessageBroker_MessageReceived);} void MessageBroker_MessageReceived(object sender,  PDSAMessageBrokerEventArgs e){  // Look for messages intended for Page 1  switch (e.MessageName)  {    case "ForPage1":      MessageBox.Show(e.Message.MessageBody.ToString());      break;  }} Once the ucPage1 user control has been loaded into the main window you can then send a message using the following code: private void btnSendToPage1_Click(object sender,  RoutedEventArgs e){  PDSAMessageBrokerMessage arg =     new PDSAMessageBrokerMessage();   arg.MessageName = "ForPage1";  arg.MessageBody = "Message For Page 1";   // Send a message to Page 1  (Application.Current as App).MessageBroker.SendMessage(arg);} Since the MessageName matches what is in the ucPage1 MessageReceived event procedure, ucPage1 can do anything in response to that event. It is important to note that when the message gets sent it is sent to all MessageReceived event procedures, not just the one that is looking for a message called “ForPage1”. If the user control ucPage1 is not loaded and this message is broadcast, but no other code is listening for it, then it is simply ignored. Remove Event Handler In each class where you add an event handler to the MessageReceived event you need to make sure to remove those event handlers when you are done. Failure to do so can cause a strong reference to the class and thus not allow that object to be garbage collected. In each of your user control’s make sure in the Unloaded event to remove the event handler. private void UserControl_Unloaded(object sender, RoutedEventArgs e){  if (_MessageBroker != null)    _MessageBroker.MessageReceived -=         _MessageBroker_MessageReceived;} Problems with Message Brokering As with most “global” classes or classes that hook up events to other classes, garbage collection is something you need to consider. Just the simple act of hooking up an event procedure to a global event handler creates a reference between your user control and the message broker in the App class. This means that even when your user control is removed from your UI, the class will still be in memory because of the reference to the message broker. This can cause messages to still being handled even though the UI is not being displayed. It is up to you to make sure you remove those event handlers as discussed in the previous section. If you don’t, then the garbage collector cannot release those objects. Instead of using events to send messages from one object to another you might consider registering your objects with a central message broker. This message broker now becomes a collection class into which you pass an object and what messages that object wishes to receive. You do end up with the same problem however. You have to un-register your objects; otherwise they still stay in memory. To alleviate this problem you can look into using the WeakReference class as a method to store your objects so they can be garbage collected if need be. Discussing Weak References is beyond the scope of this post, but you can look this up on the web. Summary In this blog post you learned how to create a simple message broker system that will allow you to send messages from one object to another without having to reference objects directly. This does reduce the coupling between objects in your application. You do need to remember to get rid of any event handlers prior to your objects going out of scope or you run the risk of having memory leaks and events being called even though you can no longer access the object that is responding to that event. NOTE: You can download the sample code for this article by visiting my website at http://www.pdsa.com/downloads. Select “Tips & Tricks”, then select “A Communication System for XAML Applications” from the drop down list.

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• Security in Software

  The term security has many meanings based on the context and perspective in which it is used. Security from the perspective of software/system development is the continuous process of maintaining confidentiality, integrity, and availability of a system, sub-system, and system data. This definition at a very high level can be restated as the following: Computer security is a continuous process dealing with confidentiality, integrity, and availability on multiple layers of a system. Key Aspects of Software Security Integrity Confidentiality Availability Integrity within a system is the concept of ensuring only authorized users can only manipulate information through authorized methods and procedures. An example of this can be seen in a simple lead management application.  If the business decided to allow each sales member to only update their own leads in the system and sales managers can update all leads in the system then an integrity violation would occur if a sales member attempted to update someone else’s leads. An integrity violation occurs when a team member attempts to update someone else’s lead because it was not entered by the sales member.  This violates the business rule that leads can only be update by the originating sales member. Confidentiality within a system is the concept of preventing unauthorized access to specific information or tools.  In a perfect world the knowledge of the existence of confidential information/tools would be unknown to all those who do not have access. When this this concept is applied within the context of an application only the authorized information/tools will be available. If we look at the sales lead management system again, leads can only be updated by originating sales members. If we look at this rule then we can say that all sales leads are confidential between the system and the sales person who entered the lead in to the system. The other sales team members would not need to know about the leads let alone need to access it. Availability within a system is the concept of authorized users being able to access the system. A real world example can be seen again from the lead management system. If that system was hosted on a web server then IP restriction can be put in place to limit access to the system based on the requesting IP address. If in this example all of the sales members where accessing the system from the 192.168.1.23 IP address then removing access from all other IPs would be need to ensure that improper access to the system is prevented while approved users can access the system from an authorized location. In essence if the requesting user is not coming from an authorized IP address then the system will appear unavailable to them. This is one way of controlling where a system is accessed. Through the years several design principles have been identified as being beneficial when integrating security aspects into a system. These principles in various combinations allow for a system to achieve the previously defined aspects of security based on generic architectural models. Security Design Principles Least Privilege Fail-Safe Defaults Economy of Mechanism Complete Mediation Open Design Separation Privilege Least Common Mechanism Psychological Acceptability Defense in Depth Least Privilege Design PrincipleThe Least Privilege design principle requires a minimalistic approach to granting user access rights to specific information and tools. Additionally, access rights should be time based as to limit resources access bound to the time needed to complete necessary tasks. The implications of granting access beyond this scope will allow for unnecessary access and the potential for data to be updated out of the approved context. The assigning of access rights will limit system damaging attacks from users whether they are intentional or not. This principle attempts to limit data changes and prevents potential damage from occurring by accident or error by reducing the amount of potential interactions with a resource. Fail-Safe Defaults Design PrincipleThe Fail-Safe Defaults design principle pertains to allowing access to resources based on granted access over access exclusion. This principle is a methodology for allowing resources to be accessed only if explicit access is granted to a user. By default users do not have access to any resources until access has been granted. This approach prevents unauthorized users from gaining access to resource until access is given. Economy of Mechanism Design PrincipleThe Economy of mechanism design principle requires that systems should be designed as simple and small as possible. Design and implementation errors result in unauthorized access to resources that would not be noticed during normal use. Complete Mediation Design PrincipleThe Complete Mediation design principle states that every access to every resource must be validated for authorization. Open Design Design PrincipleThe Open Design Design Principle is a concept that the security of a system and its algorithms should not be dependent on secrecy of its design or implementation Separation Privilege Design PrincipleThe separation privilege design principle requires that all resource approved resource access attempts be granted based on more than a single condition. For example a user should be validated for active status and has access to the specific resource. Least Common Mechanism Design PrincipleThe Least Common Mechanism design principle declares that mechanisms used to access resources should not be shared. Psychological Acceptability Design PrincipleThe Psychological Acceptability design principle refers to security mechanisms not make resources more difficult to access than if the security mechanisms were not present Defense in Depth Design PrincipleThe Defense in Depth design principle is a concept of layering resource access authorization verification in a system reduces the chance of a successful attack. This layered approach to resource authorization requires unauthorized users to circumvent each authorization attempt to gain access to a resource. When designing a system that requires meeting a security quality attribute architects need consider the scope of security needs and the minimum required security qualities. Not every system will need to use all of the basic security design principles but will use one or more in combination based on a company’s and architect’s threshold for system security because the existence of security in an application adds an additional layer to the overall system and can affect performance. That is why the definition of minimum security acceptably is need when a system is design because this quality attributes needs to be factored in with the other system quality attributes so that the system in question adheres to all qualities based on the priorities of the qualities. Resources: Barnum, Sean. Gegick, Michael. (2005). Least Privilege. Retrieved on August 28, 2011 from https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/principles/351-BSI.html Saltzer, Jerry. (2011). BASIC PRINCIPLES OF INFORMATION PROTECTION. Retrieved on August 28, 2011 from  http://web.mit.edu/Saltzer/www/publications/protection/Basic.html Barnum, Sean. Gegick, Michael. (2005). Defense in Depth. Retrieved on August 28, 2011 from  https://buildsecurityin.us-cert.gov/bsi/articles/knowledge/principles/347-BSI.html Bertino, Elisa. (2005). Design Principles for Security. Retrieved on August 28, 2011 from  http://homes.cerias.purdue.edu/~bhargav/cs526/security-9.pdf

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• Apache Getting Bogged Down By Certain Script (Wp-Cron.php) - How To Kill Process Automatically

  - by user50037

  I have a server that is running a number of wordpress blogs, and a number of them have several hundred/thousand posts. Every couple of days, the server slows to a crawl due to a file being run on Wordpress called WP-cron.php. My entire apache process log turns into this : http:// imgur.com/A7K9k.png Times that by quite a bit. And server no go. Each process takes up about 1.1% of ram. And when we have 50 of them on the go. It gets insane. Not all of them are coming from the same blog, they are pretty widespread. In the Apache process page of WHM, they are usually ALL set to the status of "C", which means closing. But they can sit there until they crash the server, and they still hold the memory. Just google "wp-cron.php load" and you will find plenty of people with similar issues. In anycase, we have think it is down to users adding a tonne of dead "pinglists" to their wordpress installation. Which in turn wordpress loops through them endlessly. Problem number 1. Does anyone have any other suggestions about what would cause the Wordpress file wp-cron.php to loop endlessly. I still think it is down to pings, because all of the people we have contacted about their account load going sky high, have had massive ping lists. Problem number 2. Even if it is down to excessive pinglists in wordpress. We cannot be babying every single account on the server waiting for it to start spawning the wp-cron processes. It often happens overnight, and I start getting SMS alerts at 2am about the load. I have CSF installed, which apparently would have ended the processes if they ran over XXX time. But I have been told that it won't catch the processes because they end up in this state of "closing" (They show up as "C" on the Apache page of WHM). Apparently CSF will only kill processes that are "running" which C does not count. I have seen various other scripts such as : http://dltj.org/article/die-apache-die/ . I took a look at the stat of /proc. But I was boggled at which delimited part was the time running. And if there was any way I could connect it back to an actual Apache process, so that I could see what file was running (So only close connections connected to wp-cron.php, with a state of "C"). Overall I know Problem 2 glosses over the real reason. But I do put the whole thing to excessive pinglists in Wordpress. But I just cannot sit there and babysit every single installation 24/7. So I need a way to save the server when I am not available. Any help would be much appreciated.

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• How do you plan for starting a new web system?

  - by Kerry

  I've been creating more and more systems recently and I find more and more planning and preparation I do before starting the project. I determine what libraries or frameworks I will be using, what languages, the basic architecture of how the site will flow, etc. I've also heard of other design processes such as hanging styrofoam balls to show where classes are and how they relate, which is a process I've never heard of nor do I know how it works. Is there any software that helps with this process? Are there any guidelines or steps or do you have a recommended set of steps or guidelines that you follow when designing a new project?

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• launching a program from bash causes bash to go to new prompt

  - by Dan Dman

  When I run a program from the console, e.g. me@box:~$ firefox I expect the console to log error messages (I think this is std out or std err?) and other items from the program, firefox in this case. But today I notice that bash just opens the program and goes to a new prompt, e.g. me@box:~$ firefox me@box:~$ How do I launch a program from bash such that error messages will be written to the console? Why is it that some programs operate this way by default and others (firefox) do not?

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• Google’s April Fools Day Prank– Google Maps For Nintendo Entertainment System(NES)

  - by Gopinath

  Google is a funny organization and they celebrate most of events we love, in a geeky way. On the occasion of April Fool’s day 2012, Google released 8 bit Google Maps for Nintendo Entertainment System(NES). Here is the screen grab of Buckingham Palace, on 8 bit Google Maps. For those who are not aware of NES,  it is XBox of 1980’s.  NES is considered one of the most influential video game systems ever produced. Released in 1983, NES conquered millions of gamers heart and had a long lasting impact of 20 years. In the year of 2003, Nintendo finally stopped production of NES. Check out the embedded Google’s launch video of 8 Bit Google Maps for NES If you interested to take a tour the 8 bit Google Maps, go to Google Maps and click on the quest button available on right top corner. The guys at techi.com has a good collection of screen grabs taken from 8 Bit Google Maps, check it out here.

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• Shared Development Space

  - by PatrickWalker

  Currently the company I work in gives each developer their own development virtual machine. On this machine (Windows 7) they install the entire stack of the product (minus database) this stack is normally spread amongst multiple machines of differing OS (although moving towards windows 2008 and 2008r2) So when a developer has a new project they are likely to be updating only a small piece of their stack and as such the rest of it can become out of date with the latest production code. The isolation from others means some issues won't be found until the code goes into shared test environments/production. I'm suggesting a move from functional testing on these isolated machines to plugging machines into a shared environment. The goal being to move towards a deployment thats closer to production in mechanism and server type. Developers would still make code changes on their Win7 vm and run unit/component testing locally but for functionally testing they would leverage a shared enviornment. Does anyone else use a shared development environment like this? Are there many reasons against this sort of sandbox environment? The biggest drawback is a move away from only checking in code when you've done local functional testing to checking in after static testing. I'm hoping an intelligent git branching strategy can take care of this for us.

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• "Operation System not found" Dell XPS 15Z L511Z

  - by akikara

  Although title is the same problem is different. I've installed Ubuntu 14.04 Trusty on my HP EliteBook 6930p Notebook. And I was trying to create a bootable usb for my DELL XPS 15z. After successful creation of usb with usb-creator-gtk I plugged in bootable usb stick to DELL laptop. The error message was "Operation System not found". I tried several things but could not make it. When I check from working Ubuntu, I can see that usb is bootable and has files for installation.

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• Hyperlinked, externalized source code documentation

  - by Dave Jarvis

  Why do we still embed natural language descriptions of source code (i.e., the reason why a line of code was written) within the source code, rather than as a separate document? Given the expansive real-estate afforded to modern development environments (high-resolution monitors, dual-monitors, etc.), an IDE could provide semi-lock-step panels wherein source code is visually separated from -- but intrinsically linked to -- its corresponding comments. For example, developers could write source code comments in a hyper-linked markup language (linking to additional software requirements), which would simultaneously prevent documentation from cluttering the source code. What shortcomings would inhibit such a software development mechanism? A mock-up to help clarify the question: When the cursor is at a particular line in the source code (shown with a blue background, above), the documentation that corresponds to the line at the cursor is highlighted (i.e., distinguished from the other details). As noted in the question, the documentation would stay in lock-step with the source code as the cursor jumps through the source code. A hot-key could switch between "documentation mode" and "development mode". Potential advantages include: More source code and more documentation on the screen(s) at once Ability to edit documentation independently of source code (regardless of language?) Write documentation and source code in parallel without merge conflicts Real-time hyperlinked documentation with superior text formatting Quasi-real-time machine translation into different natural languages Every line of code can be clearly linked to a task, business requirement, etc. Documentation could automatically timestamp when each line of code was written (metrics) Dynamic inclusion of architecture diagrams, images to explain relations, etc. Single-source documentation (e.g., tag code snippets for user manual inclusion). Note: The documentation window can be collapsed Workflow for viewing or comparing source files would not be affected How the implementation happens is a detail; the documentation could be: kept at the end of the source file; split into two files by convention (filename.c, filename.c.doc); or fully database-driven By hyperlinked documentation, I mean linking to external sources (such as StackOverflow or Wikipedia) and internal documents (i.e., a wiki on a subdomain that could cross-reference business requirements documentation) and other source files (similar to JavaDocs). Related thread: What's with the aversion to documentation in the industry?

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• Yelp Like Adjective Rating System

  - by clifgray

  I am building a website that has users list their outdoor adventures (skydiving, surfing, base jumping, etc) and the other people can comment on them. I want to have a rating system like Yelp which has "Useful, Funny, or Cool" but with different adjectives. I have thought of a few such as Daring, Adventurous, and Unique but I wanted to get some feedback on what a few other good adjectives would be. Also does anyone have experience with other such systems or advice for better systems? Primarily I just want the user to have somewhat more descriptive voting options than u and down or 1 though 5.

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• FluentPath: a fluent wrapper around System.IO

  .NET is now more than eight years old, and some of its APIs got old with more grace than others. System.IO in particular has always been a little awkward. Its mostly static method calls (Path.*, Directory.*, etc.) and some stateful classes (DirectoryInfo, FileInfo). In these APIs, paths are plain strings. Since .NET v1, lots of good things happened to C#: lambda expressions, extension methods, optional parameters to name just a few. Outside of .NET, other interesting things happened as well. For...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• Does code-generation increase the code quality?

  - by platzhirsch

  Arguing for code-generation I am looking for some reasons, if howsoever, code generation increases the code quality, respectively is in favor for quality insurance. To clarify what I mean with code-generation I can talk only about a project of mine: We use XML files to describe different relationships, in fact our database schema. These XML files are used to generate our ORM framework and HTML forms which can be used to add, delete and modify entities. To my mind, it increases the quality, as the human error is reduced. If someone was implemented wrong, it is broken in the model. This is good, because the error might appear a lot faster, as more generated code is broken, too.

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• NTFS partitions hidden under EXT4 file system / partition...want to recover files from NTFS

  - by user7534

  I am new to ubuntu, but very impressed with the system. so one day i tried installing ubuntu 10.10 along with windows in dual boot first place it didnt get installed properly and during second attempt i could do it right but oh...i lost my windows 7 , here is my problem and what i have done till now. i have hdd installed with ubuntu same disk have windows partitions and i need to extract data from those ...very very important i tried to access the same from ubuntu ...can not access it, 3.reinstalled the windows 7 , hdd is not detected 4.during installation ubuntu gone , so reintalled scan in ubuntu says hdd is fine and DiskInternals linux reader actual show the NTFS partitions , recovery tool not able to get any data out. , please help i need data from these partitions...please I feel that i have put ext4 partition on ntfs filesystem...and now not able to access it

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• IBM System x3650 M2: Benchmark of Oracle's JDE 9.0 with Oracle VM

  - by didier.wojciechowski

  The IBM Oracle International Competency Center (ICC) in Denver, Colorado in a joint effort with the Oracle JD Edwards performance team was the first to execute a certified JD Edwards EnterpriseOne benchmark running on the new Intel® Xeon® processor 5500 series (Nehalem). This benchmark configuration included the IBM System x3650 M2, partitioned using Oracle Virtual Machine (VM), and Oracle's robust "Day in the Life" (DIL) test kit. In October, 2009 the benchmark scaled to 700 users with early code. In January 2010, with GA level code, the benchmark scaled successfully to 1000 users with sub-second response time.

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• NTFS partitions hidden under EXT4 file system / partion...want to recover files from NTFS

  - by user7534

  Hi all, I am new to ubuntu, but very impressed with the system. so one day i tried installing ubuntu 10.10 along with windows in dual boot first place it didnt get installed properly and during second attempt i could do it right but oh...i lost my windows 7 , here is my problem and what i have done till now. i have hdd installed with ubuntu same disk have windows partitions and i need to extract data from those ...very very important i tried to access the same from ubuntu ...can not access it, 3.reinstalled the windows 7 , hdd is not detected 4.during installation ubuntu gone , so reintalled scan in ubuntu says hdd is fine and DiskInternals linux reader actual show the NTFS partitions , recovery tool not able to get any data out. , please help i need data from these partitions...please I feel that i have put ext4 partition on ntfs filesystem...and now not able to access it

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• Why isn't software as reliable as a car?

  - by Alex Angas

  I had a user ask me this question. We know that cars break down, but that's because of something physical (unless software is involved!). I tried to answer that software is a much younger industry, but the user countered with "didn't the automobile industry become much more stable than and reliable with less people?". I also tried to answer that software is more complex, but the user countered that there are many thousands of parts that make up a car. People that design and build cars generally just know their component(s) very well, but they still all end up working together as an end result. So, why isn't software as reliable as a car?

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• Event system architecture for networking when performance is concerned

  - by Vandell

  How should I design a system for an action game (think in Golden Axe) where events can happen remotely? I'm using TCP for this because the client is in flash. There's so many options, I can make a binary protocol (I don't like this idea, I found it to be too hard to mantain) but I was also thinking that passing jsons through clients and server can be slow (Is that a exaggerated concern?). What about the internal architecture for the server? And for the client? I'm really lost, If it's a question that is too big, please indicate me some material so I can formulate a better question next time.

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• Using Lazy<T> and abstract wrapper class to lazy-load complex system parameters

  - by DigiMortal

  .NET Framework 4.0 introduced new class called Lazy<T> and I wrote blog post about it: .Net Framework 4.0: Using System.Lazy<T>. One thing is annoying for me – we have to keep lazy loaded value and its value loader as separate things. In this posting I will introduce you my Lazy<T> wrapper for complex to get system parameters that uses template method to keep lazy value loader in parameter class. Problem with original implementation Here’s the sample code that shows you how Lazy<T> is usually used. This is just sample code, don’t focus on the fact that this is dummy console application. class Program {     static void Main(string[] args)     {         var temperature = new Lazy<int>(LoadMinimalTemperature);           Console.WriteLine("Minimal room temperature: " + temperature.Value);         Console.ReadLine();     }       protected static int LoadMinimalTemperature()     {         var returnValue = 0;           // Do complex stuff here           return true;     } } The problem is that our class with many lazy loaded properties will grow messy if it has all value loading code inside it. This code may be complex for more than one parameter and in this case it is better to use separate class for this parameter. Defining base class for parameters As a first step I will define base class for all lazy-loaded parameters. This class is wrapper around Lazy<T> and it also offers one template method that parameter classes have to override to provide loaded data. public abstract class LazyParameter<T> {     private Lazy<T> _lazyParam;       public LazyParameter()     {         _lazyParam = new Lazy<T>(Load);     }       protected abstract T Load();       public T Value     {         get { return _lazyParam.Value; }     } } It is also possible to extend Lazy<T> but I don’t prefer to do it as Lazy<T> has six constructors we have to take care of. Also I don’t like to expose Lazy<T> public interface to users of my parameter classes. Creating parameter class Now it’s time to create our first parameter class. Notice how few stuff we have in this class besides overridden Load() method. public class MinimalRoomTemperature : LazyParameter<int> {     protected override int Load()     {         var returnValue = 0;           // Do complex stuff here           return returnValue;     } } Using parameter class is simple. Here’s my test code. class Program {     static void Main(string[] args)     {         var parameter = new MinimalRoomTemperature();         Console.WriteLine("Minimal room temperature: " + parameter.Value);         Console.ReadLine();     } } Conclusion Lazy<T> is useful class that you usually don’t want to use outside from API-s. I like this class but I don’t like when people are using this class directly in application code. In this posting I showed you how to use Lazy<T> with wrapper class to get complex parameter loading code out from classes that use this parameter. We ended up with generic base class for parameters that you can also use as base for other similar classes (you have to find better name to base class in this case).

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• Business/Development Liaison Wanting To Enhance Understanding In Programming

  - by James Alexander

  I lead software development for a team of of about 20 devs and we're primarily a .net/sql server shop. We've recently created a new role in our organization for a more business like role to assist in prioritization of development and this business liaison has asked me if there are any books or resources he could use to better understand software concepts in a meaningful way. Any suggestions or advice would be greatly appreciated.

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• Can a Guy with Embedded System Background go into Game Development

  - by NANDAGOPAL

  Well, I finished my Masters in Embedded Systems, and I am working in GUI development, and working with graphic tools and images and GUI's keep me glued to my seat more than working on code for MUP/MUC . And I want to give game development a Fair chance, try out developing a game from scratch using basic libraries then tryout the same in a free/open source game engine and there is a good chance I may fall in love with it, but it is poissible for a person with an Electrical and Electronics Bachelors and Embedded Systems Masters ( just a years experience in the field) go into game development and be successful in the profession. And I asked the same question @ stackoverflow.com (wrong place to ask ) http://stackoverflow.com/questions/13794822/can-a-guy-with-embedded-system-background-go-into-game-development/13794943#13794943 And I received good but a very generic answer. I would be happy to know the actual pro's and con's of a master's in embedded systems migrating to Game Dev

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• can a guy with embedded system background go into game development

  - by NANDAGOPAL

  Well, I finished my Masters in Embedded Systems, and I am working in GUI development, and working with graphic tools and images and GUI's keep me glued to my seat more than working on code for MUP/MUC . And I want to give game development a Fair chance, try out developing a game from scratch using basic libraries then tryout the same in a free/open source game engine and there is a good chance I may fall in love with it, but it is poissible for a person with an Electrical and Electronics Bachelors and Embedded Systems Masters ( just a years experience in the field) go into game development and be successful in the profession. And I asked the same question @ stackoverflow.com (wrong place to ask ) http://stackoverflow.com/questions/13794822/can-a-guy-with-embedded-system-background-go-into-game-development/13794943#13794943 And I received good but a very generic answer. I would be happy to know the actual pro's and con's of a master's in embedded systems migrating to Game Dev And I am extremely sorry for asking the same question for the third time but I really did not know that stackoverflow had so many sister sites, So a really big sorry, and an even bigger thank you!

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