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  • LINQ Query using Multiple From and Multiple Collections

    1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Text; 5:  6: namespace ConsoleApplication2 7: { 8: class Program 9: { 10: static void Main(string[] args) 11: { 12: var emps = GetEmployees(); 13: var deps = GetDepartments(); 14:  15: var results = from e in emps 16: from d in deps 17: where e.EmpNo >= 1 && d.DeptNo <= 30 18: select new { Emp = e, Dept = d }; 19: 20: foreach (var item in results) 21: { 22: Console.WriteLine("{0},{1},{2},{3}", item.Dept.DeptNo, item.Dept.DName, item.Emp.EmpNo, item.Emp.EmpName); 23: } 24: } 25:  26: private static List<Emp> GetEmployees() 27: { 28: return new List<Emp>() { 29: new Emp() { EmpNo = 1, EmpName = "Smith", DeptNo = 10 }, 30: new Emp() { EmpNo = 2, EmpName = "Narayan", DeptNo = 20 }, 31: new Emp() { EmpNo = 3, EmpName = "Rishi", DeptNo = 30 }, 32: new Emp() { EmpNo = 4, EmpName = "Guru", DeptNo = 10 }, 33: new Emp() { EmpNo = 5, EmpName = "Priya", DeptNo = 20 }, 34: new Emp() { EmpNo = 6, EmpName = "Riya", DeptNo = 10 } 35: }; 36: } 37:  38: private static List<Department> GetDepartments() 39: { 40: return new List<Department>() { 41: new Department() { DeptNo=10, DName="Accounts" }, 42: new Department() { DeptNo=20, DName="Finance" }, 43: new Department() { DeptNo=30, DName="Travel" } 44: }; 45: } 46: } 47:  48: class Emp 49: { 50: public int EmpNo { get; set; } 51: public string EmpName { get; set; } 52: public int DeptNo { get; set; } 53: } 54:  55: class Department 56: { 57: public int DeptNo { get; set; } 58: public String DName { get; set; } 59: } 60: } span.fullpost {display:none;}

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  • ActAs and OnBehalfOf support in WIF

    - by cibrax
    I discussed a time ago how WIF supported a new WS-Trust 1.4 element, “ActAs”, and how that element could be used for authentication delegation.  The thing is that there is another feature in WS-Trust 1.4 that also becomes handy for this kind of scenario, and I did not mention in that last post, “OnBehalfOf”. Shiung Yong wrote an excellent summary about the difference of these two new features in this forum thread. He basically commented the following, “An ActAs RST element indicates that the requestor wants a token that contains claims about two distinct entities: the requestor, and an external entity represented by the token in the ActAs element. An OnBehalfOf RST element indicates that the requestor wants a token that contains claims only about one entity: the external entity represented by the token in the OnBehalfOf element. In short, ActAs feature is typically used in scenarios that require composite delegation, where the final recipient of the issued token can inspect the entire delegation chain and see not just the client, but all intermediaries to perform access control, auditing and other related activities based on the whole identity delegation chain. The ActAs feature is commonly used in multi-tiered systems to authenticate and pass information about identities between the tiers without having to pass this information at the application/business logic layer. OnBehalfOf feature is used in scenarios where only the identity of the original client is important and is effectively the same as identity impersonation feature available in the Windows OS today. When the OnBehalfOf is used the final recipient of the issued token can only see claims about the original client, and the information about intermediaries is not preserved. One common pattern where OnBehalfOf feature is used is the proxy pattern where the client cannot access the STS directly but is instead communicating through a proxy gateway. The proxy gateway authenticates the caller and puts information about him into the OnBehalfOf element of the RST message that it then sends to the real STS for processing. The resulting token is going to contain only claims related to the client of the proxy, making the proxy completely transparent and not visible to the receiver of the issued token.” Going back to WIF, “ActAs” and “OnBehalfOf” are both supported as extensions methods in the WCF client channel. public static class ChannelFactoryOperations {   public static T CreateChannelActingAs<T>(this ChannelFactory<T> factory,     SecurityToken actAs);     public static T CreateChannelOnBehalfOf<T>(this ChannelFactory<T> factory,     SecurityToken onBehalfOf); } Both methods receive the security token with the identity of the original caller.

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  • What does it mean when ARP shows <incomplete> on eth1

    - by Geoff Dalgas
    We have been using HAProxy along with heartbeat from the Linux-HA project. We are using two linux instances to provide a failover. Each server has with their own public IP and a single IP which is shared between the two using a virtual interface (eth1:1) at IP: 69.59.196.211 The virtual interface (eth1:1) IP 69.59.196.211 is configured as the gateway for the windows servers behind them and we use ip_forwarding to route traffic. We are experiencing an occasional network outage on one of our windows servers behind our linux gateways. HAProxy will detect the server is offline which we can verify by remoting to the failed server and attempting to ping the gateway: Pinging 69.59.196.211 with 32 bytes of data: Reply from 69.59.196.220: Destination host unreachable. Running arp -a on this failed server shows that there is no entry for the gateway address (69.59.196.211): Interface: 69.59.196.220 --- 0xa Internet Address Physical Address Type 69.59.196.161 00-26-88-63-c7-80 dynamic 69.59.196.210 00-15-5d-0a-3e-0e dynamic 69.59.196.212 00-21-5e-4d-45-c9 dynamic 69.59.196.213 00-15-5d-00-b2-0d dynamic 69.59.196.215 00-21-5e-4d-61-1a dynamic 69.59.196.217 00-21-5e-4d-2c-e8 dynamic 69.59.196.219 00-21-5e-4d-38-e5 dynamic 69.59.196.221 00-15-5d-00-b2-0d dynamic 69.59.196.222 00-15-5d-0a-3e-09 dynamic 69.59.196.223 ff-ff-ff-ff-ff-ff static 224.0.0.22 01-00-5e-00-00-16 static 224.0.0.252 01-00-5e-00-00-fc static 225.0.0.1 01-00-5e-00-00-01 static On our linux gateway instances arp -a shows: peak-colo-196-220.peak.org (69.59.196.220) at <incomplete> on eth1 stackoverflow.com (69.59.196.212) at 00:21:5e:4d:45:c9 [ether] on eth1 peak-colo-196-215.peak.org (69.59.196.215) at 00:21:5e:4d:61:1a [ether] on eth1 peak-colo-196-219.peak.org (69.59.196.219) at 00:21:5e:4d:38:e5 [ether] on eth1 peak-colo-196-222.peak.org (69.59.196.222) at 00:15:5d:0a:3e:09 [ether] on eth1 peak-colo-196-209.peak.org (69.59.196.209) at 00:26:88:63:c7:80 [ether] on eth1 peak-colo-196-217.peak.org (69.59.196.217) at 00:21:5e:4d:2c:e8 [ether] on eth1 Why would arp occasionally set the entry for this failed server as <incomplete>? Should we be defining our arp entries statically? I've always left arp alone since it works 99% of the time, but in this one instance it appears to be failing. Are there any additional troubleshooting steps we can take help resolve this issue? THINGS WE HAVE TRIED I added a static arp entry for testing on one of the linux gateways which still didn't help. root@haproxy2:~# arp -a peak-colo-196-215.peak.org (69.59.196.215) at 00:21:5e:4d:61:1a [ether] on eth1 peak-colo-196-221.peak.org (69.59.196.221) at 00:15:5d:00:b2:0d [ether] on eth1 stackoverflow.com (69.59.196.212) at 00:21:5e:4d:45:c9 [ether] on eth1 peak-colo-196-219.peak.org (69.59.196.219) at 00:21:5e:4d:38:e5 [ether] on eth1 peak-colo-196-209.peak.org (69.59.196.209) at 00:26:88:63:c7:80 [ether] on eth1 peak-colo-196-217.peak.org (69.59.196.217) at 00:21:5e:4d:2c:e8 [ether] on eth1 peak-colo-196-220.peak.org (69.59.196.220) at 00:21:5e:4d:30:8d [ether] PERM on eth1 root@haproxy2:~# arp -i eth1 -s 69.59.196.220 00:21:5e:4d:30:8d root@haproxy2:~# ping 69.59.196.220 PING 69.59.196.220 (69.59.196.220) 56(84) bytes of data. --- 69.59.196.220 ping statistics --- 7 packets transmitted, 0 received, 100% packet loss, time 6006ms Rebooting the windows web server solves this issue temporarily with no other changes to the network but our experience shows this issue will come back. Swapping network cards and switches I noticed the link light on the port of the switch for the failed windows server was running at 100Mb instead of 1Gb on the failed interface. I moved the cable to several other open ports and the link indicated 100Mb for each port that I tried. I also swapped the cable with the same result. I tried changing the properties of the network card in windows and the server locked up and required a hard reset after clicking apply. This windows server has two physical network interfaces so I have swapped the cables and network settings on the two interfaces to see if the problem follows the interface. If the public interface goes down again we will know that it is not an issue with the network card. (We also tried another switch we have on hand, no change) Changing network hardware driver versions We've had the same problem with the latest Broadcom driver, as well as the built-in driver that ships in Windows Server 2008 R2. Replacing network cables As a last ditch effort we remembered another change that occurred was the replacement of all of the patch cords between our servers / switch. We had purchased two sets, one green of lengths 1ft - 3ft for the private interfaces and another set of red cables for the public interfaces. We swapped out all of the public interface patch cables with a different brand and ran our servers without issue for a full week ... aaaaaand then the problem recurred. Disable checksum offload, remove TProxy We also tried disabling TCP/IP checksum offload in the driver, no change. We're now pulling out TProxy and moving to a more traditional x-forwarded-for network arrangement without any fancy IP address rewriting. We'll see if that helps.

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  • RK4 Bouncing a Ball

    - by Jonathan Dickinson
    I am trying to wrap my head around RK4. I decided to do the most basic 'ball with gravity that bounces' simulation. I have implemented the following integrator given Glenn Fiedler's tutorial: /// <summary> /// Represents physics state. /// </summary> public struct State { // Also used internally as derivative. // S: Position // D: Velocity. /// <summary> /// Gets or sets the Position. /// </summary> public Vector2 X; // S: Position // D: Acceleration. /// <summary> /// Gets or sets the Velocity. /// </summary> public Vector2 V; } /// <summary> /// Calculates the force given the specified state. /// </summary> /// <param name="state">The state.</param> /// <param name="t">The time.</param> /// <param name="acceleration">The value that should be updated with the acceleration.</param> public delegate void EulerIntegrator(ref State state, float t, ref Vector2 acceleration); /// <summary> /// Represents the RK4 Integrator. /// </summary> public static class RK4 { private const float OneSixth = 1.0f / 6.0f; private static void Evaluate(EulerIntegrator integrator, ref State initial, float t, float dt, ref State derivative, ref State output) { var state = new State(); // These are a premature optimization. I like premature optimization. // So let's not concentrate on that. state.X.X = initial.X.X + derivative.X.X * dt; state.X.Y = initial.X.Y + derivative.X.Y * dt; state.V.X = initial.V.X + derivative.V.X * dt; state.V.Y = initial.V.Y + derivative.V.Y * dt; output = new State(); output.X.X = state.V.X; output.X.Y = state.V.Y; integrator(ref state, t + dt, ref output.V); } /// <summary> /// Performs RK4 integration over the specified state. /// </summary> /// <param name="eulerIntegrator">The euler integrator.</param> /// <param name="state">The state.</param> /// <param name="t">The t.</param> /// <param name="dt">The dt.</param> public static void Integrate(EulerIntegrator eulerIntegrator, ref State state, float t, float dt) { var a = new State(); var b = new State(); var c = new State(); var d = new State(); Evaluate(eulerIntegrator, ref state, t, 0.0f, ref a, ref a); Evaluate(eulerIntegrator, ref state, t + dt * 0.5f, dt * 0.5f, ref a, ref b); Evaluate(eulerIntegrator, ref state, t + dt * 0.5f, dt * 0.5f, ref b, ref c); Evaluate(eulerIntegrator, ref state, t + dt, dt, ref c, ref d); a.X.X = OneSixth * (a.X.X + 2.0f * (b.X.X + c.X.X) + d.X.X); a.X.Y = OneSixth * (a.X.Y + 2.0f * (b.X.Y + c.X.Y) + d.X.Y); a.V.X = OneSixth * (a.V.X + 2.0f * (b.V.X + c.V.X) + d.V.X); a.V.Y = OneSixth * (a.V.Y + 2.0f * (b.V.Y + c.V.Y) + d.V.Y); state.X.X = state.X.X + a.X.X * dt; state.X.Y = state.X.Y + a.X.Y * dt; state.V.X = state.V.X + a.V.X * dt; state.V.Y = state.V.Y + a.V.Y * dt; } } After reading over the tutorial I noticed a few things that just seemed 'out' to me. Notably how the entire simulation revolves around t at 0 and state at 0 - considering that we are working out a curve over the duration it seems logical that RK4 wouldn't be able to handle this simple scenario. Never-the-less I forged on and wrote a very simple Euler integrator: static void Integrator(ref State state, float t, ref Vector2 acceleration) { if (state.X.Y > 100 && state.V.Y > 0) { // Bounce vertically. acceleration.Y = -state.V.Y * t; } else { acceleration.Y = 9.8f; } } I then ran the code against a simple fixed-time step loop and this is what I got: 0.05 0.20 0.44 0.78 1.23 1.76 ... 74.53 78.40 82.37 86.44 90.60 94.86 99.23 103.05 105.45 106.94 107.86 108.42 108.76 108.96 109.08 109.15 109.19 109.21 109.23 109.23 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 109.24 ... As I said, I was expecting it to break - however I am unsure of how to fix it. I am currently looking into keeping the previous state and time, and working from that - although at the same time I assume that will defeat the purpose of RK4. How would I get this simulation to print the expected results?

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  • CDN CNAMEs not resolving to customer origin

    - by Donald Jenkins
    I have set up an Edgecast CDN to mirror all my static content. Because I use the root of my domain (donaldjenkins.com) to host my main site—using Google Analytics which sets cookies—I've stored the corresponding static files in a separate cookieless domain (donaldjenkins.info) which is used only for this purpose. I've set it up (using this guide for general guidance), with the following structure, based on a combination of customer origin and CDN origin to make the most of the chosen short domain name and provide meaningful URLs: http://donaldjenkins.info:80 is set as the customer origin for the content stored in the CDN at directory http://wac.62E0.edgecastcdn.net/8062E0/donaldjenkins.info; I've then set up various subdomains of a separate domain, the conveniently-named cdn.dj, as CDN-origin Edge CNAMEs for each of the corresponding static content types: js.cdn.dj points to the origin directory http://wac.62E0.edgecastcdn.net/0062E0/donaldjenkins.info/js; css.cdn.dj points to the origin directory http://wac.62E0.edgecastcdn.net/0062E0/donaldjenkins.info/css; images.cdn.dj points to the origin directory http://wac.62E0.edgecastcdn.net/0062E0/donaldjenkins.info/images and so on. This results in some pretty nice, short, clear URLs. The DNS zone file for cdn.dj (yes, it's a real domain name registered in Djibouti) is set properly: cdn.dj 43200 IN A 205.186.157.162 css.cdn.dj 43200 IN CNAME wac.62E0.edgecastcdn.net. images.cdn.dj 43200 IN CNAME wac.62E0.edgecastcdn.net. js.cdn.dj 43200 IN CNAME wac.62E0.edgecastcdn.net. The DNS resolves to the Edgecast URL: $ host js.cdn.dj js.cdn.dj is an alias for wac.62E0.edgecastcdn.net. wac.62E0.edgecastcdn.net is an alias for gs1.wac.edgecastcdn.net. gs1.wac.edgecastcdn.net has address 93.184.220.20 But whenever I try to fetch a file in any of the directories to which the CNAME assets map, I get a 404: $ curl http://js.cdn.dj/combined.js <?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>404 - Not Found</title> </head> <body> <h1>404 - Not Found</h1> </body> </html> despite the fact that the corresponding customer origin file exists: $ curl http://donaldjenkins.info/js/combined.js fetches the content of the combined.js file. Yet it's been more than enough time for the DNS to propagate since I set up the CDN. There's obviously some glaring mistake in the above-described setup, and I'm a bit of a novice with CDNs—but any suggestions would be gratefully received.

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  • Point of contact of 2 OBBs?

    - by Milo
    I'm working on the physics for my GTA2-like game so I can learn more about game physics. The collision detection and resolution are working great. I'm now just unsure how to compute the point of contact when I hit a wall. Here is my OBB class: public class OBB2D { private Vector2D projVec = new Vector2D(); private static Vector2D projAVec = new Vector2D(); private static Vector2D projBVec = new Vector2D(); private static Vector2D tempNormal = new Vector2D(); private Vector2D deltaVec = new Vector2D(); // Corners of the box, where 0 is the lower left. private Vector2D corner[] = new Vector2D[4]; private Vector2D center = new Vector2D(); private Vector2D extents = new Vector2D(); private RectF boundingRect = new RectF(); private float angle; //Two edges of the box extended away from corner[0]. private Vector2D axis[] = new Vector2D[2]; private double origin[] = new double[2]; public OBB2D(float centerx, float centery, float w, float h, float angle) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(centerx,centery,w,h,angle); } public OBB2D(float left, float top, float width, float height) { for(int i = 0; i < corner.length; ++i) { corner[i] = new Vector2D(); } for(int i = 0; i < axis.length; ++i) { axis[i] = new Vector2D(); } set(left + (width / 2), top + (height / 2),width,height,0.0f); } public void set(float centerx,float centery,float w, float h,float angle) { float vxx = (float)Math.cos(angle); float vxy = (float)Math.sin(angle); float vyx = (float)-Math.sin(angle); float vyy = (float)Math.cos(angle); vxx *= w / 2; vxy *= (w / 2); vyx *= (h / 2); vyy *= (h / 2); corner[0].x = centerx - vxx - vyx; corner[0].y = centery - vxy - vyy; corner[1].x = centerx + vxx - vyx; corner[1].y = centery + vxy - vyy; corner[2].x = centerx + vxx + vyx; corner[2].y = centery + vxy + vyy; corner[3].x = centerx - vxx + vyx; corner[3].y = centery - vxy + vyy; this.center.x = centerx; this.center.y = centery; this.angle = angle; computeAxes(); extents.x = w / 2; extents.y = h / 2; computeBoundingRect(); } //Updates the axes after the corners move. Assumes the //corners actually form a rectangle. private void computeAxes() { axis[0].x = corner[1].x - corner[0].x; axis[0].y = corner[1].y - corner[0].y; axis[1].x = corner[3].x - corner[0].x; axis[1].y = corner[3].y - corner[0].y; // Make the length of each axis 1/edge length so we know any // dot product must be less than 1 to fall within the edge. for (int a = 0; a < axis.length; ++a) { float l = axis[a].length(); float ll = l * l; axis[a].x = axis[a].x / ll; axis[a].y = axis[a].y / ll; origin[a] = corner[0].dot(axis[a]); } } public void computeBoundingRect() { boundingRect.left = JMath.min(JMath.min(corner[0].x, corner[3].x), JMath.min(corner[1].x, corner[2].x)); boundingRect.top = JMath.min(JMath.min(corner[0].y, corner[1].y),JMath.min(corner[2].y, corner[3].y)); boundingRect.right = JMath.max(JMath.max(corner[1].x, corner[2].x), JMath.max(corner[0].x, corner[3].x)); boundingRect.bottom = JMath.max(JMath.max(corner[2].y, corner[3].y),JMath.max(corner[0].y, corner[1].y)); } public void set(RectF rect) { set(rect.centerX(),rect.centerY(),rect.width(),rect.height(),0.0f); } // Returns true if other overlaps one dimension of this. private boolean overlaps1Way(OBB2D other) { for (int a = 0; a < axis.length; ++a) { double t = other.corner[0].dot(axis[a]); // Find the extent of box 2 on axis a double tMin = t; double tMax = t; for (int c = 1; c < corner.length; ++c) { t = other.corner[c].dot(axis[a]); if (t < tMin) { tMin = t; } else if (t > tMax) { tMax = t; } } // We have to subtract off the origin // See if [tMin, tMax] intersects [0, 1] if ((tMin > 1 + origin[a]) || (tMax < origin[a])) { // There was no intersection along this dimension; // the boxes cannot possibly overlap. return false; } } // There was no dimension along which there is no intersection. // Therefore the boxes overlap. return true; } public void moveTo(float centerx, float centery) { float cx,cy; cx = center.x; cy = center.y; deltaVec.x = centerx - cx; deltaVec.y = centery - cy; for (int c = 0; c < 4; ++c) { corner[c].x += deltaVec.x; corner[c].y += deltaVec.y; } boundingRect.left += deltaVec.x; boundingRect.top += deltaVec.y; boundingRect.right += deltaVec.x; boundingRect.bottom += deltaVec.y; this.center.x = centerx; this.center.y = centery; computeAxes(); } // Returns true if the intersection of the boxes is non-empty. public boolean overlaps(OBB2D other) { if(right() < other.left()) { return false; } if(bottom() < other.top()) { return false; } if(left() > other.right()) { return false; } if(top() > other.bottom()) { return false; } if(other.getAngle() == 0.0f && getAngle() == 0.0f) { return true; } return overlaps1Way(other) && other.overlaps1Way(this); } public Vector2D getCenter() { return center; } public float getWidth() { return extents.x * 2; } public float getHeight() { return extents.y * 2; } public void setAngle(float angle) { set(center.x,center.y,getWidth(),getHeight(),angle); } public float getAngle() { return angle; } public void setSize(float w,float h) { set(center.x,center.y,w,h,angle); } public float left() { return boundingRect.left; } public float right() { return boundingRect.right; } public float bottom() { return boundingRect.bottom; } public float top() { return boundingRect.top; } public RectF getBoundingRect() { return boundingRect; } public boolean overlaps(float left, float top, float right, float bottom) { if(right() < left) { return false; } if(bottom() < top) { return false; } if(left() > right) { return false; } if(top() > bottom) { return false; } return true; } public static float distance(float ax, float ay,float bx, float by) { if (ax < bx) return bx - ay; else return ax - by; } public Vector2D project(float ax, float ay) { projVec.x = Float.MAX_VALUE; projVec.y = Float.MIN_VALUE; for (int i = 0; i < corner.length; ++i) { float dot = Vector2D.dot(corner[i].x,corner[i].y,ax,ay); projVec.x = JMath.min(dot, projVec.x); projVec.y = JMath.max(dot, projVec.y); } return projVec; } public Vector2D getCorner(int c) { return corner[c]; } public int getNumCorners() { return corner.length; } public static float collisionResponse(OBB2D a, OBB2D b, Vector2D outNormal) { float depth = Float.MAX_VALUE; for (int i = 0; i < a.getNumCorners() + b.getNumCorners(); ++i) { Vector2D edgeA; Vector2D edgeB; if(i >= a.getNumCorners()) { edgeA = b.getCorner((i + b.getNumCorners() - 1) % b.getNumCorners()); edgeB = b.getCorner(i % b.getNumCorners()); } else { edgeA = a.getCorner((i + a.getNumCorners() - 1) % a.getNumCorners()); edgeB = a.getCorner(i % a.getNumCorners()); } tempNormal.x = edgeB.x -edgeA.x; tempNormal.y = edgeB.y - edgeA.y; tempNormal.normalize(); projAVec.equals(a.project(tempNormal.x,tempNormal.y)); projBVec.equals(b.project(tempNormal.x,tempNormal.y)); float distance = OBB2D.distance(projAVec.x, projAVec.y,projBVec.x,projBVec.y); if (distance > 0.0f) { return 0.0f; } else { float d = Math.abs(distance); if (d < depth) { depth = d; outNormal.equals(tempNormal); } } } float dx,dy; dx = b.getCenter().x - a.getCenter().x; dy = b.getCenter().y - a.getCenter().y; float dot = Vector2D.dot(dx,dy,outNormal.x,outNormal.y); if(dot > 0) { outNormal.x = -outNormal.x; outNormal.y = -outNormal.y; } return depth; } public Vector2D getMoveDeltaVec() { return deltaVec; } }; Thanks!

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  • Async CTP (C# 5): How to make WCF work with Async CTP

    - by javarg
    If you have recently downloaded the new Async CTP you will notice that WCF uses Async Pattern and Event based Async Pattern in order to expose asynchronous operations. In order to make your service compatible with the new Async/Await Pattern try using an extension method similar to the following: WCF Async/Await Method public static class ServiceExtensions {     public static Task<DateTime> GetDateTimeTaskAsync(this Service1Client client)     {         return Task.Factory.FromAsync<DateTime>(             client.BeginGetDateTime(null, null),             ar => client.EndGetDateTime(ar));     } } The previous code snippet adds an extension method to the GetDateTime method of the Service1Client WCF proxy. Then used it like this (remember to add the extension method’s namespace into scope in order to use it): Code Snippet var client = new Service1Client(); var dt = await client.GetDateTimeTaskAsync(); Replace the proxy’s type and operation name for the one you want to await.

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  • Nginx and PHP Fundamentals

    - by Elton Stoneman
    Originally posted on: http://geekswithblogs.net/EltonStoneman/archive/2013/08/01/nginx-and-php-fundamentals.aspxHot on the heels of my .NET caching course, I’ve had my first “fundamentals” course released on Pluralsight: Nginx and PHP Fundamentals. It’s a practical look at two of the biggest technologies on the web – Nginx, which is the fastest growing HTTP server around (currently hosting 100+ million sites), and PHP, which powers more websites than any other server-side framework (currently 240+ million sites). The two technologies work well together, both are open-source and cross-platform and both are lightweight and easy to get started with - you just need to download and unzip the runtimes, and with a text editor you can create and host dynamic websites. I’ve used PHP as a second (sometimes third) language since 2005 when I was brought cold into an established codebase to help improve performance, and Nginx to host tier 2 apps for the last couple of years. As with any training course, you learn new things as you produce it, and it was good to focus on a different stack from my commercial .NET world. In the course I start with a website in two parts – one which is just static content, and one which processes a user registration form using ASP.NET MVC, both running in IIS. Over four modules I migrate the app to Nginx and PHP: Hosting Static Content in Nginx – how to deploy and configure Nginx for a basic website; PHP Part 1: Basic Web Forms – installing PHP and an IDE, and building a simple form with server-side validation; PHP Part 2: Packages and Integration – using PECL and Composer for packages to connect to Azure, AWS, Mongo and reCAPTCHA; Hosting PHP in Nginx – configuring Nginx to host our PHP site. Along the way I run some performance stats with JMeter, and the headlines are that Nginx running on Linux outperforms IIS on Windows for static content,by 800 requests per second over 1000 concurrent requests; and Linux+Ngnix+PHP outperforms Windows+IIS+ASP.NET MVC by 700 request per second with the same load. Of course, the headline stats don’t tell the whole story, and when you add OpCode caching for PHP and the ASP.NET Output Cache, the results are very different. As Web architecture moves away from heavy server-side processing, to Single Page Apps with client-side frameworks like AngularJS and Knockout, I think there’s an increasing need for high-performance, low-cost server technologies, and the combination of Nginx and PHP makes a compelling case.

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  • ifup eth0 failed in Ubuntu 11.10 and Ubuntu 10.04.3

    - by Ajay
    ifup eth0 failed to bring up eth0 First, I have set static ip using the below commands: Commands: ifdown eth0 ifconfig eth0 X.X.X.X netmask 255.255.252.0 up route add default gw X.X.X.X I was successful in setting up static ip X.X.X.X and I could see the same in the output of command "ifconfig". Now I am trying to revert network back to dhcp using the below commands: Commands: ifdown eth0 ifup eth0 Output : RTNETLINK answers: File exists ssh stop/waiting ssh start/running, process 1524 ifup eth0, failed to bring back dhcp. Contents of /etc/network/interfaces root@bdhcp396:~# cat /etc/network/interfaces # The loopback network interface auto lo iface lo inet loopback # The primary network interface auto eth0 iface eth0 inet dhcp Is this a bug in Ubuntu 11.10/10.04.3? I see a similar bug raised - https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/876829

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  • Initial Review - Mastering Unreal Technology I: Introduction to Level Design with Unreal Engine 3

    - by Matt Christian
    Recently I purchased 3 large volumes on using the Unreal 3 Engine to create levels and custom games.  This past weekend I cracked the spine of the first and started reading.  Here are my early impressions (I'm ~250 pages into it, with appendices it's about 900). Pros Interestingly, the book starts with an overview of the Unreal engines leading up to Unreal 3 (including Gears of War) and follows with some discussion on planning a mod and what goes into the game development process.  This is nice for an intro to the book and is much preferred rather than a simple chapter detailing what is on the included CD, how to install and setup UnrealEd, etc...  While the chapter on Unreal history and planning can be considered 'fluff', it's much less 'fluffy' than most books provide. I need to mention one thing here that is pretty crucial in the way I'm going to continue reviewing this book.  Most technical books like this are used as a shelf reference; as a thick volume you use for looking up techniques every now and again.  Even so, I prefer reading from cover to cover, including chapters I may already be knowledgable on (I'm sure this is typical for most people).  If there was a chapter on installing UnrealEd (the previously mentioned 'fluff'), I would probably force myself to read it, even though I've installed the game and engine multiple times on different systems. Chapter 3 is where we really get to the introduction piece of UnrealEd, creating your first basic level.  This large chapter details creating two small rooms, adding static meshes, adding lighting, creating and adding particle emitters, creating a door that animates with Unreal Matinee and Kismet, static meshes with physics, and other little additions to make your level look less beginner.  This really is a chapter that overviews the entire rest of the book, as each chapter following details the creation and intermediate usages of Static Meshes, Materials, Lighting, etc... One other very nice part to this book is the way the tutorials are setup.  Each tutorial builds off the previous and all are step-by-step.  If you haven't completed one yet, you can find all the starting files on the CD that comes with the book. Cons While the description of the overview chapter (Chapter 3) is fresh in your mind, let me start the cons by saying this chapter is setup extremely confusing for the noob.  At one point, you end up creating a door mesh and setting it up as a InteropMesh so that it is ready to be animated, only to switch to particles and spend a good portion of time working on a different piece of the level.  Yes, this is actually how I develop my levels (jumping back and forth), though it's very odd for a book to jump out of sequence. The next item might be a positive or a negative depending on your skill level with UnrealEd.  Most of the introduction to the editor layout is found in one of the Appendices instead of before Chapter 3.  For new readers, this might lead to confusion as Appendix A would typically be read between Chapter 2 and 3.  However, this is a positive for those with some experience in UnrealEd as they don't have to force themselves through a 'learn every editor button' chapter.  I'm listing this in the Cons section as the book is 'Introduction to...' and is probably going to be directed toward a lot of very beginner developers. Finally, there's a lack of general description to a lot of the underlying engine and what each piece in UnrealEd is or does.  Sometimes you'll be performing Tutorial after Tutorial with barely a paragraph in between describing ANY of what you've just done.  Tutorial 1.1 Step 6 says to press Button X, so you do.  But why?  This is in part a problem with the structure of the tutorials rather than the content of the book.  Since the tutorials are so focused on a step-by-step (or procedural) description of a process, you learn the process and not why you're doing that.  For example, you might learn how to size a material to a surface, but will only learn what buttons to press and not what each one does. This becomes extremely apparent in the chapter on Static Meshes as most of the chapter is spent in 3D Studio Max.  Since there are books on 3DSM and modelling, the book really only tells you the steps and says to go grab a book on modelling if you're really interested in 3DSM.  Again, I've learned the process to develop my own meshes in 3DSM, but I don't know the why behind the steps. Conclusion So far the book is very good though I would have a hard time recommending it to a complete beginner.  I would suggest anyone looking at this book (obviously including the other 2, more advanced volumes) to pick up a copy of UDK or Unreal 3 (available online or via download services such as Steam) and watch some online tutorials and play with it first.  You'll find plenty of online videos available that were created by the authors and may suit as a better introduction to the editor.

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  • Easy way to update models in your ASP.NET MVC business layer

    - by rajbk
    Brad Wilson just mentioned there is a static class ModelCopier that has a static method CopyModel(object from, object to) in the MVC Futures library. It uses reflection to match properties with the same name and compatible types. In short, instead of manually copying over properties as shown here: public void Save(EmployeeViewModel employeeViewModel){ var employee = (from emp in dataContext.Employees where emp.EmployeeID == employeeViewModel.EmployeeID select emp).SingleOrDefault(); if (employee != null) { employee.Address = employeeViewModel.Address; employee.Salary = employeeViewModel.Salary; employee.Title = employeeViewModel.Title; } dataContext.SubmitChanges();} you can use the method like so: public void Save(EmployeeViewModel employeeViewModel){ var employee = (from emp in dataContext.Employees where emp.EmployeeID == employeeViewModel.EmployeeID select emp).SingleOrDefault(); if (employee != null) { ModelCopier.CopyModel(employeeViewModel, employee); } dataContext.SubmitChanges();} Beautiful, isn’t it?

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  • Detecting Idle Time with Global Mouse and Keyboard Hooks in WPF

    - by jdanforth
    Years and years ago I wrote this blog post about detecting if the user was idle or active at the keyboard (and mouse) using a global hook. Well that code was for .NET 2.0 and Windows Forms and for some reason I wanted to try the same in WPF and noticed that a few things around the keyboard and mouse hooks didn’t work as expected in the WPF environment. So I had to change a few things and here’s the code for it, working in .NET 4. I took the liberty and refactored a few things while at it and here’s the code now. I’m sure I will need it in the far future as well. using System; using System.Diagnostics; using System.Runtime.InteropServices; namespace Irm.Tim.Snapper.Util { public class ClientIdleHandler : IDisposable { public bool IsActive { get; set; } int _hHookKbd; int _hHookMouse; public delegate int HookProc(int nCode, IntPtr wParam, IntPtr lParam); public event HookProc MouseHookProcedure; public event HookProc KbdHookProcedure; //Use this function to install thread-specific hook. [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] public static extern int SetWindowsHookEx(int idHook, HookProc lpfn, IntPtr hInstance, int threadId); //Call this function to uninstall the hook. [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] public static extern bool UnhookWindowsHookEx(int idHook); //Use this function to pass the hook information to next hook procedure in chain. [DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)] public static extern int CallNextHookEx(int idHook, int nCode, IntPtr wParam, IntPtr lParam); //Use this hook to get the module handle, needed for WPF environment [DllImport("kernel32.dll", CharSet = CharSet.Auto)] public static extern IntPtr GetModuleHandle(string lpModuleName); public enum HookType : int { GlobalKeyboard = 13, GlobalMouse = 14 } public int MouseHookProc(int nCode, IntPtr wParam, IntPtr lParam) { //user is active, at least with the mouse IsActive = true; Debug.Print("Mouse active"); //just return the next hook return CallNextHookEx(_hHookMouse, nCode, wParam, lParam); } public int KbdHookProc(int nCode, IntPtr wParam, IntPtr lParam) { //user is active, at least with the keyboard IsActive = true; Debug.Print("Keyboard active"); //just return the next hook return CallNextHookEx(_hHookKbd, nCode, wParam, lParam); } public void Start() { using (var currentProcess = Process.GetCurrentProcess()) using (var mainModule = currentProcess.MainModule) { if (_hHookMouse == 0) { // Create an instance of HookProc. MouseHookProcedure = new HookProc(MouseHookProc); // Create an instance of HookProc. KbdHookProcedure = new HookProc(KbdHookProc); //register a global hook _hHookMouse = SetWindowsHookEx((int)HookType.GlobalMouse, MouseHookProcedure, GetModuleHandle(mainModule.ModuleName), 0); if (_hHookMouse == 0) { Close(); throw new ApplicationException("SetWindowsHookEx() failed for the mouse"); } } if (_hHookKbd == 0) { //register a global hook _hHookKbd = SetWindowsHookEx((int)HookType.GlobalKeyboard, KbdHookProcedure, GetModuleHandle(mainModule.ModuleName), 0); if (_hHookKbd == 0) { Close(); throw new ApplicationException("SetWindowsHookEx() failed for the keyboard"); } } } } public void Close() { if (_hHookMouse != 0) { bool ret = UnhookWindowsHookEx(_hHookMouse); if (ret == false) { throw new ApplicationException("UnhookWindowsHookEx() failed for the mouse"); } _hHookMouse = 0; } if (_hHookKbd != 0) { bool ret = UnhookWindowsHookEx(_hHookKbd); if (ret == false) { throw new ApplicationException("UnhookWindowsHookEx() failed for the keyboard"); } _hHookKbd = 0; } } #region IDisposable Members public void Dispose() { if (_hHookMouse != 0 || _hHookKbd != 0) Close(); } #endregion } } The way you use it is quite simple, for example in a WPF application with a simple Window and a TextBlock: <Window x:Class="WpfApplication2.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Grid> <TextBlock Name="IdleTextBox"/> </Grid> </Window> And in the code behind we wire up the ClientIdleHandler and a DispatcherTimer that ticks every second: public partial class MainWindow : Window { private DispatcherTimer _dispatcherTimer; private ClientIdleHandler _clientIdleHandler; public MainWindow() { InitializeComponent(); } private void Window_Loaded(object sender, RoutedEventArgs e) { //start client idle hook _clientIdleHandler = new ClientIdleHandler(); _clientIdleHandler.Start(); //start timer _dispatcherTimer = new DispatcherTimer(); _dispatcherTimer.Tick += TimerTick; _dispatcherTimer.Interval = new TimeSpan(0, 0, 0, 1); _dispatcherTimer.Start(); } private void TimerTick(object sender, EventArgs e) { if (_clientIdleHandler.IsActive) { IdleTextBox.Text = "Active"; //reset IsActive flag _clientIdleHandler.IsActive = false; } else IdleTextBox.Text = "Idle"; } } Remember to reset the ClientIdleHandle IsActive flag after a check.

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  • Chunking a List - .NET vs Python

    - by Abhijeet Patel
    Chunking a List As I mentioned last time, I'm knee deep in python these days. I come from a statically typed background so it's definitely a mental adjustment. List comprehensions is BIG in Python and having worked with a few of them I can see why. Let's say we need to chunk a list into sublists of a specified size. Here is how we'd do it in C#  static class Extensions   {       public static IEnumerable<List<T>> Chunk<T>(this List<T> l, int chunkSize)       {           if (chunkSize <0)           {               throw new ArgumentException("chunkSize cannot be negative", "chunkSize");           }           for (int i = 0; i < l.Count; i += chunkSize)           {               yield return new List<T>(l.Skip(i).Take(chunkSize));           }       }    }    static void Main(string[] args)  {           var l = new List<string> { "a", "b", "c", "d", "e", "f","g" };             foreach (var list in l.Chunk(7))           {               string str = list.Aggregate((s1, s2) => s1 + "," + s2);               Console.WriteLine(str);           }   }   A little wordy but still pretty concise thanks to LINQ.We skip the iteration number plus chunkSize elements and yield out a new List of chunkSize elements on each iteration. The python implementation is a bit more terse. def chunkIterable(iter, chunkSize):      '''Chunks an iterable         object into a list of the specified chunkSize     '''        assert hasattr(iter, "__iter__"), "iter is not an iterable"      for i in xrange(0, len(iter), chunkSize):          yield iter[i:i + chunkSize]    if __name__ == '__main__':      l = ['a', 'b', 'c', 'd', 'e', 'f']      generator = chunkIterable(l,2)      try:          while(1):              print generator.next()      except StopIteration:          pass   xrange generates elements in the specified range taking in a seed and returning a generator. which can be used in a for loop(much like using a C# iterator in a foreach loop) Since chunkIterable has a yield statement, it turns this method into a generator as well. iter[i:i + chunkSize] essentially slices the list based on the current iteration index and chunksize and creates a new list that we yield out to the caller one at a time. A generator much like an iterator is a state machine and each subsequent call to it remembers the state at which the last call left off and resumes execution from that point. The caveat to keep in mind is that since variables are not explicitly typed we need to ensure that the object passed in is iterable using hasattr(iter, "__iter__").This way we can perform chunking on any object which is an "iterable", very similar to accepting an IEnumerable in the .NET land

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  • Collision detection with curves

    - by paldepind
    I'm working on a 2D game in which I would like to do collision detection between a moving circle and some kind of static curves (maybe Bezier curves). Currently my game features only straight lines as the static geometry and I'm doing the collision detection by calculating the distance from the circle to the lines, and projecting the circle out of the line in case the distance is less than the circles radius. How can I do this kind of collision detection in a relative straightforward way? I know for instance that Box2D features collision detection with Bezier curves. I don't need a full featured collision detection mechanism, just something that can do what I've described.

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  • SharePoint 2010 Hosting :: How to Customize SharePoint 2010 Global Navigation

    - by mbridge
    Requirements - SharePoint Foundation or SharePoint Server 2010 site - SharePoint Designer 2010 Steps 1. The first step in my process was to download from codeplex a starter masterpage http://startermasterpages.codeplex.com/ . 2. Once you downloaded the starter master page, open up your SharePoint site in SharePoint Designer 2010 and on the left in the “Site Objects “ area click on the folder “All Files” and drill down to catalogs >> masterpages . Once you are in the Masterpage folder copy and paste the _starter.master into this folder. 3. The first step in the customization process is to create your custom style sheet. To create your custom style sheet, click on the “all Files” folder and click on “Style Library.” Right click in the style library section and choose Style sheet. Once the style sheet is created, rename it style.css. Now open the style sheet you created in SharePoint Designer. 4. In this next step you will copy and paste the SharePoint core styles for the global navigation into your custom style sheet. Copy and paste the css below into the style sheet and save file .s4-tn{ padding:0px; margin:0px; } .s4-tn ul.static{ white-space:nowrap; } .s4-tn li.static > .menu-item{ /* [ReplaceColor(themeColor:"Dark2")] */ color:#3b4f65; white-space:nowrap; border:1px solid transparent; padding:4px 10px; display:inline-block; height:15px; vertical-align:middle; } .s4-tn ul.dynamic{ /* [ReplaceColor(themeColor:"Light2")] */ background-color:white; /* [ReplaceColor(themeColor:"Dark2-Lighter")] */ border:1px solid #D9D9D9; } .s4-tn li.dynamic > .menu-item{ display:block; padding:3px 10px; white-space:nowrap; font-weight:normal; } .s4-tn li.dynamic > a:hover{ font-weight:normal; /* [ReplaceColor(themeColor:"Light2-Lighter")] */ background-color:#D9D9D9; } .s4-tn li.static > a:hover { /* [ReplaceColor(themeColor:"Accent1")] */ color:#44aff6; text-decoration:underline; } 5. Once you created the style sheet, go back to the masterpage folder and open the _starter.master file and in the Customization category click edit file. 6. Next, when the edit file opens make sure you view it in split view. Now you are going to search for the reference to our custom masterpage in the code. Make sure you are scrolled to the top in the code section and press “ctrl f” on the key board. This will pop up the find and replace tool. In the” find what field”, copy and paste and then click find next. 7. Now, in the code replace You have now referenced your custom style sheet in your masterpage. 8. The next step is to locate your Global Navigation control, make sure you are scrolled to the top in the code section and press “ctrl f” on the key board. This will pop up the find and replace tool. In the” find what field”, copy and paste ID="TopNavigationMenuV4” and then click find next. Once you find ID="TopNavigationMenuV4” , you should see the following block of code which is the global navigation control: ID="TopNavigationMenuV4" Runat="server" EnableViewState="false" DataSourceID="topSiteMap" AccessKey="" UseSimpleRendering="true" UseSeparateCss="false" Orientation="Horizontal" StaticDisplayLevels="1" MaximumDynamicDisplayLevels="1" SkipLinkText="" CssClass="s4-tn" 9. In the global navigation code above you should see CssClass="s4-tn" . As an additional step you can replace "s4-tn" your own custom name like CssClass="MyNav" . If you can the name of the CSS class make sure you update your custom style sheet with the new name, example below: .MyNav{ padding:0px; margin:0px; } .MyNav ul.static{ white-space:nowrap; } 10. At this point you are ready to brand your global navigation. The next step is to modify your style.css with your customizations to the default SharePoint styles. Have fun styling and make sure you save your work often. Hope it helps!!

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  • Multicast delegates in c#

    - by Jalpesh P. Vadgama
    In yesterday’s post We learn about Delegates and how we can use delegates in C#. In today’s blog post we are going to learn about Multicast delegates. What is Multicast Delegates? As we all know we can assign methods as object to delegate and later on we can call that method with the help delegates. We can also assign more then methods to delegates that is called Multicast delegates. It’s provide functionality to execute more then method at a time. It’s maintain delegates as invocation list (linked list). Let’s understands that via a example. We are going to use yesterday’s example and then we will extend that code multicast delegates. Following code I have written to demonstrate the multicast delegates. using System; namespace Delegates { class Program { public delegate void CalculateNumber(int a, int b); static void Main(string[] args) { int a = 5; int b = 5; CalculateNumber addNumber = new CalculateNumber(AddNumber); CalculateNumber multiplyNumber = new CalculateNumber(MultiplyNumber); CalculateNumber multiCast = (CalculateNumber)Delegate.Combine (addNumber, multiplyNumber); multiCast.Invoke(a,b); Console.ReadLine(); } public static void AddNumber(int a, int b) { Console.WriteLine("Adding Number"); Console.WriteLine(5 + 6); } public static void MultiplyNumber(int a, int b) { Console.WriteLine("Multiply Number"); Console.WriteLine(5 + 6); } } } As you can see in the above code I have created two method one for adding two numbers and another for multiply two number. After that I have created two same CalculateNumber delegates addNumber and multiplyNumber then I have create a multicast delegates multiCast with combining two delegates. Now I want to call this both method so I have used Invoke method to call this delegates. As now our code is let’s run the application. Following is a output as expected. As you can we can execute multiple methods with multicast delegates the only thing you need to take care is that we need to type for both delegates. That’s it. Hope you like it. Stay tuned for more.. Till then happy programming.

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  • A C# implementation of the CallStream pattern

    - by Bertrand Le Roy
    Dusan published this interesting post a couple of weeks ago about a novel JavaScript chaining pattern: http://dbj.org/dbj/?p=514 It’s similar to many existing patterns, but the syntax is extraordinarily terse and it provides a new form of friction-free, plugin-less extensibility mechanism. Here’s a JavaScript example from Dusan’s post: CallStream("#container") (find, "div") (attr, "A", 1) (css, "color", "#fff") (logger); The interesting thing here is that the functions that are being passed as the first argument are arbitrary, they don’t need to be declared as plug-ins. Compare that with a rough jQuery equivalent that could look something like this: $.fn.logger = function () { /* ... */ } $("selector") .find("div") .attr("A", 1) .css("color", "#fff") .logger(); There is also the “each” method in jQuery that achieves something similar, but its syntax is a little more verbose. Of course, that this pattern can be expressed so easily in JavaScript owes everything to the extraordinary way functions are treated in that language, something Douglas Crockford called “the very best part of JavaScript”. One of the first things I thought while reading Dusan’s post was how I could adapt that to C#. After all, with Lambdas and delegates, C# also has its first-class functions. And sure enough, it works really really well. After about ten minutes, I was able to write this: CallStreamFactory.CallStream (p => Console.WriteLine("Yay!")) (Dump, DateTime.Now) (DumpFooAndBar, new { Foo = 42, Bar = "the answer" }) (p => Console.ReadKey()); Where the Dump function is: public static void Dump(object options) { Console.WriteLine(options.ToString()); } And DumpFooAndBar is: public static void DumpFooAndBar(dynamic options) { Console.WriteLine("Foo is {0} and bar is {1}.", options.Foo, options.Bar); } So how does this work? Well, it really is very simple. And not. Let’s say it’s not a lot of code, but if you’re like me you might need an Advil after that. First, I defined the signature of the CallStream method as follows: public delegate CallStream CallStream (Action<object> action, object options = null); The delegate define a call stream as something that takes an action (a function of the options) and an optional options object and that returns a delegate of its own type. Tricky, but that actually works, a delegate can return its own type. Then I wrote an implementation of that delegate that calls the action and returns itself: public static CallStream CallStream (Action<object> action, object options = null) { action(options); return CallStream; } Pretty nice, eh? Well, yes and no. What we are doing here is to execute a sequence of actions using an interesting novel syntax. But for this to be actually useful, you’d need to build a more specialized call stream factory that comes with some sort of context (like Dusan did in JavaScript). For example, you could write the following alternate delegate signature that takes a string and returns itself: public delegate StringCallStream StringCallStream(string message); And then write the following call stream (notice the currying): public static StringCallStream CreateDumpCallStream(string dumpPath) { StringCallStream str = null; var dump = File.AppendText(dumpPath); dump.AutoFlush = true; str = s => { dump.WriteLine(s); return str; }; return str; } (I know, I’m not closing that stream; sure; bad, bad Bertrand) Finally, here’s how you use it: CallStreamFactory.CreateDumpCallStream(@".\dump.txt") ("Wow, this really works.") (DateTime.Now.ToLongTimeString()) ("And that is all."); Next step would be to combine this contextual implementation with the one that takes an action parameter and do some really fun stuff. I’m only scratching the surface here. This pattern could reveal itself to be nothing more than a gratuitous mind-bender or there could be applications that we hardly suspect at this point. In any case, it’s a fun new construct. Or is this nothing new? You tell me… Comments are open :)

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  • MSCC: Global Windows Azure Bootcamp

    Mauritius participated and contributed to the Global Windows Azure Bootcamp 2014 (GWAB). Again! And this time stronger than ever, and together with 137 other locations in 56 countries world-wide. We had 62 named registrations, 7 guest additions and approximately 10 offline participants prior to the event day. Most interestingly the organisation of the GWAB through the MSCC helped to increased the number of craftsmen. The Mauritius Software Craftsmanship Community has currently 138 registered members - in less than one year! Only with those numbers we can proudly say that all the preparations and hard work towards this event already paid off. Personally, I'm really grateful that we had this kind of response and the feedback from some attendees confirmed that the MSCC is on the right track here on Cyber Island Mauritius. Inspired and motivated by the success of this event, rest assured that there will be more public events like the GWAB. This time it took some time to reflect on our meetup, following my first impression right on spot: "Wow, what an experience to organise and participate in this global event. Overall, I've been very pleased with the preparations and the event itself. Surely, there have been some nicks that we have to address and to improve for future activities like this. Quite frankly, we are not professional event organisers (not yet) but we learned a lot over the past couple of days. A big Thank You to our event sponsors, namely Microsoft Indian Ocean Islands & French Pacific, Ceridian Mauritius and Emtel. Without them this event wouldn't have happened - Thank You! And to the cool team members of Microsoft Student Partners (MSPs). You geeks did a great job! Thanks!" So, how many attendees did we actually have? 61! - Awesome - 61 cloud computing instances to help on the research of diabetes. During Saturday afternoon there was even an online publication on L'Express: Les développeurs mauriciens se joignent au combat contre le diabète Reactions of other attendees Don't take my word for granted... Here are some impressions and feedback from our participants: "Awesome event, really appreciated the presentations :-)" -- Kevin on event comments "very interesting and enriching." -- Diana on event comments "#gwab #gwabmru 2014 great success. Looking forward for gwab 2015" -- Wasiim on Twitter "Was there till the end. Awesome Event. I'll surely join upcoming meetup sessions :)" -- Luchmun on event comments "#gwabmru was not that cool. left early" -- Mohammad on Twitter The overall feedback is positive but we are absolutely aware that there quite a number of problems we had to face. We are already looking into that and ideas / action plans on how we will be able to improve it for future events. The sessions We started the day with welcoming speeches by Thierry Coret, Sr. Marketing Manager of Microsoft Indian Ocean Islands & French Pacific and Vidia Mooneegan, Managing Director and Sr. Vice President of Ceridian Mauritius. The clear emphasis was on the endless possibilities of cloud computing and how it can enable any kind of sectors here in the country. Then it was about time to set up the cloud computing services in order to contribute each attendees cloud computing resources to the global research of diabetes, a step by step guide presented by Arnaud Meslier, Technical Evangelist at Microsoft. Given a rendering package and a configuration file it was very interesting to follow the single steps in Windows Azure. Also, during the day we were not sure whether the set up had been correctly, as Mauritius didn't show up on the results board - which should have been the case after approximately 20 to 30 minutes. Anyways, let the minions work... Next, Arnaud gave a brief overview of the variety of services Windows Azure has to offer. Whether you need a development environment for your websites or mobiles app, running a virtual machine with your existing applications or simply putting a SQL database online. No worries, Windows Azure has the right packages available and the online management portal is really easy t handle. After this, we got a little bit more business oriented while Wasiim Hosenbocus, employee at Ceridian, took the attendees through the inerts of a real-life application, and demoed a couple of the existing features. He did a great job by showing how the different services of Windows Azure can be created and pulled together. After the lunch break it is always tough to keep the audience awake... And it was my turn. I gave a brief overview on operating and managing a SQL database on Windows Azure. Well, there are actually two options available and depending on your individual requirements you should be aware of both. The simpler version is called SQL Database and while provisioning only takes a couple of seconds, you should take into consideration that SQL Database has a number of constraints, like limitations on the actual database size - up to 5 GB as web edition and up to 150 GB maximum as business edition -, among others. Next, it was Chervine Bhiwoo's session on Windows Azure Mobile Services. It was absolutely amazing to see that the mobiles services directly offers you various project templates, like Windows 8 Store App, Android app, iOS app, and even Xamarin cross-platform app development. So, within a couple of minutes you can have your first mobile app active and running on Windows Azure. Furthermore, Chervine showed the attendees that adding another user interface, like Web Sites running on ASP.NET MVC 4 only takes a couple of minutes, too. And last but not least, we rounded up the day with Windows Azure Websites and hosting of Virtual Machines presented by some members of the local Microsoft Students Partners programme. Surely, one of the big advantages using Windows Azure is the availability of pre-defined installation packages of known web applications, like WordPress, Joomla!, or Ghost. Compared to running your own web site with a traditional web hoster it is surely en par, and depending on your personal level of expertise, Windows Azure provides you more liberty in terms of configuration than maybe a shared hosting environment. Running a pre-defined web application is one thing but in case that you would like to have more control over your hosting environment it is highly advised to opt for a virtual machine. Provisioning of an Ubuntu 12.04 LTS system was very simple to do but it takes some more minutes than you might expect. So, please be patient and take your time while Windows Azure gets everything in place for you. Afterwards, you can use a SecureShell (ssh) client like Putty in case of a Linux-based machine, or Remote Desktop Services when operating a Windows Server system to log in into your virtual machine. At the end of the day we had a great Q&A session and we finalised the event with our raffle of goodies. Participation in the raffle was bound to submission of the session survey and most gratefully we had a give-away for everyone. What a nice coincidence to finish of the day. Note: All session slides (and demo codes) will be made available on the MSCC event page. Please, check the Files section over there. (Some) Visual impressions from the event Just to give you an idea about what has happened during the GWAB 2014 at Ebene... Speakers and Microsoft Student Partners are getting ready for the Global Windows Azure Bootcamp 2014 GWAB 2014 attendees are fully integrated into the hands-on-labs and setting up their individuals cloud computing services 60 attendees at the GWAB 2014. Despite some technical difficulties we had a great time running the event GWAB 2014: Using the lunch break for networking and exchange of ideas - Great conversations and topics amongst attendees There are more pictures on the original event page: Questions & Answers Following are a couple of questions which have been asked and didn't get an answer during the event: Q: Is it possible to upload static pages via FTP? A: Yes, you can. Have a look at the right side column on the dashboard of your website. There you'll find information about the FTP and SFTP host names. You can use any FTP client, like ie. FileZilla to log in. FTP also gives you access to your log files. Q: What are the size limitations on SQL Database? A: 5 GB on the Web Edition, and 150 GB on the business edition. A maximum 150 databases (inclusing 'master') per SQL Database server. More details here: General Guidelines and Limitations (Azure SQL Database) Q: What's the maximum size of a SQL Server running in a Virtual Machine? A: The maximum Windows Azure VM has currently 8 CPU cores, 14 or 56 GB of RAM and 16x 1 TB hard drives. More details here: Virtual Machine and Cloud Service Sizes for Azure Q: How can we register for Windows Azure? A: Mauritius is currently not listed for phone verification. Please get in touch with Arnaud Meslier at Microsoft IOI & FP Q: Can I use my own domain name for Windows Azure websites? A: Yes, you can. But this might require to upscale your account to Standard. In case that I missed a question and answer, please use the comment section at the end of the article. Thanks! Final results Every participant was instructed during the hands-on-lab session on how to set up a cloud computing service in their account. Of course, I won't keep the results from you... Global Azure Lab GWAB 2014: Our cloud computing contribution to the research of diabetes And I would say Mauritius did a good job! Upcoming Events What are the upcoming events here in Mauritius? So far, we have the following ones (incomplete list as usual) in chronological order: Launch of Microsoft SQL Server 2014 (15.4.2014) Corsair Hackers Reboot (19.4.2014) WebCup (TBA ~ June 2014) Developers Conference (TBA ~ July 2014) Linuxfest 2014 (TBA ~ November 2014) Hopefully, there will be more announcements during the next couple of weeks and months. If you know about any other event, like a bootcamp, a code challenge or hackathon here in Mauritius, please drop me a note in the comment section below this article. Thanks! Networking and job/project opportunities Despite having technical presentations on Windows Azure an event like this always offers a great bunch of possibilities and opportunities to get in touch with new people in IT, have an exchange of experience with other like-minded people. As I already wrote about Communities - The importance of exchange and discussion - I had a great conversation with representatives of the University des Mascareignes which are currently embracing cloud infrastructure and cloud computing for their various campuses in the Indian Ocean. As for the MSCC it would be a great experience to stay in touch with them, and to work on upcoming, common activities. Furthermore, I had a very good conversation with Thierry and Ludovic of Microsoft IOI & FP on the necessity of user groups and IT communities here on the island. It's great to see that the MSCC is currently on a run and that local companies are sharing our thoughts on promoting IT careers and exchange of IT knowledge in such an open way. I'm also looking forward to be able to participate and to contribute on more events in the near future. My resume of the day We learned a lot today and there is always room for improvement! It was an awesome event and quite frankly it was a pleasure to spend the day with so many enthuastic IT people in the same room. It was a great experience to organise such event locally and participate on a global scale to support the GlyQ-IQ Technology in their research on diabetes. I was so pleased to see the involvement of new MSCC members in taking the opportunity to share and learn about the power of cloud computing. The Mauritius Software Craftsmanship Community is on the right way and this year's bootcamp on Windows Azure only marked the beginning of our journey. Thank you to our sponsors and my kudos to the MSPs! Update: Media coverage The event has been reported in local media, too. Following are some resources: Orange - Local - Business: Le cloud, pour des recherches approfondies sur le diabète Maurice Info.mu: Le cloud, pour des recherches approfondies sur le diabète Le Quotidien Pg 2: Global Windows Azure Bootcamp 2014 - Le cloud pour des recherches approfondies sur le diabète The Observer Pg 12: Le cloud, pour des recherches approfondies sur le diabète

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  • Best way to throw exception and avoid code duplication

    - by JF Dion
    I am currently writing code and want to make sure all the params that get passed to a function/method are valid. Since I am writing in PHP I don't have access to all the facilities of other languages like C, C++ or Java to check for parameters values and types public function inscriptionExists($sectionId, $userId) // PHP vs. public boolean inscriptionExists(int sectionId, int userId) // Java So I have to rely on exceptions if I want to make sure that my params are both integers. Since I have a lot of places where I need to check for param validity, what would be the best way to create a validation/exception machine and avoid code duplication? I was thinking on a static factory (since I don't want to pass it to all of my classes) with a signature like: public static function factory ($value, $valueType, $exceptionType = 'InvalidArgumentException'); Which would then call the right sub process to validate based on the type. Am I on the right way, or am I going completely off the road and overthinking my problem?

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  • Advanced donut caching: using dynamically loaded controls

    - by DigiMortal
    Yesterday I solved one caching problem with local community portal. I enabled output cache on SharePoint Server 2007 to make site faster. Although caching works fine I needed to do some additional work because there are some controls that show different content to different users. In this example I will show you how to use “donut caching” with user controls – powerful way to drive some content around cache. About donut caching Donut caching means that although you are caching your content you have some holes in it so you can still affect the output that goes to user. By example you can cache front page on your site and still show welcome message that contains correct user name. To get better idea about donut caching I suggest you to read ScottGu posting Tip/Trick: Implement "Donut Caching" with the ASP.NET 2.0 Output Cache Substitution Feature. Basically donut caching uses ASP.NET substitution control. In output this control is replaced by string you return from static method bound to substitution control. Again, take a look at ScottGu blog posting I referred above. Problem If you look at Scott’s example it is pretty plain and easy by its output. All it does is it writes out current user name as string. Here are examples of my login area for anonymous and authenticated users:    It is clear that outputting mark-up for these views as string is pretty lame to implement in code at string level. Every little change in design will end up with new version of controls library because some parts of design “live” there. Solution: using user controls I worked out easy solution to my problem. I used cache substitution and user controls together. I have three user controls: LogInControl – this is the proxy control that checks which “real” control to load. AnonymousLogInControl – template and logic for anonymous users login area. AuthenticatedLogInControl – template and logic for authenticated users login area. This is the control we render for each user separately because it contains user name and user profile fill percent. Anonymous control is not very interesting because it is only about keeping mark-up in separate file. Interesting parts are LogInControl and AuthenticatedLogInControl. Creating proxy control The first thing was to create control that has substitution area where “real” control is loaded. This proxy control should also be available to decide which control to load. The definition of control is very primitive. <%@ Control EnableViewState="false" Inherits="MyPortal.Profiles.LogInControl" %> <asp:Substitution runat="server" MethodName="ShowLogInBox" /> But code is a little bit tricky. Based on current user instance we decide which login control to load. Then we create page instance and load our control through it. When control is loaded we will call DataBind() method. In this method we evaluate all fields in loaded control (it was best choice as Load and other events will not be fired). Take a look at the code. public static string ShowLogInBox(HttpContext context) {     var user = SPContext.Current.Web.CurrentUser;     string controlName;       if (user != null)         controlName = "AuthenticatedLogInControl.ascx";     else         controlName = "AnonymousLogInControl.ascx";       var path = "~/_controltemplates/" + controlName;     var output = new StringBuilder(10000);       using(var page = new Page())     using(var ctl = page.LoadControl(path))     using(var writer = new StringWriter(output))     using(var htmlWriter = new HtmlTextWriter(writer))     {         ctl.DataBind();         ctl.RenderControl(htmlWriter);     }     return output.ToString(); } When control is bound to data we ask to render it its contents to StringBuilder. Now we have the output of control as string and we can return it from our method. Of course, notice how correct I am with resources disposing. :) The method that returns contents for substitution control is static method that has no connection with control instance because hen page is read from cache there are no instances of controls available. Conclusion As you saw it was not very hard to use donut caching with user controls. Instead of writing mark-up of controls to static method that is bound to substitution control we can still use our user controls.

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  • Continue with out a default route?

    - by user2009
    I am doing a complete unattended install of Ubuntu 12.04. I am doing static network configuration. Here is content for Static network configuration from the preseed file. d-i netcfg/disable_dhcp boolean true d-i netcfg/no_default_route boolean true d-i netcfg/get_nameservers string 192.168.1.254 d-i netcfg/get_ipaddress string 192.168.1.13 d-i netcfg/get_netmask string 255.255.255.0 d-i netcfg/get_gateway string 192.168.1.1 d-i netcfg/confirm_static boolean true Still is asking "Continue without a default route?". I have to say , then only installed is going ahead. Am passing preseed file via network (preseed/url). How to avoid this manual intervention? Does the order of netcfg statements matter?

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  • Do Not Optimize Without Measuring

    - by Alois Kraus
    Recently I had to do some performance work which included reading a lot of code. It is fascinating with what ideas people come up to solve a problem. Especially when there is no problem. When you look at other peoples code you will not be able to tell if it is well performing or not by reading it. You need to execute it with some sort of tracing or even better under a profiler. The first rule of the performance club is not to think and then to optimize but to measure, think and then optimize. The second rule is to do this do this in a loop to prevent slipping in bad things for too long into your code base. If you skip for some reason the measure step and optimize directly it is like changing the wave function in quantum mechanics. This has no observable effect in our world since it does represent only a probability distribution of all possible values. In quantum mechanics you need to let the wave function collapse to a single value. A collapsed wave function has therefore not many but one distinct value. This is what we physicists call a measurement. If you optimize your application without measuring it you are just changing the probability distribution of your potential performance values. Which performance your application actually has is still unknown. You only know that it will be within a specific range with a certain probability. As usual there are unlikely values within your distribution like a startup time of 20 minutes which should only happen once in 100 000 years. 100 000 years are a very short time when the first customer tries your heavily distributed networking application to run over a slow WIFI network… What is the point of this? Every programmer/architect has a mental performance model in his head. A model has always a set of explicit preconditions and a lot more implicit assumptions baked into it. When the model is good it will help you to think of good designs but it can also be the source of problems. In real world systems not all assumptions of your performance model (implicit or explicit) hold true any longer. The only way to connect your performance model and the real world is to measure it. In the WIFI example the model did assume a low latency high bandwidth LAN connection. If this assumption becomes wrong the system did have a drastic change in startup time. Lets look at a example. Lets assume we want to cache some expensive UI resource like fonts objects. For this undertaking we do create a Cache class with the UI themes we want to support. Since Fonts are expensive objects we do create it on demand the first time the theme is requested. A simple example of a Theme cache might look like this: using System; using System.Collections.Generic; using System.Drawing; struct Theme { public Color Color; public Font Font; } static class ThemeCache { static Dictionary<string, Theme> _Cache = new Dictionary<string, Theme> { {"Default", new Theme { Color = Color.AliceBlue }}, {"Theme12", new Theme { Color = Color.Aqua }}, }; public static Theme Get(string theme) { Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } return cached; } } class Program { static void Main(string[] args) { Theme item = ThemeCache.Get("Theme12"); item = ThemeCache.Get("Theme12"); } } This cache does create font objects only once since on first retrieve of the Theme object the font is added to the Theme object. When we let the application run it should print “Creating new font” only once. Right? Wrong! The vigilant readers have spotted the issue already. The creator of this cache class wanted to get maximum performance. So he decided that the Theme object should be a value type (struct) to not put too much pressure on the garbage collector. The code Theme cached = _Cache[theme]; if (cached.Font == null) { Console.WriteLine("Creating new font"); cached.Font = new Font("Arial", 8); } does work with a copy of the value stored in the dictionary. This means we do mutate a copy of the Theme object and return it to our caller. But the original Theme object in the dictionary will have always null for the Font field! The solution is to change the declaration of struct Theme to class Theme or to update the theme object in the dictionary. Our cache as it is currently is actually a non caching cache. The funny thing was that I found out with a profiler by looking at which objects where finalized. I found way too many font objects to be finalized. After a bit debugging I found the allocation source for Font objects was this cache. Since this cache was there for years it means that the cache was never needed since I found no perf issue due to the creation of font objects. the cache was never profiled if it did bring any performance gain. to make the cache beneficial it needs to be accessed much more often. That was the story of the non caching cache. Next time I will write something something about measuring.

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  • Entity Framework Code First: Get Entities From Local Cache or the Database

    - by Ricardo Peres
    Entity Framework Code First makes it very easy to access local (first level) cache: you just access the DbSet<T>.Local property. This way, no query is sent to the database, only performed in already loaded entities. If you want to first search local cache, then the database, if no entries are found, you can use this extension method: 1: public static class DbContextExtensions 2: { 3: public static IQueryable<T> LocalOrDatabase<T>(this DbContext context, Expression<Func<T, Boolean>> expression) where T : class 4: { 5: IEnumerable<T> localResults = context.Set<T>().Local.Where(expression.Compile()); 6:  7: if (localResults.Any() == true) 8: { 9: return (localResults.AsQueryable()); 10: } 11:  12: IQueryable<T> databaseResults = context.Set<T>().Where(expression); 13:  14: return (databaseResults); 15: } 16: }

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  • Website hosted at home pingable from outside, but not browseable from outside [closed]

    - by Richard DesLonde
    I have a simple setup. Server at home has local I.P. 192.168.1.3 IIS is running on the server and the website is up. Windows firewall on the server has an exception rule for port 80 TCP Router has static I.P. XX.XXX.XX.XXX Router is forwarding TCP port 80 to 192.168.1.3 My domain registrar is my DNS host and is pointing to the static I.P. XX.XXX.XX.XXX of the router Here's what I can and can't do. I can browse the website from within my home network either by I.P. or domain name. I can ping the domain and the I.P. from outside the network (from a computer at work). I can't browse the website either by domain name or by I.P. Wierd. Why I can't browse my website?

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  • Gateway IP Returns to Zero

    - by Robert Smith
    When you set a static IP under Ubuntu 12.04.1, you must supply the desired machine IP and the gateway IP, all using the Network Manager. When I first entered them and rebooted, everything worked great. On the second boot, however, Firefox could find no Web page. Upon checking, I discovered that the gateway IP had returned to zero. Now, no matter how often I resupply it, it returns to zero immediately after NM "saves" it: that is, appears as zero when redisplayed. The only way I can get to the Internet is to restore DHCP operation. I need to use static IP for access to my home network. Would appreciate any suggestion. --Robert Smith

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