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• DTracing TCP congestion control

  - by user12820842

  In a previous post, I showed how we can use DTrace to probe TCP receive and send window events. TCP receive and send windows are in effect both about flow-controlling how much data can be received - the receive window reflects how much data the local TCP is prepared to receive, while the send window simply reflects the size of the receive window of the peer TCP. Both then represent flow control as imposed by the receiver. However, consider that without the sender imposing flow control, and a slow link to a peer, TCP will simply fill up it's window with sent segments. Dealing with multiple TCP implementations filling their peer TCP's receive windows in this manner, busy intermediate routers may drop some of these segments, leading to timeout and retransmission, which may again lead to drops. This is termed congestion, and TCP has multiple congestion control strategies. We can see that in this example, we need to have some way of adjusting how much data we send depending on how quickly we receive acknowledgement - if we get ACKs quickly, we can safely send more segments, but if acknowledgements come slowly, we should proceed with more caution. More generally, we need to implement flow control on the send side also. Slow Start and Congestion Avoidance From RFC2581, let's examine the relevant variables: "The congestion window (cwnd) is a sender-side limit on the amount of data the sender can transmit into the network before receiving an acknowledgment (ACK). Another state variable, the slow start threshold (ssthresh), is used to determine whether the slow start or congestion avoidance algorithm is used to control data transmission" Slow start is used to probe the network's ability to handle transmission bursts both when a connection is first created and when retransmission timers fire. The latter case is important, as the fact that we have effectively lost TCP data acts as a motivator for re-probing how much data the network can handle from the sending TCP. The congestion window (cwnd) is initialized to a relatively small value, generally a low multiple of the sending maximum segment size. When slow start kicks in, we will only send that number of bytes before waiting for acknowledgement. When acknowledgements are received, the congestion window is increased in size until cwnd reaches the slow start threshold ssthresh value. For most congestion control algorithms the window increases exponentially under slow start, assuming we receive acknowledgements. We send 1 segment, receive an ACK, increase the cwnd by 1 MSS to 2*MSS, send 2 segments, receive 2 ACKs, increase the cwnd by 2*MSS to 4*MSS, send 4 segments etc. When the congestion window exceeds the slow start threshold, congestion avoidance is used instead of slow start. During congestion avoidance, the congestion window is generally updated by one MSS for each round-trip-time as opposed to each ACK, and so cwnd growth is linear instead of exponential (we may receive multiple ACKs within a single RTT). This continues until congestion is detected. If a retransmit timer fires, congestion is assumed and the ssthresh value is reset. It is reset to a fraction of the number of bytes outstanding (unacknowledged) in the network. At the same time the congestion window is reset to a single max segment size. Thus, we initiate slow start until we start receiving acknowledgements again, at which point we can eventually flip over to congestion avoidance when cwnd ssthresh. Congestion control algorithms differ most in how they handle the other indication of congestion - duplicate ACKs. A duplicate ACK is a strong indication that data has been lost, since they often come from a receiver explicitly asking for a retransmission. In some cases, a duplicate ACK may be generated at the receiver as a result of packets arriving out-of-order, so it is sensible to wait for multiple duplicate ACKs before assuming packet loss rather than out-of-order delivery. This is termed fast retransmit (i.e. retransmit without waiting for the retransmission timer to expire). Note that on Oracle Solaris 11, the congestion control method used can be customized. See here for more details. In general, 3 or more duplicate ACKs indicate packet loss and should trigger fast retransmit . It's best not to revert to slow start in this case, as the fact that the receiver knew it was missing data suggests it has received data with a higher sequence number, so we know traffic is still flowing. Falling back to slow start would be excessive therefore, so fast recovery is used instead. Observing slow start and congestion avoidance The following script counts TCP segments sent when under slow start (cwnd ssthresh). #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::connect-request / start[args[1]-cs_cid] == 0/ { start[args[1]-cs_cid] = 1; } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd tcps_cwnd_ssthresh / { @c["Slow start", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / start[args[1]-cs_cid] == 1 && args[3]-tcps_cwnd args[3]-tcps_cwnd_ssthresh / { @c["Congestion avoidance", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } As we can see the script only works on connections initiated since it is started (using the start[] associative array with the connection ID as index to set whether it's a new connection (start[cid] = 1). From there we simply differentiate send events where cwnd ssthresh (congestion avoidance). Here's the output taken when I accessed a YouTube video (where rport is 80) and from an FTP session where I put a large file onto a remote system. # dtrace -s tcp_slow_start.d ^C ALGORITHM RADDR RPORT #SEG Slow start 10.153.125.222 20 6 Slow start 138.3.237.7 80 14 Slow start 10.153.125.222 21 18 Congestion avoidance 10.153.125.222 20 1164 We see that in the case of the YouTube video, slow start was exclusively used. Most of the segments we sent in that case were likely ACKs. Compare this case - where 14 segments were sent using slow start - to the FTP case, where only 6 segments were sent before we switched to congestion avoidance for 1164 segments. In the case of the FTP session, the FTP data on port 20 was predominantly sent with congestion avoidance in operation, while the FTP session relied exclusively on slow start. For the default congestion control algorithm - "newreno" - on Solaris 11, slow start will increase the cwnd by 1 MSS for every acknowledgement received, and by 1 MSS for each RTT in congestion avoidance mode. Different pluggable congestion control algorithms operate slightly differently. For example "highspeed" will update the slow start cwnd by the number of bytes ACKed rather than the MSS. And to finish, here's a neat oneliner to visually display the distribution of congestion window values for all TCP connections to a given remote port using a quantization. In this example, only port 80 is in use and we see the majority of cwnd values for that port are in the 4096-8191 range. # dtrace -n 'tcp:::send { @q[args[4]-tcp_dport] = quantize(args[3]-tcps_cwnd); }' dtrace: description 'tcp:::send ' matched 10 probes ^C 80 value ------------- Distribution ------------- count -1 | 0 0 |@@@@@@ 5 1 | 0 2 | 0 4 | 0 8 | 0 16 | 0 32 | 0 64 | 0 128 | 0 256 | 0 512 | 0 1024 | 0 2048 |@@@@@@@@@ 8 4096 |@@@@@@@@@@@@@@@@@@@@@@@@@@ 23 8192 | 0

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• Sub query pass through

  - by SQL and the like

  Occasionally in forums and on client sites I see conditional subqueries in statements. This is where the developer has decided that it is only necessary to process some data under a certain condition.  By way of example, something like this : Create Procedure GetOrder @SalesOrderId integer, @CountDetails tinyint as Select SOH.salesorderid , case when @CountDetails = 1 then (Select count(*) from Sales.SalesOrderDetail SOD where SOH.SalesOrderID = SOD.SalesOrderID) end from sales.SalesOrderHeader...(read more)

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• Creating SharePoint sites from xml using Powershell

  - by Norgean

  It is frequently useful to create / delete web applications in a development environment. If you need to create a structure, this can quickly become tedious. Enter Powershell, xml and recursive functions. Create the structure in xml. Something like: <Sites>     <Site Name="Test 1" Url="Test1" />     <Site Name="Test 2" Url="Test2" >         <Site Name="Test 2 1" Url="Test21" >             <Site Name="Test 2 1 1" Url="Test211" />             <Site Name="Test 2 1 2" Url="Test212" />         </Site>     </Site>     <Site Name="Test 3" Url="Test3" >         <Site Name="Test 3 1" Url="Test31" />         <Site Name="Test 3 2" Url="Test32" />         <Site Name="Test 3 3" Url="Test33" >             <Site Name="Test 3 3 1" Url="Test331" />             <Site Name="Test 3 3 2" Url="Test332" />         </Site>         <Site Name="Test 3 4" Url="Test34" />     </Site> </Sites> Read this structure in Powershell, and recursively create the sites. Oh, and have cool progress dialogs, too. $snap = Get-PSSnapin | Where-Object { $_.Name -eq "Microsoft.SharePoint.Powershell" } if ($snap -eq $null) {     Add-PSSnapin "Microsoft.SharePoint.Powershell" } function CreateSites($baseUrl, $sites, [int]$progressid) {     $sitecount = $sites.ChildNodes.Count     $counter = 0     foreach ($site in $sites.Site)     {         Write-Progress -ID $progressid -Activity "Creating sites" -status "Creating $($site.Name)" -percentComplete ($counter / $sitecount*100)         $counter = $counter + 1         Write-Host "Creating $($site.Name) $($baseUrl)/$($site.Url)"         New-SPWeb -Url "$($baseUrl)/$($site.Url)" -AddToQuickLaunch:$false -AddToTopNav:$false -Confirm:$false -Name "$($site.Name)" -Template "STS#0" -UseParentTopNav:$true         if ($site.ChildNodes.Count -gt 0)         {             CreateSites "$($baseUrl)/$($site.Url)" $site ($progressid +1)         }         Write-Progress -ID $progressid -Activity "Creating sites" -status "Creating $($site.Name)" -Completed     } } # read an xml file $xml = [xml](Get-Content "C:\Projects\Powershell\sites.xml") $xml.PreserveWhitespace = $false CreateSites "http://$($env:computername)" $xml.Sites 1 Easy! Sensible real life implementations will also include templateid in the xml, will check for existence of a site before creating it, etc.

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• Adding complexity to remove duplicate code

  - by Phil

  I have several classes that all inherit from a generic base class. The base class contains a collection of several objects of type T. Each child class needs to be able to calculate interpolated values from the collection of objects, but since the child classes use different types, the calculation varies a tiny bit from class to class. So far I have copy/pasted my code from class to class and made minor modifications to each. But now I am trying to remove the duplicated code and replace it with one generic interpolation method in my base class. However that is proving to be very difficult, and all the solutions I have thought of seem way too complex. I am starting to think the DRY principle does not apply as much in this kind of situation, but that sounds like blasphemy. How much complexity is too much when trying to remove code duplication? EDIT: The best solution I can come up with goes something like this: Base Class: protected T GetInterpolated(int frame) { var index = SortedFrames.BinarySearch(frame); if (index >= 0) return Data[index]; index = ~index; if (index == 0) return Data[index]; if (index >= Data.Count) return Data[Data.Count - 1]; return GetInterpolatedItem(frame, Data[index - 1], Data[index]); } protected abstract T GetInterpolatedItem(int frame, T lower, T upper); Child class A: public IGpsCoordinate GetInterpolatedCoord(int frame) { ReadData(); return GetInterpolated(frame); } protected override IGpsCoordinate GetInterpolatedItem(int frame, IGpsCoordinate lower, IGpsCoordinate upper) { double ratio = GetInterpolationRatio(frame, lower.Frame, upper.Frame); var x = GetInterpolatedValue(lower.X, upper.X, ratio); var y = GetInterpolatedValue(lower.Y, upper.Y, ratio); var z = GetInterpolatedValue(lower.Z, upper.Z, ratio); return new GpsCoordinate(frame, x, y, z); } Child class B: public double GetMph(int frame) { ReadData(); return GetInterpolated(frame).MilesPerHour; } protected override ISpeed GetInterpolatedItem(int frame, ISpeed lower, ISpeed upper) { var ratio = GetInterpolationRatio(frame, lower.Frame, upper.Frame); var mph = GetInterpolatedValue(lower.MilesPerHour, upper.MilesPerHour, ratio); return new Speed(frame, mph); }

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• Sorting a Linked List [closed]

  - by Mohit Sehgal

  I want to sort a linked list. Here Node is class representing a node in a Linked List I have written a code to bubble sort a linked list. Program does not finishes execution. Kindly point out the mistakes. class Node { public: int data; public: Node *next; Node() { data=0;next=0; } Node(int d) { data=d; } void setData(int d) { data=d; } void print() { cout<<data<<endl; } bool operator==(Node n) { return this->data==n.data; } bool operator >(Node d) { if((this->data) > (d.data)) return true; return false; } }; class LList { public: int noOfNodes; Node *start;/*Header Node*/ LList() { start=new Node; noOfNodes=0;start=0; } void addAtFront(Node* n) { n->next=(start); start=n; noOfNodes++; } void addAtLast(Node* n) { Node *cur=(start); n->next=NULL; if(start==NULL) { start=n; noOfNodes++; return; } while(cur->next!=NULL) { cur=cur->next; } cur->next=n; noOfNodes++; } void addAtPos(Node *n,int pos) { if(pos==1) { addAtFront(n);return; } Node *cur=(start); Node *prev=NULL; int curPos=0; n->next=NULL; while(cur!=NULL) { curPos++; if(pos==curPos+1) { prev=cur; } if(pos==curPos) { n->next=cur; prev->next=n; break; } cur=cur->next; } noOfNodes++; } void removeFirst() { Node *del=start; start=start->next; delete del; noOfNodes--; return; } void removeLast() { Node *cur=start,*prev=NULL; while(cur->next!=NULL) { prev=cur; cur=cur->next; } prev->next=NULL; Node *del=cur->next; delete del; noOfNodes--; return; } void removeNodeAt(int pos) { if(pos<1) return; if(pos==1) { removeFirst();return;} int curPos=1; Node* cur=start->next; Node* prev=start; Node* del=NULL; while(curPos<pos&&cur!=NULL) { curPos++; if(curPos==pos) { del=cur; prev->next=cur->next; cur->next=NULL; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } void removeNode(Node *d) { Node *cur=start; if(*d==*cur) { removeFirst();return; } cur=start->next; Node *prev=start,*del=NULL; while(cur!=NULL) { if(*cur==*d) { del=cur; prev->next=cur->next; delete del; noOfNodes--; break; } prev=prev->next; cur=cur->next; } } int getPosition(Node data) { int pos=0; Node *cur=(start); while(cur!=NULL) { pos++; if(*cur==data) { return pos; } cur=cur->next; } return -1;//not found } Node getNode(int pos) { if(pos<1) return -1;// not a valid position else if(pos>noOfNodes) return -1; // not a valid position Node *cur=(start); int curPos=0; while(cur!=NULL) { if(++curPos==pos) return *cur; cur=cur->next; } } void reverseList()//reverse the list { Node* cur=start->next; Node* d=NULL; Node* prev=start; while(cur!=NULL) { d=cur->next; cur->next=start; start=cur; prev->next=d; cur=d; } } void sortBubble() { Node *i=start,*j=start,*prev=NULL,*temp=NULL,*after=NULL; int count=noOfNodes-1;int icount=0; while(i->next!=NULL) { j=start; after=j->next; icount=0; while(++icount!=count) { if((*j)>(*after)) { temp=after->next; after->next=j; prev->next=j->next; j->next=temp; prev=after; after=j->next; } else{ prev=j; j=after; after=after->next; } } i=i->next; count--; } } void traverse() { Node *cur=(start); int c=0; while(cur!=NULL) { // cout<<"start"<<start; c++; cur->print(); cur=cur->next; } noOfNodes=c; } ~LList() { delete start; } }; int main() { int n; cin>>n; int d; LList list; Node *node; Node *temp=new Node(2123); for(int i=0;i<n;i++) { cin>>d; node=new Node(d); list.addAtLast(node); } list.addAtPos(temp,1); cout<<"traverse\n"; list.traverse(); temp=new Node(12); list.removeNode(temp); cout<<"12 removed"; list.traverse(); list.reverseList(); cout<<"\nreversed\n"; list.traverse(); cout<<"bubble sort\n"; list.sortBubble(); list.traverse(); getch(); delete node; return 0; }

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• Not Drowning, Being Saved By a Dog

  - by Aaron Lazenby

  Really, there's no dog in this story. Just a week without travel to get some actual work done.I had plans to blog ambitiously from from Collaborate 10 (Wi-Fi was limited; iPad is still untested), but it's a much busier week than your agenda suggests.Scheduling sessions is one thing: you can count on those chunks of time being lost to the universe. It's the bumping into people in the hall and dropping in on an impromptu lunch that really knocks things out of whack.Good think too: I met with some great folks from

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• Updates about Multidimensional vs Tabular #ssas #msbi

  - by Marco Russo (SQLBI)

  I recently read the blog post from James Serra Tabular model: Not ready for prime time? (read also the comments because there are discussions about a few points raised by James) and the following post from Christian Wade Multidimensional or Tabular. In the last 2 years I worked with many companies adopting Tabular in different scenarios and I agree with some of the points expressed by James in his post (especially about missing features in Tabular if compared to Multidimensional), but I strongly disagree in others. In general, Tabular is a good choice for a new project when: the development team does not have a good knowledge of Multidimensional and MDX (DAX is faster to learn, not so easy as it is sold by MS, but definitely easier than MDX) you don’t need calculations based on hierarchies (common in certain financial applications, but not so common as it could seem) there are important calculations based on distinct count measures there are complex calculations based on many-to-many relationships Until now, I never suggested to migrate an existing Multidimensional model to a Tabular one. There should be very important reasons for that, such as performance issues in distinct count and many-to-many relationships that cannot be easily solved by optimizing the Multidimensional model, but I still never encountered this scenario. I would say that in 80% of the new projects, you might use either Multidimensional or Tabular and the real difference is the time-to-market depending on the skills of the development team. So it’s not strange that who is used to Multidimensional is not moving to Tabular, not getting a particular benefit from the new model unless specific requirements exist. The recent DAXMD feature that allows using SharePoint Power View on Multidimensional is a really important one, even if I’d like having also Excel Power View enabled for this scenario (this should be just a question of time). Another scenario in which I’m seeing a growing adoption of Tabular is in companies that creates models for their product/service and do that by using XMLA or Tabular AMO 2012. I am used to call them ISVs, even if those providing services cannot be really defined in this way. These companies are facing the multitenancy challenge with Tabular and even if this is a niche market, I see some potential here, because adopting Tabular seems a much more natural choice than Multidimensional in those scenario where an analytical engine has to be embedded to deliver one of the features of a larger product/service delivered to customers. I’d like to see other feedbacks in the comments: tell your story of choosing between Tabular and Multidimensional in a BI project you started with SQL Server 2012, thanks!

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• How to calculate the covariance in T-SQL

  - by Peter Larsson

  DECLARE @Sample TABLE         (             x INT NOT NULL,             y INT NOT NULL         ) INSERT  @Sample VALUES  (3, 9),         (2, 7),         (4, 12),         (5, 15),         (6, 17) ;WITH cteSource(x, xAvg, y, yAvg, n) AS (         SELECT  1E * x,                 AVG(1E * x) OVER (PARTITION BY (SELECT NULL)),                 1E * y,                 AVG(1E * y) OVER (PARTITION BY (SELECT NULL)),                 COUNT(*) OVER (PARTITION BY (SELECT NULL))         FROM    @Sample ) SELECT  SUM((x - xAvg) *(y - yAvg)) / MAX(n) AS [COVAR(x,y)] FROM    cteSource

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• 3D Model not translating correctly (visually)

  - by ChocoMan

  In my first image, my model displays correctly: But when I move the model's position along the Z-axis (forward) I get this, yet the Y-axis doesnt change. An if I keep going, the model disappears into the ground: Any suggestions as to how I can get the model to translate properly visually? Here is how Im calling the model and the terrain in draw(): cameraPosition = new Vector3(camX, camY, camZ); // Copy any parent transforms. Matrix[] transforms = new Matrix[mShockwave.Bones.Count]; mShockwave.CopyAbsoluteBoneTransformsTo(transforms); Matrix[] ttransforms = new Matrix[terrain.Bones.Count]; terrain.CopyAbsoluteBoneTransformsTo(ttransforms); // Draw the model. A model can have multiple meshes, so loop. foreach (ModelMesh mesh in mShockwave.Meshes) { // This is where the mesh orientation is set, as well // as our camera and projection. foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationY(modelRotation) * Matrix.CreateTranslation(modelPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, modelPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); mesh.Draw(); } //Terrain test foreach (ModelMesh meshT in terrain.Meshes) { foreach (BasicEffect effect in meshT.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = ttransforms[meshT.ParentBone.Index] * Matrix.CreateRotationY(0) * Matrix.CreateTranslation(terrainPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, terrainPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); meshT.Draw(); DrawText(); } base.Draw(gameTime); } Im suspecting that there may be something wrong with how I'm handling my camera. The model rotates fine on its Y-axis.

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• How to add information indicators to a Launcher icon from a script?

  - by Paddy Landau

  Some applications place informational text over their icons in the Launcher. For example, Thunderbird shows the unread message count, and Update Manager shows the number of updates available and a progress bar. The image shows these two examples: I have created some Bash scripts that use yad (a Zenity fork), which adds an icon to the Launcher while running. I would like to know how I can create my own information overlay within my script for those icons.

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• Does Google rate the webpage by amount of visits?

  - by petiar

  Hi there, there is quite extensive discussion about this topic on another website and I am really losing my confidence. The thing is that I claim that the amount (count) of visits is NOT a criteria for increasing the PR of the particular web because: a) Google just doesn't know about every single visit on a webpage (in case it's not using GA) b) Google just would not rate by something what Google actually affects Thanks for your opinions. Peter.

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• NDepend 4.0 Released

  - by Anthony Trudeau

  Last week version 4.0 of NDepend was released.  NDepend is a Visual Studio add-in designed for intense code analysis with the goal of high quality code.  A month ago I wrapped up my evaluation of the previous version of NDepend. The new version contains many minor changes, several bug fixes, and adds about 50 new code rules.  The version also adds support for Visual Studio 11, .NET Framework 4.5, and SilverLight 5.0.  But, the biggest change was the shift from CQL to CQLinq. Introducing CQLinq The latest version replaces the CQL rules language with CQLinq (CQL is still an option although the editor is buried).  As you might guess CQLinq is a flavor of Linq designed specifically for the code rules. The best way to illustrate the differences is with an example.  I used the following CQL example in Part 3 of my review: WARN IF Count > 0 IN SELECT TYPES WHERE IsInterface AND !NameLike “I” This same query looks like this when implemented in CQLinq: warnif count > 0 from t in Types where t.IsInterface == true && !t.NameLike(“I”) select t I like the syntax and it is a natural fit, but I found writing the queries frustrating in the Queries and Rules Edit window.  The Queries and Rules Edit window replaces the CQL Query Edit window.  The new editor has the same style of Intellisense as the previous editor.  However, it has a few annoyances.  The error indicator is a red block.  It has the tendency of obscuring your cursor.  Additionally, writing CQLing queries is like writing plain old Linq queries, so the fact that the editor uses Enter to select from Intellisense instead of Tab is jarring.  These issues can be an obstacle to writing queries quickly.CQLinq makes it possible to write rules that weren't possible before.  Additionally, a JustMyCode domain is now possible making it easy to eliminate generated code from the analysis.Should you Buy? I recommend NDepend overall.  It has some rough points for me that I have detailed in my earlier evaluation (starting here).  But, it’s definitely worth the money.  The bigger question is: should I pay for the upgrade to 4.0?  At this point I’m on the fence, but I would go for it if you need support for Visual Studio 2011, .NET Framework 4.5, or Silverlight 5.0; or if you need one of the many rules that weren't possible before CQLinq. Disclaimer: Patrick Smacchia contacted me about reviewing NDepend. I received a free license in return for sharing my experiences and talking about the capabilities of the add-in on this site. There is no expectation of a positive review elicited from the author of NDepend. Resources: NDepend Release Notes

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• Why does my 3D model not translate the way I expect? [closed]

  - by ChocoMan

  In my first image, my model displays correctly: But when I move the model's position along the Z-axis (forward) I get this, yet the Y-axis doesnt change. An if I keep going, the model disappears into the ground: Any suggestions as to how I can get the model to translate properly visually? Here is how Im calling the model and the terrain in draw(): cameraPosition = new Vector3(camX, camY, camZ); // Copy any parent transforms. Matrix[] transforms = new Matrix[mShockwave.Bones.Count]; mShockwave.CopyAbsoluteBoneTransformsTo(transforms); Matrix[] ttransforms = new Matrix[terrain.Bones.Count]; terrain.CopyAbsoluteBoneTransformsTo(ttransforms); // Draw the model. A model can have multiple meshes, so loop. foreach (ModelMesh mesh in mShockwave.Meshes) { // This is where the mesh orientation is set, as well // as our camera and projection. foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationY(modelRotation) * Matrix.CreateTranslation(modelPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, modelPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); mesh.Draw(); } //Terrain test foreach (ModelMesh meshT in terrain.Meshes) { foreach (BasicEffect effect in meshT.Effects) { effect.EnableDefaultLighting(); effect.PreferPerPixelLighting = true; effect.World = ttransforms[meshT.ParentBone.Index] * Matrix.CreateRotationY(0) * Matrix.CreateTranslation(terrainPosition); // Looking at the model (picture shouldnt change other than rotation) effect.View = Matrix.CreateLookAt(cameraPosition, terrainPosition, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView( MathHelper.ToRadians(45.0f), aspectRatio, 1.0f, 10000.0f); effect.TextureEnabled = true; } // Draw the mesh, using the effects set above. prepare3d(); meshT.Draw(); DrawText(); } base.Draw(gameTime); } I'm suspecting that there may be something wrong with how I'm handling my camera. The model rotates fine on its Y-axis.

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• Spatial data from shapefiles (for T-SQL Tuesday #006)

  - by Rob Farley

  I’m giving a presentation on May 12th at the Adelaide .Net User Group, around the topic of spatial data, and in particular, the visualization of said data. Given that it’s about one the larger types, this post should also count towards Michael Coles’ T-SQL Tuesday on BLOB data . I wrote recently about my experience with exploded data , but what I didn’t go on to talk about was how using a shapefile like this would translate into a scenario with a much larger number of shapes, such as all the postcode...(read more)

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• How many per-core licenses do I need?

  - by GavinPayneUK

    With SQL Server 2012, your licensing requirements can chose to use or be required to use a per-core model depending on the edition you’re deploying. This is a change to previous editions which used a per-CPU socket model that made counting how many per-CPU licences you needed easier – cores and HyperThreading didn’t influence the CPU socket count.  Any complications which people did have typically came from running SQL Server in a virtualised environment, was a vCPU a socket or did licensing...(read more)

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• Avg. Visit Duration 00:00:00 conclusion

  - by user1592845

  What can I predict when I see in Google Analytics that total visits by search for some day are 93 visits while 70 visits of them have the value 00:00:00 for Avg. Visit Duration? Did those visits made by robots? or How could they regarded as visits while they don't spend any time on the website? Or this is dysfunction of the Google's Analytics script by which it does not able to count the visit time?

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• Is it okay to call exception-triggered debugging "post-mortem debugging"?

  - by cool-RR

  I heard the term "post-mortem debugging", and Wikipedia says it's debugging done after the program has crashed. I often debug Python apps using a debugger that stops execution once an important-enough exception has been raised. Then I can use the debug probe to investigate. Does this count as "post-mortem debugging"? Because the program doesn't really crash. EDIT: If the answer is no, then what name would you use for the kind of debugging that I described?

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• Reach Local Proxy Page - Duplicate content?

  - by Simon Bennett

  We have a client who has instructed Reach Local to manage their paid SEO work etc. RL have created a proxy version of the page at http://example-px.rtrk.co.uk which mirrors the existing site completely. Would I be correct in assuming that this would count as duplicate content and one or both of the sites would be penalized because of this? And would the addition of a rel="canonical" meta-tag on the proxy site assist with this? Many thanks in advance.

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• Let Oracle University help you become a Certified Implementation Specialist

  - by user12875760

  Oracle recognizes partner competency skills and commitment through the new Oracle PartnerNetwork Specialized program and offers a variety of accreditations that count towards OPN Certification. Be Recognized! Validate your knowledge and get the credit you deserve by passing the Specialist exams offered across Oracle's portfolio of products and solutions. Pass the exam(s) and get your OPN Specialist Certificate! Read more by clicking here

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• London 16th June User-Group Review

  - by NeilHambly

  London SQL Server User Group (Host by IMGROUP) 16 th June One of my own failings of past, has been not doing a follow-up on the User-Group events I attend and frequently speak @, with post event blog & slide decks, this last Thursday was just one such occasion so here is the blog I promised We had somewhere around the mid 30's attend (I forgot to count it seems) and I think we all had a wonderful evening covering both SQL & non-SQL topics during the evening (let me know you thoughts on...(read more)

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• Inline template efficiency

  - by Darryl Gove

  I like inline templates, and use them quite extensively. Whenever I write code with them I'm always careful to check the disassembly to see that the resulting output is efficient. Here's a potential cause of inefficiency. Suppose we want to use the mis-named Leading Zero Detect (LZD) instruction on T4 (this instruction does a count of the number of leading zero bits in an integer register - so it should really be called leading zero count). So we put together an inline template called lzd.il looking like: .inline lzd lzd %o0,%o0 .end And we throw together some code that uses it: int lzd(int); int a; int c=0; int main() { for(a=0; a<1000; a++) { c=lzd(c); } return 0; } We compile the code with some amount of optimisation, and look at the resulting code: $ cc -O -xtarget=T4 -S lzd.c lzd.il $ more lzd.s .L77000018: /* 0x001c 11 */ lzd %o0,%o0 /* 0x0020 9 */ ld [%i1],%i3 /* 0x0024 11 */ st %o0,[%i2] /* 0x0028 9 */ add %i3,1,%i0 /* 0x002c */ cmp %i0,999 /* 0x0030 */ ble,pt %icc,.L77000018 /* 0x0034 */ st %i0,[%i1] What is surprising is that we're seeing a number of loads and stores in the code. Everything could be held in registers, so why is this happening? The problem is that the code is only inlined at the code generation stage - when the actual instructions are generated. Earlier compiler phases see a function call. The called functions can do all kinds of nastiness to global variables (like 'a' in this code) so we need to load them from memory after the function call, and store them to memory before the function call. Fortunately we can use a #pragma directive to tell the compiler that the routine lzd() has no side effects - meaning that it does not read or write to memory. The directive to do that is #pragma no_side_effect(<routine name), and it needs to be placed after the declaration of the function. The new code looks like: int lzd(int); #pragma no_side_effect(lzd) int a; int c=0; int main() { for(a=0; a<1000; a++) { c=lzd(c); } return 0; } Now the loop looks much neater: /* 0x0014 10 */ add %i1,1,%i1 ! 11 ! { ! 12 ! c=lzd(c); /* 0x0018 12 */ lzd %o0,%o0 /* 0x001c 10 */ cmp %i1,999 /* 0x0020 */ ble,pt %icc,.L77000018 /* 0x0024 */ nop

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• SharePoint 2013 Certifications - MCSE

  - by KunaalKapoor

  Microsoft Certified Solutions Expert (MCSE): SharePoint.Yes you read it right :) SharePoint 2013 Certifications are here... The two certifications mentioned below are expected to be published on February 05, 2013. And will count as credit to the new MCSE certificate. Exams Details:70-331 (Core Solutions of Microsoft SharePoint Server 2013)70-332 (Advanced Solutions of Microsoft SharePoint Server 2013)Classroom Trainings:Course 40028A: First Look Clinic: What’s New for IT Professionals in Microsoft SharePoint Server 2013Course 40027A: First Look Clinic: What’s New for Developers in Microsoft SharePoint 2013Time to prep... Next Stop MCSE...  :)

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• 2010 Chicago Code Coming In May

  - by Tim Murphy

  The Lake Count .NET User Group is putting on it’s second Chicago Code Camp on May 1st.  I would encourage everyone to come out and participate in the Chicago area .NET community.  You can register here.  Better yet come of with a presentation of your own.  I have submitted an abstract for a presentation on Office Open XML. del.icio.us Tags: Chicago Code Camp,presentations,Office Open XML,LCNUG

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• Do Follow Or No Follow (SEO Tips)

  By default, WordPress blogs use a rel="nofollow" attribute, so when you read of Do Follow Blogs, these are blogs that have used a plugin that removes the nofollow attribute. Comments then that contain links back to the poster count as backlinks for their sites.

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• WHERE x = @x OR @x IS NULL

  - by steveh99999

  Every SQL DBA and developer should read the blog of MVP Erland Sommarskog – but particularly  his article on dynamic search conditions in T-SQL. I’ve linked above to his SQL 2005 article but his 2008 version is also a must-read. I seem to regularly come across uses of the SQL in the title above… Erland’s article explains in detail why this is inefficient, but I came across a nice example recently… A stored procedure contained the following code :- WHERE @Name is null or [Name] like @Name as a nonclustered index exists on the Name column, you might assume this would be handled efficiently by SQL Server. However, I got the following output from SET STATISTICS IO Table 'xxxxx'. Scan count 15, logical reads 47760, physical reads 9, read-ahead reads 13872, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Note the high number of logical reads… After a bit of investigation, we found that @Name could never actually be set to NULL in this particular example. ie the @x IS NULL was spurious… So, we changed the call to WHERE  [Name] like @Name Now, how much more efficient is this code ? Table 'xxxxx'. Scan count 3, logical reads 24, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0 A nice easy win in this case…… a full index scan has been replaced by a significantly more efficient index seek. I managed to recreate the same behaviour on Adventureworks – here’s a quick query to demonstrate :- USE adventureworks SET STATISTICS IO ON DECLARE @id INT = 51721 SELECT * FROM Sales.SalesOrderDetail WHERE @id IS NULL OR salesorderid = @id SELECT * FROM Sales.SalesOrderDetail WHERE salesorderid = @id Take a look at the STATISTICS IO output and compare the actual query plans used to prove the impact of  WHERE @id IS NULL. And just to follow some of Erland’s advice – here’s how you could get similar performance if it was possible that @id could actually sometimes contain NULL. DECLARE @sql NVARCHAR(4000), @parameterlist NVARCHAR(4000) DECLARE @id INT = 51721 – or change to NULL to prove query is functionally correct SET @sql = 'SELECT * FROM Sales.SalesOrderDetail WHERE 1 = 1' IF @id IS NOT NULL SET @sql = @sql + ' AND salesorderid = @id' IF @id IS NULL SET @sql = @sql + ' AND salesorderid IS NULL' SET @parameterlist = '@id INT' EXEC sp_executesql @sql, @parameterlist,@id Sometimes I think we focus too much on hardware and SQL Server configuration – when really the answer is focus on writing efficient SQL.

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