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• Unable to Sign in to the Microsoft Online Services Signin application from Windows 7 client located behind ISA firewall

  - by Ravindra Pamidi

  A while ago i helped a customer troubleshoot authentication problem with Microsoft Online Services Signin application.  This customer was evaluating Microsoft BPOS (Business Productivity Online Services) and was having trouble using the single sign on application behind ISA 2004 firewall.The network structure is fairly simple with single Windows 2003 Active Directory domain and Windows 7 clients. On a successful logon to the Microsoft Online Services Signin application, this application provides single signon functionality to all of Microsoft online services in the BPOS package. Symptoms:When trying to signin it fails with error "The service is currently unavailable. Please try again later. If problems continue, contact your service administrator". If ISA 2004 firewall is removed from the picture the authentication succeeds.Troubleshooting: Enabled ISA Server firewall logging along with Microsoft Network Monitor tool on the Windows 7 Client while reproducing the issue. Analysis of the ISA Server Firewall logs and Microsoft Network capture revealed that the Microsoft Online Services Sign In application when sending request to ISA Server does not send the domain credentials and as a result ISA Server responds with an error code of HTTP 407 Proxy authentication required listing out the supported authentication mechanisms.  The application in question is expected to send the credentials of the domain user in response to this request. However in this case, it fails to send the logged on user's domain credentials. Bit of researching on the Internet revealed that The "Microsoft Online Services Sign In" application by default does not support Outbound Internet Proxy authentication. In order for it to send the logged on user's domain credentials we had to make  changes to its configuration file "SignIn.exe.config" located under "Program Files\Microsoft Online Services\Sign In" folder. Step by Step details to configure the configuration file are documented on Microsoft TechNet website given below.  Configure your outbound authenticating proxy serverhttp://www.microsoft.com/online/help/en-us/helphowto/cc54100d-d149-45a9-8e96-f248ecb1b596.htm After the above problem was addressed we were still not able to use the "Microsoft Online Services Sign In" application and it failed with the same error.  Analysis of another network capture revealed that the application in question is now sending the required credentials and the connection seems to terminate at a later stage. Enabled verbose logging for the "Microsoft Online Services Sign In" application and then reproduced the problem. Analysis of the logs revealed a time difference between the local client and Microsoft Online services server of around seven minutes which is above the acceptable time skew of five minutes. Excerpt from Microsoft Online Services Sign In application verbose log:  1/26/2012 1:57:51 PM Verbose SingleSignOn.GetSSOGenericInterface SSO Interface URL: https://signinservice.apac.microsoftonline.com/ssoservice/UID1/26/2012 1:57:52 PM Exception SSOSignIn.SignIn The security timestamp is invalid because its creation time ('2012-01-26T08:34:52.767Z') is in the future. Current time is '2012-01-26T08:27:52.987Z' and allowed clock skew is '00:05:00'.1/26/2012 1:57:52 PM Exception SSOSignIn.SignIn  Although the Windows 7 Clients successfully synchronized time to the domain controller for the domain, the domain controller was not configured to synchronize time with external NTP servers. This caused a gradual drift in time on the network thus resulting in the above issue. Reconfigured the domain controller holding the PDC FSMO role to synchronize time with external time source ( time.nist.gov ) and edited the system policy on the ISA server firewall to allow NTP traffic to time.nist.gov Configure the time source for the forest:Windows Time Servicehttp://technet.microsoft.com/en-us/library/cc794937(WS.10).aspx Forced synchronization of Windows time using the command w32tm /resync on the domain controller and later on the clients each of which had corrected the seven minutes difference. This resolved the problem with logon to Microsoft Online Services Sign In.

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• Error X3650 when compiling shader in XNA

  - by Saikai

  I'm attempting to convert the XBDEV.NET Mosaic Shader for use in my XNA project and having trouble. The compiler errors out because of the half globals. At first I tried replacing the globals and just writing the variables explicitly in the code, but that garbles the Output. Next I tried replacing all the half with float vars, but that still garbles the resulting Image. I call the effect file from SpriteBatch.Begin(). Is there a way to convert this shader to the new pixel shader conventions? Are there any good tutorials for this topic? Here is the shader file for reference: /*****************************************************************************/ /* File: tiles.fx Details: Modified version of the NVIDIA Composer FX Demo Program 2004 Produces a tiled mosaic effect on the output. Requires: Vertex Shader 1.1 Pixel Shader 2.0 Modified by: [email protected] (www.xbdev.net) */ /*****************************************************************************/ float4 ClearColor : DIFFUSE = { 0.0f, 0.0f, 0.0f, 1.0f}; float ClearDepth = 1.0f; /******************************** TWEAKABLES *********************************/ half NumTiles = 40.0; half Threshhold = 0.15; half3 EdgeColor = {0.7f, 0.7f, 0.7f}; /*****************************************************************************/ texture SceneMap : RENDERCOLORTARGET < float2 ViewportRatio = { 1.0f, 1.0f }; int MIPLEVELS = 1; string format = "X8R8G8B8"; string UIWidget = "None"; >; sampler SceneSampler = sampler_state { texture = <SceneMap>; AddressU = CLAMP; AddressV = CLAMP; MIPFILTER = NONE; MINFILTER = LINEAR; MAGFILTER = LINEAR; }; /***************************** DATA STRUCTS **********************************/ struct vertexInput { half3 Position : POSITION; half3 TexCoord : TEXCOORD0; }; /* data passed from vertex shader to pixel shader */ struct vertexOutput { half4 HPosition : POSITION; half2 UV : TEXCOORD0; }; /******************************* Vertex shader *******************************/ vertexOutput VS_Quad( vertexInput IN) { vertexOutput OUT = (vertexOutput)0; OUT.HPosition = half4(IN.Position, 1); OUT.UV = IN.TexCoord.xy; return OUT; } /********************************** pixel shader *****************************/ half4 tilesPS(vertexOutput IN) : COLOR { half size = 1.0/NumTiles; half2 Pbase = IN.UV - fmod(IN.UV,size.xx); half2 PCenter = Pbase + (size/2.0).xx; half2 st = (IN.UV - Pbase)/size; half4 c1 = (half4)0; half4 c2 = (half4)0; half4 invOff = half4((1-EdgeColor),1); if (st.x > st.y) { c1 = invOff; } half threshholdB = 1.0 - Threshhold; if (st.x > threshholdB) { c2 = c1; } if (st.y > threshholdB) { c2 = c1; } half4 cBottom = c2; c1 = (half4)0; c2 = (half4)0; if (st.x > st.y) { c1 = invOff; } if (st.x < Threshhold) { c2 = c1; } if (st.y < Threshhold) { c2 = c1; } half4 cTop = c2; half4 tileColor = tex2D(SceneSampler,PCenter); half4 result = tileColor + cTop - cBottom; return result; } /*****************************************************************************/ technique tiles { pass p0 { VertexShader = compile vs_1_1 VS_Quad(); ZEnable = false; ZWriteEnable = false; CullMode = None; PixelShader = compile ps_2_0 tilesPS(); } }

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• Musings on the launch of SQL Monitor

  - by Phil Factor

  For several years, I was responsible for the smooth running of a large number of enterprise database servers. We ran a network monitoring tool that was primitive by today’s standards but which performed the useful function of polling every system, including all the Servers in my charge. It ran a configurable script for each service that you needed to monitor that was merely required to return one of a number of integer values. These integer values represented the pain level of the service, from 10 (“hurtin’ real bad”) to 1 (“Things is great”). Not only could you program the visual appearance of each server on the network diagram according to the value of the integer, but you could even opt to run a sound file. Very soon, we had a large TFT Screen, high on the wall of the server room, with every server represented by an icon, and a speaker next to it that would give out a series of grunts, groans, snores, shrieks and funeral marches, depending on the problem. One glance at the display, and you could dive in with iSQL/QA/SSMS and check what was going on with your favourite diagnostic tools. If you saw a server icon burst into flames on the screen or droop like a jelly, you dropped your mug of coffee to do it.  It was real fun, but I remember it more for the huge difference it made to have that real-time visibility into how your servers are performing. The management soon stopped making jokes about the real reason we wanted the TFT screen. (It rendered DVDs beautifully they said; particularly flesh-tints). If you are instantly alerted when things start to go wrong, then there was a good chance you could fix it before being alerted to the problem by the users of the system.  There is a world of difference between this sort of tool, one that gives whoever is ‘on watch’ in the server room the first warning of a potential problem on one of any number of servers, and the breed of tool that attempts to provide some sort of prosthetic DBA Brain. I like to get the early warning, to get the right information to help to diagnose a problem: No auto-fix, but just the information. I prefer to leave the task of ascertaining the exact cause of a problem to my own routines, custom code, intuition and forensic instincts. A simulated aircraft cockpit doesn’t do anything for me, especially before I know where I should be flying.  Time has moved on, and that TFT screen is now, with SQL Monitor, an iPad or any other mobile or static device that can support a browser. Rather than trying to reproduce the conceptual topology of the servers, it lists them in their groups so as to give a display that scales with the increasing number of databases you monitor.  It gives the history of the major events and trends for the servers. It gives the icons and colours that you can spot out of the corner of your eye, but goes on to give you just enough information in drill-down to give you a much clearer idea of where to look with your DBA tools and routines. It doesn't swamp you with information.  Whereas a few server and database-level problems are pretty easily fixed, others depend on judgement and experience to sort out.  Although the idea of an application that automates the bulk of a DBA’s skills is attractive to many, I can’t see it happening soon. SQL Server’s complexity increases faster than the panaceas can be created. In the meantime, I believe that the best way of helping  DBAs  is to make the monitoring process as simple and effective as possible,  and provide the right sort of detail and ‘evidence’ to allow them to decide on the fix. In the end, it is still down to the skill of the DBA.

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• WiFi stops working after a while in Lenovo ThinkPad W520 (Ubuntu 12.04)

  - by el10780

  After several minutes(I do not know how many) there is no internet connection on my laptop via Wi-Fi.Ubuntu doesn't show any kind of message that my WiFi was disconnected neither there is a signal drop,but suddenly Firefox stops connecting to web pages.I checked my modem/router and it seems that it is working fine.I tried also to reboot the WiFi device and nothing happens.The only thing that it makes it work again is a reboot of the system and if I do not want to do a reboot then I am enforced to connect to the Internet using Ethernet cable.Does anybody know what is happening? ## Some Hardware info that might be helpful ## el10780@ThinkPad-W520:~$ sudo lshw -class network *-network description: Ethernet interface product: 82579LM Gigabit Network Connection vendor: Intel Corporation physical id: 19 bus info: pci@0000:00:19.0 logical name: eth0 version: 04 serial: f0:de:f1:f1:be:10 size: 100Mbit/s capacity: 1Gbit/s width: 32 bits clock: 33MHz capabilities: pm msi bus_master cap_list ethernet physical tp 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=e1000e driverversion=1.5.1-k duplex=full firmware=0.13-3 ip=192.168.0.10 latency=0 link=yes multicast=yes port=twisted pair speed=100Mbit/s resources: irq:50 memory:f3a00000-f3a1ffff memory:f3a2b000-f3a2bfff ioport:6080(size=32) *-network description: Wireless interface product: Centrino Advanced-N + WiMAX 6250 vendor: Intel Corporation physical id: 0 bus info: pci@0000:03:00.0 logical name: wlan0 version: 5e serial: 64:80:99:63:14:74 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-26-generic firmware=41.28.5.1 build 33926 ip=192.168.0.6 latency=0 link=yes multicast=yes wireless=IEEE 802.11abgn resources: irq:52 memory:f3900000-f3901fff *-network description: Ethernet interface physical id: 1 bus info: usb@2:1.3 logical name: wmx0 serial: 00:1d:e1:53:b2:e8 capabilities: ethernet physical configuration: driver=i2400m firmware=i6050-fw-usb-1.5.sbcf link=no el10780@ThinkPad-W520:~$ lspci 00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:01.0 PCI bridge: Intel Corporation Xeon E3-1200/2nd Generation Core Processor Family PCI Express Root Port (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:16.0 Communication controller: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 (rev 04) 00:16.3 Serial controller: Intel Corporation 6 Series/C200 Series Chipset Family KT Controller (rev 04) 00:19.0 Ethernet controller: Intel Corporation 82579LM Gigabit Network Connection (rev 04) 00:1a.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset Family High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 1 (rev b4) 00:1c.1 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 2 (rev b4) 00:1c.3 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 4 (rev b4) 00:1c.4 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 5 (rev b4) 00:1c.6 PCI bridge: Intel Corporation 6 Series/C200 Series Chipset Family PCI Express Root Port 7 (rev b4) 00:1d.0 USB controller: Intel Corporation 6 Series/C200 Series Chipset Family USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation QM67 Express Chipset Family LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation 6 Series/C200 Series Chipset Family 6 port SATA AHCI Controller (rev 04) 00:1f.3 SMBus: Intel Corporation 6 Series/C200 Series Chipset Family SMBus Controller (rev 04) 01:00.0 VGA compatible controller: NVIDIA Corporation GF108 [Quadro 1000M] (rev a1) 03:00.0 Network controller: Intel Corporation Centrino Advanced-N + WiMAX 6250 (rev 5e) 0d:00.0 System peripheral: Ricoh Co Ltd Device e823 (rev 08) 0d:00.3 FireWire (IEEE 1394): Ricoh Co Ltd R5C832 PCIe IEEE 1394 Controller (rev 04) 0e:00.0 USB controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04) el10780@ThinkPad-W520:~$ rfkill list all 0: hci0: Bluetooth Soft blocked: no Hard blocked: no 1: tpacpi_bluetooth_sw: Bluetooth Soft blocked: no Hard blocked: no 2: phy0: Wireless LAN Soft blocked: no Hard blocked: no 3: i2400m-usb:2-1.3:1.0: WiMAX Soft blocked: yes Hard blocked: no The weirdest thing is this screenshot which I took after running the **Additional Drivers** program.I mean I have a NVidia Quadro 1000M and my Intel Centrino WiFi Card and this shows that there are not proprietay drivers for my system. http://imageshack.us/photo/my-images/268/screenshotfrom201207062.png/

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• NFJS Central Iowa Software Symposium Des Moines Trip Report

  - by reza_rahman

  As some of you may be aware, I recently joined the well-respected US based No Fluff Just Stuff (NFJS) Tour. If you work in the US and still don't know what the No Fluff Just Stuff (NFJS) Tour is, you are doing yourself a very serious disfavor. NFJS is by far the cheapest and most effective way to stay up to date through some world class speakers and talks. Following the US cultural tradition of old-fashioned roadshows, NFJS is basically a set program of speakers and topics offered at major US cities year round. The NFJS Central Iowa Software Symposium was held August 8 - 10 in Des Moines. The attendance at the event and my sessions was moderate by comparison to some of the other shows. It is one of the few events of it's kind that take place this part the country so it is extremely important. I had five talks total over two days, more or less back-to-back. The first one was my JavaScript + Java EE 7 talk titled "Using JavaScript/HTML5 Rich Clients with Java EE 7". This talk is basically about aligning EE 7 with the emerging JavaScript ecosystem (specifically AngularJS). The slide deck for the talk is here: JavaScript/HTML5 Rich Clients Using Java EE 7 from Reza Rahman The demo application code is posted on GitHub. The code should be a helpful resource if this development model is something that interests you. Do let me know if you need help with it but the instructions should be fairly self-explanatory. I am delivering this material at JavaOne 2014 as a two-hour tutorial. This should give me a little more bandwidth to dig a little deeper, especially on the JavaScript end. The second talk (on the second day) was our flagship Java EE 7/8 talk. Currently the talk is basically about Java EE 7 but I'm slowly evolving the talk to transform it into a Java EE 8 talk as we move forward. The following is the slide deck for the talk: JavaEE.Next(): Java EE 7, 8, and Beyond from Reza Rahman The next talk I delivered was my Cargo Tracker/Java EE + DDD talk. This talk basically overviews DDD and describes how DDD maps to Java EE using code examples/demos from the Cargo Tracker Java EE Blue Prints project. Applied Domain-Driven Design Blue Prints for Java EE from Reza Rahman The third was my talk titled "Using NoSQL with ~JPA, EclipseLink and Java EE". The talk covers an interesting gap that there is surprisingly little material on out there. The talk has three parts -- a birds-eye view of the NoSQL landscape, how to use NoSQL via a JPA centric facade using EclipseLink NoSQL, Hibernate OGM, DataNucleus, Kundera, Easy-Cassandra, etc and how to use NoSQL native APIs in Java EE via CDI. The slides for the talk are here: Using NoSQL with ~JPA, EclipseLink and Java EE from Reza Rahman The JPA based demo is available here, while the CDI based demo is available here. Both demos use MongoDB as the data store. Do let me know if you need help getting the demos up and running. I finishd off the event with a talk titled Building Java HTML5/WebSocket Applications with JSR 356. The talk introduces HTML 5 WebSocket, overviews JSR 356, tours the API and ends with a small WebSocket demo on GlassFish 4. The slide deck for the talk is posted below. Building Java HTML5/WebSocket Applications with JSR 356 from Reza Rahman The demo code is posted on GitHub: https://github.com/m-reza-rahman/hello-websocket. My next NFJS show is the Greater Atlanta Software Symposium on September 12 - 14. Here's my tour schedule so far, I'll keep you up-to-date as the tour goes forward: September 12 - 14, Atlanta. September 19 - 21, Boston. October 17 - 19, Seattle. I hope you'll take this opportunity to get some updates on Java EE as well as the other useful content on the tour?

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• PASS Summit 2013 Review

  - by Ajarn Mark Caldwell

  As a long-standing member of PASS who lives in the greater Seattle area and has attended about nine of these Summits, let me start out by saying how GREAT it was to go to Charlotte, North Carolina this year.  Many of the new folks that I met at the Summit this year, upon hearing that I was from Seattle, commented that I must have been disappointed to have to travel to the Summit this year after 5 years in a row in Seattle.  Well, nothing could be further from the truth.  I cheered loudly when I first heard that the 2013 Summit would be outside Seattle.  I have many fond memories of trips to Orlando, Florida and Grapevine, Texas for past Summits (missed out on Denver, unfortunately).  And there is a funny dynamic that takes place when the conference is local.  If you do as I have done the last several years and saved my company money by not getting a hotel, but rather just commuting from home, then both family and coworkers tend to act like you’re just on a normal schedule.  For example, I have a young family, and my wife and kids really wanted to still see me come home “after work”, but there are a whole lot of after-hours activities, social events, and great food to be enjoyed at the Summit each year.  Even more so if you really capitalize on the opportunities to meet face-to-face with people you either met at previous summits or have spoken to or heard of, from Twitter, blogs, and forums.  Then there is also the lovely commuting in Seattle traffic from neighboring cities rather than the convenience of just walking across the street from your hotel.  So I’m just saying, there are really nice aspects of having the conference 2500 miles away. Beyond that, the training was fantastic as usual.  The SQL Server community has many outstanding presenters and experts with deep knowledge of the tools who are extremely willing to share all of that with anyone who wants to listen.  The opening video with PASS President Bill Graziano in a NASCAR race turned dream sequence was very well done, and the keynotes, as usual, were great.  This year I was particularly impressed with how well attended were the Professional Development sessions.  Not too many years ago, those were very sparsely attended, but this year, the two that I attended were standing-room only, and these were not tiny rooms.  I would say this is a testament to both the maturity of the attendees realizing how important these topics are to career success, as well as to the ever-increasing skills of the presenters and the program committee for selecting speakers and topics that resonated with people.  If, as is usually the case, you were not able to get to every session that you wanted to because there were just too darn many good ones, I encourage you to get the recordings. Overall, it was a great time as these events always are.  It was wonderful to see old friends and make new ones, and the people of Charlotte did an awesome job hosting the event and letting their hospitality shine (extra kudos to SQLSentry for all they did with the shuttle, maps, and other event sponsorships).  We’re back in Seattle next year (it is a release year, after all) but I would say that with the success of this year’s event, I strongly encourage the Board and PASS HQ to firmly reestablish the location rotation schedule.  I’ll even go so far as to suggest standardizing on an alternating Seattle – Charlotte schedule, or something like that. If you missed the Summit this year, start saving now, and register early, so you can join us!

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• Scenarios for Throwing Exceptions

  - by Joe Mayo

  I recently came across a situation where someone had an opinion that differed from mine of when an exception should be thrown. This particular case was an issue opened on LINQ to Twitter for an Exception on EndSession.  The premise of the issue was that the poster didn’t feel an exception should be raised, regardless of authentication status.  As first, this sounded like a valid point.  However, I went back to review my code and decided not to make any changes. Here's my rationale: 1. The exception doesn’t occur if the user is authenticated when EndAccountSession is called. 2. The exception does occur if the user is not authenticated when EndAccountSession is called. 3. The exception represents the fact that EndAccountSession is not able to fulfill its intended purpose - to end the session.  If a session never existed, then it would not be possible to perform the requested action.  Therefore, an exception is appropriate. To help illustrate how to handle this situation, I've modified the following code in Program.cs in the LinqToTwitterDemo project to illustrate the situation: static void EndSession(ITwitterAuthorizer auth) { using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/")) { try { //Log twitterCtx.Log = Console.Out; var status = twitterCtx.EndAccountSession(); Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } catch (TwitterQueryException tqe) { var webEx = tqe.InnerException as WebException; if (webEx != null) { var webResp = webEx.Response as HttpWebResponse; if (webResp != null && webResp.StatusCode == HttpStatusCode.Unauthorized) Console.WriteLine("Twitter didn't recognize you as having been logged in. Therefore, your request to end session is illogical.\n"); } var status = tqe.Response; Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } } } As expected, LINQ to Twitter wraps the exception in a TwitterQueryException as the InnerException.  The TwitterQueryException serves a very useful purpose through it's Response property.  Notice in the example above that the response has Request and Error proprieties.  These properties correspond to the information that Twitter returns as part of it's response payload.  This is often useful while debugging to help you understand why Twitter was unable to perform the  requested action.  Other times, it's cryptic, but that's another story.  At least you have some way of knowing in your code how to anticipate and handle these situations, along with having extra information to debug with. To sum things up, there are two points to make: when and why an exception should be raised and when to wrap and re-throw an exception in a custom exception type. I felt it was necessary to allow the exception to be raised because the called method was unable to perform the task it was designed for.  I also felt that it is inappropriate for a general library to do anything with exceptions because that could potentially hide a problem from the caller.  A related point is that it should be the exclusive decision of the application that uses the library on what to do with an exception.  Another aspect of this situation is that I wrapped the exception in a custom exception and re-threw.  This is a tough call because I don’t want to hide any stack trace information.  However, the need to make the exception more meaningful by including vital information returned from Twitter swayed me in the direction to design an interface that was as helpful as possible to library consumers.  As shown in the code above, you can dig into the exception and pull out a lot of good information, such as the fact that the underlying HTTP response was a 401 Unauthorized.  In all, trade-offs are seldom perfect for all cases, but combining the fact that the method was unable to perform its intended function, this is a library, and the extra information can be more helpful, it seemed to be the better design. @JoeMayo

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• Calculating for leap year [migrated]

  - by Bradley Bauer

  I've written this program using Java in Eclipse. I was able to utilize a formula I found that I explained in the commented out section. Using the for loop I can iterate through each month of the year, which I feel good about in that code, it seems clean and smooth to me. Maybe I could give the variables full names to make everything more readable but I'm just using the formula in its basic essence :) Well my problem is it doesn't calculate correctly for years like 2008... Leap Years. I know that if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) then we have a leap year. Maybe if the year is a leap year I need to subtract a certain amount of days from a certain month. Any solutions, or some direction would be great thanks :) package exercises; public class E28 { /* * Display the first days of each month * Enter the year * Enter first day of the year * * h = (q + (26 * (m + 1)) / 10 + k + k/4 + j/4 + 5j) % 7 * * h is the day of the week (0: Saturday, 1: Sunday ......) * q is the day of the month * m is the month (3: March 4: April.... January and Feburary are 13 and 14) * j is the century (year / 100) * k is the year of the century (year %100) * */ public static void main(String[] args) { java.util.Scanner input = new java.util.Scanner(System.in); System.out.print("Enter the year: "); int year = input.nextInt(); int j = year / 100; // Find century for formula int k = year % 100; // Find year of century for formula // Loop iterates 12 times. Guess why. for (int i = 1, m = i; i <= 12; i++) { // Make m = i. So loop processes formula once for each month if (m == 1 || m == 2) m += 12; // Formula requires that Jan and Feb are represented as 13 and 14 else m = i; // if not jan or feb, then set m to i int h = (1 + (26 * (m + 1)) / 10 + k + k/4 + j/4 + 5 * j) % 7; // Formula created by a really smart man somewhere // I let the control variable i steer the direction of the formual's m value String day; if (h == 0) day = "Saturday"; else if (h == 1) day = "Sunday"; else if (h == 2) day = "Monday"; else if (h == 3) day = "Tuesday"; else if (h == 4) day = "Wednesday"; else if (h == 5) day = "Thursday"; else day = "Friday"; switch (m) { case 13: System.out.println("January 1, " + year + " is " + day); break; case 14: System.out.println("Feburary 1, " + year + " is " + day); break; case 3: System.out.println("March 1, " + year + " is " + day); break; case 4: System.out.println("April 1, " + year + " is " + day); break; case 5: System.out.println("May 1, " + year + " is " + day); break; case 6: System.out.println("June 1, " + year + " is " + day); break; case 7: System.out.println("July 1, " + year + " is " + day); break; case 8: System.out.println("August 1, " + year + " is " + day); break; case 9: System.out.println("September 1, " + year + " is " + day); break; case 10: System.out.println("October 1, " + year + " is " + day); break; case 11: System.out.println("November 1, " + year + " is " + day); break; case 12: System.out.println("December 1, " + year + " is " + day); break; } } } }

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• Asynchrony in C# 5 (Part I)

  - by javarg

  I’ve been playing around with the new Async CTP preview available for download from Microsoft. It’s amazing how language trends are influencing the evolution of Microsoft’s developing platform. Much effort is being done at language level today than previous versions of .NET. In these post series I’ll review some major features contained in this release: Asynchronous functions TPL Dataflow Task based asynchronous Pattern Part I: Asynchronous Functions This is a mean of expressing asynchronous operations. This kind of functions must return void or Task/Task<> (functions returning void let us implement Fire & Forget asynchronous operations). The two new keywords introduced are async and await. async: marks a function as asynchronous, indicating that some part of its execution may take place some time later (after the method call has returned). Thus, all async functions must include some kind of asynchronous operations. This keyword on its own does not make a function asynchronous thought, its nature depends on its implementation. await: allows us to define operations inside a function that will be awaited for continuation (more on this later). Async function sample: Async/Await Sample async void ShowDateTimeAsync() {     while (true)     {         var client = new ServiceReference1.Service1Client();         var dt = await client.GetDateTimeTaskAsync();         Console.WriteLine("Current DateTime is: {0}", dt);         await TaskEx.Delay(1000);     } } The previous sample is a typical usage scenario for these new features. Suppose we query some external Web Service to get data (in this case the current DateTime) and we do so at regular intervals in order to refresh user’s UI. Note the async and await functions working together. The ShowDateTimeAsync method indicate its asynchronous nature to the caller using the keyword async (that it may complete after returning control to its caller). The await keyword indicates the flow control of the method will continue executing asynchronously after client.GetDateTimeTaskAsync returns. The latter is the most important thing to understand about the behavior of this method and how this actually works. The flow control of the method will be reconstructed after any asynchronous operation completes (specified with the keyword await). This reconstruction of flow control is the real magic behind the scene and it is done by C#/VB compilers. Note how we didn’t use any of the regular existing async patterns and we’ve defined the method very much like a synchronous one. Now, compare the following code snippet  in contrast to the previuous async/await: Traditional UI Async void ComplicatedShowDateTime() {     var client = new ServiceReference1.Service1Client();     client.GetDateTimeCompleted += (s, e) =>     {         Console.WriteLine("Current DateTime is: {0}", e.Result);         client.GetDateTimeAsync();     };     client.GetDateTimeAsync(); } The previous implementation is somehow similar to the first shown, but more complicated. Note how the while loop is implemented as a chained callback to the same method (client.GetDateTimeAsync) inside the event handler (please, do not do this in your own application, this is just an example).  How it works? Using an state workflow (or jump table actually), the compiler expands our code and create the necessary steps to execute it, resuming pending operations after any asynchronous one. The intention of the new Async/Await pattern is to let us think and code as we normally do when designing and algorithm. It also allows us to preserve the logical flow control of the program (without using any tricky coding patterns to accomplish this). The compiler will then create the necessary workflow to execute operations as the happen in time.

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• Taking HRMS to the Cloud to Simplify Human Resources Management

  - by HCM-Oracle

  By Anke Mogannam With human capital management (HCM) a top-of-mind issue for executives in every industry, human resources (HR) organizations are poised to have their day in the sun—proving not just their administrative worth but their strategic value as well.  To make good on that promise, however, HR must modernize. Indeed, if HR is to act as an agent of change—providing the swift reallocation of employees  and the rapid absorption of employee data required for enterprises to shift course on a dime—it must first deal with the disruptive change at its own front door. And increasingly, that means choosing the right technology and human resources management system (HRMS) for managing the entire employee lifecycle. Unfortunately, for most organizations, this task has proved easier said than done. This is because while much has been written about advances in HRMS technology, until recently, most of those advances took the form of disparate on-premises solutions designed to serve very specific purposes. Although this may have resulted in key competencies in certain areas, it also meant that processes for core HR functions like payroll and benefits were being carried out in separate systems from those used for talent management, workforce optimization, training, and so on. With no integration—and no single system of record—processes were disconnected, ease of use was impeded, user experience was diminished, and vital data was left untapped.  Today, however, that scenario has begun to change, and end-to-end cloud-based HCM solutions have moved from wished-for innovations to real-life solutions. Why, then, have HR organizations been so slow in adopting them? The answer—it would seem—is, “It’s complicated.” So complicated, in fact, that 45 percent of the respondents to PwC’s “Annual HR Technology Survey” (for 2013) reported having no formal HR software roadmap, and 40 percent stated that they “did not know” whether their organizations would be increasing their use of cloud or software as a service (SaaS) for HR.  Clearly, HR organizations need help sorting through the morass of HR software options confronting them. But just as clearly, there’s an enormous opportunity awaiting those that do. The trick will come in charting a course that allows HR to leverage existing technology while investing in the cloud-based solutions that will deliver the end-to-end processes, easy-to-understand analytics, and superior adaptability required to simplify—and add value to—every aspect of employee management. The Opportunity therefore is to cut costs, drive Innovation, and increase engagement by moving to cloud-based HCM.  Then you will benefit from one Interface, leverage many access points, and  gain at-a-glance insight across your entire workforce. With many legacy on-premises HR systems not being efficient anymore and cloud-based, integrated systems that span the range of HR functions finally reaching maturity, the time is ripe for moving core HR to the cloud. Indeed, for the first time ever there are more HRMS replacement initiatives than HRMS upgrade initiatives under way, and the majority of them involve moving to the cloud per Cedar Crestone’s 2013-2014 HRMS survey. To learn how you can launch your own cloud HCM initiative and begin using HR to power the enterprise, visit Oracle HRMS in the Cloud and Oracle’s new customer 2 cloud program. Anke Mogannam brings more than 16 years of marketing and human capital management experience in the technology industries to her role at Oracle where she is part of the Human Capital Management applications marketing team. In that role, Anke drives content marketing, messaging, go-to-market activities, integrated marketing campaigns, and field enablement. Prior to joining Oracle, Anke held several roles in communications, marketing, HCM product strategy and product management at PeopleSoft, SAP, Workday and Saba. Follow her on Twitter @amogannam

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• Mobile Deals: the Consumer Wants You in Their Pocket

  - by Mike Stiles

  Mobile deals offer something we talk about a lot in social marketing, relevant content. If a consumer is already predisposed to liking your product and gets a timely deal for it that’s easy and convenient to use, not only do you score on the marketing side, it clearly generates some of that precious ROI that’s being demanded of social. First, a quick gut-check on the public’s adoption of mobile. Nielsen figures have 55.5% of US mobile owners using smartphones. If young people are indeed the future, you can count on the move to mobile exploding exponentially. Teens are the fastest growing segment of smartphone users, and 58% of them have one. But the largest demographic of smartphone users is 25-34 at 74%. That tells you a focus on mobile will yield great results now, and even better results straight ahead. So we can tell both from statistics and from all the faces around you that are buried in their smartphones this is where consumers are. But are they looking at you? Do you have a valid reason why they should? Everybody likes a good deal. BIA/Kelsey says US consumers will spend $3.6 billion this year for daily deals (the Groupons and LivingSocials of the world), up 87% from 2011. The report goes on to say over 26% of small businesses are either "very likely" or "extremely likely" to offer up a deal in the next 6 months. Retail Gazette reports 58% of consumers shop with coupons, a 40% increase in 4 years. When you consider that a deal can be the impetus for a real-world transaction, a first-time visit to a store, an online purchase, entry into a loyalty program, a social referral, a new fan or follower, etc., that 26% figure shows us there’s a lot of opportunity being left on the table by brands. The existing and emerging technologies behind mobile devices make the benefits of offering deals listed above possible. Take how mobile payment systems are being tied into deal delivery and loyalty programs. If it’s really easy to use a coupon or deal, it’ll get used. If it’s complicated, it’ll be passed over as “not worth it.” When you can pay with your mobile via technologies that connects store and user, you get the deal, you get the loyalty credit, you pay, and your receipt is uploaded, all in one easy swipe. Nothing to keep track of, nothing to lose or forget about. And the store “knows” you, so future offers will be based on your tastes. Consider the endgame. A customer who’s a fan of your belt buckle store’s Facebook Page is in one of your physical retail locations. They pull up your app, because they’ve gotten used to a loyalty deal being offered when they go to your store. Voila. A 10% discount active for the next 30 minutes. Maybe the app also surfaces social references to your brand made by friends so they can check out a buckle someone’s raving about. If they aren’t a fan of your Page or don’t have your app, perhaps they’ve opted into location-based deal services so you can still get them that 10% deal while they’re in the store. Or maybe they’ve walked in with a pre-purchased Groupon or Living Social voucher. They pay with one swipe, and you’ve learned about their buying preferences, credited their loyalty account and can encourage them to share a pic of their new buckle on social. Happy customer. Happy belt buckle company. All because the brand was willing to use the tech that’s available to meet consumers where they are, incentivize them, and show them how much they’re valued through rewards.

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• Antenna Aligner Part 7: Connecting the dots

  - by Chris George

  The app is basically ready, so I eagerly started to sort out creating the application entry in iTunes Connect. It's mostly intuitive actually, although I did have to create yet another icon for iTunes sized 512x512 pixels, damn lucky I did the original graphics as vector! It took me longer to write the application description than anything else, I'm so not a tech author! I didn't like the way you have to 'make up' an SKU (Stock Keeping Unit) number. I have to do some googling to find out that it really doesn't matter what it is! It should be more obvious what to do from the actual website itself. That aside, the rest of it was actually fairly straightforward. As well as the details of the application, iPhone and iPad screenshots were also required. This posed somewhat of a problem. The iPhone ones were easy (as I have one!), but I do not (yet) own an iPad . So I thought I'd leave the iPad screenshots out for now. Once the application details were sorted, I moved onto the rights and pricing. At the start of the project I had made the decision that I wouldn't charge any more than the lowest amount £0.59. I believe there is a market for this, but as my first foray into app development I didn't want to take the mick. I did realise, however, that I had built my app with a developer certificate and provisioning profile. This was fairly quickly corrected, and again Nomad made this very easy to switch over to the distribution certificate and provisioning profile. With a sense of excitement I cracked open iTunes connect and clicked the upload button ... ...slight snag... . when the Nomad project was started, Apple allowed uploads of these binaries via iTunes Connect. But this is no longer possible, the only upload path is via the Application Loader available from the Apple Developer program. This itself has one limitation, it only runs on a mac! D'OH!!!  Actually my language was somewhat more colourful when this fact came to light. After picking my laptop up off the floor and putting it back together... ok only joking, but I did nearly throw it out of frustration!... I started to consider the options; I briefly entertained the idea of buying a cheap mac from ebay... no, that defeats the whole object of what I'm doing, plus my wife wouldn't be impressed there are some guys out there in the interweb who will upload your app for a small fee...but I don't really like the idea of giving some faceless email address my apple developer login details, as well as my app binary! find some willing friend with a mac who would kindly let me use it... obviously this is the only sensible option. In the meantime, I informed the Nomad team about this slight 'issue' and they are currently investigating possible solutions...

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• Recieving and organizing results without server side script (JavaScript)

  - by Aaron

  I have been working on a very large form project for the past few days. I finally managed to get tables to work properly within a javascript file that opens a new display window. Now the issue at hand is that I can't seem to get CSS code to work within the javascript that I have created. Before everyone starts thinking "just use server side script idiot" I have a few conditions and info about the file: The file is only being ran local due to confidential information risks. Once again no option for server access. The intranet the computers are on are already top security and this wouldn't exactly be a company wide program The code below is obviously just a demo with a simple form... The real file has six pages of highly confidential information Only certain fields on this form will actually be gathered (example: address doesnt appear in the results) The display page will contain data compiled into tables for easier viewing I need to be able to create css commands to easily detect certain information if it applies and along with matching design of the original form Here is the code: <html> <head> <title>Form Example</title> <script LANGUAGE="JavaScript" type="text/javascript"> function display() { DispWin = window.open('','NewWin', 'toolbar=no,status=no,width=800,height=600') message = "<body>"; message += "<table border=1 width=100%>"; message += "<tr>"; message += "<th colspan=2 align=center><font face=stencil color=black><h1>Results</h1><h4>one</h4></font>"; message += "</th>"; message += "</tr>"; message += "<td width=50% align=left>"; message += "<ul><li><b><font face=calibri color=red>NAME:</font></b> " + document.form1.yourname.value + "</UL>" message += "</td>"; message += "<td width=50% align=left>"; message += "<li><b>PHONE: </b>" + document.form1.phone.value + "</ul>"; message += "</td>"; message += "</table>"; message += "<body>"; DispWin.document.write(message); DispWin.document.body.style.cssText = 'color:#blue;'; } </script> </head> <body> <h1>Form Example</h1> Enter the following information: <form name="form1"> <p><b>Name:</b> <input TYPE="TEXT" SIZE="20" NAME="yourname"> </p> <p><b>Address:</b> <input TYPE="TEXT" SIZE="30" NAME="address"> </p> <p><b>Phone: </b> <input TYPE="TEXT" SIZE="15" NAME="phone"> </p> <p><input TYPE="BUTTON" VALUE="Display" onClick="display();"></p> </form> </body> </html> >

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• std::vector::size with glDrawElements crashes?

  - by NoobScratcher

  ( win32 / OpenGL 3.3 / GLSL 330 ) I decided after a long time of trying to do a graphical user interface using just opengl graphics to go back to a gui toolkit and so in the process have had to port alot of my code to win32. But I have a problem with my glDrawElement function. my program compiles and runs fine until it gets to glDrawElements then crashes.. which is rather annoying right. so I was trying to figure out why and I found out its std::vector::size member not returning the correct amount of faces in the unsigned interger vector eg, "vector<unsigned int>faces; " so when I use cout << faces.size() << endl; I got 68 elements???? instead of 24 as you can see here in this .obj file: # Blender v2.61 (sub 0) OBJ File: '' # www.blender.org v 1.000000 -1.000000 -1.000000 v 1.000000 -1.000000 1.000000 v -1.000000 -1.000000 1.000000 v -1.000000 -1.000000 -1.000000 v 1.000000 1.000000 -0.999999 v 0.999999 1.000000 1.000001 v -1.000000 1.000000 1.000000 v -1.000000 1.000000 -1.000000 s off f 1 2 3 4 f 5 8 7 6 f 1 5 6 2 f 2 6 7 3 <--- 24 Faces not 68? f 3 7 8 4 f 5 1 4 8 I'm using a parser I created to get the faces/vertexes in my .obj file: char modelbuffer [20000]; int MAX_BUFF = 20000; unsigned int face[3]; FILE * pfile; pfile = fopen(szFileName, "rw"); while(fgets(modelbuffer, MAX_BUFF, pfile) != NULL) { if('v') { Point p; sscanf(modelbuffer, "v %f %f %f", &p.x, &p.y, &p.z); points.push_back(p); cout << " p.x = " << p.x << " p.y = " << p.y << " p.z = " << p.x << endl; } if('f') { sscanf(modelbuffer, "f %d %d %d %d", &face[0], &face[1], &face[2], &face[3]); cout << "face[0] = " << face[0] << " face[1] = " << face[1] << " face[2] = " << face[2] << " face[3] = " << face[3] << "\n"; faces.push_back(face[0] - 1); faces.push_back(face[1] - 1); faces.push_back(face[2] - 1); faces.push_back(face[3] - 1); cout << face[0] - 1 << face[1] - 1 << face[2] - 1 << face[3] - 1 << endl; } } using this struct to store the x,y,z positions also this vector was used with Point: vector<Point>points; struct Point { float x, y, z; }; If someone could tell me why its not working and how to fix it that would be awesome I also provide a pastebin to the full source code if you want a closer look. http://pastebin.com/gznYLVw7

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• Bumblebee [ERROR]Cannot access secondary GPU - error: [XORG]

  - by Lunchbox

  Though this may seem like a duplicate question, none of the suggestions I've seen have worked for me, however nearly all posters get good results. I'll start with hardware: Metabox W350ST notebook Intel Core i7 4700 16GB RAM GTX 765M (with Optimus) 128GB SSD 1TB SSHD My initial error output when trying to optirun a game is: [ERROR]Cannot access secondary GPU - error: [XORG] (EE) NVIDIA(0): Failed to initialize the NVIDIA GPU at PCI:1:0:0. Please [133.973920] [ERROR]Aborting because fallback start is disabled. If anything else is needed to troubleshoot this just let me know. Adding bumblebee.conf: # Configuration file for Bumblebee. Values should **not** be put between quotes ## Server options. Any change made in this section will need a server restart # to take effect. [bumblebeed] # The secondary Xorg server DISPLAY number VirtualDisplay=:8 # Should the unused Xorg server be kept running? Set this to true if waiting # for X to be ready is too long and don't need power management at all. KeepUnusedXServer=false # The name of the Bumbleblee server group name (GID name) ServerGroup=bumblebee # Card power state at exit. Set to false if the card shoud be ON when Bumblebee # server exits. TurnCardOffAtExit=false # The default behavior of '-f' option on optirun. If set to "true", '-f' will # be ignored. NoEcoModeOverride=false # The Driver used by Bumblebee server. If this value is not set (or empty), # auto-detection is performed. The available drivers are nvidia and nouveau # (See also the driver-specific sections below) Driver=nvidia # Directory with a dummy config file to pass as a -configdir to secondary X XorgConfDir=/etc/bumblebee/xorg.conf.d ## Client options. Will take effect on the next optirun executed. [optirun] # Acceleration/ rendering bridge, possible values are auto, virtualgl and # primus. Bridge=auto # The method used for VirtualGL to transport frames between X servers. # Possible values are proxy, jpeg, rgb, xv and yuv. VGLTransport=proxy # List of paths which are searched for the primus libGL.so.1 when using # the primus bridge PrimusLibraryPath=/usr/lib/x86_64-linux-gnu/primus:/usr/lib/i386-linux-gnu/primus # Should the program run under optirun even if Bumblebee server or nvidia card # is not available? AllowFallbackToIGC=false # Driver-specific settings are grouped under [driver-NAME]. The sections are # parsed if the Driver setting in [bumblebeed] is set to NAME (or if auto- # detection resolves to NAME). # PMMethod: method to use for saving power by disabling the nvidia card, valid # values are: auto - automatically detect which PM method to use # bbswitch - new in BB 3, recommended if available # switcheroo - vga_switcheroo method, use at your own risk # none - disable PM completely # https://github.com/Bumblebee-Project/Bumblebee/wiki/Comparison-of-PM-methods ## Section with nvidia driver specific options, only parsed if Driver=nvidia [driver-nvidia] # Module name to load, defaults to Driver if empty or unset KernelDriver=nvidia PMMethod=auto # colon-separated path to the nvidia libraries LibraryPath=/usr/lib/nvidia-current:/usr/lib32/nvidia-current # comma-separated path of the directory containing nvidia_drv.so and the # default Xorg modules path XorgModulePath=/usr/lib/nvidia-current/xorg,/usr/lib/xorg/modules XorgConfFile=/etc/bumblebee/xorg.conf.nvidia ## Section with nouveau driver specific options, only parsed if Driver=nouveau [driver-nouveau] KernelDriver=nouveau PMMethod=auto XorgConfFile=/etc/bumblebee/xorg.conf.nouveau DRIVER VERSION - Output of jockey-text -l: nvidia_304_updates - nvidia_304_updates (Proprietary, Enabled, Not in use)

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• Library order is important

  - by Darryl Gove

  I've written quite extensively about link ordering issues, but I've not discussed the interaction between archive libraries and shared libraries. So let's take a simple program that calls a maths library function: #include <math.h int main() { for (int i=0; i<10000000; i++) { sin(i); } } We compile and run it to get the following performance: bash-3.2$ cc -g -O fp.c -lm bash-3.2$ timex ./a.out real 6.06 user 6.04 sys 0.01 Now most people will have heard of the optimised maths library which is added by the flag -xlibmopt. This contains optimised versions of key mathematical functions, in this instance, using the library doubles performance: bash-3.2$ cc -g -O -xlibmopt fp.c -lm bash-3.2$ timex ./a.out real 2.70 user 2.69 sys 0.00 The optimised maths library is provided as an archive library (libmopt.a), and the driver adds it to the link line just before the maths library - this causes the linker to pick the definitions provided by the static library in preference to those provided by libm. We can see the processing by asking the compiler to print out the link line: bash-3.2$ cc -### -g -O -xlibmopt fp.c -lm /usr/ccs/bin/ld ... fp.o -lmopt -lm -o a.out... The flag to the linker is -lmopt, and this is placed before the -lm flag. So what happens when the -lm flag is in the wrong place on the command line: bash-3.2$ cc -g -O -xlibmopt -lm fp.c bash-3.2$ timex ./a.out real 6.02 user 6.01 sys 0.01 If the -lm flag is before the source file (or object file for that matter), we get the slower performance from the system maths library. Why's that? If we look at the link line we can see the following ordering: /usr/ccs/bin/ld ... -lmopt -lm fp.o -o a.out So the optimised maths library is still placed before the system maths library, but the object file is placed afterwards. This would be ok if the optimised maths library were a shared library, but it is not - instead it's an archive library, and archive library processing is different - as described in the linker and library guide: "The link-editor searches an archive only to resolve undefined or tentative external references that have previously been encountered." An archive library can only be used resolve symbols that are outstanding at that point in the link processing. When fp.o is placed before the libmopt.a archive library, then the linker has an unresolved symbol defined in fp.o, and it will search the archive library to resolve that symbol. If the archive library is placed before fp.o then there are no unresolved symbols at that point, and so the linker doesn't need to use the archive library. This is why libmopt needs to be placed after the object files on the link line. On the other hand if the linker has observed any shared libraries, then at any point these are checked for any unresolved symbols. The consequence of this is that once the linker "sees" libm it will resolve any symbols it can to that library, and it will not check the archive library to resolve them. This is why libmopt needs to be placed before libm on the link line. This leads to the following order for placing files on the link line: Object files Archive libraries Shared libraries If you use this order, then things will consistently get resolved to the archive libraries rather than to the shared libaries.

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• trying to setup wireless

  - by JohnMerlino

  I'm trying to set up wireless on vostro 1520 dell laptop, with latest Ubuntu install. Here's the output of some of the commands that I was told to run: lshw -C network viggy@ubuntu:~$ lshw -C network WARNING: you should run this program as super-user. *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:08:00.0 logical name: eth0 version: 03 serial: 00:24:e8:da:84:25 size: 100Mbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: bus_master cap_list rom ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168d-1.fw ip=192.168.2.6 latency=0 multicast=yes port=MII speed=100Mbit/s resources: irq:47 ioport:3000(size=256) memory:f6004000-f6004fff memory:f6000000-f6003fff memory:f6020000-f603ffff *-network description: Network controller product: BCM4312 802.11b/g LP-PHY vendor: Broadcom Corporation physical id: 0 bus info: pci@0000:0e:00.0 version: 01 width: 64 bits clock: 33MHz capabilities: bus_master cap_list configuration: driver=b43-pci-bridge latency=0 resources: irq:18 memory:fa000000-fa003fff *-network DISABLED description: Wireless interface physical id: 1 logical name: wlan0 serial: 0c:60:76:05:ee:74 capabilities: ethernet physical wireless configuration: broadcast=yes driver=b43 driverversion=3.2.0-29-generic firmware=N/A multicast=yes wireless=IEEE 802.11bg lspci 00:00.0 Host bridge: Intel Corporation Mobile 4 Series Chipset Memory Controller Hub (rev 07) 00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) 00:02.1 Display controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07) 00:1a.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 (rev 03) 00:1a.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 (rev 03) 00:1a.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 (rev 03) 00:1a.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 (rev 03) 00:1b.0 Audio device: Intel Corporation 82801I (ICH9 Family) HD Audio Controller (rev 03) 00:1c.0 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 1 (rev 03) 00:1c.1 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 2 (rev 03) 00:1c.2 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 3 (rev 03) 00:1c.3 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 4 (rev 03) 00:1c.4 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 5 (rev 03) 00:1c.5 PCI bridge: Intel Corporation 82801I (ICH9 Family) PCI Express Port 6 (rev 03) 00:1d.0 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 (rev 03) 00:1d.1 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 (rev 03) 00:1d.2 USB controller: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 (rev 03) 00:1d.7 USB controller: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 (rev 03) 00:1e.0 PCI bridge: Intel Corporation 82801 Mobile PCI Bridge (rev 93) 00:1f.0 ISA bridge: Intel Corporation ICH9M LPC Interface Controller (rev 03) 00:1f.2 SATA controller: Intel Corporation 82801IBM/IEM (ICH9M/ICH9M-E) 4 port SATA Controller [AHCI mode] (rev 03) 00:1f.3 SMBus: Intel Corporation 82801I (ICH9 Family) SMBus Controller (rev 03) 08:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 03) 0e:00.0 Network controller: Broadcom Corporation BCM4312 802.11b/g LP-PHY (rev 01) 1a:00.0 FireWire (IEEE 1394): O2 Micro, Inc. Device 10f7 (rev 01) 1a:00.1 SD Host controller: O2 Micro, Inc. Device 8120 (rev 01) 1a:00.2 Mass storage controller: O2 Micro, Inc. Device 8130 (rev 01) iwconfig lo no wireless extensions. wlan0 IEEE 802.11bg ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=0 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:on eth0 no wireless extensions. At this point in time, I don't have wireless.

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• Omni-directional light shadow mapping with cubemaps in WebGL

  - by Winged

  First of all I must say, that I have read a lot of posts describing an usage of cubemaps, but I'm still confused about how to use them. My goal is to achieve a simple omni-directional (point) light type shading in my WebGL application. I know that there is a lot more techniques (like using Two-Hemispheres or Camera Space Shadow Mapping) which are way more efficient, but for an educational purpose cubemaps are my primary goal. Till now, I have adapted a simple shadow mapping which works with spotlights (with one exception: I don't know how to cut off the glitchy part beyond the reach of a single shadow map texture): glitchy shadow mapping<<< So for now, this is how I understand the usage of cubemaps in shadow mapping: Setup a framebuffer (in case of cubemaps - 6 framebuffers; 6 instead of 1 because every usage of framebufferTexture2D slows down an execution which is nicely described here <<<) and a texture cubemap. Also in WebGL depth components are not well supported, so I need to render it to RGBA first. this.texture = gl.createTexture(); gl.bindTexture(gl.TEXTURE_CUBE_MAP, this.texture); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR); gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MAG_FILTER, gl.LINEAR); for (var face = 0; face < 6; face++) gl.texImage2D(gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, 0, gl.RGBA, this.size, this.size, 0, gl.RGBA, gl.UNSIGNED_BYTE, null); gl.bindTexture(gl.TEXTURE_CUBE_MAP, null); this.framebuffer = []; for (face = 0; face < 6; face++) { this.framebuffer[face] = gl.createFramebuffer(); gl.bindFramebuffer(gl.FRAMEBUFFER, this.framebuffer[face]); gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_CUBE_MAP_POSITIVE_X + face, this.texture, 0); gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, this.depthbuffer); var e = gl.checkFramebufferStatus(gl.FRAMEBUFFER); // Check for errors if (e !== gl.FRAMEBUFFER_COMPLETE) throw "Cubemap framebuffer object is incomplete: " + e.toString(); } Setup the light and the camera (I'm not sure if should I store all of 6 view matrices and send them to shaders later, or is there a way to do it with just one view matrix). Render the scene 6 times from the light's position, each time in another direction (X, -X, Y, -Y, Z, -Z) for (var face = 0; face < 6; face++) { gl.bindFramebuffer(gl.FRAMEBUFFER, shadow.buffer.framebuffer[face]); gl.viewport(0, 0, shadow.buffer.size, shadow.buffer.size); gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); camera.lookAt( light.position.add( cubeMapDirections[face] ) ); scene.draw(shadow.program); } In a second pass, calculate the projection a a current vertex using light's projection and view matrix. Now I don't know If should I calculate 6 of them, because of 6 faces of a cubemap. ScaleMatrix pushes the projected vertex into the 0.0 - 1.0 region. vDepthPosition = ScaleMatrix * uPMatrixFromLight * uVMatrixFromLight * vWorldVertex; In a fragment shader calculate the distance between the current vertex and the light position and check if it's deeper then the depth information read from earlier rendered shadow map. I know how to do it with a 2D Texture, but I have no idea how should I use cubemap texture here. I have read that texture lookups into cubemaps are performed by a normal vector instead of a UV coordinate. What vector should I use? Just a normalized vector pointing to the current vertex? For now, my code for this part looks like this (not working yet): float shadow = 1.0; vec3 depth = vDepthPosition.xyz / vDepthPosition.w; depth.z = length(vWorldVertex.xyz - uLightPosition) * linearDepthConstant; float shadowDepth = unpack(textureCube(uDepthMapSampler, vWorldVertex.xyz)); if (depth.z > shadowDepth) shadow = 0.5; Could you give me some hints or examples (preferably in WebGL code) how I should build it?

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• Caching factory design

  - by max

  I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

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• 2D Tile based Game Collision problem

  - by iNbdy

  I've been trying to program a tile based game, and I'm stuck at the collision detection. Here is my code (not the best ^^): void checkTile(Character *c, int **map) { int x1,x2,y1,y2; /* Character position in the map */ c->upY = (c->y) / TILE_SIZE; // Top left corner c->downY = (c->y + c->h) / TILE_SIZE; // Bottom left corner c->leftX = (c->x) / TILE_SIZE; // Top right corner c->rightX = (c->x + c->w) / TILE_SIZE; // Bottom right corner x1 = (c->x + 10) / TILE_SIZE; // 10px from left side point x2 = (c->x + c->w - 10) / TILE_SIZE; // 10px from right side point y1 = (c->y + 10) / TILE_SIZE; // 10px from top side point y2 = (c->y + c->h - 10) / TILE_SIZE; // 10px from bottom side point /* Top */ if (map[c->upY][x1] > 2 || map[c->upY][x2] > 2) c->topCollision = 1; else c->topCollision = 0; /* Bottom */ if ((map[c->downY][x1] > 2 || map[c->downY][x2] > 2)) c->downCollision = 1; else c->downCollision = 0; /* Left */ if (map[y1][c->leftX] > 2 || map[y2][c->leftX] > 2) c->leftCollision = 1; else c->leftCollision = 0; /* Right */ if (map[y1][c->rightX] > 2 || map[y2][c->rightX] > 2) c->rightCollision = 1; else c->rightCollision = 0; } That calculates 8 collision points My moving function is like that: void movePlayer(Character *c, int **map) { if ((c->dirX == LEFT && !c->leftCollision) || (c->dirX == RIGHT && !c->rightCollision)) c->x += c->vx; if ((c->dirY == UP && !c->topCollision) || (c->dirY == DOWN && !c->downCollision)) c->y += c->vy; checkPosition(c, map); } and the checkPosition: void checkPosition(Character *c, int **map) { checkTile(c, map); if (c->downCollision) { if (c->state != JUMPING) { c->vy = 0; c->y = (c->downY * TILE_SIZE - c->h); } } if (c->leftCollision) { c->vx = 0; c->x = (c->leftX) * TILE_SIZE + TILE_SIZE; } if (c->rightCollision) { c->vx = 0; c->x = c->rightX * TILE_SIZE - c->w; } } This works, but sometimes, when the player is landing on ground, right and left collision points become equal to 1. So it's as if there were collision coming from left or right. Does anyone know why this is doing this?

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• Call for Papers for both Devoxx UK and France now open!

  - by Yolande

  Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} The two conferences are taking place the last week of March 2013 with London on March 26th and 27 and Paris on March 28th and 29th. Oracle fully supports "Devoxx UK" and "Devoxx France" as a European Platinum Partner. Submit proposals and participate in both conferences since they are a two-hour train ride away from one another. The Devoxx conferences are designed “for developers by developers.” The conference committees are looking for speakers who are passionate developers unafraid to share their knowledge of Java, mobile, web and beyond. The sessions are about frameworks, tools and development with in-depth conference sessions, short practical quickies, and bird-of-a-feather discussions. Those different formats allow speakers to choose the best way to present their topics and can be mentioned during the submission process Devoxx has proven its success under Stephan Janssen, organizer of Devoxx in Belgium for the past 11 years. Devoxx has been the biggest Java conference in Europe for many years. To organize those local conferences, Stephan has enrolled the top community leaders in the UK and France. Ben Evans and Martijn Verberg are the leaders of London Java User Group (JUG) and are also known internationally for starting the Adopt-a-JSR program. Antonio Goncalves is the leader of the Paris JUG. He organized last year’s Devoxx France, which was a big success with twice the size first expected. The organizers made sure to add the local character to the conferences. "The community energy has to feel right," said Ben Evans and for that he picked an "old Victoria hall" for the venue. Those leaders are part of very dynamic Java communities in France and in the UK. France has 22 JUGs; the Paris JUG alone has 2,000 members. The UK has over 50,000 developers working in London and its surroundings; a lot of them are Java developers working in the financial industry. The conference fee is kept as low as possible to encourage those developers to attend. Devoxx promises to be crowded and sold out in advance. Make sure to submit your talks to both Devoxx UK and France before January 31st, 2013. 

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• The battle between Java vs. C#

  The battle between Java vs. C# has been a big debate amongst the development community over the last few years. Both languages have specific pros and cons based on the needs of a particular project. In general both languages utilize a similar coding syntax that is based on C++, and offer developers similar functionality. This being said, the communities supporting each of these languages are very different. The divide amongst the communities is much like the political divide in America, where the Java community would represent the Democrats and the .Net community would represent the Republicans. The Democratic Party is a proponent of the working class and the general population. Currently, Java is deeply entrenched in the open source community that is distributed freely to anyone who has an interest in using it. Open source communities rely on developers to keep it alive by constantly contributing code to make applications better; essentially they develop code by the community. This is in stark contrast to the C# community that is typically a pay to play community meaning that you must pay for code that you want to use because it is developed as products to be marketed and sold for a profit. This ties back into my reference to the Republicans because they typically represent the needs of business and personal responsibility. This is emphasized by the belief that code is a commodity and that it can be sold for a profit which is in direct conflict to the laissez-faire beliefs of the open source community. Beyond the general differences between Java and C#, they also target two different environments. Java is developed to be environment independent and only requires that users have a Java virtual machine running in order for the java code to execute. C# on the other hand typically targets any system running a windows operating system and has the appropriate version of the .Net Framework installed. However, recently there has been push by a segment of the Open source community based around the Mono project that lets C# code run on other non-windows operating systems. In addition, another feature of C# is that it compiles into an intermediate language, and this is what is executed when the program runs. Because C# is reduced down to an intermediate language called Common Language Runtime (CLR) it can be combined with other languages that are also compiled in to the CLR like Visual Basic (VB) .Net, and F#. The allowance and interaction between multiple languages in the .Net Framework enables projects to utilize existing code bases regardless of the actual syntax because they can be compiled in to CLR and executed as one codebase. As a software engineer I personally feel that it is really important to learn as many languages as you can or at least be open to learn as many languages as you can because no one language will work in every situation.  In some cases Java may be a better choice for a project and others may be C#. It really depends on the requirements of a project and the time constraints. In addition, I feel that is really important to concentrate on understanding the logic of programming and be able to translate business requirements into technical requirements. If you can understand both programming logic and business requirements then deciding which language to use is just basically choosing what syntax to write for a given business problem or need. In regards to code refactoring and dynamic languages it really does not matter. Eventually all projects will be refactored or decommissioned to allow for progress. This is the way of life in the software development industry. The language of a project should not be chosen based on the fact that a project will eventually be refactored because they all will get refactored.

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• Best approach to depth streaming via existing codec

  - by Kevin

  I'm working on a development system (and game) intended for games set mostly in static third-person views. We produce our scenery by CG and photographic techniques. Our background art is rendered off-line by a production-grade renderer. To allow the runtime imagery to properly interact with the background art, I wrote a program to convert from depth output by Mental Ray into a texture, and a pixel shader to draw a quad such that the Z data comes from the texture. This technique is working out very well, but now we've decided that some of the camera angle changes between scenes should be animated. The animation itself is straightforward to produce from our CG models. We intend to encode it to some HD video codec such as H.264. The problem is that in order to maintain our runtime imagery on the screen, the depth buffer will need to be loaded for each video frame. Due to the bandwidth, the video's depth data will need to be compressed efficiently. I've looked into methods for performing temporal compression of depth info and found an interesting research paper here: http://web4.cs.ucl.ac.uk/staff/j.kautz/publications/depth-streaming.pdf The method establishes a mapping between 16-bit depth values and YCbCr values. The mapping is tuned to the properties of existing video codecs in order to maximize precision of the decoded depths after the YCbCr has undergone video compression. It allows an existing, unmodified video codec to be used on the backend. I'm looking at how to pull this off with the least possible work. (This design change was unplanned.) Our game engine itself is native C++, presently for Win32 and DirectX, although we've worked hard to keep platform dependence segregated because we intend other ports. We don't have motion video facilities in the engine yet but will ultimately need that anyway for cinematics. I was planning on using some off-the-shelf motion video solution we can plug into our engine, and haven't chosen one yet. This new added requirement makes selecting one harder since, among other things, we'll now need to bypass colourspace conversion on one of the streams, and also will need to be playing two streams simultaneously in lockstep, on top of in some cases audio on one of them (for the cinematics). I'm also wondering if it's possible (or even useful) to do the conversion from YCbCr to depth in a pixel shader, or if it's better to just do it in CPU and separately load the resulting depth values into a locked tex. The conversion unfortunately does involve branching logic per-pixel. (There are more naive mappings that don't need branching, but they produce inferior results.) It could be reduced to a table lookup but the table would be 32MB. Programming is second-nature to me but I'm not that experienced with pix shaders and have zero knowledge of off-the-shelf video solutions. I'd therefore be interested in advice from others who may have dealt more with depth streaming, pixel shaders, and/or off-the-shelf codecs, regarding how feasible the proposed application is and what off-the-shelf video systems out there would best get along with this usage case.

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• Passing data between the VirtualBox Host and the Guest

  - by Fat Bloke

  Here's a good question: "How can you figure out the VM name from within the VM itself?" While this data is not automatically available, the general purpose, and very powerful VirtualBox "GuestProperty" APIs can be used from the host and guest to pass arbitrary data, in key/value pairs format, in and out of the guest. Note that this does require that the VirtualBox Guest Additions have been installed in the guest. To play with this, try using the "VBoxManage" command line on your VirtualBox host machine, and "VBoxControl" in the guest. Host syntax VBoxManage guestproperty get <vmname>|<uuid> <property> [--verbose] VBoxManage guestproperty set <vmname>|<uuid> <property> [<value> [--flags <flags>]] VBoxManage guestproperty enumerate <vmname>|<uuid> [--patterns <patterns>] VBoxManage guestproperty wait <vmname>|<uuid> <patterns> [--timeout <msec>] [--fail-on-timeout]   Guest syntax VBoxControl.exe guestproperty        get <property> [-verbose] VBoxControl.exe guestproperty        set <property> [<value> [-flags <flags>]] VBoxControl.exe guestproperty        enumerate [-patterns <patterns>] VBoxControl.exe guestproperty        wait <patterns>                                      [-timestamp <last timestamp>]                                      [-timeout <timeout in ms>  So to solve our problem above, we set the vm name in the Host system on an arbitrary key like this: $ VBoxManage guestproperty set "Windows 7 (x64)" /MyData/VMname "Windows 7 (x64)" And within the guest we can use: C:\Program Files\Oracle\VirtualBox Guest Additions>VBoxControl.exe guestproperty get /MyData/VMname Oracle VM VirtualBox Guest Additions Command Line Management Interface Version 4.1.14 (C) 2008-2012 Oracle Corporation All rights reserved. Value: Windows 7 (x64) The GuestProperty API is pretty powerful, so for the interested, get more info in the User Manual. - FB 

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• Comparing Apples and Pairs

  - by Tony Davis

  A recent study, High Costs and Negative Value of Pair Programming, by Capers Jones, pulls no punches in its assessment of the costs-to- benefits ratio of pair programming, two programmers working together, at a single computer, rather than separately. He implies that pair programming is a method rushed into production on a wave of enthusiasm for Agile or Extreme Programming, without any real regard for its effectiveness. Despite admitting that his data represented a far from complete study of the economics of pair programming, his conclusions were stark: it was 2.5 times more expensive, resulted in a 15% drop in productivity, and offered no significant quality benefits. The author provides a more scientific analysis than Jon Evans’ Pair Programming Considered Harmful, but the theme is the same. In terms of upfront-coding costs, pair programming is surely more expensive. The claim of productivity loss is dubious and contested by other studies. The third claim, though, did surprise me. The author’s data suggests that if both the pair and the individual programmers employ static code analysis and testing, then there is no measurable difference in the resulting code quality, in terms of defects per function point. In other words, pair programming incurs a massive extra cost for no tangible return in investment. There were, inevitably, many criticisms of his data and his conclusions, a few of which are persuasive. Firstly, that the driver/observer model of pair programming, on which the study bases its findings, is far from the most effective. For example, many find Ping-Pong pairing, based on use of test-driven development, far more productive. Secondly, that it doesn’t distinguish between “expert” and “novice” pair programmers– that is, independently of other programming skills, how skilled was an individual at pair programming. Thirdly, that his measure of quality is too narrow. This point rings true, certainly at Red Gate, where developers don’t pair program all the time, but use the method in short bursts, while tackling a tricky problem and needing a fresh perspective on the best approach, or more in-depth knowledge in a particular domain. All of them argue that pair programming, and collective code ownership, offers significant rewards, if not in terms of immediate “bug reduction”, then in removing the likelihood of single points of failure, and improving the overall quality and longer-term adaptability/maintainability of the design. There is also a massive learning benefit for both participants. One developer told me how he once worked in the same team over consecutive summers, the first time with no pair programming and the second time pair-programming two-thirds of the time, and described the increased rate of learning the second time as “phenomenal”. There are a great many theories on how we should develop software (Scrum, XP, Lean, etc.), but woefully little scientific research in their effectiveness. For a group that spends so much time crunching other people’s data, I wonder if developers spend enough time crunching data about themselves. Capers Jones’ data may be incomplete, but should cause a pause for thought, especially for any large IT departments, supporting commerce and industry, who are considering pair programming. It certainly shouldn’t discourage teams from exploring new ways of developing software, as long as they also think about how to gather hard data to gauge their effectiveness.

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