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  • Anatomy of a .NET Assembly - PE Headers

    - by Simon Cooper
    Today, I'll be starting a look at what exactly is inside a .NET assembly - how the metadata and IL is stored, how Windows knows how to load it, and what all those bytes are actually doing. First of all, we need to understand the PE file format. PE files .NET assemblies are built on top of the PE (Portable Executable) file format that is used for all Windows executables and dlls, which itself is built on top of the MSDOS executable file format. The reason for this is that when .NET 1 was released, it wasn't a built-in part of the operating system like it is nowadays. Prior to Windows XP, .NET executables had to load like any other executable, had to execute native code to start the CLR to read & execute the rest of the file. However, starting with Windows XP, the operating system loader knows natively how to deal with .NET assemblies, rendering most of this legacy code & structure unnecessary. It still is part of the spec, and so is part of every .NET assembly. The result of this is that there are a lot of structure values in the assembly that simply aren't meaningful in a .NET assembly, as they refer to features that aren't needed. These are either set to zero or to certain pre-defined values, specified in the CLR spec. There are also several fields that specify the size of other datastructures in the file, which I will generally be glossing over in this initial post. Structure of a PE file Most of a PE file is split up into separate sections; each section stores different types of data. For instance, the .text section stores all the executable code; .rsrc stores unmanaged resources, .debug contains debugging information, and so on. Each section has a section header associated with it; this specifies whether the section is executable, read-only or read/write, whether it can be cached... When an exe or dll is loaded, each section can be mapped into a different location in memory as the OS loader sees fit. In order to reliably address a particular location within a file, most file offsets are specified using a Relative Virtual Address (RVA). This specifies the offset from the start of each section, rather than the offset within the executable file on disk, so the various sections can be moved around in memory without breaking anything. The mapping from RVA to file offset is done using the section headers, which specify the range of RVAs which are valid within that section. For example, if the .rsrc section header specifies that the base RVA is 0x4000, and the section starts at file offset 0xa00, then an RVA of 0x401d (offset 0x1d within the .rsrc section) corresponds to a file offset of 0xa1d. Because each section has its own base RVA, each valid RVA has a one-to-one mapping with a particular file offset. PE headers As I said above, most of the header information isn't relevant to .NET assemblies. To help show what's going on, I've created a diagram identifying all the various parts of the first 512 bytes of a .NET executable assembly. I've highlighted the relevant bytes that I will refer to in this post: Bear in mind that all numbers are stored in the assembly in little-endian format; the hex number 0x0123 will appear as 23 01 in the diagram. The first 64 bytes of every file is the DOS header. This starts with the magic number 'MZ' (0x4D, 0x5A in hex), identifying this file as an executable file of some sort (an .exe or .dll). Most of the rest of this header is zeroed out. The important part of this header is at offset 0x3C - this contains the file offset of the PE signature (0x80). Between the DOS header & PE signature is the DOS stub - this is a stub program that simply prints out 'This program cannot be run in DOS mode.\r\n' to the console. I will be having a closer look at this stub later on. The PE signature starts at offset 0x80, with the magic number 'PE\0\0' (0x50, 0x45, 0x00, 0x00), identifying this file as a PE executable, followed by the PE file header (also known as the COFF header). The relevant field in this header is in the last two bytes, and it specifies whether the file is an executable or a dll; bit 0x2000 is set for a dll. Next up is the PE standard fields, which start with a magic number of 0x010b for x86 and AnyCPU assemblies, and 0x20b for x64 assemblies. Most of the rest of the fields are to do with the CLR loader stub, which I will be covering in a later post. After the PE standard fields comes the NT-specific fields; again, most of these are not relevant for .NET assemblies. The one that is is the highlighted Subsystem field, and specifies if this is a GUI or console app - 0x20 for a GUI app, 0x30 for a console app. Data directories & section headers After the PE and COFF headers come the data directories; each directory specifies the RVA (first 4 bytes) and size (next 4 bytes) of various important parts of the executable. The only relevant ones are the 2nd (Import table), 13th (Import Address table), and 15th (CLI header). The Import and Import Address table are only used by the startup stub, so we will look at those later on. The 15th points to the CLI header, where the CLR-specific metadata begins. After the data directories comes the section headers; one for each section in the file. Each header starts with the section's ASCII name, null-padded to 8 bytes. Again, most of each header is irrelevant, but I've highlighted the base RVA and file offset in each header. In the diagram, you can see the following sections: .text: base RVA 0x2000, file offset 0x200 .rsrc: base RVA 0x4000, file offset 0xa00 .reloc: base RVA 0x6000, file offset 0x1000 The .text section contains all the CLR metadata and code, and so is by far the largest in .NET assemblies. The .rsrc section contains the data you see in the Details page in the right-click file properties page, but is otherwise unused. The .reloc section contains address relocations, which we will look at when we study the CLR startup stub. What about the CLR? As you can see, most of the first 512 bytes of an assembly are largely irrelevant to the CLR, and only a few bytes specify needed things like the bitness (AnyCPU/x86 or x64), whether this is an exe or dll, and the type of app this is. There are some bytes that I haven't covered that affect the layout of the file (eg. the file alignment, which determines where in a file each section can start). These values are pretty much constant in most .NET assemblies, and don't affect the CLR data directly. Conclusion To summarize, the important data in the first 512 bytes of a file is: DOS header. This contains a pointer to the PE signature. DOS stub, which we'll be looking at in a later post. PE signature PE file header (aka COFF header). This specifies whether the file is an exe or a dll. PE standard fields. This specifies whether the file is AnyCPU/32bit or 64bit. PE NT-specific fields. This specifies what type of app this is, if it is an app. Data directories. The 15th entry (at offset 0x168) contains the RVA and size of the CLI header inside the .text section. Section headers. These are used to map between RVA and file offset. The important one is .text, which is where all the CLR data is stored. In my next post, we'll start looking at the metadata used by the CLR directly, which is all inside the .text section.

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  • More Fun With Math

    - by PointsToShare
    More Fun with Math   The runaway student – three different ways of solving one problem Here is a problem I read in a Russian site: A student is running away. He is moving at 1 mph. Pursuing him are a lion, a tiger and his math teacher. The lion is 40 miles behind and moving at 6 mph. The tiger is 28 miles behind and moving at 4 mph. His math teacher is 30 miles behind and moving at 5 mph. Who will catch him first? Analysis Obviously we have a set of three problems. They are all basically the same, but the details are different. The problems are of the same class. Here is a little excursion into computer science. One of the things we strive to do is to create solutions for classes of problems rather than individual problems. In your daily routine, you call it re-usability. Not all classes of problems have such solutions. If a class has a general (re-usable) solution, it is called computable. Otherwise it is unsolvable. Within unsolvable classes, we may still solve individual (some but not all) problems, albeit with different approaches to each. Luckily the vast majority of our daily problems are computable, and the 3 problems of our runaway student belong to a computable class. So, let’s solve for the catch-up time by the math teacher, after all she is the most frightening. She might even make the poor runaway solve this very problem – perish the thought! Method 1 – numerical analysis. At 30 miles and 5 mph, it’ll take her 6 hours to come to where the student was to begin with. But by then the student has advanced by 6 miles. 6 miles require 6/5 hours, but by then the student advanced by another 6/5 of a mile as well. And so on and so forth. So what are we to do? One way is to write code and iterate it until we have solved it. But this is an infinite process so we’ll end up with an infinite loop. So what to do? We’ll use the principles of numerical analysis. Any calculator – your computer included – has a limited number of digits. A double floating point number is good for about 14 digits. Nothing can be computed at a greater accuracy than that. This means that we will not iterate ad infinidum, but rather to the point where 2 consecutive iterations yield the same result. When we do financial computations, we don’t even have to go that far. We stop at the 10th of a penny.  It behooves us here to stop at a 10th of a second (100 milliseconds) and this will how we will avoid an infinite loop. Interestingly this alludes to the Zeno paradoxes of motion – in particular “Achilles and the Tortoise”. Zeno says exactly the same. To catch the tortoise, Achilles must always first come to where the tortoise was, but the tortoise keeps moving – hence Achilles will never catch the tortoise and our math teacher (or lion, or tiger) will never catch the student, or the policeman the thief. Here is my resolution to the paradox. The distance and time in each step are smaller and smaller, so the student will be caught. The only thing that is infinite is the iterative solution. The race is a convergent geometric process so the steps are diminishing, but each step in the solution takes the same amount of effort and time so with an infinite number of steps, we’ll spend an eternity solving it.  This BTW is an original thought that I have never seen before. But I digress. Let’s simply write the code to solve the problem. To make sure that it runs everywhere, I’ll do it in JavaScript. function LongCatchUpTime(D, PV, FV) // D is Distance; PV is Pursuers Velocity; FV is Fugitive’ Velocity {     var t = 0;     var T = 0;     var d = parseFloat(D);     var pv = parseFloat (PV);     var fv = parseFloat (FV);     t = d / pv;     while (t > 0.000001) //a 10th of a second is 1/36,000 of an hour, I used 1/100,000     {         T = T + t;         d = t * fv;         t = d / pv;     }     return T;     } By and large, the higher the Pursuer’s velocity relative to the fugitive, the faster the calculation. Solving this with the 10th of a second limit yields: 7.499999232000001 Method 2 – Geometric Series. Each step in the iteration above is smaller than the next. As you saw, we stopped iterating when the last step was small enough, small enough not to really matter.  When we have a sequence of numbers in which the ratio of each number to its predecessor is fixed we call the sequence geometric. When we are looking at the sum of sequence, we call the sequence of sums series.  Now let’s look at our student and teacher. The teacher runs 5 times faster than the student, so with each iteration the distance between them shrinks to a fifth of what it was before. This is a fixed ratio so we deal with a geometric series.  We normally designate this ratio as q and when q is less than 1 (0 < q < 1) the sum of  + … +  is  – 1) / (q – 1). When q is less than 1, it is easier to use ) / (1 - q). Now, the steps are 6 hours then 6/5 hours then 6/5*5 and so on, so q = 1/5. And the whole series is multiplied by 6. Also because q is less than 1 , 1/  diminishes to 0. So the sum is just  / (1 - q). or 1/ (1 – 1/5) = 1 / (4/5) = 5/4. This times 6 yields 7.5 hours. We can now continue with some algebra and take it back to a simpler formula. This is arduous and I am not going to do it here. Instead let’s do some simpler algebra. Method 3 – Simple Algebra. If the time to capture the fugitive is T and the fugitive travels at 1 mph, then by the time the pursuer catches him he travelled additional T miles. Time is distance divided by speed, so…. (D + T)/V = T  thus D + T = VT  and D = VT – T = (V – 1)T  and T = D/(V – 1) This “strangely” coincides with the solution we just got from the geometric sequence. This is simpler ad faster. Here is the corresponding code. function ShortCatchUpTime(D, PV, FV) {     var d = parseFloat(D);     var pv = parseFloat (PV);     var fv = parseFloat (FV);     return d / (pv - fv); } The code above, for both the iterative solution and the algebraic solution are actually for a larger class of problems.  In our original problem the student’s velocity (speed) is 1 mph. In the code it may be anything as long as it is less than the pursuer’s velocity. As long as PV > FV, the pursuer will catch up. Here is the really general formula: T = D / (PV – FV) Finally, let’s run the program for each of the pursuers.  It could not be worse. I know he’d rather be eaten alive than suffering through yet another math lesson. See the code run? Select  “Catch Up Time” in www.mgsltns.com/games.htm The host is running on Unix, so the link is case sensitive. That’s All Folks

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  • Thoughts on the Nomination Committee Campaign 2014

    - by Testas
    Congratulations to Erin, Andy and Allen on making the Nomination Committee for 2014. As Mark Broadbent (@retracement) stated in his tweet, there’s a great set of individuals for the Nom Com, and I could not agree more. I know Erin and Allen, and I know how much value they will bring to the process. I don’t know Andy as well, but I am sure he will do a great job and I hope I can meet him at PASS soon. The final candidate appointed by the PASS board is Rick Bolesta, who brings a wealth of experience to the process. I also want to take the opportunity to thank all who have voted. Not just for me, but for all the candidates during the election. Your contribution is greatly appreciated. Would I apply for the Nom Com again?  Yes I would. My first election experience has been a learning experience in itself. So I accept the result and look forward to applying next year. Moving on from this, I do want to express my opinion about the lack of international representation in the election process. One of the tweets that I saw after the result was from Adam Machanic (@AdamMachanic) who commented on the lack of international members on the Nom Com. If truth be told, I was disappointed – when the candidate list was released -- that for the second time in recent elections there was a lack of international candidates on the candidate list. It feels that only Brits and Americans partake in such elections. This is a real shame, and I can’t help thinking why this is the case. Hugo Kornelis (@Hugo_Kornelis) wrote a blog here to express his thoughts. He did raise some valid points. I don’t know why there is an absence of international candidates. I know that the team at PASS are looking to improve the situation, so I do not want to give the impression that PASS are doing nothing. For reference please see Bill Graziano’ s article here to see how PASS are addressing the situation. There is a clear direction to change the rules within PASS to give greater inclusion of international members. In addition to this, I wanted to explore a couple of potential approaches to address the situation. I am not saying that they are the right answer, but when I see challenges, I like to bring potential solutions to the table. 1.       Use the PASS mission statement to define a tactical objective that engages community leaders into the election process. If you are not familiar with the PASS mission statement, let me provide it here as laid out on the PASS website. “Empower data professionals who leverage Microsoft technologies to connect, share, and learn through networking, knowledge sharing, and peer-based learning” PASS fulfil this mission statement regularly. Whether you attend SQL Saturday, SQLRally, SQLPASS and BA conference itself. The biggest value of PASS is the ability to bring our profession together. And the 24 hour hop allows you to learn from the comfort of your own office/home. This mission should be extended to define a tactical objectives that bring greater networking and knowledge sharing between PASS Chapter leaders/Regional Mentors and PASS HQ. It should help educate the leaders about the opportunities of elections and how leaders can become involved. I know PASS engage with Chapter leaders on a regular basis to discuss community matters for the benefit of PASS members. How could this be achieved? Perhaps PASS could perform a quarterly virtual meeting that specifically looks at helping leaders become more involved with the election process 2.       Evolve the Global Growth Strategy into a Global Engagement Strategy. One of the remits of the PASS board over the last couple of years is the Global Growth strategy. This has been very successful as we have seen the massive growth of events across the world. For that, I congratulate the board for this success. Perhaps the time is now right to look at solidifying this success, through a Global Engagement Strategy that starts with the collaboration of Chapter Leaders, Regional Mentors and Evangelists in their respective Countries or Regions. The engagement strategy should look at increasing collaboration between community leaders for the benefit of their respective communities. It should also provide a channel for encouraging leaders to put themselves forward for the elections. How could this be achieved? In the UK, there has been a big growth in PASS Chapters and SQL Server Events that was approaching saturation point. The introduction of the Community Engagement Day -- channelled through the SQLBits conference -- has enabled Chapter Leaders to collaborate, connect and share with PASS, Sponsors and Microsoft. It also provides the ability for Chapter Leaders to speak directly to the PASS representatives from PASSHQ. This brings with it the ability for PASS community evangelists to communicate PASS objectives. It has also been the event where we have found out; and/or encouraged, Chapter Leaders to put themselves forward for elections. People like encouragement and validation when going for something like an election, and being able to discuss this with peers at a dedicated event provides a useful platform. PASS has the people in place already to facilitate such an event. Regional Mentors could potentially help organise such events on an annual basis, with PASSHQ providing support in providing a room/Lync access for the event to take place. It would be really good if a PASSHQ representative could attend in person as well.   3.       Restrict candidates to serve only a limited number of terms. A frequent comment I saw on social networking was that the elections can be seen by some as a popularity conference. Perhaps by limiting the number of terms that an individual can serve on either the Nom Com or the BOD, other candidates may be encouraged to be more actively involved within the PASS election process. I don’t think that the current byelaws deal with this particular suggestion. I also saw a couple of tweets that stated that more active community members did not apply for the Nom Com. I struggled to understand how the individuals of the tweets measured “more active”. It just also further solidified the subjective nature of elections. In the absence of how candidates are put forward for the elections. Then a restriction of terms enables the opportunity to be extended to others. How could this be achieved? Set a resolution that is put to a community vote as to the viability of such a solution. For example, the questions for the vote could be: Should individuals in the Nom Com and BoD be limited to a certain number of terms?  Yes/No. What is the maximum number of terms a candidate could serve?   It would be simple to execute such a vote, and the community will have an opportunity to have a say in an important aspect of the PASS organisation. And is the change is successful, then add it as a byelaw.   So there are some of my thoughts. I am not saying they are right or wrong. But I do hope that there is a concerted effort to encourage more candidates from other reaches of the Globe to become involved with future elections.   It would be good to hear your thoughts   Thanks   Chris

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  • WhatsApp &amp; Tasker for Android &ndash; Read &amp; Write messages

    - by Shaurya Anand
    So, I finally gave up on all my previous the Microsoft Mobile/Phone OS devices and made my switch to Android this year. I am using my Samsung Galaxy Note GT-N7000 with CyanogenMod 9.1.0 (http://get.cm/get/jenkins/7086/cm-9.1.0-n7000.zip) and ClockworkMod 6.0.1.2 (http://download2.clockworkmod.com/recoveries/recovery-clockwork-6.0.1.2-n7000.zip) since August this year and I am so happy with the performance and the flexibility it offers me. As a software developer by profession, I would expect most of my gadget to be highly customizable and programmable (one time or at intervals) to suit my needs as close as it can. I was introduced to Automation for Android – Tasker (https://play.google.com/store/apps/details?id=net.dinglisch.android.taskerm&hl=en) via reddit (http://www.reddit.com/r/tasker) and the word ‘automation’ was enough for me to dive right into this app. Only automation that I did earlier was switching profiles depending on location on there phones. And now, just imagine a complete set of possibilities that can be automate on the phone or via the phone. I did my research and found a couple of other tools that do the same/as close as what Tasker can do and few of them are even free. There’s one even by Microsoft called on{X} (https://play.google.com/store/apps/details?id=com.microsoft.onx.app&hl=en). Microsoft’s on{X} really caught my eye. You can write code for your phone on the web application by them, deploy it on your phone and even trace the flow all using your PC. Really brilliant, I love the fact that it’s all JavaScript. Here comes the but, it is still very very young and it’s policy of accessing my News Feed on Facebook is not something that I can not digest. On{X} is good, but as I said earlier, the API is not very mature and hence, I gave up on it. I bought Tasker, the best 5,00 € I spent in ages and I want to talk about it in this post. I am still a “noob” while operating this tool, but I tried my shot at automating WhatsApp (https://play.google.com/store/apps/details?id=com.whatsapp&hl=en), a popular messenger for various platform. The requirement for the automation is that, if I send a WhatsApp ‘wru’ message to the phone, it should respond back giving the location and battery level of my phone. It could be useful, if you like to locate your misplaced phone or automatically reply to your partner/friend, honestly, I don’t know what you will use it - through this post, I am just introducing automating WhatsApp using Tasker. Before we begin, the following script only works when your phone is rooted as we will be accessing the WhatsApp database and type some special characters like ‘:’. Let’s follow the code line by line: Profile:         Location request from XYZ. (12) // Name of your profile. Event:         Notification [ Owner Application:WhatsApp Title:* ] // When a new notification comes from WhatsApp, this event is fired. Read the end note, if you face problems with Chrome app after enabling Tasker accessibility. Enter:         A1: Run Shell [ Command:sqlite3 // We will access the WhatsApp database and check if the message comes from designated phone number or not. We mustn’t reply to every message.                 /data/data/com.whatsapp/databases/msgstore.db "SELECT _id, data FROM                  messages WHERE key_from_me='0' AND key_remote_jid LIKE '%XXXXXXXXXXX%' // Replace XXXXXXXXXXX with the phone number of your message sender.                 ORDER BY _id DESC LIMIT 1;" Timeout (Seconds):10 Use Root:On Store // I made a timeout for 10 seconds, if in case WhatsApp is busy accessing the database.                 Result In:%WHATSAPP_CURRREQ ] // Store the read Id and the last message on to the variable %WHATSAPP_CURRREQ         A2: If [ %WHATSAPP_CURRREQ ~R .*[wW][rR][uU].* ] // Check if the pattern of the message is correct and we are all set to send the location.                 A3: If [ %WHATSAPP_CURRREQ !~ %WHATSAPP_LASTREQ ] // Verify that the message is different from the last request. Remember every message has a unique Id.                         A4: Notify [ Title:WhatsApp location request... Text:Sending location // Just a notification that the location message is being prepared.                                 to Krati Gupta... Icon:<icon> Number:0 Permanent:On Priority:3 ] // Make a note it is a permanent notification, we will clear it later.                         A5: Secure Settings [ Configuration:Pattern Lock Disabled // I am disabling the pattern lock, that I use using the plugin Secure Settings.                                 Package:com.intangibleobject.securesettings.plugin Name:Secure // You can download the plugin from here: https://play.google.com/store/apps/details?id=com.intangibleobject.securesettings.plugin&hl=en                                 Settings ]                         A6: Secure Settings [ Configuration:Keyguard Disabled // Disable the keygaurd, it is useful, when your phone is on lock and you want to automate everything, even the typing.                                 Package:com.intangibleobject.securesettings.plugin Name:Secure                                 Settings ]                         A7: Secure Settings [ Configuration:GPS Enabled // Pretty clear, turn on the GPS and get location at A8                                 Package:com.intangibleobject.securesettings.plugin Name:Secure                                 Settings ]                         A8: AutoShortcut [ Configuration:WhatsApp: Some One // I am using AutoShortcut plugin (https://play.google.com/store/apps/details?id=com.joaomgcd.autoshortcut) to start WhatsApp with the indented recipient.                                 Package:com.joaomgcd.autoshortcut Name:AutoShortcut ] // Replace Some One, actually choose it from the plugin, the right recipient.                         A9: Get Location [ Source:Any Timeout (Seconds):30 Continue Task // I am getting the location, timeout is 30 seconds, adjust it accordingly.                                 Immediately:Off Keep Tracking:Off ]                         A10: Secure Settings [ Configuration:Screen Dim // Now, this extension of the plugin Secure Settings, wakes your device so that you can type out the string on the WhatsApp app.                                 5 Seconds Package:com.intangibleobject.securesettings.plugin                                 Name:Secure Settings ]                         A11: Run Shell [ Command:input text // Now, I am using the shell script to type the text to the window, because the ‘:’ while not be typed from the Type task in Tasker.                                 LOCATION:maps.google.com/maps?q=%LOC Timeout (Seconds):0 Use Root:On // And also, this is way faster, but remember you need root for this, not for the other way of typing.                                 Store Result In: ]                         A12: Dpad [ Button:Right Repeat Times:1 ] // Focus the Send button                         A13: Dpad [ Button:Press Repeat Times:1 ] // And press it.                         A14: Dpad [ Button:Left Repeat Times:1 ] // Get back to the typing box.                         A15: Run Shell [ Command:input text LOCATION_ACCURACY:%LOCACC Timeout                                 (Seconds):0 Use Root:On Store Result In: ]                         A16: Dpad [ Button:Right Repeat Times:1 ]                         A17: Dpad [ Button:Press Repeat Times:1 ]                         A18: Dpad [ Button:Left Repeat Times:1 ]                         A19: Run Shell [ Command:input text BATTERY_LEVEL:%BATT% Timeout // I am adding Battery level in my case as well.                                 (Seconds):0 Use Root:On Store Result In: ]                         A20: Dpad [ Button:Right Repeat Times:1 ]                         A21: Dpad [ Button:Press Repeat Times:1 ]                         A22: Variable Set [ Name:%WHATSAPP_LASTREQ To:%WHATSAPP_CURRREQ Do // And now, we say, request is done.                                 Maths:Off Append:Off ]                         A23: Button [ Button:Back ] // I am exiting the WhatsApp nicely and not killing it. If you are the murderer kind, kill it, just know, you don’t have any place in the heaven.                         A24: Button [ Button:Back ]                         A25: Notify Cancel [ Title: Warn Not Exist:Off ] // Remove the permanent notification.                         A26: Notify [ Title:WhatsApp location request Text:Location sent // Make a temporary notification, and say, location is sent.                                 successfully. Icon:<icon> Number:0 Permanent:Off Priority:3 ]                                                         A27: Secure Settings [ Configuration:GPS Disabled // Disable all the horrible things we turned on earlier.                                 Package:com.intangibleobject.securesettings.plugin Name:Secure                                 Settings ]                         A28: Secure Settings [ Configuration:Pattern Lock Enabled                                 Package:com.intangibleobject.securesettings.plugin Name:Secure                                 Settings ]                         A29: Secure Settings [ Configuration:Keyguard Enabled                                 Package:com.intangibleobject.securesettings.plugin Name:Secure                                 Settings ]                 A30: End If         A31: End If Download this Task from here: http://db.tt/9vRmbhyb That’s it in the above small example – you can read/write messages from/to WhatsApp app. I am using n7000-cm9.1-cwr6. Oh yea, and if you are having the Talkback auto enabled for Chrome browser, you need to turn Off the Web scripts to run. Tasker is amazing, I have automated a lot of tasks using this tool. I will share a few none generic ones with you in my coming post here.

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  • ArchBeat Link-o-Rama for November 15, 2012

    - by Bob Rhubart
    WLST Starting and Stopping a WebLogic Environment | Rene van Wijk Oracle ACE Rene van Wijk explores how to start a server with as little input as possible. Developing and Enforcing a BYOD Policy | Darin Pendergraft Darin Pendergraft's post includes links to a recent Mobile Access Policy Survey by SANS as well as registration information for a Nov 15 webcast featuring security expert Tony DeLaGrange from Secure Ideas, SANS instructor, attorney and technology law expert Ben Wright, and Oracle IDM product manager Lee Howarth. Cloud Integration White Paper Now Available |Bruce Tierney Bruce Tierney shares an overview of Cloud Integration - A Comprehensive Solution, a new white paper he co-authored with David Baum, Rajesh Raheja, Bruce Tierney, and Vijay Pawar. My iPad & This Cloud Thing | Floyd Teter Oracle ACE Director Floyd Teter explains why the Cloud is making it possible for him to use his iPad for tasks previously relegated to his laptop, and why this same scenario is likely to play out for a great many people. 3 steps to a cloud database strategy that works | InfoWorld "Every day, cloud-based databases add more features, decrease in cost, and become better at handling prime-time business," says InfoWorld blogger David Linthicum. "However, enterprise IT is reluctant to move data to public clouds, citing the tried-and-true excuses of security, privacy, and compliance. Although some have valid points, their reasons often boil down to 'I don't wanna.'" Oracle VM Templates for EBS 12.1.3 for Exalogic Now Available | Elke Phelps "The templates contain all the required elements to create an Oracle E-Business Suite R12 demonstration system on an Exalogic server," says Elke Phelps. "You can use these templates to quickly build an EBS 12.1.3 demonstration environment, bypassing the operating system and the software install (via the EBS Rapid Install)." Thought for the Day "A good plan executed today always beats a perfect plan executed tomorrow." — George S. Patton (November 11, 1885 - December 21, 1945) Source: SoftwareQuotes.com

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  • MIX 2010 Covert Operations Day 4

    - by GeekAgilistMercenary
    The Microsoft Azure Cloud is looking pretty solid compared to just a few months ago.  The storage mechanisms in the cloud now are blobs, drives, tables, and queues.  Also, not to forget, is SQL Azure.  I won’t dive too much into that, as most will know what SQL Server is, and SQL Azure is pretty much just a hosted SQL Server instance. The blobs are generally geared toward holding binary type data, images and those types of things.  The tables are huge key value type stores.  The drives are VHD, which are virtual hard drives.  The queues are just queues used for workflow and also to store messages back and forth in a queue. These methods are accessible via REST, which makes application development against the storage services extremely easy.  This is a big plus point as REST services are a preferred way to connect and interact with data storage.  It also sets up Silverlight as a prime framework to utilize services. Day 4 I pretty much dedicated to reviewing these cloud services and finishing up work related development.  With that, I'm wrapping up my MIX 2010 blog coverage.  Now back to your regularly scheduled programming. Original entry.

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  • Grow Your Business with Security

    - by Darin Pendergraft
    Author: Kevin Moulton Kevin Moulton has been in the security space for more than 25 years, and with Oracle for 7 years. He manages the East EnterpriseSecurity Sales Consulting Team. He is also a Distinguished Toastmaster. Follow Kevin on Twitter at twitter.com/kevin_moulton, where he sometimes tweets about security, but might also tweet about running, beer, food, baseball, football, good books, or whatever else grabs his attention. Kevin will be a regular contributor to this blog so stay tuned for more posts from him. It happened again! There I was, reading something interesting online, and realizing that a friend might find it interesting too. I clicked on the little email link, thinking that I could easily forward this to my friend, but no! Instead, a new screen popped up where I was asked to create an account. I was expected to create a User ID and password, not to mention providing some personally identifiable information, just for the privilege of helping that website spread their word. Of course, I didn’t want to have to remember a new account and password, I didn’t want to provide the requisite information, and I didn’t want to waste my time. I gave up, closed the web page, and moved on to something else. I was left with a bad taste in my mouth, and my friend might never find her way to this interesting website. If you were this content provider, would this be the outcome you were looking for? A few days later, I had a similar experience, but this one went a little differently. I was surfing the web, when I happened upon some little chotcke that I just had to have. I added it to my cart. When I went to buy the item, I was again brought to a page to create account. Groan! But wait! On this page, I also had the option to sign in with my OpenID account, my Facebook account, my Yahoo account, or my Google Account. I have all of those! No new account to create, no new password to remember, and no personally identifiable information to be given to someone else (I’ve already given it all to those other guys, after all). In this case, the vendor was easy to deal with, and I happily completed the transaction. That pleasant experience will bring me back again. This is where security can grow your business. It’s a differentiator. You’ve got to have a presence on the web, and that presence has to take into account all the smart phones everyone’s carrying, and the tablets that took over cyber Monday this year. If you are a company that a customer can deal with securely, and do so easily, then you are a company customers will come back to again and again. I recently had a need to open a new bank account. Every bank has a web presence now, but they are certainly not all the same. I wanted one that I could deal with easily using my laptop, but I also wanted 2-factor authentication in case I had to login from a shared machine, and I wanted an app for my iPad. I found a bank with all three, and that’s who I am doing business with. Let’s say, for example, that I’m in a regular Texas Hold-em game on Friday nights, so I move a couple of hundred bucks from checking to savings on Friday afternoons. I move a similar amount each week and I do it from the same machine. The bank trusts me, and they trust my machine. Most importantly, they trust my behavior. This is adaptive authentication. There should be no reason for my bank to make this transaction difficult for me. Now let's say that I login from a Starbucks in Uzbekistan, and I transfer $2,500. What should my bank do now? Should they stop the transaction? Should they call my home number? (My former bank did exactly this once when I was taking money out of an ATM on a business trip, when I had provided my cell phone number as my primary contact. When I asked them why they called my home number rather than my cell, they told me that their “policy” is to call the home number. If I'm on the road, what exactly is the use of trying to reach me at home to verify my transaction?) But, back to Uzbekistan… Should my bank assume that I am happily at home in New Jersey, and someone is trying to hack into my account? Perhaps they think they are protecting me, but I wouldn’t be very happy if I happened to be traveling on business in Central Asia. What if my bank were to automatically analyze my behavior and calculate a risk score? Clearly, this scenario would be outside of my typical behavior, so my risk score would necessitate something more than a simple login and password. Perhaps, in this case, a one-time password to my cell phone would prove that this is not just some hacker half way around the world. But, what if you're not a bank? Do you need this level of security? If you want to be a business that is easy to deal with while also protecting your customers, then of course you do. You want your customers to trust you, but you also want them to enjoy doing business with you. Make it easy for them to do business with you, and they’ll come back, and perhaps even Tweet about it, or Like you, and then their friends will follow. How can Oracle help? Oracle has the technology and expertise to help you to grown your business with security. Oracle Adaptive Access Manager will help you to prevent fraud while making it easier for your customers to do business with you by providing the risk analysis I discussed above, step-up authentication, and much more. Oracle Mobile and Social Access Service will help you to secure mobile access to applications by expanding on your existing back-end identity management infrastructure, and allowing your customers to transact business with you using the social media accounts they already know. You also have device fingerprinting and metrics to help you to grow your business securely. Security is not just a cost anymore. It’s a way to set your business apart. With Oracle’s help, you can be the business that everyone’s tweeting about. Image courtesy of Flickr user shareski

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  • Guide to MySQL & NoSQL, Webinar Q&A

    - by Mat Keep
    0 0 1 959 5469 Homework 45 12 6416 14.0 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:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; 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; mso-ansi-language:EN-US;} Yesterday we ran a webinar discussing the demands of next generation web services and how blending the best of relational and NoSQL technologies enables developers and architects to deliver the agility, performance and availability needed to be successful. Attendees posted a number of great questions to the MySQL developers, serving to provide additional insights into areas like auto-sharding and cross-shard JOINs, replication, performance, client libraries, etc. So I thought it would be useful to post those below, for the benefit of those unable to attend the webinar. Before getting to the Q&A, there are a couple of other resources that maybe useful to those looking at NoSQL capabilities within MySQL: - On-Demand webinar (coming soon!) - Slides used during the webinar - Guide to MySQL and NoSQL whitepaper  - MySQL Cluster demo, including NoSQL interfaces, auto-sharing, high availability, etc.  So here is the Q&A from the event  Q. Where does MySQL Cluster fit in to the CAP theorem? A. MySQL Cluster is flexible. A single Cluster will prefer consistency over availability in the presence of network partitions. A pair of Clusters can be configured to prefer availability over consistency. A full explanation can be found on the MySQL Cluster & CAP Theorem blog post.  Q. Can you configure the number of replicas? (the slide used a replication factor of 1) Yes. A cluster is configured by an .ini file. The option NoOfReplicas sets the number of originals and replicas: 1 = no data redundancy, 2 = one copy etc. Usually there's no benefit in setting it >2. Q. Interestingly most (if not all) of the NoSQL databases recommend having 3 copies of data (the replication factor).    Yes, with configurable quorum based Reads and writes. MySQL Cluster does not need a quorum of replicas online to provide service. Systems that require a quorum need > 2 replicas to be able to tolerate a single failure. Additionally, many NoSQL systems take liberal inspiration from the original GFS paper which described a 3 replica configuration. MySQL Cluster avoids the need for a quorum by using a lightweight arbitrator. You can configure more than 2 replicas, but this is a tradeoff between incrementally improved availability, and linearly increased cost. Q. Can you have cross node group JOINS? Wouldn't that run into the risk of flooding the network? MySQL Cluster 7.2 supports cross nodegroup joins. A full cross-join can require a large amount of data transfer, which may bottleneck on network bandwidth. However, for more selective joins, typically seen with OLTP and light analytic applications, cross node-group joins give a great performance boost and network bandwidth saving over having the MySQL Server perform the join. Q. Are the details of the benchmark available anywhere? According to my calculations it results in approx. 350k ops/sec per processor which is the largest number I've seen lately The details are linked from Mikael Ronstrom's blog The benchmark uses a benchmarking tool we call flexAsynch which runs parallel asynchronous transactions. It involved 100 byte reads, of 25 columns each. Regarding the per-processor ops/s, MySQL Cluster is particularly efficient in terms of throughput/node. It uses lock-free minimal copy message passing internally, and maximizes ID cache reuse. Note also that these are in-memory tables, there is no need to read anything from disk. Q. Is access control (like table) planned to be supported for NoSQL access mode? Currently we have not seen much need for full SQL-like access control (which has always been overkill for web apps and telco apps). So we have no plans, though especially with memcached it is certainly possible to turn-on connection-level access control. But specifically table level controls are not planned. Q. How is the performance of memcached APi with MySQL against memcached+MySQL or any other Object Cache like Ecache with MySQL DB? With the memcache API we generally see a memcached response in less than 1 ms. and a small cluster with one memcached server can handle tens of thousands of operations per second. Q. Can .NET can access MemcachedAPI? Yes, just use a .Net memcache client such as the enyim or BeIT memcache libraries. Q. Is the row level locking applicable when you update a column through memcached API? An update that comes through memcached uses a row lock and then releases it immediately. Memcached operations like "INCREMENT" are actually pushed down to the data nodes. In most cases the locks are not even held long enough for a network round trip. Q. Has anyone published an example using something like PHP? I am assuming that you just use the PHP memcached extension to hook into the memcached API. Is that correct? Not that I'm aware of but absolutely you can use it with php or any of the other drivers Q. For beginner we need more examples. Take a look here for a fully worked example Q. Can I access MySQL using Cobol (Open Cobol) or C and if so where can I find the coding libraries etc? A. There is a cobol implementation that works well with MySQL, but I do not think it is Open Cobol. Also there is a MySQL C client library that is a standard part of every mysql distribution Q. Is there a place to go to find help when testing and/implementing the NoSQL access? If using Cluster then you can use the [email protected] alias or post on the MySQL Cluster forum Q. Are there any white papers on this?  Yes - there is more detail in the MySQL Guide to NoSQL whitepaper If you have further questions, please don’t hesitate to use the comments below!

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  • What GUI tools are available for which DVCS?

    - by Macneil
    When I worked at Sun, we used a DVC system called Forte SCCS/Teamware, which used the old SCCS file format, but was a true distributed source code revision control system. One nice feature is that it had strong GUI support: You could bringover and putback changes by simply clicking and dragging. It would draw trees/graphs showing how workspaces relate to each other. You also could have a graph view to display a single file's complete history, which might have had several branches and merges. Allowing you to compare any two points. It also had a strong visual merge tool, to let you accept changes from one of two conflicting files. Naturally, many of the current DVCSs have command line support for these operations, but I'm looking for GUI support in order to use this in a lower-level undergraduate course I'll be teaching. I'm not saying the Forte Teamware solution was perfect, but it did seem to be ahead of the curve. Unfortunately, it's not a viable option to use for my class. Question: What support do the current DVCSs have with regards to GUIs? Do any of them work on Windows, and not just Linux? Are they "ready for prime-time" or still works in progress? Are these standalone or built as plug-ins, e.g., for Eclipse? Note: To help keep this discussion focused I'm only interested in GUI tools. And not a meta-discussion if GUI tools should be used in teaching.

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  • Rebuilding CoasterBuzz, Part III: The architecture using the "Web stack of love"

    - by Jeff
    This is the third post in a series about rebuilding one of my Web sites, which has been around for 12 years. I hope to relaunch in the next month or two. More: Part I: Evolution, and death to WCF Part II: Hot data objects I finally hit a point in the re-do of CoasterBuzz where I feel like the major pieces are in place... rewritten, ported and what not, so that I can focus now on front-end design and more interesting creative problems. I've been asked on more than one occasion (OK, just twice) what's going on under the covers, so I figure this might be a good time to explain the overall architecture. As it turns out, I'm using a whole lof of the "Web stack of love," as Scott Hanselman likes to refer to it. Oh that Hanselman. First off, at the center of it all, is BizTalk. Just kidding. That's "enterprise architecture" humor, where every discussion starts with how they'll use BizTalk. Here are the bigger moving parts: It's fairly straight forward. A common library lives in a number of Web apps, all of which are (or will be) powered by ASP.NET MVC 4. They all talk to the same database. There is the main Web site, which also has the endpoint for the Silverlight-based Feed app. The cstr.bz site handles redirects, which are generated when news items are published and sent to Twitter. Facebook publishing is handled via the RSS Graffiti Facebook app. The API site handles requests from the Windows Phone app. The main site depends very heavily on POP Forums, the open source, MVC-based forum I maintain. It serves a number of functions, primarily handling users. These user objects serve in non-forum roles to handle things like news and database contributions, maintaining track records (coaster nerd for "list of rides I've been on") and, perhaps most importantly, paid club memberships. Before I get into more specifics, note that the "glue" for everything is Ninject, the dependency injection framework. I actually prefer StructureMap these days, but I started with Ninject in POP Forums a long time ago. POP Forums has a static class, PopForumsActivation, that new's up an instance of the container, and you can call it from where ever. The downside is that the forums require Ninject in your MVC app as the default dependency resolver. At some point, I'll decouple it, but for now it's not in the way. In the general sense, the entire set of apps follow a repository-service-controller-view pattern. Repos just do data access, service classes do business logic, controllers compose and route, views view. The forum also provides Scoring Game functionality. The Scoring Game is a reasonably abstract framework to award users points based on certain actions, and then award achievements when a certain number of point events happen. For example, the forum already awards a point when someone plus-one's a post you made. You can set up an achievement that says, "Give the user an award when they've had 100 posts plus'd." It also does zero-point entries into the ledger, so if you make a post, you could award an achievement based on 100 posts made. Wiring in the scoring game to CoasterBuzz functionality is just a matter of going to the Ninject container and getting an instance of the event publisher, and passing it events. Forum adapters were introduced into POP Forums a few versions ago, and they can intercept the model generated for forum topic lists and threads and designate an alternate view. These are used to make the "Day in Pictures" forum, where users can upload photos as frame-by-frame photo threads. Another adapter adds an association UI, so users can associate specific amusement parks with their trip report posts. The Silverlight-based Feed app talks to a simple JSON endpoint in the main app. This uses an underlying library I wrote ages ago, simply called Feeds, that aggregates event information. You inherit from a base class that creates instances of a publisher interface, and then use that class to send it an event type and any number of data fields. Feeds has two publishers: One is to the database, and that's used for the endpoint that talks to the Silverlight app. The second publisher publishes to Twitter, if the event is of the type "news." The wiring is a little strange, because for the new posts and topics events, I'm actually pulling out the forum repository classes from the Ninject container and replacing them with overridden methods to publish. I should probably be doing this at the service class level, but whatever. It's my mess. cstr.bz doesn't do anything interesting. It looks up the path, and if it has a match, does a 301 redirect to the long URL. The API site just serves up JSON for the Windows Phone app. The Windows Phone app is Silverlight, of course, and there isn't much to it. It does use the control toolkit, but beyond that, it relies on a simple class that creates a Webclient and calls the server for JSON to deserialize. The same class is now used by the Feed app, which used to use WCF. Simple is better. Data access in POP Forums is all straight SQL, because a lot of it was ported from the ASP.NET version. Most CoasterBuzz data access is handled by the Entity Framework, using the code-first model. The context class in this case does a lot of work to make sure that the table and key mapping works, since much of it breaks from the normal conventions of EF. One of the more powerful things you can do with EF, once you understand the little gotchas, is split tables by row into different entities. For example, a roller coaster photo has everything in the same row, including the metadata, the thumbnail bytes and the image itself. Obviously, if you want to get a list of photos to iterate over in a view, you don't want to get the image data. The use of navigation properties makes it easier to get just what you want. The front end includes Razor views in MVC, and jQuery is used for client-side goodness. I'm also using jQuery UI in a few places, for tabs, a dialog box and autocomplete. I'm also, tentatively, using jQuery Mobile. I've already ported most forum views to Mobile, but they need some work as v1.1 isn't finished yet. I'm not sure if I'll ship CoasterBuzz with mobile views or not yet. It's on the radar, but not something in my delivery criteria. That covers all of the big frameworks in play. Next time I hope to talk more about the front-end experience, which to me is where most of the fun is these days. Hoping to launch in the next month or two. Getting tired of looking at the old site!

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  • Encrypted home breaks on login

    - by berkes
    My home is encrypted, which breaks the login. Gnome and other services try to find all sorts of .files, write to them, read from them and so on. E.g. .ICEauthority. They are not found (yet) because at that moment the home is still encrypted. I do not have automatic login set, since that has known issues with encrypted home in Ubuntu. When I go trough the following steps, there is no problem: boot up the system. [ctr][alt][F1], login. run ecryptfs-mount-private [ctr][alt][F7], done. Can now login. I may have some setting wrong, but have no idea where. I suspect ecryptfs-mount-private should be ran earlier in bootstrap, but do not know how to make it so. Some issues that may cause trouble: I have a fingerprint reader, it works for login and PAM. I have three keyrings in seahorse, containing passwords from old machines (backups). Not just one. Suggestion was that the PAM settings are wrong, so here are the relevant parts from /etc/pam.d/common-auth. # here are the per-package modules (the "Primary" block) auth [success=3 default=ignore] pam_fprintd.so auth [success=2 default=ignore] pam_unix.so nullok_secure try_first_pass auth [success=1 default=ignore] pam_winbind.so krb5_auth krb5_ccache_type=FILE cached_login try_first_pass # here's the fallback if no module succeeds auth requisite pam_deny.so # prime the stack with a positive return value if there isn't one already; # this avoids us returning an error just because nothing sets a success code # since the modules above will each just jump around auth required pam_permit.so # and here are more per-package modules (the "Additional" block) auth optional pam_ecryptfs.so unwrap # end of pam-auth-update config I am not sure about how this configuration works, but ut seems that maybe the*optional* in auth optional pam_ecryptfs.so unwrap is causing the ecryptfs to be ignored?

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  • Amazon Upgrades FreeTime; More Content for the Kid-Friendly Walled Garden

    - by Jason Fitzpatrick
    Earlier this year Amazon introduced FreeTime, a walled garden area intended to provide a kids-only app gallery on the Kindle Fire. It was up to parents to populate the content but now, with the recent update, Amazon brings together unlimited books, movies, games, and apps. Intended for children ages 3-8 the upgraded service eschews the you-pick-it-all approach and goes with a hand-curated collection of games, educational apps, books and more. In addition to the pile of hand-curated content, FreeTime also has built in time limits and individual profiles for different children. Every Kindle Fire, Kindle Fire HD, and Kindle Fire HD 8.9″ user can try out the service for thirty days without charge. After the thirty day trial the subscription price is $4.99 per month ($2.99 for Prime members). Hit up the link below to check out the full description of the service. Amazon FreeTime [Amazon] Our Geek Trivia App for Windows 8 is Now Available Everywhere How To Boot Your Android Phone or Tablet Into Safe Mode HTG Explains: Does Your Android Phone Need an Antivirus?

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  • Testing Workflows &ndash; Test-After

    - by Timothy Klenke
    Originally posted on: http://geekswithblogs.net/TimothyK/archive/2014/05/30/testing-workflows-ndash-test-after.aspxIn this post I’m going to outline a few common methods that can be used to increase the coverage of of your test suite.  This won’t be yet another post on why you should be doing testing; there are plenty of those types of posts already out there.  Assuming you know you should be testing, then comes the problem of how do I actual fit that into my day job.  When the opportunity to automate testing comes do you take it, or do you even recognize it? There are a lot of ways (workflows) to go about creating automated tests, just like there are many workflows to writing a program.  When writing a program you can do it from a top-down approach where you write the main skeleton of the algorithm and call out to dummy stub functions, or a bottom-up approach where the low level functionality is fully implement before it is quickly wired together at the end.  Both approaches are perfectly valid under certain contexts. Each approach you are skilled at applying is another tool in your tool belt.  The more vectors of attack you have on a problem – the better.  So here is a short, incomplete list of some of the workflows that can be applied to increasing the amount of automation in your testing and level of quality in general.  Think of each workflow as an opportunity that is available for you to take. Test workflows basically fall into 2 categories:  test first or test after.  Test first is the best approach.  However, this post isn’t about the one and only best approach.  I want to focus more on the lesser known, less ideal approaches that still provide an opportunity for adding tests.  In this post I’ll enumerate some test-after workflows.  In my next post I’ll cover test-first. Bug Reporting When someone calls you up or forwards you a email with a vague description of a bug its usually standard procedure to create or verify a reproduction plan for the bug via manual testing and log that in a bug tracking system.  This can be problematic.  Often reproduction plans when written down might skip a step that seemed obvious to the tester at the time or they might be missing some crucial environment setting. Instead of data entry into a bug tracking system, try opening up the test project and adding a failing unit test to prove the bug.  The test project guarantees that all aspects of the environment are setup properly and no steps are missing.  The language in the test project is much more precise than the English that goes into a bug tracking system. This workflow can easily be extended for Enhancement Requests as well as Bug Reporting. Exploratory Testing Exploratory testing comes in when you aren’t sure how the system will behave in a new scenario.  The scenario wasn’t planned for in the initial system requirements and there isn’t an existing test for it.  By definition the system behaviour is “undefined”. So write a new unit test to define that behaviour.  Add assertions to the tests to confirm your assumptions.  The new test becomes part of the living system specification that is kept up to date with the test suite. Examples This workflow is especially good when developing APIs.  When you are finally done your production API then comes the job of writing documentation on how to consume the API.  Good documentation will also include code examples.  Don’t let these code examples merely exist in some accompanying manual; implement them in a test suite. Example tests and documentation do not have to be created after the production API is complete.  It is best to write the example code (tests) as you go just before the production code. Smoke Tests Every system has a typical use case.  This represents the basic, core functionality of the system.  If this fails after an upgrade the end users will be hosed and they will be scratching their heads as to how it could be possible that an update got released with this core functionality broken. The tests for this core functionality are referred to as “smoke tests”.  It is a good idea to have them automated and run with each build in order to avoid extreme embarrassment and angry customers. Coverage Analysis Code coverage analysis is a tool that reports how much of the production code base is exercised by the test suite.  In Visual Studio this can be found under the Test main menu item. The tool will report a total number for the code coverage, which can be anywhere between 0 and 100%.  Coverage Analysis shouldn’t be used strictly for numbers reporting.  Companies shouldn’t set minimum coverage targets that mandate that all projects must have at least 80% or 100% test coverage.  These arbitrary requirements just invite gaming of the coverage analysis, which makes the numbers useless. The analysis tool will break down the coverage by the various classes and methods in projects.  Instead of focusing on the total number, drill down into this view and see which classes have high or low coverage.  It you are surprised by a low number on a class this is an opportunity to add tests. When drilling through the classes there will be generally two types of reaction to a surprising low test coverage number.  The first reaction type is a recognition that there is low hanging fruit to be picked.  There may be some classes or methods that aren’t being tested, which could easy be.  The other reaction type is “OMG”.  This were you find a critical piece of code that isn’t under test.  In both cases, go and add the missing tests. Test Refactoring The general theme of this post up to this point has been how to add more and more tests to a test suite.  I’ll step back from that a bit and remind that every line of code is a liability.  Each line of code has to be read and maintained, which costs money.  This is true regardless whether the code is production code or test code. Remember that the primary goal of the test suite is that it be easy to read so that people can easily determine the specifications of the system.  Make sure that adding more and more tests doesn’t interfere with this primary goal. Perform code reviews on the test suite as often as on production code.  Hold the test code up to the same high readability standards as the production code.  If the tests are hard to read then change them.  Look to remove duplication.  Duplicate setup code between two or more test methods that can be moved to a shared function.  Entire test methods can be removed if it is found that the scenario it tests is covered by other tests.  Its OK to delete a test that isn’t pulling its own weight anymore. Remember to only start refactoring when all the test are green.  Don’t refactor the tests and the production code at the same time.  An automated test suite can be thought of as a double entry book keeping system.  The unchanging, passing production code serves as the tests for the test suite while refactoring the tests. As with all refactoring, it is best to fit this into your regular work rather than asking for time later to get it done.  Fit this into the standard red-green-refactor cycle.  The refactor step no only applies to production code but also the tests, but not at the same time.  Perhaps the cycle should be called red-green-refactor production-refactor tests (not quite as catchy).   That about covers most of the test-after workflows I can think of.  In my next post I’ll get into test-first workflows.

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  • Top 10 Posts in 2010

    - by dwahlin
    Blogging’s a lot of fun and a great way to share what you’ve learned. It’s also a great way to learn based upon comments people leave that help you see things in an entirely new way in some cases.  Since we’ve now moved on to 2011 (Happy New Year’s!) I wanted to list the Top 10 posts from my blog during 2010 based on individual views.  Thanks to everyone who follows my blog and adds comments from time to time. Here’s wishing everyone a great 2011!   1. Reducing Code by Using jQuery Templates 2. Integrating HTML into Silverlight Applications 3. Silverlight is Dead, the Moon is Made of Cheese, and HTML 5 is Ready for Prime Time 4. Understanding the Role of Commanding in Silverlight 4 Applications 5. New Article – Getting Started with WCF RIA Services 6. Simplify Your Code with LINQ 7. My Favorite iPad Apps….So Far 8. Final Release of Silverlight Tools for Visual Studio 2010 Released 9. Handling WCF Service Paths in Silverlight 4 – Relative Path Support 10. Tales from the Trenches – Building a Real-World Silverlight Line of Business Application   Getting Started with the MVVM Pattern in Silverlight Applications – Posted late 2009 so I’m giving it honorable mention status since it’s still one of the most popular posts.

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  • flex and bison: wrong output

    - by user2972227
    I am doing a homework using flex and bison to make a complex number calculator. But my program cannot give a correct output. .lex file: %option noyywrap %{ #include<stdio.h> #include<stdlib.h> #include "complex_cal.h" #define YYSTYPE complex #include "complex_cal.tab.h" void RmWs(char* str); %} /* Add your Flex definitions here */ /* Some definitions are already provided to you*/ ws [ \t]+ digits [0-9] number (0|[1-9]+{digits}*)\.?{digits}* im [i] complexnum {ws}*[-]*{ws}*{number}{ws}*[+|-]{ws}*{number}{ws}*{im}{ws}* op [-+*/()] %% {complexnum} {RmWs(yytext); sscanf(yytext,"%lf %lf",&(yylval.real),&(yylval.img)); return CNUMBER;} {ws} /**/ {op} return *yytext; %% /* function provided to student to remove */ /* all the whitespaces from a string. */ void RmWs(char* str){ int i=0,j=0; char temp[strlen(str)+1]; strcpy(temp,str); while (temp[i]!='\0'){ while (temp[i]==' '){i++;} str[j]=temp[i]; i++; j++; } str[j]='\0'; } .y file: %{ #include <stdio.h> #include <stdlib.h> #include "complex_cal.h" /* prototypes of the provided functions */ complex complex_add (complex, complex); complex complex_sub (complex, complex); complex complex_mul (complex, complex); complex complex_div (complex, complex); /* prototypes of the provided functions */ int yylex(void); int yyerror(const char*); %} %token CNUMBER %left '+' '-' %left '*' '/' %nonassoc '(' ')' %% /* start: Add your grammar rules and actions here */ complexexp: complexexp '+' complexexpmultidiv {$$=complex_add($1, $3);} | complexexp '-' complexexpmultidiv {$$=complex_sub($1, $3);} | complexexpmultidiv {$$.real=$1.real;$$.img=$1.img;} ; complexexpmultidiv: complexexpmultidiv '*' complexsimple {$$=complex_mul($1, $3);} | complexexpmultidiv '/' complexsimple {$$=complex_div($1, $3);} | complexsimple {$$.real=$1.real;$$.img=$1.img;} ; complexsimple: '(' complexexp ')' {$$.real=$2.real;$$.img=$2.img;} | '(' CNUMBER ')' {$$.real=$2.real;$$.img=$2.img;} ; /* end: Add your grammar rules and actions here */ %% int main(){ return yyparse(); } int yyerror(const char* s){ printf("%s\n", s); return 0; } /* function provided to do complex addition */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of addition in c3 */ complex complex_add (complex c1, complex c2){ /* c1 + c2 */ complex c3; c3.real = c1.real + c2.real; c3.img = c1.img + c2.img; return c3; } /* function provided to do complex subtraction */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of subtraction in c3 */ complex complex_sub (complex c1, complex c2){ /* c1 - c2 */ complex c3; c3.real = c1.real - c2.real; c3.img = c1.img - c2.img; return c3; } /* function provided to do complex multiplication */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of multiplication in c3 */ complex complex_mul (complex c1, complex c2){ /* c1 * c2 */ complex c3; c3.real = c1.real*c2.real - c1.img*c2.img; c3.img = c1.img*c2.real + c1.real*c2.img; return c3; } /* function provided to do complex division */ /* input : complex numbers c1, c2 */ /* output: nothing */ /* side effect : none */ /* return value: result of c1/c2 in c3 */ complex complex_div (complex c1, complex c2){ /* c1 / c2 (i.e. c1 divided by c2 ) */ complex c3; double d; /*divisor calculation using the conjugate of c2*/ d = c2.real*c2.real + c2.img*c2.img; c3.real = (c1.real*c2.real + c1.img*c2.img)/d; c3.img = (c1.img*c2.real - c1.real*c2.img)/d; return c3; } .h file: #include <string.h> /* struct for holding a complex number */ typedef struct { double real; double img; } complex; /* define the return type of FLEX */ #define YYSTYPE complex Script for compiling the file: bison -d -v complex_cal.y flex -ocomplex_cal.lex.yy.c complex_cal.lex gcc -o complex_cal complex_cal.lex.yy.c complex_cal.tab.c ./complex_cal Some correct sample run of the program: input:(5+6i)*(6+1i) output:24.000000+41.000000i input:(7+8i)/(-3-4i)*(5+7i) output:-11.720000-14.040000i input:(7+8i)/((-3-4i)*(5+7i)) output:-0.128108+0.211351i But when I run this program, the program only give an output which is identical to my input. For example, when I input (5+6i)(6+1i), it just gives (5+6i)(6+1i). Even if I input any other things, for example, input "abc" it just gives "abc" and is not syntax error. I don't know where the problem is and I hope to know how to solve it.

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  • Configuring Oracle HTTP Server 12c for WebLogic Server Domain

    - by Emin Askerov
    Oracle HTTP Server (OHS) 12c 12.1.2 which was released in July 2013 as a part of Oracle Web Tier 12c is the web server component of Oracle Fusion Middleware. In essence this is Apache HTTP Server 2.2.22 (with critical bug fixes from higher versions) which includes modules developed specifically by Oracle. It provides a listener functionality for Oracle WebLogic Server and the framework for hosting static pages, dynamic pages, and applications over the Web. OHS can be easily managed by Weblogic Management Framework, a set of tools which provides administrative capabilities (start, stop, lifecycle operations, etc.) for Oracle Fusion Middleware products. In other words all tools which are familiar to us (Node Manager, WLST, Administration Console, Fusion Middleware Control etc.) presented as a part of Weblogic Management Framework and using for managing Java and System Components both for Weblogic Server and Standalone Domain types. You can familiarize yourself with these terms using related documentation: 1. Introduction to Oracle HTTP Server: http://docs.oracle.com/middleware/1212/webtier/index.html 2. Weblogic Management Framework: http://docs.oracle.com/middleware/1212/core/ASCON/terminology.htm#ASCON11260 In the given post I would like to cover rather simple use case how to configure OHS as web proxy in Weblogic Cluster environment. For example, we have existing Weblogic Domain where some managed servers have been joined to cluster and host business applications. We need to configure web proxy component which will act as entry point, load balancer for our cluster for user requests. Of course, we could install old good Apache HTTP Server and configure mod_wl plugin. However this solution not optimal from manageability perspective: we need to install Apache, install additional plugin then configure it by editing configuration file which is not really convenient for FMW Administrators and often increase time of performing of simple administrative task. Alternatively, we could use OHS as System Component within Weblogic Domain and use full power of Weblogic Management Framework in order to configure, manage and monitor it! I like this idea! What about you? I hope after reading this post you will agree with me. First of all it is necessary to download OHS binaries. You can use this link for downloading: http://www.oracle.com/technetwork/java/webtier/downloads/index2-303202.html As we will use Fusion Middleware Control for managing OHS instances it is necessary to extend your domain with Enterprise Manager and Oracle ADF and JRF templates. This is not topic for focusing in this post, but you could get more information from documentation or one of my previous posts: http://docs.oracle.com/middleware/1212/wls/WLDTR/fmw_templates.htm#sthref64 https://blogs.oracle.com/imc/entry/the_specifics_of_adf_12c Note: you should have properly configured Node Manager utility for managing OHS instances Let’s consider configuration process step by step: 1. Shut down all Weblogic instances of existing domain including Admin Server; 2. Install Oracle HTTP Server. You should use your Fusion Middleware Home Path (e.g. /u01/Oracle/FMW12) for Installation Location and select Colocated HTTP Server option as Installation Type. I will not focus on this topic in this post. All information related to OHS installation you could find here: http://docs.oracle.com/middleware/1212/webtier/WTINS/install_gui.htm#i1082009 3. Next we need to extend our existing domain with OHS component. In order to do this you should do the following: a. Run Fusion Middleware Configuration Wizard (ORACLE_HOME/oracle_common/common/bin/config.sh); b. On the step 1 select Update an existing domain option and point your Fusion Middleware Home Path; c. On the step 2 check Oracle HTTP Server, Oracle Enterprise Manager Plugin for WEBTIER templates; d. Go through other steps without any changes and finish configuration process. 4. Start Admin Server and all managed servers related to your cluster 5. Log in to Enterprise Manager FMW Control using http://<hostname>:<port>/em URL 6. Now we will create OHS instance within our Weblogic Domain Infrastructure. Navigate to Weblogic Domain -> Administration -> Create/Delete OHS menu item; 7. Enter to edit mode, clicking Changes -> Lock&Edit menu item; 8. Create new OHS instance clicking Create button; 9. Define Instance Name (e.g. DevOSH) and Machine parameters; 10. Now we need to define listen port. By default OHS will use 7777 port number for income HTTP requests. We could change it to any free port number we would like to use. In order to do it, right click on our created OHS instance (left hand panel) and navigate to Administration -> Port Configuration; 11. Click on record with port number 7777 and then click Edit button; 12. Change port number value (in our case this will be 8080) and then click OK button; 13. Now we need to edit mod_wl_ohs configuration in order to enable OHS to act as proxy for WebLogic Server Instances/Cluster; 14. In order to do it right click on our created OHS instance (left panel) and navigate to Administration -> mod_wl_ohs Configuration; a. In Weblogic Cluster you should enter cluster address (define <host:port> for all managed servers which participated in cluster), e.g: 192.168.56.2:7004,192.168.56.2:7005 b. Define Weblogic Port parameter at which the Oracle WebLogic Server host is listening for connection requests from the module (or from other servers); c. Check Dynamic Server List option. This will dynamically update cluster list for every request; d. In the Location table define list of endpoint locations which you would like to process. In order to do this click Add Row button and define Location, Weblogic Cluster, Path Trim and Path Prefix parameters (if required); e. Click Apply button in order to save changes. 15. Activate changes clicking Changes ? Activate Changes menu item; 16. Finally we will start configured OHS instance. Right click on OHS instance tree item under Web Tier folder, select Control -> Start Up menu item; 17. Ensure that OHS instance up and running and then test your environment. Run deployed application to your Weblogic Cluster accessing via OHS web proxy; Normal 0 false false false RU X-NONE 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:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

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  • PHP + Code Igniter Timecode Calculation Logic Error

    - by Tim
    Hello everyone, I have what I suspect to be a logic problem with an algorithm I am using to work with Video timecode in PHP. All help is appreciated. The Objective Well basically I want to work with timecode and perform calculations For those not familiar with timecode it looks like this 01:10:58:12 or HH:MM:SS:FF 'AKA' HOURS:MINUTES:SECONDS:FRAMES I have used the script from HERE to help me with working with this format. The Problem Now can i just say that this script works!!! Timecode calculations (in this case additions) are being performed correctly. However this script continually throws the following errors, yet still produces the correct output when I try and do the following calculation 00:01:26:00 + 00:02:00:12 The errors from this calculation are shown below A PHP Error was encountered Severity: Notice Message: Undefined index: key Filename: staff/tools.php Line Number: 169 A PHP Error was encountered Severity: Notice Message: Undefined index: key Filename: staff/tools.php Line Number: 169 Line Number 169 is in the parseInput() function // feed it into the tc array $i=0; foreach ($tc AS $key=>$value) { if ( is_numeric($array["$i"]) ) { $tc["$key"]= $array["$i"]; if ($tc["$key"] < 10 && $tc["$key"] > 0 && strlen($tc['key'])==1 ) $tc["$key"]= "0".$tc["$key"]; } $i++; } return $tc; Now I should also mention that the number of times the above error is thrown depends on what I am calculating 00:00:00:00 + 00:00:00:00 returns no errors. 01:01:01:01 + 02:02:02:02 produces 8 of the above errors. For your reference, here is the code in it's entirety function add_cue_sheet_clips_process() { $sheetID = $_POST['sheet_id']; $clipName = $_POST['clip_name']; $tcIn = $_POST['tc_in']; $tcOut = $_POST['tc_out']; // string $input // returns an associative array of hours, minutes, seconds, and frames // function parseInput ($input) { // timecode should look something like hh:mm:ss;ff // allowed separators are : ; . , // values may be single or double digits // hours are least-significant -- 5.4 == 00:00:05;04 $tc= array("frames"=>"00", "seconds"=>"00", "minutes"=>"00", "hours"=>"00"); $punct= array(":", ";", ".", ","); // too big? too small? $input= trim($input); if (strlen($input)>11 || $input=="") { // invalid input, too long -- bzzt return $tc; } // normalize punctuation $input= str_replace( $punct, ":", $input); // blow it up and reverse it so frames come first $array= explode(":", $input); $array= array_reverse($array); // feed it into the tc array $i=0; foreach ($tc AS $key=>$value) { if ( is_numeric($array["$i"]) ) { $tc["$key"]= $array["$i"]; if ($tc["$key"] < 10 && $tc["$key"] > 0 && strlen($tc['key'])==1 ) $tc["$key"]= "0".$tc["$key"]; } $i++; } return $tc; } // array $tc // returns a float number of seconds // function tcToSec($tc) { $wholeseconds= ($tc['hours']*3600) + ($tc['minutes'] * 60) + ($tc['seconds']); $partseconds= ( $tc['frames'] / 25 ); $seconds= $wholeseconds + $partseconds; return $seconds; } // float $seconds // bool $subtract // returns a timecode array // function secToTc ($seconds=0, $subtract=0) { $tc= array("frames"=>"00", "seconds"=>"00", "minutes"=>"00", "hours"=>"00"); $partseconds= fmod($seconds, 1); $wholeseconds= $seconds - $partseconds; // frames if ($subtract==1) $tc['frames']= floor( $partseconds * 25 ); else $tc['frames']= floor( $partseconds * 25 ); // hours $tc['hours']= floor( $wholeseconds / 3600 ); $minsec= ($wholeseconds - ($tc['hours'] * 3600)); // minutes $tc['minutes']= floor( $minsec / 60 ); // seconds $tc['seconds']= ( $minsec - ($tc['minutes'] * 60) ); // padding foreach ( $tc AS $key=>$value ) { if ($value > 0 && $value < 10) $tc["$key"]= "0".$value; if ($value=="0") $tc["$key"]= "00"; } return $tc; } // array $tc // returns string of well-formed timecode // function tcToString (&$tc) { return $tc['hours'].":".$tc['minutes'].":".$tc['seconds'].";".$tc['frames']; } $timecodeIN = parseInput($tcIn); $timecodeOUT = parseInput($tcOut); // normalized inputs... $tc1 = tcToString($timecodeIN); $tc2 = tcToString($timecodeOUT); // get seconds $seconds1 = tcToSec($timecodeIN); $seconds2 = tcToSec($timecodeOUT); $result = $seconds1 + $seconds2; $timecode3 = secToTc($result, 0); $timecodeDUR = tcToString($timecode3); $clipArray = array('clip_name' => $clipName, 'tc_in' => $tcIn, 'tc_out' => $tcOut, 'tc_duration' => $timecodeDUR); $this->db->insert('tools_cue_sheets_clips', $clipArray); redirect('staff/tools/add_cue_sheet_clips/'.$sheetID); } I hope this is enough information for someone to help me get on top of this, I would be extremely greatful. Thanks, Tim

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  • Benchmarking MySQL Replication with Multi-Threaded Slaves

    - by Mat Keep
    0 0 1 1145 6530 Homework 54 15 7660 14.0 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:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; 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; mso-ansi-language:EN-US;} The objective of this benchmark is to measure the performance improvement achieved when enabling the Multi-Threaded Slave enhancement delivered as a part MySQL 5.6. As the results demonstrate, Multi-Threaded Slaves delivers 5x higher replication performance based on a configuration with 10 databases/schemas. For real-world deployments, higher replication performance directly translates to: · Improved consistency of reads from slaves (i.e. reduced risk of reading "stale" data) · Reduced risk of data loss should the master fail before replicating all events in its binary log (binlog) The multi-threaded slave splits processing between worker threads based on schema, allowing updates to be applied in parallel, rather than sequentially. This delivers benefits to those workloads that isolate application data using databases - e.g. multi-tenant systems deployed in cloud environments. Multi-Threaded Slaves are just one of many enhancements to replication previewed as part of the MySQL 5.6 Development Release, which include: · Global Transaction Identifiers coupled with MySQL utilities for automatic failover / switchover and slave promotion · Crash Safe Slaves and Binlog · Optimized Row Based Replication · Replication Event Checksums · Time Delayed Replication These and many more are discussed in the “MySQL 5.6 Replication: Enabling the Next Generation of Web & Cloud Services” Developer Zone article  Back to the benchmark - details are as follows. Environment The test environment consisted of two Linux servers: · one running the replication master · one running the replication slave. Only the slave was involved in the actual measurements, and was based on the following configuration: - Hardware: Oracle Sun Fire X4170 M2 Server - CPU: 2 sockets, 6 cores with hyper-threading, 2930 MHz. - OS: 64-bit Oracle Enterprise Linux 6.1 - Memory: 48 GB Test Procedure Initial Setup: Two MySQL servers were started on two different hosts, configured as replication master and slave. 10 sysbench schemas were created, each with a single table: CREATE TABLE `sbtest` (    `id` int(10) unsigned NOT NULL AUTO_INCREMENT,    `k` int(10) unsigned NOT NULL DEFAULT '0',    `c` char(120) NOT NULL DEFAULT '',    `pad` char(60) NOT NULL DEFAULT '',    PRIMARY KEY (`id`),    KEY `k` (`k`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 10,000 rows were inserted in each of the 10 tables, for a total of 100,000 rows. When the inserts had replicated to the slave, the slave threads were stopped. The slave data directory was copied to a backup location and the slave threads position in the master binlog noted. 10 sysbench clients, each configured with 10 threads, were spawned at the same time to generate a random schema load against each of the 10 schemas on the master. Each sysbench client executed 10,000 "update key" statements: UPDATE sbtest set k=k+1 WHERE id = <random row> In total, this generated 100,000 update statements to later replicate during the test itself. Test Methodology: The number of slave workers to test with was configured using: SET GLOBAL slave_parallel_workers=<workers> Then the slave IO thread was started and the test waited for all the update queries to be copied over to the relay log on the slave. The benchmark clock was started and then the slave SQL thread was started. The test waited for the slave SQL thread to finish executing the 100k update queries, doing "select master_pos_wait()". When master_pos_wait() returned, the benchmark clock was stopped and the duration calculated. The calculated duration from the benchmark clock should be close to the time it took for the SQL thread to execute the 100,000 update queries. The 100k queries divided by this duration gave the benchmark metric, reported as Queries Per Second (QPS). Test Reset: The test-reset cycle was implemented as follows: · the slave was stopped · the slave data directory replaced with the previous backup · the slave restarted with the slave threads replication pointer repositioned to the point before the update queries in the binlog. The test could then be repeated with identical set of queries but a different number of slave worker threads, enabling a fair comparison. The Test-Reset cycle was repeated 3 times for 0-24 number of workers and the QPS metric calculated and averaged for each worker count. MySQL Configuration The relevant configuration settings used for MySQL are as follows: binlog-format=STATEMENT relay-log-info-repository=TABLE master-info-repository=TABLE As described in the test procedure, the slave_parallel_workers setting was modified as part of the test logic. The consequence of changing this setting is: 0 worker threads:    - current (i.e. single threaded) sequential mode    - 1 x IO thread and 1 x SQL thread    - SQL thread both reads and executes the events 1 worker thread:    - sequential mode    - 1 x IO thread, 1 x Coordinator SQL thread and 1 x Worker thread    - coordinator reads the event and hands it to the worker who executes 2+ worker threads:    - parallel execution    - 1 x IO thread, 1 x Coordinator SQL thread and 2+ Worker threads    - coordinator reads events and hands them to the workers who execute them Results Figure 1 below shows that Multi-Threaded Slaves deliver ~5x higher replication performance when configured with 10 worker threads, with the load evenly distributed across our 10 x schemas. This result is compared to the current replication implementation which is based on a single SQL thread only (i.e. zero worker threads). Figure 1: 5x Higher Performance with Multi-Threaded Slaves The following figure shows more detailed results, with QPS sampled and reported as the worker threads are incremented. The raw numbers behind this graph are reported in the Appendix section of this post. Figure 2: Detailed Results As the results above show, the configuration does not scale noticably from 5 to 9 worker threads. When configured with 10 worker threads however, scalability increases significantly. The conclusion therefore is that it is desirable to configure the same number of worker threads as schemas. Other conclusions from the results: · Running with 1 worker compared to zero workers just introduces overhead without the benefit of parallel execution. · As expected, having more workers than schemas adds no visible benefit. Aside from what is shown in the results above, testing also demonstrated that the following settings had a very positive effect on slave performance: relay-log-info-repository=TABLE master-info-repository=TABLE For 5+ workers, it was up to 2.3 times as fast to run with TABLE compared to FILE. Conclusion As the results demonstrate, Multi-Threaded Slaves deliver significant performance increases to MySQL replication when handling multiple schemas. This, and the other replication enhancements introduced in MySQL 5.6 are fully available for you to download and evaluate now from the MySQL Developer site (select Development Release tab). You can learn more about MySQL 5.6 from the documentation  Please don’t hesitate to comment on this or other replication blogs with feedback and questions. Appendix – Detailed Results

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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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  • winForms Booking Class Help

    - by cameron
    Hi, I am using C# Windows Forms in visual studio with different classes performing different functions in my program. I have a "Program" main class with the following information: static class Program { /// <summary> /// The main entry point for the application. /// </summary> [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } } and a Screen class with the following information class Screen { public List<Show> shows { get; private set; } public int ScreenNumber { get; private set; } public Screen(int screenNumber, params Show[] schedule) { this.ScreenNumber = screenNumber; this.shows = schedule.ToList<Show>(); } } and a Seat class with the following information public class Seat { private string name; public bool IsAvailable { get; set; } public decimal Price { get; private set; } public int Number { get; private set; } public Seat(bool isAvailable, int number) { this.IsAvailable = isAvailable; this.name = String.Format("Seat {0}",number); this.Price = 7.50m; this.Number = number; } public override string ToString() { return this.name; } } and finally a Show class with the following information public class Show { private List<Seat> seats = new List<Seat>(); public string Title { get; private set; } public string Time { get; private set; } public int ScreenNumber { get; private set; } public List<Seat> Seats { get { return this.seats; } } public Show(string title, DateTime time, int screenNumber, int numberOfSeats) { this.Title = title; this.Time = time.ToShortTimeString(); this.ScreenNumber = screenNumber; this.initSeats(numberOfSeats); } private void initSeats(int numberOfSeats) { for (int i = 0; i < numberOfSeats; i++) this.seats.Add(new Seat(true, i + 1)); } }` these all feed into two different winForms to create a booking system for shows. therefore i need to collate the data given in program and output it into a txt file. any help will be much appreciated NOTE: the code for FORM1 which allows the user to select which show they want is: namespace CindysSeats { public partial class Form1 : Form { private Cinema cinema = new Cinema(); //booked show could be added to booking object when you create it so that it is easily writable to the external file private Show selectedShow; public Form1() { InitializeComponent(); this.showList_dg.DataSource = this.cinema.GetShowList(); } private void showList_dg_RowHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e) { Show selectedShow = this.selectedShow = this.cinema.GetShowList()[e.RowIndex]; this.showTitle_lbl.Text = selectedShow.Title; this.showTime_lbl.Text = selectedShow.Time; this.showScreen_lbl.Text = selectedShow.ScreenNumber.ToString(); } private void confirmShow_btn_Click(object sender, EventArgs e) { if (this.selectedShow == null) return; Form2 seats = new Form2(this.selectedShow); seats.Show(); } And the code for FORM2 which is where the user selects their seats they want is: namespace CindysSeats { public partial class Form2 : Form { //booked seats could be added to booking object when you create it so that it is easily writable to the external file private List<Seat> bookedSeats = new List<Seat>(); private Show selectedShow; public Form2(Show selectedShow) { InitializeComponent(); this.selectedShow = selectedShow; this.showSeats_dg.DataSource = this.selectedShow.Seats; } private void showSeats_dg_RowHeaderMouseClick(object sender, DataGridViewCellMouseEventArgs e) { Seat selectedSeat = this.selectedShow.Seats[e.RowIndex]; if(this.bookedSeats.Contains(selectedSeat)) return; if(!selectedSeat.IsAvailable) return; this.bookedSeats.Add(selectedSeat); this.bookedSeats_lv.Items.Add(selectedSeat.ToString() + " " + selectedSeat.Price.ToString()+"\n"); this.bookedSeats_lv.Invalidate(); } private void bookSeats_btn_Click(object sender, EventArgs e) { } } thank you for helping

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  • PASS: The Budget Process

    - by Bill Graziano
    Every fiscal year PASS creates a detailed budget.  This helps us set priorities and communicate to our members what we’re going to do in the upcoming year.  You can review the current budget on the PASS Governance page.  That page currently requires you to login but I’m talking with HQ to see if there are any legal issues with opening that up. The Accounting Team The PASS accounting team is two people.  The Executive Vice-President of Finance (“EVP”) and the PASS Accounting Manager.  Sandy Cherry is the accounting manager and works at PASS HQ.  Sandy has been with PASS since we switched management companies in 2007.  Throughout this document when I talk about any actual work related to the budget that’s all Sandy :)  She’s the glue that gets us through this process.  Last year we went through 32 iterations of the budget before the Board approved so it’s a pretty busy time for her us – well, mostly her. Fiscal Year The PASS fiscal year runs from July 1st through June 30th the following year.  Right now we’re in fiscal year 2011.  Our 2010 Summit actually occurred in FY2011.  We switched to this schedule from a calendar year in 2006.  Our goal was to have the Summit occur early in our fiscal year.  That gives us the rest of the year to handle any significant financial impact from the Summit.  If registrations are down we can reduce spending.  If registrations are up we can decide how much to increase our reserves and how much to spend.  Keep in mind that the Summit is budgeted to generate 82% of our revenue this year.  How it performs has a significant impact on our financials.  The other benefit of this fiscal year is that it matches the Microsoft fiscal year.  We sign an annual sponsorship agreement with Microsoft and it’s very helpful that our fiscal years match. This year our budget process will probably start in earnest in March or April.  I’d like to be done in early June so we can publish before July 1st.  I was late publishing it this year and I’m trying not to repeat that. Our Budget Our actual budget is an Excel spreadsheet with 36 sheets.  We remove some of those when we publish it since they include salary information.  The budget is broken up into various portfolios or departments.  We have 20 portfolios.  They include chapters, marketing, virtual chapters, marketing, etc.  Ideally each portfolio is assigned to a Board member.  Each portfolio also typically has a staff person assigned to it.  Portfolios that aren’t assigned to a Board member are monitored by HQ and the ExecVP-Finance (me).  These are typically smaller portfolios such as deferred membership or Summit futures.  (More on those in a later post.)  All portfolios are reviewed by all Board members during the budget approval process, when interim financials are released internally and at year-end. The Process Our first step is to budget revenues.  The Board determines a target attendee number.  We have formulas based on historical performance that convert that to an overall attendee revenue number.  Other revenue projections (such as vendor sponsorships) come from different parts of the organization.  I hope to have another post with more details on how we project revenues. The next step is to budget expenses.  Board members fill out a sample spreadsheet with their budget for the year.  They can add line items and notes describing what the amounts are for.  Each Board portfolio typically has from 10 to 30 line items.  Any new initiatives they want to pursue needs to be budgeted.  The Summit operations budget is managed by HQ.  It includes the cost for food, electrical, internet, etc.  Most of these come from our estimate of attendees and our contract with the convention center.  During this process the Board can ask for more or less to be spent on various line items.  For example, if we weren’t happy with the Internet at the last Summit we can ask them to look into different options and/or increasing the budget.  HQ will also make adjustments to these numbers based on what they see at the events and the feedback we receive on the surveys. After we have all the initial estimates we start reviewing the entire budget.  It is sent out to the Board and we can see what each portfolio requested and what the overall profit and loss number is.  We usually start with too much in expenses and need to cut.  In years past the Board started haggling over these numbers as a group.  This past year they decided I should take a first cut and present them with a reasonable budget and a list of what I changed.  That worked well and I think we’ll continue to do that in the future. We go through a number of iterations on the budget.  If I remember correctly, we went through 32 iterations before we passed the budget.  At each iteration various revenue and expense numbers can change.  Keep in mind that the PASS budget has 200+ line items spread over 20 portfolios.  Many of these depend on other numbers.  For example, if we decide increase the projected attendees that cascades through our budget.  At each iteration we list what changed and the impact.  Ideally these discussions will take place at a face-to-face Board meeting.  Many of them also take place over the phone.  Board members explain any increase they are asking for while performing due diligence on other budget requests.  Eventually a budget emerges and is passed. Publishing After the budget is passed we create a version without the formulas and salaries for posting on the web site.  Sandy also creates some charts to help our members understand the budget.  The EVP writes a nice little letter describing some of the changes from last year’s budget.  You can see my letter and our budget on the PASS Governance page. And then, eight months later, we start all over again.

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  • Scheduling thread tiles with C++ AMP

    - by Daniel Moth
    This post assumes you are totally comfortable with, what some of us call, the simple model of C++ AMP, i.e. you could write your own matrix multiplication. We are now ready to explore the tiled model, which builds on top of the non-tiled one. Tiling the extent We know that when we pass a grid (which is just an extent under the covers) to the parallel_for_each call, it determines the number of threads to schedule and their index values (including dimensionality). For the single-, two-, and three- dimensional cases you can go a step further and subdivide the threads into what we call tiles of threads (others may call them thread groups). So here is a single-dimensional example: extent<1> e(20); // 20 units in a single dimension with indices from 0-19 grid<1> g(e);      // same as extent tiled_grid<4> tg = g.tile<4>(); …on the 3rd line we subdivided the single-dimensional space into 5 single-dimensional tiles each having 4 elements, and we captured that result in a concurrency::tiled_grid (a new class in amp.h). Let's move on swiftly to another example, in pictures, this time 2-dimensional: So we start on the left with a grid of a 2-dimensional extent which has 8*6=48 threads. We then have two different examples of tiling. In the first case, in the middle, we subdivide the 48 threads into tiles where each has 4*3=12 threads, hence we have 2*2=4 tiles. In the second example, on the right, we subdivide the original input into tiles where each has 2*2=4 threads, hence we have 4*3=12 tiles. Notice how you can play with the tile size and achieve different number of tiles. The numbers you pick must be such that the original total number of threads (in our example 48), remains the same, and every tile must have the same size. Of course, you still have no clue why you would do that, but stick with me. First, we should see how we can use this tiled_grid, since the parallel_for_each function that we know expects a grid. Tiled parallel_for_each and tiled_index It turns out that we have additional overloads of parallel_for_each that accept a tiled_grid instead of a grid. However, those overloads, also expect that the lambda you pass in accepts a concurrency::tiled_index (new in amp.h), not an index<N>. So how is a tiled_index different to an index? A tiled_index object, can have only 1 or 2 or 3 dimensions (matching exactly the tiled_grid), and consists of 4 index objects that are accessible via properties: global, local, tile_origin, and tile. The global index is the same as the index we know and love: the global thread ID. The local index is the local thread ID within the tile. The tile_origin index returns the global index of the thread that is at position 0,0 of this tile, and the tile index is the position of the tile in relation to the overall grid. Confused? Here is an example accompanied by a picture that hopefully clarifies things: array_view<int, 2> data(8, 6, p_my_data); parallel_for_each(data.grid.tile<2,2>(), [=] (tiled_index<2,2> t_idx) restrict(direct3d) { /* todo */ }); Given the code above and the picture on the right, what are the values of each of the 4 index objects that the t_idx variables exposes, when the lambda is executed by T (highlighted in the picture on the right)? If you can't work it out yourselves, the solution follows: t_idx.global       = index<2> (6,3) t_idx.local          = index<2> (0,1) t_idx.tile_origin = index<2> (6,2) t_idx.tile             = index<2> (3,1) Don't move on until you are comfortable with this… the picture really helps, so use it. Tiled Matrix Multiplication Example – part 1 Let's paste here the C++ AMP matrix multiplication example, bolding the lines we are going to change (can you guess what the changes will be?) 01: void MatrixMultiplyTiled_Part1(vector<float>& vC, const vector<float>& vA, const vector<float>& vB, int M, int N, int W) 02: { 03: 04: array_view<const float,2> a(M, W, vA); 05: array_view<const float,2> b(W, N, vB); 06: array_view<writeonly<float>,2> c(M, N, vC); 07: parallel_for_each(c.grid, 08: [=](index<2> idx) restrict(direct3d) { 09: 10: int row = idx[0]; int col = idx[1]; 11: float sum = 0.0f; 12: for(int i = 0; i < W; i++) 13: sum += a(row, i) * b(i, col); 14: c[idx] = sum; 15: }); 16: } To turn this into a tiled example, first we need to decide our tile size. Let's say we want each tile to be 16*16 (which assumes that we'll have at least 256 threads to process, and that c.grid.extent.size() is divisible by 256, and moreover that c.grid.extent[0] and c.grid.extent[1] are divisible by 16). So we insert at line 03 the tile size (which must be a compile time constant). 03: static const int TS = 16; ...then we need to tile the grid to have tiles where each one has 16*16 threads, so we change line 07 to be as follows 07: parallel_for_each(c.grid.tile<TS,TS>(), ...that means that our index now has to be a tiled_index with the same characteristics as the tiled_grid, so we change line 08 08: [=](tiled_index<TS, TS> t_idx) restrict(direct3d) { ...which means, without changing our core algorithm, we need to be using the global index that the tiled_index gives us access to, so we insert line 09 as follows 09: index<2> idx = t_idx.global; ...and now this code just works and it is tiled! Closing thoughts on part 1 The process we followed just shows the mechanical transformation that can take place from the simple model to the tiled model (think of this as step 1). In fact, when we wrote the matrix multiplication example originally, the compiler was doing this mechanical transformation under the covers for us (and it has additional smarts to deal with the cases where the total number of threads scheduled cannot be divisible by the tile size). The point is that the thread scheduling is always tiled, even when you use the non-tiled model. But with this mechanical transformation, we haven't gained anything… Hint: our goal with explicitly using the tiled model is to gain even more performance. In the next post, we'll evolve this further (beyond what the compiler can automatically do for us, in this first release), so you can see the full usage of the tiled model and its benefits… Comments about this post by Daniel Moth welcome at the original blog.

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  • What could be causing frequent display freezes?

    - by austen
    I just installed Ubuntu 14.04 two days ago (coming from Win8) and in the two days that I've been using it, my display has frozen four or five times. The mouse won't move but the keyboard does respond so I can use the Ctrl+Alt+Bkspc command to fix it. It seems like it might just be the display freezing because one of the times I was watching a Youtube video and the audio continued playing. I have an Nvidia graphics card with the most recent Nvidia drivers for it enabled. I see that a lot of questions about Ubuntu freezing get marked as a duplicate and pretty much always linked back to a thread about what to do when it freezes. Clearly, I've got that bit figured out already and I did read that thread for further advice. What I'm looking for though is how to fix this permanently. output from lspci -nnk | grep -iA2 VGA: 00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core processor Graphics Controller [8086:0166] (rev 09) Subsystem: Lenovo Device [17aa:2200] Kernel driver in use: i915 Update: JohnnyEnglish pointed out that Ubuntu is using the integrated graphics, not my Nvidia card. It turns out my laptop uses Nvidia Optimus and I cannot enable only the graphics card through the BIOS. I found out about Nvidia Prime and got it set up using this article. The settings panel which allows you to select the graphics says that 'performance mode' is enabled but when I check which graphics controller is enabled through the terminal, it still says it's using the integrated graphics. I'm not sure if this could be causing the freezes but I guess it's a starting point. Any ideas on how to resolve this?

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  • Installing nvidia drivers causes computer to boot to command prompt.

    - by levesque
    Hi, I have an Asus u30jc laptop, which comes with the Optimus prime graphics card switching technology that is now supported under 2.6.35, so I decided to give it a try. First I made sure the discrete graphics card was activated and then I installed the drivers proposed by the ubuntu software repository (nvidia-current). However, after rebooting all I got was a command prompt. My graphics card is a nvidia 310M. This is on Ubuntu 10.10 64 bits. What can I do to diagnose/identify the source of this problem? UPDATE: The messsages in my syslog tell me to check the xorg log: Oct 11 12:42:59 u30jc-test gdm-binary[1095]: WARNING: GdmDisplay: display lasted 0.053144 seconds Oct 11 12:42:59 u30jc-test gdm-simple-slave[1450]: WARNING: Unable to load file '/etc/gdm/custom.conf': No such file or directory Oct 11 12:42:59 u30jc-test gdm-binary[1095]: WARNING: GdmDisplay: display lasted 0.038176 seconds Oct 11 12:42:59 u30jc-test gdm-binary[1095]: WARNING: GdmLocalDisplayFactory: maximum number of X display failures reached: check X server log for errors Which I did. I found this message in my /var/log/Xorg.0.log : Fatal server error: [ 113.540] no screens found [ 113.540] What does that mean?

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  • Ubuntu Gnome 14.04 Instal Nvidia drivers

    - by user3524668
    I have been looking all over the web, and tried every suggestion I found to get the nvidia drivers working on my computer with Ubuntu Gnome 14.04, with no luck. Every time I install a driver or choose to use the driver from addition drivers, when I reebot, I cannot log in again. It gets stuck at the logo screen. I need to go to the ALT + CTRL + F1 to purge all nvidia traces so I can get back. Is it possible to install the new nvidia drivers? I just upgraded from 13.10 to 14.04, I have an Asus N550VJ which has hybrid graphics with Intel 4000 / Nvidia 750M What Im looking for is to try the primus functionality to disable the discreet card and enable it whenever I want to play or run heavy graphic stuff. When I was in 13.10 I was using bumblebee, but, since, the nvidia prime is supposedly mature enough, I wanted to try it. Is this possible for Ubuntu Gnome 14.04. I read there was a bug with gdm, but also, saw that it was already fixed. Thank you very much for your help. Im not that well versed in linux.

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