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• Why is my laptop so sluggish? Or Damn You Facebook and Twitter! Or All Hail Chrome!

  - by John Conwell

  In the past three weeks, I've noticed that my laptop (dual core 2.1GHz, 2Gb RAM) has become amazingly sluggish.  I only uses for communications and data lookup workflows, so the slowness was tolerable.  But today I finally got fed up with the suckyness and decided to get to the root of the problem (I do have strong performance roots after all). It actually didn't take all that long to figure it out.  About a year ago I converted to Google Chrome (away from FireFox).  One of the great tools Chrome has is a "Task Manager" tool, that gives you Windows Task Manager like details for all the tabs open in the browser (Shift + Esc).  Since every tab runs in its own process, its easy from Task Manager (both Windows or Chrome) to identify and kill a single performance offending tab.  This is unlike IE, where you only get aggregate data about all tabs open.  Anyway, I digress.  Today my laptop sucked.  Windows Task Manager told me that I had two memory hogging Chrome tabs, but couldn't tell me which web page those tabs are showing.  Enter Chrome Task Manager which tells you the page title, along with CPU, memory and network utilization of each tab.  Enter my amazement.  Turns out Facebook was using just shy of half a Gb of RAM.  Half a Gigabyte!  That's 512 Megabytes!524,288 Kilobytes! 536,870,912 Bytes!  Or 4,294,967,296 Bits!  In other words, that's a frackin boat load of memory.  Now consider that Facebook is running on pretty much 96.3% (statistics based on absolutely nothing) of every house hold desktop, laptop, netbook, and mobile device in America, that is pretty horrific! And I wasn't playing any Facebook games like FarmWars or MafiaVille.  I just had my normal, default home page up showing me who just had breakfast, or just got finished with their morning run. I'm sorry...let me say that again...HALF A GIG OF RAM!  That is just unforgivable. I can just see my mom calling me up:  Mom: "John...I think I need a new computer.  Mine is really slow these days" John: "What do you have running?" Mom: "Oh, just Facebook" John: "Ok, close Facebook and tell me how fast your computer feels" Mom: "Well...I don't know how fast it is.  All I do is use Facebook" John: "Ok Mom, I'll send you a new computer by Tuesday" Oh yea...and the other offending web page?  It was Twitter, using a quarter of a Gigabyte. God I love social networks!

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• VS2010 Launch Presentations

  Last week I was in Vegas to present at the DevConnections / VS2010 Launch event.  The show was well-attended and everybody I spoke to agreed it was educational and enjoyable.  My three talks were all on Wednesday, 14 April 2010, including one at 8am for which I was impressed to see a large turnout in attendance.   Pragmatic ASP.NET Tips, Tricks, and Tools My first session was on tips, tricks, and tools for ASP.NET developers.  This is a talk Ive given in past years, but which I refine every time.  I usually like to have a full session to devote to tools, and a separate talk just for Tips and Tricks, but for this show I was only given the one 75-minute slot, so I had to cut some materials to make things fit.  The talk went well, all the demos work, and the attendees seemed to enjoy it, and I like giving it, so hopefully I can continue to present on this topic in future DevConnections shows. Download the ASP.NET Tips, Tricks, and Tools slides and demos.   Whats New in ASP.NET MVC 2 My second talk of the day followed immediately after the Tips and Tricks talk, and was a brand new talk for me.  I have to throw out a thank-you to Phil for letting me see his MIX slide deck before he gave his talk, as that was a big help.  The official whats new document online is also worth checking out if youre interested in this subject.  Download the Whats New in ASP.NET MVC 2 slides and demos.   SOLIDify Your ASP.NET MVC 2 Application Just because youre using a ASP.NET MVC doesnt mean your code cant still end up being a big ball of mud.  This session describes a number of principles of software design that can help ensure applications remain loosely-coupled and malleable even as they age and increase in features and complexity.  This was my last talk of the day and did have one minor demo failure involving a database constraint.  Ive given this talk many times before, and in this case I had to fit it into a 60-minute timeslot, so Im not sure I had quite enough time to drive home all of the concepts to everyone in the audience.  That said, I did hear a number of positive comments on how the talk went, so thats encouraging. Download the SOLIDify Your ASP.NET MVC 2 Application slides and demos.   In my sessions, I promised to have these posted by the end of the weekend theyre going up at 10pm Sunday night (my time) 2 hours to spare!  Enjoy! Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• How to export 3D models that consist of several parts (eg. turret on a tank)?

  - by Will

  What are the standard alternatives for the mechanics of attaching turrets and such to 3D models for use in-game? I don't mean the logic, but rather the graphics aspects. My naive approach is to extend the MD2-like format that I'm using (blender-exported using a script) to include a new set of properties for a mesh that: is anchored in another 'parent' mesh. The anchor is a point and normal in the parent mesh and a point and normal in the child mesh; these will always be colinear, giving the child rotation but not translation relative to the parent point. has a normal that is aligned with a 'target'. Classically this target is the enemy that is being engaged, but it might be some other vector e.g. 'the wind' (for sails and flags (and smoke, which is a particle system but the same principle applies)) or 'upwards' (e.g. so bodies of riders bend properly when riding a horse up an incline etc). that the anchor and target alignments have maximum and minimum and a speed coeff. there is game logic for multiple turrets and on a model and deciding which engages which enemy. 'primary' and 'secondary' or 'target0' ... 'targetN' or some such annotation will be there. So to illustrate, a classic tank would be made from three meshes; a main body mesh, a turret mesh that is anchored to the top of the main body so it can spin only horizontally and a barrel mesh that is anchored to the front of the turret and can only move vertically within some bounds. And there might be a forth flag mesh on top of the turret that is aligned with 'wind' where wind is a function the engine solves that merges environment's wind angle with angle the vehicle is travelling in an velocity, or something fancy. This gives each mesh one degree of freedom relative to its parent. Things with multiple degrees of freedom can be modelled by zero-vertex connecting meshes perhaps? This is where I think the approach I outlined begins to feel inelegant, yet perhaps its still a workable system? This is why I want to know how it is done in professional games ;) Are there better approaches? Are there formats that already include this information? Is this routine?

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• Design pattern to handle queries using multiple models

  - by coderkane

  I am presented with a dilemma while trying to re-designing the class structure for my PHP/MySQL application to make it more elegant and conform it to the SOLID principle. The problem goes like this: Let as assume, there is an abstract class called person which has certain properties to define a generic person, such as name, age, date of birth etc. There are two classes, student, and teacher, that implements this abstract class. They add their own unique properties to it. I have designed all the three classes to include all the operational logic (details of which are not relevant in context of the question). Now, I need to create views/reports/data grids which contain details from multiple classes, for example, say, a list of all students doing projects in Chemistry mentored by a teacher whose name is the parameter to the query. This is just one example of a view, there are many different views in the application, which uses data from 3-4 tables, and each of them have multiple input parameters to generate them. Considering this particular example, I have written the relevant query using JOIN and the results are as expected and proper, now here is the dilemma: Keeping in mind the single responsibility principle, where should I keep this query? It does not belong to either Student class, or Teacher class or any other classes currently present. a) Should I create a new class, say dataView class, and design it as a MVC pattern and keep the query there? What about the other views? how do they fit in this architecture? b) Should I not keep the query in code at all, and make it DB View ? c) Am I completely wrong in the approach? If so what is the right approach? My considerations are as follows: a) should be easy to add new views later on if requirement comes, without having to copy-paste-modify code b) would like to make it as loosely coupled as possible so that if minor db structure changes happen, it does not break I did google searches on report design and OOP report generators, but all the result seem to focus on the visual design of the report rather than fetching the data. I have already taken care of the visual aspect of the report using MVC with html templates. I am sure this is a very fundamental problem with known solution, but I am somehow not able to find it (maybe searching with wrong keyword). Edit1: Modified the title to make it more relevant Edit2: The accepted answer got me thinking in the right direction and identify my design flaws, which eventually led me to find this question and the solution in Stack Overflow which gave me the detailed answer to clear the confusion.

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• Java EE 8 update

  - by delabassee

  Planning for Java EE 8 is now well underway. As you know, a few weeks ago, we conducted a three part Java EE 8 Community Survey (you can find the final summary here). The data gathered have been very influential for the next steps. You can now expect over the coming weeks and months to see updates on the various specifications that compose the Java EE platform. Some Specification Leads are busy gathering additional feedback regarding what they should focus their efforts on (e.g. CDI 2 survey). Other Specification Leads have already publicly exposed what they think should be one of the focus for the evolution of the specification they lead.  For example, adding Server-Senet Events (SSE) support in JAX-RS is being discussed here and adding MVC support is being discussed here. Please remember that the fact we are now discussing any feature does not insure that it will be included in the proposal, nor in any particular update to Java EE. We can expect additional enhancements, changes and evolutions as we get closer to the finalisation of the different specifications... and there is still a long way to go with these specification proposals! Linda DeMichiel, Java EE Co-Specification Lead, has recently posted a draft proposal for the Java EE 8 Platform specification. Linda's goal is to recruit people and companies supporting this proposal before submitting it to the JCP.  This draft proposal is very interesting reading as it contains relevant information on the plans for Java EE 8 such as : The themes: Support for the latest web standards (eg. HTTP 2.0)  Continue to work on ease of development Improve the infrastructure for cloud support Alignment with Java SE 8 New JSRs to be added to the platform: J-Cache Java API for JSON Binding Java Configuration Plans for the Web Profile Plans on technologies to prune in Java EE 8, ... So if you haven't done it yet, I really encourage you to read the Java EE 8 draft proposal! Our goal for the Java EE 8 specification is for it to be finalized in the second half of 2016. It is important to note that we are in the early days of Java EE 8 and at this stage everything (themes, content, timing, etc.) is preliminary. Everything still needs to be discussed, challenged and agreed within the different Java Community Process (JCP) Experts Groups (EGs). Some EGs that still need to be formed! It could also means that the roadmap will have to be adjusted to follow the progress being made in the different EGs. This is also a good occasion to remind you that participation within those upcoming JCP Experts Groups is encouraged. Contributing in an EG is an effective lever to influence what Java EE 8 will become! Finally, as things get more concrete, we will share details on how to engage in the different Java EE 8 related Adopt-a-JSR initiatives, another way to contribute. You can also read other posts related to Java EE 8, here at The Aquarium blog. Just look for articles with the 'javaee8' tag.

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• Incorrect results for frustum cull

  - by DeadMG

  Previously, I had a problem with my frustum culling producing too optimistic results- that is, including many objects that were not in the view volume. Now I have refactored that code and produced a cull that should be accurate to the actual frustum, instead of an axis-aligned box approximation. The problem is that now it never returns anything to be in the view volume. As the mathematical support library I'm using does not provide plane support functions, I had to code much of this functionality myself, and I'm not really the mathematical type, so it's likely that I've made some silly error somewhere. As follows is the relevant code: class Plane { public: Plane() { r0 = Math::Vector(0,0,0); normal = Math::Vector(0,1,0); } Plane(Math::Vector p1, Math::Vector p2, Math::Vector p3) { r0 = p1; normal = Math::Cross((p2 - p1), (p3 - p1)); } Math::Vector r0; Math::Vector normal; }; This class represents one plane as a point and a normal vector. class Frustum { public: Frustum( const std::array<Math::Vector, 8>& points ) { planes[0] = Plane(points[0], points[1], points[2]); planes[1] = Plane(points[4], points[5], points[6]); planes[2] = Plane(points[0], points[1], points[4]); planes[3] = Plane(points[2], points[3], points[6]); planes[4] = Plane(points[0], points[2], points[4]); planes[5] = Plane(points[1], points[3], points[5]); } Plane planes[6]; }; The points are passed in order where (the inverse of) each bit of the index of each point indicates whether it's the left, top, and back of the frustum, respectively. As such, I just picked any three points where they all shared one bit in common to define the planes. My intersection test is as follows (based on this): bool Intersects(Math::AABB lhs, const Frustum& rhs) const { for(int i = 0; i < 6; i++) { Math::Vector pvertex = lhs.TopRightFurthest; Math::Vector nvertex = lhs.BottomLeftClosest; if (rhs.planes[i].normal.x <= -0.0f) { std::swap(pvertex.x, nvertex.x); } if (rhs.planes[i].normal.y <= -0.0f) { std::swap(pvertex.y, nvertex.y); } if (rhs.planes[i].normal.z <= -0.0f) { std::swap(pvertex.z, nvertex.z); } if (Math::Dot(rhs.planes[i].r0, nvertex) < 0.0f) { return false; } } return true; } Also of note is that because I'm using a left-handed co-ordinate system, I wrote my Cross function to return the negative of the formula given on Wikipedia. Any suggestions as to where I've made a mistake?

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• How can a single disk in a hardware SATA RAID-10 array bring the entire array to a screeching halt?

  - by Stu Thompson

  Prelude: I'm a code-monkey that's increasingly taken on SysAdmin duties for my small company. My code is our product, and increasingly we provide the same app as SaaS. About 18 months ago I moved our servers from a premium hosting centric vendor to a barebones rack pusher in a tier IV data center. (Literally across the street.) This ment doing much more ourselves--things like networking, storage and monitoring. As part the big move, to replace our leased direct attached storage from the hosting company, I built a 9TB two-node NAS based on SuperMicro chassises, 3ware RAID cards, Ubuntu 10.04, two dozen SATA disks, DRBD and . It's all lovingly documented in three blog posts: Building up & testing a new 9TB SATA RAID10 NFSv4 NAS: Part I, Part II and Part III. We also setup a Cacit monitoring system. Recently we've been adding more and more data points, like SMART values. I could not have done all this without the awesome boffins at ServerFault. It's been a fun and educational experience. My boss is happy (we saved bucket loads of $$$), our customers are happy (storage costs are down), I'm happy (fun, fun, fun). Until yesterday. Outage & Recovery: Some time after lunch we started getting reports of sluggish performance from our application, an on-demand streaming media CMS. About the same time our Cacti monitoring system sent a blizzard of emails. One of the more telling alerts was a graph of iostat await. Performance became so degraded that Pingdom began sending "server down" notifications. The overall load was moderate, there was not traffic spike. After logging onto the application servers, NFS clients of the NAS, I confirmed that just about everything was experiencing highly intermittent and insanely long IO wait times. And once I hopped onto the primary NAS node itself, the same delays were evident when trying to navigate the problem array's file system. Time to fail over, that went well. Within 20 minuts everything was confirmed to be back up and running perfectly. Post-Mortem: After any and all system failures I perform a post-mortem to determine the cause of the failure. First thing I did was ssh back into the box and start reviewing logs. It was offline, completely. Time for a trip to the data center. Hardware reset, backup an and running. In /var/syslog I found this scary looking entry: Nov 15 06:49:44 umbilo smartd[2827]: Device: /dev/twa0 [3ware_disk_00], 6 Currently unreadable (pending) sectors Nov 15 06:49:44 umbilo smartd[2827]: Device: /dev/twa0 [3ware_disk_07], SMART Prefailure Attribute: 1 Raw_Read_Error_Rate changed from 171 to 170 Nov 15 06:49:45 umbilo smartd[2827]: Device: /dev/twa0 [3ware_disk_10], 16 Currently unreadable (pending) sectors Nov 15 06:49:45 umbilo smartd[2827]: Device: /dev/twa0 [3ware_disk_10], 4 Offline uncorrectable sectors Nov 15 06:49:45 umbilo smartd[2827]: Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error Nov 15 06:49:45 umbilo smartd[2827]: # 1 Short offline Completed: read failure 90% 6576 3421766910 Nov 15 06:49:45 umbilo smartd[2827]: # 2 Short offline Completed: read failure 90% 6087 3421766910 Nov 15 06:49:45 umbilo smartd[2827]: # 3 Short offline Completed: read failure 10% 5901 656821791 Nov 15 06:49:45 umbilo smartd[2827]: # 4 Short offline Completed: read failure 90% 5818 651637856 Nov 15 06:49:45 umbilo smartd[2827]: So I went to check the Cacti graphs for the disks in the array. Here we see that, yes, disk 7 is slipping away just like syslog says it is. But we also see that disk 8's SMART Read Erros are fluctuating. There are no messages about disk 8 in syslog. More interesting is that the fluctuating values for disk 8 directly correlate to the high IO wait times! My interpretation is that: Disk 8 is experiencing an odd hardware fault that results in intermittent long operation times. Somehow this fault condition on the disk is locking up the entire array Maybe there is a more accurate or correct description, but the net result has been that the one disk is impacting the performance of the whole array. The Question(s) How can a single disk in a hardware SATA RAID-10 array bring the entire array to a screeching halt? Am I being naïve to think that the RAID card should have dealt with this? How can I prevent a single misbehaving disk from impacting the entire array? Am I missing something?

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• Wesquare (NL) helps major CG customer integrating Oracle Service Cloud (RightNow) with JDEdwards

  - by Richard Lefebvre

  Normal 0 false false false EN-US X-NONE X-NONE When this well known, Italy based, CG player claimed that they needed a new CRM tool, Oracle partner WeSquare had a precise idea of what would be required, knowing that the customer was using JDEdwards as an ERP: they immediately thoughts about a solution that would help synchronizing the customer’s back-end system with the new CRM interface. The customer asked for presentations from three companies, including Oracle, and eventually selected Oracle Service Cloud (RightNow) with Alfa Sistemi (Oracle Platinum Partner) as a System Integrator supported by Wesquare (Oracle Gold partner specialized in RightNow). Synchronizing an On Premises ERP with a new SaaS based CRM platform could be seen as an uphill task, but WeSquare was determined, during the presales cycle, to prove that they had the skills and the attitude to make the difference. So, they rolled up their sleeves and got to it: five days of relentless work, missed lunches, and hours of brainstorming showed its result in the form of a new interface that works fabulously well with the JDEdwards ERP back-end and was successfully pitched by Oracle to the end-customer to win the deal! WeSquare took the occasion to learn that they can integrate Oracle Service Cloud (RightNow) with practically every other solution that a customer may run. As part of the project, WeSquare was also involved in different add-on’s development with the aim of enriching Oracle Service Cloud’s functionality. WeSquare is based in The Netherlands with an in-shore practice supported by off-shore teams in India. WeSquare can integrate and synchronize any application with RightNow. For more information, visit www.wesquare.nl or contact Wiebe Blankenberg (Managing Director) at +31 (0) 6 3632 1104 /* 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-qformat:yes; 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-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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• Do you know about the Visual Studio 2010 Database Projects Guidance?

  - by Martin Hinshelwood

  Early on in the Team System (now Visual Studio ALM) cycle a new product surfaced within Team System that was affectionately called “Data Dude”, but had the more formal name of “Visual Studio 2005 Team Edition for Database Professionals”. The purpose of this product was to try and make the database a “first class citizen” in the development world. Those that started using Visual Studio 2005 Team Edition for Database Professionals (Data Dude) loved it, but everyone else did not get it. The capabilities were a little patchy, but the one thing it did bring to the party was the ability to put your database schema under source control. This was revolutionary as previously your DBA sat as far away from the team as possible, and usually in a dark cupboard, now they could partake of all the goodness of Version Control, Work Item Tracking and automated builds. The problem was that the understanding required to manage these projects was very different to that needed previously. Then the Visual Studio ALM Rangers got a hold of it…and produced some of the best guidance available. Figure: Download the guidance from http://vsdatabaseguide.codeplex.com/ This guidance discusses scenarios and approaches of using the Database Projects in Visual Studio 2010 to help you use the tools more effectively and maximize their value to your organization This guidance is focused on these five areas: Solution and Project Management Source Code Control and Configuration Management Integrating External Changes with the Project System Build and Deployment Automation with Visual Studio Database Projects Database Testing and Deployment Verification Each of these areas has common guidance, usage scenarios, hands on labs, and lessons learned from real world engagements and the community discussions.   The guidance is broken down into three packages: Guidance documentation Hands-on-lab (HOL) documentation note: The documentation is available in XPS-only format packages or complete XPS,PDF,DOCX format packages HOL Package If you need assistance and no one else can help, then you may need to call the Visual Studio ALM Rangers. The Visual Studio ALM Rangers have the mission to provide out of band solutions for missing features or guidance. They are supported by Microsoft Product Group, Microsoft Consulting Services, Microsoft Most Valued Professionals (MVPs) and technical specialists from technology communities around the globe, giving you a real-world view from the field, where the technology has been tested and used. For more information on the Rangers please visit http://msdn.microsoft.com/en-us/vstudio/ee358786.aspx and for more a list of other Rangers projects please see http://msdn.microsoft.com/en-us/vstudio/ee358787.aspx.

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• Data Model Dissonance

  - by Tony Davis

  So often at the start of the development of database applications, there is a premature rush to the keyboard. Unless, before we get there, we’ve mapped out and agreed the three data models, the Conceptual, the Logical and the Physical, then the inevitable refactoring will dog development work. It pays to get the data models sorted out up-front, however ‘agile’ you profess to be. The hardest model to get right, the most misunderstood, and the one most neglected by the various modeling tools, is the conceptual data model, and yet it is critical to all that follows. The conceptual model distils what the business understands about itself, and the way it operates. It represents the business rules that govern the required data, its constraints and its properties. The conceptual model uses the terminology of the business and defines the most important entities and their inter-relationships. Don’t assume that the organization’s understanding of these business rules is consistent or accurate. Too often, one department has a subtly different understanding of what an entity means and what it stores, from another. If our conceptual data model fails to resolve such inconsistencies, it will reduce data quality. If we don’t collect and measure the raw data in a consistent way across the whole business, how can we hope to perform meaningful aggregation? The conceptual data model has more to do with business than technology, and as such, developers often regard it as a worthy but rather arcane ceremony like saluting the flag or only eating fish on Friday. However, the consequences of getting it wrong have a direct and painful impact on many aspects of the project. If you adopt a silo-based (a.k.a. Domain driven) approach to development), you are still likely to suffer by starting with an incomplete knowledge of the domain. Even when you have surmounted these problems so that the data entities accurately reflect the business domain that the application represents, there are likely to be dire consequences from abandoning the goal of a shared, enterprise-wide understanding of the business. In reading this, you may recall experiences of the consequence of getting the conceptual data model wrong. I believe that Phil Factor, for example, witnessed the abandonment of a multi-million dollar banking project due to an inadequate conceptual analysis of how the bank defined a ‘customer’. We’d love to hear of any examples you know of development projects poleaxed by errors in the conceptual data model. Cheers, Tony

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• What algorithms can I use to detect if articles or posts are duplicates?

  - by michael

  I'm trying to detect if an article or forum post is a duplicate entry within the database. I've given this some thought, coming to the conclusion that someone who duplicate content will do so using one of the three (in descending difficult to detect): simple copy paste the whole text copy and paste parts of text merging it with their own copy an article from an external site and masquerade as their own Prepping Text For Analysis Basically any anomalies; the goal is to make the text as "pure" as possible. For more accurate results, the text is "standardized" by: Stripping duplicate white spaces and trimming leading and trailing. Newlines are standardized to \n. HTML tags are removed. Using a RegEx called Daring Fireball URLs are stripped. I use BB code in my application so that goes to. (ä)ccented and foreign (besides Enlgish) are converted to their non foreign form. I store information about each article in (1) statistics table and in (2) keywords table. (1) Statistics Table The following statistics are stored about the textual content (much like this post) text length letter count word count sentence count average words per sentence automated readability index gunning fog score For European languages Coleman-Liau and Automated Readability Index should be used as they do not use syllable counting, so should produce a reasonably accurate score. (2) Keywords Table The keywords are generated by excluding a huge list of stop words (common words), e.g., 'the', 'a', 'of', 'to', etc, etc. Sample Data text_length, 3963 letter_count, 3052 word_count, 684 sentence_count, 33 word_per_sentence, 21 gunning_fog, 11.5 auto_read_index, 9.9 keyword 1, killed keyword 2, officers keyword 3, police It should be noted that once an article gets updated all of the above statistics are regenerated and could be completely different values. How could I use the above information to detect if an article that's being published for the first time, is already existing within the database? I'm aware anything I'll design will not be perfect, the biggest risk being (1) Content that is not a duplicate will be flagged as duplicate (2) The system allows the duplicate content through. So the algorithm should generate a risk assessment number from 0 being no duplicate risk 5 being possible duplicate and 10 being duplicate. Anything above 5 then there's a good possibility that the content is duplicate. In this case the content could be flagged and linked to the article's that are possible duplicates and a human could decide whether to delete or allow. As I said before I'm storing keywords for the whole article, however I wonder if I could do the same on paragraph basis; this would also mean further separating my data in the DB but it would also make it easier for detecting (2) in my initial post. I'm thinking weighted average between the statistics, but in what order and what would be the consequences...

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• Fixing a NoClassDefFoundError

  - by Chris Okyen

  I have some code: package ftc; import java.util.Scanner; public class Fer_To_Cel { public static void main(String[] argv) { // Scanner object to get the temp in degrees Farenheit Scanner keyboard = new Scanner(System.in); boolean isInt = true; // temporarily put as true in case the user enters a valid int the first time int degreesF = 0; // initialy set to 0 do { try { // Input the temperature text. System.out.print("\nPlease enter a temperature (integer number, no fractional part) in degrees Farenheit: "); degreesF = Integer.parseInt(keyboard.next()); // Get user input and Assign the far. temperature variable, which is casted from String to int. } // Let the user know in a user friendly notice that the value entered wasnt an int ( give int value range ) , and then give error log catch(java.lang.Exception e) { System.out.println("Sorry but you entered a non-int value ( needs to be between ( including ) -2,147,483,648 and 2,147,483,647 ).. \n"); e.printStackTrace(); isInt = false; } } while(!isInt); System.out.println(""); // print a new line. final int degreesC = (5*(degreesF-32)/9); // convert the degrees from F to C and store the resulting expression in degreesC // Print out a newline, then print what X degrees F is in Celcius. System.out.println("\n" + degreesF + " degrees Farenheit is " + degreesC + " degrees Celcius"); } } And The following error: C:\Program Files\Java\jdk1.7.0_06\bin>java Fer_To_Cel Exception in thread "main" java.lang.NoClassDefFoundError: Fer_To_Cel (wrong name: ftc/Fer_To_Cel) at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:791) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14 at java.net.URLClassLoader.defineClass(URLClassLoader.java:449) at java.net.URLClassLoader.access$100(URLClassLoader.java:71) at java.net.URLClassLoader$1.run(URLClassLoader.java:361) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:423) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:356) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:480) The code compiled without compile errors, but presented errors during execution. Which leads me to two questions. I know Errors can be termed Compiler, Runtime and Logic Errors, but the NoClassDefFoundError inherits java.lang.LinkageError. Does that make it a Linker error, being niether of the three types of errors I listed, If I am right this is the answer. For someone else who obtains the singular .java file and compiles it, would this be the only way to solve this problem? Or can I (should I ) do/have done something to fix this problem? Basically, based on a basis of programming, is this a fault of me as the writer? Could this be done once on, my half and be distributed and not needed be done again?

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• Memory read/write access efficiency

  - by wolfPack88

  I've heard conflicting information from different sources, and I'm not really sure which one to believe. As such, I'll post what I understand and ask for corrections. Let's say I want to use a 2D matrix. There are three ways that I can do this (at least that I know of). 1: int i; char **matrix; matrix = malloc(50 * sizeof(char *)); for(i = 0; i < 50; i++) matrix[i] = malloc(50); 2: int i; int rowSize = 50; int pointerSize = 50 * sizeof(char *); int dataSize = 50 * 50; char **matrix; matrix = malloc(dataSize + pointerSize); char *pData = matrix + pointerSize - rowSize; for(i = 0; i < 50; i++) { pData += rowSize; matrix[i] = pData; } 3: //instead of accessing matrix[i][j] here, we would access matrix[i * 50 + j] char *matrix = malloc(50 * 50); In terms of memory usage, my understanding is that 3 is the most efficient, 2 is next, and 1 is least efficient, for the reasons below: 3: There is only one pointer and one allocation, and therefore, minimal overhead. 2: Once again, there is only one allocation, but there are now 51 pointers. This means there is 50 * sizeof(char *) more overhead. 1: There are 51 allocations and 51 pointers, causing the most overhead of all options. In terms of performance, once again my understanding is that 3 is the most efficient, 2 is next, and 1 is least efficient. Reasons being: 3: Only one memory access is needed. We will have to do a multiplication and an addition as opposed to two additions (as in the case of a pointer to a pointer), but memory access is slow enough that this doesn't matter. 2: We need two memory accesses; once to get a char *, and then to the appropriate char. Only two additions are performed here (once to get to the correct char * pointer from the original memory location, and once to get to the correct char variable from wherever the char * points to), so multiplication (which is slower than addition) is not required. However, on modern CPUs, multiplication is faster than memory access, so this point is moot. 1: Same issues as 2, but now the memory isn't contiguous. This causes cache misses and extra page table lookups, making it the least efficient of the lot. First and foremost: Is this correct? Second: Is there an option 4 that I am missing that would be even more efficient?

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• To make or not to make...python-nautilus a dependency?

  - by George Edison

  That is the question! Okay, all silliness aside, I really am forced to make a difficult decision here. My application is written in C++ and allows other scripts to invoke methods via XML-RPC. One of these scripts is a Nautilus extension written in Python. The extension is packaged with the rest of the application and copied to the appropriate place when installed (/usr/share/nautilus-python/extensions). Now the problem is that the Nautilus extension requires the python-nautilus package to be installed to be operational. So therefore I have three options: Make the python-nautilus package a dependency. This option will ensure that anyone who installs my package will be able to use the Nautilus extension. However, this option will not be attractive to XFCE or KDE users - a ton of python-nautilus's dependencies will be installed on their machines and take up a lot of space - even if they never use Nautilus. Put the python-nautilus package in the suggests: or recommends: field. This option provides the end-user with a way to avoid installing the python-nautilus package (by providing the --no-install-suggests or --no-install-recommends argument to apt-get). However, this won't work when the user installs the package in the Software Center. (I always get mixed up as to which of those two fields are installed by default.) Prompt the user when the application is installed or first launched. This option is more complicated than the others but offers the best compromise between making it easy for the user to install python-nautilus (without going into a technical explanation) and not installing it when the user doesn't need it (or want it). I guess the best way to implement this is a simple prompt that invokes apt-get if the user would like the package installed. Don't install the package at all. This option ensures that nobody has python-nautilus installed on their machine unless they want it. However, this also means that my Nautilus extension will simply not run on the end-user's machine unless they manually install the package. Which of these options seems the best choice? Have I missed any pros and cons for each of the options?

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• JSR 355 Final Release, and moves JCP to version 2.9

  - by heathervc

  JSR 355, JCP EC Merge, passed the JCP EC Final Approval Ballot on 13 August 2012, with 14 Yes votes, 1 abstain (1 member did not vote) on the SE/EE EC, and 12 yes votes (2 members were not eligible to vote) on the ME EC.  JSR 355 posted a Final Release this week, moving the JCP program version to JCP 2.9.  The transition to a merged EC will happen after the 2012 EC Elections, as defined in the Appendix B of the JCP (pasted below), and the EC will operate under the new EC Standing Rules. In the previous version (2.8) of this Process Document there were two separate Executive Committees, one for Java ME and one for Java SE and Java EE combined. The single Executive Committee described in this version of the Process Document will be implemented through the following process: The 2012 annual elections will be held as defined in JCP 2.8, but candidates will be informed that if they are elected their term will be for only a single year, since all candidates must stand for re-election in 2013. Immediately after the 2012 election the two ECs will be merged. Oracle and IBM's second seats will be eliminated, resulting in a single EC with 30 members. All subsequent JSR ballots (even for in-progress JSRs) will then be voted on by the merged EC. For the 2013 annual elections three Ratified and two Elected Seats will be eliminated, thereby reducing the EC to 25 members. All 25 seats will be up for re-election in 2013. Members elected in 2013 will be ranked to determine whether their initial term will be one or two years. The 50% of Ratified and 50% of Elected members who receive the most votes will serve an initial two-year term, while all others will serve an initial one year term. All members elected in 2014 and subsequently will serve a two-year term. For clarity, note that the provisions specified in this version of the Process Document regarding a merged EC will apply to subsequent ballots on all existing JSRs, whether or not the Spec Leads of those JSRs chose to adopt this version of the Process Document in its entirety. <end of Appendix> Also of note:  the materials and minutes from the July EC meeting and the June EC Meeting are now available--following the July EC Meeting, Samsung and SK Telecom lost their EC seats. The June EC meeting also had a public portion--the audio from the public portion of the EC meeting are now posted online.  For Spec Leads there is also the recording of the EG Nominations call.

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• EBS Accounts Payables Customer Advisory

  - by cwarticki

  Blogging to let you know of an important set of Oracle Payables patches that were released for R12.1 customers.  Accounts Payable Customer Advisory: Dear Valued Oracle Support Customer, Since the release of R12.1.3 a number of recommended Payables patches have been made available as standalone patches, to help address important business process incidents. Adoption of these patches is highly recommended. To further facilitate adoption of these Payables patches Oracle has consolidated them into a single Recommended Patch Collection (RPC). The RPC is a collection of recommended Payables patches created with the following goals in mind: Stability: Help address issues that are identified by Oracle Development and Oracle Software Support that may interfere with the normal completion of important business processes such as period close. Root Cause Fixes: Help make available root cause fix for data integrity that may delay period close, normal invoice flow and other business actions. Compact: Keep the file footprint as small as possible to help facilitate the install process and minimize testing. Granular: Collection of patches based on functional area that allows customer to apply, based on their individual needs and goals, all three RPC’s at once or in phases. Payables: -          New AP RPC (14273383:R12.AP.B) has all data corruption root cause fixes known to date plus tons of other crucial fixes (Note: 1397581.1). -          Companion must have RPCs: o   Note: 1481221.1: R12.1: Payments Recommended Patch Collection (IBY RPC), August 2012 o   Note: 1481235.1: R12.1: E-Business Tax Recommended Patch Collection (ZX RPC), August 2012 o   Note: 1481222.1: R12.1: Sub Ledger Accounting (SLA) Recommended Patch Collection (XLA RPC), August 2012 -          This time we beat the system far harder on testing and it held up remarkably well. We could not get any data corruption events in the Invoice Cancel/Discard flow (that is the #1 generator) neither we could cause Orphan Events in the system. Therefore this is very good code. Financials: -          ALL FIN modules now have RPCs: full listing is in (Note: 954704.1)

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• How to troubleshoot ethernet port on laptop

  - by Psallas Vassilios

  I have a problem with my wired connection. To be more specific, my laptop doesn't seems to recognize that I have plugged in an ethernet cable. I tried to download new drivers for my ethernet card, but I couldn't find any solutions. Maybe because I am new to Linux, so I'm not familiar with running commands in the terminal. OK I have typed the command and here are the results: 00:04.0 Ethernet controller [0200]: Silicon Integrated Systems [SiS] 191 Gigabit Ethernet Adapter [1039:0191] (rev 02) For the second reply I don't know if the following is what you asked me: ?Memory: 3.9 GiB ?Processor: Intel Core 2 Duo CPU P8800 @ 2.66GHz × 2 ?OS type: 32-bit My Ethernet connection had some problem on Windows too. I have changed recently my internet provider, and since then my ethernet cable is not recognized by the laptop. At that time I was still on Windows. I thought that with Ubuntu the problem would be solved, but unfortunately the problem still persists. If someone can help me to solve my problem I'll be thankful. Here are the results of the three first commands you told me to run: lsmod | grep sis190 sis190 22570 0 sudo modprobe sis190 ifconfig eth0 Link encap:Ethernet HWaddr 00:90:f5:90:81:7e UP BROADCAST MULTICAST MTU:1500 Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:0 (0.0 B) TX bytes:0 (0.0 B) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:185 errors:0 dropped:0 overruns:0 frame:0 TX packets:185 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:22672 (22.6 KB) TX bytes:22672 (22.6 KB) wlan0 Link encap:Ethernet HWaddr 00:25:d3:2c:3a:ae inet addr:192.168.1.72 Bcast:192.168.1.255 Mask:255.255.255.0 inet6 addr: fe80::225:d3ff:fe2c:3aae/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:260 errors:0 dropped:0 overruns:0 frame:0 TX packets:363 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:71992 (71.9 KB) TX bytes:52000 (52.0 KB) and the results of running the last two commands: dmesg | grep -e eth -e sis190 [ 0.816667] sis190: sis190 Gigabit Ethernet driver 1.4 loaded [ 0.816728] sis190 0000:00:04.0: setting latency timer to 64 [ 0.816751] sis190: 0000:00:04.0: Read MAC address from EEPROM [ 0.904032] sis190: 0000:00:04.0: Realtek PHY RTL8201 transceiver at address [ 1.416030] sis190: 0000:00:04.0: Using transceiver at address 1 as default [ 1.448235] sis190 0000:00:04.0: eth0: 0000:00:04.0: SiS 191 PCI Gigabit Ethernet adapter at f8410000 (IRQ: 19), 00:90:f5:90:81:7e [ 1.448238] sis190 0000:00:04.0: eth0: GMII mode. [ 1.448243] sis190 0000:00:04.0: eth0: Enabling Auto-negotiation [ 11.560907] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 16.372019] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 16.372265] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready [ 26.424038] sis190 0000:00:04.0: eth0: auto-negotiating... nm-tool NetworkManager Tool State: connected (global) - Device: eth0 ----------------------------------------------------------------- Type: Wired Driver: sis190 State: unavailable Default: no HW Address: 00:90:F5:90:81:7E Capabilities: Carrier Detect: yes Wired Properties Carrier: off

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• Interesting Topics in Comp. Sci. for New Students?

  - by SoulBeaver

  I hope this is the right forum to ask this question. Last friday I was in a discussion with my professors about the students' lack of motivation and interest in the field of Computer Science. All of the students are enrolled, but through questionnaires and other questions that my professor posed it was revealed that over 90% of all enrolled students are just in it for the reward of getting a job sometime in the future (since it's a growing field with high job potential) I asked my professor for the permission to take over the first couple of lectures and try and motivate, interest and inspire students for the field of Computer Science and programming in particular (this is the Intro to Programming course). This request was granted and I now have a week to come up with a lecture topic for my professor's five groups. My main goal isn't to teach, I just want to get students to be as interested in the field as I am. I want to show them what's possible, what awesome magical things have been done in the field, the future we are heading towards using programming and Comp. Sci. Therefore, I would like to pose this question: I have a few topics, materials and sample projects that I would like to talk about: -- Grace Hopper (It is my hope to interest the female programmers in the class. There are never more than two or three per group and they, more than males, are prone to jumping ship and abandoning Comp. Sci.) -- The Singularity Institute -- Alan Turing -- Robotics -- Programming not as a chore or a must, but the idea that we are, at our core, the nexus to which anything anybody does in the digital world is connected to. We are the problem solvers; we assemble all the parts together and we are the ones that, essentially, make the vision a reality. -- Give them an idea for a programming project which, through the help of the professor, could be significant to every student (I want students to not only feel interested in the topic, but they should feel important, that what they do here makes a difference) Do you have interesting topics worthy of discussion, something I can tell the students which they can get interested about? How would you approach the lecture? If you had 90 minutes worth of time to try and get students interested in the project, what would you do?

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• Wrapping REST based Web Service

  - by PaulPerry

  I am designing a system that will be running online under Microsoft Windows Azure. One component is a REST based web service which will really be a wrapper (using proxy pattern) which calls the REST web services of a business partner, which has to do with BLOB storage (note: we are not using azure storage). The majority of the functionality will be taking a request, calling our partner web service, receiving the request and then passing that back to the client. There are a number of reasons for doing this, but one of the big ones is that we are going to support three clients: our desktop application (win and mac), mobile apps (iOS), and a web front end. Having a single API which we then send to our partner protects us if that partner ever changes. I want our service to support both JSON and XML for the data transfer format, JSON for web and probably XML for the desktop and mobile (we already have an XML parser in those products). Our partner also supports both of these formats. I was planning on using ASP.NET MVC 4 with the Web API. As I design this, the thing that concerns me is the static type checking of C#. What if the partner adds or removes elements from the data? We can probably defensively code for that, but I still feel some concern. Also, we have to do a fair amount of tedious coding, to setup our API and then to turn around and call our partner’s API. There probably is not much choice on it though. But, in the back of my mind I wonder if maybe a more dynamic language would be a better choice. I want to reach out and see if anybody has had to do this before, what technology solutions they have used to (I am not attached to this one, these days Azure can host other technologies), and if anybody who has done something like this can point out any issues that came up. Thanks! Researching the issue seems to only find solutions which focus on connecting a SOAP web service over a proxy server, and not what I am referring to here. Note: Cross posted (by suggestion) from http://stackoverflow.com/questions/11906802/wrapping-rest-based-web-service Thank you!

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• Can working exclusively with niche apps or tech hurt your career in software development? How to get out of the cycle? [closed]

  - by Keoma

  I'm finding myself in a bit of a pickle. I've been at a pretty comfortable IT group for almost a decade. I got my start here working on web development, mostly CRUD, but have demonstrated the ability to figure out more complex problems. I'm not a rock star, but I have received many compliments on my programming aptitude, and technologists and architects have commented on my ability to pick things up (for example, I recently learned a very popular web framework that shall remain nameless since I don’t want to be identified). My problem is that, over time, my responsibilities have been shifting towards work such as support or ‘development’ with some rather niche products (afraid to mention here due to potential for being identified). Some of this work, if it includes anything resembling coding, is very menial scripting in languages such as Powershell or VBScript. The vast majority of the time, however, a typical day consists of going back and forth with the product’s vendor support to send them logs and apply configuration changes or patches they recommend. I’m basically starved for some actual software development. However, even though I’m more than capable of doing that development work (and actually do a much better job at it than anything else), our boss is more interested in the kind of work I mentioned above, her reasoning being that since no one else in the organization wants to do it, it must mean job security. This has been going on for close to 3 years, and the only reason I have held on is on the promise that we would eventually get more development projects assigned to us. Well, that turned out not to be true at all. A recent talk with the boss has just made it more explicitly clear, as she told me in no uncertain terms that it’s very likely that development work (web or otherwise) would go to another group. The reason given to me is that our we don’t have enough resources in our group to handle that. So now I find myself in the position that I either have to stay in what has essentially become a dead end IT job that is tied to the fortunes of a niche stack of apps, or try to find a position that will be better for my long term career. My problem (is it a problem?), however, is that compared to others, my development projects in the last three years are very sparse in number. To compound things, projects using the latest and most popular frameworks, amount to the big fat number of just one—with no work of that kind in the foreseeable future. I am very concerned that this sparseness in my resume is a deficit, and that it will hurt my chances of landing a different job. I’m also wondering how much it will hurt me, and whether that can be ameliorated with hobby projects of my own. I guess I’m looking for opinions. Thank you very much for reading.

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• Small script to look for Project Replication actions that have failed

  - by Trond Strømme

  Today when looking at a couple of projects on a ZFS 7320 Storage Appliance I noticed on one project that one of its replication actions had failed, as I hadn't checked the Recent Alerts log yet I was not aware of this. I decided to write a small script to check if there were others that had failed. Nothing fancy, just a loop through all projects, look at the project's replication child and compare the values of the last_sync and last_try properties and print the result if they're not equal. (There are probably more sensible ways of doing this, but at least it involves me getting the chance to put on my headphones and doing just a little bit of coding.) script // this script will locate failed project level replication // it will look at the sync times for 'last_sync' and 'last_try' // and compare these, if they deviate you should investigate. // NOTE! this code is offered 'as is' Run at your own risk, // it will probably work as intended, but in now way can I // (or Oracle) be held responsible if your server starts behaving // like a three year old kid in a candy store.. (not that mine do, // they are very well behaved boys...) run('configuration'); run('storage'); printf('Host: %s, pool: %s\n', get('owner'),get('pool')); run('cd /'); run('shares'); proj=list(); printf("total projects: %d\n",proj.length +'\n'); // just for project level replication for(i=0;i<proj.length;i++){ run('select '+proj[i]); run('replication'); //get all replication actions preps = list(); for(j=0;j<preps.length;j++){ run('select ' + preps[j]); last_sync = get('last_sync'); last_try = get('last_try'); // printf("target %s\n", get('target')); //why the flip does this not get the proper name? if(!( last_sync.valueOf() === last_try.valueOf())){ printf("sync has failed for %s %s\n", proj[i], get('target')); }else{ // printf("OK %s %s\n", proj[i], get('target')); } run('done'); //done with the replica action } run('done'); run('done'); } printf("finished\n"); For a more on how to run the script, or testing it please look at my previous post. Sample output: Host: elb1sn01, pool: exalogic total projects: 45 sync has failed for ACSExalogicSystem cb3a24fe-ad60-c90f-d15d-adaafd595639 finished

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• prism and multiple screens

  - by Avi

  OK - I am studying Prism a little because of a "free weekend" offer on Pluralsight. As this is proving too complex for me, I went to the Prism book and looked at the forward, and this is what it said: What comes after “Hello, World?” WPF and Silverlight developers are blessed with an abundance of excellent books... There’s no lack of tutorials on Model-View-ViewModel ... But they stop short of the guidance you need to deliver a non-trivial application in full. Your first screen goes well. You add a second screen and a third. Because you started your solution with the built-in “Navigation Application Template,” adding new screens feels like hanging shirts on a closet rod. You are on a roll. Until the harsh reality of real application requirements sets in. As it happens, your application has 30 screens not three. There’s no room on that closet rod for 30 screens. Some screens are modal pop-ups; you don’t navigate to a pop-up. Screens become interdependent such that user activity in one screen triggers changes that propagate throughout the UI. Some screens are optional; others are visible only to authorized users. Some screens are permanent, while other screens can be opened and closed at will. You discover that navigating back to a previously displayed screen creates a new instance. That’s not what you expected and, to your horror, the prior instance is gone along with the user’s unsaved changes. Now the issue is, I don't relate to this description. I've never been a UI programmer, but same as everyone else I'm using Windows apps such as MS-Office, and web sites such as Amazon, Facebook and StackExchange. And I look at these and I don't see many "so many screens" issues! Indeed, the only applications having many windows I can think of is Visual Studio. Maybe also Visio, a little. But take Word - You have a ribbon and a main window. Or take Facebook: You have those lists on the left (Favorites, Lists, Groups etc.), the status middle, the adds and then the Contacts sidebar. But it's only one page. Of course, I understand that in enterprise scenarios there are dashboad applications where multiple segments of the screen are updated from multiple non-related services. This I dig. But other scenarios? So - What am I missing? What is the "multiple screens" monster Pirsm is supposed to be the silver bullet solution for? Shoud I invest in studying Prism in addition to learning WPF or ASP.NET MVC?

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• C# OpenGL problem with animation

  - by user3696303

  there is a program that simulates a small satellite and requires that a rotation animation of the satellite along the three axes. But when you try to write an animation problem during compilation: the program simply closes (shutdown occurs when swapbuffers, mainloop, redisplay), when you write the easiest programs have the same problem arose. Trying to catch exception by try-catch but here is not exception. How to solve this? I suffer with this a few days. Work in c# visual studio 2008 framework namespace WindowsFormsApplication6 { public partial class Form1 : Form { public Form1() { try { InitializeComponent(); AnT1.InitializeContexts(); } catch(Exception) { Glut.glutDisplayFunc(Draw); Glut.glutTimerFunc(50, Timer, 0); Glut.glutMainLoop(); } } void Timer(int Unused) { Glut.glutPostRedisplay(); Glut.glutTimerFunc(50, Timer, 0); } private void AnT1_Load(object sender, EventArgs e) { Glut.glutInit(); Glut.glutInitDisplayMode(Glut.GLUT_RGB | Glut.GLUT_DOUBLE | Glut.GLUT_DEPTH); Gl.glClearColor(255, 255, 255, 1); Gl.glViewport(0, 0, AnT1.Width, AnT1.Height); Gl.glMatrixMode(Gl.GL_PROJECTION); Gl.glLoadIdentity(); Glu.gluPerspective(45, (float)AnT1.Width / (float)AnT1.Height, 0.1, 200); Gl.glMatrixMode(Gl.GL_MODELVIEW); Gl.glLoadIdentity(); Gl.glEnable(Gl.GL_DEPTH_TEST); Gl.glClear(Gl.GL_COLOR_BUFFER_BIT | Gl.GL_DEPTH_BUFFER_BIT); Gl.glPushMatrix(); double xy = 0.2; Gl.glTranslated(xy, 0, 0); xy += 0.2; Draw(); Glut.glutSwapBuffers(); Glut.glutPostRedisplay(); Gl.glPushMatrix(); Draw(); Gl.glPopMatrix(); } void Draw() { Gl.glLoadIdentity(); Gl.glColor3f(0.502f, 0.502f, 0.502f); Gl.glTranslated(-1, 0, -6); Gl.glRotated(95, 1, 0, 0); Glut.glutSolidCylinder(0.7, 2, 60, 60); Gl.glLoadIdentity(); Gl.glColor3f(0, 0, 0); Gl.glTranslated(-1, 0, -6); Gl.glRotated(95, 1, 0, 0); Glut.glutWireCylinder(0.7, 2, 20, 20); } } }

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• Delay command execution over sockets

  - by David

  I've been trying to fix the game loop in a real time (tick delay) MUD. I realized using Thread.Sleep would seem clunky when the user spammed commands through their choice of client (Zmud, etc) e.g. east;south;southwest would wait three move ticks and then output everything from the past couple rooms. The game loop basically calls a Flush and Fill method for each socket during each tick (50ms) private void DoLoop() { Stopwatch stopWatch = new Stopwatch(); stopWatch.Start(); while (running) { // for each socket, flush and fill ConnectionMonitor.Update(); stopWatch.Stop(); WaitIfNeeded(stopWatch.ElapsedMilliseconds); stopWatch.Reset(); } } The Fill method fires the command events, but as mentioned before, they currently block using Thread.Sleep. I tried adding a "ready" flag to the state object that attempts to execute the command along with a queue of spammed commands, but it ends up executing one command and queuing up the rest i.e. each subsequent command executes something that got queued up that should've been executed before. I must be missing something about the timer. private readonly Queue<SpammedCommand> queuedCommands = new Queue<SpammedCommand>(); private bool ready = true; private void TryExecuteCommand(string input) { var commandContext = CommandContext.Create(input); var player = Server.Current.Database.Get<Player>(Session.Player.Key); var commandInfo = Server.Current.CommandLookup .FindCommand(commandContext.CommandName, player.IsAdmin); if (commandInfo != null) { if (!ready) { // queue command queuedCommands.Enqueue(new SpammedCommand() { Context = commandContext, Info = commandInfo }); return; } if (queuedCommands.Count > 0) { // queue the incoming command queuedCommands.Enqueue(new SpammedCommand() { Context = commandContext, Info = commandInfo, }); // dequeue and execute var command = queuedCommands.Dequeue(); command.Info.Command.Execute(Session, command.Context); setTimeout(command.Info.TickLength); return; } commandInfo.Command.Execute(Session, commandContext); setTimeout(commandInfo.TickLength); } else { Session.WriteLine("Command not recognized"); } } Finally, setTimeout was supposed to set the execution delay (TickLength) for that command, and makeReady just sets the ready flag on the state object to true. private void setTimeout(TickDelay tickDelay) { ready = false; var t = new System.Timers.Timer() { Interval = (long) tickDelay, AutoReset = false, }; t.Elapsed += makeReady; t.Start(); // fire this in tickDelay ms } // MAKE READYYYYY!!!! private void makeReady(object sender, System.Timers.ElapsedEventArgs e) { ready = true; } Am I missing something about the System.Timers.Timer created in setTimeout? How can I execute (and output) spammed commands per TickLength without using Thread.Sleep?

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• Write and fprintf for file I/O

  - by Darryl Gove

  fprintf() does buffered I/O, where as write() does unbuffered I/O. So once the write() completes, the data is in the file, whereas, for fprintf() it may take a while for the file to get updated to reflect the output. This results in a significant performance difference - the write works at disk speed. The following is a program to test this: #include <fcntl.h #include <unistd.h #include <stdio.h #include <stdlib.h #include <errno.h #include <stdio.h #include <sys/time.h #include <sys/types.h #include <sys/stat.h static double s_time; void starttime() { s_time=1.0*gethrtime(); } void endtime(long its) { double e_time=1.0*gethrtime(); printf("Time per iteration %5.2f MB/s\n", (1.0*its)/(e_time-s_time*1.0)*1000); s_time=1.0*gethrtime(); } #define SIZE 10*1024*1024 void test_write() { starttime(); int file = open("./test.dat",O_WRONLY|O_CREAT,S_IWGRP|S_IWOTH|S_IWUSR); for (int i=0; i<SIZE; i++) { write(file,"a",1); } close(file); endtime(SIZE); } void test_fprintf() { starttime(); FILE* file = fopen("./test.dat","w"); for (int i=0; i<SIZE; i++) { fprintf(file,"a"); } fclose(file); endtime(SIZE); } void test_flush() { starttime(); FILE* file = fopen("./test.dat","w"); for (int i=0; i<SIZE; i++) { fprintf(file,"a"); fflush(file); } fclose(file); endtime(SIZE); } int main() { test_write(); test_fprintf(); test_flush(); } Compiling and running I get 0.2MB/s for write() and 6MB/s for fprintf(). A large difference. There's three tests in this example, the third test uses fprintf() and fflush(). This is equivalent to write() both in performance and in functionality. Which leads to the suggestion that fprintf() (and other buffering I/O functions) are the fastest way of writing to files, and that fflush() should be used to enforce synchronisation of the file contents.

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