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  • How to dissuade a customer who just learned a technology and wants to use it everywhere?

    - by MainMa
    My customer recently discovered what is URL Rewriting, without completely understanding what it is, how it works and the pros and cons of it. Now, he asks for lots of strange changes in actual requirements of current projects and changes in old projects in order to implement what he believes is URL Rewriting. On one hand, I'm annoyed being asked to do things which doesn't make any sense instead of doing real work. On the other hand, I can't tell my customer that he doesn't understand anything in the subject despite his interest in it. I think many people have had situations when their manager or their customer just learned a new buzzword or a new technology, and he loved it so much than he wanted to use it in every project, everywhere, rewrite the whole codebase just to use this new thing, etc. Also, I've recently read something related on Programmers.SE where people told about their experiences when there was a huge buzz around XML, and some managers would ask to introduce XML in every project just to show to everyone that they have used it. So those who have been in similar situation, how have you managed it?

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  • Detecting collision between ball (circle) and brick(rectangle)?

    - by James Harrison
    Ok so this is for a small uni project. My lecturer provided me with a framework for a simple brickbreaker game. I am currently trying to overcome to problem of detecting a collision between the two game objects. One object is always the ball and the other objects can either be the bricks or the bat. public Collision hitBy( GameObject obj ) { //obj is the bat or the bricks //the current object is the ball // if ball hits top of object if(topX + width >= obj.topX && topX <= obj.topX + obj.width && topY + height >= obj.topY - 2 && topY + height <= obj.topY){ return Collision.HITY; } //if ball hits left hand side else if(topY + height >= obj.topY && topY <= obj.topY + obj.height && topX + width >= obj.topX -2 && topX + width <= obj.topX){ return Collision.HITX; } else return Collision.NO_HIT; } So far I have a method that is used to detect this collision. The the current obj is a ball and the obj passed into the method is the the bricks. At the moment I have only added statement to check for left and top collisions but do not want to continue as I have a few problems. The ball reacts perfectly if it hits the top of the bricks or bat but when it hits the ball often does not change directing. It seems that it is happening toward the top of the left hand edge but I cannot figure out why. I would like to know if there is another way of approaching this or if people know where I'm going wrong. Lastly the collision.HITX calls another method later on the changes the x direction likewise with y.

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  • HLSL How to flip geometry horizontally

    - by cubrman
    I want to flip my asymmetric 3d model horizontally in the vertex shader alongside an arbitrary plane parallel to the YZ plane. This should switch everything for the model from the left hand side to the right hand side (like flipping it in Photoshop). Doing it in pixel shader would be a huge computational cost (extra RT, more fullscreen samples...), so it must be done in the vertex shader. Once more: this is NOT reflection, i need to flip THE WHOLE MODEL. I thought I could simply do the following: Turn off culling. Run the following code in the vertex shader: input.Position = mul(input.Position, World); // World[3][0] holds x value of the model's pivot in the World. if (input.Position.x <= World[3][0]) input.Position.x += World[3][0] - input.Position.x; else input.Position.x -= input.Position.x - World[3][0]; ... The model is never drawn. Where am I wrong? I presume that messes up the index buffer. Can something be done about it? P.S. it's INSANELY HARD to format code here. Thanks to Panda I found my problem. SOLUTION: // Do thins before anything else in the vertex shader. Position.x *= -1; // To invert alongside the object's YZ plane.

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  • How to Print From Metro Apps in Windows 8

    - by Taylor Gibb
    Printing has become an application aware feature in Metro applications. This makes the outcome of a print job different from application to application, but the question remains, how do you print? Using the Keyboard Not all apps support printing in Windows 8, a good example of one that does is Mail. So fire up the default Mail app select an email you want to print. When you are ready, go ahead and press the ctrl + P keyboard combination. This will bring up a list of available print devices on the right-hand side, you can use the up and down arrows to select a printer. You will get most of the options you are use to when printing, so once you have set up your preferences go ahead and hit the print button. Using the Mouse If you would rather use your mouse, move it to the bottom right hand corner of your screen, which will bring up the Charms bar, from here you will need to click on the devices charm. Using this will list your printers as well as other devices, so make sure you select a printer. That’s all there is to it. How To Switch Webmail Providers Without Losing All Your Email How To Force Windows Applications to Use a Specific CPU HTG Explains: Is UPnP a Security Risk?

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  • EMEA OTN Virtual Technology Summit - Hands-On Learning

    - by Thanos Terentes Printzios
    The Oracle Technology Network (OTN) is excited to invite you to our first Virtual Technology Summit. EMEA – Thursday July 10th / 9am to 1pm BST / 10am – 2pm CET / 12pm to 4pm MSK / GST - Register Now Learn first hand from Oracle ACEs, Java Champions, and Oracle product experts, as they share their insight and expertise on using Oracle technologies to meet today’s IT challenges. This interactive, online event offers four technical tracks, each with a unique focus on specific tools, technologies, and tips in these focus areas. Java – Big Trends and Technologies – Java lets you mine Big Data, build robust apps with HTML5, JavaScript and Java EE, and expand into the Internet of Things. Experts will present and you’ll be able to chat with them live online. Don’t miss out on this great opportunity to learn from some of the best minds in the Java community. Systems – OS Tips and Tricks for Sysadmins – Learn first hand how to configure Oracle Linux to run Oracle Database 11g and 12c, how to use the latest networking capabilities in Oracle Solaris 11, and how to troubleshoot networking problems in Unix and Linux systems. Database – Mastering Oracle Database Management & Development Techniques – Experts will present advanced features and management methods that will help you master your Oracle Database capabilities and drive greater performance, agility and manageability of your IT implementation. This track will build upon your skills with data management, migration, and performance. Middleware – The Architecture of Analytics: Big Time Big Data and Business Intelligence – This track will present a solution architect’s perspective on how business intelligence products in Oracle’s Fusion Middleware family and beyond fit into an effective big data architecture, and present insight and expertise from Oracle ACEs specializing in business Intelligence to help you meet your big data business intelligence challenges. This same content is being offered at 3 different dates listed below, at times convenient for all regions Americas - Wednesday July 9th EMEA – Thursday July 10th APAC English - July 16th 9am to 1pm PST12pm to 4pm  EST1 to 5 pm BRTRegister 9am to 1pm BST10am – 2pm CET12pm to 4pm MSK / GSTRegister IST – 10:00amSG – 12:30pmAEST – 2:30pmRegister The full event agenda is available at https://wikis.oracle.com/display/OTNVirtualTechSummit/Home

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  • Developing wheel reinventing tendencies into a skill as opposed to reluctantly learning wheel-finding skills? [duplicate]

    - by Korey Hinton
    This question already has an answer here: Is reinventing the wheel really all that bad? 20 answers I am more of a high-level wheel reinventor. I definitely prefer to make use of existing API features built into a language and popular third-party frameworks that I know can solve the problem, however when I have a particular problem that I feel capable of solving within a reasonable time I am very reluctant to find someone else's solution. Here are a few reasons why I reinvent: It takes time to learn a new API API restrictions might exist that I don't know about Avoiding re-work of unfamiliar code I am conflicted between doing what I know and shifting to a new technique I don't feel comfortable with. On one hand I feel like following my instincts and getting really good at solving problems, especially ones that I would never challenge myself with if all I did was try to find answers. And on the other hand I feel like I might be missing out on important skills like saving time by finding the right framework and expanding my knowledge by learning how to use a new framework. I guess my question comes down to this: My current attitude is to stick to the built-in API and APIs I know well* and to not spend my time searching github for a solution to a problem I know I can solve myself within a reasonable amount of time. Is that a reasonable balance for a successful programmer? *Obviously I will still look around for new frameworks that save time and solve/simplify difficult problems.

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  • SOA Suite 11g Purging Guide

    - by ShawnBailey
    We now have a single source of truth concerning Purging in My Oracle Support. The material is contained within the SOA 11g Infrastructure Database: Installation, Maintenance and Administration Guide under the 'Purging' tab. All of the previous purge related content for 11g is now deprecated and many of the documents will redirect to this Guide while others simply contain a disclaimer. What does the Guide contain? Summary Overview of Purging. What it does and why it's important Specific information on each release of 11g Available patches for each release of 11g and recommendations How to run the different purge scripts Tips on improving performance How to begin troubleshooting problems with the process How to identify orphaned records Useful reference information Here are a couple of screen shots to help with navigation: Guide Landing Page: (click image for full view) Select the 'Purging' tab: (click image for full view) The left menu contains the following options: Alternative: Database Partitioning What to do on 11gR1 GA (11.1.1.1) What to do on PS1 (11.1.1.2) What to do on PS2 (11.1.1.3) What to do on PS3 (11.1.1.4) What to do on PS4 (11.1.1.5) Overview of PS5 (11.1.1.6) Purging Step by Step Performance Tips Troubleshooting Purge Orphaned Records Reference This resource goes hand in hand with the excellent documents SOA 11g Database Growth Management Strategy and Start Small, Grow Fast available on OTN. The latest product documentation can be found here.

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  • Moving characters on a grid [on hold]

    - by madmax1
    i am developing my first game with C++. My game uses a grid of rectangles. I have a class Board which manages the grid as a whole, initializes the terrain, places/removes characters, etc. It has a 2D vector of a class Field, which handles the Structure of the field, contained Objects, Characters, etc. Field again contains a vector of class Character, which are positioned on the field. Now i want to implement the functionality to move a character on the board, however dont know which is best practice to do so. Should i implement a moveCharacter(character, offset) function in Board, make it search for the character and move it? Or should i implement a function move(offset) in Character? This sure would be nicest, however makes characters necessary to know the board they are on, or the field which in turn knows the board. On the one hand i feel like i should avoid inclusion between classes as much as possible e.g. to increase portability of classes for different projects, on the other hand i think the character.move() functionality is most comfortable for further development. Im pretty new to "bigger" C++ projects and these kind of design questions pop up more and more often lately and i have troubles deciding. Thanks a lot for any advice!

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  • How to decide how backward-compatible my new Mac OS X application should be?

    - by haimg
    I'm currently contemplating writing an OS X version of my Windows software. My Windows application still supports Windows XP, and I know that if I drop support for it now, our customers will cry bloody murder. I'm new to OS X development, and as I learn the technology, APIs, etc., I realized that if I'm going to provide comparable level of backward compatibility (e.g. down to OS X 10.5), I would not be able to use many things that look very useful and relevant in my case (ARC, XPC communications, many others). This is quite different from Windows, in my opinion, where there are very little changed between Windows XP and Windows 7 from desktop application developer's standpoint. So, on one hand, it seems like a complete waste to stick to 2007 or 2009-level API in 2012. On the other hand, according to NetMarketShare report and Stat Owl report Mac OS X 10.5 and 10.6 market share is still 11% and 35%-40% respectively. However, I'm not sure if these older OS users are my target audience (buyers of software utilities) if they didn't bother to upgrade their OS... My question: Are there any other reasons I should take into account when deciding if I target 10.5 or 10.6 or 10.7 for a new application?

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  • Entity system in Lua, communication with C++ and level editor. Need advice.

    - by Notbad
    Hi!, I know this is a really difficult subject. I have been reading a lot this days about Entity systems, etc... And now I'm ready to ask some questions (if you don't mind answering them) because I'm really messed. First of all, I have a 2D basic editor written in Qt, and I'm in the process of adding entitiy edition. I want the editor to be able to receive RTTI information from entities to change properties, create some logic being able to link published events to published actions (Ex:A level activate event throws a door open action), etc... Because all of this I guess my entity system should be written in scripting, in my case Lua. In the other hand I want to use a component based design for my entities, and here starts my questions: 1) Should I define my componentes en C++? If I do this en C++ won't I loose all the RTTI information I want for my editor?. In the other hand, I use box2d for physics, if I define all my components in script won't it be a lot of work to expose third party libs to lua? 2) Where should I place the messa system for my game engine? Lua? C++?. I'm tempted to just have C++ object to behave as servers, offering services to lua business logic. Things like physics system, rendering system, input system, World class, etc... And for all the other things, lua. Creation/Composition of entities based on components, game logic, etc... Could anyone give any insight on how to accomplish this? And what aproach is better?. Thanks in advance, HexDump.

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  • How to cut the line between quality and time?

    - by m3th0dman
    On one hand, I have been taught by various software engineering books ([1] as example) that my job as a programmer is to make the best possible software: great design, flexibility, to be easily maintained etc. One the other hand although I realize that I actually write software for money and not for entertainment, although is very nice to write good code and plan ahead and refactor after writing and ... I wonder if it is always best for the business (after all we should be responsible). Is the business always benefiting from a best code? Maybe I'm over-engineering something, and it's not always useful? So how should I know when to stop in the process to achieving the best possible code? I am sure that experience is something that makes a difference here, but I believe this cannot be the only answer. [1] Uncle Bob's in Clean Code says at page 6 about the fact that: They [managers] may defend the schedule and requirements with passion; but that’s their job. It’s your job to defend the code with equal passion.

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  • Is there a way to save MS Word document as HTML w/o the ms proprietary stuff?

    - by sequoia mcdowell
    So normally I wouldn't use this feature ("Save as Web Page") but I have large documents from clients they just want put on their site as HTML, and formatting it all by hand seems like a waste of time. I have tried "save as webpage" in Word 2007, but it produces all sorts of bad stuff. To wit: <b style='mso-bidi-font-weight:normal'> <span style="mso-spacerun: yes"> as well as a large block of XML formatting info: <!--[if gte mso 9]><xml> <o:DocumentProperties> <o:Subject> </o:Subject> <o:Author> </o:Author> <o:Keywords> </o:Keywords> ... As I said, formatting it all by hand seems like a waste of time, but the way MS exports currently just has too much cruft. Is there a way to export MS Word doc as html without all this?

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  • It is inconsiderate to place editor settings inside code files?

    - by Carlos Campderrós
    I know this is kind of a subjective question, but I'm curious if there's any good reason to place (or not place) editor settings inside code files. I'm thinking in vi modelines, but it is possible that this applies to other editors. In short, a vi modeline is a line inside a file that tells vi how to behave (indent with spaces or tabs, set tabwidth to X, autoindent by default or not, ...) that is placed inside a comment, so it won't affect the program/compiler when running. In a .c file it could be similar to // vim: noai:ts=4:sw=4 On one hand, I think this shouldn't be inside the file, as it is an editor setting and so belongs to an editor configuration file or property. On the other hand, for projects involving developers outside one company (that are not imposed an editor/settings) or collaborators on github/bitbucket/... it is an easy way to avoid breaking the code style (tabs vs spaces for example), but only for the ones that use that editor though. I cannot see any powerful enough reason to decide for or against this practice, so I am in doubt of what to do.

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  • More productive alone than in a team?

    - by Furry
    If I work alone, I used to be superproductive, if I want to be. Running prototypes within a day, something that you can deploy and use within a few days. Not perfect, but good enough. I also had this experience a few times when working directly with someone else. Everybody could do the whole thing, but it was more fun not to do it alone and also quicker. The right two people can take an admittedly not too large project onto new levels. Now at work we have a seven person team and I do not feel nearly as productive. Not even nearly. Certain stuff needs to be checked against something else, which then needs to also take care of some new requirement, which just came in three days ago. All sorts of stuff, mostly important, but often just a technical debt from long ago or misconception or different vocabulary for the same thing or sometimes just a not too technically thought out great idea from someone who wants to have their say, and so on. Digging down the rabbit hole, I think to myself, I could do larger portions of this work faster alone (and somewhat better, too), but it's not my responsibility (someone else gets paid for that), so by design I should not care. But I do, because certain things go hand in hand (as you may experience it, when you done sideprojects on your own). I know this is something Fred Brooks has written about, but still, what's your strategy for staying as productive as you know you could be in the cubicle? Or did you quit for some related reason; and if so where did you go?

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  • Booting off a ZFS root in 14.04

    - by RJVB
    I've been running a Debian derivative (LMDE) on a ZFS root for half a year now. It was created by cloning a regular ext4-based install with all the necessary packages onto a ZFS pool, chrooting into that pool and recreating a grub menu and bootloader. The system uses an ext-3 dedicated /boot partition. I would like to do the same with Ubuntu 14.04, but have encountered several obstacles. There is no Trusty zfs-grub package The default grub package doesn't have ZFS support built in. I found a small bug in the build system responsible for that (report with patch created) and built my own grub packages. The built-in ZFS support is dysfunctional, it does not add the proper arguments to the kernel command line I thus installed the ZoL grub package I also use on my LMDE system, which does give me a correct grub.cfg However, even with that correct grub.cfg, the boot process apparently doesn't retrieve the bootfs parameter from the ZFS pool; instead the variable that's supposed to receive the value remains empty. As a result, initrd tries to load the default pool ("rpool"), which fails of course. I can however import the pool by hand, and complete the process by hand. If memory serves me well, I also had to disable apparmor, to avoid the boot process from blocking after importing the pool. Am I overlooking something? Just for comparison, I installed the Ubuntu 3.13 kernel on my LMDE system, and that works just fine (i.e. the identical kernel and grub binaries allow successful booting without glitches on LMDE but not on Ubuntu).

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  • Virtual Technology Summit Series

    - by CassandraClark-OTN
    The Oracle Technology Network (OTN) is excited to invite you to our first Virtual Technology Summit Series.   Learn first hand from Oracle ACEs, Java Champions, and Oracle product experts, as they share their insight and expertise on using Oracle technologies to meet today’s IT challenges. We are offering three chances to watch and interact with Oracle and community experts.  Register Now by clicking one of the links below! Americas - Wednesday July 9th - 9am to 1pm PT / 12pm to 4pm  ET / 1 to 5 pm BRT EMEA – Thursday July 10th / 9am to 1pm BST / 10am – 2pm CET / 12pm to 4pm MSK / GST APAC English – July 16th / IST – 10:00am / SG – 12:30pm / AEST – 2:30pm ??These interactive, online events offer four technical tracks, each with a unique focus on specific tools, technologies, and tips in these focus areas: Java - Big Trends and Technologies - Java lets you mine Big Data, build robust apps with HTML5, JavaScript and Java EE, and expand into the Internet of Things. Experts will present and you’ll be able to chat with them live online. Don’t miss out on this great opportunity to learn from some of the best minds in the Java community. Systems – OS Tips and Tricks for Sysadmins – Learn first hand how to configure Oracle Linux to run Oracle Database 11g and 12c, how to use the latest networking capabilities in Oracle Solaris 11, and how to troubleshoot networking problems in Unix and Linux systems. Database - Mastering Oracle Database Management & Development Techniques – Oracle ACEs and product team experts will present advanced features and management methods that will help you master your Oracle Database capabilities and drive greater performance, agility and manageability of your IT implementation. This track will build upon your skills with data management, migration, and performance. Middleware - The Architecture of Analytics: Big Time Big Data and Business Intelligence – This track will present a solution architect’s perspective on how business intelligence products in Oracle’s Fusion Middleware family and beyond fit into an effective big data architecture, and present insight and expertise from Oracle ACEs specializing in business Intelligence to help you meet your big data business intelligence challenges.

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  • Is it a good idea to dynamically position and size controls on a form or statically set them?

    - by CrystalBlue
    I've worked mostly with interface building tools such as xCode's Interface Builder and Visual Studio's environment to place forms and position them on screens. But I'm finding that with my latest project, placing controls on the form through a graphical interface is not going to work. This more has to do with the number of custom controls I have to create that I can't visually see before hand. When I first tackled this, I began to position all of my controls relative to the last ones that I created. Doing this had its own pros and cons. On the one hand, this gave me the opportunity to set one number (a margin for example) and when I changed the margin, the controls all sized correctly to one another (such as shortening controls in the center while keeping controls next to the margin the same). But this started to become a spiders-web of code that I knew wouldn't go very far before getting dangerous. Change one number and everything re sizes, but remove one control and you've created many more errors and size problems for all the other controls. It became more surgery then small changes to controls and layout. Is there a good way or maybe a preferred way to determine when I should be using relative or absolute positioning in forms?

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  • Public domain usage of imagery from films? [on hold]

    - by AdamJones
    I'm thinking of starting a small film site, which would begin as a simple blog. Imagery from films I discuss on the site would be vital to the look and feel of this site. Instantly though this makes me wonder about copyright/public domain rights for such imagery. I just wondered if anyone had general or specific advise about using imagery from this industry or another similar situation? On the one hand I know the film industry aggressively tries to protect its IP (fair enough), but on the other hand, surely film companies do release some imagery of their films in stills format into the public domain to simply help their distribution and advertising efforts? I have tried looking on stock photo galleries for images of film stills but only found moviestillsdb.com) which seemed very limited in its results. I've researched a bit about fair usage (http://fairuse.stanford.edu/overview/fair-use/) as well, which I know applies to the USA specifically. This seems to suggest that a still of a film is within these bounds. Still, any constructive advise others may have as a result of experience dealing with imagery, from film or another domain would be greatly appreciated, assuming it isn't "get a lawyer".

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  • Blending the Sketchflow Action

    - by GeekAgilistMercenary
    Started a new Sketchflow Prototype in Expression Blend recently and documented each of the steps.  This blog entry covers some of those steps, which are the basic elements of any prototype.  I will have more information regarding design, prototype creation, and the process of the initial phases for development in the future.  For now, I hope you enjoy this short walk through.  Also, be sure to check out my last quick entry on Sketchflow. I started off with a Sketchflow Project, just like I did in my previous entry (more specifics in that entry about how to manipulate and build out the Sketchflow Map). Once I created the project I setup the following Sketchflow Map. The CoreNavigation is a ComponentScreen setup solely for the page navigation at the top of the screen.  The XAML markup in case you want to create a Component Screen with the same design is included below. <UserControl xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity" xmlns:pb="clr-namespace:Microsoft.Expression.Prototyping.Behavior;assembly=Microsoft.Expression.Prototyping.Interactivity" x:Class="RapidPrototypeSketchScreens.CoreNavigation" d:DesignWidth="624" d:DesignHeight="49" Height="49" Width="624">   <Grid x:Name="LayoutRoot"> <TextBlock HorizontalAlignment="Stretch" Margin="307,3,0,0" Style="{StaticResource TitleCenter-Sketch}" Text="Aütøchart Scorecards" TextWrapping="Wrap"> <i:Interaction.Triggers> <i:EventTrigger EventName="MouseLeftButtonDown"> <pb:NavigateToScreenAction TargetScreen="RapidPrototypeSketchScreens.Screen_1"/> </i:EventTrigger> </i:Interaction.Triggers> </TextBlock> <Button HorizontalAlignment="Left" Margin="164,8,0,11" Style="{StaticResource Button-Sketch}" Width="144" Content="Scorecard"> <i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <pb:NavigateToScreenAction TargetScreen="RapidPrototypeSketchScreens.Screen_1_2"/> </i:EventTrigger> </i:Interaction.Triggers> </Button> <Button HorizontalAlignment="Left" Margin="8,8,0,11" Style="{StaticResource Button-Sketch}" Width="152" Content="Standard Reports"> <i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <pb:NavigateToScreenAction TargetScreen="RapidPrototypeSketchScreens.Screen_1_1"/> </i:EventTrigger> </i:Interaction.Triggers> </Button> </Grid> </UserControl> Now that the CoreNavigation Component Screen is done I built out each of the others.  In each of those screens I included the CoreNavigation Screen (all those little green lines in the image) as the top navigation.  In order to do that, as I created each of the pages I would hover over the CoreNavigation Object in the Sketchflow Map.  When the utilities drawer (the small menu that pops down under a node when you hover over it) shows click on the third little icon and drag it onto the page node you want a navigation screen on. Once I created all the screens I setup the navigation by opening up each screen and right clicking on the objects that needed to point to somewhere else in the prototype. Once I was done with the main page, my Home Navigation Page, it looked something like this in the Expression Blend Designer. I fleshed out each of the additional screens.  Once I was done I wanted to try out the deployment package.  The way to deploy a Sketchflow Prototype is to merely click on File –> Package SketchFlow Project and a prompt will appear.  In the prompt enter what you want the package to be called. I like to see the files generated afterwards too, so I checked the box to see that.  When Expression Blend is done generating everything you’ll have a directory like the one shown below, with all the needed files for deployment. Now these files can be copied or moved to any location for viewing.  One can even copy them (such as via FTP) to a server location to share with others.  Once they are deployed and you run the "TestPage.html" the other features of the Sketchflow Package are available. In the image below I have tagged a few sections to show the Sketchflow Player Features.  To the top left is the navigation, which provides a clearly defined area of movement in a list.  To the center right is the actual prototype application.  I have placed lists of things and made edits.  On the left hand side is the highlight feature, which is available in the Feedback section of the lower left.  On the right hand list I underlined the Autochart with an orange marker, and marked out two list items with a red marker. In the lower left hand side in the Feedback section is also an area to type in your feedback.  This can be useful for time based feedback, when you post this somewhere and want people to provide subsequent follow up feedback. Overall lots of great features, that enable some fairly rapid prototyping with customers.  Once one is familiar with the steps and parts of this Sketchflow Prototype Capabilities it is easy to step through an application without even stopping.  It really is that easy.  So get hold of Expression Blend 3 and get ramped up on Sketchflow, it will pay off in the design phases to do so! Original Entry

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  • Guest Post: Instantiate SharePoint Workflow On Item Deleted

    - by Brian Jackett
    In this post, guest author Lucas Eduardo Silva will walk you through the steps of instantiating a workflow using an item event receiver from a custom list.  The ItemDeleting event will require approval via the workflow. Foreword     As you may have read recently, I injured my right hand and have had it in a cast for the past 3 weeks.  Due to this I planned to reduce my blogging while my hand heals.  As luck would have it, I was actually approached by someone who asked if they could be a guest author on my blog.  I’ve never had a guest author, but considering my injury now seemed like as good a time as ever to try it out. About the Guest Author     Lucas Eduardo Silva (email) works for CPM Braxis, a sibling company to my employer Sogeti in the CapGemini family.  Lucas and I exchanged emails a few times after one of my  recent posts and continued into various topics.  When I posted that I had injured my hand, Lucas mentioned that he had a post idea that he would like to publish and asked if it could be published on my blog.  The below content is the result of that collaboration. The Problem     Lucas has a big problem.  He has a workflow that he wants to fire every time an item is deleted from a custom list. He has already created the association in the "item deleting event", but needs to approve the deletion but the workflow is finishing first. Lucas put an onWorkflowItemChanged wait for the change of status approval, but it is not being hit. The Solution Note: This solution assumes you have the Visual Studio Extensions for Windows SharePoint Services (VSeWSS) installed to access the SharePoint project templates within VIsual Studio. 1 - Create a workflow that will be activated by ItemEventReceiver. 2 - Create the list by Visual Studio clicking in File -> New -> Project. Select SharePoint, then List Definition. 3 - Select the type of document to be created. List, Document Library, Wiki, Tasks, etc.. 4 - Visual Studio creates the file ItemEventReceiver.cs with all possible events in a list. 5 – In the workflow project, open the workflow.xml and copy the ID. 6 - Uncomment the ItemDeleting and insert the following code by replacing the ID that you copied earlier.   //Cancel the Exclusion properties.Cancel = true;   //Activating Exclusion Workflow SPWorkflowManager workflowManager = properties.ListItem.Web.Site.WorkflowManager;   SPWorkflowAssociation wfAssociation = properties.ListItem.ParentList.WorkflowAssociations. GetAssociationByBaseID(new Guid("37b5aea8-792a-4ded-be25-d283d9fe1f9d"));   workflowManager.StartWorkflow(properties.ListItem, wfAssociation, wfAssociation.AssociationData, true);   properties.Status = SPEventReceiverStatus.CancelNoError;   7 - properties.Cancel cancels the event being activated and executes the code that is inside the event. In the example, it cancels the deletion of the item to start the workflow that will be active as an association list with the workflow ID. 8 - Create and deploy the workflow and the list for SharePoint. 9 - Create a list through the model that was created. 10 - Enable the workflow in the list and Congratulations! Every time you try to delete the item the workflow is activated. TIP: If you really want to delete the item after the workflow is done you will have to delete the item by the workflow.   this.workflowProperties.Site.AllowUnsafeUpdates = true; this.workflowProperties.Item.Delete(); this.workflowProperties.List.Update();   Conclusion     In this guest post Lucas took you through the steps of creating an item deletion approval workflow with an event receiver.  This was also the first time I’ve had a guest author on this blog.  Many thanks to Lucas for putting together this content and offering it.  I haven’t decided how I’d handle future guest authors, mostly because I don’t know if there are others who would want to submit content.  If you do have something that you would like to guest author on my blog feel free to drop me a line and we can discuss.  As a disclaimer, there are no guarantees that it will be published though.  For now enjoy Lucas’ post and look for my return to regular blogging soon.         -Frog Out   <Update 1> If you wish to contact Lucas you can reach him at [email protected] </Update 1>

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  • PanelGridLayout - A Layout Revolution

    - by Duncan Mills
    With the most recent 11.1.2 patchset (11.1.2.3) there has been a lot of excitement around ADF Essentials (and rightly so), however, in all the fuss I didn't want an even more significant change to get missed - yes you read that correctly, a more significant change! I'm talking about the new panelGridLayout component, I can confidently say that this one of the most revolutionary components that we've introduced in 11g, even though it sounds rather boring. To be totally accurate, panelGrid was introduced in 11.1.2.2 but without any presence in the component palette or other design time support, so it was largely missed unless you read the release notes. However in this latest patchset it's finally front and center. Its time to explore - we (really) need to talk about layout.  Let's face it,with ADF Faces rich client, layout is a rather arcane pursuit, once you are a layout master, all bow before you, but it's more of an art than a science, and it is often, in fact, way too difficult to achieve what should (apparently) be a pretty simple. Here's a great example, it's a homework assignment I set for folks I'm teaching this stuff to:  The requirements for this layout are: The header is 80px high, the footer is 30px. These are both fixed.  The first section of the header containing the logo is 180px wide The logo is centered within the top left hand corner of the header  The title text is start aligned in the center zone of the header and will wrap if the browser window is narrowed. It should be aligned in the center of the vertical space  The about link is anchored to the right hand side of the browser with a 20px gap and again is center aligned vertically. It will move as the browser window is reduced in width. The footer has a right aligned copyright statement, again middle aligned within a 30px high footer region and with a 20px buffer to the right hand edge. It will move as the browser window is reduced in width. All remaining space is given to a central zone, which, in this case contains a panelSplitter. Expect that at some point in time you'll need a separate messages line in the center of the footer.  In the homework assigment I set I also stipulate that no inlineStyles can be used to control alignment or margins and no use of other taglibs (e.g. JSF HTML or Trinidad HTML). So, if we take this purist approach, that basic page layout (in my stock solution) requires 3 panelStretchLayouts, 5 panelGroupLayouts and 4 spacers - not including the spacer I use for the logo and the contents of the central zone splitter - phew! The point is that even a seemingly simple layout needs a bit of thinking about, particulatly when you consider strechting and browser re-size behavior. In fact, this little sample actually teaches you much of what you need to know to become vaguely competant at layouts in the framework. The underlying result of "the way things are" is that most of us reach for panelStretchLayout before even finishing the first sip of coffee as we embark on a new page design. In fact most pages you will see in any moderately complex ADF page will basically be nested panelStretchLayouts and panelGroupLayouts, sometimes many, many levels deep. So this is a problem, we've known this for some time and now we have a good solution. (I should point out that the oft-used Trinidad trh tags are not a particularly good solution as you're tie-ing yourself to an HTML table based layout in that case with a host of attendent issues in resize and bi-di behavior, but I digress.) So, tadaaa, I give to you panelGridLayout. PanelGrid, as the name suggests takes a grid like (dare I say slightly gridbag-like) approach to layout, dividing your layout into rows and colums with margins, sizing, stretch behaviour, colspans and rowspans all rolled in, all without the use of inlineStyle. As such, it provides for a much more powerful and consise way of defining a layout such as the one above that is actually simpler and much more logical to design. The basic building blocks are the panelGridLayout itself, gridRow and gridCell. Your content sits inside the cells inside the rows, all helpfully allowing both streching, valign and halign definitions without the need to nest further panelGroupLayouts. So much simpler!  If I break down the homework example above my nested comglomorate of 12 containers and spacers can be condensed down into a single panelGrid with 3 rows and 5 cell definitions (39 lines of source reduced to 24 in the case of the sample). What's more, the actual runtime representation in the browser DOM is much, much simpler, and clean, with basically one DIV per cell (Note that just because the panelGridLayout semantics looks like an HTML table does not mean that it's rendered that way!) . Another hidden benefit is the runtime cost. Because we can use a single layout to achieve much more complex geometries the client side layout code inside the browser is having to work a lot less. This will be a real benefit if your application needs to run on lower powered clients such as netbooks or tablets. So, it's time, if you're on 11.1.2.2 or above, to smile warmly at your panelStretchLayouts, wrap the blanket around it's knees and wheel it off to the Sunset Retirement Home for a well deserved rest. There's a new kid on the block and it wants to be your friend. 

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  • How John Got 15x Improvement Without Really Trying

    - by rchrd
    The following article was published on a Sun Microsystems website a number of years ago by John Feo. It is still useful and worth preserving. So I'm republishing it here.  How I Got 15x Improvement Without Really Trying John Feo, Sun Microsystems Taking ten "personal" program codes used in scientific and engineering research, the author was able to get from 2 to 15 times performance improvement easily by applying some simple general optimization techniques. Introduction Scientific research based on computer simulation depends on the simulation for advancement. The research can advance only as fast as the computational codes can execute. The codes' efficiency determines both the rate and quality of results. In the same amount of time, a faster program can generate more results and can carry out a more detailed simulation of physical phenomena than a slower program. Highly optimized programs help science advance quickly and insure that monies supporting scientific research are used as effectively as possible. Scientific computer codes divide into three broad categories: ISV, community, and personal. ISV codes are large, mature production codes developed and sold commercially. The codes improve slowly over time both in methods and capabilities, and they are well tuned for most vendor platforms. Since the codes are mature and complex, there are few opportunities to improve their performance solely through code optimization. Improvements of 10% to 15% are typical. Examples of ISV codes are DYNA3D, Gaussian, and Nastran. Community codes are non-commercial production codes used by a particular research field. Generally, they are developed and distributed by a single academic or research institution with assistance from the community. Most users just run the codes, but some develop new methods and extensions that feed back into the general release. The codes are available on most vendor platforms. Since these codes are younger than ISV codes, there are more opportunities to optimize the source code. Improvements of 50% are not unusual. Examples of community codes are AMBER, CHARM, BLAST, and FASTA. Personal codes are those written by single users or small research groups for their own use. These codes are not distributed, but may be passed from professor-to-student or student-to-student over several years. They form the primordial ocean of applications from which community and ISV codes emerge. Government research grants pay for the development of most personal codes. This paper reports on the nature and performance of this class of codes. Over the last year, I have looked at over two dozen personal codes from more than a dozen research institutions. The codes cover a variety of scientific fields, including astronomy, atmospheric sciences, bioinformatics, biology, chemistry, geology, and physics. The sources range from a few hundred lines to more than ten thousand lines, and are written in Fortran, Fortran 90, C, and C++. For the most part, the codes are modular, documented, and written in a clear, straightforward manner. They do not use complex language features, advanced data structures, programming tricks, or libraries. I had little trouble understanding what the codes did or how data structures were used. Most came with a makefile. Surprisingly, only one of the applications is parallel. All developers have access to parallel machines, so availability is not an issue. Several tried to parallelize their applications, but stopped after encountering difficulties. Lack of education and a perception that parallelism is difficult prevented most from trying. I parallelized several of the codes using OpenMP, and did not judge any of the codes as difficult to parallelize. Even more surprising than the lack of parallelism is the inefficiency of the codes. I was able to get large improvements in performance in a matter of a few days applying simple optimization techniques. Table 1 lists ten representative codes [names and affiliation are omitted to preserve anonymity]. Improvements on one processor range from 2x to 15.5x with a simple average of 4.75x. I did not use sophisticated performance tools or drill deep into the program's execution character as one would do when tuning ISV or community codes. Using only a profiler and source line timers, I identified inefficient sections of code and improved their performance by inspection. The changes were at a high level. I am sure there is another factor of 2 or 3 in each code, and more if the codes are parallelized. The study’s results show that personal scientific codes are running many times slower than they should and that the problem is pervasive. Computational scientists are not sloppy programmers; however, few are trained in the art of computer programming or code optimization. I found that most have a working knowledge of some programming language and standard software engineering practices; but they do not know, or think about, how to make their programs run faster. They simply do not know the standard techniques used to make codes run faster. In fact, they do not even perceive that such techniques exist. The case studies described in this paper show that applying simple, well known techniques can significantly increase the performance of personal codes. It is important that the scientific community and the Government agencies that support scientific research find ways to better educate academic scientific programmers. The inefficiency of their codes is so bad that it is retarding both the quality and progress of scientific research. # cacheperformance redundantoperations loopstructures performanceimprovement 1 x x 15.5 2 x 2.8 3 x x 2.5 4 x 2.1 5 x x 2.0 6 x 5.0 7 x 5.8 8 x 6.3 9 2.2 10 x x 3.3 Table 1 — Area of improvement and performance gains of 10 codes The remainder of the paper is organized as follows: sections 2, 3, and 4 discuss the three most common sources of inefficiencies in the codes studied. These are cache performance, redundant operations, and loop structures. Each section includes several examples. The last section summaries the work and suggests a possible solution to the issues raised. Optimizing cache performance Commodity microprocessor systems use caches to increase memory bandwidth and reduce memory latencies. Typical latencies from processor to L1, L2, local, and remote memory are 3, 10, 50, and 200 cycles, respectively. Moreover, bandwidth falls off dramatically as memory distances increase. Programs that do not use cache effectively run many times slower than programs that do. When optimizing for cache, the biggest performance gains are achieved by accessing data in cache order and reusing data to amortize the overhead of cache misses. Secondary considerations are prefetching, associativity, and replacement; however, the understanding and analysis required to optimize for the latter are probably beyond the capabilities of the non-expert. Much can be gained simply by accessing data in the correct order and maximizing data reuse. 6 out of the 10 codes studied here benefited from such high level optimizations. Array Accesses The most important cache optimization is the most basic: accessing Fortran array elements in column order and C array elements in row order. Four of the ten codes—1, 2, 4, and 10—got it wrong. Compilers will restructure nested loops to optimize cache performance, but may not do so if the loop structure is too complex, or the loop body includes conditionals, complex addressing, or function calls. In code 1, the compiler failed to invert a key loop because of complex addressing do I = 0, 1010, delta_x IM = I - delta_x IP = I + delta_x do J = 5, 995, delta_x JM = J - delta_x JP = J + delta_x T1 = CA1(IP, J) + CA1(I, JP) T2 = CA1(IM, J) + CA1(I, JM) S1 = T1 + T2 - 4 * CA1(I, J) CA(I, J) = CA1(I, J) + D * S1 end do end do In code 2, the culprit is conditionals do I = 1, N do J = 1, N If (IFLAG(I,J) .EQ. 0) then T1 = Value(I, J-1) T2 = Value(I-1, J) T3 = Value(I, J) T4 = Value(I+1, J) T5 = Value(I, J+1) Value(I,J) = 0.25 * (T1 + T2 + T5 + T4) Delta = ABS(T3 - Value(I,J)) If (Delta .GT. MaxDelta) MaxDelta = Delta endif enddo enddo I fixed both programs by inverting the loops by hand. Code 10 has three-dimensional arrays and triply nested loops. The structure of the most computationally intensive loops is too complex to invert automatically or by hand. The only practical solution is to transpose the arrays so that the dimension accessed by the innermost loop is in cache order. The arrays can be transposed at construction or prior to entering a computationally intensive section of code. The former requires all array references to be modified, while the latter is cost effective only if the cost of the transpose is amortized over many accesses. I used the second approach to optimize code 10. Code 5 has four-dimensional arrays and loops are nested four deep. For all of the reasons cited above the compiler is not able to restructure three key loops. Assume C arrays and let the four dimensions of the arrays be i, j, k, and l. In the original code, the index structure of the three loops is L1: for i L2: for i L3: for i for l for l for j for k for j for k for j for k for l So only L3 accesses array elements in cache order. L1 is a very complex loop—much too complex to invert. I brought the loop into cache alignment by transposing the second and fourth dimensions of the arrays. Since the code uses a macro to compute all array indexes, I effected the transpose at construction and changed the macro appropriately. The dimensions of the new arrays are now: i, l, k, and j. L3 is a simple loop and easily inverted. L2 has a loop-carried scalar dependence in k. By promoting the scalar name that carries the dependence to an array, I was able to invert the third and fourth subloops aligning the loop with cache. Code 5 is by far the most difficult of the four codes to optimize for array accesses; but the knowledge required to fix the problems is no more than that required for the other codes. I would judge this code at the limits of, but not beyond, the capabilities of appropriately trained computational scientists. Array Strides When a cache miss occurs, a line (64 bytes) rather than just one word is loaded into the cache. If data is accessed stride 1, than the cost of the miss is amortized over 8 words. Any stride other than one reduces the cost savings. Two of the ten codes studied suffered from non-unit strides. The codes represent two important classes of "strided" codes. Code 1 employs a multi-grid algorithm to reduce time to convergence. The grids are every tenth, fifth, second, and unit element. Since time to convergence is inversely proportional to the distance between elements, coarse grids converge quickly providing good starting values for finer grids. The better starting values further reduce the time to convergence. The downside is that grids of every nth element, n > 1, introduce non-unit strides into the computation. In the original code, much of the savings of the multi-grid algorithm were lost due to this problem. I eliminated the problem by compressing (copying) coarse grids into continuous memory, and rewriting the computation as a function of the compressed grid. On convergence, I copied the final values of the compressed grid back to the original grid. The savings gained from unit stride access of the compressed grid more than paid for the cost of copying. Using compressed grids, the loop from code 1 included in the previous section becomes do j = 1, GZ do i = 1, GZ T1 = CA(i+0, j-1) + CA(i-1, j+0) T4 = CA1(i+1, j+0) + CA1(i+0, j+1) S1 = T1 + T4 - 4 * CA1(i+0, j+0) CA(i+0, j+0) = CA1(i+0, j+0) + DD * S1 enddo enddo where CA and CA1 are compressed arrays of size GZ. Code 7 traverses a list of objects selecting objects for later processing. The labels of the selected objects are stored in an array. The selection step has unit stride, but the processing steps have irregular stride. A fix is to save the parameters of the selected objects in temporary arrays as they are selected, and pass the temporary arrays to the processing functions. The fix is practical if the same parameters are used in selection as in processing, or if processing comprises a series of distinct steps which use overlapping subsets of the parameters. Both conditions are true for code 7, so I achieved significant improvement by copying parameters to temporary arrays during selection. Data reuse In the previous sections, we optimized for spatial locality. It is also important to optimize for temporal locality. Once read, a datum should be used as much as possible before it is forced from cache. Loop fusion and loop unrolling are two techniques that increase temporal locality. Unfortunately, both techniques increase register pressure—as loop bodies become larger, the number of registers required to hold temporary values grows. Once register spilling occurs, any gains evaporate quickly. For multiprocessors with small register sets or small caches, the sweet spot can be very small. In the ten codes presented here, I found no opportunities for loop fusion and only two opportunities for loop unrolling (codes 1 and 3). In code 1, unrolling the outer and inner loop one iteration increases the number of result values computed by the loop body from 1 to 4, do J = 1, GZ-2, 2 do I = 1, GZ-2, 2 T1 = CA1(i+0, j-1) + CA1(i-1, j+0) T2 = CA1(i+1, j-1) + CA1(i+0, j+0) T3 = CA1(i+0, j+0) + CA1(i-1, j+1) T4 = CA1(i+1, j+0) + CA1(i+0, j+1) T5 = CA1(i+2, j+0) + CA1(i+1, j+1) T6 = CA1(i+1, j+1) + CA1(i+0, j+2) T7 = CA1(i+2, j+1) + CA1(i+1, j+2) S1 = T1 + T4 - 4 * CA1(i+0, j+0) S2 = T2 + T5 - 4 * CA1(i+1, j+0) S3 = T3 + T6 - 4 * CA1(i+0, j+1) S4 = T4 + T7 - 4 * CA1(i+1, j+1) CA(i+0, j+0) = CA1(i+0, j+0) + DD * S1 CA(i+1, j+0) = CA1(i+1, j+0) + DD * S2 CA(i+0, j+1) = CA1(i+0, j+1) + DD * S3 CA(i+1, j+1) = CA1(i+1, j+1) + DD * S4 enddo enddo The loop body executes 12 reads, whereas as the rolled loop shown in the previous section executes 20 reads to compute the same four values. In code 3, two loops are unrolled 8 times and one loop is unrolled 4 times. Here is the before for (k = 0; k < NK[u]; k++) { sum = 0.0; for (y = 0; y < NY; y++) { sum += W[y][u][k] * delta[y]; } backprop[i++]=sum; } and after code for (k = 0; k < KK - 8; k+=8) { sum0 = 0.0; sum1 = 0.0; sum2 = 0.0; sum3 = 0.0; sum4 = 0.0; sum5 = 0.0; sum6 = 0.0; sum7 = 0.0; for (y = 0; y < NY; y++) { sum0 += W[y][0][k+0] * delta[y]; sum1 += W[y][0][k+1] * delta[y]; sum2 += W[y][0][k+2] * delta[y]; sum3 += W[y][0][k+3] * delta[y]; sum4 += W[y][0][k+4] * delta[y]; sum5 += W[y][0][k+5] * delta[y]; sum6 += W[y][0][k+6] * delta[y]; sum7 += W[y][0][k+7] * delta[y]; } backprop[k+0] = sum0; backprop[k+1] = sum1; backprop[k+2] = sum2; backprop[k+3] = sum3; backprop[k+4] = sum4; backprop[k+5] = sum5; backprop[k+6] = sum6; backprop[k+7] = sum7; } for one of the loops unrolled 8 times. Optimizing for temporal locality is the most difficult optimization considered in this paper. The concepts are not difficult, but the sweet spot is small. Identifying where the program can benefit from loop unrolling or loop fusion is not trivial. Moreover, it takes some effort to get it right. Still, educating scientific programmers about temporal locality and teaching them how to optimize for it will pay dividends. Reducing instruction count Execution time is a function of instruction count. Reduce the count and you usually reduce the time. The best solution is to use a more efficient algorithm; that is, an algorithm whose order of complexity is smaller, that converges quicker, or is more accurate. Optimizing source code without changing the algorithm yields smaller, but still significant, gains. This paper considers only the latter because the intent is to study how much better codes can run if written by programmers schooled in basic code optimization techniques. The ten codes studied benefited from three types of "instruction reducing" optimizations. The two most prevalent were hoisting invariant memory and data operations out of inner loops. The third was eliminating unnecessary data copying. The nature of these inefficiencies is language dependent. Memory operations The semantics of C make it difficult for the compiler to determine all the invariant memory operations in a loop. The problem is particularly acute for loops in functions since the compiler may not know the values of the function's parameters at every call site when compiling the function. Most compilers support pragmas to help resolve ambiguities; however, these pragmas are not comprehensive and there is no standard syntax. To guarantee that invariant memory operations are not executed repetitively, the user has little choice but to hoist the operations by hand. The problem is not as severe in Fortran programs because in the absence of equivalence statements, it is a violation of the language's semantics for two names to share memory. Codes 3 and 5 are C programs. In both cases, the compiler did not hoist all invariant memory operations from inner loops. Consider the following loop from code 3 for (y = 0; y < NY; y++) { i = 0; for (u = 0; u < NU; u++) { for (k = 0; k < NK[u]; k++) { dW[y][u][k] += delta[y] * I1[i++]; } } } Since dW[y][u] can point to the same memory space as delta for one or more values of y and u, assignment to dW[y][u][k] may change the value of delta[y]. In reality, dW and delta do not overlap in memory, so I rewrote the loop as for (y = 0; y < NY; y++) { i = 0; Dy = delta[y]; for (u = 0; u < NU; u++) { for (k = 0; k < NK[u]; k++) { dW[y][u][k] += Dy * I1[i++]; } } } Failure to hoist invariant memory operations may be due to complex address calculations. If the compiler can not determine that the address calculation is invariant, then it can hoist neither the calculation nor the associated memory operations. As noted above, code 5 uses a macro to address four-dimensional arrays #define MAT4D(a,q,i,j,k) (double *)((a)->data + (q)*(a)->strides[0] + (i)*(a)->strides[3] + (j)*(a)->strides[2] + (k)*(a)->strides[1]) The macro is too complex for the compiler to understand and so, it does not identify any subexpressions as loop invariant. The simplest way to eliminate the address calculation from the innermost loop (over i) is to define a0 = MAT4D(a,q,0,j,k) before the loop and then replace all instances of *MAT4D(a,q,i,j,k) in the loop with a0[i] A similar problem appears in code 6, a Fortran program. The key loop in this program is do n1 = 1, nh nx1 = (n1 - 1) / nz + 1 nz1 = n1 - nz * (nx1 - 1) do n2 = 1, nh nx2 = (n2 - 1) / nz + 1 nz2 = n2 - nz * (nx2 - 1) ndx = nx2 - nx1 ndy = nz2 - nz1 gxx = grn(1,ndx,ndy) gyy = grn(2,ndx,ndy) gxy = grn(3,ndx,ndy) balance(n1,1) = balance(n1,1) + (force(n2,1) * gxx + force(n2,2) * gxy) * h1 balance(n1,2) = balance(n1,2) + (force(n2,1) * gxy + force(n2,2) * gyy)*h1 end do end do The programmer has written this loop well—there are no loop invariant operations with respect to n1 and n2. However, the loop resides within an iterative loop over time and the index calculations are independent with respect to time. Trading space for time, I precomputed the index values prior to the entering the time loop and stored the values in two arrays. I then replaced the index calculations with reads of the arrays. Data operations Ways to reduce data operations can appear in many forms. Implementing a more efficient algorithm produces the biggest gains. The closest I came to an algorithm change was in code 4. This code computes the inner product of K-vectors A(i) and B(j), 0 = i < N, 0 = j < M, for most values of i and j. Since the program computes most of the NM possible inner products, it is more efficient to compute all the inner products in one triply-nested loop rather than one at a time when needed. The savings accrue from reading A(i) once for all B(j) vectors and from loop unrolling. for (i = 0; i < N; i+=8) { for (j = 0; j < M; j++) { sum0 = 0.0; sum1 = 0.0; sum2 = 0.0; sum3 = 0.0; sum4 = 0.0; sum5 = 0.0; sum6 = 0.0; sum7 = 0.0; for (k = 0; k < K; k++) { sum0 += A[i+0][k] * B[j][k]; sum1 += A[i+1][k] * B[j][k]; sum2 += A[i+2][k] * B[j][k]; sum3 += A[i+3][k] * B[j][k]; sum4 += A[i+4][k] * B[j][k]; sum5 += A[i+5][k] * B[j][k]; sum6 += A[i+6][k] * B[j][k]; sum7 += A[i+7][k] * B[j][k]; } C[i+0][j] = sum0; C[i+1][j] = sum1; C[i+2][j] = sum2; C[i+3][j] = sum3; C[i+4][j] = sum4; C[i+5][j] = sum5; C[i+6][j] = sum6; C[i+7][j] = sum7; }} This change requires knowledge of a typical run; i.e., that most inner products are computed. The reasons for the change, however, derive from basic optimization concepts. It is the type of change easily made at development time by a knowledgeable programmer. In code 5, we have the data version of the index optimization in code 6. Here a very expensive computation is a function of the loop indices and so cannot be hoisted out of the loop; however, the computation is invariant with respect to an outer iterative loop over time. We can compute its value for each iteration of the computation loop prior to entering the time loop and save the values in an array. The increase in memory required to store the values is small in comparison to the large savings in time. The main loop in Code 8 is doubly nested. The inner loop includes a series of guarded computations; some are a function of the inner loop index but not the outer loop index while others are a function of the outer loop index but not the inner loop index for (j = 0; j < N; j++) { for (i = 0; i < M; i++) { r = i * hrmax; R = A[j]; temp = (PRM[3] == 0.0) ? 1.0 : pow(r, PRM[3]); high = temp * kcoeff * B[j] * PRM[2] * PRM[4]; low = high * PRM[6] * PRM[6] / (1.0 + pow(PRM[4] * PRM[6], 2.0)); kap = (R > PRM[6]) ? high * R * R / (1.0 + pow(PRM[4]*r, 2.0) : low * pow(R/PRM[6], PRM[5]); < rest of loop omitted > }} Note that the value of temp is invariant to j. Thus, we can hoist the computation for temp out of the loop and save its values in an array. for (i = 0; i < M; i++) { r = i * hrmax; TEMP[i] = pow(r, PRM[3]); } [N.B. – the case for PRM[3] = 0 is omitted and will be reintroduced later.] We now hoist out of the inner loop the computations invariant to i. Since the conditional guarding the value of kap is invariant to i, it behooves us to hoist the computation out of the inner loop, thereby executing the guard once rather than M times. The final version of the code is for (j = 0; j < N; j++) { R = rig[j] / 1000.; tmp1 = kcoeff * par[2] * beta[j] * par[4]; tmp2 = 1.0 + (par[4] * par[4] * par[6] * par[6]); tmp3 = 1.0 + (par[4] * par[4] * R * R); tmp4 = par[6] * par[6] / tmp2; tmp5 = R * R / tmp3; tmp6 = pow(R / par[6], par[5]); if ((par[3] == 0.0) && (R > par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * tmp5; } else if ((par[3] == 0.0) && (R <= par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * tmp4 * tmp6; } else if ((par[3] != 0.0) && (R > par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * TEMP[i] * tmp5; } else if ((par[3] != 0.0) && (R <= par[6])) { for (i = 1; i <= imax1; i++) KAP[i] = tmp1 * TEMP[i] * tmp4 * tmp6; } for (i = 0; i < M; i++) { kap = KAP[i]; r = i * hrmax; < rest of loop omitted > } } Maybe not the prettiest piece of code, but certainly much more efficient than the original loop, Copy operations Several programs unnecessarily copy data from one data structure to another. This problem occurs in both Fortran and C programs, although it manifests itself differently in the two languages. Code 1 declares two arrays—one for old values and one for new values. At the end of each iteration, the array of new values is copied to the array of old values to reset the data structures for the next iteration. This problem occurs in Fortran programs not included in this study and in both Fortran 77 and Fortran 90 code. Introducing pointers to the arrays and swapping pointer values is an obvious way to eliminate the copying; but pointers is not a feature that many Fortran programmers know well or are comfortable using. An easy solution not involving pointers is to extend the dimension of the value array by 1 and use the last dimension to differentiate between arrays at different times. For example, if the data space is N x N, declare the array (N, N, 2). Then store the problem’s initial values in (_, _, 2) and define the scalar names new = 2 and old = 1. At the start of each iteration, swap old and new to reset the arrays. The old–new copy problem did not appear in any C program. In programs that had new and old values, the code swapped pointers to reset data structures. Where unnecessary coping did occur is in structure assignment and parameter passing. Structures in C are handled much like scalars. Assignment causes the data space of the right-hand name to be copied to the data space of the left-hand name. Similarly, when a structure is passed to a function, the data space of the actual parameter is copied to the data space of the formal parameter. If the structure is large and the assignment or function call is in an inner loop, then copying costs can grow quite large. While none of the ten programs considered here manifested this problem, it did occur in programs not included in the study. A simple fix is always to refer to structures via pointers. Optimizing loop structures Since scientific programs spend almost all their time in loops, efficient loops are the key to good performance. Conditionals, function calls, little instruction level parallelism, and large numbers of temporary values make it difficult for the compiler to generate tightly packed, highly efficient code. Conditionals and function calls introduce jumps that disrupt code flow. Users should eliminate or isolate conditionls to their own loops as much as possible. Often logical expressions can be substituted for if-then-else statements. For example, code 2 includes the following snippet MaxDelta = 0.0 do J = 1, N do I = 1, M < code omitted > Delta = abs(OldValue ? NewValue) if (Delta > MaxDelta) MaxDelta = Delta enddo enddo if (MaxDelta .gt. 0.001) goto 200 Since the only use of MaxDelta is to control the jump to 200 and all that matters is whether or not it is greater than 0.001, I made MaxDelta a boolean and rewrote the snippet as MaxDelta = .false. do J = 1, N do I = 1, M < code omitted > Delta = abs(OldValue ? NewValue) MaxDelta = MaxDelta .or. (Delta .gt. 0.001) enddo enddo if (MaxDelta) goto 200 thereby, eliminating the conditional expression from the inner loop. A microprocessor can execute many instructions per instruction cycle. Typically, it can execute one or more memory, floating point, integer, and jump operations. To be executed simultaneously, the operations must be independent. Thick loops tend to have more instruction level parallelism than thin loops. Moreover, they reduce memory traffice by maximizing data reuse. Loop unrolling and loop fusion are two techniques to increase the size of loop bodies. Several of the codes studied benefitted from loop unrolling, but none benefitted from loop fusion. This observation is not too surpising since it is the general tendency of programmers to write thick loops. As loops become thicker, the number of temporary values grows, increasing register pressure. If registers spill, then memory traffic increases and code flow is disrupted. A thick loop with many temporary values may execute slower than an equivalent series of thin loops. The biggest gain will be achieved if the thick loop can be split into a series of independent loops eliminating the need to write and read temporary arrays. I found such an occasion in code 10 where I split the loop do i = 1, n do j = 1, m A24(j,i)= S24(j,i) * T24(j,i) + S25(j,i) * U25(j,i) B24(j,i)= S24(j,i) * T25(j,i) + S25(j,i) * U24(j,i) A25(j,i)= S24(j,i) * C24(j,i) + S25(j,i) * V24(j,i) B25(j,i)= S24(j,i) * U25(j,i) + S25(j,i) * V25(j,i) C24(j,i)= S26(j,i) * T26(j,i) + S27(j,i) * U26(j,i) D24(j,i)= S26(j,i) * T27(j,i) + S27(j,i) * V26(j,i) C25(j,i)= S27(j,i) * S28(j,i) + S26(j,i) * U28(j,i) D25(j,i)= S27(j,i) * T28(j,i) + S26(j,i) * V28(j,i) end do end do into two disjoint loops do i = 1, n do j = 1, m A24(j,i)= S24(j,i) * T24(j,i) + S25(j,i) * U25(j,i) B24(j,i)= S24(j,i) * T25(j,i) + S25(j,i) * U24(j,i) A25(j,i)= S24(j,i) * C24(j,i) + S25(j,i) * V24(j,i) B25(j,i)= S24(j,i) * U25(j,i) + S25(j,i) * V25(j,i) end do end do do i = 1, n do j = 1, m C24(j,i)= S26(j,i) * T26(j,i) + S27(j,i) * U26(j,i) D24(j,i)= S26(j,i) * T27(j,i) + S27(j,i) * V26(j,i) C25(j,i)= S27(j,i) * S28(j,i) + S26(j,i) * U28(j,i) D25(j,i)= S27(j,i) * T28(j,i) + S26(j,i) * V28(j,i) end do end do Conclusions Over the course of the last year, I have had the opportunity to work with over two dozen academic scientific programmers at leading research universities. Their research interests span a broad range of scientific fields. Except for two programs that relied almost exclusively on library routines (matrix multiply and fast Fourier transform), I was able to improve significantly the single processor performance of all codes. Improvements range from 2x to 15.5x with a simple average of 4.75x. Changes to the source code were at a very high level. I did not use sophisticated techniques or programming tools to discover inefficiencies or effect the changes. Only one code was parallel despite the availability of parallel systems to all developers. Clearly, we have a problem—personal scientific research codes are highly inefficient and not running parallel. The developers are unaware of simple optimization techniques to make programs run faster. They lack education in the art of code optimization and parallel programming. I do not believe we can fix the problem by publishing additional books or training manuals. To date, the developers in questions have not studied the books or manual available, and are unlikely to do so in the future. Short courses are a possible solution, but I believe they are too concentrated to be much use. The general concepts can be taught in a three or four day course, but that is not enough time for students to practice what they learn and acquire the experience to apply and extend the concepts to their codes. Practice is the key to becoming proficient at optimization. I recommend that graduate students be required to take a semester length course in optimization and parallel programming. We would never give someone access to state-of-the-art scientific equipment costing hundreds of thousands of dollars without first requiring them to demonstrate that they know how to use the equipment. Yet the criterion for time on state-of-the-art supercomputers is at most an interesting project. Requestors are never asked to demonstrate that they know how to use the system, or can use the system effectively. A semester course would teach them the required skills. Government agencies that fund academic scientific research pay for most of the computer systems supporting scientific research as well as the development of most personal scientific codes. These agencies should require graduate schools to offer a course in optimization and parallel programming as a requirement for funding. About the Author John Feo received his Ph.D. in Computer Science from The University of Texas at Austin in 1986. After graduate school, Dr. Feo worked at Lawrence Livermore National Laboratory where he was the Group Leader of the Computer Research Group and principal investigator of the Sisal Language Project. In 1997, Dr. Feo joined Tera Computer Company where he was project manager for the MTA, and oversaw the programming and evaluation of the MTA at the San Diego Supercomputer Center. In 2000, Dr. Feo joined Sun Microsystems as an HPC application specialist. He works with university research groups to optimize and parallelize scientific codes. Dr. Feo has published over two dozen research articles in the areas of parallel parallel programming, parallel programming languages, and application performance.

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  • Categorized Document Management System

    - by cmptrgeekken
    At the company I work for, we have an intranet that provides employees with access to a wide variety of documents. These documents fall into several categories and subcategories, and each of these categories have their own web page. Below is one such page (each of the links shown will link to a similar view for that category): We currently store each document as a file on the web server and hand-code links to these documents whenever we need to add a new document. This is tedious and error-prone, and it also means we lack any sort of security for accessing these documents. I began looking into document management systems (like KnowledgeTree and OpenKM), however, none of these systems seem to provide a categorized view like in the preview above. My question is ... does anyone know of any Document Management System that allow for the type of flexibility we currently have with hand-coding links to our documents into various webpages (major and minor , while also providing security, ease of use, and (less important) version control? Or do you think I'd be better off developing such a system from scratch?

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  • Using Optical Flow in EmguCV

    - by Meko
    HI. I am trying to create simple touch game using EmguCV.Should I use optical flow to determine for interaction between images on screen and with my hand ,if changes of points somewhere on screen more than 100 where the image, it means my hand is over image? But how can I track this new points? I can draw on screen here the previous points and new points but It shows on my head more points then my hand and I can not track my hands movements. void Optical_Flow_Worker(object sender, EventArgs e) { { Input_Capture.SetCaptureProperty(Emgu.CV.CvEnum.CAP_PROP.CV_CAP_PROP_POS_FRAMES, ActualFrameNumber); ActualFrame = Input_Capture.QueryFrame(); ActualGrayFrame = ActualFrame.Convert<Gray, Byte>(); NextFrame = Input_Capture.QueryFrame(); NextGrayFrame = NextFrame.Convert<Gray, Byte>(); ActualFeature = ActualGrayFrame.GoodFeaturesToTrack(500, 0.01d, 0.01, 5); ActualGrayFrame.FindCornerSubPix(ActualFeature, new System.Drawing.Size(10, 10), new System.Drawing.Size(-1, -1), new MCvTermCriteria(20, 0.3d)); OpticalFlow.PyrLK(ActualGrayFrame, NextGrayFrame, ActualFeature[0], new System.Drawing.Size(10, 10), 3, new MCvTermCriteria(20, 0.03d), out NextFeature, out Status, out TrackError); OpticalFlowFrame = new Image<Bgr, Byte>(ActualFrame.Width, ActualFrame.Height); OpticalFlowFrame = NextFrame.Copy(); for (int i = 0; i < ActualFeature[0].Length; i++) DrawFlowVectors(i); ActualFrameNumber++; pictureBox1.Image = ActualFrame.Resize(320, 400).ToBitmap() ; pictureBox3.Image = OpticalFlowFrame.Resize(320, 400).ToBitmap(); } } private void DrawFlowVectors(int i) { System.Drawing.Point p = new Point(); System.Drawing.Point q = new Point(); p.X = (int)ActualFeature[0][i].X; p.Y = (int)ActualFeature[0][i].Y; q.X = (int)NextFeature[i].X; q.Y = (int)NextFeature[i].Y; p.X = (int)(q.X + 6 * Math.Cos(angle + Math.PI / 4)); p.Y = (int)(q.Y + 6 * Math.Sin(angle + Math.PI / 4)); p.X = (int)(q.X + 6 * Math.Cos(angle - Math.PI / 4)); p.Y = (int)(q.Y + 6 * Math.Sin(angle - Math.PI / 4)); OpticalFlowFrame.Draw(new Rectangle(q.X,q.Y,1,1), new Bgr(Color.Red), 1); OpticalFlowFrame.Draw(new Rectangle(p.X, p.Y, 1, 1), new Bgr(Color.Blue), 1); }

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  • Is it safe to delete the "ipch" folder - Precompiled headers?

    - by Jamie Keeling
    Hello, I was looking through the folder for an application I am working on and noticed the "ipch" folder, for my solution which has two small projects it weighs in at about 90mb+ in size. I have found an article discussing the use for the files and was wondering if they were safe to delete? It's for an assignment hand in and I would like to keep the electronic hand in as small as possible. If I were to delete the folder will the application remain in a safe and stable state? I apologise if this is a simple question, I have only just started using Visual Studio 2010. Thanks! Pre-Compiled Headers

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