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  • Coordinate spaces and transformation matrices

    - by Belgin
    I'm trying to get an object from object space, into projected space using these intermediate matrices: The first matrix (I) is the one that transforms from object space into inertial space, but since my object is not rotated or translated in any way inside the object space, this matrix is the 4x4 identity matrix. The second matrix (W) is the one that transforms from inertial space into world space, which is just a scale transform matrix of factor a = 14.1 on all coordinates, since the inertial space origin coincides with the world space origin. /a 0 0 0\ W = |0 a 0 0| |0 0 a 0| \0 0 0 1/ The third matrix (C) is the one that transforms from world space, into camera space. This matrix is a translation matrix with a translation of (0, 0, 10), because I want the camera to be located behind the object, so the object must be positioned 10 units into the z axis. /1 0 0 0\ C = |0 1 0 0| |0 0 1 10| \0 0 0 1/ And finally, the fourth matrix is the projection matrix (P). Bearing in mind that the eye is at the origin of the world space and the projection plane is defined by z = 1, the projection matrix is: /1 0 0 0\ P = |0 1 0 0| |0 0 1 0| \0 0 1/d 0/ where d is the distance from the eye to the projection plane, so d = 1. I'm multiplying them like this: (((P x C) x W) x I) x V, where V is the vertex' coordinates in column vector form: /x\ V = |y| |z| \1/ After I get the result, I divide x and y coordinates by w to get the actual screen coordinates. Apparenly, I'm doing something wrong or missing something completely here, because it's not rendering properly. Here's a picture of what is supposed to be the bottom side of the Stanford Dragon: Also, I should add that this is a software renderer so no DirectX or OpenGL stuff here.

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  • When does a programmer know when a new job is not right?

    - by Mysterion
    I believe that the interview process is a selling of both parties - what can the employee offer the employer and vice versa. Assuming an individual has been careful in selecting their new employer (via thorough questioning in the interview process), however when they arrive at the job they find the employer has not been honest about certain aspects of the job. Examples of this dishonesty could include: The employee making it clear that technical excellence is an important factor, which is promised by the employer, but is not fully delivered or a good technical structure does not exist. The employee states they want to work on well architected and short (lets say less than 1 yr) long projects, yet when they start they find they are placed on a poorly architected older project. The employee being told of a pair programming environment to get him up to speed on the project, but being left to his own devices/questioning on arrival. The employee is promised a culture that encourages innovation and technical excellence but finds that this is not the case (eg. using technology for knowledge retention is laughed at). I know that a lot of famous developers feel that you make the place you work at. Is it realistic for a new employee with limited experience in the industry (say less than 5 years) to be able to join the company and change attitudes or even challenge the employer on the perceived dishonesty? Should they stay in this job or cut their losses?

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  • Faster 2D Collision detection

    - by eShredder
    Recently I've been working on a fast-paced 2d shooter and I came across a mighty problem. Collision detection. Sure, it is working, but it is very slow. My goal is: Have lots of enemies on screen and have them to not touch each other. All of the enemies are chasing the player entity. Most of them have the same speed so sooner or later they all end up taking the same space while chasing the player. This really drops the fun factor since, for the player, it looks like you are being chased by one enemy only. To prevent them to take the same space I added a collision detection (a very basic 2D detection, the only method I know of) which is. Enemy class update method Loop through all enemies (continue; if the loop points at this object) If enemy object intersects with this object Push enemy object away from this enemy object This works fine. As long as I only have <200 enemy entities that is. When I get closer to 300-350 enemy entities my frame rate begins to drop heavily. First I thought it was bad rendering so I removed their draw call. This did not help at all so of course I realised it was the update method. The only heavy part in their update method is this each-enemy-loops-through-every-enemy part. When I get closer to 300 enemies the game does a 90000 (300x300) step itteration. My my~ I'm sure there must be another way to aproach this collision detection. Though I have no idea how. The pages I find is about how to actually do the collision between two objects or how to check collision between an object and a tile. I already know those two things. tl;dr? How do I aproach collision detection between LOTS of entities? Quick edit: If it is to any help, I'm using C# XNA.

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  • TraceTune supports uploading Zip files

    - by Bill Graziano
    I’ve been using the online version of ClearTrace more and more lately.  When I get to a new client it’s just much easier to upload a trace file rather than install ClearTrace. That means I’ve finally been adding more features to it.  The two latest features are around ease of use. You can now upload a ZIP file that contains a trace file.  Trace files are already somewhat compressed.  Putting it in a ZIP file further compresses it by a factor of 8X or 9X in my testing. That means you can start with a 100MB trace and end up with a 10Mb-12MB ZIP file to upload.  I’m consistently able to get over 150,000 events in a 100MB ZIP file.  That gives me a pretty good look at a system. The second part of this is that files are now processed asynchronously.  After you upload a file you’ll be taken to a processing page that updates every few seconds with the number of rows processed.  It generally takes under a minute to process a 100MB trace file but I *hated* staring at a blank screen. Give TraceTune a try.  It’s getting easier to use every day.

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  • Assuming "clean code/architecture" is there a difference in "effort" between PHP or Java/J2EE web application development?

    - by PhD
    A client asked us to estimate effort when selecting PHP as the implementation language for his next web-based application. We spent about a week exploring PHP, prototyping, testing etc., We are quite new to this language - may have hacked around it in the past but, let's go with PHP-noobs but application development experts (for the lack of a better, less flattering word :) It seems, that if we write, clean maintainable code, follow separation of concerns, enterprise architecture patters (DAOs etc.) the 'effort' in creating an object-oriented PHP based web-application seems to be the same for a Java based one. Here's our equation for estimating the effort (development/delivery time): ConstructionEffort = f(analysis, design, coding, testing, review, deployment) We were specifically comparing effort estimates in creating an enterprise application with the following: PHP + CakePHP/CodeIgniter (should we have considered others?) Java + Spring + Restlet It's an end-to-end application: Client: Javascript/jQuery + HTML/CSS Middle tier/Business Logic - (Still evaluating PHP/Java) Database: MySQL The effort estimates of the 1st and 3rd tier are constant and relatively independent of the middle tier's technology. At a high level with an initial breakdown into user stories of the requested features as well as a high-level SWAG on the sheer number of classes/SLOC that would be required for PHP doesn't seem to differ by much from what is required of the same in Java. Is this correct? We are basing our initial estimates on the initial prototyping/coding we've done with PHP - we are currently disregarding fluency with the language as a factor, since that'll be an initial hurdle and not a long term impediment IMHO (we also have sufficient time to become quite fluent with PHP). I'm interested in knowing the programmers' perspective with respect to effort when creating similar applications with either of the languages to justify choosing one over the other. Are we missing something here? It seems we are going against popular belief of PHP being quicker to market (or we being very fluent with Java have our vision clouded). It doesn't seem to have any coding/programming effort saving from what we/ve played around with.

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  • SEO and internal links

    - by hanazair
    I'm fairly new to SEO and although I've read many articles on the topic I still don't have a clear idea of how to get my client's website get to the first page of Google Search. I run MOZ competitor analysis and see that a competitor that comes up at the top of Google Search has approximately same Domain Authority, Domain Moz Rank and Trust. They have 8 External Linking Root Domains while my client's site has five. Yet the competitor comes up as one of the top sites on the first page, and my client's side is on page #3. Then I noticed one drastic difference in competitor's ranking and that is Total Links. He has 1,388! I don't understand how this could be a positive factor in Search Engine ranking and how can they legitimately have 1,388 links (while only 14 of those are external). Another competitor who is #2 in search engine rankings has 773 links total with only 14 external links. It seems fishy, but yet there they are - at the top of the search engine results. Is that some current way to trick Search Engines? What to do if I'd like to get my client's website onto the first page by some legitimate means? Thanks.

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  • Why isn't my other two constant buffers being updated to the shader?

    - by Paul Ske
    I posted previously before about my two dynamic buffers not being dynamically updating the constant shader. The tessellation buffer isn't working because I have to manually update the tessellation factor inside the hull shader. I believe the camera position isn't updating either because when I perform distance adaptation the far edges are more tessellated then the what's truly in front of the camera. I have all the buffers set to dynamic. Inside the render loop I have them set as: ID3D11Buffer *multiBuffers[3]; devcon->VSSetConstantBuffers(0,3,multiBuffers); ... devcon->DSSetConstantBuffers(0,3,multiBuffers); I only got that from a directX Sample. Inside the shader file I have the three cbuffer structs. cbuffer ConstantBuffer { float4x4 WorldMatrix; float4x4 viewMatrix; float4x4 projectionMatrix; float4x4 modelWorldMatrix; // the rotation matrix float3 lightvec; // the light's vector float4 lightcol; // the light's color float4 ambientcol; // the ambient light's color bool isSelected; } cbuffer cameraBuffer { float3 cameraDirection; float padding; } cbuffer TessellationBuffer { float tessellationAmount; float3 padding2; } Am I missing something or would anyone know why wouldn't my buffers update to the shader file?

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  • Rendering a DOM across multiple displays

    - by meetamit
    I'm building a data-driven animation with HTML and javascript to run in a web browser. I would like to display it tiled across three 1080p monitors. This essentially yields a viewport that's 5760px wide and 1080px tall. Pretty large. Does anyone have experience setting up something like this? I have many questions below, but any tip would be appreciated: Is it reasonable to expect a DOM to render into such a large viewport size at close to 60fps? I might choose to use canvas, instead of SVG or HTML, but that would yield a giant canvas. Can a canvas with such high resolution be performant? Of course everything depends on the complexity of the graphics I want to render, but I'm looking to remove that factor from this question, so assume I'm asking about a canvas animation that can run at 60fps at 1920x1080 resolution. Would it run roughly as fast at 3 times the width? Would three.js and WebGL be a more proper approach at that resolution? How do you actually cause Chrome or FF to span 3 monitors at full screen? Do I need a 3rd party solution of any kind? Thanks!

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  • How can I make this arcade-highscore game more fun/interesting?

    - by j-a
    I'm having difficulties getting the fun factor into this iPhone game, and I am looking for some ideas or advice. I was asked to generalize the question a bit. What are some techniques for arcade highscore games that can be applied to this game in order to: Make each second of the game fun and challenging, from the first second to the end of the game. Regardless of skill level. Make the player want to try again and again to beat the high score. Briefly about the game: you aim using your finger and pull the bow chord and release by lifting your finger. That part feels quite nice how the bow interacts with the finger. The game idea: hearts fall down and you get 1 pt for each heart you shoot. You start with a few arrows and every now and then a bag of arrow comes down which - if you hit it, you get more arrows. Once your out of arrows the game is over. So it is all about beating your previous high score or your friends high scores. Unfortunately I don't find it that fun. Thankful for any ideas/suggestions/thoughts on how to make it more fun/interesting.

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  • Summary of usage policies for website integration of various social media networks?

    - by Dallas
    To cut to the chase... I look at Twitter's usage policy and see limitations on what can and can't be done with their logo. I also see examples of websites that use icons that have been integrated with the look and feel of their own site. Given Twitter's policy, for example, it would appear that legal conversations/agreements would need to take place to do this, especially on a commercial site. I believe it is perfectly acceptable to have a plain text button that simply has the word "Tweet" on it, that has the same functionality. My question is if anyone can provide online (or other) references that attempt to summarize what can and can't be done when integrating various social networks into your own work? The answer I will mark as the correct one will be the one which provides the best resource(s) giving the best summaries of what can and can't be done with specific logos/icons, with a secondary factor being that a variety of social networking sites are addressed in your answer. Before people point to specific questions, I am looking for a well-rounded approach that considers a breadth of networks and considerations. Background: I would like to incorporate social media icons and functionality, but would like to consider what type of modifications can be done without needing to involve lawyers. For example, can I bring in a standard Facebook logo, but incorporate my site color into the logo? Would the answer differ if I maintained their color, but add in a few pixels of another color to transition? I am not saying I want to do this, but rather using it as an example.

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  • Project Showcase: SaaS Web Apps Hits a Home Run with New SCMS Database

    - by Webgui
    We love seeing projects from start to finish, and we’re happy to share the latest example with you. Who: SaaS Web Apps – they use Software as a Service to create web applications that look and feel like desktop applications. What: SaaS Web Apps needed to build a Sports Contract Management System (SCMS) for one of its customers, Premier Stinson Sports. Why: The SCMS database is used for collecting, analyzing and recording college coach and athletic directors’ employment and contract data. The Challenge: Premier Stinson Sports works with a number of partners, each with its own needs and unique requirements. For example, USA Today uses the system to provide cutting edge news analysis while The National Sports Law Institute of Marquette University Law School uses it to for the latest sports contract data and student analysis. In addition, the system needed to be secure due to the sensitivity of the data; it was essential that the user security and permissions be easily configurable. As always, performance was a key factor, especially with the intense reporting and analytical capabilities for this project. Because of this, most of the processing had to be done on a dedicated server but the project called for the richness and responsiveness of a desktop application. The Solution: To execute the project, SaaS Web Apps used APS.Net-based Visual WebGui from Gizmox, combined with SQL Server 2008 and SQL Reporting Services. This combination resulted in a quick deployment for SaaS Web Apps’ customers. The Result: The completed project gave each partner the scalability and availability of a web application with the performance and security of a desktop application. As an example, USA Today pulls data from this database to give readers the latest sports stats – Salary analysis of 2010 Football Bowl Subdivision Coaches. And here’s a screenshot of the database itself. Great work, SaaS Web Apps!

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  • What is a good way to refactor a large, terribly written code base by myself? [closed]

    - by AgentKC
    Possible Duplicate: Techniques to re-factor garbage and maintain sanity? I have a fairly large PHP code base that I have been writing for the past 3 years. The problem is, I wrote this code when I was a terrible programmer and now it's tens of thousands of lines of conditionals and random MySQL queries everywhere. As you can imagine, there are a ton of bugs and they are extremely hard to find and fix. So I would like a good method to refactor this code so that it is much more manageable. The source code is quite bad; I did not even use classes or functions when I originally wrote it. At this point, I am considering rewriting the whole thing. I am the only developer and my time is pretty limited. I would like to get this done as quickly as possible, so I can get back to writing new features. Since rewriting the code would take a long time, I am looking for some methods that I can use to clean up the code as quickly as possible without leaving more bad architecture that will come back to haunt me later. So this is the basic question: What is a good way for a single developer to take a fairly large code base that has no architecture and refactor it into something with reasonable architecture that is not a nightmare to maintain and expand?

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  • ADF - Now with Robots!

    - by Duncan Mills
    I mentioned this briefly in a tweet the other day, just before the full rush of OOW really kicked off, so I though it was worth re-visiting. Check out this video, and then read on: So why so interesting? Well - you probably guessed from the title, ADF is involved. Indeed this is as about as far from the traditional ADF data entry application as you can get. Instead of a database at the back-end there's basically a robot. That's right, this remarkable tape drive is controlled through an ADF using all your usual friends of ADF Faces, Controller and Binding (but no ADFBC for obvious reasons). ADF is used both on the touch screen you see on the front of the device in the video, and also for the remote management console which provides a visual representation of the slots and drives. The latter uses ADF's Active Data Framework to provide a real-time view of what's going on the rack. . What's even more interesting (for the techno-geeks) is the fact that all of this is running out of flash storage on a ridiculously small form factor with tiny processor - I probably shouldn't reveal the actual specs but take my word for it, don't complain about the capabilities of your laptop ever again! This is a project that I've been personally involved in and I'm pumped to see such a good result and,  I have to say, those hardware guys are great to work with (and have way better toys on their desks than we do). More info in the SL150 (should you feel the urge to own one) is here. 

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  • Working with volonteers

    - by JavaCecilia
    I've been engaged as a scout leader in the Scout movement since 1993, working on a local and national level, leading both kids and other scout leaders.Last year, the Swedish Scout Association invited 40000 scouts aged 14-17 years old from 150 countries around the world to go camping for 10 days. I was on the planning team with a couple of hundreds of my closest scout friends and during a couple of years we spent our spare time planning logistics, food, program, etc to give these youths an experience of a life time. It was a big and complex project; different languages, religion (Ramadan was celebrated during the camp) and the Swedish weather were some of the factors we had to take into account. The camp was a huge success, the daily wow factor was measured and people truly had fun and got to know each other. I learnt a lot and got friends around the globe - looking back at the pictures it feels unreal that we managed it.The Java platform as OpenJDK and its' future is a similar project in my mind. With 9 million developers and being installed on 3 bn devices, the platform touches a lot of users and businesses. There's a strong community taking Java into the future, making sure it stays relevant. Finding ways to collaborate in a scalable way is the key to success here. We have the bylaws directing how decisions are made, roles are appointed and how to "level" within the community. Using these, we can then make contributions according to our competence and interest and innovate taking our platform into the future.If you find a way to organize volunteers towards a common goal, solving conflicts, making decisions, dividing the work into manageable chunks and having fun while doing it - there's no end to what you can achieve.

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  • Seek first to understand, then to be understood

    - by BuckWoody
    One of the most important (and most difficult) lessons for a technical professional to learn is to not jump to the solution. Perhaps you’ve done this, or had it happen to you. As the person you’re “listening” to is speaking, your mind is performing a B-Tree lookup on possible solutions, and when the final node of the B-Tree in your mind is reached, you blurt out the “only” solution there is to the problem, whether they are done or not. There are two issues here – both of them fatal if you don’t factor them in. First, your B-Tree may not be complete, or correct. That of course leads to an incorrect response, which blows your credibility. People will not trust you if this happens often. The second danger is that the person may modify their entire problem with a single word or phrase. I once had a client explain a detailed problem to me – and I just KNEW the answer. Then they said at the end “well, that’s what it used to do, anyway. Now it doesn’t do that anymore.” Which of course negated my entire solution – happily I had kept my mouth shut until they finished. So practice listening, rather than waiting for your turn to speak. Let the person finish, let them get the concept out, give them your full attention. They’ll appreciate the courtesy, you’ll look more intelligent, and you both may find the right answer to the problem. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Best practice- handling images on website

    - by Steve
    I am porting an old eCommerce site to MVC 3 and would like to take advantage of design improvements. The site currently has product images stored in 3 sizes: thumbnail, medium (for display in a list) and expanded for a zoomed look. Right now we are having to upload 3 separate images that are sized exactly right, provide 3 different names that match what the site expects, etc., it is a pain. I'd like to upload just 1 file, the large one, then let the site reduce it to needed sizes, and I'd like the flexibility to change the thumbnail and list sizes depending on user preferences, form factor (e.g. mobile, iPad, desktop), etc. so might need many copies of the same image. My question is should the image be reduced then saved several times upon upload and if so what is a good storage/naming convention? The other idea is to store just the single image but resize it programmatically before serving it to the client. Has anybody done this and what are the tradeoffs besides a few more machine cycles? How do you pass a temporary image in memory to the client (there is no URL)?

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  • The best programmer is N times more effective than the worst? Who Cares?

    - by StevenWilkins
    There is a latent belief in programming that the best programmer is N times more effective than the worst. Where N is usually between 10 and 100. Here are some examples: http://www.devtopics.com/programmer-productivity-the-tenfinity-factor/ http://www.joelonsoftware.com/articles/HighNotes.html http://haacked.com/archive/2007/06/25/understanding-productivity-differences-between-developers.aspx There is some debate as to whether or not it's been proven: http://morendil.github.com/folklore.html I'm confident in the accuracy of these statements: The best salesmen in the world are probably 10-100 times better than the worst The best drivers in the world are probably 10-100 times better than the worst The best soccer players in the world are probably 10-100 times better than the worst The best CEOs in the world are probably 10-100 times better than the worst In some cases, I'm sure the difference is greater. In fact, you could probably say that The best [insert any skilled profession here] in the world are probably 10-100 times better than the worst We don't know what N is for the rest of these professions, so why concern ourselves with what the actual number is for programming? Can we not just say that the number is large enough so that it's very important to hire the best people and move on already?

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  • What are the design principles that promote testable code? (designing testable code vs driving design through tests)

    - by bot
    Most of the projects that I work on consider development and unit testing in isolation which makes writing unit tests at a later instance a nightmare. My objective is to keep testing in mind during the high level and low level design phases itself. I want to know if there are any well defined design principles that promote testable code. One such principle that I have come to understand recently is Dependency Inversion through Dependency injection and Inversion of Control. I have read that there is something known as SOLID. I want to understand if following the SOLID principles indirectly results in code that is easily testable? If not, are there any well-defined design principles that promote testable code? I am aware that there is something known as Test Driven Development. Although, I am more interested in designing code with testing in mind during the design phase itself rather than driving design through tests. I hope this makes sense. One more question related to this topic is whether it's alright to re-factor an existing product/project and make changes to code and design for the purpose of being able to write a unit test case for each module?

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  • Store scores for players and produce a high score list

    - by zrvan
    This question is derived from an interview question that I got for a job I was declined. I have asked for code review for my solution at the dedicated Stack Exchange site. But I hope this question is sufficiently rephrased and asked with a different motivation not to be a duplicate of the other question. Consider the following scenario: You should store player scores in the server back end of a game. The server is written in Java. Every score should be registered, that is, one player may have any number of scores for any number of levels. A high score list should be produced with the fifteen top scores for a given level, but only one score per user (to the effect that even if player X has the two highest scores for level Y, only the first position is counted and player Z has the second place). No information should be persisted and only Java 1.7+ standard libraries should be used. No third party libraries or frameworks are acceptable. With the number of players as the primary factor, what would be the best data structure in terms of scalability and concurrency? How would you access the structure to register a single score given a level and a player id? How would you access the structure to compile the high score list?

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  • Parallelize code using CUDA [migrated]

    - by user878944
    If I have a code which takes struct variable as input and manipulate it's elements, how can I parallelize this using CUDA? void BackpropagateLayer(NET* Net, LAYER* Upper, LAYER* Lower) { INT i,j; REAL Out, Err; for (i=1; i<=Lower->Units; i++) { Out = Lower->Output[i]; Err = 0; for (j=1; j<=Upper->Units; j++) { Err += Upper->Weight[j][i] * Upper->Error[j]; } Lower->Error[i] = Net->Gain * Out * (1-Out) * Err; } } Where NET and LAYER are structs defined as: typedef struct { /* A LAYER OF A NET: */ INT Units; /* - number of units in this layer */ REAL* Output; /* - output of ith unit */ REAL* Error; /* - error term of ith unit */ REAL** Weight; /* - connection weights to ith unit */ REAL** WeightSave; /* - saved weights for stopped training */ REAL** dWeight; /* - last weight deltas for momentum */ } LAYER; typedef struct { /* A NET: */ LAYER** Layer; /* - layers of this net */ LAYER* InputLayer; /* - input layer */ LAYER* OutputLayer; /* - output layer */ REAL Alpha; /* - momentum factor */ REAL Eta; /* - learning rate */ REAL Gain; /* - gain of sigmoid function */ REAL Error; /* - total net error */ } NET; What I could think of is to first convert the 2d Weight into 1d. And then send it to kernel to take the product or just use the CUBLAS library. Any suggestions?

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  • eBooks on iPad vs. Kindle: More Debate than Smackdown

    - by andrewbrust
    When the iPad was presented at its San Francisco launch event on January 28th, Steve Jobs spent a significant amount of time explaining how well the device would serve as an eBook reader. He showed the iBooks reader application and iBookstore and laid down the gauntlet before Amazon and its beloved Kindle device. Almost immediately afterwards, criticism came rushing forth that the iPad could never beat the Kindle for book reading. The curious part of that criticism is that virtually no one offering it had actually used the iPad yet. A few weeks later, on April 3rd, the iPad was released for sale in the United States. I bought one on that day and in the few additional weeks that have elapsed, I’ve given quite a workout to most of its capabilities, including its eBook features. I’ve also spent some time with the Kindle, albeit a first-generation model, to see how it actually compares to the iPad. I had some expectations going in, but I came away with conclusions about each device that were more scenario-based than absolute. I present my findings to you here.   Vital Statistics Let’s start with an inventory of each device’s underlying technology. The iPad has a color, backlit LCD screen and an on-screen keyboard. It has a battery which, on a full charge, lasts anywhere from 6-10 hours. The Kindle offers a monochrome, reflective E Ink display, a physical keyboard and a battery that on my first gen loaner unit can go up to a week between charges (Amazon claims the battery on the Kindle 2 can last up to 2 weeks on a single charge). The Kindle connects to Amazon’s Kindle Store using a 3G modem (the technology and network vary depending on the model) that incurs no airtime service charges whatsoever. The iPad units that are on-sale today work over WiFi only. 3G-equipped models will be on sale shortly and will command a $130 premium over their WiFi-only counterparts. 3G service on the iPad, in the U.S. from AT&T, will be fee-based, with a 250MB plan at $14.99 per month and an unlimited plan at $29.99. No contract is required for 3G service. All these tech specs aside, I think a more useful observation is that the iPad is a multi-purpose Internet-connected entertainment device, while the Kindle is a dedicated reading device. The question is whether those differences in design and intended use create a clear-cut winner for reading electronic publications. Let’s take a look at each device, in isolation, now.   Kindle To me, what’s most innovative about the Kindle is its E Ink display. E Ink really looks like ink on a sheet of paper. It requires no backlight, it’s fully visible in direct sunlight and it causes almost none of the eyestrain that LCD-based computer display technology (like that used on the iPad) does. It’s really versatile in an all-around way. Forgive me if this sounds precious, but reading on it is really a joy. In fact, it’s a genuinely relaxing experience. Through the Kindle Store, Amazon allows users to download books (including audio books), magazines, newspapers and blog feeds. Books and magazines can be purchased either on a single-issue basis or as an annual subscription. Books, of course, are purchased singly. Oddly, blogs are not free, but instead carry a monthly subscription fee, typically $1.99. To me this is ludicrous, but I suppose the free 3G service is partially to blame. Books and magazine issues download quickly. Magazine and blog subscriptions cause new issues or posts to be pushed to your device on an automated basis. Available blogs include 9000-odd feeds that Amazon offers on the Kindle Store; unless I missed something, arbitrary RSS feeds are not supported (though there are third party workarounds to this limitation). The shopping experience is integrated well, has an huge selection, and offers certain graphical perks. For example, magazine and newspaper logos are displayed in menus, and book cover thumbnails appear as well. A simple search mechanism is provided and text entry through the physical keyboard is relatively painless. It’s very easy and straightforward to enter the store, find something you like and start reading it quickly. If you know what you’re looking for, it’s even faster. Given Kindle’s high portability, very reliable battery, instant-on capability and highly integrated content acquisition, it makes reading on whim, and in random spurts of downtime, very attractive. The Kindle’s home screen lists all of your publications, and easily lets you select one, then start reading it. Once opened, publications display in crisp, attractive text that is adjustable in size. “Turning” pages is achieved through buttons dedicated to the task. Notes can be recorded, bookmarks can be saved and pages can be saved as clippings. I am not an avid book reader, and yet I found the Kindle made it really fun, convenient and soothing to read. There’s something about the easy access to the material and the simplicity of the display that makes the Kindle seduce you into chilling out and reading page after page. On the other hand, the Kindle has an awkward navigation interface. While menus are displayed clearly on the screen, the method of selecting menu items is tricky: alongside the right-hand edge of the main display is a thin column that acts as a second display. It has a white background, and a scrollable silver cursor that is moved up or down through the use of the device’s scrollwheel. Picking a menu item on the main display involves scrolling the silver cursor to a position parallel to that menu item and pushing the scrollwheel in. This navigation technique creates a disconnect, literally. You don’t really click on a selection so much as you gesture toward it. I got used to this technique quickly, but I didn’t love it. It definitely created a kind of anxiety in me, making me feel the need to speed through menus and get to my destination document quickly. Once there, I could calm down and relax. Books are great on the Kindle. Magazines and newspapers much less so. I found the rendering of photographs, and even illustrations, to be unacceptably crude. For this reason, I expect that reading textbooks on the Kindle may leave students wanting. I found that the original flow and layout of any publication was sacrificed on the Kindle. In effect, browsing a magazine or newspaper was almost impossible. Reading the text of individual articles was enjoyable, but having to read this way made the whole experience much more “a la carte” than cohesive and thematic between articles. I imagine that for academic journals this is ideal, but for consumer publications it imposes a stripped-down, low-fidelity experience that evokes a sense of deprivation. In general, the Kindle is great for reading text. For just about anything else, especially activity that involves exploratory browsing, meandering and short-attention-span reading, it presents a real barrier to entry and adoption. Avid book readers will enjoy the Kindle (if they’re not already). It’s a great device for losing oneself in a book over long sittings. Multitaskers who are more interested in periodicals, be they online or off, will like it much less, as they will find compromise, and even sacrifice, to be palpable.   iPad The iPad is a very different device from the Kindle. While the Kindle is oriented to pages of text, the iPad orbits around applications and their interfaces. Be it the pinch and zoom experience in the browser, the rich media features that augment content on news and weather sites, or the ability to interact with social networking services like Twitter, the iPad is versatile. While it shares a slate-like form factor with the Kindle, it’s effectively an elegant personal computer. One of its many features is the iBook application and integration of the iBookstore. But it’s a multi-purpose device. That turns out to be good and bad, depending on what you’re reading. The iBookstore is great for browsing. It’s color, rich animation-laden user interface make it possible to shop for books, rather than merely search and acquire them. Unfortunately, its selection is rather sparse at the moment. If you’re looking for a New York Times bestseller, or other popular titles, you should be OK. If you want to read something more specialized, it’s much harder. Unlike the awkward navigation interface of the Kindle, the iPad offers a nearly flawless touch-screen interface that seduces the user into tinkering and kibitzing every bit as much as the Kindle lulls you into a deep, concentrated read. It’s a dynamic and interactive device, whereas the Kindle is static and passive. The iBook reader is slick and fun. Use the iPad in landscape mode and you can read the book in 2-up (left/right 2-page) display; use it in portrait mode and you can read one page at a time. Rather than clicking a hardware button to turn pages, you simply drag and wipe from right-to-left to flip the single or right-hand page. The page actually travels through an animated path as it would in a physical book. The intuitiveness of the interface is uncanny. The reader also accommodates saving of bookmarks, searching of the text, and the ability to highlight a word and look it up in a dictionary. Pages display brightly and clearly. They’re easy to read. But the backlight and the glare made me less comfortable than I was with the Kindle. The knowledge that completely different applications (including the Web and email and Twitter) were just a few taps away made me antsy and very tempted to task-switch. The knowledge that battery life is an issue created subtle discomfort. If the Kindle makes you feel like you’re in a library reading room, then the iPad makes you feel, at best, like you’re under fluorescent lights at a Barnes and Noble or Borders store. If you’re lucky, you’d be on a couch or at a reading table in the store, but you might also be standing up, in the aisles. Clearly, I didn’t find this conducive to focused and sustained reading. But that may have more to do with my own tendency to read periodicals far more than books, and my neurotic . And, truth be known, the book reading experience, when not explicitly compared to Kindle’s, was still pleasant. It is also important to point out that Kindle Store-sourced books can be read on the iPad through a Kindle reader application, from Amazon, specific to the device. This offered a less rich experience than the iBooks reader, but it was completely adequate. Despite the Kindle brand of the reader, however, it offered little in terms of simulating the reading experience on its namesake device. When it comes to periodicals, the iPad wins hands down. Magazines, even if merely scanned images of their print editions, read on the iPad in a way that felt similar to reading hard copy. The full color display, touch navigation and even the ability to render advertisements in their full glory makes the iPad a great way to read through any piece of work that is measured in pages, rather than chapters. There are many ways to get magazines and newspapers onto the iPad, including the Zinio reader, and publication-specific applications like the Wall Street Journal’s and Popular Science’s. The New York Times’ free Editors’ Choice application offers a Times Reader-like interface to a subset of the Gray Lady’s daily content. The completely Web-based but iPad-optimized Times Skimmer site (at www.nytimes.com/timesskimmer) works well too. Even conventional Web sites themselves can be read much like magazines, given the iPad’s ability to zoom in on the text and crop out advertisements on the margins. While the Kindle does have an experimental Web browser, it reminded me a lot of early mobile phone browsers, only in a larger size. For text-heavy sites with simple layout, it works fine. For just about anything else, it becomes more trouble than it’s worth. And given the way magazine articles make me think of things I want to look up online, I think that’s a real liability for the Kindle.   Summing Up What I came to realize is that the Kindle isn’t so much a computer or even an Internet device as it is a printer. While it doesn’t use physical paper, it still renders its content a page at a time, just like a laser printer does, and its output appears strikingly similar. You can read the rendered text, but you can’t interact with it in any way. That’s why the navigation requires a separate cursor display area. And because of the page-oriented rendering behavior, turning pages causes a flash on the display and requires a sometimes long pause before the next page is rendered. The good side of this is that once the page is generated, no battery power is required to display it. That makes for great battery life, optimal viewing under most lighting conditions (as long as there is some light) and low-eyestrain text-centric display of content. The Kindle is highly portable, has an excellent selection in its store and is refreshingly distraction-free. All of this is ideal for reading books. And iPad doesn’t offer any of it. What iPad does offer is versatility, variety, richness and luxury. It’s flush with accoutrements even if it’s low on focused, sustained text display. That makes it inferior to the Kindle for book reading. But that also makes it better than the Kindle for almost everything else. As such, and given that its book reading experience is still decent (even if not superior), I think the iPad will give Kindle a run for its money. True book lovers, and people on a budget, will want the Kindle. People with a robust amount of discretionary income may want both devices. Everyone else who is interested in a slate form factor e-reading device, especially if they also wish to have leisure-friendly Internet access, will likely choose the iPad exclusively. One thing is for sure: iPad has reduced Kindle’s market, and may have shifted its mass market potential to a mere niche play. If Amazon is smart, it will improve its iPad-based Kindle reader app significantly. It can then leverage the iPad channel as a significant market for the Kindle Store. After all, selling the eBooks themselves is what Amazon should care most about.

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  • Currency Conversion in Oracle BI applications

    - by Saurabh Verma
    Authored by Vijay Aggarwal and Hichem Sellami A typical data warehouse contains Star and/or Snowflake schema, made up of Dimensions and Facts. The facts store various numerical information including amounts. Example; Order Amount, Invoice Amount etc. With the true global nature of business now-a-days, the end-users want to view the reports in their own currency or in global/common currency as defined by their business. This presents a unique opportunity in BI to provide the amounts in converted rates either by pre-storing or by doing on-the-fly conversions while displaying the reports to the users. Source Systems OBIA caters to various source systems like EBS, PSFT, Sebl, JDE, Fusion etc. Each source has its own unique and intricate ways of defining and storing currency data, doing currency conversions and presenting to the OLTP users. For example; EBS stores conversion rates between currencies which can be classified by conversion rates, like Corporate rate, Spot rate, Period rate etc. Siebel stores exchange rates by conversion rates like Daily. EBS/Fusion stores the conversion rates for each day, where as PSFT/Siebel store for a range of days. PSFT has Rate Multiplication Factor and Rate Division Factor and we need to calculate the Rate based on them, where as other Source systems store the Currency Exchange Rate directly. OBIA Design The data consolidation from various disparate source systems, poses the challenge to conform various currencies, rate types, exchange rates etc., and designing the best way to present the amounts to the users without affecting the performance. When consolidating the data for reporting in OBIA, we have designed the mechanisms in the Common Dimension, to allow users to report based on their required currencies. OBIA Facts store amounts in various currencies: Document Currency: This is the currency of the actual transaction. For a multinational company, this can be in various currencies. Local Currency: This is the base currency in which the accounting entries are recorded by the business. This is generally defined in the Ledger of the company. Global Currencies: OBIA provides five Global Currencies. Three are used across all modules. The last two are for CRM only. A Global currency is very useful when creating reports where the data is viewed enterprise-wide. Example; a US based multinational would want to see the reports in USD. The company will choose USD as one of the global currencies. OBIA allows users to define up-to five global currencies during the initial implementation. The term Currency Preference is used to designate the set of values: Document Currency, Local Currency, Global Currency 1, Global Currency 2, Global Currency 3; which are shared among all modules. There are four more currency preferences, specific to certain modules: Global Currency 4 (aka CRM Currency) and Global Currency 5 which are used in CRM; and Project Currency and Contract Currency, used in Project Analytics. When choosing Local Currency for Currency preference, the data will show in the currency of the Ledger (or Business Unit) in the prompt. So it is important to select one Ledger or Business Unit when viewing data in Local Currency. More on this can be found in the section: Toggling Currency Preferences in the Dashboard. Design Logic When extracting the fact data, the OOTB mappings extract and load the document amount, and the local amount in target tables. It also loads the exchange rates required to convert the document amount into the corresponding global amounts. If the source system only provides the document amount in the transaction, the extract mapping does a lookup to get the Local currency code, and the Local exchange rate. The Load mapping then uses the local currency code and rate to derive the local amount. The load mapping also fetches the Global Currencies and looks up the corresponding exchange rates. The lookup of exchange rates is done via the Exchange Rate Dimension provided as a Common/Conforming Dimension in OBIA. The Exchange Rate Dimension stores the exchange rates between various currencies for a date range and Rate Type. Two physical tables W_EXCH_RATE_G and W_GLOBAL_EXCH_RATE_G are used to provide the lookups and conversions between currencies. The data is loaded from the source system’s Ledger tables. W_EXCH_RATE_G stores the exchange rates between currencies with a date range. On the other hand, W_GLOBAL_EXCH_RATE_G stores the currency conversions between the document currency and the pre-defined five Global Currencies for each day. Based on the requirements, the fact mappings can decide and use one or both tables to do the conversion. Currency design in OBIA also taps into the MLS and Domain architecture, thus allowing the users to map the currencies to a universal Domain during the implementation time. This is especially important for companies deploying and using OBIA with multiple source adapters. Some Gotchas to Look for It is necessary to think through the currencies during the initial implementation. 1) Identify various types of currencies that are used by your business. Understand what will be your Local (or Base) and Documentation currency. Identify various global currencies that your users will want to look at the reports. This will be based on the global nature of your business. Changes to these currencies later in the project, while permitted, but may cause Full data loads and hence lost time. 2) If the user has a multi source system make sure that the Global Currencies and Global Rate Types chosen in Configuration Manager do have the corresponding source specific counterparts. In other words, make sure for every DW specific value chosen for Currency Code or Rate Type, there is a source Domain mapping already done. Technical Section This section will briefly mention the technical scenarios employed in the OBIA adaptors to extract data from each source system. In OBIA, we have two main tables which store the Currency Rate information as explained in previous sections. W_EXCH_RATE_G and W_GLOBAL_EXCH_RATE_G are the two tables. W_EXCH_RATE_G stores all the Currency Conversions present in the source system. It captures data for a Date Range. W_GLOBAL_EXCH_RATE_G has Global Currency Conversions stored at a Daily level. However the challenge here is to store all the 5 Global Currency Exchange Rates in a single record for each From Currency. Let’s voyage further into the Source System Extraction logic for each of these tables and understand the flow briefly. EBS: In EBS, we have Currency Data stored in GL_DAILY_RATES table. As the name indicates GL_DAILY_RATES EBS table has data at a daily level. However in our warehouse we store the data with a Date Range and insert a new range record only when the Exchange Rate changes for a particular From Currency, To Currency and Rate Type. Below are the main logical steps that we employ in this process. (Incremental Flow only) – Cleanup the data in W_EXCH_RATE_G. Delete the records which have Start Date > minimum conversion date Update the End Date of the existing records. Compress the daily data from GL_DAILY_RATES table into Range Records. Incremental map uses $$XRATE_UPD_NUM_DAY as an extra parameter. Generate Previous Rate, Previous Date and Next Date for each of the Daily record from the OLTP. Filter out the records which have Conversion Rate same as Previous Rates or if the Conversion Date lies within a single day range. Mark the records as ‘Keep’ and ‘Filter’ and also get the final End Date for the single Range record (Unique Combination of From Date, To Date, Rate and Conversion Date). Filter the records marked as ‘Filter’ in the INFA map. The above steps will load W_EXCH_RATE_GS. Step 0 updates/deletes W_EXCH_RATE_G directly. SIL map will then insert/update the GS data into W_EXCH_RATE_G. These steps convert the daily records in GL_DAILY_RATES to Range records in W_EXCH_RATE_G. We do not need such special logic for loading W_GLOBAL_EXCH_RATE_G. This is a table where we store data at a Daily Granular Level. However we need to pivot the data because the data present in multiple rows in source tables needs to be stored in different columns of the same row in DW. We use GROUP BY and CASE logic to achieve this. Fusion: Fusion has extraction logic very similar to EBS. The only difference is that the Cleanup logic that was mentioned in step 0 above does not use $$XRATE_UPD_NUM_DAY parameter. In Fusion we bring all the Exchange Rates in Incremental as well and do the cleanup. The SIL then takes care of Insert/Updates accordingly. PeopleSoft:PeopleSoft does not have From Date and To Date explicitly in the Source tables. Let’s look at an example. Please note that this is achieved from PS1 onwards only. 1 Jan 2010 – USD to INR – 45 31 Jan 2010 – USD to INR – 46 PSFT stores records in above fashion. This means that Exchange Rate of 45 for USD to INR is applicable for 1 Jan 2010 to 30 Jan 2010. We need to store data in this fashion in DW. Also PSFT has Exchange Rate stored as RATE_MULT and RATE_DIV. We need to do a RATE_MULT/RATE_DIV to get the correct Exchange Rate. We generate From Date and To Date while extracting data from source and this has certain assumptions: If a record gets updated/inserted in the source, it will be extracted in incremental. Also if this updated/inserted record is between other dates, then we also extract the preceding and succeeding records (based on dates) of this record. This is required because we need to generate a range record and we have 3 records whose ranges have changed. Taking the same example as above, if there is a new record which gets inserted on 15 Jan 2010; the new ranges are 1 Jan to 14 Jan, 15 Jan to 30 Jan and 31 Jan to Next available date. Even though 1 Jan record and 31 Jan have not changed, we will still extract them because the range is affected. Similar logic is used for Global Exchange Rate Extraction. We create the Range records and get it into a Temporary table. Then we join to Day Dimension, create individual records and pivot the data to get the 5 Global Exchange Rates for each From Currency, Date and Rate Type. Siebel: Siebel Facts are dependent on Global Exchange Rates heavily and almost none of them really use individual Exchange Rates. In other words, W_GLOBAL_EXCH_RATE_G is the main table used in Siebel from PS1 release onwards. As of January 2002, the Euro Triangulation method for converting between currencies belonging to EMU members is not needed for present and future currency exchanges. However, the method is still available in Siebel applications, as are the old currencies, so that historical data can be maintained accurately. The following description applies only to historical data needing conversion prior to the 2002 switch to the Euro for the EMU member countries. If a country is a member of the European Monetary Union (EMU), you should convert its currency to other currencies through the Euro. This is called triangulation, and it is used whenever either currency being converted has EMU Triangulation checked. Due to this, there are multiple extraction flows in SEBL ie. EUR to EMU, EUR to NonEMU, EUR to DMC and so on. We load W_EXCH_RATE_G through multiple flows with these data. This has been kept same as previous versions of OBIA. W_GLOBAL_EXCH_RATE_G being a new table does not have such needs. However SEBL does not have From Date and To Date columns in the Source tables similar to PSFT. We use similar extraction logic as explained in PSFT section for SEBL as well. What if all 5 Global Currencies configured are same? As mentioned in previous sections, from PS1 onwards we store Global Exchange Rates in W_GLOBAL_EXCH_RATE_G table. The extraction logic for this table involves Pivoting data from multiple rows into a single row with 5 Global Exchange Rates in 5 columns. As mentioned in previous sections, we use CASE and GROUP BY functions to achieve this. This approach poses a unique problem when all the 5 Global Currencies Chosen are same. For example – If the user configures all 5 Global Currencies as ‘USD’ then the extract logic will not be able to generate a record for From Currency=USD. This is because, not all Source Systems will have a USD->USD conversion record. We have _Generated mappings to take care of this case. We generate a record with Conversion Rate=1 for such cases. Reusable Lookups Before PS1, we had a Mapplet for Currency Conversions. In PS1, we only have reusable Lookups- LKP_W_EXCH_RATE_G and LKP_W_GLOBAL_EXCH_RATE_G. These lookups have another layer of logic so that all the lookup conditions are met when they are used in various Fact Mappings. Any user who would want to do a LKP on W_EXCH_RATE_G or W_GLOBAL_EXCH_RATE_G should and must use these Lookups. A direct join or Lookup on the tables might lead to wrong data being returned. Changing Currency preferences in the Dashboard: In the 796x series, all amount metrics in OBIA were showing the Global1 amount. The customer needed to change the metric definitions to show them in another Currency preference. Project Analytics started supporting currency preferences since 7.9.6 release though, and it published a Tech note for other module customers to add toggling between currency preferences to the solution. List of Currency Preferences Starting from 11.1.1.x release, the BI Platform added a new feature to support multiple currencies. The new session variable (PREFERRED_CURRENCY) is populated through a newly introduced currency prompt. This prompt can take its values from the xml file: userpref_currencies_OBIA.xml, which is hosted in the BI Server installation folder, under :< home>\instances\instance1\config\OracleBIPresentationServicesComponent\coreapplication_obips1\userpref_currencies.xml This file contains the list of currency preferences, like“Local Currency”, “Global Currency 1”,…which customers can also rename to give them more meaningful business names. There are two options for showing the list of currency preferences to the user in the dashboard: Static and Dynamic. In Static mode, all users will see the full list as in the user preference currencies file. In the Dynamic mode, the list shown in the currency prompt drop down is a result of a dynamic query specified in the same file. Customers can build some security into the rpd, so the list of currency preferences will be based on the user roles…BI Applications built a subject area: “Dynamic Currency Preference” to run this query, and give every user only the list of currency preferences required by his application roles. Adding Currency to an Amount Field When the user selects one of the items from the currency prompt, all the amounts in that page will show in the Currency corresponding to that preference. For example, if the user selects “Global Currency1” from the prompt, all data will be showing in Global Currency 1 as specified in the Configuration Manager. If the user select “Local Currency”, all amount fields will show in the Currency of the Business Unit selected in the BU filter of the same page. If there is no particular Business Unit selected in that filter, and the data selected by the query contains amounts in more than one currency (for example one BU has USD as a functional currency, the other has EUR as functional currency), then subtotals will not be available (cannot add USD and EUR amounts in one field), and depending on the set up (see next paragraph), the user may receive an error. There are two ways to add the Currency field to an amount metric: In the form of currency code, like USD, EUR…For this the user needs to add the field “Apps Common Currency Code” to the report. This field is in every subject area, usually under the table “Currency Tag” or “Currency Code”… In the form of currency symbol ($ for USD, € for EUR,…) For this, the user needs to format the amount metrics in the report as a currency column, by specifying the currency tag column in the Column Properties option in Column Actions drop down list. Typically this column should be the “BI Common Currency Code” available in every subject area. Select Column Properties option in the Edit list of a metric. In the Data Format tab, select Custom as Treat Number As. Enter the following syntax under Custom Number Format: [$:currencyTagColumn=Subjectarea.table.column] Where Column is the “BI Common Currency Code” defined to take the currency code value based on the currency preference chosen by the user in the Currency preference prompt.

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  • Throttling Cache Events

    - by dxfelcey
    The real-time eventing feature in Coherence is great for relaying state changes to other systems or to users. However, sometimes not all changes need to or can be sent to consumers. For instance; If rapid changes cannot be consumed or interpreted as fast as they are being sent. A user looking at changing Stock prices may only be able to interpret and react to 1 change per second. A client may be using low bandwidth connection, so rapidly sending events will only result in them being queued and delayed A large number of clients may need to be notified of state changes and sending 100 events p/s to 1000 clients cannot be supported with the available hardware, but 10 events p/s to 1000 clients can. Note this example assumes that many of the state changes are to the same value. One simple approach to throttling Coherence cache events is to use a cache store to capture changes to one cache (data cache) and insert those changes periodically in another cache (events cache). Consumers interested in state changes to entires in the first cache register an interest (event listener) against the second event cache. By using the cache store write-behind feature rapid updates to the same cache entry are coalesced so that updates are merged and written at the interval configured to the event cache. The time interval at which changes are written to the events cache can easily be configured using the write-behind delay time in the cache configuration, as shown below.   <caching-schemes>     <distributed-scheme>       <scheme-name>CustomDistributedCacheScheme</scheme-name>       <service-name>CustomDistributedCacheService</service-name>       <thread-count>1</thread-count>       <backing-map-scheme>         <read-write-backing-map-scheme>           <scheme-name>CustomRWBackingMapScheme</scheme-name>           <internal-cache-scheme>             <local-scheme />           </internal-cache-scheme>           <cachestore-scheme>             <class-scheme>               <scheme-name>CustomCacheStoreScheme</scheme-name>               <class-name>com.oracle.coherence.test.CustomCacheStore</class-name>               <init-params>                 <init-param>                   <param-type>java.lang.String</param-type>                   <param-value>{cache-name}</param-value>                 </init-param>                 <init-param>                   <param-type>java.lang.String</param-type>                   <!-- The name of the cache to write events to -->                   <param-value>cqc-test</param-value>                 </init-param>               </init-params>             </class-scheme>           </cachestore-scheme>           <write-delay>1s</write-delay>           <write-batch-factor>0</write-batch-factor>         </read-write-backing-map-scheme>       </backing-map-scheme>       <autostart>true</autostart>     </distributed-scheme>   </caching-schemes> The cache store implementation to perform this throttling is trivial and only involves overriding the basic cache store functions. public class CustomCacheStore implements CacheStore { private String publishingCacheName; private String sourceCacheName; public CustomCacheStore(String sourceCacheStore, String publishingCacheName) { this.publishingCacheName = publishingCacheName; this.sourceCacheName = sourceCacheName; } @Override public Object load(Object key) { return null; } @Override public Map loadAll(Collection keyCollection) { return null; } @Override public void erase(Object key) { if (sourceCacheName != publishingCacheName) { CacheFactory.getCache(publishingCacheName).remove(key); CacheFactory.log("Erasing entry: " + key, CacheFactory.LOG_DEBUG); } } @Override public void eraseAll(Collection keyCollection) { if (sourceCacheName != publishingCacheName) { for (Object key : keyCollection) { CacheFactory.getCache(publishingCacheName).remove(key); CacheFactory.log("Erasing collection entry: " + key, CacheFactory.LOG_DEBUG); } } } @Override public void store(Object key, Object value) { if (sourceCacheName != publishingCacheName) { CacheFactory.getCache(publishingCacheName).put(key, value); CacheFactory.log("Storing entry (key=value): " + key + "=" + value, CacheFactory.LOG_DEBUG); } } @Override public void storeAll(Map entryMap) { if (sourceCacheName != publishingCacheName) { CacheFactory.getCache(publishingCacheName).putAll(entryMap); CacheFactory.log("Storing entries: " + entryMap, CacheFactory.LOG_DEBUG); } } }  As you can see each cache store operation on the data cache results in a similar operation on event cache. This is a very simple pattern which has a lot of additional possibilities, but it also has a few drawbacks you should be aware of: This event throttling implementation will use additional memory as a duplicate copy of entries held in the data cache need to be held in the events cache too - 2 if the event cache has backups A data cache may already use a cache store, so a "multiplexing cache store pattern" must also be used to send changes to the existing and throttling cache store.  If you would like to try out this throttling example you can download it here. I hope its useful and let me know if you spot any further optimizations.

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  • WPF Window Style not working at runtime

    - by Christian Pena
    Hi, I created a WPF application in Visual Studio 2010 Express (C#) and added the text below to the Application.Resources in App.xaml. I see the style applied to the window in the designer, but when I run the application, the window background is white. Running in Windows XP on BootCamp on a MacBook Pro if that is a factor. Thanks in advance, Christian <Style TargetType="{x:Type Window}"> <Setter Property="Background"> <Setter.Value> <LinearGradientBrush StartPoint="0,0" EndPoint="0,1"> <GradientStop Offset="0" Color="WhiteSmoke" /> <GradientStop Offset="1" Color="Silver" /> </LinearGradientBrush> </Setter.Value> </Setter> <Setter Property="Padding" Value="20" /> </Style>

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  • What is the Relative Performance of Pseudo-Class and Custom Selectors?

    - by James Wiseman
    It's my understanding that, in terms of selector speed, that #ID selectors are fastest, followed by element selectors, and then .class selectors. I have always assumed that pseudo-class selectors and custom selectors (those in the form ':selector') are similar to .class selectors, but I realised that I'm just not sure. I realise that this does depend on the complexity of the code within the pseudo-class/custom selector, so I guess I'd like to know the answer with this excluded as factor. Any help would be appreciated. Thanks.

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