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  • Reflection velocity

    - by MindSeeker
    I'm trying to get a moving circular object to bounce (elastically) off of an immovable circular object. Am I doing this right? (The results look right, but I hate to trust that alone, and I can't find a tutorial that tackles this problem and includes the nitty gritty math/code to verify what I'm doing). If it is right, is there a better/faster/more elegant way to do this? Note that the object (this) is the moving circle, and the EntPointer object is the immovable circle. //take vector separating the two centers <x, y>, and then get unit vector of the result: MathVector2d unitnormal = MathVector2d(this -> Retxpos() - EntPointer -> Retxpos(), this -> Retypos() - EntPointer -> Retypos()).UnitVector(); //take tangent <-y, x> of the unitnormal: MathVector2d unittangent = MathVector2d(-unitnormal.ycomp, unitnormal.xcomp); MathVector2d V1 = MathVector2d(this -> Retxvel(), this -> Retyvel()); //Calculate the normal and tangent vector lengths of the velocity: (the normal changes, the tangent stays the same) double LengthNormal = DotProduct(unitnormal, V1); double LengthTangent = DotProduct(unittangent, V1); MathVector2d VelVecNewNormal = unitnormal.ScalarMultiplication(-LengthNormal); //the negative of what it was before MathVector2d VelVecNewTangent = unittangent.ScalarMultiplication(LengthTangent); //this stays the same MathVector2d NewVel = VectorAddition(VelVecNewNormal, VelVecNewTangent); //combine them xvel = NewVel.xcomp; //and then apply them yvel = NewVel.ycomp; Note also that this question is just about velocity, the position code is handled elsewhere (in other words, assume that this code is implemented at the exact moment that the circles begin to overlap). Thanks in advance for your help and time!

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  • Two Sessions All Humans Should Watch Right Now

    - by Geertjan
    At conferences, I definitely prefer technical sessions over any other kind of session. That's partly because I want to walk away from a conference with new libraries and APIs to play with, such as the AT&T ARO tool that I've been blogging about over the past few days thanks to being introduced to it in a great session by Doug Sillars at Oredev, in Malmo, Sweden. I only say the above to set the scene. And the scene is that I avoid sessions that deal with "agile topics" or whatever that means. I mean those sessions where you're meant to reflect on some way you're developing nothing in particular and then come away with new ways of doing that. I avoid those. Not because I don't necessarily like those or think I have nothing to learn, both of which I don't (or do, depending on how you read double negatives), but because there are so many sessions to attend that I focus on those that actually give me more technical knowledge that I can do something with immediately. Having said all that, here's two absolutely wonderful sessions (and probably many more but I really liked these two) presented at Oredev over the last few days, one by JB Rainsberger and the other by Woody Zuill, both very nice people who I met for the first time during the last few days, and who aren't paying me to promote them, and who're still struggling to figure out how to say my name. Whether you're a developer or manager or whatever you are, take this on trust, and simply watch these screencasts, hey, at most you're going to lose two hours of your life that you would've spent doing something else: Speaking for myself, I'm going to be watching both these presentations again several times in my life, that's for sure.

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  • Transformation?

    - by Joe G
    I started working at Oracle in 1997.  Since then, we (and most everyone) have been talking about transforming finance operations....but what does that mean exactly?  From my perspective, I thought it meant eliminate waste and menial tasks and giving your finance team more time to work on more strategic things.  That seems logical and simplistic, but how much progress have finance teams (and their IT departments) really made over the past fifteen years? I have yet to talk to a customer that doesn't have one amusing task that makes me chuckle.  Sometimes they still print hard copies of transactions to "file," or sometimes they print 700 pages of data to "analyze," or sometimes they cut and paste from one or more reports into a spreadsheet.  Upon hearing these things, my first question is always, "Why do you do that?" to which their response is rarely the same.    Sometimes it's related to trust (both the employee and the system).  Sometimes, it's habit-based.  And sometimes it is just impossible to accomplish the end result without some manual effort. I will say that I used to print nearly everything that I needed to review.  Partly, because I liked having the ability to scribble notes on the paper, and partly, because it was uncomfortable to read online.  However, I have changed. Rarely do I print anything anymore.  It's easier for me to read and notate online, and well, I guess I've just changed my habits. So where do you think our resistance to change comes from?  Is it truly deficits in our systems, or is it our own personal resistance to change?  What's your most annoying & untransformed task?

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  • Guidelines for creating referentially transparent callables

    - by max
    In some cases, I want to use referentially transparent callables while coding in Python. My goals are to help with handling concurrency, memoization, unit testing, and verification of code correctness. I want to write down clear rules for myself and other developers to follow that would ensure referential transparency. I don't mind that Python won't enforce any rules - we trust ourselves to follow them. Note that we never modify functions or methods in place (i.e., by hacking into the bytecode). Would the following make sense? A callable object c of class C will be referentially transparent if: Whenever the returned value of c(...) depends on any instance attributes, global variables, or disk files, such attributes, variables, and files must not change for the duration of the program execution; the only exception is that instance attributes may be changed during instance initialization. When c(...) is executed, no modifications to the program state occur that may affect the behavior of any object accessed through its "public interface" (as defined by us). If we don't put any restrictions on what "public interface" includes, then rule #2 becomes: When c(...) is executed, no objects are modified that are visible outside the scope of c.__call__. Note: I unsuccessfully tried to ask this question on SO, but I'm hoping it's more appropriate to this site.

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  • Tuning WebServer Response -

    - by Vedran Wex Maricevic
    I have this sam e question on StackOverflow and I was advised to ask it here hoping for more information. Here is the question: I am in rather unfavorable situation. I have aspdotneststore front e-commerce application and search addon called VibeTrib. I dont have source code for both of those. Store that runs on StoreFront and VibeTrib has close to 250k products. Also we have lots of filters. I spoke to ViTrib reps, and they want extra money so they could optimize Queries that they use. Money they require is nto a big deal, but the problem is I dont trust them anymore. What we got is much different then wha is being advertised. To cut the long story short. I am runing the store on Amazon AWS now, and regardless of what DB (MsSQL 2012) server I set (I tried 32GB RAM monsters instances) it is slow. Ajax search uses Full Text search and it displays search keywords relatively fast, but once the search is performed ( to display all results) it is still slow.!!! There is something that I could to do accelerate the speed on my own end? I do have full control over EC2 Instance (Web server Server 2012 and IIS 8). Can I set IIS to step in for the search and cache some of it? I was hoping to cache at least some most common words. My best bet is IIS 8 :) Is there any help in my case? Thanks

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  • How to quantify your "slow" development machine?

    - by lance
    ( Please provide the question this one duplicates. I'm disappointed I couldn't find it. ) My development machine is "slow". I wait on it "a lot". I've been asked by decision makers who want to help to fairly and accurately measure that time. How do you quantify the amount of time you spend waiting on the computer (during compiles, waiting for apps to open every day, etc). Is there software which effectively reports on this sort of thing? Is there an OS metric (I/O something something, pagefile swapping frequency, etc, etc) that captures and communicates this particularly well? Some sort of benchmark you'd recommend me testing against?

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  • Open Source Highlight: namebench

    - by eddraper
    DNS is a big deal.  Even small incremental changes to improve its performance can yield significant value due to the vast quantity of look-ups required when using the internet.  Until now, It’s always been one of those things I had to kinda take on faith… was my ISP doing a good job?  Are those public DNS server really that much faster?  What about security and privacy concerns? Let me introduce you to namebench.  This is the kinda tool I really love – one that immediately delivers value and is almost over-the-top OCD in its attention to detail. Trust me, this tool is utterly ruthless in it’s quest for getting it right – you’re not left with a big question mark after it presents its data.  The results are conclusive and actionable.  Here’s what is does: It hunts down the fastest DNS servers from your desktop that it can find using thousands of requests.  No, it doesn’t pop up this little dialog in 10 seconds to give you some “off the cuff” answer from a handful of providers.  It takes the better part of 10-15 minutes to run.  When it finishes, it presents you with a veritable horn-o-plenty of data.  Mean response duration, response distribution, bad data,  no stone is left un-turned. Check it out.  You’ll dig it.

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  • How can I fix the #c3284d# malvertising hack on my website?

    - by crm
    For the past couple of weeks at semi regular intervals, this website has had the #c3284d# malware code inserted into some of its .php files. Also the .htaccess file had its equivelant code inserted. I have, on many occasions removed the malicious code, replaced files, changed the ftp password on my ftp client (which is CoreFTP), changed the connection method to FTPS for more secure storage of the password (instead of plain text). I have also scanned my computer several times using AVG and Windows Defender which have found no malware on my computer which might have been storing my ftp passwords. I used Sucuri SiteCheck to check my website which says my website is clean of malware which is bizarre because I just attempted to click one of the links on the site a minute ago and it linked me to another one of these random stats.php sites, even though it appears I have gotten rid of the #c3284d# code again (which will no doubt be re-inserted somehow in an hour or so).. Has anyone found an actual viable solution for this malware hack? I have done just about all of the things suggested here and here and the problem still persists. Currently when I click on a link within the sites navigation menu within Google Chrome I get googles Malware warning page: Warning: Something's Not Right Here! oxsanasiberians.com contains malware. Your computer might catch a virus if you visit this site. Google has found that malicious software may be installed onto your computer if you proceed. If you've visited this site in the past or you trust this site, it's possible that it has just recently been compromised by a hacker. You should not proceed. Why not try again tomorrow or go somewhere else? We have already notified oxsanasiberians.com that we found malware on the site. For more about the problems found on oxsanasiberians.com, visit the Google Safe Browsing diagnostic page. I'm wondering if it is possible that the Google Chrome browser I am using has itself been hacked? Does anyone else get re-directed when clicking links on the the website?

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  • Is it reasonable to null guard every single dereferenced pointer?

    - by evadeflow
    At a new job, I've been getting flagged in code reviews for code like this: PowerManager::PowerManager(IMsgSender* msgSender) : msgSender_(msgSender) { } void PowerManager::SignalShutdown() { msgSender_->sendMsg("shutdown()"); } I'm told that last method should read: void PowerManager::SignalShutdown() { if (msgSender_) { msgSender_->sendMsg("shutdown()"); } } i.e., I must put a NULL guard around the msgSender_ variable, even though it is a private data member. It's difficult for me to restrain myself from using expletives to describe how I feel about this piece of 'wisdom'. When I ask for an explanation, I get a litany of horror stories about how some junior programmer, some-year, got confused about how a class was supposed to work and accidentally deleted a member he shouldn't have (and set it to NULL afterwards, apparently), and things blew up in the field right after a product release, and we've "learned the hard way, trust us" that it's better to just NULL check everything. To me, this feels like cargo cult programming, plain and simple. A few well-meaning colleagues are earnestly trying to help me 'get it' and see how this will help me write more robust code, but... I can't help feeling like they're the ones who don't get it. Is it reasonable for a coding standard to require that every single pointer dereferenced in a function be checked for NULL first—even private data members? (Note: To give some context, we make a consumer electronics device, not an air traffic control system or some other 'failure-equals-people-die' product.) EDIT: In the above example, the msgSender_ collaborator isn't optional. If it's ever NULL, it indicates a bug. The only reason it is passed into the constructor is so PowerManager can be tested with a mock IMsgSender subclass.

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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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  • Approach to Authenticate Clients to TCP Server

    - by dab
    I'm writing a Server/Client application where clients will connect to the server. What I want to do, is make sure that the client connecting to the server is actually using my protocol and I can "trust" the data being sent from the client to the server. What I thought about doing is creating a sort of hash on the client's machine that follows a particular algorithm. What I did in a previous version was took their IP address, the client version, and a few other attributes of the client and sent it as a calculated hash to the server, who then took their IP, and the version of the protocol the client claimed to be using, and calculated that number to see if they matched. This works ok until you get clients that connect from within a router environment where their internal IP is different from their external IP. My fix for this was to pass the client's internal IP used to calculate this hash with the authentication protocol. My fear is this approach is not secure enough. Since I'm passing the data used to create the "auth hash". Here's an example of what I'm talking about: Client IP: 192.168.1.10, Version: 2.4.5.2 hash = 2*4*5*1 * (1+9+2) * (1+6+8) * (1) * (1+0) Client Connects to Server client sends: auth hash ip version Server calculates that info, and accepts or denies the hash. Before I go and come up with another algorithm to prove a client can provide data a server (or use this existing algorithm), I was wondering if there are any existing, proven, and secure systems out there for generating a hash that both sides can generate with general knowledge. The server won't know about the client until the very first connection is established. The protocol's intent is to manage a network of clients who will be contributing data to the server periodically. New clients will be added simply by connecting the client to the server and "registering" with the server. So a client connects to the server for the first time, and registers their info (mac address or some other kind of unique computer identifier), then when they connect again, the server will recognize that client as a previous person and associate them with their data in the database.

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  • user height and weight in sql

    - by Samuel
    We are planning to capture a user's height and weight and am looking for ideas on representing them in sql. I have the following questions in mind weight can be expressed in kilograms and grams and height in meters and centimeters, so should I capture them as a BigDecimal with an appropriate precision and scale or capture them as vanilla strings and do the manipulation in the user interface. Note: I am planning to capture the kilograms and grams separately in the user interface. should the metric of measurement be part of the sql (i.e. the end user might want to view this information in pounds, inches according to his preference) OR Should I just support kilograms / meters in the database and do the conversion while showing this in the user interface

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  • Interpolation on Cubism graphs

    - by Abe Stanway
    Cubism was designed, by mbostock's own words, for maximum information density - which means it generally wants to display one datapoint per pixel. While this is useful in many cases, it doesn't help when your data itself is not that dense. In these cases, you get ugly, staccato-style graphs like so: Is there a way to interpolate my data/graph within Cubism to show a nice, smoothed graph? EDIT: After adding keepLastValue to the metric, I get this: Here is the same data as shown in Graphite: I would like to smooth the Cubism view to look more like Graphite (with the added awesomeness of the horizon overplotting)

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  • Get averages from pre-aggregated reports in mongodb

    - by Chris
    I've got a database with pre-aggregated metrics similar to the one outlined in this use case: http://docs.mongodb.org/manual/use-cases/pre-aggregated-reports/ I have a daily collection with a subdocument for hour and minute metrics, and a 'metadata.date' entry for midnight on the day it represents. I also have a monthly collection with a day subdocument for each day. If I want to get an average of a metric over the past eight or so days how can I do that with the aggregation framework? Is the aggregation framework not the right tool for this since it's already pre-aggregated?

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  • Is directly executing SQL bad app design?

    - by Michael Lowman
    I'm developing an iOS application that's a manager/viewer for another project. The idea is the app will be able to process the data stored in a database into a number of visualizations-- the overall effect being similar to cacti. I'm making the visualizations fully user-configurable: the user defines what she wants to see and adds restrictions. She might specify, for instance, to graph a metric over the last three weeks with user accounts that are currently active and aren't based in the United States. My problem is that the only design I can think of is more or less passing direct SQL from the iOS app to the backend server to be executed against the database. I know it's bad practice and everything should be written in terms of stored procedures. But how else do I maintain enough flexiblity to keep fully user-defined queries? While the application does compose the SQL, direct SQL is never visible or injectable by the user. That's all abstracted away in UIDateTimeChoosers, UIPickerViews, and the like.

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  • which technology or strategy a new / inexperienced freelancer should use to earn profit? [closed]

    - by w3softdev
    this question has re-posted by me in the following group if you find suitable to answer this question then please click on the link attached here or copy paste this in your browser.. http://answers.onstartups.com/questions/32767/which-technology-or-strategy-a-new-inexperienced-freelancer-should-use-to-earn Well it is my very first Question in this section and i really don't know whether my query relate to this section or not. anyway i have some awkward query. (however, it is like a bit story but i guess it is necessary to know some background knowledge of me.) Actually I m fresh recent grad who has just started his freelancing work. In due course i have got a project to develop website for a middle scale business (travel agent). As I don't trust on my client whether he will pay to me in full or not after the completion of website, i want to use cheaper and efficient technology so that how much he would pay I could got at least few units of % of profit. As i have learnt ASP.NET and when I inquired about the expense in Hosting of my website i got the recommendation to develop my web app using the combination PHP and MYSQL instead the asp.net + ms sql. And the problem is I don't know PHP. should I learn PHP and or work in what i m comfortable with and should try to cover whole deserved money. (as it is my first project so i m also advised that i may got some loss in starting but contrary to this i don't want to go in loss and want to earn appropriate profit)

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  • Getting expired domain name - most effective route?

    - by kcdwayne
    There is a domain name I have been wanting for years that was used as a parked page (read: cybersquatted) that has entered into WHOIS's redemptionPeriod stage. The domain has been expired for 61 days now - after contacting the Registar, they informed me that it would stay in redemption for 75 days. After which, it would either be sold to resellers, or sent back to the public registry. (I have since sent a followup message requesting the reseller they use.) My question is: What is the best way to proceed? I know there is at least one competitor that would love to have this name, but I'm unsure if they even know it's expiring. I did not tell the Registar the domain in question, as they seem geared towards cybersquatting, and I do not trust them. Domain Front Running sucks. Should I use a backorder service? Should I just take my chances and try to grab it after75 days? I checked an auctionhouse by manually browsing their expired domains - it wasn't there.

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  • Are these 2 strings equal?

    - by Shawn Cicoria
    I spent way too many hours on this one. I was going through full configuration of ADFS v2 with WCF active client scenarios and using self generated certificates, had all things lined up perfectly.  Using the certificate snap in I just copied the thumbprint into the IdentityModel section (trusted issuers) in my service config.  var one = "?ecb8fd950978d94ae21d4f073227fdc2718bdb96"; var two = "ecb8fd950978d94ae21d4f073227fdc2718bdb96"; What ended up is in the first, there’s a buried nonprintable series of characters (‎ – or E2 80 8E in 0x format). 2 lessons, turn on tracing sooner and don’t trust Copy & Paste – all the time.  I ended up creating a quick Issuer Name Registry class so I could debug and finally saw the issue. namespace MyService { public class IssuerValidator : ConfigurationBasedIssuerNameRegistry { public IssuerValidator() :base() { } public IssuerValidator(XmlNodeList xml) : base(xml) { } public override string GetIssuerName(System.IdentityModel.Tokens.SecurityToken securityToken) { X509SecurityToken token = securityToken as X509SecurityToken; if (token == null) { return "who cares"; } else { return token.Certificate.Thumbprint; } } } I do have a utility I wrote to navigate the cert store and emit the thumbprint to avoid these issues, I just didn’t have it available on my machine at the time.

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  • Phishing attack stuck with jsp loginAction.do page? [closed]

    - by user970533
    I 'm testing a phishing website on a staged replica of an jsp web-application. I'm doing the usual attack which involves changing the post and action field of source code to divert to my own written jsp script capture the logins and redirect the victim to the original website. It looks easy but trust me its has been me more then 2 weeks I cannot write the logins to the text file. I have tested the jsp page on my local wamp server it works fine. In staged when I click on the ok button for user/password field I'm taken to loginAction.do script. I checked this using tamper data add on on firefox. The only way I was able to make my script run was to use burp proxy intercept the request and change action parameter to refer my uploaded script. I want to know what does an loginAction.do? I have googled it - its quite common to see it in jsp application. I have checked the code; there is nothing that tells me why the page always point to the .do script instead of mine. Is there some kind of redirection in tomcat configuration. I like to know. I'm unable to exploit this attack vector? I need the community help

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  • javascript error : periodLookup[periodStr] is undefined, why is it throwing this error?

    - by Mo
    Hi i have this method: set_period_help_text: function(periodInput){ var metric = MonitorMetric.getSelectedMetric(); var periodStr = $('select[name=metric_period]').val(); var datapoints = Number(periodInput.attr("value")); var period = datapoints * periodLookup[periodStr][0]; } var periodLookup = { "OneMinute": [1, "minute"], "FiveMinute": [5, "minute"], "OneHour": [1, "hour"], "OneDay": [1, "day"], "OneWeek": [1, "week"] }; where var periodStr is being retrived from a dropdown menue that only has the values: "OneMinute" "FiveMinute" "OneHour" "OneDay" "OneWeek" i get a java script error when the page loads: periodLookup[periodStr] is undefined [Break on this error] var period = datapoints * periodLookup[periodStr][0];

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  • Retrieve data like rework %, schedule and effort varience from Microsoft Project

    - by Ram
    Hi, I need to generate various metric from my MS project file for the period of one month. I need to generate following reports Schedule Variance Effort Variance Rework Percentage Wasted Efforts For rework percentage, I am using condition like the task.Start date should be greater than or equal to the start date and task.Finish date should be less than or equal to finish date. but I am concerned about the tasks those are starting before the start date and ending before the end date. In such situation I only need the rework % for the number of hrs spent during start and end and not for the hrs spent before start date. Same thing applies to the task which are starting before end date but ending after end date. Any pointer would be great help. Thanks

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  • Load and Web Performance Testing using Visual Studio Ultimate 2010-Part 3

    - by Tarun Arora
    Welcome back once again, in Part 1 of Load and Web Performance Testing using Visual Studio 2010 I talked about why Performance Testing the application is important, the test tools available in Visual Studio Ultimate 2010 and various test rig topologies, in Part 2 of Load and Web Performance Testing using Visual Studio 2010 I discussed the details of web performance & load tests as well as why it’s important to follow a goal based pattern while performance testing your application. In part 3 I’ll be discussing Test Result Analysis, Test Result Drill through, Test Report Generation, Test Run Comparison, Asp.net Profiler and some closing thoughts. Test Results – I see some creepy worms! In Part 2 we put together a web performance test and a load test, lets run the test to see load test to see how the Web site responds to the load simulation. While the load test is running you will be able to see close to real time analysis in the Load Test Analyser window. You can use the Load Test Analyser to conduct load test analysis in three ways: Monitor a running load test - A condensed set of the performance counter data is maintained in memory. To prevent the results memory requirements from growing unbounded, up to 200 samples for each performance counter are maintained. This includes 100 evenly spaced samples that span the current elapsed time of the run and the most recent 100 samples.         After the load test run is completed - The test controller spools all collected performance counter data to a database while the test is running. Additional data, such as timing details and error details, is loaded into the database when the test completes. The performance data for a completed test is loaded from the database and analysed by the Load Test Analyser. Below you can see a screen shot of the summary view, this provides key results in a format that is compact and easy to read. You can also print the load test summary, this is generated after the test has completed or been stopped.         Analyse the load test results of a previously run load test – We’ll see this in the section where i discuss comparison between two test runs. The performance counters can be plotted on the graphs. You also have the option to highlight a selected part of the test and view details, drill down to the user activity chart where you can hover over to see more details of the test run.   Generate Report => Test Run Comparisons The level of reports you can generate using the Load Test Analyser is astonishing. You have the option to create excel reports and conduct side by side analysis of two test results or to track trend analysis. The tools also allows you to export the graph data either to MS Excel or to a CSV file. You can view the ASP.NET profiler report to conduct further analysis as well. View Data and Diagnostic Attachments opens the Choose Diagnostic Data Adapter Attachment dialog box to select an adapter to analyse the result type. For example, you can select an IntelliTrace adapter, click OK and open the IntelliTrace summary for the test agent that was used in the load test.   Compare results This creates a set of reports that compares the data from two load test results using tables and bar charts. I have taken these screen shots from the MSDN documentation, I would highly recommend exploring the wealth of knowledge available on MSDN. Leaving Thoughts While load testing the application with an excessive load for a longer duration of time, i managed to bring the IIS to its knees by piling up a huge queue of requests waiting to be processed. This clearly means that the IIS had run out of threads as all the threads were busy processing existing request, one easy way of fixing this is by increasing the default number of allocated threads, but this might escalate the problem. The better suggestion is to try and drill down to the actual root cause of the problem. When ever the garbage collection runs it stops processing any pages so all requests that come in during that period are queued up, but realistically the garbage collection completes in fraction of a a second. To understand this better lets look at the .net heap, it is divided into large heap and small heap, anything greater than 85kB in size will be allocated to the Large object heap, the Large object heap is non compacting and remember large objects are expensive to move around, so if you are allocating something in the large object heap, make sure that you really need it! The small object heap on the other hand is divided into generations, so all objects that are supposed to be short-lived are suppose to live in Gen-0 and the long living objects eventually move to Gen-2 as garbage collection goes through.  As you can see in the picture below all < 85 KB size objects are first assigned to Gen-0, when Gen-0 fills up and a new object comes in and finds Gen-0 full, the garbage collection process is started, the process checks for all the dead objects and assigns them as the valid candidate for deletion to free up memory and promotes all the remaining objects in Gen-0 to Gen-1. So in the future when ever you clean up Gen-1 you have to clean up Gen-0 as well. When you fill up Gen – 0 again, all of Gen – 1 dead objects are drenched and rest are moved to Gen-2 and Gen-0 objects are moved to Gen-1 to free up Gen-0, but by this time your Garbage collection process has started to take much more time than it usually takes. Now as I mentioned earlier when garbage collection is being run all page requests that come in during that period are queued up. Does this explain why possibly page requests are getting queued up, apart from this it could also be the case that you are waiting for a long running database process to complete.      Lets explore the heap a bit more… What is really a case of crisis is when the objects are living long enough to make it to Gen-2 and then dying, this is definitely a high cost operation. But sometimes you need objects in memory, for example when you cache data you hold on to the objects because you need to use them right across the user session, which is acceptable. But if you wanted to see what extreme caching can do to your server then write a simple application that chucks in a lot of data in cache, run a load test over it for about 10-15 minutes, forcing a lot of data in memory causing the heap to run out of memory. If you get to such a state where you start running out of memory the IIS as a mode of recovery restarts the worker process. It is great way to free up all your memory in the heap but this would clear the cache. The problem with this is if the customer had 10 items in their shopping basket and that data was stored in the application cache, the user basket will now be empty forcing them either to get frustrated and go to a competitor website or if the customer is really patient, give it another try! How can you address this, well two ways of addressing this; 1. Workaround – A x86 bit processor only allows a maximum of 4GB of RAM, this means the machine effectively has around 3.4 GB of RAM available, the OS needs about 1.5 GB of RAM to run efficiently, the IIS and .net framework also need their share of memory, leaving you a heap of around 800 MB to play with. Because Team builds by default build your application in ‘Compile as any mode’ it means the application is build such that it will run in x86 bit mode if run on a x86 bit processor and run in a x64 bit mode if run on a x64 but processor. The problem with this is not all applications are really x64 bit compatible specially if you are using com objects or external libraries. So, as a quick win if you compiled your application in x86 bit mode by changing the compile as any selection to compile as x86 in the team build, you will be able to run your application on a x64 bit machine in x86 bit mode (WOW – By running Windows on Windows) and what that means is, you could use 8GB+ worth of RAM, if you take away everything else your application will roughly get a heap size of at least 4 GB to play with, which is immense. If you need a heap size of more than 4 GB you have either build a software for NASA or there is something fundamentally wrong in your application. 2. Solution – Now that you have put a workaround in place the IIS will not restart the worker process that regularly, which means you can take a breather and start working to get to the root cause of this memory leak. But this begs a question “How do I Identify possible memory leaks in my application?” Well i won’t say that there is one single tool that can tell you where the memory leak is, but trust me, ‘Performance Profiling’ is a great start point, it definitely gets you started in the right direction, let’s have a look at how. Performance Wizard - Start the Performance Wizard and select Instrumentation, this lets you measure function call counts and timings. Before running the performance session right click the performance session settings and chose properties from the context menu to bring up the Performance session properties page and as shown in the screen shot below, check the check boxes in the group ‘.NET memory profiling collection’ namely ‘Collect .NET object allocation information’ and ‘Also collect the .NET Object lifetime information’.    Now if you fire off the profiling session on your pages you will notice that the results allows you to view ‘Object Lifetime’ which shows you the number of objects that made it to Gen-0, Gen-1, Gen-2, Large heap, etc. Another great feature about the profile is that if your application has > 5% cases where objects die right after making to the Gen-2 storage a threshold alert is generated to alert you. Since you have the option to also view the most expensive methods and by capturing the IntelliTrace data you can drill in to narrow down to the line of code that is the root cause of the problem. Well now that we have seen how crucial memory management is and how easy Visual Studio Ultimate 2010 makes it for us to identify and reproduce the problem with the best of breed tools in the product. Caching One of the main ways to improve performance is Caching. Which basically means you tell the web server that instead of going to the database for each request you keep the data in the webserver and when the user asks for it you serve it from the webserver itself. BUT that can have consequences! Let’s look at some code, trust me caching code is not very intuitive, I define a cache key for almost all searches made through the common search page and cache the results. The approach works fine, first time i get the data from the database and second time data is served from the cache, significant performance improvement, EXCEPT when two users try to do the same operation and run into each other. But it is easy to handle this by adding the lock as you can see in the snippet below. So, as long as a user comes in and finds that the cache is empty, the user locks and starts to get the cache no more concurrency issues. But lets say you are processing 10 requests per second, by the time i have locked the operation to get the results from the database, 9 other users came in and found that the cache key is null so after i have come out and populated the cache they will still go in to get the results again. The application will still be faster because the next set of 10 users and so on would continue to get data from the cache. BUT if we added another null check after locking to build the cache and before actual call to the db then the 9 users who follow me would not make the extra trip to the database at all and that would really increase the performance, but didn’t i say that the code won’t be very intuitive, may be you should leave a comment you don’t want another developer to come in and think what a fresher why is he checking for the cache key null twice !!! The downside of caching is, you are storing the data outside of the database and the data could be wrong because the updates applied to the database would make the data cached at the web server out of sync. So, how do you invalidate the cache? Well if you only had one way of updating the data lets say only one entry point to the data update you can write some logic to say that every time new data is entered set the cache object to null. But this approach will not work as soon as you have several ways of feeding data to the system or your system is scaled out across a farm of web servers. The perfect solution to this is Micro Caching which means you cache the query for a set time duration and invalidate the cache after that set duration. The advantage is every time the user queries for that data with in the time span for which you have cached the results there are no calls made to the database and the data is served right from the server which makes the response immensely quick. Now figuring out the appropriate time span for which you micro cache the query results really depends on the application. Lets say your website gets 10 requests per second, if you retain the cache results for even 1 minute you will have immense performance gains. You would reduce 90% hits to the database for searching. Ever wondered why when you go to e-bookers.com or xpedia.com or yatra.com to book a flight and you click on the book button because the fare seems too exciting and you get an error message telling you that the fare is not valid any more. Yes, exactly => That is a cache failure! These travel sites or price compare engines are not going to hit the database every time you hit the compare button instead the results will be served from the cache, because the query results are micro cached, its a perfect trade-off, by micro caching the results the site gains 100% performance benefits but every once in a while annoys a customer because the fare has expired. But the trade off works in the favour of these sites as they are still able to process up to 30+ page requests per second which means cater to the site traffic by may be losing 1 customer every once in a while to a competitor who is also using a similar caching technique what are the odds that the user will not come back to their site sooner or later? Recap   Resources Below are some Key resource you might like to review. I would highly recommend the documentation, walkthroughs and videos available on MSDN. You can always make use of Fiddler to debug Web Performance Tests. Some community test extensions and plug ins available on Codeplex might also be of interest to you. The Road Ahead Thank you for taking the time out and reading this blog post, you may also want to read Part I and Part II if you haven’t so far. If you enjoyed the post, remember to subscribe to http://feeds.feedburner.com/TarunArora. Questions/Feedback/Suggestions, etc please leave a comment. Next ‘Load Testing in the cloud’, I’ll be working on exploring the possibilities of running Test controller/Agents in the Cloud. See you on the other side! Thank You!   Share this post : CodeProject

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  • Oracle Enterprise Manager users present today at Oracle Users Forum

    - by Anand Akela
    Oracle Users Forum starts in a few minutes at Moscone West, Levels 2 & 3. There are more than hundreds of Oracle user sessions during the day. Many Oracle Oracle Enterprise Manager users are presenting today as well.  In addition, we will have a Twitter Chat today from 11:30 AM to 12:30 PM with IOUG leaders, Enterprise Manager SIG contributors and many speakers. You can participate in the chat using hash tag #em12c on Twitter.com or by going to  tweetchat.com/room/em12c      (Needs Twitter credential for participating).  Feel free to join IOUG and Enterprise team members at the User Group Pavilion on 2nd Floor, Moscone West. RSVP by going http://tweetvite.com/event/IOUG  . Don't miss the Oracle Open World welcome keynote by Larry Ellison this evening at 5 PM . Here is the complete list of Oracle Enterprise Manager sessions during the Oracle Users Forum : Time Session Title Speakers Location 8:00AM - 8:45AM UGF4569 - Oracle RAC Migration with Oracle Automatic Storage Management and Oracle Enterprise Manager 12c VINOD Emmanuel -Database Engineering, Dell, Inc. Wendy Chen - Sr. Systems Engineer, Dell, Inc. Moscone West - 2011 8:00AM - 8:45AM UGF10389 -  Monitoring Storage Systems for Oracle Enterprise Manager 12c Anand Ranganathan - Product Manager, NetApp Moscone West - 2016 9:00AM - 10:00AM UGF2571 - Make Oracle Enterprise Manager Sing and Dance with the Command-Line Interface Ray Smith - Senior Database Administrator, Portland General Electric Moscone West - 2011 10:30AM - 11:30AM UGF2850 - Optimal Support: Oracle Enterprise Manager 12c Cloud Control, My Oracle Support, and More April Sims - DBA, Southern Utah University Moscone West - 2011 12:30PM-2:00PM UGF5131 - Migrating from Oracle Enterprise Manager 10g Grid Control to 12c Cloud Control    Leighton Nelson - Database Administrator, Mercy Moscone West - 2011 2:15PM-3:15PM UGF6511 -  Database Performance Tuning: Get the Best out of Oracle Enterprise Manager 12c Cloud Control Mike Ault - Oracle Guru, TEXAS MEMORY SYSTEMS INC Tariq Farooq - CEO/Founder, BrainSurface Moscone West - 2011 3:30PM-4:30PM UGF4556 - Will It Blend? Verifying Capacity in Server and Database Consolidations Jeremiah Wilton - Database Technology, Blue Gecko / DatAvail Moscone West - 2018 3:30PM-4:30PM UGF10400 - Oracle Enterprise Manager 12c: Monitoring, Metric Extensions, and Configuration Best Practices Kellyn Pot'Vin - Sr. Technical Consultant, Enkitec Moscone West - 2011 Stay Connected: Twitter |  Face book |  You Tube |  Linked in |  Newsletter

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  • Laissez les bon temps rouler! (Microsoft BI Conference 2010)

    - by smisner
    "Laissez les bons temps rouler" is a Cajun phrase that I heard frequently when I lived in New Orleans in the mid-1990s. It means "Let the good times roll!" and encapsulates a feeling of happy expectation. As I met with many of my peers and new acquaintances at the Microsoft BI Conference last week, this phrase kept running through my mind as people spoke about their plans in their respective businesses, the benefits and opportunities that the recent releases in the BI stack are providing, and their expectations about the future of the BI stack. Notwithstanding some jabs here and there to point out the platform is neither perfect now nor will be anytime soon (along with admissions that the competitors are also not perfect), and notwithstanding several missteps by the event organizers (which I don't care to enumerate), the overarching mood at the conference was positive. It was a refreshing change from the doom and gloom hovering over several conferences that I attended in 2009. Although many people expect economic hardships to continue over the coming year or so, everyone I know in the BI field is busier than ever and expects to stay busy for quite a while. Self-Service BI Self-service was definitely a theme of the BI conference. In the keynote, Ted Kummert opened with a look back to a fairy tale vision of self-service BI that he told in 2008. At that time, the fairy tale future was a time when "every end user was able to use BI technologies within their job in order to move forward more effectively" and transitioned to the present time in which SQL Server 2008 R2, Office 2010, and SharePoint 2010 are available to deliver managed self-service BI. This set of technologies is presumably poised to address the needs of the 80% of users that Kummert said do not use BI today. He proceeded to outline a series of activities that users ought to be able to do themselves--from simple changes to a report like formatting or an addtional data visualization to integration of an additional data source. The keynote then continued with a series of demonstrations of both current and future technology in support of self-service BI. Some highlights that interested me: PowerPivot, of course, is the flagship product for self-service BI in the Microsoft BI stack. In the TechEd keynote, which was open to the BI conference attendees, Amir Netz (twitter) impressed the audience by demonstrating interactivity with a workbook containing 100 million rows. He upped the ante at the BI keynote with his demonstration of a future-state PowerPivot workbook containing over 2 billion records. It's important to note that this volume of data is being processed by a server engine, and not in the PowerPivot client engine. (Yes, I think it's impressive, but none of my clients are typically wrangling with 2 billion records at a time. Maybe they're thinking too small. This ability to work quickly with large data sets has greater implications for BI solutions than for self-service BI, in my opinion.) Amir also demonstrated KPIs for the future PowerPivot, which appeared to be easier to implement than in any other Microsoft product that supports KPIs, apart from simple KPIs in SharePoint. (My initial reaction is that we have one more place to build KPIs. Great. It's confusing enough. I haven't seen how well those KPIs integrate with other BI tools, which will be important for adoption.) One more PowerPivot feature that Amir showed was a graphical display of the lineage for calculations. (This is hugely practical, especially if you build up calculations incrementally. You can more easily follow the logic from calculation to calculation. Furthermore, if you need to make a change to one calculation, you can assess the impact on other calculations.) Another product demonstration will be available within the next 30 days--Pivot for Reporting Services. If you haven't seen this technology yet, check it out at www.getpivot.com. (It definitely has a wow factor, but I'm skeptical about its practicality. However, I'm looking forward to trying it out with data that I understand.) Michael Tejedor (twitter) demonstrated a feature that I think is really interesting and not emphasized nearly enough--overshadowed by PowerPivot, no doubt. That feature is the Microsoft Business Intelligence Indexing Connector, which enables search of the content of Excel workbooks and Reporting Services reports. (This capability existed in MOSS 2007, but was more cumbersome to implement. The search results in SharePoint 2010 are not only cooler, but more useful by describing whether the content is found in a table or a chart, for example.) This may yet be the dawning of the age of self-service BI - a phrase I've heard repeated from time to time over the last decade - but I think BI professionals are likely to stay busy for a long while, and need not start looking for a new line of work. Kummert repeatedly referenced strategic BI solutions in contrast to self-service BI to emphasize that self-service BI is not a replacement for the services that BI professionals provide. After all, self-service BI does not appear magically on user desktops (or whatever device they want to use). A supporting infrastructure is necessary, and grows in complexity in proportion to the need to simplify BI for users. It's one thing to hear the party line touted by Microsoft employees at the BI keynote, but it's another to hear from the people who are responsible for implementing and supporting it within an organization. Rob Collie (blog | twitter), Kasper de Jonge (blog | twitter), Vidas Matelis (site | twitter), and I were invited to join Andrew Brust (blog | twitter) as he led a Birds of a Feather session at TechEd entitled "PowerPivot: Is It the BI Deal-Changer for Developers and IT Pros?" I would single out the prevailing concern in this session as the issue of control. On one side of this issue were those who were concerned that they would lose control once PowerPivot is implemented. On the other side were those who believed that data should be freely accessible to users in PowerPivot, and even acknowledgment that users would get the data they want even if it meant they would have to manually enter into a workbook to have it ready for analysis. For another viewpoint on how PowerPivot played out at the conference, see Rob Collie's observations. Collaborative BI I have been intrigued by the notion of collaborative BI for a very long time. Before I discovered BI, I was a Lotus Notes developer and later a manager of developers, working in a software company that enabled collaboration in the legal industry. Not only did I help create collaborative systems for our clients, I created a complete project management from the ground up to collaboratively manage our custom development work. In that case, collaboration involved my team, my client contacts, and me. I was also able to produce my own BI from that system as well, but didn't know that's what I was doing at the time. Only in recent years has SharePoint begun to catch up with the capabilities that I had with Lotus Notes more than a decade ago. Eventually, I had the opportunity at that job to formally investigate BI as another product offering for our software, and the rest - as they say - is history. I built my first data warehouse with Scott Cameron (who has also ventured into the authoring world by writing Analysis Services 2008 Step by Step and was at the BI Conference last week where I got to reminisce with him for a bit) and that began a career that I never imagined at the time. Fast forward to 2010, and I'm still lauding the virtues of collaborative BI, if only the tools will catch up to my vision! Thus, I was anxious to see what Donald Farmer (blog | twitter) and Rita Sallam of Gartner had to say on the subject in their session "Collaborative Decision Making." As I suspected, the tools aren't quite there yet, but the vendors are moving in the right direction. One thing I liked about this session was a non-Microsoft perspective of the state of the industry with regard to collaborative BI. In addition, this session included a better demonstration of SharePoint collaborative BI capabilities than appeared in the BI keynote. Check out the video in the link to the session to see the demonstration. One of the use cases that was demonstrated was linking from information to a person, because, as Donald put it, "People don't trust data, they trust people." The Microsoft BI Stack in General A question I hear all the time from students when I'm teaching is how to know what tools to use when there is overlap between products in the BI stack. I've never taken the time to codify my thoughts on the subject, but saw that my friend Dan Bulos provided good insight on this topic from a variety of perspectives in his session, "So Many BI Tools, So Little Time." I thought one of his best points was that ideally you should be able to design in your tool of choice, and then deploy to your tool of choice. Unfortunately, the ideal is yet to become real across the platform. The closest we come is with the RDL in Reporting Services which can be produced from two different tools (Report Builder or Business Intelligence Development Studio's Report Designer), manually, or by a third-party or custom application. I have touted the idea for years (and publicly said so about 5 years ago) that eventually more products would be RDL producers or consumers, but we aren't there yet. Maybe in another 5 years. Another interesting session that covered the BI stack against a backdrop of competitive products was delivered by Andrew Brust. Andrew did a marvelous job of consolidating a lot of information in a way that clearly communicated how various vendors' offerings compared to the Microsoft BI stack. He also made a particularly compelling argument about how the existence of an ecosystem around the Microsoft BI stack provided innovation and opportunities lacking for other vendors. Check out his presentation, "How Does the Microsoft BI Stack...Stack Up?" Expo Hall I had planned to spend more time in the Expo Hall to see who was doing new things with the BI stack, but didn't manage to get very far. Each time I set out on an exploratory mission, I got caught up in some fascinating conversations with one or more of my peers. I find interacting with people that I meet at conferences just as important as attending sessions to learn something new. There were a couple of items that really caught me eye, however, that I'll share here. Pragmatic Works. Whether you develop SSIS packages, build SSAS cubes, or author SSRS reports (or all of the above), you really must take a look at BI Documenter. Brian Knight (twitter) walked me through the key features, and I must say I was impressed. Once you've seen what this product can do, you won't want to document your BI projects any other way. You can download a free single-user database edition, or choose from more feature-rich standard or professional editions. Microsoft Press ebooks. I also stopped by the O'Reilly Media booth to meet some folks that one of my acquisitions editors at Microsoft Press recommended. In case you haven't heard, Microsoft Press has partnered with O'Reilly Media for distribution and publishing. Apart from my interest in learning more about O'Reilly Media as an author, an advertisement in their booth caught me eye which I think is a really great move. When you buy Microsoft Press ebooks through the O'Reilly web site, you can receive it in any (or all) of the following formats where possible: PDF, epub, .mobi for Kindle and .apk for Android. You also have lifetime DRM-free access to the ebooks. As someone who is an avid collector of books, I fnd myself running out of room for storage. In addition, I travel a lot, and it's hard to lug my reference library with me. Today's e-reader options make the move to digital books a more viable way to grow my library. Having a variety of formats means I am not limited to a single device, and lifetime access means I don't have to worry about keeping track of where I've stored my files. Because the e-books are DRM-free, I can copy and paste when I'm compiling notes, and I can print pages when necessary. That's a winning combination in my mind! Overall, I was pleased with the BI conference. There were many more sessions that I couldn't attend, either because the room was full when I got there or there were multiple sessions running concurrently that I wanted to see. Fortunately, many of the sessions are accessible for viewing online at http://www.msteched.com/2010/NorthAmerica along with the TechEd sessions. You can spot the BI sessions by the yellow skyline on the title slide of the presentation as shown below. Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Large File Upload in SharePoint 2010

    - by Sahil Malik
    Ad:: SharePoint 2007 Training in .NET 3.5 technologies (more information). Okay this is a big BIG B-I-G problem. And with SP2010 it’s going to be more prominent, because atleast at the server side, SharePoint can support large files much much better than SharePoint 2007 ever did. The issue with very large files being uploaded through any browser based API are - Reliably transferring gigabyte or bigger files without breakages over a protocol like HTTP, which is better suited for tiny transfers like images and text. Not killing your browser because it has to load all that in memory Not killing your web server because All that you upload through HTTP post, first gets streamed into IIS Memory, w3wp.exe memory before the ENTIRE FILE finishes uploading .. before it is stored. Which means, You cannot show an accurate and live progress bar of the upload, IIS gives you no such accurate metric of an upload. All the counters it gives you are approximate. Your w3wp.exe eats up all server memory – 4GB of it, for a 4GB upload. A thread is kept busy for the entire duration of the upload, thereby greatly limiting your web server’s capability to serve newer requests. Kills effective load balancing. Not killing your content database because, As you are uploading a very large file, that large file gets written sequentially into the DB, and therefore for a very large file very severely impacts the database performance. I had put together another video showing RBS usage in SharePoint 2010. I talked about many practical ramifications of using RBS in SharePoint in that video. Note that enabling large file support will never ever be a point and click job, simply because there are too many questions one needs to ask, and too many things one needs to plan for. However, one part that will remain common across all large file upload scenarios, in SharePoint or outside of SharePoint is to do it efficiently while not killing the web server. In this video, I describe using the Telerik Silverlight Upload control with SharePoint 2010 to enable efficient large file uploads in SharePoint. Presenting .. The video Comment on the article ....

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