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  • Walmart's Mobile Self-Checkout

    - by David Dorf
    Reuters recently reported that Walmart was testing an iPhone-based self-checkout at a store near its headquarters.  Consumers scan items as they're placed in the physical basket, then the virtual basket is transferred to an existing self-checkout station where payment is tendered.  A very solid solution, but not exactly original. Before we go further, let's look at the possible cost savings for Walmart.  According to the article: Pushing more shoppers to scan their own items and make payments without the help of a cashier could save Wal-Mart millions of dollars, Chief Financial Officer Charles Holley said on March 7. The company spends about $12 million in cashier wages every second at its Walmart U.S. stores. Um, yeah. Using back-of-the-napkin math, I calculated Walmart's cashiers are making $157k per hour.  A more accurate statement would be saving $12M per year for each second saved on the average transaction time.  So if this self-checkout approach saves 2 seconds per transaction on average, Walmart would save $24M per year on labor.  Maybe.  Sometimes that savings will be used to do other tasks in the store, so it may not directly translate to less employees. When I saw this approach demonstrated in Sweden, there were a few differences, which may or may not be in Walmart's plans.  First, the consumers were identified based on their loyalty card.  In order to offset the inevitable shrink, retailers need to save on labor but also increase basket size, typically via in-aisle promotions.  As they scan items, retailers should target promos, and that's easier to do if you know some shopping history.  Last I checked, Walmart had no loyalty program. Second, at the self-checkout station consumers were randomly selected for an audit in which they must re-scan all the items just like you do at a typical self-checkout.  If you were found to be stealing, your ability to use the system can be revoked.  That's a tough one in the US, especially when the system goes wrong, either by mistake or by lying.  At least in my view, the Swedes are bit more trustworthy than the people of Walmart. So while I think the idea of mobile self-checkout has merit, perhaps its not right for Walmart.

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  • Contract Work - Lessons Learned

    - by samerpaul
    I thought I would write a post of a different nature today, but still relevant to the tech world. I do a lot of contract jobs myself and really enjoy it. It's nice to keep jumping from project to project, and not having to go to an office or keep regular hours, etc. I really enjoy it. I have learned a lot in the past few years of doing it (both from experience and from help given to me from others, and the internet) so I thought I'd share some of that knowledge/experience today.So here's my own personal "lesson's learned" that hopefully will help you if you find yourself doing contract work:Should I take the job?Ok, so this is the first step. Assuming you were given sufficient information about what they want, then you should really think about what you're capable of doing and whether or not you should take this job. Personally, my rule is, if I know it's possible, I'll say yes, even if I don't yet know how to do it. That's because the internet is such a great help, it would be rare to run into an issue that you can't figure out with some help. So if your clients are asking for something that you don't yet know how to program, but you know you can do it on the platform then go for it. How else are you going to learn?Use this rule with some limitation, however. If you're really lacking the expertise or foundation in something, then unless you have tons of time to complete the project, then I wouldn't say yes. For example, I haven't personally done any 3d/openGL programming yet so I wouldn't say yes to a project that extensively uses it. OK, so I want the job, but how much do I charge?This part can be tricky. There is no set formula really, but I have some tips for pricing that will hopefully give you a better idea on how to confidently ask your price and have them accept. Here are some personal guidelinesHow much time do you have to complete the project? If it's shorter than average, then charge more. You can even make a subtle note about this (or not so subtle if they still don't get it.) If it seems too short of a time (i.e. near impossible to complete), be sure to say that. It looks bad to promise a time that you can't keep--and it makes it less likely for them to return to you for work.Your Hourly rate: How long have you been working in that language? Do you have existing projects to back you up? Or previous contacts that can vouch for your work? Are there very few people with your particular skill set? All of these things will lend themselves to setting an hourly rate. I'd also try out a quick google search of what your line of work is, to see what the industry standard is at that point in time.I wouldn't price too low, because you want to make your time worth it. You also want them to feel like they're paying for quality work (assuming you can deliver it :) ). Finally, think about your client. If it's a small business, then don't price it too high if you want the job. If it's an enterprise (like a Fortune company), then don't be afraid to price higher. They have the budget for it.Fixed price: If they want a fixed price project, then you need to think about how many hours it will take you to complete it and multiply it by the hourly rate you set for yourself. Then, honestly, I would add 10-20% on top of that. Why? Because nothing ever works exactly how you want it to. There are lots of times that something "trivial" is way harder than it should be, or something that "should work" doesn't for hours and it eats away at your hourly rate. I can't count the number of times I encountered a logical bug that took away an entire's day work because debuggers don't help in those cases. By adding that padding in, it's still OK to have those days where you don't get as much done as you want. And another useful tip: Depending on your client, and the scope, you most likely want to set that you both sign off on a specification sheet before doing any work, and that any changes will result in a re-evaulation of the price. This is to help protect you from being handed a huge new addition to the project half-way in, without any extra payment.Scope of project: Finally, is it a huge project? Is it really small/fast? This affects how much your client will be willing to pay. If it sounds big, they will be willing to pay more for it. If it seems really small, then you won't be able to get away with a large asking price (as easily).Ok, I priced it, now what?So now that you have the price, you want to make sure it feels justified to your client. I never set a price before I can really think about everything. For example, if you're still in your introduction phase, and they want a price, don't give one! Just comment that you will send them a proposal sheet with all the features outlined, and a price for everything. You don't want to shout out a low number and then deliver something that is way higher. You also don't want to shock them with a big number before they feel like they are getting a great product.Make up a proposal document in a word editor. Personally, I leave the price till the very end. Why? Because by the time they reach the end, you've already discussed all the great features you plan to implement, and how it's the best product they'll ever use, etc etc...so your price comes off as a steal! If you hit them up front with a price, they will read through the document with a negative bias. Think about those commercials on TV. They always go on about their product, then at the end, ask "What would you pay for something like this? $100? $50? How about $20!!". This is not by accident.Scenario: I finished the job way earlier than expectedYou have two options then. You can either polish the hell out of the application, and even throw in a few bonus features (assuming they are in-line with the customer's needs) or you can sit and wait on it until you near your deadline. Why don't you want to turn it in too early? Because you should treat that extra time as a surplus. If you said it is going to take you 3 weeks, and it took you only 1, you have a surplus of 2 weeks. I personally don't want to let them know that I can do a 3 week project in 1 week. Why not? Because that may not always be the case! I may later have a 3 week project that takes all 3 weeks, but if I set a precedent of delivering super early, then the pressure is on for that longer project. It also makes it harder to quote longer times if you keep delivering too early.Feel free to deliver early, but again, don't do it too early. They may also wonder why they paid you for 3 weeks of work if you're done in 1. They may further wonder if the product sucks, or what is wrong with it, if it's done so early, etc.I would just polish the application. Everyone loves polish in their applications. The smallest details are what make an application go from "functional" to "fantastic". And since you are still delivering on time, then they are still going to be very happy with you.Scenario: It's taking way too long to finish this, and the deadline is nearing/here!So this is not a fun scenario to be in, but it'll happen. Sometimes the scope of the project gets out of hand. The best policy here is OPENNESS/HONESTY. Tell them that the project is taking longer than expected, and give a reasonable time for when you think you'll have it done. I typically explain it in a way that makes it sound like it isn't something that I did wrong, but it's just something about the nature of the project. This really goes for any scenario, to be honest. Just continue to stay open and communicative about your progress. This doesn't mean that you should email them every five minutes (unless they want you to), but it does mean that maybe every few days or once a week, give them an update on where you're at, and what's next. They'll be happy to know they are paying for progress, and it'll make it easier to ask for an extension when something goes wrong, because they know that you've been working on it all along.Final tips and thoughts:In general, contract work is really fun and rewarding. It's nice to learn new things all the time, as mandated by the project ,and to challenge yourself to do things you may not have done before. The key is to build a great relationship with your clients for future work, and for recommendations. I am always very honest with them and I never promise something I can't deliver. Again, under promise, over deliver!I hope this has proved helpful!Cheers,samerpaul

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  • Date Tracking in Oracle HRMS

    - by Manoj Madhusoodanan
    Update Date Track Modes To maintain employee data effectively Oracle HCM is using a mechanism called date tracking.The main motive behind the date track mode is to maintain past,present and future data effectively.The various update date track modes are: CORRECTION : Over writes the data. No history will maintain.UPDATE : Keeps the history and new change will effect as of effective dateUPDATE_CHANGE_INSERT : Inserts the record and preserves the futureUPDATE_OVERRIDE : Inserts the record and overrides the future Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Action: Created Employee # 22 on 01-JAN-2012 The record in PER_ALL_PEOPLE_F is as shown below. Effective Start Date Effective End Date Employee Number Marital Status Object Version Number 01-JAN-2012 31-DEC-4712 24 2 Action: Updated record in CORRECTION mode Effective Start Date Effective End Date Employee Number Marital Status Object Version Number 01-JAN-2012 31-DEC-4712 24 Single 3 Action: Updated record in UPDATE mode effective 01-JUN-2012 and Marital Status = Married Effective Start Date Effective End Date Employee Number Marital Status Object Version Number 01-JAN-2012 31-MAY-2012 24 Single 4 01-JUN-2012 31-DEC-4712 24 Married 5 Action: Updated record in UPDATE mode effective 01-SEP-2012 and Marital Status = Divorced Effective Start Date Effective End Date Employee Number Marital Status Object Version Number 01-JAN-2012 31-MAY-2012 24 Single 4 01-JUN-2012 31-AUG-2012 24 Married 6 01-SEP-2012 31-DEC-4712 24 Divorced 7 Action: Updated record in UPDATE_CHANGE_INSERT mode effective 01-MAR-2012 and Marital Status = Living Together Effective Start Date Effective End Date Employee Number Marital Status Object Version Number 01-JAN-2012 29-FEB-2012 24 Single 8 01-MAR-2012 31-MAY-2012 24 Living Together 9 01-JUN-2012 31-AUG-2012 24 Married 6 01-SEP-2012 31-DEC-4712 24 Divorced 7 Action: Updated record in UPDATE_OVERRIDE mode effective 01-AUG-2012 and Marital Status = Divorced Effective Start Date Effective End Date Employee Number Marital Status Object Version Number 01-JAN-2012 29-FEB-2012 24 Single 8 01-MAR-2012 31-MAY-2012 24 Living Together 9 01-JUN-2012 31-JUL-2012 24 Married 10 01-AUG-2012 31-DEC-4712 24 Divorced 11  Delete Date Track Modes The various delete date track modes are ZAP : wipes all recordsDELETE : Deletes  current recordFUTURE_CHANGE : Deletes current and future changes.DELETE_NEXT_CHANGE : Deletes next change Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Element Entry records are shown below. Effective Start Date Effective End Date Element Entry Id Object Version Number 01-JAN-2012 12-OCT-2012 129831 3 13-OCT-2012 19-OCT-2012 129831 5 20-OCT-2012 31-DEC-4712 129831 6 Action: Delete record in ZAP mode effective 14-JAN-2012 No rows Action: Delete record in DELETE mode effective 14-OCT-2012 Effective Start Date Effective End Date Element Entry Id Object Version Number 01-JAN-2012 12-OCT-2012 129831 3 13-OCT-2012 14-OCT-2012 129831 6 Action: Delete record in FUTURE_CHANGE mode effective 14-JAN-2012 Effective Start Date Effective End Date Element Entry Id Object Version Number 01-JAN-2012 31-DEC-4712 129831 4 Action: Delete record in NEXT_CHANGE mode effective 14-JAN-2012 Effective Start Date Effective End Date Element Entry Id Object Version Number 01-JAN-2012 19-OCT-2012 129831 4 20-OCT-2012 31-DEC-4712 129831 6

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  • multithreading problem with Nvidia PhysX

    - by xcrypt
    I'm having a multithreading problem with Nvidia PhysX. the SDK requires that you call Simulate() (starts computing new physics positions within a new thread) and FetchResults(waits 'till the physics computations are done). Inbetween Simulate() and FetchResults() you may not 'compute new physics' It is proposed (in a sample) that we create a game loop as such: Logic (you may calculate physics here and other stuff) Render + Simulate() at start of Render call and FetchResults at end of Render() call However, this has given me various little errors that stack up: since you actually render the scene that was computed in the previous iteration in the game loop. I wonder if there's a way around this? I've been trying and trying, but I can't think of a solution...

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  • How do I properly use multithreading with Nvidia PhysX?

    - by xcrypt
    I'm having a multithreading problem with Nvidia PhysX. the SDK requires that you call Simulate() (starts computing new physics positions within a new thread) and FetchResults() (waits 'till the physics computations are done). Inbetween Simulate() and FetchResults() you may not "compute new physics". It is proposed (in a sample) that we create a game loop as such: Logic (you may calculate physics here and other stuff) Render + Simulate() at start of Render call and FetchResults at end of Render() call However, this has given me various little errors that stack up: since you actually render the scene that was computed in the previous iteration in the game loop. Does anyone have a solution to this?

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  • Parallel MSBuild FTW - Build faster in parallel

    - by deadlydog
    Hey everyone, I just discovered this great post yesterday that shows how to have msbuild build projects in parallel Basically all you need to do is pass the switches “/m:[NumOfCPUsToUse] /p:BuildInParallel=true” into MSBuild. Example to use 4 cores/processes (If you just pass in “/m” it will use all CPU cores): MSBuild /m:4 /p:BuildInParallel=true "C:\dev\Client.sln" Obviously this trick will only be useful on PCs with multi-core CPUs (which we should all have by now) and solutions with multiple projects; So there’s no point using it for solutions that only contain one project.  Also, testing shows that using multiple processes does not speed up Team Foundation Database deployments either in case you’re curious Also, I found that if I didn’t explicitly use “/p:BuildInParallel=true” I would get many build errors (even though the MSDN documentation says that it is true by default). The poster boasts compile time improvements up to 59%, but the performance boost you see will vary depending on the solution and its project dependencies.  I tested with building a solution at my office, and here are my results (runs are in seconds): # of Processes 1st Run 2nd Run 3rd Run Avg Performance 1 192 195 200 195.67 100% 2 155 156 156 155.67 79.56% 4 146 149 146 147.00 75.13% 8 136 136 138 136.67 69.85%   So I updated all of our build scripts to build using 2 cores (~20% speed boost), since that gives us the biggest bang for our buck on our solution without bogging down a machine, and developers may sometimes compile more than 1 solution at a time.  I’ve put the any-PC-safe batch script code at the bottom of this post. The poster also has a follow-up post showing how to add a button and keyboard shortcut to the Visual Studio IDE to have VS build in parallel as well (so you don’t have to use a build script); if you do this make sure you use the .Net 4.0 MSBuild, not the 3.5 one that he shows in the screenshot.  While this did work for me, I found it left an MSBuild.exe process always hanging around afterwards for some reason, so watch out (batch file doesn’t have this problem though).  Also, you do get build output, but it may not be the same that you’re used to, and it doesn’t say “Build succeeded” in the status bar when completed, so I chose to not make this my default Visual Studio build option, but you may still want to. Happy building! ------------------------------------------------------------------------------------- :: Calculate how many Processes to use to do the build. SET NumberOfProcessesToUseForBuild=1  SET BuildInParallel=false if %NUMBER_OF_PROCESSORS% GTR 2 (                 SET NumberOfProcessesToUseForBuild=2                 SET BuildInParallel=true ) MSBuild /maxcpucount:%NumberOfProcessesToUseForBuild% /p:BuildInParallel=%BuildInParallel% "C:\dev\Client.sln"

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  • How to fix an annoying ReSharper &ndash; NuGet error

    - by terje
    Originally posted on: http://geekswithblogs.net/terje/archive/2013/10/30/how-to-fix-an-annoying-resharper-ndash-nuget-error.aspxUsing NuGet in Visual Studio together with ReSharper may sometimes lead you into an annoying error where ReSharper indicates your code has an error, but the solution builds just fine. This may happen if you have a set of NuGet packages, and you either just restore them, or delete them on disk and then restore again.  Your code ends up looking like this, note the red missing functions, which comes from the Moq library - which is downloaded from NuGet:   while the Build is still fine, it compiles without any errors: This stackoverflow question gives some different approaches to solve this, but my experience have been that the Resharper Suspend-Resume trick most often solves the issue: In Visual Studio:  Go to Tools/Options/Resharper Press Suspend: When this is done the error markers disappear, since ReSharper now is inactive. Then just press Resume again: This has been submitted to Jetbrains support, ticket here: http://resharper-support.jetbrains.com/requests/3882) , if you want to follow it.

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  • Oracle Solaris 11 Developer Webinar Series

    - by nospam(at)example.com (Joerg Moellenkamp)
    Starting March 27th a number of events called "Oracle Solaris 11 Developer Webinar Series" (that said, i think they are not only interesting for developers, but for admins as well that support admins in their job) will take place by WebEx/Phone: March 27th: Modern Software Packaging for Enterprise Developers April 10th: Simplify Your Development Environment with Zones, ZFS & More April 24th: Managing Application Services ? Using SMF Manifests in Solaris 11 May 8th: Optimize Your Applications on Oracle Solaris 11: The DTrace Advantage May 22nd: Maximize Application Performance and Reliability on Oracle Solaris 11 June 5th: Writing Oracle Solaris 11 Device Drivers All events start at 9am Pacific Daylight Time (Should be 18:00 in Germany, 17:00 in UK, 01:00 in Tokyo). Of course the events are for free (before someone asks) and available for anyone who signs up. The chat is staffed with Solaris 11 Engineering Experts sitting in to answer questions. And most important: Mostly technical content and the events will be recorded.

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  • HTG Explains: How the SmartScreen Filter Works in Windows 8

    - by Chris Hoffman
    Windows 8 includes a SmartScreen filter that prevents unknown and malicious programs from running. SmartScreen is part of Internet Explorer 8 and 9 – with Windows 8, it’s now integrated into the operating system. SmartScreen is a useful security feature that will help prevent bad applications from running, but it may occasionally prevent a legitimate application from running. SmartScreen reports some information to Microsoft, so it may have some privacy implications. HTG Explains: Is ReadyBoost Worth Using? HTG Explains: What The Windows Event Viewer Is and How You Can Use It HTG Explains: How Windows Uses The Task Scheduler for System Tasks

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  • Of transactions and Mongo

    - by Nuri Halperin
    Originally posted on: http://geekswithblogs.net/nuri/archive/2014/05/20/of-transactions-and-mongo-again.aspxWhat's the first thing you hear about NoSQL databases? That they lose your data? That there's no transactions? No joins? No hope for "real" applications? Well, you *should* be wondering whether a certain of database is the right one for your job. But if you do so, you should be wondering that about "traditional" databases as well! In the spirit of exploration let's take a look at a common challenge: You are a bank. You have customers with accounts. Customer A wants to pay B. You want to allow that only if A can cover the amount being transferred. Let's looks at the problem without any context of any database engine in mind. What would you do? How would you ensure that the amount transfer is done "properly"? Would you prevent a "transaction" from taking place unless A can cover the amount? There are several options: Prevent any change to A's account while the transfer is taking place. That boils down to locking. Apply the change, and allow A's balance to go below zero. Charge person A some interest on the negative balance. Not friendly, but certainly a choice. Don't do either. Options 1 and 2 are difficult to attain in the NoSQL world. Mongo won't save you headaches here either. Option 3 looks a bit harsh. But here's where this can go: ledger. See, and account doesn't need to be represented by a single row in a table of all accounts with only the current balance on it. More often than not, accounting systems use ledgers. And entries in ledgers - as it turns out – don't actually get updated. Once a ledger entry is written, it is not removed or altered. A transaction is represented by an entry in the ledger stating and amount withdrawn from A's account and an entry in the ledger stating an addition of said amount to B's account. For sake of space-saving, that entry in the ledger can happen using one entry. Think {Timestamp, FromAccountId, ToAccountId, Amount}. The implication of the original question – "how do you enforce non-negative balance rule" then boils down to: Insert entry in ledger Run validation of recent entries Insert reverse entry to roll back transaction if validation failed. What is validation? Sum up the transactions that A's account has (all deposits and debits), and ensure the balance is positive. For sake of efficiency, one can roll up transactions and "close the book" on transactions with a pseudo entry stating balance as of midnight or something. This lets you avoid doing math on the fly on too many transactions. You simply run from the latest "approved balance" marker to date. But that's an optimization, and premature optimizations are the root of (some? most?) evil.. Back to some nagging questions though: "But mongo is only eventually consistent!" Well, yes, kind of. It's not actually true that Mongo has not transactions. It would be more descriptive to say that Mongo's transaction scope is a single document in a single collection. A write to a Mongo document happens completely or not at all. So although it is true that you can't update more than one documents "at the same time" under a "transaction" umbrella as an atomic update, it is NOT true that there' is no isolation. So a competition between two concurrent updates is completely coherent and the writes will be serialized. They will not scribble on the same document at the same time. In our case - in choosing a ledger approach - we're not even trying to "update" a document, we're simply adding a document to a collection. So there goes the "no transaction" issue. Now let's turn our attention to consistency. What you should know about mongo is that at any given moment, only on member of a replica set is writable. This means that the writable instance in a set of replicated instances always has "the truth". There could be a replication lag such that a reader going to one of the replicas still sees "old" state of a collection or document. But in our ledger case, things fall nicely into place: Run your validation against the writable instance. It is guaranteed to have a ledger either with (after) or without (before) the ledger entry got written. No funky states. Again, the ledger writing *adds* a document, so there's no inconsistent document state to be had either way. Next, we might worry about data loss. Here, mongo offers several write-concerns. Write-concern in Mongo is a mode that marshals how uptight you want the db engine to be about actually persisting a document write to disk before it reports to the application that it is "done". The most volatile, is to say you don't care. In that case, mongo would just accept your write command and say back "thanks" with no guarantee of persistence. If the server loses power at the wrong moment, it may have said "ok" but actually no written the data to disk. That's kind of bad. Don't do that with data you care about. It may be good for votes on a pole regarding how cute a furry animal is, but not so good for business. There are several other write-concerns varying from flushing the write to the disk of the writable instance, flushing to disk on several members of the replica set, a majority of the replica set or all of the members of a replica set. The former choice is the quickest, as no network coordination is required besides the main writable instance. The others impose extra network and time cost. Depending on your tolerance for latency and read-lag, you will face a choice of what works for you. It's really important to understand that no data loss occurs once a document is flushed to an instance. The record is on disk at that point. From that point on, backup strategies and disaster recovery are your worry, not loss of power to the writable machine. This scenario is not different from a relational database at that point. Where does this leave us? Oh, yes. Eventual consistency. By now, we ensured that the "source of truth" instance has the correct data, persisted and coherent. But because of lag, the app may have gone to the writable instance, performed the update and then gone to a replica and looked at the ledger there before the transaction replicated. Here are 2 options to deal with this. Similar to write concerns, mongo support read preferences. An app may choose to read only from the writable instance. This is not an awesome choice to make for every ready, because it just burdens the one instance, and doesn't make use of the other read-only servers. But this choice can be made on a query by query basis. So for the app that our person A is using, we can have person A issue the transfer command to B, and then if that same app is going to immediately as "are we there yet?" we'll query that same writable instance. But B and anyone else in the world can just chill and read from the read-only instance. They have no basis to expect that the ledger has just been written to. So as far as they know, the transaction hasn't happened until they see it appear later. We can further relax the demand by creating application UI that reacts to a write command with "thank you, we will post it shortly" instead of "thank you, we just did everything and here's the new balance". This is a very powerful thing. UI design for highly scalable systems can't insist that the all databases be locked just to paint an "all done" on screen. People understand. They were trained by many online businesses already that your placing of an order does not mean that your product is already outside your door waiting (yes, I know, large retailers are working on it... but were' not there yet). The second thing we can do, is add some artificial delay to a transaction's visibility on the ledger. The way that works is simply adding some logic such that the query against the ledger never nets a transaction for customers newer than say 15 minutes and who's validation flag is not set. This buys us time 2 ways: Replication can catch up to all instances by then, and validation rules can run and determine if this transaction should be "negated" with a compensating transaction. In case we do need to "roll back" the transaction, the backend system can place the timestamp of the compensating transaction at the exact same time or 1ms after the original one. Effectively, once A or B visits their ledger, both transactions would be visible and the overall balance "as of now" would reflect no change.  The 2 transactions (attempted/ reverted) would be visible , since we do actually account for the attempt. Hold on a second. There's a hole in the story: what if several transfers from A to some accounts are registered, and 2 independent validators attempt to compute the balance concurrently? Is there a chance that both would conclude non-sufficient-funds even though rolling back transaction 100 would free up enough for transaction 117 (some random later transaction)? Yes. there is that chance. But the integrity of the business rule is not compromised, since the prime rule is don't dispense money you don't have. To minimize or eliminate this scenario, we can also assign a single validation process per origin account. This may seem non-scalable, but it can easily be done as a "sharded" distribution. Say we have 11 validation threads (or processing nodes etc.). We divide the account number space such that each validator is exclusively responsible for a certain range of account numbers. Sounds cunningly similar to Mongo's sharding strategy, doesn't it? Each validator then works in isolation. More capacity needed? Chop the account space into more chunks. So where  are we now with the nagging questions? "No joins": Huh? What are those for? "No transactions": You mean no cross-collection and no cross-document transactions? Granted - but don't always need them either. "No hope for real applications": well... There are more issues and edge cases to slog through, I'm sure. But hopefully this gives you some ideas of how to solve common problems without distributed locking and relational databases. But then again, you can choose relational databases if they suit your problem.

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  • Cant install wine1.5 13.04

    - by Drew S
    So I tried to install wine 1.5 a few times, I got 1.4 installed, and 1.6 installed oddly enough, I completely removed and purged all wine and still nothing. I installed ia32-lib and still nothing, tried installing from synaptic, ubuntu software center, and apt-get method. I get this error from apt-get in the terminal Reading package lists... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help resolve the situation: The following packages have unmet dependencies: wine1.5 : Depends: wine1.6 but it is not going to be installed E: Unable to correct problems, you have held broken packages. The particular windows program I want to install is confirmed working in 1.5(have it working on laptop)

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  • Architects, Leadership, and Influence

    - by Bob Rhubart
    Technical expertise is a given for architects. In addition to solid development experience, extensive knowledge of technical trends, tools, standards, and methodolgies (not to mention business accumen) provides the foundation for the decisions the architect must make in the effort to get all the pieces to work together. But even superior technical chops can't overcome a lack of leadership. Leadership is about influence: the ability to effectively communicate — to sell your ideas and defend your decisions in a manner that affects the decisions of the people around you. Leadership and influence are especially important in situations in which the architect may not have the authority to simply tell people what to do. And even when the architect has that kind of authority, influential leadership can mean the difference between gaining real buy-in and support from colleagues and stakeholders, and settling for their grudging acceptance (or worse). Guess which outcome is likely to produce the best results. In a previous post I presented some examples of the kind of criticism that is leveled at architects, a great deal of which can be attributed to a lack of leadership and influence on the part of the targets of that criticism. So it was serendipitous that I recently ran across a post on the Harvard Business Review blog written by Chris Musselwhite and Tammie Plouffe. That post, When Your Influence Is Ineffective, includes this: [I]nfluence becomes ineffective when individuals become so focused on the desired outcome that they fail to fully consider the situation. While the influencer may still gain the short-term desired outcome, he or she can do long-term damage to personal effectiveness and the organization, as it creates an atmosphere of distrust where people stop listening, and the potential for innovation or progress is diminished. The need to "see the big picture" is a grossly reductive assesement of the architect's responsibilities — but that doesn't mean it's not true. That big picture perspective must encompass both the technological elements of the architecture and the elements responsible for implementing those technologies in compliance with the prescribed architecture. Technologies may be tempermental, but they don't have personalities or egos, and they are unlikely to carry a grudge — not yet, anyway (Hello, Skynet!).  Effective leadership and the ability to influence people can help to ensure that all the pieces fit and that they work together, today and tomorrow.

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  • how to change gtk3 color scheme on ubuntu 13.04

    - by Michael87
    I am making the transition from windows 7 to ubuntu 13.04. I have ran ubuntu twice on my laptop and switched back to windows 7 namely becuase the orange and gray colors of ubuntu is just ugly. I know how to change ambiance to radiance but the gtk colors themselves SHOULD be customizable. I managed to do it once with 12.04 using kde's color manager but the thing wigged out on me. So please. is there a way to change 13.04's color scheme without downloading some theme that may or may not work? thank you.

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  • Will many links to the same page without nofollow penalize the host site in the search engine rankings?

    - by Evgeny
    May be a silly question, but I'll give it a shot :). On my forum app I would like to allow users with sufficiently high reputation display links to their home pages under every post - without the nofollow attribute (while lower rep users will have the nofollow) I am happy to help the site contributors improve rankings of their own, but not sure if this can actually deteriorate the rank of the host (the site that hosts those links) - as potentially the same link to the user's home page may be peppered in the pages of the host. What do you think? Thanks.

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  • Too early to apply for post-graduation jobs?

    - by Rob Lourens
    I graduate in May 2012. I'm on an internship with one company right now that will probably make me an offer in August, but I will only have a couple weeks to take or leave it. I'm not sure whether I'll want to accept it- it will depend on the specifics. So I plan to apply for other jobs to see if I can get another offer, but would it be too early to be applying over the next few weeks when I wouldn't start until next May at least? I hate to turn down an offer having nothing else lined up. I'm a software engineer at one large software company and I would apply for jobs at other large software companies. I assume a smaller company would work on a much shorter hiring schedule, but maybe large companies wouldn't mind hiring 8-9 months in advance? I also hate to start applying any earlier than I have to- I know I'll only have more experience and be more employable with time.

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  • The Uganda .NET Usergroup meeting for January 2011 - a look back.

    - by Malisa L. Ncube
    We had a very interesting meeting on Friday 28th last week. We had 10 attendees and two speakers. The first topic presented was Cloud Computing, presented by Allan Rwakatungu @arwakatungu who works with MTN Uganda. He gave a very brilliant outline of how Cloud computing and service oriented applications had begun changing the platform for operating business and the costs it saves because of scalability and elasticity. He went on to demonstrate the steps you would take if you are beginning a new Windows Azure project. He explained the history and evolution of the Windows Azure, SQL Azure and cloud services offered by Amazon and google.com. The attendees had many questions to ask (obviously), but they were all answered very well. We once again thank Allan, for taking time to prepare the presentation and demonstrating for us. We recorded a video on the entire presentation and after doing some editing we will publish it. One wish which was echoed by most members was that Microsoft should open the cloud services and development for Africa. Microsoft currently does not even have servers here in Africa and so far, that does not put African developers in the same platform as other developers in other continents. Now is the time considering the improvements in network speeds and joining of the Seacom network and broadband.   I presented on Parallelism and Multithreading using .NET 4.0, I also gave some details on the language changes in C# 5.0 and the async keyword and the TaskEx class. I explained the Task, Scheduling of parallel tasks and demonstrated problems that may arise from using parallelism inappropriately. I also demonstrated the performance improvements that may be achieved by taking advantage of multi-core processors. You may download the presentation on Parallelism and Multi-threading from here. The resolution of the meeting was that we should meet more than once a month and begin other activities which should be more fun. e.g. Geek Dinner, Geek Beer or CodeCamp. Based on that we all agreed we shall have a mid-month meeting starting from February. Cheers folks! del.icio.us Tags: .net,usergroup,cloud computing,parallelism,multi-threading

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  • What are some concepts people should understand before programming "big" projects?

    - by Abafei
    A person new to programming may be able to make a good small program. However, when starting to work on anything bigger than a small (think 1 C source file or Python module) program, there are some general concepts which become much more important when working on "big" (think many Python modules or C files) programs; one example is modularity, another is having a set aim. Some of these may be obvious to people who went to school to learn programming; however, people like me who did not go to programming classes sometimes have to learn these things from experience, possibly creating failed projects in the meantime. ================================================== Please explain what the concept is, and why the concept becomes more important for big programs than by small programs. Please give only 1 concept per answer.

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  • Need help installing Wine onto Ubuntu 12.10x64

    - by user106241
    I have tried to install wine through the software center and terminal and I get this error. chris@ubuntu:~$ sudo apt-get install wine1.5 [sudo] password for chris: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wine1.5 : Depends: wine1.5-i386 (= 1.5.16-0ubuntu1) but it is not installable Recommends: gnome-exe-thumbnailer but it is not going to be installed or kde-runtime but it is not going to be installed Recommends: ttf-droid Recommends: ttf-mscorefonts-installer but it is not going to be installed Recommends: ttf-umefont but it is not going to be installed Recommends: ttf-unfonts-core but it is not going to be installed Recommends: winbind but it is not going to be installed Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages.

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  • What are the so-called "levels" of understanding multithreading?

    - by Dan Tao
    I seem to remember reading somewhere some list of 4 "levels" of understanding multithreading. This may have been in a formal publication, or it may have been in an extremely informal context (even like in a Stack Overflow question, for example). Unfortunately I don't remember who referred to them or precisely what they were. I seem to recall that they were roughly like: Total ignorance Awareness mixed with incompetence Relative competence mixed with fear True understanding My intention is to refer to these levels in a blog post I'm writing, with a reference; but I can't for the life of me remember where I first encountered this list. Brief Google searches have proved unfruitful.

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  • problem in installing wireshark on ubuntu 12.04

    - by iqbal
    i tried to install wireshark on ubuntu 12.04 but when i enter the cod the message is whone to me is iqbal@iqbal-HP-ProBook-4530s:~$ sudo apt-get install wireshark Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wireshark : Depends: wireshark-common (= 1.11.4+svn20140420104827~d0489f2a-0ubuntu1~precise1~ppa0) but it is not going to be installed E: Unable to correct problems, you have held broken packages so how can i install wireshark on ubuntu 12.04 if any one can please tell me thanks

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  • Exalogic 2.0.1 Tea Break Snippets - Creating and using Distribution Groups

    - by The Old Toxophilist
    By default running your Exalogic in a Virtual provides you with, what to Cloud Users, is a single large resource and they can just create vServers and not care about how they are laid down on the the underlying infrastructure. All the Cloud Users will know is that they can create vServers. For example if we have a Quarter Rack (8 Nodes) and our Cloud User creates 8 vServers those 8 vServers may run on 8 distinct nodes or may all run on the same node. Although in many cases we, as Cloud Users, may not be to worried how the Virtualisation Algorithm decides where to place our vServers there are cases where it is extremely important that vServers run on distinct physical compute nodes. For example if we have a Weblogic Cluster we will want the Servers with in the cluster to run on distinct physical node to cover for the situation where one physical node is lost. To achieve this the Exalogic Virtualised implementation provides Distribution Groups that define and anti-aliasing policy that the underlying Virtualisation Algorithm will take into account when placing vServers. It should be noted that Distribution Groups must be created before you create vServers because a vServer can only be added to a Distribution Group at creation time. Creating A Distribution Group To create a Distribution Groups we will first need to select the Account in which we want the Distribution Group to be created. Once we have selected the account we will see the Interface update and Account specific Actions will be displayed within the Action Panes. From the Action pane (or Right-Click on the Account) select the "Create Distribution Group" action. This will initiate the create wizard as follows. Distribution Group Details Within the first Step of the Wizard we can specify the name of the distribution group and this should be unique. In addition we can provide a detailed description of the group. Distribution Group Configuration The second step of the configuration wizard allows you to specify the number of elements that are required within this group and will specify a maximum of the number of nodes within you Exalogic. At this point it is always better to specify a group with spare capacity allowing for future expansion. As vServers are added to group the available slots decrease. Summary Finally the last step of the wizard display a summary of the information entered.

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  • When a problem is resolved

    - by Rob Farley
    This month’s T-SQL Tuesday is hosted by Jen McCown, and she’s picked the topic of Resolutions. It’s a new year, and she’s thinking about what people have resolved to do this year. Unfortunately, I’ve never really done resolutions like that. I see too many people resolve to quit smoking, or lose weight, or whatever, and fail miserably. I’m not saying I don’t set goals, but it’s not a thing for New Year. The obvious joke is “1920x1080” as a resolution, but I’m not going there. I think Resolving is a strange word. It makes it sound like I’m having to solve a problem a second time, when actually, it’s more along the lines of solving a problem well enough for it to count as finished. If something has been resolved, a solution has been provided. There is a resolution, through the provision of a solution. It’s a strangeness of English. When I look up the word resolution at dictionary.com, it has 12 options, including “settling of a problem”. There’s a finality about resolution. If you resolve to do something, you’re saying “Yes. This is a done thing. I’m resolving to do it, which means that it may as well be complete already.” I like to think I resolve problems, rather than just solving them. I want my solving to be final and complete. If I tune a query, I don’t want to find that I’m back in there, re-tuning it at some point. Strangely, if I re-solve a problem, that implies that I didn’t resolve it in the first place. I only solved it. Temporarily. We “data-folk” live in a world where the most common answer is “It depends.” Frustratingly, the thing an answer depends on may still be changing in the system in question. That probably means that any solution that is put in place may need reinvestigating at some point later. So do I resolve things? Yes. Am I Chuck Norris, and solve things so well the world would break first? No. Do these two claims happily sit beside each other? No, unfortunately not. But I happily take responsibility for things, and let my clients depend on me to see it through. As far as they are concerned, it is resolved. And so I resolve to keep resolving, right through 2011.

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  • eDelivery (Delivery Cloud) Housekeeping - removal of obsolete EPM products

    - by THE
    You may have noticed that Weblogic Server (WLS) 9.2.X and WLS 10.0.X releases have been removed from the Oracle Software Delivery Cloud. The Delivery Team has been asked to remove or update any product pack or product that embeds WLS 10.3.2 or earlier versions. This is consistent with general Oracle practice of removing old product versions from public distribution systems, and encourages customer usage and adoption of newer product releases such as WLS 10.3.3 or newer.  For the convenience of existing supported customers, a media request SR on My Oracle Support can be entered to obtain any removed media.  Information on how to open such an SR can be found on  MOS Doc ID 1071023.1 . OTN will also be reviewed and similar modifications may potentially be done.  The following media packs will be removed from E-Delivery this week, as of the above reason. Hyperion 9.3.1 Hyperion 9.2.1 Hyperion Pre-system 9 EPM 11.1.1.3 EPM 11.1.1.4

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  • Samba installation failed on ubuntu 12.10

    - by Ayyaz
    I was trying to install samba to access shared printer on windows pc connected via office network, following response came out from terminal. please guide me how to install Samba or any other alternative. crm@crm-HP-G62-Notebook-PC:~$ sudo apt-get install samba [sudo] password for crm: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: samba : Depends: samba-common (= 2:3.6.6-3ubuntu4) but 2:3.6.6-3ubuntu5 is to be installed Depends: libwbclient0 (= 2:3.6.6-3ubuntu4) but 2:3.6.6-3ubuntu5 is to be installed Recommends: tdb-tools but it is not going to be installed E: Unable to correct problems, you have held broken packages. crm@crm-HP-G62-Notebook-PC:~$

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