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  • Career guidance/advice for Junior-level Software Engineer [closed]

    - by John Do
    I have quite a few questions on my mind, so please bare with me. Please don't feel obligated to answer all of them, any as you choose will do. I'd appreciate if you could share some insight on any of these. Before I begin, some context: I currently have almost two years of professional experience as a Software Engineer, mainly developing software in Java. At this point, I feel that I have reached the peak in my career growth at the current company I am at and therefore I am looking for a new job, ideally again, as a Software Engineer. I have been interviewing for the past few months casually but have not had luck with companies I have a passion for. So, in no particular order - 1) In general, what are your thoughts on having graduate degrees in CS / Software Engineering. How much does it influence a salary increase, and do you think it's beneficial when working on real-world problems? I get the sense that a graduate degree in the field is trivial unless you really have a passion for research. 2) In general, in professional practice, how often had you have to write your own data structures and "complex" algorithms from scratch? In my own work, I have found myself relying mainly on third-party frameworks and the Java standard library to implement solutions as per business requirements. What are your thoughts on this? 3) In terms of resume, I feel the most ambivalent here. I want to be able to "blemish" my resume to a certain extent so that it stands out from others', but at the same time I do not want to over-exagerate my abilities. How do you strike a balance here? For example: I say that I am proficient in Java with data structures and algorithms. This is obviously a subjective and relative statement. I've taken the classes in my undergrad, and I've applied it in my work experience. What I feel as "prociency" can be seen as junior-level to others. How do you know what to say? Most of the time, recruiters (with no technical background) will be looking for keywords that stand out. This leads me to my next question (4). 4) Just from interviewing for the past few months (and getting plenty of rejections), I've come to realize that I may not be as proficient in data structures and algorithms as I thought I was. Do you think it's a good idea to remove the "proficient in java/data structure and algorithms"? I feel that being too hoenst on the resume will impede me from scoring opportunities to even have an interview with top-notch companies. What are your thoughts? 5) What is the absolute "must-have" knowledge going into a technical interview? I've been practicing several algorithmic and data sturcture problems now, and I feel that my abilities to solve arbitrary problems efficiently has not gotten significantly better. Do you think these abilities are something innate - it's either you have in you, or you don't? How can you teach yourself to learn, if you will? 6) How easy is it to go from industry/function to the next? I work mainly with backend technologies and I'm now interested in working with the frontend, i.e javascript,jquery,php or even mobile development. In your own experience, how did you not get pidgeon holed in your career? I feel that the choices you make now ultimately decide your future. As cliche as it sounds, I think it may be true. Here's what I mean: you've worked mainly as a backend engineer, people are interested in you doing the same thing since you've already accumulated experience in that function. How do get experience in a new function if people won't accept you because you don't already have it? It's a catch 22, you see... Are side projects the only real way to help you move from one function to another that you're truly interested in? For example: I could start writing my own mobile applications, even though I've worked mainly on the backend. Thanks so much for the long read. As a relatively new engineer to the real world, I am very humble and would like those who are experienced to shed some light. Thank you so much.

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  • SQL SERVER – Weekly Series – Memory Lane – #004

    - by pinaldave
    Here is the list of curetted articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2006 Auto Generate Script to Delete Deprecated Fields in Current Database In early career everytime I have to drop a column, I had hard time doing it because I was scared what if that column was needed somewhere in the code. Due to this fear I never dropped any column. I just renamed the column. If the column which I renamed was needed afterwards it was very easy to rename it back again. However, it is not recommended to keep the deleted column renamed in the database. At every interval I used to drop the columns which was prefixed with specific word. This script is 6 years old but still works. Give it a look, I am open for improvements. 2007 Shrinking Truncate Log File – Log Full – Part 2 Shrinking database or mdf file is indeed bad thing and it creates lots of problems. However, once in a while there is legit requirement to shrink the log file – a very rare one. In the rare occasion shrinking or truncating the log file may be the only solution. However, one should make sure to take backup before and after the truncate or shrink as in case of a disaster they can be very useful. Remember that truncating log file will break the log chain and while restore it can create major issue. Anyway, use this feature with caution. 2008 Simple Use of Cursor to Print All Stored Procedures of Database Including Schema This is a very interesting requirement I used to face in my early career days, I needed to print all the Stored procedures of my database. Interesting enough I had written a cursor to do so. Today when I look back at this stored procedure, I believe there will be a much cleaner way to do the same task, however, I still use this SP quite often when I have to document all the stored procedures of my database. Interesting Observation about Order of Resultset without ORDER BY In industry many developers avoid using ORDER BY clause to display the result in particular order thinking that Index is enforcing the order. In this interesting example, I demonstrate that without using ORDER BY, same table and similar query can return different results. Query optimizer always returns results using any method which is optimized for performance. The learning is There is no order unless ORDER BY is used. 2009 Size of Index Table – A Puzzle to Find Index Size for Each Index on Table I asked this puzzle earlier where I asked how to find the Index size for each of the tables. The puzzle was very well received and lots of interesting answers were received. To answer this question I have written following blog posts. I suggest this weekend you try to solve this problem and see if you can come up with a better solution. If not, well here are the solutions. Solution 1 | Solution 2 | Solution 3 Understanding Table Hints with Examples Hints are options and strong suggestions specified for enforcement by the SQL Server query processor on DML statements. The hints override any execution plan the query optimizer might select for a query. The SQL Server Query optimizer is a very smart tool and it makes a better selection of execution plan. Suggesting hints to the Query Optimizer should be attempted when absolutely necessary and by experienced developers who know exactly what they are doing (or in development as a way to experiment and learn). Interesting Observation – TOP 100 PERCENT and ORDER BY I have seen developers and DBAs using TOP very causally when they have to use the ORDER BY clause. Theoretically, there is no need of ORDER BY in the view at all. All the ordering should be done outside the view and view should just have the SELECT statement in it. It was quite common that to save this extra typing by including ordering inside of the view. At several instances developers want a complete resultset and for the same they include TOP 100 PERCENT along with ORDER BY, assuming that this will simulate the SELECT statement with ORDER BY. 2010 SQLPASS Nov 8-11, 2010-Seattle – An Alternative Look at Experience In year 2010 I attended most prestigious SQL Server event SQLPASS between Nov 8-11, 2010 at Seattle. I have only one expression for the event - Best Summit Ever. Instead of writing about my usual routine or the event, I wrote about the interesting things I did and how I felt about it! When I go back and read it, I feel that this is the best event I attended in year 2010. Change Database Access to Single User Mode Using SSMS Image says all. 2011 SQL Server 2012 has introduced new analytic functions. These functions were long awaited and I am glad that they are now here. Before when any of this function was needed, people used to write long T-SQL code to simulate these functions. But now there’s no need of doing so. Having available native function also helps performance as well readability. Function SQLAuthority MSDN CUME_DIST CUME_DIST CUME_DIST FIRST_VALUE FIRST_VALUE FIRST_VALUE LAST_VALUE LAST_VALUE LAST_VALUE LEAD LEAD LEAD LAG LAG LAG PERCENTILE_CONT PERCENTILE_CONT PERCENTILE_CONT PERCENTILE_DISC PERCENTILE_DISC PERCENTILE_DISC PERCENT_RANK PERCENT_RANK PERCENT_RANK Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • Silverlight Cream Monday WP7 App Review # 2

    - by Dave Campbell
    Today's Review (alphabetic order): GooNews, Grocery Shopping List, Need for Speed, SurfCube, and United Nations News. I'm a day late if these are going to be 'Monday' posts, but there are lots of apps, lots of goodness, and lots of email, so I might try to do 2 a week, we'll see. So once again I've got a small review of 5 apps that are either on my phone or have been. Disclaimers at the end. In this Issue:   GooNews is a very cool app from Shawn Wildermuth (AgiliTrain). I don't know if he uses this as a demo during his instruction, but it definitely serves a purpose... wanna pick up the top news items from Google on a never-ending basis? ... this is it. You can add your own keyword searches, and send stories to InstaPaper or share via email. I like this because it brings me the news quickly and updated, and works great. GooNews is by AgiliTrain and is Free This was a request by the author, and actually surprised me. I'm a big one for lists, but I would have just done a OneNote list to SkyDrive and to my phone. This app is a lot more than that, but will take you some setup to make it be 'yours'. For obvious reasons, there are no unit prices on things, so you have to set that up to get some idea of the cost of what you're shopping for. But if you do that, you'll get a nice total. Lots of thought went into the various categories and you can add your own. There's a bit of animation on the category selection that's nice. He seems to have covered all the bases necessary to use this, even shopping 'plans' that can be saved, and emailing of lists. As I said, I'm more of a raw list person, but if you take the time to set this up, it should work very nicely for you. Grocery Shopping List is by Grocery Shopper and is $0.99 ($1.99 after Feb 1) with a free trial. This was my 2nd commercial game I bought, and the one I've played the most. I ran the trial, thought it worked great, and bought it. I've had a lot of fun with this... there's no gas pedal.. your foot is in the carbeurator from the GO!, and unless you wanna tap the screen and brake like a little girl, just hang onto the steering wheel (the phone), and guide your way through. Hours of fun and challenges here. I like this because it's got some challenge to it, and the cars seem to be very realistic in their reactions. Need for Speed Undercover is by Electronic Arts is $4.99 and has a free trial. SurfCube Browser is another app by the folks that did the GuitarTuner I reviewed on Monday. You have to see SurfCube to believe it. You've probably seen the YouTube video, if not check SilverlightCream number 1017. The app works very solid, and just as the video demonstrates. I downloaded and tried this, and it immediately did 2 things: bought it, and pinned it to my start page. I like this because it's fun to work with, and it works great as a browser. I'm about *this* close to replacing the IE tile on my front page with SurfCube. SurfCube Browser is by Kinabalu Innovation Limited and is $1.99 and has a free trial. Coming in with another News app is United Nations News by Justin Angel. This is definitely a news aggregator for 'grown ups'... news, photos, videos, and radio broadcsts from the international community all in one very slick app. This is an amazingly well thought-out and complete app. Even better yet, Justin has the code on CodePlex. A very well-done International news aggregator. United Nations News is by Justin Angel and is Free. A few disclaimers: Feel free to write me about your app and tell me about it. While it would be very cool to receive a whole bunch of xap files to review, at this point, for technical reasons, I'm unable to side-load my device. Since I plan on only doing this one day a week (twice if I find time), and only 5, I may never get caught up, so if you send me some info, be patient. Re: games ... remember I'm old... I'm from the era of Colossal Cave and Zork. Duke-Nukem 2D and Captain Comic were awesome. I don't own an XBOX or any other game system, so take game reviews from my perspective -- who knows, it may be refreshing :) I won't pay for an app or game just to try it. If you expect me to test-drive your app, it's going to have to have a Free Trial. I'm still playing with the format, comments are welcome. I decided I should alphabetize the list today... so there's no order implied Let me know what you think of the idea of doing reviews, or the layout/whatever, and Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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  • boot issues - long delay, then "gave up waiting for root device"

    - by chazomaticus
    I've had this issue on and off for about two years now. I noticed it on a new (custom built) machine running 10.04 when that first came out, but then it went away until a few months ago. I've gone through a number of hard drive changes but I can't say specifically what if anything I changed hardware-wise to make it stop or start happening. I had assumed upgrading to a modern Ubuntu version would fix the issue, so I installed 12.04 beta on a spare partition last night, but it's still happening. Here's the issue. After grub loads and I select a kernel to boot, the screen goes blank save for a blinking cursor. It sits in this state for many long minutes before it finally gives up and gives me an initramfs shell with the message gave up waiting for root device (and lists the /dev/disk/by-uuid/... path it was waiting for) but no other specific diagnostic information. Now, here's the tricky part. For one, the problem is intermittent - sometimes it progresses from the blinking cursor to the Ubuntu splash boot screen in a few seconds, and once it gets that far it always continues booting fine. The really bizarre thing is that I can "force" it to "find" the root device by repeatedly pressing the space bar and hitting the machine's power button. If I tap those enough, eventually I will notice the hard drive light coming on, at which point it will always continue the boot process after a few seconds. Interestingly, if I wait slightly too long before pressing the power button (30s?), as soon as I press it I get the gave up waiting message and the initramfs shell. I've tried setting up /etc/fstab (and the grub menu.lst or whatever it's called nowadays) to use device names (e.g. /dev/sda1) instead of UUIDs, but I get the same effect just with the device name, not UUID, in the error message. I should also mention that when I boot to Windows 7, there is no issue. It boots slowly all the time just by virtue of being Windows, but it never hangs indefinitely. This would seem to indicate it's a problem in Ubuntu, not the hardware. It's pretty annoying to have to babysit the computer every time it boots. Any ideas? I'm at a loss. Not even sure how to diagnose the issue. Thanks! EDIT: Here's some dmesg output from 10.04. The 15 second gap is where it was doing nothing. I pressed the power button and space bar a few times, and the stuff at 16 seconds happened. Not sure what any of it means. [ 1.320250] scsi18 : ahci [ 1.320294] scsi19 : ahci [ 1.320320] ata19: SATA max UDMA/133 abar m8192@0xfd4fe000 port 0xfd4fe100 ir q 18 [ 1.320323] ata20: SATA max UDMA/133 abar m8192@0xfd4fe000 port 0xfd4fe180 ir q 18 [ 1.403886] usb 2-4: new high speed USB device using ehci_hcd and address 4 [ 1.562558] usb 2-4: configuration #1 chosen from 1 choice [ 16.477824] ata16: SATA link down (SStatus 0 SControl 300) [ 16.477843] ata19: SATA link down (SStatus 0 SControl 300) [ 16.477857] ata3: SATA link down (SStatus 0 SControl 300) [ 16.477895] ata15: SATA link down (SStatus 0 SControl 300) [ 16.477906] ata20: SATA link down (SStatus 0 SControl 300) [ 16.477977] ata17: SATA link down (SStatus 0 SControl 300) [ 16.478003] ata12: SATA link down (SStatus 0 SControl 300) [ 16.478046] ata13: SATA link down (SStatus 0 SControl 300) [ 16.478063] ata14: SATA link down (SStatus 0 SControl 300) [ 16.478108] ata11: SATA link down (SStatus 0 SControl 300) [ 16.478123] ata18: SATA link up 1.5 Gbps (SStatus 113 SControl 300) [ 16.478127] ata6: SATA link down (SStatus 0 SControl 300) [ 16.478157] ata5: SATA link down (SStatus 0 SControl 300) [ 16.478193] ata18.00: ATAPI: MARVELL VIRTUALL, 1.09, max UDMA/66 After that, it took its sweet time, and I had to keep hitting space bar to coax it along. Here's some more dmesg output from a little later in the boot process: [ 17.982291] input: BTC USB Multimedia Keyboard as /devices/pci0000:00/0000:00 :13.0/usb5/5-2/5-2:1.0/input/input4 [ 17.982335] generic-usb 0003:046E:5506.0002: input,hidraw1: USB HID v1.10 Key board [BTC USB Multimedia Keyboard] on usb-0000:00:13.0-2/input0 [ 18.005211] input: BTC USB Multimedia Keyboard as /devices/pci0000:00/0000:00 :13.0/usb5/5-2/5-2:1.1/input/input5 [ 18.005274] generic-usb 0003:046E:5506.0003: input,hiddev96,hidraw2: USB HID v1.10 Device [BTC USB Multimedia Keyboard] on usb-0000:00:13.0-2/input1 [ 22.484906] EXT4-fs (sda6): INFO: recovery required on readonly filesystem [ 22.484910] EXT4-fs (sda6): write access will be enabled during recovery [ 22.548542] EXT4-fs (sda6): recovery complete [ 22.549074] EXT4-fs (sda6): mounted filesystem with ordered data mode [ 32.516772] Adding 20482832k swap on /dev/sda5. Priority:-1 extents:1 across:20482832k [ 32.742540] udev: starting version 151 [ 33.002004] Bluetooth: Atheros AR30xx firmware driver ver 1.0 [ 33.008135] parport_pc 00:09: reported by Plug and Play ACPI [ 33.008186] parport0: PC-style at 0x378, irq 7 [PCSPP,TRISTATE] [ 33.012076] lp: driver loaded but no devices found [ 33.037271] ppdev: user-space parallel port driver [ 33.090256] lp0: using parport0 (interrupt-driven). Any clues in there?

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  • From Pocket to Instapaper

    - by Michael Freidgeim
    Some time ago I’ve described the issues that I’ve had since a new version of Read It Later, named Pocket, was introduced.I’ve waited with hope for a new upgrade, but I had a huge disappointment with the latest version 16 June 2012. It didn’t fixed any of the two major problems, that I  experienced since new Pocket was introduced-  1. iPad app still didn’t show many of the saved links. 2. ability to rename articles on iPad still wasn’t restored.I’ve posted the message into their forum. They did not show my comment on their forum( I would name it censorship, not moderation), but a few days ago I’ve received an email, recommending “try logging out of the app on your iPad, and back in again.” Their suggestion helped,  but I don’t understand, why it is not posted as a recommendation on their support site.So I decided to try InstAPaper on my iPad, Previously I’ve used it for Kindle. I never considered it before on iPad, because there were no free demo and I was very satisfied with RIL free and then RIL Pro. Currently InstAPaper cost $3, so the price is not an issue.I’ve checked that it has most of features that I am using(e.g. renaming, folders) and I am quite happy with it now. Actually I am using Pocket (or RIL free) for old bookmarks( I have 1000+ stored on my iPad) and for new bookmarks I am using InstAPaper.Having a solid experience with RIL/Pocket I’ve created a list of suggestions to Marco Arment to implement.1. Some pages stored in InstAPaper have removed essential sections of the text. E.g in many blogs comments are not stored in  InstAPaper. Some pages lost almost all of important links (e.g. http://www.lib.rus.ec/a/32416 -sorry, in Russian). RIL/Pocket has 2 modes to store offline- Web view and Article view. Web View includes all links/images of the original page, but it’s very reliable. Article view suppose to strip unrelated information, but often corrupts the content. I prefer to use offline Web view.InstAPaper should also support offline Web view, in case if stripped view removes important part of content.2.  Black full screen Saving on iPad Safari is very annoying. After user pressed a bookmark, the saving has some delay and then for a few seconds prevents from reading the text.Would be better to show as message on the top part(as in Pocket ). I am surprised, that  a full screen popup was  implemented recently as a desired feature. 3.There are no comments allowed on http://blog.instapaper.com/. I would prefer to post some of these notes as comments on http://blog.instapaper.com/ rather than write them in my blog and then send link to Marco.(I found recommendation how to add support of comments on tumblr at http://www.tumblr.com/help, but then realized that Marko was the lead developer ofTumblr.)4. Also there is no support forum. I understand that maintenance of the forum ican be a hassle, but stackexchange fSome time ago I’ve described the issues that I’ve had since a new version of Read It Later, named Pocket, was introduced.I’ve waited with hope for a new upgrade, but I had a huge disappointment with the latest version 16 June 2012. It didn’t fixed any of the two major problems, that I  experienced since new Pocket was introduced- orums can be referred on  http://www.instapaper.com/main/support page, i.e.http://webapps.stackexchange.com/search?q=Instapaper  or http://apple.stackexchange.com/search?q=Instapaper 5. Tags are more convenient than folders. i.e. an ability for the same article to have more than one tag. Also creating of new folders is not supported offline, which is an annoying limitation.6. I would like to have a narrow list - additionally to existing list modes have a subject only list or subject+site list to show more list items on a screen.7. Limit of 500 offline articles sounds quite big, but my RIL list exceeded 1000, so it could be a issue in the future.8. Search button on iPad version is visible, but doesn’t work- it forces to buy Premium subscription. I think, that it’s not correct. If the button in a paid version is visible and enabled, it should  provide  a working functionality, e.g. search in article names only. And leave full-text search for the premium support.9..Copy URL is an important operation and deserves to be in a first level of Action menu, rather than in Share sub-menu.I’ve also have comment re post http://www.marco.org/2011/04/28/removed-instapaper-free. Marco Arment  explained, why he doesn’t provide free version of Instapaper.  I believe that he is loosing essential part of his customers. When I decided which of iPad application to choose, I’ve selected RIL, because I was able to play with free version, and I liked it. I didn’t have a chance to compare RIL and InstAPaper on iPad, so I’ve bought  RIL pro. For a user there is no point to pay even $3 , if there are similar free product, that user can try and see, is it suitable for him/her.I’ve also played with Readability. It doesn’t have folders or tags(which is very important for me), but nicely supports full text search

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  • Remote Workers...We're Not That Bad!

    - by user12601034
    I work from home a lot – my team is located in different cities and countries, my manager is in a different city, and most of our work is done via conference calls, email and collaboration through Oracle Social Network. We’ve figured out how to be effective and involve team members, regardless of where we are all located. When I mention that I work from home, a lot of my friends will laugh, roll their eyes or use their fingers to make quotation marks around “work from home.” Their belief is that I’m sitting at home, eating bon-bons and watching television. The attempts at humor only multiply when they know that my husband also mostly works from home. So, it was with great joy that I read the Lifehacker article Why Remote Workers Are More (Yes, More) Engaged. I’m not going to re-write the article for you, but four highlights from the article include: Proximity breeds complacency –because communicating with employees sitting next to you is so easy, you may not do it well. Absence makes people try harder to connect – because you have to make an effort to connect to your team, you tend to pay better attention when you do connect Leaders of virtual team make better use of tools – when working remotely, you will use technology (many different forms of it) to connect with your team. This daily use of the tools makes you more proficient with those tools Leaders of far-flung teams maximize the time spent together – getting together takes effort, time and money, so leaders tend to filter out distractions when teams do get together. These points made me happy because I’ve seen the same things play out in my team located around the world. And I’m not saying that a virtual team is more effective than a co-located team – but my virtual team doesn’t have the option of filing into a conference room for a face-to-face meeting whenever we want. Instead, we have to figure out how to work effectively without meeting face-to-face. Am I more engaged as a remote worker? I’d like to think that I am. I’ve been on calls with colleagues at 3am – this would never happen if my only option was to be in the office. I can leave my “office” to pick up my kids from school…and I’m willingly back online after kids are in bed to finish up anything I need to. Oracle Social Network lets me use my iPad to engage with my teammates when I’m waiting at music lessons, the doctor’s office or any place else with a network connection. I feel like I’m more connected with my team, and I feel like I’m more connected with my family life. So yes, I am a remote worker, and I am engaged. If you lead a virtual team, I challenge you to increase the ways that you communicate to effectively engage your team. If you are on a virtual team, I challenge you to think about how you might interact with team members to keep both them and yourself engaged in your work. And if you have some great ideas on how to make virtual teams (and workers) effective and engaged, please share those ideas in the comments! Now, if you’ll excuse me, I need to go get a bon-bon...   :) Normal 0 false false false EN-US X-NONE X-NONE /* 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-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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  • High Availability for IaaS, PaaS and SaaS in the Cloud

    - by BuckWoody
    Outages, natural disasters and unforeseen events have proved that even in a distributed architecture, you need to plan for High Availability (HA). In this entry I'll explain a few considerations for HA within Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). In a separate post I'll talk more about Disaster Recovery (DR), since each paradigm has a different way to handle that. Planning for HA in IaaS IaaS involves Virtual Machines - so in effect, an HA strategy here takes on many of the same characteristics as it would on-premises. The primary difference is that the vendor controls the hardware, so you need to verify what they do for things like local redundancy and so on from the hardware perspective. As far as what you can control and plan for, the primary factors fall into three areas: multiple instances, geographical dispersion and task-switching. In almost every cloud vendor I've studied, to ensure your application will be protected by any level of HA, you need to have at least two of the Instances (VM's) running. This makes sense, but you might assume that the vendor just takes care of that for you - they don't. If a single VM goes down (for whatever reason) then the access to it is lost. Depending on multiple factors, you might be able to recover the data, but you should assume that you can't. You should keep a sync to another location (perhaps the vendor's storage system in another geographic datacenter or to a local location) to ensure you can continue to serve your clients. You'll also need to host the same VM's in another geographical location. Everything from a vendor outage to a network path problem could prevent your users from reaching the system, so you need to have multiple locations to handle this. This means that you'll have to figure out how to manage state between the geo's. If the system goes down in the middle of a transaction, you need to figure out what part of the process the system was in, and then re-create or transfer that state to the second set of systems. If you didn't write the software yourself, this is non-trivial. You'll also need a manual or automatic process to detect the failure and re-route the traffic to your secondary location. You could flip a DNS entry (if your application can tolerate that) or invoke another process to alias the first system to the second, such as load-balancing and so on. There are many options, but all of them involve coding the state into the application layer. If you've simply moved a state-ful application to VM's, you may not be able to easily implement an HA solution. Planning for HA in PaaS Implementing HA in PaaS is a bit simpler, since it's built on the concept of stateless applications deployment. Once again, you need at least two copies of each element in the solution (web roles, worker roles, etc.) to remain available in a single datacenter. Also, you need to deploy the application again in a separate geo, but the advantage here is that you could work out a "shared storage" model such that state is auto-balanced across the world. In fact, you don't have to maintain a "DR" site, the alternate location can be live and serving clients, and only take on extra load if the other site is not available. In Windows Azure, you can use the Traffic Manager service top route the requests as a type of auto balancer. Even with these benefits, I recommend a second backup of storage in another geographic location. Storage is inexpensive; and that second copy can be used for not only HA but DR. Planning for HA in SaaS In Software-as-a-Service (such as Office 365, or Hadoop in Windows Azure) You have far less control over the HA solution, although you still maintain the responsibility to ensure you have it. Since each SaaS is different, check with the vendor on the solution for HA - and make sure you understand what they do and what you are responsible for. They may have no HA for that solution, or pin it to a particular geo, or perhaps they have a massive HA built in with automatic load balancing (which is often the case).   All of these options (with the exception of SaaS) involve higher costs for the design. Do not sacrifice reliability for cost - that will always cost you more in the end. Build in the redundancy and HA at the very outset of the project - if you try to tack it on later in the process the business will push back and potentially not implement HA. References: http://www.bing.com/search?q=windows+azure+High+Availability  (each type of implementation is different, so I'm routing you to a search on the topic - look for the "Patterns and Practices" results for the area in Azure you're interested in)

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  • Microsoft Forcing Dev/Partners Hands on Win 8 Through Certification

    - by D'Arcy Lussier
    I remember 2.5 years ago when Microsoft dropped a bomb on the Microsoft Partner community: all Gold competencies would require .NET 4 based premiere certifications (MCPD). Problem was, this gave a window of about 6 months for partners to update their employees’ certifications. At the place I was working, I put together an aggressive plan and we were able to attain the certs needed. Microsoft is always open that the certification requirements will change as the industry changes. .NET 1.0 certifications are useless here in 2012, and rightfully so they’ve been retired for a long time now. But now we’re seeing a new tactic by Microsoft – shifting gears away from certifications that speak to what industry needs and more to the Windows 8 agenda. Consider that currently the premiere development certification is the Microsoft Certified Professional Developer, which comes in three flavours – Web, Windows, and Azure. All require WCF and Data Access exams, as well as one that deals with the associated base technologies (ASP.NET, WinForms/WPF, Azure), and one that ties all three together in a solution-based exam. For Microsoft-based organizations, these skills aren’t just valid but necessary in building Microsoft applications. But the MCPD is being replaced with our old friend Microsoft Certified Solutions Developer (MCSD). So far, Microsoft has only released two types of MCSD – Web and Windows Store Apps. Windows Store Apps?! In a push to move developers to create WinRT-based applications, desktop development is now considered a second-class citizen in the eyes of Redmond. Also interesting are the language options for the exams: HTML5 and C#. Sorry VB folks, its time to embrace curly braces whether they be JavaScript or C#. Consider too the skills being assessed for the Windows Store Apps: Get your MCSD: Windows Store Apps Using HTML5 Get your MCSD: Windows Store Apps Using C# *Image Source: http://www.microsoft.com/learning/en/us/certification/mcsd-windows-store-apps.aspx Nov 21/2012 If you look at the skills being tested in each exam, you’ll find that skills like WCF and Data Access are downplayed compared to things like integrating Charms, facilitating Search, programming for the microphone and camera – all very Windows 8 focussed items. Where this becomes maddening is that Microsoft is still pushing Windows 7 with enterprise clients. According to a ZDNet article, Microsoft wants to see Windows 7 on 70% of enterprise desktops by mid 2013. Assuming they somehow meet that (its a pretty lofty goal), there’s years of traditional desktop-based development that will still be required at some level. For those thinking they’ll just write and stick with the MCPD certification, note that most exams that go towards that certification will be retired at the end of July 2013! (Read the small print). And while details haven’t been finalized, its a safe bet that MCPD certifications eventually won’t count towards Gold-level competencies in the Microsoft Partner program. What this means for Microsoft Partners and Developers is that certification for desktop development is going to be limited to Windows Store Apps unless Microsoft re-introduces a traditional desktop (WPF) based MCSD cert. Web Application Development – It’s Not All Bad There’s big changes on the web side of certification, but I actually see these changes as being for the good! Check out the new exam requirements for MCSD – Web Applications: Get your MCSD: Web Applications certification *Image Source: http://www.microsoft.com/learning/en/us/certification/cert-mcsd-web-applications.aspx Nov 21, 2012 We now *start* with HTML5, JavaScript, and CSS3! Now I’m sure that these will be slanted towards web development in IE, and I can hear designers everywhere bemoaning the CSS/IE combination. Still, I applaud Microsoft for adopting HTML5 as the go-to web technology and requiring certified developers to prove they have skills in the basics of web dev. The fact that the second exam clearly states “MVC Web Applications” shows that Web Forms is truly legacy and deprecated. That’s not to say there aren’t those out there that are still supporting or (for whatever reason) doing new dev with Web Forms, but this move by Microsoft is telling the community they better get on the MVC bandwagon if they want to stay current. Fantastic! And of course Azure needs to be here as well, and this is where the Microsoft agenda fits in. It’s no secret that there’s been a huge push in getting developers on to Azure. I don’t see this as being a bad thing either, as cloud computing (whether Azure, private, or 3rd party) is a necessary skill for developers to have here in 2012. The cynic in me realizes that the HTML5/JavaScript/CSS push wouldn’t be as prominent though if not for the Windows 8 Store App play, where HTML5 is a first class citizen (and an available language for the MCSD Windows Store App cert). In this case, the desktop developers loss is the web developers gain. Get Ready for Changes In addition to the changes in certifications, the Microsoft Partner competencies are going through changes as well. Web and Software Development are being merged into a single competency, meaning that licenses you would have received from having both as Gold are reduced. Other competencies are either being removed or changed, as are the exam requirements. In the same way that we’re seeing faster release cycles from Microsoft, so too will we see the Microsoft Partner Program and MS Certifications evolve faster than ever before. Many of us got caught in the last wave of changes, but this time we can see the wave coming – and it looks pretty big!

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  • What Counts For a DBA: Fitness

    - by Louis Davidson
    If you know me, you can probably guess that physical exercise is not really my thing. There was a time in my past when it a larger part of my life, but even then never in the same sort of passionate way as a number of our SQL friends.  For me, I find that mental exercise satisfies what I believe to be the same inner need that drives people to run farther than I like to drive on most Saturday mornings, and it is certainly just as addictive. Mental fitness shares many common traits with physical fitness, especially the need to attain it through repetitive training. I only wish that mental training burned off a bacon cheeseburger in the same manner as does jogging around a dewy park on Saturday morning. In physical training, there are at least two goals, the first of which is to be physically able to do a task. The second is to train the brain to perform the task without thinking too hard about it. No matter how long it has been since you last rode a bike, you will be almost certainly be able to hop on and start riding without thinking about the process of pedaling or balancing. If you’ve never ridden a bike, you could be a physics professor /Olympic athlete and still crash the first few times you try, even though you are as strong as an ox and your knowledge of the physics of bicycle riding makes the concept child’s play. For programming tasks, the process is very similar. As a DBA, you will come to know intuitively how to backup, optimize, and secure database systems. As a data programmer, you will work to instinctively use the clauses of Transact-SQL DML so that, when you need to group data three ways (and not four), you will know to use the GROUP BY clause with GROUPING SETS without resorting to a search engine.  You have the skill. Making it naturally then requires repetition and experience is the primary requirement, not just simply learning about a topic. The hardest part of being really good at something is this difference between knowledge and skill. I have recently taken several informative training classes with Kimball University on data warehousing and ETL. Now I have a lot more knowledge about designing data warehouses than before. I have also done a good bit of data warehouse designing of late and have started to improve to some level of proficiency with the theory. Yet, for all of this head knowledge, it is still a struggle to take what I have learned and apply it to the designs I am working on.  Data warehousing is still a task that is not yet deeply ingrained in my brain muscle memory. On the other hand, relational database design is something that no matter how much or how little I may get to do it, I am comfortable doing it. I have done it as a profession now for well over a decade, I teach classes on it, and I also have done (and continue to do) a lot of mental training beyond the work day. Sometimes the training is just basic education, some reading blogs and attending sessions at PASS events.  My best training comes from spending time working on other people’s design issues in forums (though not nearly as much as I would like to lately). Working through other people’s problems is a great way to exercise your brain on problems with which you’re not immediately familiar. The final bit of exercise I find useful for cultivating mental fitness for a data professional is also probably the nerdiest thing that I will ever suggest you do.  Akin to running in place, the idea is to work through designs in your head. I have designed more than one database system that would revolutionize grocery store operations, sales at my local Target store, the ordering process at Amazon, and ways to improve Disney World operations to get me through a line faster (some of which they are starting to implement without any of my help.) Never are the designs truly fleshed out, but enough to work through structures and processes.  On “paper”, I have designed database systems to catalog things as trivial as my Lego creations, rental car companies and my audio and video collections. Once I get the database designed mentally, sometimes I will create the database, add some data (often using Red-Gate’s Data Generator), and write a few queries to see if a concept was realistic, but I will rarely fully flesh out the database since I have no desire to do any user interface programming anymore.  The mental training allows me to keep in practice for when the time comes to do the work I love the most for real…even if I have been spending most of my work time lately building data warehouses.  If you are really strong of mind and body, perhaps you can mix a mental run with a physical run; though don’t run off of a cliff while contemplating how you might design a database to catalog the trees on a mountain…that would be contradictory to the purpose of both types of exercise.

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  • Rebuilding CoasterBuzz, Part IV: Dependency injection, it's what's for breakfast

    - by Jeff
    (Repost from my personal blog.) This is another post in a series about rebuilding one of my Web sites, which has been around for 12 years. I hope to relaunch soon. More: Part I: Evolution, and death to WCF Part II: Hot data objects Part III: The architecture using the "Web stack of love" If anything generally good for the craft has come out of the rise of ASP.NET MVC, it's that people are more likely to use dependency injection, and loosely couple the pieces parts of their applications. A lot of the emphasis on coding this way has been to facilitate unit testing, and that's awesome. Unit testing makes me feel a lot less like a hack, and a lot more confident in what I'm doing. Dependency injection is pretty straight forward. It says, "Given an instance of this class, I need instances of other classes, defined not by their concrete implementations, but their interfaces." Probably the first place a developer exercises this in when having a class talk to some kind of data repository. For a very simple example, pretend the FooService has to get some Foo. It looks like this: public class FooService {    public FooService(IFooRepository fooRepo)    {       _fooRepo = fooRepo;    }    private readonly IFooRepository _fooRepo;    public Foo GetMeFoo()    {       return _fooRepo.FooFromDatabase();    } } When we need the FooService, we ask the dependency container to get it for us. It says, "You'll need an IFooRepository in that, so let me see what that's mapped to, and put it in there for you." Why is this good for you? It's good because your FooService doesn't know or care about how you get some foo. You can stub out what the methods and properties on a fake IFooRepository might return, and test just the FooService. I don't want to get too far into unit testing, but it's the most commonly cited reason to use DI containers in MVC. What I wanted to mention is how there's another benefit in a project like mine, where I have to glue together a bunch of stuff. For example, when I have someone sign up for a new account on CoasterBuzz, I'm actually using POP Forums' new account mailer, which composes a bunch of text that includes a link to verify your account. The thing is, I want to use custom text and some other logic that's specific to CoasterBuzz. To accomplish this, I make a new class that inherits from the forum's NewAccountMailer, and override some stuff. Easy enough. Then I use Ninject, the DI container I'm using, to unbind the forum's implementation, and substitute my own. Ninject uses something called a NinjectModule to bind interfaces to concrete implementations. The forum has its own module, and then the CoasterBuzz module is loaded second. The CB module has two lines of code to swap out the mailer implementation: Unbind<PopForums.Email.INewAccountMailer>(); Bind<PopForums.Email.INewAccountMailer>().To<CbNewAccountMailer>(); Piece of cake! Now, when code asks the DI container for an INewAccountMailer, it gets my custom implementation instead. This is a lot easier to deal with than some of the alternatives. I could do some copy-paste, but then I'm not using well-tested code from the forum. I could write stuff from scratch, but then I'm throwing away a bunch of logic I've already written (in this case, stuff around e-mail, e-mail settings, mail delivery failures). There are other places where the DI container comes in handy. For example, CoasterBuzz does a number of custom things with user profiles, and special content for paid members. It uses the forum as the core piece to managing users, so I can ask the container to get me instances of classes that do user lookups, for example, and have zero care about how the forum handles database calls, configuration, etc. What a great world to live in, compared to ten years ago. Sure, the primary interest in DI is around the "separation of concerns" and facilitating unit testing, but as your library grows and you use more open source, it starts to be the glue that pulls everything together.

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  • yield – Just yet another sexy c# keyword?

    - by George Mamaladze
    yield (see NSDN c# reference) operator came I guess with .NET 2.0 and I my feeling is that it’s not as wide used as it could (or should) be.   I am not going to talk here about necessarity and advantages of using iterator pattern when accessing custom sequences (just google it).   Let’s look at it from the clean code point of view. Let's see if it really helps us to keep our code understandable, reusable and testable.   Let’s say we want to iterate a tree and do something with it’s nodes, for instance calculate a sum of their values. So the most elegant way would be to build a recursive method performing a classic depth traversal returning the sum.           private int CalculateTreeSum(Node top)         {             int sumOfChildNodes = 0;             foreach (Node childNode in top.ChildNodes)             {                 sumOfChildNodes += CalculateTreeSum(childNode);             }             return top.Value + sumOfChildNodes;         }     “Do One Thing” Nevertheless it violates one of the most important rules “Do One Thing”. Our  method CalculateTreeSum does two things at the same time. It travels inside the tree and performs some computation – in this case calculates sum. Doing two things in one method is definitely a bad thing because of several reasons: ·          Understandability: Readability / refactoring ·          Reuseability: when overriding - no chance to override computation without copying iteration code and vice versa. ·          Testability: you are not able to test computation without constructing the tree and you are not able to test correctness of tree iteration.   I want to spend some more words on this last issue. How do you test the method CalculateTreeSum when it contains two in one: computation & iteration? The only chance is to construct a test tree and assert the result of the method call, in our case the sum against our expectation. And if the test fails you do not know wether was the computation algorithm wrong or was that the iteration? At the end to top it all off I tell you: according to Murphy’s Law the iteration will have a bug as well as the calculation. Both bugs in a combination will cause the sum to be accidentally exactly the same you expect and the test will PASS. J   Ok let’s use yield! That’s why it is generally a very good idea not to mix but isolate “things”. Ok let’s use yield!           private int CalculateTreeSumClean(Node top)         {             IEnumerable<Node> treeNodes = GetTreeNodes(top);             return CalculateSum(treeNodes);         }             private int CalculateSum(IEnumerable<Node> nodes)         {             int sumOfNodes = 0;             foreach (Node node in nodes)             {                 sumOfNodes += node.Value;             }             return sumOfNodes;         }           private IEnumerable<Node> GetTreeNodes(Node top)         {             yield return top;             foreach (Node childNode in top.ChildNodes)             {                 foreach (Node currentNode in GetTreeNodes(childNode))                 {                     yield return currentNode;                 }             }         }   Two methods does not know anything about each other. One contains calculation logic another jut the iteration logic. You can relpace the tree iteration algorithm from depth traversal to breath trevaersal or use stack or visitor pattern instead of recursion. This will not influence your calculation logic. And vice versa you can relace the sum with product or do whatever you want with node values, the calculateion algorithm is not aware of beeng working on some tree or graph.  How about not using yield? Now let’s ask the question – what if we do not have yield operator? The brief look at the generated code gives us an answer. The compiler generates a 150 lines long class to implement the iteration logic.       [CompilerGenerated]     private sealed class <GetTreeNodes>d__0 : IEnumerable<Node>, IEnumerable, IEnumerator<Node>, IEnumerator, IDisposable     {         ...        150 Lines of generated code        ...     }   Often we compromise code readability, cleanness, testability, etc. – to reduce number of classes, code lines, keystrokes and mouse clicks. This is the human nature - we are lazy. Knowing and using such a sexy construct like yield, allows us to be lazy, write very few lines of code and at the same time stay clean and do one thing in a method. That's why I generally welcome using staff like that.   Note: The above used recursive depth traversal algorithm is possibly the compact one but not the best one from the performance and memory utilization point of view. It was taken to emphasize on other primary aspects of this post.

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  • Loading XML file containing leading zeros with SSIS preserving the zeros

    - by Compudicted
    Visiting the MSDN SQL Server Integration Services Forum oftentimes I could see that people would pop up asking this question: “why I am not able to load an element from an XML file that contains zeros so the leading/trailing zeros would remain intact?”. I started to suspect that such a trivial and often-required operation perhaps is being misunderstood by the developer community. I would also like to add that the whole state of affairs surrounding the XML today is probably also going to be increasingly affected by a motion of people who dislike XML in general and many aspects of it as XSD and XSLT invoke a negative reaction at best. Nevertheless, XML is in wide use today and its importance as a bridge between diverse systems is ever increasing. Therefore, I deiced to write up an example of loading an arbitrary XML file that contains leading zeros in one of its elements using SSIS so the leading zeros would be preserved keeping in mind the goal on simplicity into a table in SQL Server database. To start off bring up your BIDS (running as admin) and add a new Data Flow Task (DFT). This DFT will serve as container to adding our XML processing elements (besides, the XML Source is not available anywhere else other than from within the DFT). Double-click your DFT and drag and drop the XMS Source component from the Tool Box’s Data Flow Sources. Now, let the fun begin! Being inspired by the upcoming Christmas I created a simple XML file with one set of data that contains an imaginary SSN number of Rudolph containing several leading zeros like 0000003. This file can be viewed here. To configure the XML Source of course it is quite intuitive to point it to our XML file, next what the XML source needs is either an embedded schema (XSD) or it can generate one for us. In lack of the one I opted to auto-generate it for me and I ended up with an XSD that looked like: <?xml version="1.0"?> <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="XMasEvent"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="CaseInfo"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="ID" type="xs:unsignedByte" /> <xs:element minOccurs="0" name="CreatedDate" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="LastName" type="xs:string" /> <xs:element minOccurs="0" name="FirstName" type="xs:string" /> <xs:element minOccurs="0" name="SSN" type="xs:unsignedByte" /> <!-- Becomes string -- > <xs:element minOccurs="0" name="DOB" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="Event" type="xs:string" /> <xs:element minOccurs="0" name="ClosedDate" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> As an aside on the XML file: if your XML file does not contain the outer node (<XMasEvent>) then you may end up in a situation where you see just one field in the output. Now please note that the SSN element’s data type was chosen to be of unsignedByte (and this is for a reason). The reason is stemming from the fact all our figures in the element are digits, this is good, but this is not exactly what we need, because if we will attempt to load the data with this XSD then we are going to either get errors on the destination or most typically lose the leading zeros. So the next intuitive choice is to change the data type to string. Besides, if a SSIS package was already created based on this XSD and the data type change was done thereafter, one should re-set the metadata by right-clicking the XML Source and choosing “Advanced Editor” in which there is a refresh button at the bottom left which will do the trick. So far so good, we are ready to load our XML file, well actually yes, and no, in my experience typically some data conversion may be required. So depending on your data destination you may need to tweak the data types targeted. Let’s add a Data Conversion Task to our DFT. Your package should look like: To make the story short I only will cover the SSN field, so in my data source the target SQL Table has it as nchar(10) and we chose string in our XSD (yes, this is a big difference), under such circumstances the SSIS will complain. So will go and manipulate on the data type of SSN by making it Unicode String (DT_WSTR), World String per se. The conversion should look like: The peek at the Metadata: We are almost there, now all we need is to configure the destination. For simplicity I chose SQL Server Destination. The mapping is a breeze, F5 and I am able to insert my data into SQL Server now! Checking the zeros – they are all intact!

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  • Understanding the 'High Performance' meaning in Extreme Transaction Processing

    - by kyap
    Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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  • SQL SERVER – Backing Up and Recovering the Tail End of a Transaction Log – Notes from the Field #042

    - by Pinal Dave
    [Notes from Pinal]: The biggest challenge which people face is not taking backup, but the biggest challenge is to restore a backup successfully. I have seen so many different examples where users have failed to restore their database because they made some mistake while they take backup and were not aware of the same. Tail Log backup was such an issue in earlier version of SQL Server but in the latest version of SQL Server, Microsoft team has fixed the confusion with additional information on the backup and restore screen itself. Now they have additional information, there are a few more people confused as they have no clue about this. Previously they did not find this as a issue and now they are finding tail log as a new learning. Linchpin People are database coaches and wellness experts for a data driven world. In this 42nd episode of the Notes from the Fields series database expert Tim Radney (partner at Linchpin People) explains in a very simple words, Backing Up and Recovering the Tail End of a Transaction Log. Many times when restoring a database over an existing database SQL Server will warn you about needing to make a tail end of the log backup. This might be your reminder that you have to choose to overwrite the database or could be your reminder that you are about to write over and lose any transactions since the last transaction log backup. You might be asking yourself “What is the tail end of the transaction log”. The tail end of the transaction log is simply any committed transactions that have occurred since the last transaction log backup. This is a very crucial part of a recovery strategy if you are lucky enough to be able to capture this part of the log. Most organizations have chosen to accept some amount of data loss. You might be shaking your head at this statement however if your organization is taking transaction logs backup every 15 minutes, then your potential risk of data loss is up to 15 minutes. Depending on the extent of the issue causing you to have to perform a restore, you may or may not have access to the transaction log (LDF) to be able to back up those vital transactions. For example, if the storage array or disk that holds your transaction log file becomes corrupt or damaged then you wouldn’t be able to recover the tail end of the log. If you do have access to the physical log file then you can still back up the tail end of the log. In 2013 I presented a session at the PASS Summit called “The Ultimate Tail Log Backup and Restore” and have been invited back this year to present it again. During this session I demonstrate how you can back up the tail end of the log even after the data file becomes corrupt. In my demonstration I set my database offline and then delete the data file (MDF). The database can’t become more corrupt than that. I attempt to bring the database back online to change the state to RECOVERY PENDING and then backup the tail end of the log. I can do this by specifying WITH NO_TRUNCATE. Using NO_TRUNCATE is equivalent to specifying both COPY_ONLY and CONTINUE_AFTER_ERROR. It as its name says, does not try to truncate the log. This is a great demo however how could I achieve backing up the tail end of the log if the failure destroys my entire instance of SQL and all I had was the LDF file? During my demonstration I also demonstrate that I can attach the log file to a database on another instance and then back up the tail end of the log. If I am performing proper backups then my most recent full, differential and log files should be on a server other than the one that crashed. I am able to achieve this task by creating new database with the same name as the failed database. I then set the database offline, delete my data file and overwrite the log with my good log file. I attempt to bring the database back online and then backup the log with NO_TRUNCATE just like in the first example. I encourage each of you to view my blog post and watch the video demonstration on how to perform these tasks. I really hope that none of you ever have to perform this in production, however it is a really good idea to know how to do this just in case. It really isn’t a matter of “IF” you will have to perform a restore of a production system but more of a “WHEN”. Being able to recover the tail end of the log in these sever cases could be the difference of having to notify all your business customers of data loss or not. If you want me to take a look at your server and its settings, or if your server is facing any issue we can Fix Your SQL Server. Note: Tim has also written an excellent book on SQL Backup and Recovery, a must have for everyone. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • Custom Configuration Section Handlers

    Most .NET developers who need to store something in configuration tend to use appSettings for this purpose, in my experience.  More recently, the framework itself has helped things by adding the <connectionStrings /> section so at least these are in their own section and not adding to the appSettings clutter that pollutes most apps.  I recommend avoiding appSettings for several reasons.  In addition to those listed there, I would add that strong typing and validation are additional reasons to go the custom configuration section route. For my ASP.NET Tips and Tricks talk, I use the following example, which is a simple DemoSettings class that includes two fields.  The first is an integer representing how many attendees there are present for the talk, and the second is the title of the talk.  The setup in web.config is as follows: <configSections> <section name="DemoSettings" type="ASPNETTipsAndTricks.Code.DemoSettings" /> </configSections>   <DemoSettings sessionAttendees="100" title="ASP.NET Tips and Tricks DevConnections Spring 2010" /> Referencing the values in code is strongly typed and straightforward.  Here I have a page that exposes two properties which internally get their values from the configuration section handler: public partial class CustomConfig1 : System.Web.UI.Page { public string SessionTitle { get { return DemoSettings.Settings.Title; } } public int SessionAttendees { get { return DemoSettings.Settings.SessionAttendees; } } } Note that the settings are only read from the config file once after that they are cached so there is no need to be concerned about excessive file access. Now weve seen how to set it up on the config file and how to refer to the settings in code.  All that remains is to see the file itself: public class DemoSettings : ConfigurationSection { private static DemoSettings settings = ConfigurationManager.GetSection("DemoSettings") as DemoSettings; public static DemoSettings Settings{ get { return settings;} }   [ConfigurationProperty("sessionAttendees" , DefaultValue = 200 , IsRequired = false)] [IntegerValidator(MinValue = 1 , MaxValue = 10000)] public int SessionAttendees { get { return (int)this["sessionAttendees"]; } set { this["sessionAttendees"] = value; } }   [ConfigurationProperty("title" , IsRequired = true)] [StringValidator(InvalidCharacters = "~!@#$%^&*()[]{}/;\"|\\")] public string Title { get { return (string)this["title"]; } set { this["title"] = value; }   } } The class is pretty straightforward, but there are some important components to note.  First, it must inherit from System.Configuration.ConfigurationSection.  Next, as a convention I like to have a static settings member that is responsible for pulling out the section when the class is first referenced, and further to expose this collection via a static readonly property, Settings.  Note that the types of both of these are the type of my class, DemoSettings. The properties of the class, SessionAttendees and Title, should map to the attributes of the config element in the XML file.  The [ConfigurationProperty] attribute allows you to map the attribute name to the property name (thus using both XML standard naming conventions and C# naming conventions).  In addition, you can specify a default value to use if nothing is specified in the config file, and whether or not the setting must be provided (IsRequired).  If it is required, then it doesnt make sense to include a default value. Beyond defaults and required, you can specify more advanced validation rules for the configuration values using additional C# attributes, such as [IntegerValidator] and [StringValidator].  Using these, you can declaratively specify that your configuration values be in a given range, or omit certain forbidden characters, for instance.  Of course you can write your own custom validation attributes, and there are others specified in System.Configuration. Individual sections can also be loaded from separate files, using syntax like this: <DemoSettings configSource="demosettings.config" /> Summary Using a custom configuration section handler is not hard.  If your application or component requires configuration, I recommend creating a custom configuration handler dedicated to your app or component.  Doing so will reduce the clutter in appSettings, will provide you with strong typing and validation, and will make it much easier for other developers or system administrators to locate and understand the various configuration values that are necessary for a given application. Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • T-SQL Tuesday #34: Help! I Need Somebody!

    - by Most Valuable Yak (Rob Volk)
    Welcome everyone to T-SQL Tuesday Episode 34!  When last we tuned in, Mike Fal (b|t) hosted Trick Shots.  These highlighted techniques or tricks that you figured out on your own which helped you understand SQL Server better. This month, I'm asking you to look back this past week, year, century, or hour...to a time when you COULDN'T figure it out.  When you were stuck on a SQL Server problem and you had to seek help. In the beginning... SQL Server has changed a lot since I started with it.  <Cranky Old Guy> Back in my day, Books Online was neither.  There were no blogs. Google was the third-place search site. There were perhaps two or three community forums where you could ask questions.  (Besides the Microsoft newsgroups...which you had to access with Usenet.  And endure the wrath of...Celko.)  Your "training" was reading a book, made from real dead trees, that you bought from your choice of brick-and-mortar bookstore. And except for your local user groups, there were no conferences, seminars, SQL Saturdays, or any online video hookups where you could interact with a person. You'd have to call Microsoft Support...on the phone...a LANDLINE phone.  And none of this "SQL Family" business!</Cranky Old Guy> Even now, with all these excellent resources available, it's still daunting for a beginner to seek help for SQL Server.  The product is roughly 1247.4523 times larger than it was 15 years ago, and it's simply impossible to know everything about it.*  So whether you are a beginner, or a seasoned pro of over a decade's experience, what do you do when you need help on SQL Server? That's so meta... In the spirit of offering help, here are some suggestions for your topic: Tell us about a person or SQL Server community who have been helpful to you.  It can be about a technical problem, or not, e.g. someone who volunteered for your local SQL Saturday.  Sing their praises!  Let the world know who they are! Do you have any tricks for using Books Online?  Do you use the locally installed product, or are you completely online with BOL/MSDN/Technet, and why? If you've been using SQL Server for over 10 years, how has your help-seeking changed? Are you using Twitter, StackOverflow, MSDN Forums, or another resource that didn't exist when you started? What made you switch? Do you spend more time helping others than seeking help? What motivates you to help, and how do you contribute? Structure your post along the lyrics to The Beatles song Help! Audio or video renditions are particularly welcome! Lyrics must include reference to SQL Server terminology or community, and performances must be in your voice or include you playing an instrument. These are just suggestions, you are free to write whatever you like.  Bonus points if you can incorporate ALL of these into a single post.  (Or you can do multiple posts, we're flexible like that.)  Help us help others by showing how others helped you! Legalese, Your Rights, Yada yada... If you would like to participate in T-SQL Tuesday please be sure to follow the rules below: Your blog post must be published between Tuesday, September 11, 2012 00:00:00 GMT and Wednesday, September 12, 2012 00:00:00 GMT. Include the T-SQL Tuesday logo (above) and hyperlink it back to this post. If you don’t see your post in trackbacks, add the link to the comments below. If you are on Twitter please tweet your blog using the #TSQL2sDay hashtag.  I can be contacted there as @sql_r, in case you have questions or problems with comments/trackback.  I'll have a follow-up post listing all the contributions as soon as I can. Thank you all for participating, and special thanks to Adam Machanic (b|t) for all his help and for continuing this series!

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  • A Knights Tale

    - by Phil Factor
    There are so many lessons to be learned from the story of Knight Capital losing nearly half a billion dollars as a result of a deployment gone wrong. The Knight Capital Group (KCG N) was an American global financial services firm engaging in market making, electronic execution, and institutional sales and trading. According to the recent order (File No.3.15570) against Knight Capital by U.S. Securities and Exchange Commission?, Knight had, for many years used some software which broke up incoming “parent” orders into smaller “child” orders that were then transmitted to various exchanges or trading venues for execution. A tracking ‘cumulative quantity’ function counted the number of ‘child’ orders and stopped the process once the total of child orders matched the ‘parent’ and so the parent order had been completed. Back in the mists of time, some code had been added to it  which was excuted if a particular flag was set. It was called ‘power peg’ and seems to have had a similar design and purpose, but, one guesses, would have shared the same tracking function. This code had been abandoned in 2003, but never deleted. In 2005, The tracking function was moved to an earlier point in the main process. It would seem from the account that, from that point, had that flag ever been set, the old ‘Power Peg’ would have been executed like Godzilla bursting from the ice, making child orders without limit without any tracking function. It wasn’t, presumably because the software that set the flag was removed. In 2012, nearly a decade after ‘Power Peg’ was abandoned, Knight prepared a new module to their software to cope with the imminent Retail Liquidity Program (RLP) for the New York Stock Exchange. By this time, the flag had remained unused and someone made the fateful decision to reuse it, and replace the old ‘power peg’ code with this new RLP code. Had the two actions been done together in a single automated deployment, and the new deployment tested, all would have been well. It wasn’t. To quote… “Beginning on July 27, 2012, Knight deployed the new RLP code in SMARS in stages by placing it on a limited number of servers in SMARS on successive days. During the deployment of the new code, however, one of Knight’s technicians did not copy the new code to one of the eight SMARS computer servers. Knight did not have a second technician review this deployment and no one at Knight realized that the Power Peg code had not been removed from the eighth server, nor the new RLP code added. Knight had no written procedures that required such a review.” (para 15) “On August 1, Knight received orders from broker-dealers whose customers were eligible to participate in the RLP. The seven servers that received the new code processed these orders correctly. However, orders sent with the repurposed flag to the eighth server triggered the defective Power Peg code still present on that server. As a result, this server began sending child orders to certain trading centers for execution. Because the cumulative quantity function had been moved, this server continuously sent child orders, in rapid sequence, for each incoming parent order without regard to the number of share executions Knight had already received from trading centers. Although one part of Knight’s order handling system recognized that the parent orders had been filled, this information was not communicated to SMARS.” (para 16) SMARS routed millions of orders into the market over a 45-minute period, and obtained over 4 million executions in 154 stocks for more than 397 million shares. By the time that Knight stopped sending the orders, Knight had assumed a net long position in 80 stocks of approximately $3.5 billion and a net short position in 74 stocks of approximately $3.15 billion. Knight’s shares dropped more than 20% after traders saw extreme volume spikes in a number of stocks, including preferred shares of Wells Fargo (JWF) and semiconductor company Spansion (CODE). Both stocks, which see roughly 100,000 trade per day, had changed hands more than 4 million times by late morning. Ultimately, Knight lost over $460 million from this wild 45 minutes of trading. Obviously, I’m interested in all this because, at one time, I used to write trading systems for the City of London. Obviously, the US SEC is in a far better position than any of us to work out the failings of Knight’s IT department, and the report makes for painful reading. I can’t help observing, though, that even with the breathtaking mistakes all along the way, that a robust automated deployment process that was ‘all-or-nothing’, and tested from soup to nuts would have prevented the disaster. The report reads like a Greek Tragedy. All the way along one wants to shout ‘No! not that way!’ and ‘Aargh! Don’t do it!’. As the tragedy unfolds, the audience weeps for the players, trapped by a cruel fate. All application development and deployment requires defense in depth. All IT goes wrong occasionally, but if there is a culture of defensive programming throughout, the consequences are usually containable. For financial systems, these defenses are required by statute, and ignored only by the foolish. Knight’s mistakes weren’t made by just one hapless sysadmin, but were progressive errors by an  IT culture spanning at least ten years.  One can spell these out, but I think they’re obvious. One can only hope that the industry studies what happened in detail, learns from the mistakes, and draws the right conclusions.

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  • The Enterprise is a Curmudgeon

    - by John K. Hines
    Working in an enterprise environment is a unique challenge.  There's a lot more to software development than developing software.  A project lead or Scrum Master has to manage personalities and intra-team politics, has to manage accomplishing the task at hand while creating the opportunities and a reputation for handling desirable future work, has to create a competent, happy team that actually delivers while being careful not to burn bridges or hurt feelings outside the team.  Which makes me feel surprised to read advice like: " The enterprise should figure out what is likely to work best for itself and try to use it." - Ken Schwaber, The Enterprise and Scrum. The enterprises I have experience with are fundamentally unable to be self-reflective.  It's like asking a Roman gladiator if he'd like to carve out a little space in the arena for some silent meditation.  I'm currently wondering how compatible Scrum is with the top-down hierarchy of life in a large organization.  Specifically, manufacturing-mindset, fixed-release, harmony-valuing large organizations.  Now I understand why Agile can be a better fit for companies without much organizational inertia. Recently I've talked with nearly two dozen software professionals and their managers about Scrum and Agile.  I've become convinced that a developer, team, organization, or enterprise can be Agile without using Scrum.  But I'm not sure about what process would be the best fit, in general, for an enterprise that wants to become Agile.  It's possible I should read more than just the introduction to Ken's book. I do feel prepared to answer some of the questions I had asked in a previous post: How can Agile practices (including but not limited to Scrum) be adopted in situations where the highest-placed managers in a company demand software within extremely aggressive deadlines? Answer: In a very limited capacity at the individual level.  The situation here is that the senior management of this company values any software release more than it values developer well-being, end-user experience, or software quality.  Only if the developing organization is given an immediate refactoring opportunity does this sort of development make sense to a person who values sustainable software.   How can Agile practices be adopted by teams that do not perform a continuous cycle of new development, such as those whose sole purpose is to reproduce and debug customer issues? Answer: It depends.  For Scrum in particular, I don't believe Scrum is meant to manage unpredictable work.  While you can easily adopt XP practices for bug fixing, the project-management aspects of Scrum require some predictability.  My question here was meant toward those who want to apply Scrum to non-development teams.  In some cases it works, in others it does not. How can a team measure if its development efforts are both Agile and employ sound engineering practices? Answer: I'm currently leaning toward measuring these independently.  The Agile Principles are a terrific way to measure if a software team is agile.  Sound engineering practices are those practices which help developers meet the principles.  I think Scrum is being mistakenly applied as an engineering practice when it is essentially a project management practice.  In my opinion, XP and Lean are examples of good engineering practices. How can Agile be explained in an accurate way that describes its benefits to sceptical developers and/or revenue-focused non-developers? Answer: Agile techniques will result in higher-quality, lower-cost software development.  This comes primarily from finding defects earlier in the development cycle.  If there are individual developers who do not want to collaborate, write unit tests, or refactor, then these are simply developers who are either working in an area where adding these techniques will not add value (i.e. they are an expert) or they are a developer who is satisfied with the status quo.  In the first case they should be left alone.  In the second case, the results of Agile should be demonstrated by other developers who are willing to receive recognition for their efforts.  It all comes down to individuals, doesn't it?  If you're working in an organization whose Agile adoption consists exclusively of Scrum, consider ways to form individual Agile teams to demonstrate its benefits.  These can even be virtual teams that span people across org-chart boundaries.  Once you can measure real value, whether it's Scrum, Lean, or something else, people will follow.  Even the curmudgeons.

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  • To My 24 Year Old Self, Wherever You Are&hellip;

    - by D'Arcy Lussier
    A decade is a milestone in one’s life, regardless of when it occurs. 2011 might seem like a weird year to mark a decade, but 2001 was a defining year for me. It marked my emergence into the technology industry, an unexpected loss of innocence, and triggered an ongoing struggle with faith and belief. Once you go through a valley, climbing the mountain and looking back over where you travelled, you can take in the entirety of the journey. Over the last 10 years I kept journals, and in this new year I took some time to review them. For those today that are me a decade ago, I share with you what I’ve gleamed from my experiences. Take it for what it’s worth, and safe travels on your own journeys through life. Life is a Performance-Based Sport Have confidence, believe you’re capable, but realize that life is a performance-based sport. Everything you get in life is based on whether you can show that you deserve it. Performance is also your best defense against personal attacks. Just make sure you know what standards you’re expected to hit and if people want to poke holes at you let them do the work of trying to find them. Sometimes performance won’t matter though. Good things will happen to bad people, and bad things to good people. What’s important is that you do the right things and ensure the good and bad even out in your own life. How you finish is just as important as how you start. Start strong, end strong. Respect is Your Most Prized Reward Respect is more important than status or ego. The formula is simple: Performing Well + Building Trust + Showing Dedication = Respect Focus on perfecting your craft and helping your team and respect will come. Life is a Team Sport Whatever aspect of your life, you can’t do it alone. You need to rely on the people around you and ensure you’re a positive aspect of their lives; even those that may be difficult or unpleasant. Avoid criticism and instead find ways to help colleagues and superiors better whatever environment you’re in (work, home, etc.). Don’t just highlight gaps and issues, but also come to the table with solutions. At the same time though, stand up for yourself and hold others accountable for the commitments they make to the team. A healthy team needs accountability. Give feedback early and often, and make it verbal. Issues should be dealt with immediately, and positives should be celebrated as they happen. Life is a Contact Sport Difficult moments will happen. Don’t run from them or shield yourself from experiencing them. Embrace them. They will further mold you and reveal who you will become. Find Your Tribe and Embrace Your Community We all need a tribe: a group of people that we gravitate to for support, guidance, wisdom, and friendship. Discover your tribe and immerse yourself in them. Don’t look for a non-existent tribe just to fill the need of belonging though that will leave you empty and bitter when they don’t meet your unrealistic expectations. Try to associate with people more experienced and more knowledgeable than you. You’ll always learn, and you’ll always remember you have much to learn. Put yourself out there, get involved with the community. Opportunities will present themselves. When we open ourselves up to be vulnerable, we also give others the chance to do the same. This helps us all to grow and help each other, it’s very important. And listen to your wife. (Easter *is* a romantic holiday btw, regardless of what you may think.) Don’t Believe Your Own Press Clippings (and by that I mean the ones you write) Until you have a track record of performance to refer to, any notions of grandeur are just that: notions. You lose your rookie status through trials and tribulations, not by the number of stamps in your passport. Be realistic about your own “experience and leadership” and be honest when you aren’t ready for something. And always remember: nobody really cares about you as much as you think they do. Don’t Let Assholes Get You Down The world isn’t evil, but there is evil in the world. Know the difference and don’t paint all people with the same brush. Do be wary of those that use personal beliefs to describe their business (i.e. “We’re a [religion] company”). What matters is the culture of the organization, and that will tell you the moral compass and what is truly valued. Don’t make someone or something a priority that only makes you an option. Life is unfair and enemies/opponents will succeed when you fail. Don’t waste your energy getting upset at this; the only one that will lose out is you. As mentioned earlier, nobody really cares about you as much as you think they do. Misc Ecclesiastes is bullshit. Everything is certainly *not* meaningless. Software development is about delivery, not the process. Having a great process means nothing if you don’t produce anything. Watch “The Weatherman” (“It’s not easy, but easy doesn’t enter into grownup life.”). Read Tony Dungee’s autobiography, even if you don’t like football, and even if you aren’t a Christian. Say no, don’t feel like you have to commit right away when someone asks you to.

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  • How to Implement Single Sign-On between Websites

    - by hmloo
    Introduction Single sign-on (SSO) is a way to control access to multiple related but independent systems, a user only needs to log in once and gains access to all other systems. a lot of commercial systems that provide Single sign-on solution and you can also choose some open source solutions like Opensso, CAS etc. both of them use centralized authentication and provide more robust authentication mechanism, but if each system has its own authentication mechanism, how do we provide a seamless transition between them. Here I will show you the case. How it Works The method we’ll use is based on a secret key shared between the sites. Origin site has a method to build up a hashed authentication token with some other parameters and redirect the user to the target site. variables Status Description ssoEncode required hash(ssoSharedSecret + , + ssoTime + , + ssoUserName) ssoTime required timestamp with format YYYYMMDDHHMMSS used to prevent playback attacks ssoUserName required unique username; required when a user is logged in Note : The variables will be sent via POST for security reasons Building a Single Sign-On Solution Origin Site has function to 1. Create the URL for your Request. 2. Generate required authentication parameters 3. Redirect to target site. using System; using System.Web.Security; using System.Text; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string postbackUrl = "http://www.targetsite.com/sso.aspx"; string ssoTime = DateTime.Now.ToString("yyyyMMddHHmmss"); string ssoUserName = User.Identity.Name; string ssoSharedSecret = "58ag;ai76"; // get this from config or similar string ssoHash = FormsAuthentication.HashPasswordForStoringInConfigFile(string.Format("{0},{1},{2}", ssoSharedSecret, ssoTime, ssoUserName), "md5"); string value = string.Format("{0}:{1},{2}", ssoHash,ssoTime, ssoUserName); Response.Clear(); StringBuilder sb = new StringBuilder(); sb.Append("<html>"); sb.AppendFormat(@"<body onload='document.forms[""form""].submit()'>"); sb.AppendFormat("<form name='form' action='{0}' method='post'>", postbackUrl); sb.AppendFormat("<input type='hidden' name='t' value='{0}'>", value); sb.Append("</form>"); sb.Append("</body>"); sb.Append("</html>"); Response.Write(sb.ToString()); Response.End(); } } Target Site has function to 1. Get authentication parameters. 2. Validate the parameters with shared secret. 3. If the user is valid, then do authenticate and redirect to target page. 4. If the user is invalid, then show errors and return. using System; using System.Web.Security; using System.Text; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { if (User.Identity.IsAuthenticated) { Response.Redirect("~/Default.aspx"); } } if (Request.Params.Get("t") != null) { string ticket = Request.Params.Get("t"); char[] delimiters = new char[] { ':', ',' }; string[] ssoVariable = ticket.Split(delimiters, StringSplitOptions.None); string ssoHash = ssoVariable[0]; string ssoTime = ssoVariable[1]; string ssoUserName = ssoVariable[2]; DateTime appTime = DateTime.MinValue; int offsetTime = 60; // get this from config or similar try { appTime = DateTime.ParseExact(ssoTime, "yyyyMMddHHmmss", null); } catch { //show error return; } if (Math.Abs(appTime.Subtract(DateTime.Now).TotalSeconds) > offsetTime) { //show error return; } bool isValid = false; string ssoSharedSecret = "58ag;ai76"; // get this from config or similar string hash = FormsAuthentication.HashPasswordForStoringInConfigFile(string.Format("{0},{1},{2}", ssoSharedSecret, ssoTime, ssoUserName), "md5"); if (string.Compare(ssoHash, hash, true) == 0) { if (Math.Abs(appTime.Subtract(DateTime.Now).TotalSeconds) > offsetTime) { //show error return; } else { isValid = true; } } if (isValid) { //Do authenticate; } else { //show error return; } } else { //show error } } } Summary This is a very simple and basic SSO solution, and its main advantage is its simplicity, only needs to add a single page to do SSO authentication, do not need to modify the existing system infrastructure.

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  • 2D isometric picking

    - by Bikonja
    I'm trying to implement picking in my isometric 2D game, however, I am failing. First of all, I've searched for a solution and came to several, different equations and even a solution using matrices. I tried implementing every single one, but none of them seem to work for me. The idea is that I have an array of tiles, with each tile having it's x and y coordinates specified (in this simplified example it's by it's position in the array). I'm thinking that the tile (0, 0) should be on the left, (max, 0) on top, (0, max) on the bottom and (max, max) on the right. I came up with this loop for drawing, which googling seems to have verified as the correct solution, as has the rendered scene (ofcourse, it could still be wrong, also, forgive the messy names and stuff, it's just a WIP proof of concept code) // Draw code int col = 0; int row = 0; for (int i = 0; i < nrOfTiles; ++i) { // XOffset and YOffset are currently hardcoded values, but will represent camera offset combined with HUD offset Point tile = IsoToScreen(col, row, TileWidth / 2, TileHeight / 2, XOffset, YOffset); int x = tile.X; int y = tile.Y; spriteBatch.Draw(_tiles[i], new Rectangle(tile.X, tile.Y, TileWidth, TileHeight), Color.White); col++; if (col >= Columns) // Columns is the number of tiles in a single row { col = 0; row++; } } // Get selection overlay location (removed check if selection exists for simplicity sake) Point tile = IsoToScreen(_selectedTile.X, _selectedTile.Y, TileWidth / 2, TileHeight / 2, XOffset, YOffset); spriteBatch.Draw(_selectionTexture, new Rectangle(tile.X, tile.Y, TileWidth, TileHeight), Color.White); // End of draw code public Point IsoToScreen(int isoX, int isoY, int widthHalf, int heightHalf, int xOffset, int yOffset) { Point newPoint = new Point(); newPoint.X = widthHalf * (isoX + isoY) + xOffset; newPoint.Y = heightHalf * (-isoX + isoY) + yOffset; return newPoint; } This code draws the tiles correctly. Now I wanted to do picking to select the tiles. For this, I tried coming up with equations of my own (including reversing the drawing equation) and I tried multiple solutions I found on the internet and none of these solutions worked. Trying out lots of solutions, I came upon one that didn't work, but it seemed like an axis was just inverted. I fiddled around with the equations and somehow managed to get it to actually work (but have no idea why it works), but while it's close, it still doesn't work. I'm not really sure how to describe the behaviour, but it changes the selection at wrong places, while being fairly close (sometimes spot on, sometimes a tile off, I believe never more off than the adjacent tile). This is the code I have for getting which tile coordinates are selected: public Point? ScreenToIso(int screenX, int screenY, int tileHeight, int offsetX, int offsetY) { Point? newPoint = null; int nX = -1; int nY = -1; int tX = screenX - offsetX; int tY = screenY - offsetY; nX = -(tY - tX / 2) / tileHeight; nY = (tY + tX / 2) / tileHeight; newPoint = new Point(nX, nY); return newPoint; } I have no idea why this code is so close, especially considering it doesn't even use the tile width and all my attempts to write an equation myself or use a solution I googled failed. Also, I don't think this code accounts for the area outside the "tile" (the transparent part of the tile image), for which I intend to add a color map, but even if that's true, it's not the problem as the selection sometimes switches on approx 25% or 75% of width or height. I'm thinking I've stumbled upon a wrong path and need to backtrack, but at this point, I'm not sure what to do so I hope someone can shed some light on my error or point me to the right path. It may be worth mentioning that my goal is to not only pick the tile. Each main tile will be divided into 5x5 smaller tiles which won't be drawn seperately from the whole main tile, but they will need to be picked out. I think a color map of a main tile with different colors for different coordinates within the main tile should take care of that though, which would fall within using a color map for the main tile (for the transparent parts of the tile, meaning parts that possibly belong to other tiles).

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  • ROracle support for TimesTen In-Memory Database

    - by Sherry LaMonica
    Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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  • Performance triage

    - by Dave
    Folks often ask me how to approach a suspected performance issue. My personal strategy is informed by the fact that I work on concurrency issues. (When you have a hammer everything looks like a nail, but I'll try to keep this general). A good starting point is to ask yourself if the observed performance matches your expectations. Expectations might be derived from known system performance limits, prototypes, and other software or environments that are comparable to your particular system-under-test. Some simple comparisons and microbenchmarks can be useful at this stage. It's also useful to write some very simple programs to validate some of the reported or expected system limits. Can that disk controller really tolerate and sustain 500 reads per second? To reduce the number of confounding factors it's better to try to answer that question with a very simple targeted program. And finally, nothing beats having familiarity with the technologies that underlying your particular layer. On the topic of confounding factors, as our technology stacks become deeper and less transparent, we often find our own technology working against us in some unexpected way to choke performance rather than simply running into some fundamental system limit. A good example is the warm-up time needed by just-in-time compilers in Java Virtual Machines. I won't delve too far into that particular hole except to say that it's rare to find good benchmarks and methodology for java code. Another example is power management on x86. Power management is great, but it can take a while for the CPUs to throttle up from low(er) frequencies to full throttle. And while I love "turbo" mode, it makes benchmarking applications with multiple threads a chore as you have to remember to turn it off and then back on otherwise short single-threaded runs may look abnormally fast compared to runs with higher thread counts. In general for performance characterization I disable turbo mode and fix the power governor at "performance" state. Another source of complexity is the scheduler, which I've discussed in prior blog entries. Lets say I have a running application and I want to better understand its behavior and performance. We'll presume it's warmed up, is under load, and is an execution mode representative of what we think the norm would be. It should be in steady-state, if a steady-state mode even exists. On Solaris the very first thing I'll do is take a set of "pstack" samples. Pstack briefly stops the process and walks each of the stacks, reporting symbolic information (if available) for each frame. For Java, pstack has been augmented to understand java frames, and even report inlining. A few pstack samples can provide powerful insight into what's actually going on inside the program. You'll be able to see calling patterns, which threads are blocked on what system calls or synchronization constructs, memory allocation, etc. If your code is CPU-bound then you'll get a good sense where the cycles are being spent. (I should caution that normal C/C++ inlining can diffuse an otherwise "hot" method into other methods. This is a rare instance where pstack sampling might not immediately point to the key problem). At this point you'll need to reconcile what you're seeing with pstack and your mental model of what you think the program should be doing. They're often rather different. And generally if there's a key performance issue, you'll spot it with a moderate number of samples. I'll also use OS-level observability tools to lock for the existence of bottlenecks where threads contend for locks; other situations where threads are blocked; and the distribution of threads over the system. On Solaris some good tools are mpstat and too a lesser degree, vmstat. Try running "mpstat -a 5" in one window while the application program runs concurrently. One key measure is the voluntary context switch rate "vctx" or "csw" which reflects threads descheduling themselves. It's also good to look at the user; system; and idle CPU percentages. This can give a broad but useful understanding if your threads are mostly parked or mostly running. For instance if your program makes heavy use of malloc/free, then it might be the case you're contending on the central malloc lock in the default allocator. In that case you'd see malloc calling lock in the stack traces, observe a high csw/vctx rate as threads block for the malloc lock, and your "usr" time would be less than expected. Solaris dtrace is a wonderful and invaluable performance tool as well, but in a sense you have to frame and articulate a meaningful and specific question to get a useful answer, so I tend not to use it for first-order screening of problems. It's also most effective for OS and software-level performance issues as opposed to HW-level issues. For that reason I recommend mpstat & pstack as my the 1st step in performance triage. If some other OS-level issue is evident then it's good to switch to dtrace to drill more deeply into the problem. Only after I've ruled out OS-level issues do I switch to using hardware performance counters to look for architectural impediments.

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  • Visual Tree Enumeration

    - by codingbloke
    I feel compelled to post this blog because I find I’m repeatedly posting this same code in silverlight and windows-phone-7 answers in Stackoverflow. One common task that we feel we need to do is burrow into the visual tree in a Silverlight or Windows Phone 7 application (actually more recently I found myself doing this in WPF as well).  This allows access to details that aren’t exposed directly by some controls.  A good example of this sort of requirement is found in the “Restoring exact scroll position of a listbox in Windows Phone 7”  question on stackoverflow.  This required that the scroll position of the scroll viewer internal to a listbox be accessed. A caveat One caveat here is that we should seriously challenge the need for this burrowing since it may indicate that there is a design problem.  Burrowing into the visual tree or indeed burrowing out to containing ancestors could represent significant coupling between module boundaries and that generally isn’t a good idea. Why isn’t this idea just not cast aside as a no-no?  Well the whole concept of a “Templated Control”, which are in extensive use in these applications, opens the coupling between the content of the visual tree and the internal code of a control.   For example, I can completely change the appearance and positioning of elements that make up a ComboBox.  The ComboBox control relies on specific template parts having set names of a specified type being present in my template.  Rightly or wrongly this does kind of give license to writing code that has similar coupling. Hasn’t this been done already? Yes it has.  There are number of blogs already out there with similar solutions.  In fact if you are using Silverlight toolkit the VisualTreeExtensions class already provides this feature.  However I prefer my specific code because of the simplicity principle I hold to.  Only write the minimum code necessary to give all the features needed.  In this case I add just two extension methods Ancestors and Descendents, note I don’t bother with “Get” or “Visual” prefixes.  Also I haven’t added Parent or Children methods nor additional “AndSelf” methods because all but Children is achievable with the addition of some other Linq methods.  I decided to give Descendents an additional overload for depth hence a depth of 1 is equivalent to Children but this overload is a little more flexible than simply Children. So here is the code:- VisualTreeEnumeration public static class VisualTreeEnumeration {     public static IEnumerable<DependencyObject> Descendents(this DependencyObject root, int depth)     {         int count = VisualTreeHelper.GetChildrenCount(root);         for (int i = 0; i < count; i++)         {             var child = VisualTreeHelper.GetChild(root, i);             yield return child;             if (depth > 0)             {                 foreach (var descendent in Descendents(child, --depth))                     yield return descendent;             }         }     }     public static IEnumerable<DependencyObject> Descendents(this DependencyObject root)     {         return Descendents(root, Int32.MaxValue);     }     public static IEnumerable<DependencyObject> Ancestors(this DependencyObject root)     {         DependencyObject current = VisualTreeHelper.GetParent(root);         while (current != null)         {             yield return current;             current = VisualTreeHelper.GetParent(current);         }     } }   Usage examples The following are some examples of how to combine the above extension methods with Linq to generate the other axis scenarios that tree traversal code might require. Missing Axis Scenarios var parent = control.Ancestors().Take(1).FirstOrDefault(); var children = control.Descendents(1); var previousSiblings = control.Ancestors().Take(1)     .SelectMany(p => p.Descendents(1).TakeWhile(c => c != control)); var followingSiblings = control.Ancestors().Take(1)     .SelectMany(p => p.Descendents(1).SkipWhile(c => c != control).Skip(1)); var ancestorsAndSelf = Enumerable.Repeat((DependencyObject)control, 1)     .Concat(control.Ancestors()); var descendentsAndSelf = Enumerable.Repeat((DependencyObject)control, 1)     .Concat(control.Descendents()); You might ask why I don’t just include these in the VisualTreeEnumerator.  I don’t on the principle of only including code that is actually needed.  If you find that one or more of the above  is needed in your code then go ahead and create additional methods.  One of the downsides to Extension methods is that they can make finding the method you actually want in intellisense harder. Here are some real world usage scenarios for these methods:- Real World Scenarios //Gets the internal scrollviewer of a ListBox ScrollViewer sv = someListBox.Descendents().OfType<ScrollViewer>().FirstOrDefault(); // Get all text boxes in current UserControl:- var textBoxes = this.Descendents().OfType<TextBox>(); // All UIElement direct children of the layout root grid:- var topLevelElements = LayoutRoot.Descendents(0).OfType<UIElement>(); // Find the containing `ListBoxItem` for a UIElement:- var container = elem.Ancestors().OfType<ListBoxItem>().FirstOrDefault(); // Seek a button with the name "PinkElephants" even if outside of the current Namescope:- var pinkElephantsButton = this.Descendents()     .OfType<Button>()     .FirstOrDefault(b => b.Name == "PinkElephants"); //Clear all checkboxes with the name "Selector" in a Treeview foreach (CheckBox checkBox in elem.Descendents()     .OfType<CheckBox>().Where(c => c.Name == "Selector")) {     checkBox.IsChecked = false; }   The last couple of examples above demonstrate a common requirement of finding controls that have a specific name.  FindName will often not find these controls because they exist in a different namescope. Hope you find this useful, if not I’m just glad to be able to link to this blog in future stackoverflow answers.

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  • Breaking 1NF to model subset constraints. Does this sound sane?

    - by Chris Travers
    My first question here. Appologize if it is in the wrong forum but this seems pretty conceptual. I am looking at doing something that goes against conventional wisdom and want to get some feedback as to whether this is totally insane or will result in problems, so critique away! I am on PostgreSQL 9.1 but may be moving to 9.2 for this part of this project. To re-iterate: Does it seem sane to break 1NF in this way? I am not looking for debugging code so much as where people see problems that this might lead. The Problem In double entry accounting, financial transactions are journal entries with an arbitrary number of lines. Each line has either a left value (debit) or a right value (credit) which can be modelled as a single value with negatives as debits and positives as credits or vice versa. The sum of all debits and credits must equal zero (so if we go with a single amount field, sum(amount) must equal zero for each financial journal entry). SQL-based databases, pretty much required for this sort of work, have no way to express this sort of constraint natively and so any approach to enforcing it in the database seems rather complex. The Write Model The journal entries are append only. There is a possibility we will add a delete model but it will be subject to a different set of restrictions and so is not applicable here. If and when we allow deletes, we will probably do them using a simple ON DELETE CASCADE designation on the foreign key, and require that deletes go through a dedicated stored procedure which can enforce the other constraints. So inserts and selects have to be accommodated but updates and deletes do not for this task. My Proposed Solution My proposed solution is to break first normal form and model constraints on arrays of tuples, with a trigger that breaks the rows out into another table. CREATE TABLE journal_line ( entry_id bigserial primary key, account_id int not null references account(id), journal_entry_id bigint not null, -- adding references later amount numeric not null ); I would then add "table methods" to extract debits and credits for reporting purposes: CREATE OR REPLACE FUNCTION debits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount < 0 THEN $1.amount * -1 ELSE NULL END; $$; CREATE OR REPLACE FUNCTION credits(journal_line) RETURNS numeric LANGUAGE sql IMMUTABLE AS $$ SELECT CASE WHEN $1.amount > 0 THEN $1.amount ELSE NULL END; $$; Then the journal entry table (simplified for this example): CREATE TABLE journal_entry ( entry_id bigserial primary key, -- no natural keys :-( journal_id int not null references journal(id), date_posted date not null, reference text not null, description text not null, journal_lines journal_line[] not null ); Then a table method and and check constraints: CREATE OR REPLACE FUNCTION running_total(journal_entry) returns numeric language sql immutable as $$ SELECT sum(amount) FROM unnest($1.journal_lines); $$; ALTER TABLE journal_entry ADD CONSTRAINT CHECK (((journal_entry.running_total) = 0)); ALTER TABLE journal_line ADD FOREIGN KEY journal_entry_id REFERENCES journal_entry(entry_id); And finally we'd have a breakout trigger: CREATE OR REPLACE FUNCTION je_breakout() RETURNS TRIGGER LANGUAGE PLPGSQL AS $$ BEGIN IF TG_OP = 'INSERT' THEN INSERT INTO journal_line (journal_entry_id, account_id, amount) SELECT NEW.id, account_id, amount FROM unnest(NEW.journal_lines); RETURN NEW; ELSE RAISE EXCEPTION 'Operation Not Allowed'; END IF; END; $$; And finally CREATE TRIGGER AFTER INSERT OR UPDATE OR DELETE ON journal_entry FOR EACH ROW EXECUTE_PROCEDURE je_breaout(); Of course the example above is simplified. There will be a status table that will track approval status allowing for separation of duties, etc. However the goal here is to prevent unbalanced transactions. Any feedback? Does this sound entirely insane? Standard Solutions? In getting to this point I have to say I have looked at four different current ERP solutions to this problems: Represent every line item as a debit and a credit against different accounts. Use of foreign keys against the line item table to enforce an eventual running total of 0 Use of constraint triggers in PostgreSQL Forcing all validation here solely through the app logic. My concerns are that #1 is pretty limiting and very hard to audit internally. It's not programmer transparent and so it strikes me as being difficult to work with in the future. The second strikes me as being very complex and required a series of contraints and foreign keys against self to make work, and therefore it strikes me as complex, hard to sort out at least in my mind, and thus hard to work with. The fourth could be done as we force all access through stored procedures anyway and this is the most common solution (have the app total things up and throw an error otherwise). However, I think proof that a constraint is followed is superior to test cases, and so the question becomes whether this in fact generates insert anomilies rather than solving them. If this is a solved problem it isn't the case that everyone agrees on the solution....

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