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• Visual Studio 2010 Best Practices

  - by Etienne Tremblay

  I’d like to thank Packt for providing me with a review version of Visual Studio 2010 Best Practices eBook. In fairness I also know the author Peter having seen him speak at DevTeach on many occasions.  I started by looking at the table of content to see what this book was about, knowing that “best practices” is a real misnomer I wanted to see what they were.  I really like the fact that he starts the book by really saying they are not really best practices but actually recommend practices.  As a Team Foundation Server user I found that chapter 2 was more for the open source crowd and I really skimmed it.  The portion on Branching was well documented, although I’m not a fan of the testing branch myself, but the rest was right on. The section on merge remote changes (bring the outside to you) paradigm is really important and was touched on. Chapter 3 has good solid practices on low level constructs like generics and exceptions. Chapter 4 dives into architectural practices like decoupling, distributed architecture and data based architecture.  DTOs and ORMs are touched on briefly as is NoSQL. Chapter 5 is about deployment and is really a great primer on all the “packaging” technologies like Visual Studio Setup and Deployment (depreciated in 2012), Click Once and WIX the major player outside of commercial solutions.  This is a nice section on how to move from VSSD to WIX this is going to be important in the coming years due to the fact that VS 2012 doesn’t support VSSD. In chapter 6 we dive into automated testing practices, including test coverage, mocking, TDD, SpecDD and Continuous Testing.  Peter covers all those concepts really nicely albeit succinctly. Being a book on recommended practices I find this is really good. I really enjoyed chapter 7 that gave me a lot of great tips to enhance my Visual Studio “experience”.  Tips on organizing projects where good.  Also even though I knew about configurations I like that he put that in there so you can move all your settings to another machine, a lot of people don’t know about that. Quick find and Resharper are also briefly covered.  He touches on macros (depreciated in 2012).  Finally he touches on Continuous Integration a very important concept in today’s ALM landscape. Chapter 8 is all about Parallelization, threads, Async, division of labor, reactive extensions.  All those concepts are touched on and again generalized approaches to those modern problems are giving.       Chapter 9 goes into distributed apps, the most used and accepted practice in the industry for .NET projects the chapter tackles concepts like Scalability, Messaging and Cloud (the flavor of the month of distributed apps, although I think this will stick ;-)).  He also looks a protocols TCP/UDP and how to debug distributed apps.  He touches on logging and health monitoring. Chapter 10 tackles recommended practices for web services starting with implementing WCF services, which goes into all sort of goodness like how to host in IIS or self-host.  How to manual test WCF services, also a section on authentication and authorization.  ASP.NET Web services are also touched on in that chapter All in all a good read, nice tips and accepted practices.  I like the conciseness of the subjects and Peter touches on a lot of things in this book and uses a lot of the current technologies flavors to explain the concepts.   Cheers, ET

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• App Stores&ndash;In All Things, Its Quality Over Quantity

  - by D'Arcy Lussier

  Everybody has an opinion about Windows 8. People love it, people hate it, people are meh about it, people are apparently buying it from Microsoft stores in NYC as if it was water before a natural disaster…if there’s one thing that Microsoft product launches do well, its the ability to bring out strong emotional responses. Over at eweek.com, Don Reisinger wrote about 5 good and bad things about Windows 8. Yes, another opinion piece on WIndows 8. I figured since this one had good and bad it might be worthwhile to read. I then came across #10 on his list, and figured “What the hell…might as well post a bit of a rant on Windows 8 myself!” Here’s #10: 10. Bad: Too few apps Unfortunately, Microsoft wasn’t able to get too many developers to start producing applications for its Windows 8 Store. Microsoft hasn’t yet released official numbers, but some have said that the marketplace has less than 8,000 programs. Considering Apple’s App Store has 100 times that, it’s about time Microsoft starts leaning on developers to get more programs into its store. Believe me, Microsoft *has* been leaning on developers to get apps into the store. I’ve been asked at least 5 or 6 times from 5 or 6 different friends at Microsoft about whether I was going to write a Windows 8 app. I think Microsoft felt they had to try and address the number of apps available in their marketplace, since some people (like Don) would draw comparisons to the number of apps in the Apple marketplace. I feel for Microsoft in this, since the number of apps in a marketplace are an empty stat. Quality of Quantity I have an iPad that my family (wife, 10yo daughter, 3yo daughter) use. We all have our own apps installed on it. In addition, my wife has an iPhone 4S that she also installs apps on. As someone who gets asked by his kids often whether they can buy/download an app, the vast majority of the vast catalogue of iOS marketplace apps are crap! Do you realize how many “free” games are out there, only to really be not-free because you have to purchase in-game content to make the game actually playable? And how about searching – with such a vast array of apps and such high numbers of craptastic ones, trying to find something is incredibly difficult and can be frustrating. I would rather see that Microsoft has 8000 high quality apps in their store at launch, instead of 800000 that were mostly junk. Too Few Apps?! And seriously, 8000 is not a small number. How many iOS apps have I actually bought between the iPad and iPhone? I’ll be generous and say 30…heck, let’s round it up to 40. It’s not like I have 10,000 apps installed on my iPad, nor will that ever happen! So if people have, at the *launch* of a new platform ecosystem, EIGHT THOUSAND apps to choose from, I don’t see that as a fail at all! It should be noted that most of the most common apps (Netflix, Skype, etc.) are available for Windows 8 at launch – I guess I’ll have to wait a few weeks for My Pony Ranch and all its clones to start showing up; pity. Let’s Check Back in a Year So look, let’s check back in a year’s time and see what the app store looks like. My hope is that Microsoft doesn’t continue to push quantity over quality. Even knowing the optics that # of apps in the store carries and the pressure to catch Apple and Android marketplaces, I hope Microsoft avoids the scenario where there’s a good percentage of apps in the Windows Store that are utter rubbish and finding the gems will be cumbersome. But if that happens, we can thank guys like Dan who raised the false issue of app count at the launch for it.

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• Webcast Q&A: Demystifying External Authorization

  - by B Shashikumar

  Thanks to everyone who joined us on our webcast with SANS Institute on "Demystifying External Authorization". Also a special thanks to Tanya Baccam from SANS for sharing her experiences reviewing Oracle Entitlements Server. If you missed the webcast, you can catch a replay of the webcast here.  Here is a compilation of the slides that were used on today's webcast.  SANS Institute Product Review: Oracle Entitlements Server We have captured the Q&A from the webcast for those who couldn't attend. Q: Is Oracle ADF integrated with Oracle Entitlements Server (OES) ? A:  In Oracle Fusion Middleware 11g and later, Oracle ADF, Oracle WebCenter, Oracle SOA Suite and other middleware products are all built on Oracle Platform Security Services (OPSS). OPSS privodes many security functions like authentication, audit, credential stores, token validaiton, etc. OES is the authorization solution underlying OPSS. And OES 11g unifies different authorization mechanisms including Java2/ABAC/RBAC.  Q: Which portal frameworks support the use of OES policies for portal entitlement decisions? A:  Many portals including Oracle WebCenter 11g  run natively on top of OES. The authorization engine in WebCenter is OES. Besides, OES offers out of the box integration with Microsoft SharePoint. So SharePoint sites, sub sites, web parts, navigation items, document access control can all be secured with OES. Several other portals have also been secured with OES ex: IBM websphere portal Q:  How do we enforce Seperation of Duties (SoD) rules using OES (also how does that integrate with a product like OIA) ? A:  A product like OIM or OIA can be used to set up and govern SoD policies. OES enforces these policies at run time. Role mapping policies in OES can assign roles dynamically to users under certain conditions. So this makes it simple to enforce SoD policies inside an application at runtime. Q:  Our web application has objects like buttons, text fields, drop down lists etc. is there any ”autodiscovery” capability that allows me to use/see those web page objects so you can start building policies over those objects? or how does it work? A:  There ae few different options with OES. When you build an app, and make authorization calls with the app in the test environment, you can put OES in discovery mode and have OES register those authorization calls and decisions. Instead of doing  this after the fact, an application like Oracle iFlex has built-in UI controls where when the app is running, a script can intercept authorization calls and migrate those over to OES. And in Oracle ADF, a lot of resources are protected so pages, task flows and other resources be registered without OES knowing about them. Q: Does current Oracle Fusion application use OES ? The documentation does not seem to indicate it. A:  The current version of Fusion Apps is using a preview version of OES. Soon it will be repalced with OES 11g.  Q: Can OES secure mobile apps? A: Absolutely. Nowadays users are bringing their own devices such as a a smartphone or tablet to work. With the Oracle IDM platform, we can tie identity context into the access management stack. With OES we can make use of context to enforce authorization for users accessing apps from mobile devices. For example: we can take into account different elements like authentication scheme, location, device type etc and tie all that information into an authorization decision.  Q:  Does Oracle Entitlements Server (OES) have an ESAPI implementation? A:  OES is an authorization solution. ESAPI/OWASP is something we include in our platform security solution for all oracle products, not specifically in OES Q:  ESAPI has an authorization API. Can I use that API to access OES? A:  If the API supports an interface / sspi model that can be configured to invoke an external authz system through some mechanism then yes

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• Essential Links for the SharePoint Client Side Developer

  - by Mark Rackley

  Front End Developer? Client Side Developer? Middle Tier??? I’m covering all my bases.  Regardless, I’m sick and tired of Googling with Bing when I forget where information that I need often is located. I was getting ready to bookmark some of them when it hit me… “Hey Mark… (I don’t actually refer to myself in the third person), Why don’t you put the links in a blog so that it looks like you are being helpful!” I can’t tell you how many times I’ve had to go back to some of my old blogs to remember how I did something. Seriously people, you need to start a blog, it’s the best way to remember how the frick you got something to work… and it looks like you are being helpful when in reality you are just forgetful.  So… where was I? Oh yeah.. essential information that I’ve needed from time to time when I was not using Visual Studio. All of this info has come in handy from time to time. Know about these things and keep them in your tool belt, it’s amazing the stuff you can accomplish with just knowing where to look. What Why SPServices Widely used library written by Marc Anderson used to call SharePoint Web Services with jQuery jQuery For SPServices and other cool stuff Easy Tabs Essential tool for quick page enhancements. This widely used too from Christophe Humbert groups multiple web parts into one tabbed display. Very quick and easy way to get oohs and ahs from End Users. Convert Calculated Columns to HTML Also from Christophe, I use this script all the time to convert html in my calculated columns to actually display as html and not with the tags. Unlocking the Mysteries of Data View Web Part XSL Tags This blog series from Marc Anderson makes it very easy to understand what’s going on with all those weird xsl tags in your data view web parts. Essential to make those things do what you want them to do. Creating Parent / Child list relationships (2007) Creating Parent / Child list relationships (2010) By far my most viewed blog posts (tens and tens of thousands).  I have posts for both 2007 and 2010 that walk you through automatically setting the lookup id on a list to its “parent”. Set SharePoint Form fields using Query String Variables Also widely read, this one walks you through taking a variable from your Query String and set a form field to that value.   Hmmm… I KNOW there are more, but I’m tired and drawing a blank.  I’ll try to add them when I remember them (or need them again and think “Oh, I forgot to add that one”) But it’s a start, and please feel free to add your own in the comments… So, it’s YOUR turn to be helpful. What little tip or trick do you find yourself using ALL the time that you think everyone should know about??

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• Resolve SRs Faster Using RDA - Find the Right Profile

  - by Daniel Mortimer

  Introduction Remote Diagnostic Agent (RDA) is an excellent command-line data collection tool that can aid troubleshooting / problem solving. The tool covers the majority of Oracle's vast product range, and its data collection capability is comprehensive. RDA collects data about the operating system and environment, including environment variable, kernel settings network o/s performance o/s patches and much more the Oracle Products installed, including patches logs and debug metrics configuration and much more In effect, RDA can obtain a snapshot of an Oracle Product and its environment. Oracle Support encourages the use of RDA because it greatly reduces service request resolution time by minimizing the number of requests from Oracle Support for more information. RDA is designed to be as unobtrusive as possible; it does not modify systems in any way. It collects useful data for Oracle Support only and a security filter is provided if required. Find and Use the Right RDA Profile One problem of any tool / utility, which covers a large range of products, is knowing how to target it against only the products you wish to troubleshoot. RDA does not have a GUI. Nor does RDA have an intelligent mechanism for detecting and automatically collecting data only for those Oracle products installed. Instead, you have to tell RDA what to do. There is a mind boggling large number of RDA data collection modules which you can configure RDA to use. It is easier, however, to setup RDA to use a "Profile". A profile consists of a list of data collection modules and predefined settings. As such profiles can be used to diagnose a problem with a particular product or combination of products. How to run RDA with a profile? ( <rda> represents the command you selected to run RDA (for example, rda.pl, rda.cmd, rda.sh, and perl rda.pl).) 1. Use the embedded spreadsheet to find the RDA profile which is appropriate for your problem / chosen Oracle Fusion Middleware products. 2. Use the following command to perform the setup <rda> -S -p <profile_name>  3. Run the data collection <rda> Run the data collection. If you want to perform setup and run in one go, then use a command such as the following: <rda> -vnSCRP -p <profile name> For more information, refer to: Remote Diagnostic Agent (RDA) 4 - Profile Manual Pages [ID 391983.1] Additional Hints / Tips: 1. Be careful! Profile names are case sensitive.2. When profiles are not used, RDA considers all existing modules by default. For example, if you have downloaded RDA for the first time and run the command <rda> -S you will see prompts for every RDA collection module many of which will be of no interest to you. Also, you may, in your haste to work through all the questions, forget to say "Yes" to the collection of data that is pertinent to your particular problem or product. Profiles avoid such tedium and help ensure the right data is collected at the first time of asking.

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• IE9 and the Mystery of the Broken Video Tag

  - by David Wesst

  I was very excited when Microsoft released the Internet Explorer 9 Release Candidate. As far as I was concerned, this was another nail in the coffin for IE6 and step in the right direction for us .NET web developers as our base camp was finally starting to support the latest and greatest future-web standards. Unfortunately, my celebration was short lived as I soon hit a snag while loading up an HTML5 site I was building in Visual Studio 2010. The Mystery After updating Internet Explorer, I ran my HTML5 site that had the oh-so-lovely HTML5 video tag showing a video. Even though this worked in IE9 Beta, it appeared that IE9 RC could not load the same file. I figured that it was the video codec. Maybe IE9 RC no longer supported the video codec I used to encode my video. Here's the code I used: <video width="854" height="480" id="myOtherVideo" autoplay="" controls=""> <source src="/DemoSite1/Media/big_buck_bunny.mp4"/> <div> <p>Your browser does not support HTML5 Video.</p> </div> </video> As you can see from the code, I had the "fail-safe" code inside the video tag. The idea there being that if the video tag, or the video files themselves, are not supported by the browser my video should fail gracefully. What was even more strange was the fact that it worked in all the other HTML5 browsers that supported video. The Investigation Whoa! DJ stop the music. How can any of that make sense? Would the IE team really take such huge strides forward only to forget to include a feature that was already in the beta? I don't think so. I did plenty of searching on the web and asking around on the web, but could not seem to find anyone else having the same problem. Eventually I came across this post talking about declaring the MIME type in the .htaccess file. That got me thinking: does my web server support the video MIME type? I was using VS2010, so how do I know what kind of MIME types are supported by default? Still, my page hosted in Cassini (the web development server in VS2010) works on the other browsers. Why wouldn't it work with IE9 RC? To answer that, it was time to open up the upgraded toolbox known as the Developer's Tools in IE9 and use the new Network Tab. The Conclusion If you take a closer look at the results displayed from the Network tab, you can see that IE9 RC has interpreted the video file as text/html rather than video/mp4. To make this work, I decided to use IIS to debug my HTML5 web application by setting the web project's properties. Then, I added the MIME types that I want to support (i.e. video/mp4, video/ogg, video/webm). Et voila! The Mystery of the Broken Video Tag is solved. After Thoughts After solving the mystery, I still had the question about why my site worked in Chrome, Safari, and Firefox 3.6. After asking around, the best answer that I received was from my colleague Tyler Doerksen. He said that IE9 likely depends on the server telling it what kind of file it is downloading rather than trying to read the metadata about the data it is trying to download before doing anything. I have no facts to back this up, but it makes sense to me. In a browser war where milliseconds can make your browser fall back a few places in the race for supremacy, maybe the IE team opted to depend on the server knowing what kind of content it is serving up. Makes sense to me. In any case, that is just an educated guess. If you have any comments, feel free to post on them below. This post also appears at http://david.wes.st

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• Removing Barriers to Create Effective Data Models

  After years of creating and maintaining data models, I have started to notice common barriers that decrease the accuracy and usefulness of models. In my opinion, the main causes of these barriers are the lack of knowledge and communication from within a company. The lack of knowledge in regards to data models or data modeling can take many forms. Company Culture Knowledge Whether documented or undocumented, existing business rules of a company can affect how data is modeled. For example, if a company only allows 1 assigned person per customer to be able to manipulate a customer’s record then then a data model that includes an associated table that joins customers and employee’s would be unneeded because that would allow for the possibility of multiple employees to handle a customer because of the potential for a many to many relationship between Customers and Employees. Technical Knowledge Depending on the data modeler’s proficiency in modeling data they can inadvertently cause issues and/or complications with a design without even noticing. It is important that companies share data modeling responsibilities so that the models are developed from multiple perspectives of a system, company and the original problem.  In addition, the tools that a company selects to create data models can also affect the accuracy of the model if designer are not familiar with the tools or the tools are too complex to use for the designer. Existing System Knowledge In order for a data modeler to model data for an existing system so that new changes can be applied to a system then they need to at least know the basic concepts of a system so that they can work within it. This will promote reusability of data and prevent the chance of duplicating data. Project Knowledge This should be pretty obvious, but it is very hard to create an accurate data model without knowing what data needs to be modeled. I have always found it strange that I have been asked to start modeling data prior to a client formalizing any requirements. Usually when this happens I have to make several iterations to a model, and the client still does not know exactly what they want.  In addition additional issues can arise when certain stakeholders of a project are not consulted prior to the design or after the project is over because it can cause miss understandings and confusion by the end user as well as possibly not solving the original problem for which a project is intended to solve. One common thread between each type of knowledge is that they can all be avoided through the use of good communication. For example, if a modeler is new to a company then they should ask older employees about any business specific rules that may be documented or undocumented that must be applied to projects in general. Furthermore, if a modeler is not really familiar with a specific data modeling software then they need to speak up and ask for help form other employees or their manager. This will not only help the modeler in the project, but also help them in future projects that they do for the company. Additionally, if a project is not clearly defined prior to a data modeler being assigned the modeling project then it is their responsibility to communicate with the other stakeholders to clarify any part of a project that is unclear so that the data model that is created is accurately aligned with a project.

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• Scenarios for Throwing Exceptions

  - by Joe Mayo

  I recently came across a situation where someone had an opinion that differed from mine of when an exception should be thrown. This particular case was an issue opened on LINQ to Twitter for an Exception on EndSession.  The premise of the issue was that the poster didn’t feel an exception should be raised, regardless of authentication status.  As first, this sounded like a valid point.  However, I went back to review my code and decided not to make any changes. Here's my rationale: 1. The exception doesn’t occur if the user is authenticated when EndAccountSession is called. 2. The exception does occur if the user is not authenticated when EndAccountSession is called. 3. The exception represents the fact that EndAccountSession is not able to fulfill its intended purpose - to end the session.  If a session never existed, then it would not be possible to perform the requested action.  Therefore, an exception is appropriate. To help illustrate how to handle this situation, I've modified the following code in Program.cs in the LinqToTwitterDemo project to illustrate the situation: static void EndSession(ITwitterAuthorizer auth) { using (var twitterCtx = new TwitterContext(auth, "https://api.twitter.com/1/", "https://search.twitter.com/")) { try { //Log twitterCtx.Log = Console.Out; var status = twitterCtx.EndAccountSession(); Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } catch (TwitterQueryException tqe) { var webEx = tqe.InnerException as WebException; if (webEx != null) { var webResp = webEx.Response as HttpWebResponse; if (webResp != null && webResp.StatusCode == HttpStatusCode.Unauthorized) Console.WriteLine("Twitter didn't recognize you as having been logged in. Therefore, your request to end session is illogical.\n"); } var status = tqe.Response; Console.WriteLine("Request: {0}, Error: {1}" , status.Request , status.Error); } } } As expected, LINQ to Twitter wraps the exception in a TwitterQueryException as the InnerException.  The TwitterQueryException serves a very useful purpose through it's Response property.  Notice in the example above that the response has Request and Error proprieties.  These properties correspond to the information that Twitter returns as part of it's response payload.  This is often useful while debugging to help you understand why Twitter was unable to perform the  requested action.  Other times, it's cryptic, but that's another story.  At least you have some way of knowing in your code how to anticipate and handle these situations, along with having extra information to debug with. To sum things up, there are two points to make: when and why an exception should be raised and when to wrap and re-throw an exception in a custom exception type. I felt it was necessary to allow the exception to be raised because the called method was unable to perform the task it was designed for.  I also felt that it is inappropriate for a general library to do anything with exceptions because that could potentially hide a problem from the caller.  A related point is that it should be the exclusive decision of the application that uses the library on what to do with an exception.  Another aspect of this situation is that I wrapped the exception in a custom exception and re-threw.  This is a tough call because I don’t want to hide any stack trace information.  However, the need to make the exception more meaningful by including vital information returned from Twitter swayed me in the direction to design an interface that was as helpful as possible to library consumers.  As shown in the code above, you can dig into the exception and pull out a lot of good information, such as the fact that the underlying HTTP response was a 401 Unauthorized.  In all, trade-offs are seldom perfect for all cases, but combining the fact that the method was unable to perform its intended function, this is a library, and the extra information can be more helpful, it seemed to be the better design. @JoeMayo

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• Where Have All the Ugly Forms Gone? Users and ADF Took Care Of It

  - by ultan o'broin

  Sometimes I hear that our application demos are a bit too "cutsey" and that we never talk about with any user roles that have lots of data entry as a requirement. Some (no names) consider those old clunker forms, with the myriad rows of fields, to be super-productive for data clerks. We do have such roles covered in Oracle Fusion Applications for sure. But consider what is really the issue here: productivity. Check out how the Oracle Fusion Financials Applications User Experience team went about designing for productivity when receiving and entering invoice data, for example. See how Fusion Financials caters so well for input and control of data? Central to all this is knowing the users and how they work: what tasks do they need to perform, and when. Read more about Fusion Financials productivity in the white paper, Get It Done Fast, Get It Done Right: The Oracle Fusion Financials User Experience. Now and then, I see forms that weren't designed for end user activity at all. Instead, they were designed by developers or by the IT department around the database schema. Forms with literally dozens of fields on the same page, sometimes. Forms that give the impression there was only task involved, when there may have been several. At times, completing one of these huge forms accurately became so tedious that, under pressure, it made more sense for the user to complete it quickly as possible and then let somebody else check it for accuracy and fill in the gaps from data emailed along in spreadsheet form. Data accuracy is critical in our business. Not good. Not efficient. Not productive. So here are a few basics on forms design for data entry-type user roles. A great place for developers to start exploring what is possible with forms layout is the Rich Client User Experience (RCUX) guidance on Form Layout, using ADF components. User-Centered Forms Design Considerations The starting point--something you must always keep in mind with your own design--is design for the end user. Find a representative end user, and keep that user engaged throughout the design, deployment, and test process. Consider these points in user testing those forms: Are there automated or technical solutions to entering the data that avoid manual input in the first place? For example, imports, uploads, OCR, whatever. Some day we will be able to tell Siri to do it, but leave that for now. Design your form to reflect the task involved (i.e., the business process) and not the database schema. On the form, group like fields together, logically. Eliminate duplicate data entry or prepopulate from previous data entry. Allow users to complete fields in the order they wish (i.e., no interdependency). Allow for tabbing between fields (keyboard is faster than mouse), so know how the browser supports this (see that RCUX guideline). Allow for final validation at the page level not at field-level entry. Way better for heads-down users. For example, ADF messages allow you to see a list of all validation errors on a page on a final submit or navigation action and to easily navigate to the point of error. Better still, be error tolerant. Allow users to enter data in formats they comfortable with. Bind any relevant user preference setting to the input format allowed (for example, the locale date format). Explore what data entry conversion can do for you automatically too (see the ADF converter demos, convenience patterns can also be written). Only ask for data input when it's needed. Get rid of, or hide optional fields. Cut down on the number of mandatory fields, and mark them clearly (use a *). Clearly label the fields in plain language. I am sure you may have a few more tips on forms design for data entry users. Remember the user before finding the comments.

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• Non use of persisted data

  - by Dave Ballantyne

  Working at a client site, that in itself is good to say, I ran into a set of circumstances that made me ponder, and appreciate, the optimizer engine a bit more. Working on optimizing a stored procedure, I found a piece of code similar to : select BillToAddressID, Rowguid, dbo.udfCleanGuid(rowguid) from sales.salesorderheaderwhere BillToAddressID = 985 A lovely scalar UDF was being used,  in actuality it was used as part of the WHERE clause but simplified here.  Normally I would use an inline table valued function here, but in this case it wasn't a good option. So this seemed like a pretty good case to use a persisted column to improve performance. The supporting index was already defined as create index idxBill on sales.salesorderheader(BillToAddressID) include (rowguid) and the function code is Create Function udfCleanGuid(@GUID uniqueidentifier)returns varchar(255)with schemabindingasbegin Declare @RetStr varchar(255) Select @RetStr=CAST(@Guid as varchar(255)) Select @RetStr=REPLACE(@Retstr,'-','') return @RetStrend Executing the Select statement produced a plan of : Nothing surprising, a seek to find the data and compute scalar to execute the UDF. Lets get optimizing and remove the UDF with a persisted column Alter table sales.salesorderheaderadd CleanedGuid as dbo.udfCleanGuid(rowguid)PERSISTED A subtle change to the SELECT statement… select BillToAddressID,CleanedGuid from sales.salesorderheaderwhere BillToAddressID = 985 and our new optimized plan looks like… Not a lot different from before!  We are using persisted data on our table, where is the lookup to fetch it ?  It didnt happen,  it was recalculated.  Looking at the properties of the relevant Compute Scalar would confirm this ,  but a more graphic example would be shown in the profiler SP:StatementCompleted event. Why did the lookup happen ? Remember the index definition,  it has included the original guid to avoid the lookup.  The optimizer knows this column will be passed into the UDF, run through its logic and decided that to recalculate is cheaper than the lookup.  That may or may not be the case in actuality,  the optimizer has no idea of the real cost of a scalar udf.  IMO the default cost of a scalar UDF should be seen as a lot higher than it is, since they are invariably higher. Knowing this, how do we avoid the function call?  Dropping the guid from the index is not an option, there may be other code reliant on it.   We are left with only one real option,  add the persisted column into the index. drop index Sales.SalesOrderHeader.idxBillgocreate index idxBill on sales.salesorderheader(BillToAddressID) include (rowguid,cleanedguid) Now if we repeat the statement select BillToAddressID,CleanedGuid from sales.salesorderheaderwhere BillToAddressID = 985 We still have a compute scalar operator, but this time it wasnt used to recalculate the persisted data.  This can be confirmed with profiler again. The takeaway here is,  just because you have persisted data dont automatically assumed that it is being used.

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• Stale statistics on a newly created temporary table in a stored procedure can lead to poor performance

  - by sqlworkshops

  When you create a temporary table you expect a new table with no past history (statistics based on past existence), this is not true if you have less than 6 updates to the temporary table. This might lead to poor performance of queries which are sensitive to the content of temporary tables.I was optimizing SQL Server Performance at one of my customers who provides search functionality on their website. They use stored procedure with temporary table for the search. The performance of the search depended on who searched what in the past, option (recompile) by itself had no effect. Sometimes a simple search led to timeout because of non-optimal plan usage due to this behavior. This is not a plan caching issue rather temporary table statistics caching issue, which was part of the temporary object caching feature that was introduced in SQL Server 2005 and is also present in SQL Server 2008 and SQL Server 2012. In this customer case we implemented a workaround to avoid this issue (see below for example for workarounds).When temporary tables are cached, the statistics are not newly created rather cached from the past and updated based on automatic update statistics threshold. Caching temporary tables/objects is good for performance, but caching stale statistics from the past is not optimal.We can work around this issue by disabling temporary table caching by explicitly executing a DDL statement on the temporary table. One possibility is to execute an alter table statement, but this can lead to duplicate constraint name error on concurrent stored procedure execution. The other way to work around this is to create an index.I think there might be many customers in such a situation without knowing that stale statistics are being cached along with temporary table leading to poor performance.Ideal solution is to have more aggressive statistics update when the temporary table has less number of rows when temporary table caching is used. I will open a connect item to report this issue.Meanwhile you can mitigate the issue by creating an index on the temporary table. You can monitor active temporary tables using Windows Server Performance Monitor counter: SQL Server: General Statistics->Active Temp Tables. The script to understand the issue and the workaround is listed below:set nocount onset statistics time offset statistics io offdrop table tab7gocreate table tab7 (c1 int primary key clustered, c2 int, c3 char(200))gocreate index test on tab7(c2, c1, c3)gobegin trandeclare @i intset @i = 1while @i <= 50000begininsert into tab7 values (@i, 1, ‘a’)set @i = @i + 1endcommit trangoinsert into tab7 values (50001, 1, ‘a’)gocheckpointgodrop proc test_slowgocreate proc test_slow @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_slow 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'exec test_slow 2godrop proc test_with_recompilegocreate proc test_with_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_recompile 1godbcc dropcleanbuffersgo–high reads that are not expected for parameter ’2'–low reads on 3rd execution as expected for parameter ’2'exec test_with_recompile 2godrop proc test_with_alter_table_recompilegocreate proc test_with_alter_table_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create a constraint–but this might lead to duplicate constraint name error on concurrent usagealter table #temp1 add constraint test123 unique(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgodbcc dropcleanbuffersset statistics time onset statistics io ongo–high reads as expected for parameter ’1'exec test_with_alter_table_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_alter_table_recompile 2godrop proc test_with_index_recompilegocreate proc test_with_index_recompile @i intasbegindeclare @j intcreate table #temp1 (c1 int primary key)–to avoid caching of temporary tables one can create an indexcreate index test on #temp1(c1)insert into #temp1 (c1) select @iselect @j = t7.c1 from tab7 t7 inner join #temp1 t on (t7.c2 = t.c1)option (recompile)endgoset statistics time onset statistics io ondbcc dropcleanbuffersgo–high reads as expected for parameter ’1'exec test_with_index_recompile 1godbcc dropcleanbuffersgo–low reads as expected for parameter ’2'exec test_with_index_recompile 2go

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• Is it bad practice to make an iterator that is aware of its own end

  - by aaronman

  For some background of why I am asking this question here is an example. In python the method chain chains an arbitrary number of ranges together and makes them into one without making copies. Here is a link in case you don't understand it. I decided I would implement chain in c++ using variadic templates. As far as I can tell the only way to make an iterator for chain that will successfully go to the next container is for each iterator to to know about the end of the container (I thought of a sort of hack in where when != is called against the end it will know to go to the next container, but the first way seemed easier and safer and more versatile). My question is if there is anything inherently wrong with an iterator knowing about its own end, my code is in c++ but this can be language agnostic since many languages have iterators. #ifndef CHAIN_HPP #define CHAIN_HPP #include "iterator_range.hpp" namespace iter { template <typename ... Containers> struct chain_iter; template <typename Container> struct chain_iter<Container> { private: using Iterator = decltype(((Container*)nullptr)->begin()); Iterator begin; const Iterator end;//never really used but kept it for consistency public: chain_iter(Container & container, bool is_end=false) : begin(container.begin()),end(container.end()) { if(is_end) begin = container.end(); } chain_iter & operator++() { ++begin; return *this; } auto operator*()->decltype(*begin) { return *begin; } bool operator!=(const chain_iter & rhs) const{ return this->begin != rhs.begin; } }; template <typename Container, typename ... Containers> struct chain_iter<Container,Containers...> { private: using Iterator = decltype(((Container*)nullptr)->begin()); Iterator begin; const Iterator end; bool end_reached = false; chain_iter<Containers...> next_iter; public: chain_iter(Container & container, Containers& ... rest, bool is_end=false) : begin(container.begin()), end(container.end()), next_iter(rest...,is_end) { if(is_end) begin = container.end(); } chain_iter & operator++() { if (begin == end) { ++next_iter; } else { ++begin; } return *this; } auto operator*()->decltype(*begin) { if (begin == end) { return *next_iter; } else { return *begin; } } bool operator !=(const chain_iter & rhs) const { if (begin == end) { return this->next_iter != rhs.next_iter; } else return this->begin != rhs.begin; } }; template <typename ... Containers> iterator_range<chain_iter<Containers...>> chain(Containers& ... containers) { auto begin = chain_iter<Containers...>(containers...); auto end = chain_iter<Containers...>(containers...,true); return iterator_range<chain_iter<Containers...>>(begin,end); } } #endif //CHAIN_HPP

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• Know your Data Lineage

  - by Simon Elliston Ball

  An academic paper without the footnotes isn’t an academic paper. Journalists wouldn’t base a news article on facts that they can’t verify. So why would anyone publish reports without being able to say where the data has come from and be confident of its quality, in other words, without knowing its lineage. (sometimes referred to as ‘provenance’ or ‘pedigree’) The number and variety of data sources, both traditional and new, increases inexorably. Data comes clean or dirty, processed or raw, unimpeachable or entirely fabricated. On its journey to our report, from its source, the data can travel through a network of interconnected pipes, passing through numerous distinct systems, each managed by different people. At each point along the pipeline, it can be changed, filtered, aggregated and combined. When the data finally emerges, how can we be sure that it is right? How can we be certain that no part of the data collection was based on incorrect assumptions, that key data points haven’t been left out, or that the sources are good? Even when we’re using data science to give us an approximate or probable answer, we cannot have any confidence in the results without confidence in the data from which it came. You need to know what has been done to your data, where it came from, and who is responsible for each stage of the analysis. This information represents your data lineage; it is your stack-trace. If you’re an analyst, suspicious of a number, it tells you why the number is there and how it got there. If you’re a developer, working on a pipeline, it provides the context you need to track down the bug. If you’re a manager, or an auditor, it lets you know the right things are being done. Lineage tracking is part of good data governance. Most audit and lineage systems require you to buy into their whole structure. If you are using Hadoop for your data storage and processing, then tools like Falcon allow you to track lineage, as long as you are using Falcon to write and run the pipeline. It can mean learning a new way of running your jobs (or using some sort of proxy), and even a distinct way of writing your queries. Other Hadoop tools provide a lot of operational and audit information, spread throughout the many logs produced by Hive, Sqoop, MapReduce and all the various moving parts that make up the eco-system. To get a full picture of what’s going on in your Hadoop system you need to capture both Falcon lineage and the data-exhaust of other tools that Falcon can’t orchestrate. However, the problem is bigger even that that. Often, Hadoop is just one piece in a larger processing workflow. The next step of the challenge is how you bind together the lineage metadata describing what happened before and after Hadoop, where ‘after’ could be  a data analysis environment like R, an application, or even directly into an end-user tool such as Tableau or Excel. One possibility is to push as much as you can of your key analytics into Hadoop, but would you give up the power, and familiarity of your existing tools in return for a reliable way of tracking lineage? Lineage and auditing should work consistently, automatically and quietly, allowing users to access their data with any tool they require to use. The real solution, therefore, is to create a consistent method by which to bring lineage data from these data various disparate sources into the data analysis platform that you use, rather than being forced to use the tool that manages the pipeline for the lineage and a different tool for the data analysis. The key is to keep your logs, keep your audit data, from every source, bring them together and use the data analysis tools to trace the paths from raw data to the answer that data analysis provides.

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• Learn Many Languages

  - by Jeff Foster

  My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

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• Top Three Reasons to Move to the Cloud Before Your Next Upgrade

  - by yaldahhakim

  Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";} 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-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Calibri","sans-serif";} 1) Reduced Cost - During major upgrades, most organizations typically need to replace or invest in extra hardware and other IT resources to support the upgrade. With the Cloud, this can become more of an Op-ex discussion. The flexibility and scalability of the cloud also allows for new business solution to be set up more quickly with the ability to scale IT resources to closely map to changing business requirements. . This enables more and faster innovation because you are spending money to focus on core business initiatives instead of setting up complex environments. 2) Reduced Risk- This is especially true when you are working with a cloud provider that possesses substantial in-house expertise. Oracle Managed Cloud Services has been hosting and managing customer’s business applications for over a decade and has help hundreds of customers upgrade and adopt new technologies faster and better. Customer have access to over 15,000 Oracle experts in operation centers around the world that can work around the clock and have direct access Oracle Development to optimize our customers’ upgrade experience. 3) Reduced Downtime - Whether a customer is looking to upgrade their E-Business Suite, PeopleSoft, JD-Edwards, or Fusion applications, we’ve developed standardized best practices and tools across the technology stack to accelerate the upgrade and migration with substantially reduced timelines and risk. And because the process is repeatable, customer stay more current on the latest releases, continuously taking advantage of the newest innovations – without the headache.. By leveraging the economies and expertise of scale that belong to Oracle, you can sleep better at night knowing that your next major application upgrade is taken care of. Check out the video of this Managed Cloud Services customer to learn more about their experience.

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• When things go awry

  - by Phil Factor

  The moment the Entrepreneur opened his mouth on prime-time national TV, spelled out the URL and waxed big on how exciting ‘his’ new website was, I knew I was in for a busy night. I’d designed and built it. All at once, half a million people tried to log into the website. Although all my stress-testing paid off, I have to admit that the network locked up tight long before there was any danger of a database or website problem. Soon afterwards, the Entrepreneur and the Big Boss were there in the autopsy meeting. We picked through all our systems in detail to see how they’d borne the unexpected strain. Mercifully, in view of the sour mood of the Big Boss, it turned out that the only thing we could have done better was buy a bigger pipe to and from the internet. We’d specified that ‘big pipe’ when designing the system. The Big Boss had then railed at the cost and so we’d subsequently compromised. I felt that my design decisions were vindicated. The Big Boss brooded for a while. Then he made the significant comment: “What really ****** me off is the fact that, for ten minutes, we couldn’t take people’s money.” At that point I stopped feeling smug. Had the internet connection been better, the system would have reached its limit and failed rather precipitously, and that wasn’t what he wanted. Then it occurred to me that what had gummed up the connection was all those images on the site, that had made it so impressive for the visitors. If there had been a way to automatically pare down the site to the bare essentials under stress… Hmm. I began to consider disaster-recovery in the broadest sense – maintaining a service in spite of unusual or unexpected events. What he said makes a lot of sense: sacrifice whatever isn’t essential to keep the core service running when we approach the capacity limits. Maybe in IT we should borrow (or revive) the business concept of the ‘Skeleton service’, maintaining only the priority parts under stress, using a process that is well-prepared and carefully rehearsed. How might this work? Whatever the event we have to prepare for, it is all about understanding the priorities; knowing what one can dispense with when the going gets tough. In the event of database disaster, it’s much faster to deploy a skeletal system with only the essential data than to restore the entire system, though there would have to be a reconciliation process to update the revived database retrospectively, once the emergency was over. It isn’t just the database that could be designed for resilience. One could prepare for unusually high traffic in a website by designing a system that degraded gradually to a ‘skeletal’ site, one that maintained the commercial essentials without fat images, JavaScript libraries and razzmatazz. This is all what the Big Boss scathingly called ‘a mere technicality’. It seems to me that what is needed first is a culture of application and database design which acknowledges that we live in a very imperfect world, and react accordingly when things go awry.

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• D&rsquo;Arcy&rsquo;s Book Club - The New Strategic Selling

  - by D'Arcy Lussier

  The New Strategic Selling Miller and Heiman Amazon.ca Amazon.com Chapters Everybody is a salesmen. Every day, without knowing it, we sell something to someone. Now, the typical vision people think of when they hear the word “sales” is the sleazy used car salesperson who does whatever they can to get you to buy the clunker on their lot. But selling is not an action tied to money and products. Selling is about convincing people to see your point of view and act on it. If you want your company to cover a trip to a conference, you may have to sell the idea to your boss. If you want to buy that new big screen TV, you have to sell the idea to your significant other. If you want to go on a weekend fishing trip with the boys you might be called in to help sell the idea to your buddies wife. We all sell, but we don’t all sell very well. So enter The New Strategic Selling, a book based on the sales course put on by the Miller-Heiman group. In fact, this isn’t really a “New” strategy to selling as its been around for a number of years. But the concepts they present, the ideas about selling, these are still very radical based on what most of us have experienced. Gone are the high pressure, win at all cost, GlenGarry-GlenRoss style of sales…instead the book presents a framework to switch to need-based selling. It’s the idea that instead of going in raving about a product or service, you build a relationship where the buyer expresses what their needs are and your response is to present a solution that best fits that need. Instead of focussing on the amount of money you can squeeze out of a client, you focus on whether everyone wins, that they receive win-results from the engagement, that repeat business is developed over time delivering value over and over again. The great thing about the book is that what it teaches…things like how to identify different buying influencers, how to prepare for meetings, techniques to solicit information about what the buyer is really thinking/feeling…these things are entirely applicable in *any* situation that you need to sell to someone…and remember: selling is convincing people to see your point of view and act on it. So that new big screen TV you want to buy but need to convince your wife on? This book can help you. That training opportunity you want your company to send you on? This book can help you. The upgrade to your community park that you want to lobby the local civic authorities for? This book can help you. The book is a bit wordy. I found that the length could have been reduced and the points still have gotten across. That’s really the only knock that I have though; the insight that it provides is so worthwhile that having to chew through extra words is well worth it. You definitely don’t have to be a professional salesperson to benefit from this book. Rating: 4/5

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• What Counts For a DBA – Depth

  - by Louis Davidson

  SQL Server offers very simple interfaces to many of its features. Most people could open up SSMS, connect to a server, write a simple query and see the results. Even several of the core DBA tasks are deceptively straightforward. It doesn’t take a rocket scientist to perform a basic database backup or run a trace (even using the newfangled Extended Events!). However, appearances can be deceptive, and often times it is really important that a DBA understands not just the basics of how to perform a task, but why we do a task, and how that task works. As an analogy, consider a child walking into a darkened room. Most would know that they need to turn on the light, and how to do it, so they flick the switch. But what happens if light fails to shine forth. Most would immediately tell you that you need to consider changing the light bulb. So you hop in the car and take them to the local home store and instruct them to buy a replacement. Confronted with a 40 foot display of light bulbs, how will they decide which of the hundreds of types of bulbs, of different types, fittings, shapes, colors, power and efficiency ratings, is the right choice? Obviously the main lesson the child is going to learn this day is how to use their cell phone as a flashlight so they don’t have to ask for help the next time. Likewise, when the metaphorical toddlers who use your database server have issues, they will instinctively know something is wrong, and may even have some idea what caused it, but will have no depth of knowledge to figure out the right solution. That is where the DBA comes in and attempts to save the day. However, when one looks beneath the shiny UI, SQL Server has its own “40 foot display of light bulbs”, in the form of the tremendous number of tools and the often-bewildering amount of information they can present to the DBA, to help us find issues. Unfortunately, resorting to guesswork, to trying different “bulbs” over and over, hoping to stumble on the answer. This is where the right depth of knowledge goes a long way. If we need to write a SELECT statement, then knowing the syntax and where to find the data is not enough. Knowledge of indexes and query plans is essential. Without it, we might hit on a query that “works”, but we are basically still a user, not a programmer, because we have no real control over our platform. Is that level of knowledge deep enough? Probably not, since knowledge of the underlying metadata and structures would be very useful in helping us make sense of any query plan. Understanding the structure of an index makes the “key lookup” operator not sound like what you do when someone tapes your car key to the ceiling. So is even this level of understanding deep enough? Do we need to understand the memory architecture used to process the query? It might be a comforting level of knowledge, and will doubtless come in handy at some point, but is not strictly necessary in most cases. Beyond that lies (more or less) full knowledge of SQL language and the intricacies of every step the SQL Server engine takes to process our query. My personal theory is that, as a professional, our knowledge of a given task should extend, at a minimum, one level deeper than is strictly necessary to perform the task. Anything deeper can be left to the ridiculously smart, or obsessive, or both. As an example. tasked with storing an integer value between 0 and 99999999, it’s essential that I know that choosing an Integer over Decimal(8,0) will likely offer performance benefits. It is then useful that I also understand the value of adding a CHECK constraint, to make sure the values are valid to the desired range; and comforting that I know a little about the underlying processors, registers and computer math. Anything further, I leave to the likes of Joe Chang, whose recent blog post on the topic offers depth by the bucketful!  

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• Come up with a real-world problem in which only the best solution will do (a problem from Introduction to algorithms) [closed]

  - by Mike

  EDITED (I realized that the question certainly needs a context) The problem 1.1-5 in the book of Thomas Cormen et al Introduction to algorithms is: "Come up with a real-world problem in which only the best solution will do. Then come up with one in which a solution that is “approximately” the best is good enough." I'm interested in its first statement. And (from my understanding) it is asked to name a real-world problem where only the exact solution will work as opposed to a real-world problem where good-enough solution will be ok. So what is the difference between the exact and good enough solution. Consider some physics problem for example the simulation of the fulid flow in the permeable medium. To make this simulation happen some simplyfing assumptions have to be made when deriving a mathematical model. Otherwise the model becomes at least complex and unsolvable. Virtually any particle in the universe has its influence on the fluid flow. But not all particles are equal. Those that form the permeable medium are much more influental than the ones located light years away. Then when the mathematical model needs to be solved an exact solution can rarely be found unless the mathematical model is simple enough (wich probably means the model isn't close to reality). We take an approximate numerical method and after hours of coding and days of verification come up with the program or algorithm which is a solution. And if the model and an algorithm give results close to a real problem by some degree that is good enough soultion. Its worth noting the difference between exact solution algorithm and exact computation result. When considering real-world problems and real-world computation machines I believe all physical problems solutions where any calculations are taken can not be exact because universal physical constants are represented approximately in the computer. Any numbers are represented with the limited precision, at least limited by amount of memory available to computing machine. I can imagine plenty of problems where good-enough, good to some degree solution will work, like train scheduling, automated trading, satellite orbit calculation, health care expert systems. In that cases exact solutions can't be derived due to constraints on computation time, limitations in computer memory or due to the nature of problems. I googled this question and like what this guy suggests: there're kinds of mathematical problems that need exact solutions (little note here: because the question is taken from the book "Introduction to algorithms" the term "solution" means an algorithm or a program, which in this case gives exact answer on each input). But that's probably more of theoretical interest. So I would like to narrow down the question to: What are the real-world practical problems where only the best (exact) solution algorithm or program will do (but not the good-enough solution)? There are problems like breaking of cryptographic ciphers where only exact solution matters in practice and again in practice the process of deciphering without knowing a secret should take reasonable amount of time. Returning to the original question this is the problem where good-enough (fast-enough) solution will do there's no practical need in instant crack though it's desired. So the quality of "best" can be understood in any sense: exact, fastest, requiring least memory, having minimal possible network traffic etc. And still I want this question to be theoretical if possible. In a sense that there may be example of computer X that has limited resource R of amount Y where the best solution to problem P is the one that takes not more than available Y for inputs of size N*Y. But that's the problem of finding solution for P on computer X which is... well, good enough. My final thought that we live in a world where it is required from programming solutions to practical purposes to be good enough. In rare cases really very very good but still not the best ones. Isn't it? :) If it's not can you provide an example? Or can you name any such unsolved problem of practical interest?

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• What do you need to know to be a world-class master software developer? [closed]

  - by glitch

  I wanted to bring up this question to you folks and see what you think, hopefully advise me on the matter: let's say you had 30 years of learning and practicing software development in front of you, how would you dedicate your time so that you'd get the biggest bang for your buck. What would you both learn and work on to be a world-class software developer that would make a large impact on the industry and leave behind a legacy? I think that most great developers end up being both broad generalists and specialists in one-two areas of interest. I'm thinking Bill Joy, John Carmack, Linus Torvalds, K&R and so on. I'm thinking that perhaps one approach would be to break things down by categories and establish a base minimum of "software development" greatness. I'm thinking: Operating Systems: completely internalize the core concepts of OS, perhaps gain a lot of familiarity with an OSS one such as Linux. Anything from memory management to device drivers has to be complete second nature. Programming Languages: this is one of those topics that imho has to be fully grokked even if it might take many years. I don't think there's quite anything like going through the process of developing your own compiler, understanding language design trade-offs and so on. Programming Language Pragmatics is one of my favorite books actually, I think you want to have that internalized back to back, and that's just the start. You could go significantly deeper, but I think it's time well spent, because it's such a crucial building block. As a subset of that, you want to really understand the different programming paradigms out there. Imperative, declarative, logic, functional and so on. Anything from assembly to LISP should be at the very least comfortable to write in. Contexts: I believe one should have experience working in different contexts to truly be able to appreciate the trade-offs that are being made every day. Embedded, web development, mobile development, UX development, distributed, cloud computing and so on. Hardware: I'm somewhat conflicted about this one. I think you want some understanding of computer architecture at a low level, but I feel like the concepts that will truly matter will be slightly higher level, such as CPU caching / memory hierarchy, ILP, and so on. Networking: we live in a completely network-dependent era. Having a good understanding of the OSI model, knowing how the Web works, how HTTP works and so on is pretty much a pre-requisite these days. Distributed systems: once again, everything's distributed these days, it's getting progressively harder to ignore this reality. Slightly related, perhaps add solid understanding of how browsers work to that, since the world seems to be moving so much to interfacing with everything through a browser. Tools: Have a really broad toolset that you're familiar with, one that continuously expands throughout the years. Communication: I think being a great writer, effective communicator and a phenomenal team player is pretty much a prerequisite for a lot of a software developer's greatness. It can't be overstated. Software engineering: understanding the process of building software, team dynamics, the requirements of the business-side, all the pitfalls. You want to deeply understand where what you're writing fits from the market perspective. The better you understand all of this, the more of your work will actually see the daylight. This is really just a starting list, I'm confident that there's a ton of other material that you need to master. As I mentioned, you most likely end up specializing in a bunch of these areas as you go along, but I was trying to come up with a baseline. Any thoughts, suggestions and words of wisdom from the grizzled veterans out there who would like to share their thoughts and experiences with this? I'd really love to know what you think!

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• Making user input/math on data fast, unlike excel type programs

  - by proGrammar

  I'm creating a research platform solely for myself to do some research on data. Programs like excel are terribly slow for me so I'm trying to come up with another solution. Originally I used excel. A1 was the cell that contained the data and all other cells in use calculated something on A1, or on other cells, that all could be in the end traced to A1. A1 was like an element of an array, I then I incremented it to go through all my data. This was way too slow. So the only other option I found originally was to hand code in c# the calculations inside a loop. Then I simply recompiled each time I changed my math. This was terribly slow to do and I had to order everything correctly so things would update correctly (dependencies). I could have also used events, but hand coding events for each cell like calculation would also be very slow. Next I created an application to read Excel and to perfectly imitate it. Which is what I now use. Basically I write formulas onto a fraction of my data to get live results inside excel. Then my program reads excel, writes another c# program, compiles it, and runs that program which runs my excel created formulas through a lot more data a whole lot faster. The advantage being my application dependency sorts everything (or I could use events) so I don't have to (like excel does) And of course the speed. But now its not a single application anymore. Instead its 2 applications, one which only reads my formulas and writes another program. The other one being the result which only lives for a short while before I do other runs through my data with different formulas / settings. So I can't see multiple results at one time without introducing even more programs like a database or at least having the 2 applications talking to each other. My idea was to have a dll that would be written, compiled, loaded, and unloaded again and again. So a self-updating program, sort of. But apparently that's not possible without another appdomain which means data has to be marshaled to be moved between the appdomains. Which would slow things down, not for summaries, but for other stuff I need to do with all my data. I'm also forgetting to mention a huge problem with restarting an application again and again which is having to reload ALL my data into memory again and again. But its still a whole lot faster than excel. I'm really super puzzled as to what people do when they want to research data fast. I'm completely unable to have a program accept user input and having it fast. My understanding is that it would have to do things like excel which is to evaluate strings again and again. So my only option is to repeatedly compile applications. Do I have a correct understanding on computer science? I've only just began programming, and didn't think I would have to learn much to do some simple math on data. My understanding is its either compiling my user defined stuff to a program or evaluating them from a string or something stupid again and again. And my only option is to probably switch operating systems or something to be able to have a program compile and run itself without stopping (writing/compiling dll, loading dll to program, unloading, and repeating). Can someone give me some idea on how computers work? Is anything better possible? Like a running program, that can accept user input and compile it and then unload it later? I mean heck operating systems dont need to be RESTARTED with every change to user input. What is this the cave man days? Sorry, it's just so super frustrating not knowing what one can do, and can't do. If only I could understand and learn this stuff fast enough.

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• Java: immutable Stack?

  - by HH

  I chose to use Stacks and Tables before knowing Collections has immutable empty things only for Set, Map and List. Because the size of table does not change after its init: Integer[] table = new Intger[0] I can use the zero-witdh table as an empty table. But I cannot use final or empty Stack to get immutable Stack: No immutability to Stack with Final import java.io.*; import java.util.*; public class TestStack{ public static void main(String[] args) { final Stack<Integer> test = new Stack<Integer>(); Stack<Integer> test2 = new Stack<Integer>(); test.push(37707); test2.push(80437707); //WHY is there not an error to remove an elment // from FINAL stack? System.out.println(test.pop()); System.out.println(test2.pop()); } } Java Api 5 for list interface shows that Stack is an implementing class for list and arraylist, here. The java.coccurrent pkg does not have any immutable Stack data structure. From Stack to some immutable data structure How to get immutable Stack data structure? Can I box it with list? Should I switch my current implementatios from stacks to Lists to get immutable? Which immutable data structure is Very fast with about similar exec time as Stack?

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• "The calling thread cannot access this object because a different thread owns it." While using Dispa

  - by Sdry

  I have an application, that I want to load additional xaml files, being resourcedictionaries controling the style of the application. Yet when trying to add a loaded ResourceDictionary to the mergeddictionaries I get an InvalidOperationException saying "The calling thread cannot access this object because a different thread owns it." at a point where I am not even using multiple threads. The application contains a usercontrol which loads the xaml file through a background worker, adding the loaded ResourceDictionaries to an Observablecollection. When I pass on a selected theme(=ResourceDictionary) to a function in the mainwindow of the application, it goes wrong. public void LoadTheme(Theme theme) {//sdry 2010-4-22 if(theme !=null){ this._dispatcher.Invoke(DispatcherPriority.Normal, (Action)(() => { MessageBox.Show("SKIN TEST: " + theme.Name); //> oke #if (SHOWDEBUGINFO) _selectedTheme = theme.Name; //>oke #endif Application.Current.Resources.MergedDictionaries.Clear(); //>oke Application.Current.Resources.MergedDictionaries.Add(theme.ResourceDictionary); //> InvalidOperationException //the theme object has a property named ResourceDictionary of type ResourceDictionary containing the loaded xaml })); } } My first reaction was to use the Disatcher.Invoke, even not knowing how I would not be on the gui thread, which doesn't solve a thing. So maybe my loaded theme belongs to a different thread ? but its originating from a property of a usercontrol, which should be the same thread. And its accesable untill trying to use the ResourceDictionary. This makes me confused, and not very aware of how to proceed, any help is appreciated.

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