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• Updated Agenda for OTN Architect Day Los Angeles (Oct 25)

  - by Bob Rhubart

  Here's the latest information on the session schedule and content for Oracle Technology Network Architect Day in Los Angeles on October 25, 2012. Registration is open, but seating is limited. When: Thursday October 25 12, 2012 8:30am – 5:00pm Where: Sofitel Los Angeles 8555 Beverly Boulevard Los Angeles, CA 90048 Agenda Time Session Title Room 8:30 am - 9:00 am Registration and Continental Breakfast 9:00 am - 9:15 am Welcome and Opening Comments | Bob Rhubart Beverly Ballroom 9:15 am - 10:00 am Engineered Systems: Oracle's Vision for the Future | Ralf Dossmann Oracle's Exadata and Exalogic are impressive products in their own right. But working in combination they deliver unparalleled transaction processing performance with up to a 30x increase over existing legacy systems, with the lowest cost of ownership over a 3 or 5 year basis than any other hardware. In this session you'll learn how to leverage Oracle's Engineered Systems within your enterprise to deliver record-breaking performance at the lowest TCO. Beverly Ballroom 10:00 am - 10:30 am Monitoring and Managing Applications in the Cloud | Basheer Khan Oracle offers a broad portfolio of software and hardware products and services to enable public, private and hybrid clouds to power the enterprise. However, enterprise cloud computing presents new management challenges, that need to be addressed to realize the economic benefits of cloud computing. In this session you will learn about the methods and tools you can use to proactively monitor your end-to-end Oracle Applications environment in the cloud, define service-level objectives, gain insight into your end users, and troubleshoot performance problems from a single console. Beverly Ballroom 10:30 am - 10:45 am Break 10:45 am - 11:30 am Breakout Sessions (pick one) Cloud Computing - Making IT Simple | Dr. James Baty The road to Cloud Computing is not without a few bumps. This session will help to smooth out your journey by tackling some of the potential complications. We'll examine whether standardization is a prerequisite for the Cloud. We'll look at why refactoring isn't just for application code. We'll check out deployable entities and their simplification via higher levels of abstraction. And we'll close out the session with a look at engineered systems and modular clouds. Beverly Ballroom Innovations in Grid Computing with Oracle Coherence | Ashok Aletty Learn how Oracle Coherence can increase the availability, scalability and performance of your existing applications with its advanced low-latency data-grid technologies. Also hear some interesting industry-specific use cases that customers had implemented and how Oracle is integrating Coherence into its Enterprise Java stack. Hollywood Room 11:30 am - 12:15 pm Breakout Sessions (pick one) Enterprise Strategy for Cloud Security | Dave Chappelle Security is high on the list of concerns for many organizations as they evaluate their cloud computing options. This session will examine security in the context of the various forms of cloud computing. We'll consider technical and non-technical aspects of security, and discuss several strategies for cloud computing, from both the consumer and producer perspectives. Beverly Ballroom Oracle Enterprise Manager | Perren Walker This session examines new Oracle Enterprise Manager monitoring, administration, and management features for Oracle Exalogic. It focuses on two management themes: cloud management related to virtualization and applications-to-disk management. For private cloud management, it discusses virtualization management features providing an enhanced set of application deployment capabilities enabling IaaS as well as PaaS interactions. Then from an end-to-end perspective, it covers the specific capabilities and—where applicable—best practices for machine, cloud, middleware, and application administration. Hollywood Room 12:15 pm - 1:15 pm Lunch Beverly Ballroom Lounge 1:15 pm - 2:00 pm Panel Discussion - Q&A with session speakers Beverly Ballroom 2:00 pm - 2:45 pm Breakout Sessions (pick one) Oracle Cloud Reference Architecture | Anbu Krishnaswamy Cloud initiatives are beginning to dominate enterprise IT roadmaps. Successful adoption of Cloud and the subsequent governance challenges warrant a Cloud reference architecture that is applied consistently across the enterprise. This presentation will answer the important questions: What exactly is a Cloud, why you need it, what changes it will bring to the enterprise, and what are the key capabilities of a Cloud infrastructure are - using Oracle's Cloud Reference Architecture, which is part of the IT Strategies from Oracle (ITSO) Cloud Enterprise Technology Strategy ETS). Beverly Ballroom 21st Century SOA | Jeff Davies Service Oriented Architecture has evolved from concept to reality in the last decade. The right methodology coupled with mature SOA technologies has helped customers demonstrate success in both innovation and ROI. In this session you will learn how Oracle SOA Suite's orchestration, virtualization, and governance capabilities provide the infrastructure to run mission critical business and system applications. We'll also take a special look at the convergence of SOA & BPM using Oracle's Unified technology stack. Hollywood Room 2:45 pm - 3:00 pm Break 3:00 pm - 4:00 pm Roundtable Discussion Beverly Ballroom 4:00 pm - 4:15 pm Closing Comments & Readouts from Roundtables Beverly Ballroom 4:15 pm - 5:00 pm Networking / Reception Beverly Ballroom Lounge Note: Session schedule and content subject to change.

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• Agile Executives

  - by Robert May

  Over the years, I have experienced many different styles of software development. In the early days, most of the development was Waterfall development. In the last few years, I’ve become an advocate of Scrum. As I talked about last month, many people have misconceptions about what Scrum really is. The reason why we do Scrum at Veracity is because of the difference it makes in the life of the team doing Scrum. Software is for people, and happy motivated people will build better software. However, not all executives understand Scrum and how to get the information from development teams that use Scrum. I think that these executives need a support system for managing Agile teams. Historical Software Management When Henry Ford pioneered the assembly line, I doubt he realized the impact he’d have on Management through the ages. Historically, management was about managing the process of building things. The people were just cogs in that process. Like all cogs, they were replaceable. Unfortunately, most of the software industry followed this same style of management. Many of today’s senior managers learned how to manage companies before software was a significant influence on how the company did business. Software development is a very creative process, but too many managers have treated it like an assembly line. Idea’s go in, working software comes out, and we just have to figure out how to make sure that the ideas going in are perfect, then the software will be perfect. Lean Manufacturing In the manufacturing industry, Lean manufacturing has revolutionized Henry Ford’s assembly line. Derived from the Toyota process, Lean places emphasis on always providing value for the customer. Anything the customer wouldn’t be willing to pay for is wasteful. Agile is based on similar principles. We’re building software for people, and anything that isn’t useful to them doesn’t add value. Waterfall development would have teams build reams and reams of documentation about how the software should work. Agile development dispenses with this work because excessive documentation doesn’t add value. Instead, teams focus on building documentation only when it truly adds value to the customer. Many other Agile principals are similar. Playing Catch-up Just like in the manufacturing industry, many managers in the software industry have yet to understand the value of the principles of Lean and Agile. They think they can wrap the uncertainties of software development up in a nice little package and then just execute, usually followed by failure. They spend a great deal of time and money trying to exactly predict the future. That expenditure of time and money doesn’t add value to the customer. Managers that understand that Agile know that there is a better way. They will instead focus on the priorities of the near term in detail, and leave the future to take care of itself. They have very detailed two week plans with less detailed quarterly plans. These plans are guided by a general corporate strategy that doesn’t focus on the exact implementation details. These managers also think in smaller features rather than large functionality. This adds a great deal of value to customers, since the features that matter most are the ones that the team focuses on in the near term and then are able to deliver to the customers that are paying for them. Agile managers also realize that stale software is very costly. They know that keeping the technology in their software current is much less expensive and risky than large rewrites that occur infrequently and schedule time in each release for refactoring of the existing software. Agile Executives Even though Agile is a better way, I’ve still seen failures using the Agile process. While some of these failures can be attributed to the team, most of them are caused by managers, not the team. Managers fail to understand what Agile is, how it works, and how to get the information that they need to make good business decisions. I think this is a shame. I’m very pleased that Veracity understands this problem and is trying to do something about it. Veracity is a key sponsor of Agile Executives. In fact, Galen is this year’s acting president for Agile Executives. The purpose of Agile Executives is to help managers better manage Agile teams and see better success. Agile Executives is trying to build a community of executives that range from managers interested in Agile to managers that have successfully adopted Agile. Together, these managers can form a community of support and ideas that will help make Agile teams more successful. Helping Your Team You can help too! Talk with your manager and get them involved in Agile Executives. Help Veracity build the community. If your manager understands Agile better, he’ll understand how to help his teams, which will result in software that adds more value for customers. If you have any questions about how you can be involved, please let me know. Technorati Tags: Agile,Agile Executives

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• When is my View too smart?

  - by Kyle Burns

  In this posting, I will discuss the motivation behind keeping View code as thin as possible when using patterns such as MVC, MVVM, and MVP.  Once the motivation is identified, I will examine some ways to determine whether a View contains logic that belongs in another part of the application.  While the concepts that I will discuss are applicable to most any pattern which favors a thin View, any concrete examples that I present will center on ASP.NET MVC. Design patterns that include a Model, a View, and other components such as a Controller, ViewModel, or Presenter are not new to application development.  These patterns have, in fact, been around since the early days of building applications with graphical interfaces.  The reason that these patterns emerged is simple – the code running closest to the user tends to be littered with logic and library calls that center around implementation details of showing and manipulating user interface widgets and when this type of code is interspersed with application domain logic it becomes difficult to understand and much more difficult to adequately test.  By removing domain logic from the View, we ensure that the View has a single responsibility of drawing the screen which, in turn, makes our application easier to understand and maintain. I was recently asked to take a look at an ASP.NET MVC View because the developer reviewing it thought that it possibly had too much going on in the view.  I looked at the .CSHTML file and the first thing that occurred to me was that it began with 40 lines of code declaring member variables and performing the necessary calculations to populate these variables, which were later either output directly to the page or used to control some conditional rendering action (such as adding a class name to an HTML element or not rendering another element at all).  This exhibited both of what I consider the primary heuristics (or code smells) indicating that the View is too smart: Member variables – in general, variables in View code are an indication that the Model to which the View is being bound is not sufficient for the needs of the View and that the View has had to augment that Model.  Notable exceptions to this guideline include variables used to hold information specifically related to rendering (such as a dynamically determined CSS class name or the depth within a recursive structure for indentation purposes) and variables which are used to facilitate looping through collections while binding. Arithmetic – as with member variables, the presence of arithmetic operators within View code are an indication that the Model servicing the View is insufficient for its needs.  For example, if the Model represents a line item in a sales order, it might seem perfectly natural to “normalize” the Model by storing the quantity and unit price in the Model and multiply these within the View to show the line total.  While this does seem natural, it introduces a business rule to the View code and makes it impossible to test that the rounding of the result meets the requirement of the business without executing the View.  Within View code, arithmetic should only be used for activities such as incrementing loop counters and calculating element widths. In addition to the two characteristics of a “Smart View” that I’ve discussed already, this View also exhibited another heuristic that commonly indicates to me the need to refactor a View and make it a bit less smart.  That characteristic is the existence of Boolean logic that either does not work directly with properties of the Model or works with too many properties of the Model.  Consider the following code and consider how logic that does not work directly with properties of the Model is just another form of the “member variable” heuristic covered earlier: @if(DateTime.Now.Hour < 12) {     <div>Good Morning!</div> } else {     <div>Greetings</div> } This code performs business logic to determine whether it is morning.  A possible refactoring would be to add an IsMorning property to the Model, but in this particular case there is enough similarity between the branches that the entire branching structure could be collapsed by adding a Greeting property to the Model and using it similarly to the following: <div>@Model.Greeting</div> Now let’s look at some complex logic around multiple Model properties: @if (ModelPageNumber + Model.NumbersToDisplay == Model.PageCount         || (Model.PageCount != Model.CurrentPage             && !Model.DisplayValues.Contains(Model.PageCount))) {     <div>There's more to see!</div> } In this scenario, not only is the View code difficult to read (you shouldn’t have to play “human compiler” to determine the purpose of the code), but it also complex enough to be at risk for logical errors that cannot be detected without executing the View.  Conditional logic that requires more than a single logical operator should be looked at more closely to determine whether the condition should be evaluated elsewhere and exposed as a single property of the Model.  Moving the logic above outside of the View and exposing a new Model property would simplify the View code to: @if(Model.HasMoreToSee) {     <div>There’s more to see!</div> } In this posting I have briefly discussed some of the more prominent heuristics that indicate a need to push code from the View into other pieces of the application.  You should now be able to recognize these symptoms when building or maintaining Views (or the Models that support them) in your applications.

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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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• Dealing with "I-am-cool-and-you-are-dumb" manager [closed]

  - by Software Guy

  I have been working with a software company for about 6 months now. I like the projects I work on there and I really like all the people there except for 1 guy. That guy is technically smart, and he is a co-founder of the company. He is an okay guy in person (the kind you wouldn't want to care about much) but things get tricky when he is your manager. In general I am all okay but there are times when I feel I am not being treated fairly: He doesn't give much thought to when he makes mistakes and when I do something similar, he is super critical. Recently he went as far as to say "I am not sure if I can trust you with this feature". The detais of this specific case are this: I was working on this feature, and I was already a couple of hours over my normal working hours, and then I decided to stop and continue tomorrow. We use git, and I like to commit changes locally and only push when I feel they are ready. This manager insists that I push all the changes to the central repo (in case my hard drive crashes). So I push the change, and the ticket is marked as "to be tested". Next day I come in, he sits next to me and starts complaining and says that I posted above. I really didn't know what to say, I tried to explain to him that the ticket is still being worked upon but he didn't seem to listen. He interrupts me in-between when I am coding, which I do not mind, but when I do that same, his face turns like this :| and reacts as if his work was super important and I am just wasting his time. He asks me to accumulate all questions, and then ask him altogether which is not always possible, as you need a clarification before you can continue on a feature implementation. And when I am coding, he talks on the phone with his customers next to me (when he can go to the meeting room with his laptop) and doesn't care. He made me switch to a whole new IDE (from Netbeans to a commercial IDE costing a lot of money) for a really tiny feature (which I later found out was in Netbeans as well!). I didn't make a big deal out of it as I am equally comfortable working with this new IDE, but I couldn't get the science behind his obsession. He said this feature makes sure that if any method is updated by a programmer, the IDE will turn the method name to red in places where it is used. I told him that I do not have a problem since I always search for method usage in the project and make sure its updated. IDEs even have refactoring features for exactly that, but... I recently implemented a feature for a project, and I was happy about it and considering him a senior, I asked him his comments about the implementation quality.. he thought long and hard, made a few funny faces, and when he couldn't find anything, he said "ummm, your program will crash if JS is disabled" - he was wrong, since I had made sure it would work fine with default values even if JS was disabled. I told him that and then he said "oh okay". BUT, the funny thing is, a few days back, he implemented something and I objected with "But that would not run if JS is disabled" and his response was "We don't have to care about people who disable JS" :-/ Once he asked me to investigate if there was a way to modify a CMS generated menu programmatically by extending the CMS, I did my research and told him that the only was is to inject a menu item using JavaScript / jQuery and his reaction was "ah that's ugly, and hacky, not acceptable" and two days later, I see that feature implemented in the same way as I had suggested. The point is, his reaction was not respectful at all, even if what I proposed was hacky, he should be respectful, that I know what's hacky and if I am suggesting something hacky, there must be a reason for it. There are plenty of other reasons / examples where I feel I am not being treated fairly. I want your advice as to what is it that I am doing wrong and how to deal with such a situation. The other guys in the team are actually very good people, and I do not want to leave the job either (although I could, if I want to). All I want is respect and equal treatment. I have thought about talking to this guy in a face to face meeting, but that worries me that his attitude might get worse and make things more difficult for me (since he doesn't seem to be the guy who thinks he can be wrong too). I am also considering talking to the other co-founder but I am not sure how he will take it (as both founders have been friends forever). Thanks for reading the long message, I really appreciate your help.

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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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• Null Values And The T-SQL IN Operator

  - by Jesse

  I came across some unexpected behavior while troubleshooting a failing test the other day that took me long enough to figure out that I thought it was worth sharing here. I finally traced the failing test back to a SELECT statement in a stored procedure that was using the IN t-sql operator to exclude a certain set of values. Here’s a very simple example table to illustrate the issue: Customers CustomerId INT, NOT NULL, Primary Key CustomerName nvarchar(100) NOT NULL SalesRegionId INT NULL   The ‘SalesRegionId’ column contains a number representing the sales region that the customer belongs to. This column is nullable because new customers get created all the time but assigning them to sales regions is a process that is handled by a regional manager on a periodic basis. For the purposes of this example, the Customers table currently has the following rows: CustomerId CustomerName SalesRegionId 1 Customer A 1 2 Customer B NULL 3 Customer C 4 4 Customer D 2 5 Customer E 3   How could we write a query against this table for all customers that are NOT in sales regions 2 or 4? You might try something like this: 1: SELECT 2: CustomerId, 3: CustomerName, 4: SalesRegionId 5: FROM Customers 6: WHERE SalesRegionId NOT IN (2,4)   Will this work? In short, no; at least not in the way that you might expect. Here’s what this query will return given the example data we’re working with: CustomerId CustomerName SalesRegionId 1 Customer A 1 5 Customer E 5   I was expecting that this query would also return ‘Customer B’, since that customer has a NULL SalesRegionId. In my mind, having a customer with no sales region should be included in a set of customers that are not in sales regions 2 or 4.When I first started troubleshooting my issue I made note of the fact that this query should probably be re-written without the NOT IN clause, but I didn’t suspect that the NOT IN clause was actually the source of the issue. This particular query was only one minor piece in a much larger process that was being exercised via an automated integration test and I simply made a poor assumption that the NOT IN would work the way that I thought it should. So why doesn’t this work the way that I thought it should? From the MSDN documentation on the t-sql IN operator: If the value of test_expression is equal to any value returned by subquery or is equal to any expression from the comma-separated list, the result value is TRUE; otherwise, the result value is FALSE. Using NOT IN negates the subquery value or expression. The key phrase out of that quote is, “… is equal to any expression from the comma-separated list…”. The NULL SalesRegionId isn’t included in the NOT IN because of how NULL values are handled in equality comparisons. From the MSDN documentation on ANSI_NULLS: The SQL-92 standard requires that an equals (=) or not equal to (<>) comparison against a null value evaluates to FALSE. When SET ANSI_NULLS is ON, a SELECT statement using WHERE column_name = NULL returns zero rows even if there are null values in column_name. A SELECT statement using WHERE column_name <> NULL returns zero rows even if there are nonnull values in column_name. In fact, the MSDN documentation on the IN operator includes the following blurb about using NULL values in IN sub-queries or expressions that are used with the IN operator: Any null values returned by subquery or expression that are compared to test_expression using IN or NOT IN return UNKNOWN. Using null values in together with IN or NOT IN can produce unexpected results. If I were to include a ‘SET ANSI_NULLS OFF’ command right above my SELECT statement I would get ‘Customer B’ returned in the results, but that’s definitely not the right way to deal with this. We could re-write the query to explicitly include the NULL value in the WHERE clause: 1: SELECT 2: CustomerId, 3: CustomerName, 4: SalesRegionId 5: FROM Customers 6: WHERE (SalesRegionId NOT IN (2,4) OR SalesRegionId IS NULL)   This query works and properly includes ‘Customer B’ in the results, but I ultimately opted to re-write the query using a LEFT OUTER JOIN against a table variable containing all of the values that I wanted to exclude because, in my case, there could potentially be several hundred values to be excluded. If we were to apply the same refactoring to our simple sales region example we’d end up with: 1: DECLARE @regionsToIgnore TABLE (IgnoredRegionId INT) 2: INSERT @regionsToIgnore values (2),(4) 3:  4: SELECT 5: c.CustomerId, 6: c.CustomerName, 7: c.SalesRegionId 8: FROM Customers c 9: LEFT OUTER JOIN @regionsToIgnore r ON r.IgnoredRegionId = c.SalesRegionId 10: WHERE r.IgnoredRegionId IS NULL By performing a LEFT OUTER JOIN from Customers to the @regionsToIgnore table variable we can simply exclude any rows where the IgnoredRegionId is null, as those represent customers that DO NOT appear in the ignored regions list. This approach will likely perform better if the number of sales regions to ignore gets very large and it also will correctly include any customers that do not yet have a sales region.

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• Avoiding coupling

  - by Seralize

  It is also true that a system may become so coupled, where each class is dependent on other classes that depend on other classes, that it is no longer possible to make a change in one place without having a ripple effect and having to make subsequent changes in many places.[1] This is why using an interface or an abstract class can be valuable in any object-oriented software project. Quote from Wikipedia Starting from scratch I'm starting from scratch with a project that I recently finished because I found the code to be too tightly coupled and hard to refactor, even when using MVC. I will be using MVC on my new project aswell but want to try and avoid the pitfalls this time, hopefully with your help. Project summary My issue is that I really wish to keep the Controller as clean as possible, but it seems like I can't do this. The basic idea of the program is that the user picks wordlists which is sent to the game engine. It will pick random words from the lists until there are none left. Problem at hand My main problem is that the game will have 'modes', and need to check the input in different ways through a method called checkWord(), but exactly where to put this and how to abstract it properly is a challenge to me. I'm new to design patterns, so not sure whether there exist any might fit my problem. My own attempt at abstraction Here is what I've gotten so far after hours of 'refactoring' the design plans, and I know it's long, but it's the best I could do to try and give you an overview (Note: As this is the sketch, anything is subject to change, all help and advice is very welcome. Also note the marked coupling points): Wordlist class Wordlist { // Basic CRUD etc. here! // Other sample methods: public function wordlistCount($user_id) {} // Returns count of how many wordlists a user has public function getAll($user_id) {} // Returns all wordlists of a user } Word class Word { // Basic CRUD etc. here! // Other sample methods: public function wordCount($wordlist_id) {} // Returns count of words in a wordlist public function getAll($wordlist_id) {} // Returns all words from a wordlist public function getWordInfo($word_id) {} // Returns information about a word } Wordpicker class Wordpicker { // The class needs to know which words and wordlists to exclude protected $_used_words = array(); protected $_used_wordlists = array(); // Wordlists to pick words from protected $_wordlists = array(); /* Public Methods */ public function setWordlists($wordlists = array()) {} public function setUsedWords($used_words = array()) {} public function setUsedWordlists($used_wordlists = array()) {} public function getRandomWord() {} // COUPLING POINT! Will most likely need to communicate with both the Wordlist and Word classes /* Protected Methods */ protected function _checkAvailableWordlists() {} // COUPLING POINT! Might need to check if wordlists are deleted etc. protected function _checkAvailableWords() {} // COUPLING POINT! Method needs to get all words in a wordlist from the Word class } Game class Game { protected $_session_id; // The ID of a game session which gets stored in the database along with game details protected $_game_info = array(); // Game instantiation public function __construct($user_id) { if (! $this->_session_id = $this->_gameExists($user_id)) { // New game } else { // Resume game } } // This is the method I tried to make flexible by using abstract classes etc. // Does it even belong in this class at all? public function checkWord($answer, $native_word, $translation) {} // This method checks the answer against the native word / translation word, depending on game mode public function getGameInfo() {} // Returns information about a game session, or creates it if it does not exist public function deleteSession($session_id) {} // Deletes a game session from the database // Methods dealing with game session information protected function _gameExists($user_id) {} protected function _getProgress($session_id) {} protected function _updateProgress($game_info = array()) {} } The Game /* CONTROLLER */ /* "Guess the word" page */ // User input $game_type = $_POST['game_type']; // Chosen with radio buttons etc. $wordlists = $_POST['wordlists']; // Chosen with checkboxes etc. // Starts a new game or resumes one from the database $game = new Game($_SESSION['user_id']); $game_info = $game->getGameInfo(); // Instantiates a new Wordpicker $wordpicker = new Wordpicker(); $wordpicker->setWordlists((isset($game_info['wordlists'])) ? $game_info['wordlists'] : $wordlists); $wordpicker->setUsedWordlists((isset($game_info['used_wordlists'])) ? $game_info['used_wordlists'] : NULL); $wordpicker->setUsedWords((isset($game_info['used_words'])) ? $game_info['used_words'] : NULL); // Fetches an available word if (! $word_id = $wordpicker->getRandomWord()) { // No more words left - game over! $game->deleteSession($game_info['id']); redirect(); } else { // Presents word details to the user $word = new Word(); $word_info = $word->getWordInfo($word_id); } The Bit to Finish /* CONTROLLER */ /* "Check the answer" page */ // ?????????????????? ( http://pastebin.com/cc6MtLTR ) Make sure you toggle the 'Layout Width' to the right for a better view. Thanks in advance. Questions To which extent should objects be loosely coupled? If object A needs info from object B, how is it supposed to get this without losing too much cohesion? As suggested in the comments, models should hold all business logic. However, as objects should be independent, where to glue them together? Should the model contain some sort of "index" or "client" area which connects the dots? Edit: So basically what I should do for a start is to make a new model which I can more easily call with oneliners such as $model->doAction(); // Lots of code in here which uses classes! How about the method for checking words? Should it be it's own object? I'm not sure where I should put it as it's pretty much part of the 'game'. But on another hand, I could just leave out the 'abstraction and OOPness' and make it a method of the 'client model' which will be encapsulated from the controller anyway. Very unsure about this.

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• Plagued by multithreaded bugs

  - by koncurrency

  On my new team that I manage, the majority of our code is platform, TCP socket, and http networking code. All C++. Most of it originated from other developers that have left the team. The current developers on the team are very smart, but mostly junior in terms of experience. Our biggest problem: multi-threaded concurrency bugs. Most of our class libraries are written to be asynchronous by use of some thread pool classes. Methods on the class libraries often enqueue long running taks onto the thread pool from one thread and then the callback methods of that class get invoked on a different thread. As a result, we have a lot of edge case bugs involving incorrect threading assumptions. This results in subtle bugs that go beyond just having critical sections and locks to guard against concurrency issues. What makes these problems even harder is that the attempts to fix are often incorrect. Some mistakes I've observed the team attempting (or within the legacy code itself) includes something like the following: Common mistake #1 - Fixing concurrency issue by just put a lock around the shared data, but forgetting about what happens when methods don't get called in an expected order. Here's a very simple example: void Foo::OnHttpRequestComplete(statuscode status) { m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } So now we have a bug in which Shutdown could get called while OnHttpNetworkRequestComplete is occuring on. A tester finds the bug, captures the crash dump, and assigns the bug to a developer. He in turn fixes the bug like this. void Foo::OnHttpRequestComplete(statuscode status) { AutoLock lock(m_cs); m_pBar->DoSomethingImportant(status); } void Foo::Shutdown() { AutoLock lock(m_cs); m_pBar->Cleanup(); delete m_pBar; m_pBar=nullptr; } The above fix looks good until you realize there's an even more subtle edge case. What happens if Shutdown gets called before OnHttpRequestComplete gets called back? The real world examples my team has are even more complex, and the edge cases are even harder to spot during the code review process. Common Mistake #2 - fixing deadlock issues by blindly exiting the lock, wait for the other thread to finish, then re-enter the lock - but without handling the case that the object just got updated by the other thread! Common Mistake #3 - Even though the objects are reference counted, the shutdown sequence "releases" it's pointer. But forgets to wait for the thread that is still running to release it's instance. As such, components are shutdown cleanly, then spurious or late callbacks are invoked on an object in an state not expecting any more calls. There are other edge cases, but the bottom line is this: Multithreaded programming is just plain hard, even for smart people. As I catch these mistakes, I spend time discussing the errors with each developer on developing a more appropriate fix. But I suspect they are often confused on how to solve each issue because of the enormous amount of legacy code that the "right" fix will involve touching. We're going to be shipping soon, and I'm sure the patches we're applying will hold for the upcoming release. Afterwards, we're going to have some time to improve the code base and refactor where needed. We won't have time to just re-write everything. And the majority of the code isn't all that bad. But I'm looking to refactor code such that threading issues can be avoided altogether. One approach I am considering is this. For each significant platform feature, have a dedicated single thread where all events and network callbacks get marshalled onto. Similar to COM apartment threading in Windows with use of a message loop. Long blocking operations could still get dispatched to a work pool thread, but the completion callback is invoked on on the component's thread. Components could possibly even share the same thread. Then all the class libraries running inside the thread can be written under the assumption of a single threaded world. Before I go down that path, I am also very interested if there are other standard techniques or design patterns for dealing with multithreaded issues. And I have to emphasize - something beyond a book that describes the basics of mutexes and semaphores. What do you think? I am also interested in any other approaches to take towards a refactoring process. Including any of the following: Literature or papers on design patterns around threads. Something beyond an introduction to mutexes and semaphores. We don't need massive parallelism either, just ways to design an object model so as to handle asynchronous events from other threads correctly. Ways to diagram the threading of various components, so that it will be easy to study and evolve solutions for. (That is, a UML equivalent for discussing threads across objects and classes) Educating your development team on the issues with multithreaded code. What would you do?

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• MVC2 Client validation with Annotations in View with RenderAction

  - by Olle

  I'm having problem with client side validation on a View that renders a dropdownlist with help of a Html.RenderAction. I have two controllers. SpecieController and CatchController and I've created ViewModels for my views. I want to keep it as DRY as possible and I will most probably need a DropDownList for all Specie elsewhere in the near future. When I create a Catch i need to set a relationship to one specie, I do this with an id that I get from the DropDownList of Species. ViewModels.Catch.Create [Required] public int Length { get; set; } [Required] public int Weight { get; set; } [Required] [Range(1, int.MaxValue)] public int SpecieId { get; set; } ViewModels.Specie.List public DropDownList(IEnumerable<SelectListItem> species) { this.Species = species; } public IEnumerable<SelectListItem> Species { get; private set; } My View for the Catch.Create action uses the ViewModels.Catch.Create as a model. But it feels that I'm missing something in the implemetation. What I want in my head is to connect the selected value in the DropDownList that comes from the RenderAction to my SpecieId. View.Catch.Create <div class="editor-label"> <%: Html.LabelFor(model => model.SpecieId) %> </div> <div class="editor-field"> <%-- Before DRY refactoring, works like I want but not DRY <%: Html.DropDownListFor(model => model.SpecieId, Model.Species) %> --%> <% Html.RenderAction("DropDownList", "Specie"); %> <%: Html.ValidationMessageFor(model => model.SpecieId) %> </div> CatchController.Create [HttpPost] public ActionResult Create(ViewModels.CatchModels.Create myCatch) { if (ModelState.IsValid) { // Can we make this StronglyTyped? int specieId = int.Parse(Request["Species"]); // Save to db Catch newCatch = new Catch(); newCatch.Length = myCatch.Length; newCatch.Weight = myCatch.Weight; newCatch.Specie = SpecieService.GetById(specieId); newCatch.User = UserService.GetUserByUsername(User.Identity.Name); CatchService.Save(newCatch); } This scenario works but not as smooth as i want. ClientSide validation does not work for SpecieId (after i refactored), I see why but don't know how I can ix it. Can I "glue" the DropDownList SelectedValue into myCatch so I don't need to get the value from Request["Species"] Thanks in advance for taking your time on this.

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• WPF Converter and NotifyOnTargetUpdated exclusive in a binding ?

  - by Mathieu Garstecki

  Hi, I have a problem with a databinding in WPF. When I try to use a value converter and set the NotifyOnTargetUpdated=True property to True, I get an XamlParseException with the following message: 'System.Windows.Data.BindingExpression' value cannot be assigned to property 'Contenu' of object 'View.UserControls.ShadowedText'. Value cannot be null. Parameter name: textToFormat Error at object 'System.Windows.Data.Binding' in markup file 'View.UserControls;component/saletotal.xaml' Line 363 Position 95. The binding is pretty standard: <my:ShadowedText Contenu="{Binding Path=Total, Converter={StaticResource CurrencyToStringConverter}, NotifyOnTargetUpdated=True}" TargetUpdated="MontantTotal_TargetUpdated"> </my:ShadowedText> (Styling properties removed for conciseness) The converter exists in the resources and works correctly when NotifyOnTargetUpdated=True is removed. Similarly, the TargetUpdated event is called and implemented correctly, and works when the converter is removed. Note: This binding is defined in a ControlTemplate, though I don't think that is relevant to the problem. Can anybody explain me what is happening ? Am I defining the binding wrong ? Are those features mutually exclusive (and in this case, can you explain why it is so) ? Thanks in advance. More info: Here is the content of the TargetUpdated handler: private void MontantTotal_TargetUpdated(object sender, DataTransferEventArgs e) { ShadowedText textBlock = (ShadowedText)e.TargetObject; double textSize = textBlock.Taille; double delta = 5; double defaultTaille = 56; double maxWidth = textBlock.MaxWidth; while (true) { FormattedText newFormat = new FormattedText(textBlock.Contenu, CultureInfo.CurrentCulture, FlowDirection.LeftToRight, new Typeface("Calibri"), textSize, (SolidColorBrush) Resources["RougeVif"]); if (newFormat.Width < textBlock.MaxWidth && textSize <= defaultTaille) { if ((Math.Round(newFormat.Width) + delta) >= maxWidth || textSize == defaultTaille) { break; } textSize++; } else { if ((Math.Round(newFormat.Width) - delta) <= maxWidth && textSize <= defaultTaille) { break; } textSize--; } } textBlock.Taille = textSize; } The role of the handler is to resize the control based on the length of the content. It is quite ugly but I want to have the functional part working before refactoring.

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• Does my fat-client application belong in the MVC pattern?

  - by boatingcow

  The web-based application I’m currently working on is growing arms and legs! It’s basically an administration system which helps users to keep track of bookings, user accounts, invoicing etc. It can also be accessed via a couple of different websites using a fairly crude API. The fat-client design loosely follows the MVC pattern (or perhaps MVP) with a php/MySQL backend, Front Controller, several dissimilar Page Controllers, a liberal smattering of object-oriented and procedural Models, a confusing bunch of Views and templates, some JavaScripts, CSS files and Flash objects. The programmer in me is a big fan of the principle of “Separation of Concerns” and on that note, I’m currently trying to figure out the best way to separate and combine the various concerns as the project grows and more people contribute to it. The problem we’re facing is that although JavaScript (or Flash with ActionScript) is normally written with the template, hence part of the View and decoupled from the Controller and Model, we find that it actually encompasses the entire MVC pattern... Swap an image with an onmouseover event - that’s Behaviour. Render a datagrid - we’re manipulating the View. Send the result of reordering a list via AJAX - now we’re in Control. Check a form field to see if an email address is in a valid format - we’re consulting the Model. Is it wise to let the database people write up the validation Model with jQuery? Can the php programmers write the necessary Control structures in JavaScript? Can the web designers really write a functional AJAX form for their View? Should there be a JavaScript overlord for every project? If the MVC pattern could be applied to the people instead of the code, we would end up with this: Model - the database boffins - “SELECT * FROM mind WHERE interested IS NULL” Control - pesky programmers - “class Something extends NothingAbstractClass{…}” View - traditionally the domain of the graphic/web designer - “” …and a new layer: Behaviour - interaction and feedback designer - “CSS3 is the new black…” So, we’re refactoring and I’d like to stick to best practice design, but I’m not sure how to proceed. I don’t want to reinvent the wheel, so would anyone have any hints or tips as to what pattern I should be looking at or any code samples from someone who’s already done the dirty work? As the programmer guy, how can I rewrite the app for backend and front end whilst keeping the two separate? And before you ask, yes I’ve looked at Zend, CodeIgnitor, Symfony, etc., and no, they don’t seem to cross the boundary between server logic and client logic!

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• What's the best way to structure this Linq-to-Events Drag & Drop code?

  - by Rob Fonseca-Ensor

  I am trying to handle a drag & drop interaction, which involves mouse down, mouse move, and mouse up. Here is a simplified repro of my solution that: on mouse down, creates an ellipse and adds it to a canvas on mouse move, repositions the ellipse to follow the mouse on mouse up, changes the colour of the canvas so that it's obvious which one you're dragging. var mouseDown = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonDown"); var mouseUp = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonUp"); var mouseMove = Observable.FromEvent<MouseEventArgs>(canvas, "MouseMove"); Ellipse ellipse = null; var q = from start in mouseDown.Do(x => { // handle mousedown by creating a red ellipse, // adding it to the canvas at the right position ellipse = new Ellipse() { Width = 10, Height = 10, Fill = Brushes.Red }; Point position = x.EventArgs.GetPosition(canvas); Canvas.SetLeft(ellipse, position.X); Canvas.SetTop(ellipse, position.Y); canvas.Children.Add(ellipse); }) from delta in mouseMove.Until(mouseUp.Do(x => { // handle mouse up by making the ellipse green ellipse.Fill = Brushes.Green; })) select delta; q.Subscribe(x => { // handle mouse move by repositioning ellipse Point position = x.EventArgs.GetPosition(canvas); Canvas.SetLeft(ellipse, position.X); Canvas.SetTop(ellipse, position.Y); }); the XAML is simply <Canvas x:Name="canvas"/> There's a few things I don't like about this code, and I need help refactoring it :) First of all: the mousedown and mouseup callbacks are specified as side effects. If two subscriptions are made to q, they will happen twice. Second, the mouseup callback is specified before the mousemove callback. This makes it a bit hard to read. Thirdly, the reference to the ellipse seems to be in a silly place. If there's two subscriptions, that variable reference will get overwritten quite quickly. I'm sure that there should be some way we can leverage the let keyword to introduce a variable to the linq expression that will mean the correct ellipse reference is available to both the mouse move and mouse up handlers How would you write this code?

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• Asynchronous subprocess on Windows

  - by Stigma

  First of all, the overall problem I am solving is a bit more complicated than I am showing here, so please do not tell me 'use threads with blocking' as it would not solve my actual situation without a fair, FAIR bit of rewriting and refactoring. I have several applications which are not mine to modify, which take data from stdin and poop it out on stdout after doing their magic. My task is to chain several of these programs. Problem is, sometimes they choke, and as such I need to track their progress which is outputted on STDERR. pA = subprocess.Popen(CommandA, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE) # ... some more processes make up the chain, but that is irrelevant to the problem pB = subprocess.Popen(CommandB, shell=False, stdout=subprocess.PIPE, stderr=subprocess.PIPE, stdin=pA.stdout ) Now, reading directly through pA.stdout.readline() and pB.stdout.readline(), or the plain read() functions, is a blocking matter. Since different applications output in different paces and different formats, blocking is not an option. (And as I wrote above, threading is not an option unless at a last, last resort.) pA.communicate() is deadlock safe, but since I need the information live, that is not an option either. Thus google brought me to this asynchronous subprocess snippet on ActiveState. All good at first, until I implement it. Comparing the cmd.exe output of pA.exe | pB.exe, ignoring the fact both output to the same window making for a mess, I see very instantaneous updates. However, I implement the same thing using the above snippet and the read_some() function declared there, and it takes over 10 seconds to notify updates of a single pipe. But when it does, it has updates leading all the way upto 40% progress, for example. Thus I do some more research, and see numerous subjects concerning PeekNamedPipe, anonymous handles, and returning 0 bytes available even though there is information available in the pipe. As the subject has proven quite a bit beyond my expertise to fix or code around, I come to Stack Overflow to look for guidance. :) My platform is W7 64-bit with Python 2.6, the applications are 32-bit in case it matters, and compatibility with Unix is not a concern. I can even deal with a full ctypes or pywin32 solution that subverts subprocess entirely if it is the only solution, as long as I can read from every stderr pipe asynchronously with immediate performance and no deadlocks. :)

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• WPF DataTemplates with VS2010 designer support + reusable - would you do it that way?

  - by Christian

  Ok, I am currently tidying up all my old stuff. I ran into the issue of "code only DataTemplates" - which are really a pain in the ass. You can't see anything, they are really hard to design, and I want to improve my project. So I had the idea to use the following solution. The main benefits are: You have designer support for your data template You can easily include example sample data The file naming is consistent and easy to remember The preview does not require an additional XAML wrapper (even with code only controls) I will try to explain and illustrate my solution using a few pictures. I am interested in feedback, especially if you can imagine a better way to do it. And, of course, if you see any maintenance or performance issues. Ok, lets start with a simple PreviewObject. I want to have some data in it, so I create a subclass which will automatically fill in some dummy data. Then I add a list to the control, and name this list. Afterwards I add a DataTemplate, this is the sole reason for the whole control (to be able to see and edit the DataTemplate in place): Now I use this control to get my DataTemplate, to use it in other places. To make this easier, I added some code in the code behind, see here: Now I want a control to show me a list of PreviewItems, so I created a "code-only" control which creates an instance of my service (or gets one using DI in real world) and fills its list box with it: To view the result of this work, I added this control inside the same named XAML, this is basically only to be able to see the final result: What I do not like in this solution: The need to create the last control in "code only". So I tried something different while writing this post. The following two screenshots illustrate the approach. I am creating an instance of the service inside the DataContext, and I am using bindings to supply the Itemssourc and the ItemTemplate. The reason for the strange "static property" is refactoring support. If I hardcode the path in the designer (e.g. using "Path = PreviewHistory") and I refactor the names (which happens quite often, early design phase) - I screw up my controls without realizing it. Does anyone has a better idea for this? I am using Resharper, btw. Thanks for any input, and sorry for the image overkill. Just easier to explain that way.. Chris

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• Help with Linq Expression - INotifyPropertyChanged

  - by Stephen Patten

  Hello, I'm reading the source code from the latest Prism 4 drop and am interested in solving this problem. There is a base class for the ViewModels that implements INotifyPropertyChanged and INotifyDataErrorInfo and provides some refactoring friendly change notification. protected void RaisePropertyChanged<T>(Expression<Func<T>> propertyExpresssion) { var propertyName = ExtractPropertyName(propertyExpresssion); this.RaisePropertyChanged(propertyName); } private string ExtractPropertyName<T>(Expression<Func<T>> propertyExpresssion) { if (propertyExpresssion == null) { throw new ArgumentNullException("propertyExpression"); } var memberExpression = propertyExpresssion.Body as MemberExpression; if (memberExpression == null) { throw new ArgumentException("The expression is not a member access expression.", "propertyExpression"); } var property = memberExpression.Member as PropertyInfo; if (property == null) { throw new ArgumentException("The member access expression does not access property.","propertyExpression"); } if (!property.DeclaringType.IsAssignableFrom(this.GetType())) { throw new ArgumentException("The referenced property belongs to a different type.", "propertyExpression"); } var getMethod = property.GetGetMethod(true); if (getMethod == null) { // this shouldn't happen - the expression would reject the property before reaching this far throw new ArgumentException("The referenced property does not have a get method.", "propertyExpression"); } if (getMethod.IsStatic) { throw new ArgumentException("The referenced property is a static property.", "propertyExpression"); } return memberExpression.Member.Name; } and as an example of it's usage private void RetrieveNewQuestionnaire() { this.Questions.Clear(); var template = this.questionnaireService.GetQuestionnaireTemplate(); this.questionnaire = new Questionnaire(template); foreach (var question in this.questionnaire.Questions) { this.Questions.Add(this.CreateQuestionViewModel(question)); } this.RaisePropertyChanged(() => this.Name); this.RaisePropertyChanged(() => this.UnansweredQuestions); this.RaisePropertyChanged(() => this.TotalQuestions); this.RaisePropertyChanged(() => this.CanSubmit); } My question is this. What would it take to pass an array of the property names to an overloaded method (RaisePropertyChanged) and condense this last bit of code from 4 lines to 1? Thank you, Stephen

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• Issues with mx:method, mx.rpc.remoting.mxml.RemoteObject, and sub-classing mx.rpc.remoting.mxml.Remo

  - by Ryan Wilson

  I am looking to subclass RemoteObject. Instead of: <mx:RemoteObject ... > <mx:method ... /> <mx:method ... /> </mx:RemoteObject> I want to do something like: <remoting:CustomRemoteObject ...> <mx:method ... /> <mx:method ... /> </remoting:CustomRemoteObject> where CustomRemoteObject extends mx.rpc.remoting.mxml.RemoteObject like so: package remoting { import mx.rpc.remoting.mxml.RemoteObject; public class CustomRemoteObject extends RemoteObject { public function CustomRemoteObject(destination:String=null) { super(destination); } } } However, when doing so and declaring a CustomRemoteObject in MXML as above, the flex compiler shows the error: Could not resolve <mx:method> to a component implementation At first I thought it had something to do with CustomRemoteObject failing to do something, despite that (or since) it had no change except as to the name. So, I copied the source from mx.rpc.remoting.mxml.RemoteObject into CustomRemoteObject and modified it so the only difference was a refactoring of the class and package name. But still, the same error. Unlike many MXML components, I cannot cmd+click <mx:method> in FlashBuilder to open the source. Likewise, I have not found a reference in mx.rpc.remoting.mxml.RemoteObject, mx.rpc.remoting.RemoteObject, or mx.rpc.remoting.AbstractService, and have been unsuccessful in find its source online. Which leads me to the questions in the title: What exactly is <mx:method>? (yes, I know it's a declaration of a RemoteObject method, and I know how to use it, but it's peculiar in regard to other components) Why did my attempt at subclassing RemoteObject fail, despite it effectually being a rename? Perhaps the root, why can mx.rpc.remoting.mxml.RemoteObject as an MXML declaration accept <mx:method> child tags, yet the source of said class cannot when refactored in name only?

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• HttpClient response handler always returns closed stream

  - by Alex Ciminian

  I'm new to Java development so please bear with me. Also, I hope I'm not the champion of tl;dr :). I'm using HttpClient to make requests over Http (duh!) and I'd gotten it to work for a simple servlet that receives an URL as a query string parameter. I realized that my code could use some refactoring, so I decided to make my own HttpResponseHandler, to clean up the code, make it reusable and improve exception handling. I currently have something like this: public class HttpResponseHandler implements ResponseHandler<InputStream>{ public InputStream handleResponse(HttpResponse response) throws ClientProtocolException, IOException { int statusCode = response.getStatusLine().getStatusCode(); InputStream in = null; if (statusCode != HttpStatus.SC_OK) { throw new HttpResponseException(statusCode, null); } else { HttpEntity entity = response.getEntity(); if (entity != null) { in = entity.getContent(); // This works // for (int i;(i = in.read()) >= 0;) System.out.print((char)i); } } return in; } } And in the method where I make the actual request: HttpClient httpclient = new DefaultHttpClient(); HttpGet httpget = new HttpGet(target); ResponseHandler<InputStream> httpResponseHandler = new HttpResponseHandler(); try { InputStream in = httpclient.execute(httpget, httpResponseHandler); // This doesn't work // for (int i;(i = in.read()) >= 0;) System.out.print((char)i); return in; } catch (HttpResponseException e) { throw new HttpResponseException(e.getStatusCode(), null); } The problem is that the input stream returned from the handler is closed. I don't have any idea why, but I've checked it with the prints in my code (and no, I haven't used them both at the same time :). While the first print works, the other one gives a closed stream error. I need InputStreams, because all my other methods expect an InputStream and not a String. Also, I want to be able to retrieve images (or maybe other types of files), not just text files. I can work around this pretty easily by giving up on the response handler (I have a working implementation that doesn't use it), but I'm pretty curious about the following: Why does it do what it does? How do I open the stream, if something closes it? What's the right way to do this, anyway :)? I've checked the docs and I couldn't find anything useful regarding this issue. To save you a bit of Googling, here's the Javadoc and here's the HttpClient tutorial (Section 1.1.8 - Response handlers). Thanks, Alex

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• Avoiding circular project/assembly references in Visual Studio with statically typed dependency conf

  - by svnpttrssn

  First, I want to say that I am not interested in debating about any non-helpful "answers" to my question, with suggestions to putting everything in one assembly, i.e. there is no need for anyone to provide webpages such as the page titled with "Separate Assemblies != Loose Coupling". Now, my question is if it somehow (maybe with some Visual Studio configuration to allow for circular project dependencies?) is possible to use one project/assembly (I am here calling it the "ServiceLocator" assembly) for retrieving concrete implementation classes, (e.g. with StructureMap) which can be referred to from other projects, while it of course is also necessary for the the ServiceLocator itself to refer to other projects with the interfaces and the implementations ? Visual Studio project example, illustrating the kind of dependency structure I am talking about: http://img10.imageshack.us/img10/8838/testingdependencyinject.png Please note in the above picture, the problem is how to let the classes in "ApplicationLayerServiceImplementations" retrieve and instantiate classes that implement the interfaces in "DomainLayerServiceInterfaces". The goal is here to not refer directly to the classes in "DomainLayerServiceImplementations", but rather to try using the project "ServiceLocator" to retrieve such classes, but then the circular dependency problem occurrs... For example, a "UserInterfaceLayer" project/assembly might contain this kind of code: ContainerBootstrapper.BootstrapStructureMap(); // located in "ServiceLocator" project/assembly MyDomainLayerInterface myDomainLayerInterface = ObjectFactory.GetInstance<MyDomainLayerInterface>(); // refering to project/assembly "DomainLayerServiceInterfaces" myDomainLayerInterface.MyDomainLayerMethod(); MyApplicationLayerInterface myApplicationLayerInterface = ObjectFactory.GetInstance<MyApplicationLayerInterface>(); // refering to project/assembly "ApplicationLayerServiceInterfaces" myApplicationLayerInterface.MyApplicationLayerMethod(); The above code do not refer to the implementation projects/assemblies ApplicationLayerServiceImplementations and DomainLayerServiceImplementations, which contain this kind of code: public class MyApplicationLayerImplementation : MyApplicationLayerInterface and public class MyDomainLayerImplementation : MyDomainLayerInterface The "ServiceLocator" project/assembly might contain this code: using ApplicationLayerServiceImplementations; using ApplicationLayerServiceInterfaces; using DomainLayerServiceImplementations; using DomainLayerServiceInterfaces; using StructureMap; namespace ServiceLocator { public static class ContainerBootstrapper { public static void BootstrapStructureMap() { ObjectFactory.Initialize(x => { // The two interfaces and the two implementations below are located in four different Visual Studio projects x.ForRequestedType<MyDomainLayerInterface>().TheDefaultIsConcreteType<MyDomainLayerImplementation>(); x.ForRequestedType<MyApplicationLayerInterface>().TheDefaultIsConcreteType<MyApplicationLayerImplementation>(); }); } } } So far, no problem, but the problem occurs when I want to let the class "MyApplicationLayerImplementation" in the project/assembly "ApplicationLayerServiceImplementations" use the "ServiceLocator" project/assembly for retrieving an implementation of "MyDomainLayerInterface". When I try to do that, i.e. add a reference from "MyApplicationLayerImplementation" to "ServiceLocator", then Visual Studio complains about circular dependencies between projects. Is there any nice solution to this problem, which does not imply using refactoring-unfriendly string based xml-configuration which breaks whenever an interface or class or its namespace is renamed ? / Sven

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• How can I refactor out needing so many for-loops in rails?

  - by Angela

  I need help refactoring this multi-loop thing. Here is what I have: Campaign has_many Contacts Campaign also has many templates for EVent (Email, Call, and Letter). I need a list of all the Emails, Calls and Letters that are "overdue" for every Contact that belongs to a Campaign. Overdue is determined by a from_today method which looks at the date the Contact was entered in the system and the number of days that needs to pass for any given Event. from_today() outputs the number of days from today that the Event should be done for a given Contact. Here is what I've done, it works for all Emails in a Campaign across all contacts. I was going to try to create another each do loop to change the class names. Wasn't sure where to begin: named_scope, push some things into a method, etcetera, or -- minimum to be able to dynamically change the class names so at least it loops three timees across the different events rather than repeating the code three times: <% @campaigns.each do |campaign| %> <h2><%= link_to campaign.name, campaign %></h2> <% @events.each do |event| %> <%= event %> <% for email in campaign.emails %> <h4><%= link_to email.title, email %> <%= email.days %> days</h4> <% for contact in campaign.contacts.find(:all, :order => "date_entered ASC" ) %> <% if (from_today(contact, email.days) < 0) %> <% if show_status(contact, email) == 'no status'%> <p> <%= full_name(contact) %> is <%= from_today(contact,email.days).abs%> days overdue: <%= do_event(contact, email) %> </p> <% end %> <% end %> <% end %> <% end %> <% end %> <% end %>

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• Looking for RESTful Suggestions In Porting ASP.NET to MVC.NET

  - by DaveDev

  I've been tasked with porting/refactoring a Web Application Platform that we have from ASP.NET to MVC.NET. Ideally I could use all the existing platform's configurations to determine the properties of the site that is presented. Is it RESTful to keep a SiteConfiguration object which contains all of our various page configuration data in the System.Web.Caching.Cache? There are a lot of settings that need to be loaded when the user acceses our site so it's inefficient for each user to have to load the same settings every time they access. Some data the SiteConfiguration object contains is as follows and it determines what Master Page / site configuration / style / UserControls are available to the client, public string SiteTheme { get; set; } public string Region { private get; set; } public string DateFormat { get; set; } public string NumberFormat { get; set; } public int WrapperType { private get; set; } public string LabelFileName { get; set; } public LabelFile LabelFile { get; set; } // the following two are the heavy ones // PageConfiguration contains lots of configuration data for each panel on the page public IList<PageConfiguration> Pages { get; set; } // This contains all the configurations for the factsheets we produce public List<ConfiguredFactsheet> ConfiguredFactsheets { get; set; } I was thinking of having a URL structure like this: www.MySite1.com/PageTemplate/UserControl/ the domain determines the SiteConfiguration object that is created, where MySite1.com is SiteId = 1, MySite2.com is SiteId = 2. (and in turn, style, configurations for various pages, etc.) PageTemplate is the View that will be rendered and simply defines a layout for where I'm going to inject the UserControls Can somebody please tell me if I'm completely missing the RESTful point here? I'd like to refactor the platform into MVC because it's better to work in but I want to do it right but with a minimum of reinventing-the-wheel because otherwise it won't get approval. Any suggestions otherwise? Thanks

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• LINQ Query returns false when it should be true.

  - by deliriousDev

  I have the following LINQ query written by a former developer and it isn't working when it should. public bool IsAvailable(Appointment appointment) { var appointments = _appointmentRepository.Get; var shifts = _scheduleRepository.Get; var city = _customerRepository.Find(appointment.CustomerId).City ?? appointment.Customer.City; const int durationHour = 1; DateTime scheduledEndDate = appointment.ScheduledTime.Add(new TimeSpan(durationHour, 0, 0)); var inWorkingHours = shifts .Where(x => //Check if any available working hours x.Employee.City == city && x.ShiftStart <= appointment.ScheduledTime && x.ShiftEnd >= scheduledEndDate && //check if not booked yet !appointments .Where(a => (appointment.Id == 0 || a.Id != appointment.Id) && a.Employee.Id == x.Employee.Id && ( (a.ScheduledTime <= appointment.ScheduledTime && appointment.ScheduledTime <= EntityFunctions.AddHours(a.ScheduledTime, durationHour)) || (a.ScheduledTime <= scheduledEndDate && scheduledEndDate <= EntityFunctions.AddHours(a.ScheduledTime, durationHour)) )) .Select(a => a.Employee.Id) .Contains(x.Employee.Id) ); if (inWorkingHours.Any()) { var assignedEmployee = inWorkingHours.FirstOrDefault().Employee; appointment.EmployeeId = assignedEmployee.Id; appointment.Employee = assignedEmployee; return true; } return false; } The query is suppose to handle the following scenarios Given An Appointment With A ScheduledTime Between A ShiftStart and ShiftEnd time But Does not match any employees in same city - (Return true, Assign as "Unassigned") Given An Appointment With A ScheduledTime Between A ShiftStart and ShiftEnd time AND Employee for that shift is in the same city as the customer (Return True AND Assign to the employee) If the customer is NOT in the same city as an employee we assign the appointment as "Unassigned" as along as the scheduledTime is within an of the employees shift start/end times If the customer is in the same city as an employee we assign the appointment to one of the employees (firstOrdefault) and occupy that timeslot. Appointments CAN NOT overlap (Assigned Ones). Unassigned can't overlap each other. This query use to work (I've been told). But now it doesn't and I have tried refactoring it and various other paths with no luck. I am now on week two and just don't know where the issue in the query is or how to write it. Let me know if I need to post anything further. I have verified appointments, shifts, city all populate with valid data so the issue doesn't appear to be with null or missing data.

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• how to use window.onload?

  - by Patrick

  I'm refactoring a website using MVC. What was a set of huge pages with javascript, php, html etc etc is becoming a series of controllers and views. I'm trying to do it in a modular way so views are split in 'modules' that I can reuse in other pages when needed eg. "view/searchform displays only one div with the searchform "view/display_events displays a list of events and so on. One of the old pages was supposed to load a google map with a marker on it. Amongst the rest of the code, I can identify the relevant bits as follows <head> <script src="http://maps.google.com/maps?file=api&amp;v=2&amp;key=blablabla" type="text/javascript"></script> <script type="text/javascript"> //<![CDATA[ function load() { if (GBrowserIsCompatible()) { var map = new GMap2(document.getElementById("map")); var point = new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>); map.setCenter(new GLatLng(<?php echo ($info->lat && $info->lng) ? $info->lat .",". $info->lng : "51.502759,-0.126171"; ?>), 15); map.addControl(new GLargeMapControl()); map.addControl(new GScaleControl()); map.addOverlay(new GMarker(point)); var marker = createMarker(point,GIcon(),"CIAO"); map.addOverlay(marker); } } //]]> </script> </head> ...then <body onload="load()" onunload="GUnload()"> ...and finally this div where the map should be displayed <div id="map" style="width: 440px; height: 300px"> </div> Don't know much about js, but my understanding is that a) I have to include the scripts in the view module I'm writing (directly in the HTML? I would prefer to load a separate script) b) I have to trigger that function using the equivalent of body onload... (obviously there's no body tag in my view. In my ignorance I've tried div onload=.... but didn't seem to be working :) What do you suggest I do? I've read about window.onload but don't know what's the correct syntax for that. please keep in mind that other parts of the page include other js functions (eg, google adsense) that are called after the footer.

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• How do I use Ruby metaprogramming to refactor this common code?

  - by James Wenton

  I inherited a project with a lot of badly-written Rake tasks that I need to clean up a bit. Because the Rakefiles are enormous and often prone to bizarre nonsensical dependencies, I'm simplifying and isolating things a bit by refactoring everything to classes. Specifically, that pattern is the following: namespace :foobar do desc "Frozz the foobar." task :frozzify do unless Rake.application.lookup('_frozzify') require 'tasks/foobar' Foobar.new.frozzify end Rake.application['_frozzify'].invoke end # Above pattern repeats many times. end # Several namespaces, each with tasks that follow this pattern. In tasks/foobar.rb, I have something that looks like this: class Foobar def frozzify() # The real work happens here. end # ... Other tasks also in the :foobar namespace. end For me, this is great, because it allows me to separate the task dependencies from each other and to move them to another location entirely, and I've been able to drastically simplify things and isolate the dependencies. The Rakefile doesn't hit a require until you actually try to run a task. Previously this was causing serious issues because you couldn't even list the tasks without it blowing up. My problem is that I'm repeating this idiom very frequently. Notice the following patterns: For every namespace :xyz_abc, there is a corresponding class in tasks/... in the file tasks/[namespace].rb, with a class name that looks like XyzAbc. For every task in a particular namespace, there is an identically named method in the associated namespace class. For example, if namespace :foo_bar has a task :apples, you would expect to see def apples() ... inside the FooBar class, which itself is in tasks/foo_bar.rb. Every task :t defines a "meta-task" _t (that is, the task name prefixed with an underscore) which is used to do the actual work. I still want to be able to specify a desc-description for the tasks I define, and that will be different for each task. And, of course, I have a small number of tasks that don't follow the above pattern at all, so I'll be specifying those manually in my Rakefile. I'm sure that this can be refactored in some way so that I don't have to keep repeating the same idiom over and over, but I lack the experience to see how it could be done. Can someone give me an assist?

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• PyGTK: Radiobuttons are still displayed after removal

  - by canavanin

  Hi everyone! I am using PyGTK and the gtk.assistant. On one page I would like to display two radiobuttons in case the user selected a certain option on a previous page. The labels of the buttons - and whether the buttons are to be present at all - are to depend entirely on that earlier selection. Furthermore, if the user goes back and changes that selection, the page containing the radiobuttons is to be updated accordingly. I have got as far as having the radiobuttons displayed when necessary, and with the correct labels. The trouble is that if I go back and change the determining selection, or if I move one page further than the 'radiobutton page' and then move back, the buttons are not only not removed (in case that would have been required), their number has also doubled. To show you what I'm doing, here's part of my code (I've left out bits that do unrelated things, that's why the function name doesn't fit). The function is called when the "prepare" signal is emitted prior to construction of the 'radiobutten page'. def make_class_skills_treestore(self): print self.trained_by_default_hbox.get_children() # PRINT 1 for child in self.trained_by_default_hbox.get_children(): if type(child) == gtk.RadioButton: self.trained_by_default_hbox.remove(child) #child.destroy() # <-- removed the labels, but not the buttons print self.trained_by_default_hbox.get_children() # PRINT 2 class_skills = self.data.data['classes'][selected_class].class_skills.values() default_trained_count = (class_skills.count([True, True]) , class_skills.count([True, False])) num_default_trained_skills = default_trained_count[1] / 2 # you have to pick one of a pair --> don't # count each as trained by default for i in range(default_trained_count[0]): # those are trained by default --> no choice num_default_trained_skills +=1 selected_class = self.get_classes_key_from_class_selection() if default_trained_count[1]: for skill in self.data.data['classes'][selected_class].class_skills.keys(): if self.data.data['classes'][selected_class].class_skills[skill] == [ True, False ] and not self.default_radio: self.default_radio.append(gtk.RadioButton(group=None, label=skill)) elif self.data.data['classes'][selected_class].class_skills[skill] == [ True, False ] and self.default_radio: self.default_radio.append(gtk.RadioButton(group=self.default_radio[0], label=skill)) if self.default_radio: for radio in self.default_radio: self.trained_by_default_hbox.add(radio) self.trained_by_default_hbox.show_all() self.trained_by_default_hbox and self.trained_by_default_label, as well as self.default_radio stem from the above function's class. I have two print statements (PRINT 1 and PRINT 2) in there for debugging. Here's what they give me: PRINT 1: [<gtk.Label object at 0x8fc4c84 (GtkLabel at 0x90a2f20)>, <gtk.RadioButton object at 0x8fc4d4c (GtkRadioButton at 0x90e4018)>, <gtk.RadioButton object at 0x8fc4cac (GtkRadioButton at 0x90ceec0)>] PRINT 2: [<gtk.Label object at 0x8fc4c84 (GtkLabel at 0x90a2f20)>] So the buttons have indeed been removed, yet they still show up on the page. I know the code requires some refactoring, but first I'd like to get it to work at all... If someone could help me out that would be great! Thanks a lot in advance for your replies - any kind of help is highly appreciated.

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