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  • Displaying device contacts with an indication that the contact is registered to the app

    - by Prasanna Aarthi
    We are developing a mobile app that needs to pick up device contacts, display them and indicate if the contact has already registered with this app. We have our DB in the server and the app fetches data using web services. What will be the best approach to implement the above scenario taking performance into consideration. Option 1: Every time user opens the app,fetch the contacts and send the list of email addresses to the server, check with the registered email ids and return the list of registered users in the contact list. In this approach whenever user opens the particular page, he needs to wait for few seconds to load data, but the contacts will be the latest from the device. Option 2: First time when the user opens the app, fetch contacts ,send the entire list of contacts and save it in the DB, retrieve list of registered users in the contacts then save this to local DB. From now on, data will be fetched from local DB and displayed. When a new user registers in the app, again check with records in central DB and send list of new users who are in your contacts that have registered to your app. This list will be added to local DB. and the process continues. In this case the new contacts added by user will not be updated in the app but retrieval and display of records would be quick. What would be the correct approach? In case there is a better way of doing this, please let me know.

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  • Euler Problem 1 : Code Optimization / Alternatives [on hold]

    - by Sudhakar
    I am new bee into the world of Datastructures and algorithms from ground up. This is my attempt to learn. If the question is very plain/simple . Please bear with me. Problem: Find the sum of all the multiples of 3 or 5 below 1000. Code i worte: package problem1; public class Problem1 { public static void main(String[] args) { //******************Approach 1**************** long start = System.currentTimeMillis(); int total = 0; int toSubtract = 0; //Complexity N/3 int limit = 10000; for(int i=3 ; i<limit ;i=i+3){ total = total +i; } //Complexity N/5 for(int i=5 ; i<limit ;i=i+5){ total = total +i; } //Complexity N/15 for(int i=15 ; i<limit ;i=i+15){ toSubtract = toSubtract +i; } //9N/15 = 0.6 N System.out.println(total-toSubtract); System.out.println("Completed in "+(System.currentTimeMillis() - start)); //******************Approach 2**************** for(int i=3 ; i<limit ;i=i+3){ total = total +i; } for(int i=5 ; i<limit ;i=i+5){ if ( 0 != (i%3)) total = total +i; } } } Question 1 - Which best approach from the above code and why ? 2 - Are there any better alternatives ?

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  • How to handle URLs with diacritic characters

    - by user359650
    I am wondering how to handle URLs which correspond to strings containing diacritic (á, u, ´...). I believe what we're seeing mostly are URLs where diacritic characters where converted to their closest ASCII equivalent, for instance Rånades på Skyttis i Ö-vik converted to ranades-pa-skyttis-i-o-vik. However depending on the corresponding language, such conversion might be incorrect. For instance in German, ü should be converted to ue and not just u, as seen with the below URL representing the Bayern München string as bayern-muenchen: http://www.bundesliga.de/en/liga/clubs/fc-bayern-muenchen/index.php However what I've also noticed, is that browsers can render non-ASCII characters when they are percent-encoded in the URL, which is the approach Wikipedia has chosen, for instance http://de.wikipedia.org/wiki/FC_Bayern_M%C3%BCnchen which is rendered as: Therefore I'm considering the following approach for creating URL slugs: -(1) convert strings while replacing non-ASCII characters to their recommended ASCII representation: Bayern München - bayern-muenchen -(2) also convert strings to percent encoding: Bayern München - bayern_m%C3%BCnchen -create a 301 redirect from version (1) to version (2) Version (1) URLs could be used for marketing purposes (e.g. mywebsite.com/bayern-muenchen) but the URLs that would end being displayed in the browser bar would be version (2) URLs (e.g. mywebsite.com/bayern-münchen). Can you foresee particular problems with this approach? (Wikipedia is not doing it and I wonder why, apart from the fact that they don't need to market their URLs)

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  • Special Value Sets in Oracle Applications

    - by Manoj Madhusoodanan
    Here I am going to explain Special Value Sets in Oracle Applications.I have a requirement in which I want to execute a BIP report with some parameters. The first parameter Current Month should allow only MON-YYYY format.Schedule Start Date and Schedule End Date should be with in first parameter month. Approach 1If the report is through PL/SQL Stored Procedure executable the we can do all the validation in backend. Approach 2Second approach is through Special Value Sets.This value set has events like Edit,Load and Validate.We can attach PL/SQL code snippet to each event.Here I am going to attach validation routine to Validate event to validate the user input.Validate event fires when the focus leaves from the item. Here I am going to create two special value sets ( one for first parameter and another for the second and third parameter). Value Set 1Name : XXCUST_CURRENT_MONTHList Type : List of ValuesFormat Type : CharMaximum Size : 8Validation Type : SpecialEvent : ValidateFunction : XXCUST_CURRENT_MONTH_VALIDATE_ROUTINEValue Set 2Name : XXCUST_DATESList Type : List of ValuesFormat Type : Standard DateValidation Type : SpecialEvent : ValidateFunction : XXCUST_DATES_VALIDATE_ROUTINE Note: Inside the validate routine I am using FND messages.Generate message file also using "FNDMDGEN apps/password 0 Y US XXCUST DB_TO_RUNTIME". Attach XXCUST_CURRENT_MONTH to first parameter.Also XXCUST_DATES to second and third parameter. Note: Since the program is using Special Value Sets it can be submit only through Oracle Forms.Submission through OA Framework and PL/SQL APIs are not recommended. OutputGive Current Date as 01-2012 Give Schedule Start Date out of current month.

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  • Agile project management, agile development: early integration

    - by Matías Fidemraizer
    I believe that agile works if everything is agile. In software development area, in my opinion, if team members' code is integrated early, code will be more in sync and this has a lot of pros: Early integration helps team members to avoid painful merges. Encourages better coding habits, because everyone makes sure that they don't break co-workers' code everyday. Both developers and architects (code reviewers) may detect bad design decisions or just wrong development directions in real-time, preventing useless work. Actually I'm talking about getting the latest version of code base and checking-in your own code to the source control in a daily basis. When you start your coding day (i.e. you arrive to your work), your first action is updating your code base with the latest version from the source control. In the other hand, when you're about an hour to leave from your work and go home, your last action is checking-in your code to the source control and be sure that your day work doesn't break the project's build process. Rather than updating and checking-in your code once you finished an entire task, I believe the best approach is fixing small and flexible personal milestones and checking-in the code once you finish one of these. I really believe that this coding approach fits better in the agile project management concept. Do you know some document, blog post, wiki, article or whatever that you can suggest me that could be in sync with my opinion?. And, do you find any problem working with this approach?. Thank you in advance.

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  • Converting a bounded knapsack problem to 0/1 knapsack problem

    - by Ants
    I ran across a problem where goal was to use dynamic programming (instead of other approaches). There is a distance to be spanned, and a set of cables of different lengths. What is the minimum number of cables needed to span the distance exactly? To me this looked like a knapsack problem, but since there could be multiples of a particular length, it was a bounded knapsack problem, rather than a 0/1 knapsack problem. (Treat the value of each item to be its weight.) Taking the naive approach (and not caring about the expansion of the search space), the method I used to convert the bounded knapsack problem into a 0/1 knapsack problem, was simply break up the multiples into singles and apply the well-known dynamic programming algorithm. Unfortunately, this leads to sub-optimal results. For example, given cables: 1 x 10ft, 1 x 7ft, 1 x 6ft, 5 x 3ft, 6 x 2ft, 7 x 1ft If the target span is 13ft, the DP algorithm picks 7+6 to span the distance. A greedy algorithm would have picked 10+3, but it's a tie for minimum number of cables. The problem arises, when trying to span 15ft. The DP algorithm ended up picking 6+3+3+3 to get 4 cables, while the greedy algorithm correctly picks 10+3+2 for only 3 cables. Anyway, doing some light scanning of converting bounded to 0/1, it seems like the well-known approach to convert multiple items to { p, 2p, 4p ... }. My question is how does this conversion work if p+2p+4p does not add up to the number of multiple items. For example: I have 5 3ft cables. I can't very well add { 3, 2x3, 4x3 } because 3+2x3+4x3 5x3. Should I add { 3, 4x3 } instead? [I'm currently trying to grok the "Oregon Trail Knapsack Problem" paper, but it currently looks like the approach used there is not dynamic programming.]

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  • PCI Compliance Book Suggestion

    - by Joel Weise
    I am always looking for good books on security, compliance and of course, PCI.  Here is one I think you will find very useful. "PCI Compliance, Third Edition: Understand and Implement Effective PCI Data Security Standard Compliance" by Branden Williams and Anton Chuvakin.  [Fair disclosure - Branden and I work together on the Information Systems Security Association Journal's editorial board.]   The primary reason I like this book is that the authors take a holistic architectural approach to PCI compliance and that to me is the most safe and sane way to approach PCI.  Using such an architectural approach to PCI is, in my humble opinion, the underlying intent of PCI.  Don't create a checklist of the PCI DSS and then map a solution to each.  That is a recipe for disaster.  Instead, look at how the different components and their configurations work together in a synergistic fashion.  In short, create a security architecture and governance framework (the ISO 27000 series is a good place to start) that begins with an evaluation of the requirements laid down in the PCI DSS, as well as your other applicable compliance, business and technical requirements.  By developing an integrated security architecture you should be able to not only address current requirements, but also be in a position to quickly address future ones as well.

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  • How can Agile methodologies be adapted to High Volume processing system development?

    - by luckyluke
    I am developing high volume processing systems. Like mathematical models that calculate various parameters based on millions of records, calculated derived fields over milions of records, process huge files having transactions etc... I am well aware of unit testing methodologies and if my code is in C# I have no problem in unit testing it. Problem is I often have code in T-SQL, C# code that is a SQL stored assembly, and SSIS workflow with a good amount of logic (and outcomes etc) or some SAS process. What is the approach YOu use when developing such systems. I usually develop several tests as Stored procedures in a designed schema(TEST) and then automatically run them overnight and check out the results. But this is only for T-SQL. And Continous integration IS hard. But the problem is with testing SSIS packages. How do You test it? What is Your preferred approach for stubbing data into tables (especially if You need a lot data initialization). I have some approach derived over the years but maybe I am just not reading enough articles. So Banking, Telecom, Risk developers out there. How do You test your mission critical apps that process milions of records at end day, month end etc? What frameworks do You use? How do You validate that Your ssis package is Correct (as You develop it)/ How do You achieve continous integration in such an environment (Personally I never got there)? I hope this is not to open-ended question. How do You test Your map-reduce jobs for example (i do not use hadoop but this is quite similar). luke Hope that this is not too open ended

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  • Iterative and Incremental Principle Series 1: The Dreaded Assignment

    - by llowitz
    A few days ago, while making breakfast for my teenage son… he turned to me and happily exclaimed, “I really like how my high school Government class assigns our reading homework.  In middle school, we had to read a chapter each week.  Everyone dreaded it.  In high school, our teacher assigns us a section or two every day.  We still end up reading a chapter each week, but this way is so much easier and I’m actually remembered what I’ve read!” Wow!  Once I recovered from my initial shock that my high school son actually initiated conversation with me, it struck me that he was describing one of the five basic OUM principles -- Iterative and Incremental.   Not only did he describe how his teacher divided a week long assignment into daily increments, but he went on to communicate some of the major benefits of having shorter, more achievable milestones.  I started to think about other applications of the iterative and incremental approach and I realized that I had incorporated this approach when I recently rededicated myself to physical fitness.  Join me over the next four days as I present an Iterative and Incremental blog series where I relate my personal experience incorporating the iterative and incremental approach and the benefits that I achieved.

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  • Loadbalancing Questions

    - by Van Holtz
    I have been learning networking for about 4 months. Wrote a single standalone Multiplayer server and succeeded with authoritative approach. Now I want to extend it by splitting the single server into clusters to allow even more players to log in to avoid latency issues. Now I have protyped the Loadbalancing server and its running pretty good so far. This is my architecture, I have a master server which acts as a proxy, every sub servers(chat, login, game) connect to the master server as well as all the clients. when a client connects, Client Request: Send Request - MS(Master) - Decides which SS(SubServer) to forward to - Forwards Request to SS - SS - Analyze Message - Send Response to MS - Decides which Client to forward to - Forwards Response to Client Well, it looks like its going through lots of stages. it takes double the time to process the message than a single server approach. i feel like my model isnt the best or i may be wrong. is there any better model or the one they use in professional games? I still want a Master-SubServer approach. I just want to clarify that I'm going in the right direction before writing all my codes. Thanks for any answer :)

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  • Multi Threading - How to split the tasks

    - by Motig
    if I have a game engine with the basic 'game engine' components, what is the best way to 'split' the tasks with a multi-threaded approach? Assuming I have the standard components of: Rendering Physics Scripts Networking And a quad-core, I see two ways of multi-threading: Option A ('Vertical'): Using this approach I can allow one core for each component of the engine; e.g. one core for the Rendering task, one for the Physics, etc. Advantages: I do not need to worry about thread-safety within each component I can take advantage of special optimizations provided for single-threaded access (e.g. DirectX offers a flag that can be set to tell it that you will only use single-threading) Option B ('Horizontal'): Using this approach, each task may be split up into 1 <= n <= numCores threads, and executed simultaneously, one after the other. Advantages: Allows for work-sharing, i.e. each thread can take over work still remaining as the others are still processing I can take advantage of libraries that are designed for multi-threading (i.e. ... DirectX) I think, in retrospect, I would pick Option B, but I wanted to hear you guys' thoughts on the matter.

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  • XML Rules Engine and Validation Tutorial with NIEM

    - by drrwebber
    Our new XML Validation Framework tutorial video is now available. See how to easily integrate code-free adaptive XML validation services into your web services using the Java CAMV validation engine. CAMV allows you to build fault tolerant content checking with XPath that optionally use SQL data lookups. This can provide warnings as well as error conditions to tailor your validation layer to exactly meet your business application needs. Also available is developing test suites using Apache ANT scripting of validations.  This allows a community to share sets of conformance checking test and tools . On the technical XML side the video introduces XPath validation rules and illustrates and the concepts of XML content and structure validation. CAM validation templates allow contextual parameter driven dynamic validation services to be implemented compared to using a static and brittle XSD schema approach.The SQL table lookup and code list validation are discussed and examples presented.Features are highlighted along with a demonstration of the interactive generation of actual live XML data from a SQL data store and then validation processing complete with errors and warnings detection.The presentation provides a primer for developing web service XML validation and integration into a SOA approach along with examples and resources. Also alignment with the NIEM IEPD process for interoperable information exchanges is discussed along with NIEM rules services.The CAMV engine is a high performance scalable Java component for rapidly implementing code-free validation services and methods. CAMV is a next generation WYSIWYG approach that builds from older Schematron coding based interpretative runtime tools and provides a simpler declarative metaphor for rules definition. See: http://www.youtube.com/user/TheCAMeditor

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  • Binding in the view or the controller?

    - by da_b0uncer
    I've seen 2 different approaches with MVC on the web. One, like in ExtJS, is to bind the callbacks to the view via the controller. Finding every element on the view and adding the functionallity. The other, like in angular.js and in the lift-framework server-side, too, is to bind in the views and just write the functionallity in the controller. Which is better and cleaner? The ExtJS approach has dumb views and all the logic in the controller. Which seems clean to me. I had problems with global IDs for GUI-elements or relative navigation to GUI-elements in this approach. When I changed the view, the controller couldn't find the buttons anymore or I had multiple instances of one button with the same ID on a single application, because of the global ID. But I solved this with IDs that are only global in a view and can be on the application multiple times. So I could mess with the (dumb) views layout and design and the functionallity wouldn't break. The angular.js approach with the bindings in the view don't has the problem with global IDs. Also, the person who changes something in the view layout has to know the IDs anyway, so the controller can put the data at the right spot. So if I write <a ng-click="doThis()" /> for angular.js and implement doThis() or <a lid="buttonwhichdoesthis" /> for extjs and find the element with the local id and add doThis() as handler on the controller side, seems to be not so different. The only thing is, the second one has one more layer of indirection, which seems cleaner. The first one seems somehow to cost less effort.

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  • How can I do vertical paging with UITableView?

    - by vodkhang
    Let me describe the situation I am trying to do: I have a list of Items. When I go into ItemDetailView, which is a UITableView. I want to do paging here like: When I scroll down out of the table view, I want to display the next item. Like in Good Reader: Currently, I am trying 2 approaches but both do not really work for me. 1st: I let my UITableView over my scroll view and I have a nice animation and works quite ok except sometimes, the UITableView will receive event instead of my scroll view. And because, a UITableView is already a UITableView, this approach seems not be a good idea. Here is some code: - (void)applicationDidFinishLaunching:(UIApplication *)application { // a page is the width of the scroll view scrollView.pagingEnabled = YES; scrollView.contentSize = CGSizeMake(scrollView.frame.size.width, scrollView.frame.size.height * kNumberOfPages); scrollView.showsHorizontalScrollIndicator = NO; scrollView.showsVerticalScrollIndicator = YES; scrollView.scrollsToTop = NO; scrollView.delegate = self; [self loadScrollViewWithPage:0]; } - (void)loadScrollViewWithPage:(int)page { if (page < 0) return; if (page >= kNumberOfPages) return; [self.currentViewController.view removeFromSuperview]; self.currentViewController = [[[MyNewTableView alloc]initWithPageNumber:page] autorelease]; if (nil == currentViewController.view.superview) { CGRect frame = scrollView.frame; [scrollView addSubview:currentViewController.view]; } } - (void)scrollViewDidScroll:(UIScrollView *)sender { if (pageControlUsed) { return; } CGFloat pageHeight = scrollView.frame.size.height; int page = floor((scrollView.contentOffset.y - pageHeight / 2) / pageHeight) + 1; [self loadScrollViewWithPage:page]; } - (IBAction)changePage:(id)sender { int page = pageControl.currentPage; [self loadScrollViewWithPage:page]; // update the scroll view to the appropriate page CGRect frame = scrollView.frame; [scrollView scrollRectToVisible:frame animated:YES]; pageControlUsed = YES; } My second approach is: using pop and push of navigationController to pop the current ItemDetail and push a new one on top of it. But this approach will not give me a nice animation of scrolling down like the first approach. So, the answer to how I can get it done with either approach will be appreciated

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  • Objective-C wrapper API design methodology

    - by Wade Williams
    I know there's no one answer to this question, but I'd like to get people's thoughts on how they would approach the situation. I'm writing an Objective-C wrapper to a C library. My goals are: 1) The wrapper use Objective-C objects. For example, if the C API defines a parameter such as char *name, the Objective-C API should use name:(NSString *). 2) The client using the Objective-C wrapper should not have to have knowledge of the inner-workings of the C library. Speed is not really any issue. That's all easy with simple parameters. It's certainly no problem to take in an NSString and convert it to a C string to pass it to the C library. My indecision comes in when complex structures are involved. Let's say you have: struct flow { long direction; long speed; long disruption; long start; long stop; } flow_t; And then your C API call is: void setFlows(flow_t inFlows[4]); So, some of the choices are: 1) expose the flow_t structure to the client and have the Objective-C API take an array of those structures 2) build an NSArray of four NSDictionaries containing the properties and pass that as a parameter 3) create an NSArray of four "Flow" objects containing the structure's properties and pass that as a parameter My analysis of the approaches: Approach 1: Easiest. However, it doesn't meet the design goals Approach 2: For some reason, this seems to me to be the most "Objective-C" way of doing it. However, each element of the NSDictionary would have to be wrapped in an NSNumber. Now it seems like we're doing an awful lot just to pass the equivalent of a struct. Approach 3: Seems the cleanest to me from an object-oriented standpoint and the extra encapsulation could come in handy later. However, like #2, it now seems like we're doing an awful lot (creating an array, creating and initializing objects) just to pass a struct. So, the question is, how would you approach this situation? Are there other choices I'm not considering? Are there additional advantages or disadvantages to the approaches I've presented that I'm not considering?

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  • Why does one loop take longer to detect a shared memory update than another loop?

    - by Joseph Garvin
    I've written a 'server' program that writes to shared memory, and a client program that reads from the memory. The server has different 'channels' that it can be writing to, which are just different linked lists that it's appending items too. The client is interested in some of the linked lists, and wants to read every node that's added to those lists as it comes in, with the minimum latency possible. I have 2 approaches for the client: For each linked list, the client keeps a 'bookmark' pointer to keep its place within the linked list. It round robins the linked lists, iterating through all of them over and over (it loops forever), moving each bookmark one node forward each time if it can. Whether it can is determined by the value of a 'next' member of the node. If it's non-null, then jumping to the next node is safe (the server switches it from null to non-null atomically). This approach works OK, but if there are a lot of lists to iterate over, and only a few of them are receiving updates, the latency gets bad. The server gives each list a unique ID. Each time the server appends an item to a list, it also appends the ID number of the list to a master 'update list'. The client only keeps one bookmark, a bookmark into the update list. It endlessly checks if the bookmark's next pointer is non-null ( while(node->next_ == NULL) {} ), if so moves ahead, reads the ID given, and then processes the new node on the linked list that has that ID. This, in theory, should handle large numbers of lists much better, because the client doesn't have to iterate over all of them each time. When I benchmarked the latency of both approaches (using gettimeofday), to my surprise #2 was terrible. The first approach, for a small number of linked lists, would often be under 20us of latency. The second approach would have small spats of low latencies but often be between 4,000-7,000us! Through inserting gettimeofday's here and there, I've determined that all of the added latency in approach #2 is spent in the loop repeatedly checking if the next pointer is non-null. This is puzzling to me; it's as if the change in one process is taking longer to 'publish' to the second process with the second approach. I assume there's some sort of cache interaction going on I don't understand. What's going on?

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  • Having trouble getting MEF imports to be resolved

    - by Dave
    This is sort of a continuation of one of my earlier posts, which involves the resolving of modules in my WPF application. This question is specifically related to the effect of interdependencies of modules and the method of constructing those modules (i.e. via MEF or through new) on MEF's ability to resolve relationships. First of all, here is a simple UML diagram of my test application: I have tried two approaches: left approach: the App implements IError right approach: the App has a member that implements IError Left approach My code behind looked like this (just the MEF-related stuff): // app.cs [Export(typeof(IError))] public partial class Window1 : Window, IError { [Import] public CandyCo.Shared.LibraryInterfaces.IPlugin Plugin { get; set; } [Export] public CandyCo.Shared.LibraryInterfaces.ICandySettings Settings { get; set; } private ICandySettings Settings; public Window1() { // I create the preferences here with new, instead of using MEF. I wonder // if that's my whole problem? If I use MEF, and want to have parameters // going to the constructor, then do I have to [Export] a POCO (i.e. string)? Settings = new CandySettings( "Settings", @"c:\settings.xml"); var catalog = new DirectoryCatalog( "."); var container = new CompositionContainer( catalog); try { container.ComposeParts( this); } catch( CompositionException ex) { foreach( CompositionError e in ex.Errors) { string description = e.Description; string details = e.Exception.Message; } throw; } } } // plugin.cs [Export(typeof(IPlugin))] public class Plugin : IPlugin { [Import] public CandyCo.Shared.LibraryInterfaces.ICandySettings CandySettings { get; set; } [Import] public CandyCo.Shared.LibraryInterfaces.IError ErrorInterface { get; set; } [ImportingConstructor] public Plugin( ICandySettings candy_settings, IError error_interface) { CandySettings = candy_settings; ErrorInterface = error_interface; } } // candysettings.cs [Export(typeof(ICandySettings))] public class CandySettings : ICandySettings { ... } Right-side approach Basically the same as the left-side approach, except that I created a class that inherits from IError in the same assembly as Window1. I then used an [Import] to try to get MEF to resolve that for me. Can anyone explain how the two ways I have approached MEF here are flawed? I have been in the dark for so long that instead of reading about MEF and trying different suggestions, I've added MEF to my solution and am stepping into the code. The part where it looks like it fails is when it calls partManager.GetSavedImport(). For some reason, the importCache is null, which I don't understand. All the way up to this point, it's been looking at the part (Window1) and trying to resolve two imported interfaces -- IError and IPlugin. I would have expected it to enter code that looks at other assemblies in the same executable folder, and then check it for exports so that it knows how to resolve the imports...

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  • Rails / ActiveRecord Modeling Help

    - by JM
    I’m trying to model a relationship in ActiveRecord and I think it’s a little beyond my skill level. Here’s the background. This is a horse racing project and I’m trying to model a horses Connections over time. Connections are defined as the Horse’s Current: Owner, Trainer and Jockey. Over time, a horse’s connections can change for a lot of different reasons: The owner sells the horse in a private sale The horse is claimed (purchase in a public sale) The Trainer switches jockeys The owner switches trainers In my first attempt at modeling this, I created the following tables: Horses, Owners, Trainers, Jockeys and Connections. Essentially, the Connections table was the has-many-through join table and was structured as follows: Connections Table 1 Id Horse_id Owner_id Trainer_id Jockey_id Status_Code Status_Date Change_Code The Horse, Owner, Trainer and Jockey foreign keys are self explanatory. The status code is 1 or 0 (1 active, 0 inactive) and the status date is the date the status changed. Change_code is and integer or string value that represent the reason for the change (private sale, claim, jockey change, etc) The key benefit of this approach is that the Connection is represented as one record in the connections table. The downside is that I have to have a table for Owner (1), Trainer (2) and Jockey (3) when one table could due. In my second attempt at modeling this I created the following tables: Horses, Connections, Entities The Entities tables has the following structure Entities Table id First_name Last_name Role where Role represents if the entity is a Owner, Trainer or Jockey. Under this approach, my Connections table has the following structure Connections Table 2 id Horse_id Entity_id Role Status_Code Status_Date Change_Code 1 1 1 1 1 1/1/2010 2 1 4 2 1 1/1/2010 3 1 10 3 1 1/1/2010 This approach has the benefit of eliminating two tables, but on the other hand the Connection is now comprised of three different records as opposed to one in the first approach. What believe I’m looking for is an approach that allows me to capture the Connection in one record, but also uses an Entities table with roles instead of the Owner, Trainer and Jockey tables. I’m new to ActiveRecord and rails so any and all input would be greatly appreciated. Perhaps there are other ways that would even be better. Thanks!

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  • Where’s my MD.050?

    - by Dave Burke
    A question that I’m sometimes asked is “where’s my MD.050 in OUM?” For those not familiar with an MD.050, it serves the purpose of being a Functional Design Document (FDD) in one of Oracle’s legacy Methods. Functional Design Documents have existed for many years with their primary purpose being to describe the functional aspects of one or more components of an IT system, typically, a Custom Extension of some sort. So why don’t we have a direct replacement for the MD.050/FDD in OUM? In simple terms, the disadvantage of the MD.050/FDD approach is that it tends to lead practitioners into “Design mode” too early in the process. Whereas OUM encourages more emphasis on gathering, and describing the functional requirements of a system ahead of the formal Analysis and Design process. So that just means more work up front for the Business Analyst or Functional Consultants right? Well no…..the design of a solution, particularly when it involves a complex custom extension, does not necessarily take longer just because you put more thought into the functional requirements. In fact, one could argue the complete opposite, in that by putting more emphasis on clearly understanding the nuances of functionality requirements early in the process, then the overall time and cost incurred during the Analysis to Design process should be less. In short, as your understanding of requirements matures over time, it is far easier (and more cost effective) to update a document or a diagram, than to change lines of code. So how does that translate into Tasks and Work Products in OUM? Let us assume you have reached a point on a project where a Custom Extension is needed. One of the first things you should consider doing is creating a Use Case, and remember, a Use Case could be as simple as a few lines of text reflecting a “User Story”, or it could be what Cockburn1 describes a “fully dressed Use Case”. It is worth mentioned at this point the highly scalable nature of OUM in the sense that “documents” should not be produced just because that is the way we have always done things. Some projects may well be predicated upon a base of electronic documents, whilst other projects may take a much more Agile approach to describing functional requirements; through “User Stories” perhaps. In any event, it is quite common for a Custom Extension to involve the creation of several “components”, i.e. some new screens, an interface, a report etc. Therefore several Use Cases might be required, which in turn can then be assembled into a Use Case Package. Once you have the Use Cases attributed to an appropriate (fit-for-purpose) level of detail, and assembled into a Package, you can now create an Analysis Model for the Package. An Analysis Model is conceptual in nature, and depending on the solution being developing, would involve the creation of one or more diagrams (i.e. Sequence Diagrams, Collaboration Diagrams etc.) which collectively describe the Data, Behavior and Use Interface requirements of the solution. If required, the various elements of the Analysis Model may be indexed via an Analysis Specification. For Custom Extension projects that follow a pure Object Orientated approach, then the Analysis Model will naturally support the development of the Design Model without any further artifacts. However, for projects that are transitioning to this approach, then the various elements of the Analysis Model may be represented within the Analysis Specification. If we now return to the original question of “Where’s my MD.050”. The full answer would be: Capture the functional requirements within a Use Case Group related Use Cases into a Package Create an Analysis Model for each Package Consider creating an Analysis Specification (AN.100) as a index to each Analysis Model artifact An alternative answer for a relatively simple Custom Extension would be: Capture the functional requirements within a Use Case Optionally, group related Use Cases into a Package Create an Analysis Specification (AN.100) for each package 1 Cockburn, A, 2000, Writing Effective Use Case, Addison-Wesley Professional; Edition 1

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  • Adventures in MVVM &ndash; ViewModel Location and Creation

    - by Brian Genisio's House Of Bilz
    More Adventures in MVVM In this post, I am going to explore how I prefer to attach ViewModels to my Views.  I have published the code to my ViewModelSupport project on CodePlex in case you'd like to see how it works along with some examples.  Some History My approach to View-First ViewModel creation has evolved over time.  I have constructed ViewModels in code-behind.  I have instantiated ViewModels in the resources sectoin of the view. I have used Prism to resolve ViewModels via Dependency Injection. I have created attached properties that use Dependency Injection containers underneath.  Of all these approaches, I continue to find issues either in composability, blendability or maintainability.  Laurent Bugnion came up with a pretty good approach in MVVM Light Toolkit with his ViewModelLocator, but as John Papa points out, it has maintenance issues.  John paired up with Glen Block to make the ViewModelLocator more generic by using MEF to compose ViewModels.  It is a great approach, but I don’t like baking in specific resolution technologies into the ViewModelSupport project. I bring these people up, not to name drop, but to give them credit for the place I finally landed in my journey to resolve ViewModels.  I have come up with my own version of the ViewModelLocator that is both generic and container agnostic.  The solution is blendable, configurable and simple to use.  Use any resolution mechanism you want: MEF, Unity, Ninject, Activator.Create, Lookup Tables, new, whatever. How to use the locator 1. Create a class to contain your resolution configuration: public class YourViewModelResolver: IViewModelResolver { private YourFavoriteContainer container = new YourFavoriteContainer(); public YourViewModelResolver() { // Configure your container } public object Resolve(string viewModelName) { return container.Resolve(viewModelName); } } Examples of doing this are on CodePlex for MEF, Unity and Activator.CreateInstance. 2. Create your ViewModelLocator with your custom resolver in App.xaml: <VMS:ViewModelLocator x:Key="ViewModelLocator"> <VMS:ViewModelLocator.Resolver> <local:YourViewModelResolver /> </VMS:ViewModelLocator.Resolver> </VMS:ViewModelLocator> 3. Hook up your data context whenever you want a ViewModel (WPF): <Border DataContext="{Binding YourViewModelName, Source={StaticResource ViewModelLocator}}"> This example uses dynamic properties on the ViewModelLocator and passes the name to your resolver to figure out how to compose it. 4. What about Silverlight? Good question.  You can't bind to dynamic properties in Silverlight 4 (crossing my fingers for Silverlight 5), but you CAN use string indexing: <Border DataContext="{Binding [YourViewModelName], Source={StaticResource ViewModelLocator}}"> But, as John Papa points out in his article, there is a silly bug in Silverlight 4 (as of this writing) that will call into the indexer 6 times when it binds.  While this is little more than a nuisance when getting most properties, it can be much more of an issue when you are resolving ViewModels six times.  If this gets in your way, the solution (as pointed out by John), is to use an IndexConverter (instantiated in App.xaml and also included in the project): <Border DataContext="{Binding Source={StaticResource ViewModelLocator}, Converter={StaticResource IndexConverter}, ConverterParameter=YourViewModelName}"> It is a bit uglier than the WPF version (this method will also work in WPF if you prefer), but it is still not all that bad.  Conclusion This approach works really well (I suppose I am a bit biased).  It allows for composability from any mechanisim you choose.  It is blendable (consider serving up different objects in Design Mode if you wish... or different constructors… whatever makes sense to you).  It works in Cider.  It is configurable.  It is flexible.  It is the best way I have found to manage View-First ViewModel hookups.  Thanks to the guys mentioned in this article for getting me to something I love using.  Enjoy.

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  • 5 Ways to Determine Mobile Location

    - by David Dorf
    In my previous post, I mentioned the importance of determining the location of a consumer using their mobile phone.  Retailers can track anonymous mobile phones to determine traffic patterns both inside and outside their stores.  And with consumers' permission, retailers can send location-aware offers to mobile phones; for example, a coupon for cereal as you walk down that aisle.  When paying with Square, your location is matched with the transaction.  So there are lots of reasons for retailers to want to know the location of their customers.  But how is it done? I thought I'd dive a little deeper on that topic and consider the approaches to determining location. 1. Tower Triangulation By comparing the relative signal strength from multiple antenna towers, a general location of a phone can be roughly determined to an accuracy of 200-1000 meters.  The more towers involved, the more accurate the location. 2. GPS Using Global Positioning Satellites is more accurate than using cell towers, but it takes longer to find the satellites, it uses more battery, and it won't well indoors.  For geo-fencing applications, like those provided by Placecast and Digby, cell towers are often used to determine if the consumer is nearing a "fence" then switches to GPS to determine the actual crossing of the fence. 3. WiFi Triangulation WiFi triangulation is usually more accurate than using towers just because there are so many more WiFi access points (i.e. radios in routers) around. The position of each WiFi AP needs to be recorded in a database and used in the calculations, which is what Skyhook has been doing since 2008.  Another advantage to this method is that works well indoors, although it usually requires additional WiFi beacons to get the accuracy down to 5-10 meters.  Companies like ZuluTime, Aisle411, and PointInside have been perfecting this approach for retailers like Meijer, Walgreens, and HomeDepot. Keep in mind that a mobile phone doesn't have to connect to the WiFi network in order for it to be located.  The WiFi radio in the phone only needs to be on.  Even when not connected, WiFi radios talk to each other to prepare for a possible connection. 4. Hybrid Approaches Naturally the most accurate approach is to combine the approaches described above.  The more available data points, the greater the accuracy.  Companies like ShopKick like to add in acoustic triangulation using the phone's microphone, and NearBuy can use video analytics to increase accuracy. 5. Magnetic Fields The latest approach, and this one is really new, takes a page from the animal kingdom.  As you've probably learned from guys like Marlin Perkins, some animals use the Earth's magnetic fields to navigate.  By recording magnetic variations within a store, then matching those readings with ones from a consumer's phone, location can be accurately determined.  At least that's the approach IndoorAtlas is taking, and the science seems to bear out.  It works well indoors, and doesn't require retailers to purchase any additional hardware.  Keep an eye on this one.

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  • Kill all the project files!

    - by jamiet
    Like many folks I’m a keen podcast listener and yesterday my commute was filled by listening to Scott Hunter being interviewed on .Net Rocks about the next version of ASP.Net. One thing Scott said really struck a chord with me. I don’t remember the full quote but he was talking about how the ASP.Net project file (i.e. the .csproj file) is going away. The rationale being that the main purpose of that file is to list all the other files in the project, and that’s something that the file system is pretty good at. In Scott’s own words (that someone helpfully put in the comments): A file that lists files is really redundant when the OS already does this Romeliz Valenciano correctly pointed out on Twitter that there will still be a project.json file however no longer will there be a need to keep a list of files in a project file. I suspect project.json will simply contain a list of exclusions where necessary rather than the current approach where the project file is a list of inclusions. On the face of it this seems like a pretty good idea. I’ve long been a fan of convention over configuration and this is a great example of that. Instead of listing all the files in a separate file, just treat all the files in the directory as being part of the project. Ostensibly the approach is if its in the directory, its part of the project. Simple. Now I’m not an ASP.net developer, far from it, but it did occur to me that the same approach could be applied to the two Visual Studio project types that I am most familiar with, SSIS & SSDT. Like many people I’ve long been irritated by SSIS projects that display a faux file system inside Solution Explorer. As you can see in the screenshot below the project has Miscellaneous and Connection Managers folders but no such folders exist on the file system: This may seem like a minor thing but it means useful Solution Explorer features like Show All Files and Open Folder in Windows Explorer don’t work and quite frankly it makes me feel like a second class citizen in the Microsoft ecosystem. I’m a developer, treat me like one. Don’t try and hide the detail of how a project works under the covers, show it to me. I’m a big boy, I can handle it! Would it not be preferable to simply treat all the .dtsx files in a directory as being part of a project? I think it would, that’s pretty much all the .dtproj file does anyway (that, and present things in a non-alphabetic order – something else that wildly irritates me), so why not just get rid of the .dtproj file? In the case of SSDT the .sqlproj actually does a whole lot more than simply list files because it also states the BuildAction of each file (Build, NotInBuild, Post-Deployment, etc…) but I see no reason why the convention over configuration approach can’t help us there either. Want to know which is the Post-deployment script? Well, its the one called Post-DeploymentScript.sql! Simple! So that’s my new crusade. Let’s kill all the project files (well, the .dtproj & .sqlproj ones anyway). Are you with me? @Jamiet

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  • When to use Aspect Oriented Architecture (AOA/AOD)

    When is it appropriate to use aspect oriented architecture? I think the only honest answer to this question is that it depends on the context for which the question is being asked. There really are no hard and fast rules regarding the selection of an architectural model(s) for a project because each model provides good and bad benefits. Every system is built with a unique requirements and constraints. This context will dictate when to use one type of architecture over another or in conjunction with others. To me aspect oriented architecture models should be a sub-phase in the architectural modeling and design process especially when creating enterprise level models. Personally, I like to use this approach to create a base architectural model that is defined by non-functional requirements and system quality attributes.   This general model can then be used as a starting point for additional models because it is targets all of the business key quality attributes required by the system.Aspect oriented architecture is a method for modeling non-functional requirements and quality attributes of a system known as aspects. These models do not deal directly with specific functionality. They do categorize functionality of the system. This approach allows a system to be created with a strong emphasis on separating system concerns into individual components. These cross cutting components enables a systems to create with compartmentalization in regards to non-functional requirements or quality attributes.  This allows for the reduction in code because an each component maintains an aspect of a system that can be called by other aspects. This approach also allows for a much cleaner and smaller code base during the implementation and support of a system. Additionally, enabling developers to develop systems based on aspect-oriented design projects will be completed faster and will be more reliable because existing components can be shared across a system; thus, the time needed to create and test the functionality is reduced.   Example of an effective use of Aspect Oriented ArchitectureIn my experiences, aspect oriented architecture can be very effective with large or more complex systems. Typically, these types of systems have a large number of concerns so the act of defining them is very beneficial for reducing the system’s complexity because components can be developed to address each concern while exposing functionality to the other system components. The benefits to using the aspect oriented approach as the starting point for a system is that it promotes communication between IT and the business due to the fact that the aspect oriented models are quality attributes focused so not much technical understanding is needed to understand the model.An example of this can be in developing a new intranet website. Common Intranet Concerns: Error Handling Security Logging Notifications Database connectivity Example of a not as effective use of Aspect Oriented ArchitectureAgain in my experiences, aspect oriented architecture is not as effective with small or less complex systems in comparison.  There is no need to model concerns for a system that has a limited amount of them because the added overhead would not be justified for the actual benefits of creating the aspect oriented architecture model.  Furthermore, these types of projects typically have a reduced time schedule and a limited budget.  The creation of the Aspect oriented models would increase the overhead of a project and thus increase the time needed to implement the system. An example of this is seen by creating a small application to poll a network share for new files and then FTP them to a new location.  The two primary concerns for this project is to monitor a network drive and FTP files to a new location.  There is no need to create an aspect model for this system because there will never be a need to share functionality amongst either of these concerns.  To add to my point, this system is so small that it could be created with just a few classes so the added layer of componentizing the concerns would be complete overkill for this situation. References:Brichau, Johan; D'Hondt, Theo. (2006) Aspect-Oriented Software Development (AOSD) - An Introduction. Retreived from: http://www.info.ucl.ac.be/~jbrichau/courses/introductionToAOSD.pdf

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  • Consumer Oriented Search In Oracle Endeca Information Discovery – Part 1

    - by Bob Zurek
    Information Discovery, a core capability of Oracle Endeca Information Discovery, enables business users to rapidly search, discover and navigate through a wide variety of big data including structured, unstructured and semi-structured data. One of the key capabilities, among many, that differentiate our solution from others in the Information Discovery market is our deep support for search across this growing amount of varied big data. Our method and approach is very different than classic simple keyword search that is found in may information discovery solutions. In this first part of a series on the topic of search, I will walk you through many of the key capabilities that go beyond the simple search box that you might experience in products where search was clearly an afterthought or attempt to catch up to our core capabilities in this area. Lets explore. The core data management solution of Oracle Endeca Information Discovery is the Endeca Server, a hybrid search-analytical database that his highly scalable and column-oriented in nature. We will talk in more technical detail about the capabilities of the Endeca Server in future blog posts as this post is intended to give you a feel for the deep search capabilities that are an integral part of the Endeca Server. The Endeca Server provides best-of-breed search features aw well as a new class of features that are the first to be designed around the requirement to bridge structured, semi-structured and unstructured big data. Some of the key features of search include type a heads, automatic alphanumeric spell corrections, positional search, Booleans, wildcarding, natural language, and category search and query classification dialogs. This is just a subset of the advanced search capabilities found in Oracle Endeca Information Discovery. Search is an important feature that makes it possible for business users to explore on the diverse data sets the Endeca Server can hold at any one time. The search capabilities in the Endeca server differ from other Information Discovery products with simple “search boxes” in the following ways: The Endeca Server Supports Exploratory Search.  Enterprise data frequently requires the user to explore content through an ad hoc dialog, with guidance that helps them succeed. This has implications for how to design search features. Traditional search doesn’t assume a dialog, and so it uses relevance ranking to get its best guess to the top of the results list. It calculates many relevance factors for each query, like word frequency, distance, and meaning, and then reduces those many factors to a single score based on a proprietary “black box” formula. But how can a business users, searching, act on the information that the document is say only 38.1% relevant? In contrast, exploratory search gives users the opportunity to clarify what is relevant to them through refinements and summaries. This approach has received consumer endorsement through popular ecommerce sites where guided navigation across a broad range of products has helped consumers better discover choices that meet their, sometimes undetermined requirements. This same model exists in Oracle Endeca Information Discovery. In fact, the Endeca Server powers many of the most popular e-commerce sites in the world. The Endeca Server Supports Cascading Relevance. Traditional approaches of search reduce many relevance weights to a single score. This means that if a result with a good title match gets a similar score to one with an exact phrase match, they’ll appear next to each other in a list. But a user can’t deduce from their score why each got it’s ranking, even though that information could be valuable. Oracle Endeca Information Discovery takes a different approach. The Endeca Server stratifies results by a primary relevance strategy, and then breaks ties within a strata by ordering them with a secondary strategy, and so on. Application managers get the explicit means to compose these strategies based on their knowledge of their own domain. This approach gives both business users and managers a deterministic way to set and understand relevance. Now that you have an understanding of two of the core search capabilities in Oracle Endeca Information Discovery, our next blog post on this topic will discuss more advanced features including set search, second-order relevance as well as an understanding of faceted search mechanisms that include queries and filters.  

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  • Bowing to User Experience

    As a consumer of geeky news it is hard to check my Google Reader without running into two or three posts about Apples iPad and in particular the changes to the developer guidelines which seemingly restrict developers to using Apples Xcode tool and Objective-C language for iPad apps. One of the alternatives to Objective-C affected, is MonoTouch, an option with some appeal to me as it is based on the Mono implementation of C#. Seemingly restricted is the key word here, as far as I can tell, no official announcement has been made about its fate. For more details around MonoTouch for iPhone OS, check out Miguel de Icazas post: http://tirania.org/blog/archive/2010/Apr-28.html. These restrictions have provoked some outrage as the perception is that Apple is arrogantly restricting developers freedom to create applications as they choose and perhaps unwittingly shortchanging iPhone/iPad users who wont benefit from these now never-to-be-made great applications. Apples response has mostly been to say they are concentrating on providing a certain user experience to their customers, and to do this, they insist everyone uses the tools they approve. Which isnt a surprising line of reasoning given Apple restricts the hardware used and content of the apps already. The vogue term for this approach is curated, as in a benevolent museum director selecting only the finest artifacts for display or a wise gardener arranging the plants in a garden just so. If this is what a curated experience is like it is hard to argue that consumers are not responding. My iPhone is probably the most satisfying piece of technology I own. Coming from the Razr, it really was an revolution in how the form factor, interface and user experience all tied together. While the curated approach reinvented the smart phone genre, it is easy to forget that this is not a new approach for Apple. Macbooks and Macs are Apple hardware that run Apple software. And theyve been successful, but not quite in the same way as the iPhone or iPad (based on early indications). Why not? Well a curated approach can only be wildly successful if the curator a) makes the right choices and b) offers choices that no one else has. Although its advantages are eroding, the iPhone was different from other phones, a unique, focused, touch-centric experience. The iPad is an attempt to define another category of computing. Macs and Macbooks are great devices, but are not fundamentally a different user experience than a PC, you still have windows, file folders, mouse and keyboard, and similar applications. So the big question for Apple is can they hold on to their market advantage, continuing innovating in user experience and stay on top? Or are they going be like Xerox, and the rest of the world says thank you for the windows metaphor, now let me implement that better? It will be exciting to watch, with Android already a viable competitor and Microsoft readying Windows Phone 7. And to close the loop back to the restrictions on developing for iPhone OS. At this point the main target appears to be Adobe and Adobe Flash. Apples calculation is that a) they dont need those developers or b) the developers they want will learn Apples stuff anyway. My guess is that they are correct; that as much as I like the idea of developers having more options, I am not going to buy a competitors product to spite Apple unless that product is just as usable. For a non-technical consumer, I dont know that this conversation even factors into the buying decision. If it did, wed be talking about how Microsoft is trying to retake a slice of market share from the behemoth that is Linux.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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