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  • Code Reuse is (Damn) Hard

    - by James Michael Hare
    Being a development team lead, the task of interviewing new candidates was part of my job.  Like any typical interview, we started with some easy questions to get them warmed up and help calm their nerves before hitting the hard stuff. One of those easier questions was almost always: “Name some benefits of object-oriented development.”  Nearly every time, the candidate would chime in with a plethora of canned answers which typically included: “it helps ease code reuse.”  Of course, this is a gross oversimplification.  Tools only ease reuse, its developers that ultimately can cause code to be reusable or not, regardless of the language or methodology. But it did get me thinking…  we always used to say that as part of our mantra as to why Object-Oriented Programming was so great.  With polymorphism, inheritance, encapsulation, etc. we in essence set up the concepts to help facilitate reuse as much as possible.  And yes, as a developer now of many years, I unquestionably held that belief for ages before it really struck me how my views on reuse have jaded over the years.  In fact, in many ways Agile rightly eschews reuse as taking a backseat to developing what's needed for the here and now.  It used to be I was in complete opposition to that view, but more and more I've come to see the logic in it.  Too many times I've seen developers (myself included) get lost in design paralysis trying to come up with the perfect abstraction that would stand all time.  Nearly without fail, all of these pieces of code become obsolete in a matter of months or years. It’s not that I don’t like reuse – it’s just that reuse is hard.  In fact, reuse is DAMN hard.  Many times it is just a distraction that eats up architect and developer time, and worse yet can be counter-productive and force wrong decisions.  Now don’t get me wrong, I love the idea of reusable code when it makes sense.  These are in the few cases where you are designing something that is inherently reusable.  The problem is, most business-class code is inherently unfit for reuse! Furthermore, the code that is reusable will often fail to be reused if you don’t have the proper framework in place for effective reuse that includes standardized versioning, building, releasing, and documenting the components.  That should always be standard across the board when promoting reusable code.  All of this is hard, and it should only be done when you have code that is truly reusable or you will be exerting a large amount of development effort for very little bang for your buck. But my goal here is not to get into how to reuse (that is a topic unto itself) but what should be reused.  First, let’s look at an extension method.  There’s many times where I want to kick off a thread to handle a task, then when I want to reign that thread in of course I want to do a Join on it.  But what if I only want to wait a limited amount of time and then Abort?  Well, I could of course write that logic out by hand each time, but it seemed like a great extension method: 1: public static class ThreadExtensions 2: { 3: public static bool JoinOrAbort(this Thread thread, TimeSpan timeToWait) 4: { 5: bool isJoined = false; 6:  7: if (thread != null) 8: { 9: isJoined = thread.Join(timeToWait); 10:  11: if (!isJoined) 12: { 13: thread.Abort(); 14: } 15: } 16: return isJoined; 17: } 18: } 19:  When I look at this code, I can immediately see things that jump out at me as reasons why this code is very reusable.  Some of them are standard OO principles, and some are kind-of home grown litmus tests: Single Responsibility Principle (SRP) – The only reason this extension method need change is if the Thread class itself changes (one responsibility). Stable Dependencies Principle (SDP) – This method only depends on classes that are more stable than it is (System.Threading.Thread), and in itself is very stable, hence other classes may safely depend on it. It is also not dependent on any business domain, and thus isn't subject to changes as the business itself changes. Open-Closed Principle (OCP) – This class is inherently closed to change. Small and Stable Problem Domain – This method only cares about System.Threading.Thread. All-or-None Usage – A user of a reusable class should want the functionality of that class, not parts of that functionality.  That’s not to say they most use every method, but they shouldn’t be using a method just to get half of its result. Cost of Reuse vs. Cost to Recreate – since this class is highly stable and minimally complex, we can offer it up for reuse very cheaply by promoting it as “ready-to-go” and already unit tested (important!) and available through a standard release cycle (very important!). Okay, all seems good there, now lets look at an entity and DAO.  I don’t know about you all, but there have been times I’ve been in organizations that get the grand idea that all DAOs and entities should be standardized and shared.  While this may work for small or static organizations, it’s near ludicrous for anything large or volatile. 1: namespace Shared.Entities 2: { 3: public class Account 4: { 5: public int Id { get; set; } 6:  7: public string Name { get; set; } 8:  9: public Address HomeAddress { get; set; } 10:  11: public int Age { get; set;} 12:  13: public DateTime LastUsed { get; set; } 14:  15: // etc, etc, etc... 16: } 17: } 18:  19: ... 20:  21: namespace Shared.DataAccess 22: { 23: public class AccountDao 24: { 25: public Account FindAccount(int id) 26: { 27: // dao logic to query and return account 28: } 29:  30: ... 31:  32: } 33: } Now to be fair, I’m not saying there doesn’t exist an organization where some entites may be extremely static and unchanging.  But at best such entities and DAOs will be problematic cases of reuse.  Let’s examine those same tests: Single Responsibility Principle (SRP) – The reasons to change for these classes will be strongly dependent on what the definition of the account is which can change over time and may have multiple influences depending on the number of systems an account can cover. Stable Dependencies Principle (SDP) – This method depends on the data model beneath itself which also is largely dependent on the business definition of an account which can be very inherently unstable. Open-Closed Principle (OCP) – This class is not really closed for modification.  Every time the account definition may change, you’d need to modify this class. Small and Stable Problem Domain – The definition of an account is inherently unstable and in fact may be very large.  What if you are designing a system that aggregates account information from several sources? All-or-None Usage – What if your view of the account encompasses data from 3 different sources but you only care about one of those sources or one piece of data?  Should you have to take the hit of looking up all the other data?  On the other hand, should you have ten different methods returning portions of data in chunks people tend to ask for?  Neither is really a great solution. Cost of Reuse vs. Cost to Recreate – DAOs are really trivial to rewrite, and unless your definition of an account is EXTREMELY stable, the cost to promote, support, and release a reusable account entity and DAO are usually far higher than the cost to recreate as needed. It’s no accident that my case for reuse was a utility class and my case for non-reuse was an entity/DAO.  In general, the smaller and more stable an abstraction is, the higher its level of reuse.  When I became the lead of the Shared Components Committee at my workplace, one of the original goals we looked at satisfying was to find (or create), version, release, and promote a shared library of common utility classes, frameworks, and data access objects.  Now, of course, many of you will point to nHibernate and Entity for the latter, but we were looking at larger, macro collections of data that span multiple data sources of varying types (databases, web services, etc). As we got deeper and deeper in the details of how to manage and release these items, it quickly became apparent that while the case for reuse was typically a slam dunk for utilities and frameworks, the data access objects just didn’t “smell” right.  We ended up having session after session of design meetings to try and find the right way to share these data access components. When someone asked me why it was taking so long to iron out the shared entities, my response was quite simple, “Reuse is hard...”  And that’s when I realized, that while reuse is an awesome goal and we should strive to make code maintainable, often times you end up creating far more work for yourself than necessary by trying to force code to be reusable that inherently isn’t. Think about classes the times you’ve worked in a company where in the design session people fight over the best way to implement a class to make it maximally reusable, extensible, and any other buzzwordable.  Then think about how quickly that design became obsolete.  Many times I set out to do a project and think, “yes, this is the best design, I can extend it easily!” only to find out the business requirements change COMPLETELY in such a way that the design is rendered invalid.  Code, in general, tends to rust and age over time.  As such, writing reusable code can often be difficult and many times ends up being a futile exercise and worse yet, sometimes makes the code harder to maintain because it obfuscates the design in the name of extensibility or reusability. So what do I think are reusable components? Generic Utility classes – these tend to be small classes that assist in a task and have no business context whatsoever. Implementation Abstraction Frameworks – home-grown frameworks that try to isolate changes to third party products you may be depending on (like writing a messaging abstraction layer for publishing/subscribing that is independent of whether you use JMS, MSMQ, etc). Simplification and Uniformity Frameworks – To some extent this is similar to an abstraction framework, but there may be one chosen provider but a development shop mandate to perform certain complex items in a certain way.  Or, perhaps to simplify and dumb-down a complex task for the average developer (such as implementing a particular development-shop’s method of encryption). And what are less reusable? Application and Business Layers – tend to fluctuate a lot as requirements change and new features are added, so tend to be an unstable dependency.  May be reused across applications but also very volatile. Entities and Data Access Layers – these tend to be tuned to the scope of the application, so reusing them can be hard unless the abstract is very stable. So what’s the big lesson?  Reuse is hard.  In fact it’s damn hard.  And much of the time I’m not convinced we should focus too hard on it. If you’re designing a utility or framework, then by all means design it for reuse.  But you most also really set down a good versioning, release, and documentation process to maximize your chances.  For anything else, design it to be maintainable and extendable, but don’t waste the effort on reusability for something that most likely will be obsolete in a year or two anyway.

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  • Oracle redonne un élan au Projet Lambda sur Java 7 et les closures : Interface evolution via "public

    Bonjour, Depuis quelques temps, on n'entendait plus trop parler des Closures et de leur ajout à Java 7. En réponse à David Flanagan qui s'inquiétait récemment du silence d'Oracle et de la stagnation du Project Lambda, Brian Goetz (Oracle) a soumis il y a quelques jours un document de réflexion sur la notion de virtual extension methods permettant d'ajouter sur une interface existante de nouvelles méthodes (avec des implémentations par défaut) sans casser le contrat avec le code existant.

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  • Building Publishing Pages in Code

    - by David Jacobus
    Originally posted on: http://geekswithblogs.net/djacobus/archive/2013/10/27/154478.aspxOne of the Mantras we developers try to follow: Ensure that the solution package we deliver to the client is complete.  We build Web Parts, Master Pages, Images, CSS files and other artifacts that we push to the client with a WSP (Solution Package) And then we have them finish the solution by building their site pages by adding the web parts to the site pages.       I am a proponent that we,  the developers,  should minimize this time consuming work and build these site pages in code.  I found a few blogs and some MSDN documentation but not really a complete solution that has all these artifacts working in one solution.   What I am will discuss and provide a solution for is a package that has: 1.  Master Page 2.  Page Layout 3.  Page Web Parts 4.  Site Pages   Most all done in code without the development team or the developers having to finish up the site building process spending a few hours or days completing the site!  I am not implying that in Development we do this. In fact,  we build these pages incrementally testing our web parts, etc. I am saying that the final action in our solution is that we take all these artifacts and add them to the site pages in code, the client then only needs to activate a few features and VIOLA their site appears!.  I had a project that had me build 8 pages like this as part of the solution.   In this blog post, I am taking a master page solution that I have called DJGreenMaster.  On My Office 365 Development Site it looks like this:     It is a generic master page for a SharePoint 2010 site Along with a three column layout.  Centered with a footer that uses a SharePoint List and Web Part for the footer links.  I use this master page a lot in my site development!  Easy to change the color and site logo with a little CSS.   I am going to add a few web parts for discussion purposes and then add these web parts to a site page in code.    Lets look at the solution package for DJ Green Master as that will be the basis project for building the site pages:   What you are seeing  is a complete solution to add a Master Page to a site collection which contains: 1.  Master Page Module which contains the Master Page and Page Layout 2.  The Footer Module to add the Footer Web Part 3.  Miscellaneous modules to add images, JQuery, CSS and subsite page 4.  3 features and two feature event receivers: a.  DJGreenCSS, used to add the master page CSS file to Style Sheet Library and an Event Receiver to check it in. b.  DJGreenMaster used to add the Master Page and Page Layout.  In an Event Receiver change the master page to DJGreenMaster , create the footer list and check the files in. c.  DJGreenMasterWebParts add the Footer Web Part to the site collection. I won’t go over the code for this as I will give it to you at the end of this blog post. I have discussed creating a list in code in a previous post.  So what we have is the basis to begin what is germane to this discussion.  I have the first two requirements completed.  I need now to add page web parts and the build the pages in code.  For the page web parts, I will use one downloaded from Codeplex which does not use a SharePoint custom list for simplicity:   Weather Web Part and another downloaded from MSDN which is a SharePoint Custom Calendar Web Part, I had to add some functionality to make the events color coded to exceed the built-in 10 overlays using JQuery!    Here is the solution with the added projects:     Here is a screen shot of the Weather Web Part Deployed:   Here is a screen shot of the Site Calendar with JQuery:     Okay, Now we get to the final item:  To create Publishing pages.   We need to add a feature receiver to the DJGreenMaster project I will name it DJSitePages and also add a Event Receiver:       We will build the page at the site collection level and all of the code necessary will be contained in the event receiver.   Added a reference to the Microsoft.SharePoint.Publishing.dll contained in the ISAPI folder of the 14 Hive.   First we will add some static methods from which we will call  in our Event Receiver:   1: private static void checkOut(string pagename, PublishingPage p) 2: { 3: if (p.Name.Equals(pagename, StringComparison.InvariantCultureIgnoreCase)) 4: { 5: 6: if (p.ListItem.File.CheckOutType == SPFile.SPCheckOutType.None) 7: { 8: p.CheckOut(); 9: } 10:   11: if (p.ListItem.File.CheckOutType == SPFile.SPCheckOutType.Online) 12: { 13: p.CheckIn("initial"); 14: p.CheckOut(); 15: } 16: } 17: } 18: private static void checkin(PublishingPage p,PublishingWeb pw) 19: { 20: SPFile publishFile = p.ListItem.File; 21:   22: if (publishFile.CheckOutType != SPFile.SPCheckOutType.None) 23: { 24:   25: publishFile.CheckIn( 26:   27: "CheckedIn"); 28:   29: publishFile.Publish( 30:   31: "published"); 32: } 33: // In case of content approval, approve the file need to add 34: //pulishing site 35: if (pw.PagesList.EnableModeration) 36: { 37: publishFile.Approve("Initial"); 38: } 39: publishFile.Update(); 40: }   In a Publishing Site, CheckIn and CheckOut  are required when dealing with pages in a publishing site.  Okay lets look at the Feature Activated Event Receiver: 1: public override void FeatureActivated(SPFeatureReceiverProperties properties) 2: { 3:   4:   5:   6: object oParent = properties.Feature.Parent; 7:   8:   9:   10: if (properties.Feature.Parent is SPWeb) 11: { 12:   13: currentWeb = (SPWeb)oParent; 14:   15: currentSite = currentWeb.Site; 16:   17: } 18:   19: else 20: { 21:   22: currentSite = (SPSite)oParent; 23:   24: currentWeb = currentSite.RootWeb; 25:   26: } 27: 28:   29: //create the publishing pages 30: CreatePublishingPage(currentWeb, "Home.aspx", "ThreeColumnLayout.aspx","Home"); 31: //CreatePublishingPage(currentWeb, "Dummy.aspx", "ThreeColumnLayout.aspx","Dummy"); 32: }     Basically we are calling the method Create Publishing Page with parameters:  Current Web, Name of the Page, The Page Layout, Title of the page.  Let’s look at the Create Publishing Page method:   1:   2: private void CreatePublishingPage(SPWeb site, string pageName, string pageLayoutName, string title) 3: { 4: PublishingSite pubSiteCollection = new PublishingSite(site.Site); 5: PublishingWeb pubSite = null; 6: if (pubSiteCollection != null) 7: { 8: // Assign an object to the pubSite variable 9: if (PublishingWeb.IsPublishingWeb(site)) 10: { 11: pubSite = PublishingWeb.GetPublishingWeb(site); 12: } 13: } 14: // Search for the page layout for creating the new page 15: PageLayout currentPageLayout = FindPageLayout(pubSiteCollection, pageLayoutName); 16: // Check or the Page Layout could be found in the collection 17: // if not (== null, return because the page has to be based on 18: // an excisting Page Layout 19: if (currentPageLayout == null) 20: { 21: return; 22: } 23:   24: 25: PublishingPageCollection pages = pubSite.GetPublishingPages(); 26: foreach (PublishingPage p in pages) 27: { 28: //The page allready exists 29: if ((p.Name == pageName)) return; 30:   31: } 32: 33:   34:   35: PublishingPage newPage = pages.Add(pageName, currentPageLayout); 36: newPage.Description = pageName.Replace(".aspx", ""); 37: // Here you can set some properties like: 38: newPage.IncludeInCurrentNavigation = true; 39: newPage.IncludeInGlobalNavigation = true; 40: newPage.Title = title; 41: 42: 43:   44:   45: 46:   47: //build the page 48:   49: 50: switch (pageName) 51: { 52: case "Homer.aspx": 53: checkOut("Courier.aspx", newPage); 54: BuildHomePage(site, newPage); 55: break; 56:   57:   58: default: 59: break; 60: } 61: // newPage.Update(); 62: //Now we can checkin the newly created page to the “pages” library 63: checkin(newPage, pubSite); 64: 65: 66: }     The narrative in what is going on here is: 1.  We need to find out if we are dealing with a Publishing Web.  2.  Get the Page Layout 3.  Create the Page in the pages list. 4.  Based on the page name we build that page.  (Here is where we can add all the methods to build multiple pages.) In the switch we call Build Home Page where all the work is done to add the web parts.  Prior to adding the web parts we need to add references to the two web part projects in the solution. using WeatherWebPart.WeatherWebPart; using CSSharePointCustomCalendar.CustomCalendarWebPart;   We can then reference them in the Build Home Page method.   Let’s look at Build Home Page: 1:   2: private static void BuildHomePage(SPWeb web, PublishingPage pubPage) 3: { 4: // build the pages 5: // Get the web part manager for each page and do the same code as below (copy and paste, change to the web parts for the page) 6: // Part Description 7: SPLimitedWebPartManager mgr = web.GetLimitedWebPartManager(web.Url + "/Pages/Home.aspx", System.Web.UI.WebControls.WebParts.PersonalizationScope.Shared); 8: WeatherWebPart.WeatherWebPart.WeatherWebPart wwp = new WeatherWebPart.WeatherWebPart.WeatherWebPart() { ChromeType = PartChromeType.None, Title = "Todays Weather", AreaCode = "2504627" }; 9: //Dictionary<string, string> wwpDic= new Dictionary<string, string>(); 10: //wwpDic.Add("AreaCode", "2504627"); 11: //setWebPartProperties(wwp, "WeatherWebPart", wwpDic); 12:   13: // Add the web part to a pagelayout Web Part Zone 14: mgr.AddWebPart(wwp, "g_685594D193AA4BBFABEF2FB0C8A6C1DD", 1); 15:   16: CSSharePointCustomCalendar.CustomCalendarWebPart.CustomCalendarWebPart cwp = new CustomCalendarWebPart() { ChromeType = PartChromeType.None, Title = "Corporate Calendar", listName="CorporateCalendar" }; 17:   18: mgr.AddWebPart(cwp, "g_20CBAA1DF45949CDA5D351350462E4C6", 1); 19:   20:   21: pubPage.Update(); 22:   23: } Here is what we are doing: 1.  We got  a reference to the SharePoint Limited Web Part Manager and linked/referenced Home.aspx  2.  Instantiated the a new Weather Web Part and used the Manager to add it to the page in a web part zone identified by ID,  thus the need for a Page Layout where the developer knows the ID’s. 3.  Instantiated the Calendar Web Part and used the Manager to add it to the page. 4. We the called the Publishing Page update method. 5.  Lastly, the Create Publishing Page method checks in the page just created.   Here is a screen shot of the page right after a deploy!       Okay!  I know we could make a home page look much better!  However, I built this whole Integrated solution in less than a day with the caveat that the Green Master was already built!  So what am I saying?  Build you web parts, master pages, etc.  At the very end of the engagement build the pages.  The client will be very happy!  Here is the code for this solution Code

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  • throw new exception- C#

    - by Jalpesh P. Vadgama
    This post will be in response to my older post throw vs. throw(ex) best practice and difference- c# comment that I should include throw new exception. What’s wrong with throw new exception: Throw new exception is even worse, It will create a new exception and will erase all the earlier exception data. So it will erase stack trace also.Please go through following code. It’s same earlier post the only difference is throw new exception.   using System; namespace Oops { class Program { static void Main(string[] args) { try { DevideByZero(10); } catch (Exception exception) { throw new Exception (string.Format( "Brand new Exception-Old Message:{0}", exception.Message)); } } public static void DevideByZero(int i) { int j = 0; int k = i/j; Console.WriteLine(k); } } } Now once you run this example. You will get following output as expected. Hope you like it. Stay tuned for more..

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  • Which web framework to use under Backbonejs?

    - by egidra
    For a previous project, I was using Backbonejs alongside Django, but I found out that I didn't use many features from Django. So, I am looking for a lighter framework to use underneath a Backbonejs web app. I never used Django built in templates. When I did, it was to set up the initial index page, but that's all. I did use the user management system that Django provided. I used the models.py, but never views.py. I used urls.py to set up which template the user would hit upon visiting the site. I noticed that the two features that I used most from Django was South and Tastypie, and they aren't even included with Django. Particularly, django-tastypie made it easy for me to link up my frontend models to my backend models. It made it easy to JSONify my front end models and send them to Tastypie. Although, I found myself overriding a lot of tastypie's methods for GET, PUT, POST requests, so it became useless. South made it easy to migrate new changes to the database. Although, I had so much trouble with South. Is there a framework with an easier way of handling database modifications than using South? When using South with multiple people, we had the worse time keeping our databases synced. When someone added a new table and pushed their migration to git, the other two people would spend days trying to use South's automatic migration, but it never worked. I liked how Rails had a manual way of migrating databases. Even though I used Tastypie and South a lot, I found myself not actually liking them because I ended up overriding most Tastypie methods for each Resource, and I also had the worst trouble migrating new tables and columns with South. So, I would like a framework that makes that process easier. Part of my problem was that they are too "magical". Which framework should I use? Nodejs or a lighter Python framework? Which works best with my above criteria?

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  • Need help making site available externally

    - by White Island
    I'm trying to open a hole in the firewall (ASA 5505, v8.2) to allow external access to a Web application. Via ASDM (6.3?), I've added the server as a Public Server, which creates a static NAT entry [I'm using the public IP that is assigned to 'dynamic NAT--outgoing' for the LAN, after confirming on the Cisco forums that it wouldn't bring everyone's access crashing down] and an incoming rule "any... public_ip... https... allow" but traffic is still not getting through. When I look at the log viewer, it says it's denied by access-group outside_access_in, implicit rule, which is "any any ip deny" I haven't had much experience with Cisco management. I can't see what I'm missing to allow this connection through, and I'm wondering if there's anything else special I have to add. I tried adding a rule (several variations) within that access-group to allow https to the server, but it never made a difference. Maybe I haven't found the right combination? :P I also made sure the Windows firewall is open on port 443, although I'm pretty sure the current problem is Cisco, because of the logs. :) Any ideas? If you need more information, please let me know. Thanks Edit: First of all, I had this backward. (Sorry) Traffic is being blocked by access-group "inside_access_out" which is what confused me in the first place. I guess I confused myself again in the midst of typing the question. Here, I believe, is the pertinent information. Please let me know what you see wrong. access-list acl_in extended permit tcp any host PUBLIC_IP eq https access-list acl_in extended permit icmp CS_WAN_IPs 255.255.255.240 any access-list acl_in remark Allow Vendor connections to LAN access-list acl_in extended permit tcp host Vendor any object-group RemoteDesktop access-list acl_in remark NetworkScanner scan-to-email incoming (from smtp.mail.microsoftonline.com to PCs) access-list acl_in extended permit object-group TCPUDP any object-group Scan-to-email host NetworkScanner object-group Scan-to-email access-list acl_out extended permit icmp any any access-list acl_out extended permit tcp any any access-list acl_out extended permit udp any any access-list SSLVPNSplitTunnel standard permit LAN_Subnet 255.255.255.0 access-list nonat extended permit ip VPN_Subnet 255.255.255.0 LAN_Subnet 255.255.255.0 access-list nonat extended permit ip LAN_Subnet 255.255.255.0 VPN_Subnet 255.255.255.0 access-list inside_access_out remark NetworkScanner Scan-to-email outgoing (from scanner to Internet) access-list inside_access_out extended permit object-group TCPUDP host NetworkScanner object-group Scan-to-email any object-group Scan-to-email access-list inside_access_out extended permit tcp any interface outside eq https static (inside,outside) PUBLIC_IP LOCAL_IP[server object] netmask 255.255.255.255 I wasn't sure if I needed to reverse that "static" entry, since I got my question mixed up... and also with that last access-list entry, I tried interface inside and outside - neither proved successful... and I wasn't sure about whether it should be www, since the site is running on https. I assumed it should only be https.

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  • Is there a clean separation of my layers with this attempt at Domain Driven Design in XAML and C#

    - by Buddy James
    I'm working on an application. I'm using a mixture of TDD and DDD. I'm working hard to separate the layers of my application and that is where my question comes in. My solution is laid out as follows Solution MyApp.Domain (WinRT class library) Entity (Folder) Interfaces(Folder) IPost.cs (Interface) BlogPosts.cs(Implementation of IPost) Service (Folder) Interfaces(Folder) IDataService.cs (Interface) BlogDataService.cs (Implementation of IDataService) MyApp.Presentation(Windows 8 XAML + C# application) ViewModels(Folder) BlogViewModel.cs App.xaml MainPage.xaml (Contains a property of BlogViewModel MyApp.Tests (WinRT Unit testing project used for my TDD) So I'm planning to use my ViewModel with the XAML UI I'm writing a test and define my interfaces in my system and I have the following code thus far. [TestMethod] public void Get_Zero_Blog_Posts_From_Presentation_Layer_Returns_Empty_Collection() { IBlogViewModel viewModel = _container.Resolve<IBlogViewModel>(); viewModel.LoadBlogPosts(0); Assert.AreEqual(0, viewModel.BlogPosts.Count, "There should be 0 blog posts."); } viewModel.BlogPosts is an ObservableCollection<IPost> Now.. my first thought is that I'd like the LoadBlogPosts method on the ViewModel to call a static method on the BlogPost entity. My problem is I feel like I need to inject the IDataService into the Entity object so that it promotes loose coupling. Here are the two options that I'm struggling with: Not use a static method and use a member method on the BlogPost entity. Have the BlogPost take an IDataService in the constructor and use dependency injection to resolve the BlogPost instance and the IDataService implementation. Don't use the entity to call the IDataService. Put the IDataService in the constructor of the ViewModel and use my container to resolve the IDataService when the viewmodel is instantiated. So with option one the layers will look like this ViewModel(Presentation layer) - Entity (Domain layer) - IDataService (Service Layer) or ViewModel(Presentation layer) - IDataService (Service Layer)

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  • Using Article Sites For SEO Google Ranking

    Article marketing is one of the highly awarding methods for online marketing and it can also help you achieve good SEO Google Ranking. With the various article directories you can get a good amount of marketing done however with a little more focus and attention you will be able to use all features that are offered by these directories.

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  • Revision Methodology for Developer Post as Entry Level

    - by Demla Pawan
    I had revised all basic concepts of my computer science ciriculum like: Core Java(basics),SQL(basics),C++(basics),XHTML,PHP(basics),Datastructures(basics) and what I need to do,and How to do, as their may be fault in my preparation methods for revision session's, So can Anybody suggest Methodology to revise those technical things,to which you are not in touch at present, but you can write basic programs or have used 1-2 years ago. And also can U suggest some Quick revision links on Net for various technologies mentioned above.

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  • How do you exclude yourself from Google Analytics on your website using cookies?

    - by Keoki Zee
    I'm trying to set up an exclusion filter with a browser cookie, so that my own visits to my don't show up in my Google Analytics. I tried 3 different methods and none of them have worked so far. I would like help understanding what I am doing wrong and how I can fix this. Method 1 First, I tried following Google's instructions, http://www.google.com/support/analytics/bin/answer.py?hl=en&answer=55481, for excluding traffic by Cookie Content: Create a new page on your domain, containing the following code: <body onLoad="javascript:pageTracker._setVar('test_value');"> Method 2 Next, when that didn't work, I googled around and found this Google thread, http://www.google.com/support/forum/p/Google%20Analytics/thread?tid=4741f1499823fcd5&hl=en, where the most popular answer says to use a slightly different code: SHS Analytics wrote: <body onLoad="javascript:_gaq.push(['_setVar','test_value']);"> Thank you! This has now set a __utmv cookie containing "test_value", whereas the original: pageTracker._setVar('test_value') (which Google is still recommending) did not manage to do that for me (in Mac Safari 5 and Firefox 3.6.8). So I tried this code, but it didn't work for me. Method 3 Finally, I searched StackOverflow and came across this thread, http://stackoverflow.com/questions/3495270/exclude-my-traffic-from-google-analytics-using-cookie-with-subdomain, which suggests that the following code might work: <script type="text/javascript"> var _gaq = _gaq || []; _gaq.push(['_setVar', 'exclude_me']); _gaq.push(['_setAccount', 'UA-xxxxxxxx-x']); _gaq.push(['_trackPageview']); // etc... </script> This script appeared in the head element in the example, instead of in the onload event of the body like in the previous 2 examples. So I tried this too, but still had no luck with trying to exclude myself from Google Analytics. Re-iterate question So, I tried all 3 methods above with no success. Am I doing something wrong? How can I exclude myself from my Google Analytics using an exclusion cookie for my browser?

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  • Ubuntu web site hosting & free ,tk domain

    - by user5819
    Hello, I am sort of new to web hosting so sorry if I ask bad questions. I have a pc that runs ubuntu I instaled apache and now I host a web site, but I need a domain name so I found out .tk is free. The site works when typing 192.168.1.x in the browser(x= a number) but in dot.tk when I register in ip it whats one that look like 79.117.x.x so thats where I get stuck, I think I managed to make my ip address static but it still looks like 192.168.1.x and I can't put that in because it says: " This IP address is not valid". Why must it have the ip address that looks like 79.117.x.x and won't work with the internal static one and how can I do to host my site with a .tk domain name ? PS: I'm using a cisco router that's connected with computer via a cable.

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  • The Best Way to Build Backlinks - A List of 36 Sites to Get Backlinks

    Every webmaster can understand the meaning of backlinks. We need backlinks to rank our sites higher in Google and other search engines. Search engines count the number of backlinks for a web page and assign a rank to it in in search results. Hence, every webmaster always look to get as many backlinks as possible. In this article I explained few free methods of getting links.

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  • 7 Tips For Strong On Page SEO

    On page SEO is the first thing a webmaster should consider when planning the marketing of his website. Follow these simple yet effective methods to give your SEO campaign a kick start.

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  • Dominating Search Results With Local SEO

    Local Businesses are turning to local SEO services to obtain high placement with the major search engines. With tens of millions of websites currently online, dominant placement with the search engines is vital for online success. To obtain high placement within search engine results, you will need to deploy proven search engine optimization methods.

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  • links for 2011-01-07

    - by Bob Rhubart
    Enterprise Software Development with Java: GlassFish 3 vs. JBoss 6 - Is the Web Profile ready for the Enterprise? (tags: ping.fm) Bay Area Coherence Special Interest Group (BACSIG) Jan 20 The Jan 20 meeting of the Bay Area Coherence Special Interest Group (BACSIG) features presentations by Rob Lee (Coherence 3.6 Clustering Features), Rao Bhethanabotla (Efficient Management and Update of Coherence Clusters to Reduce Down Time), and Christer Fahlgren (How To Build a Coherence Practice). (tags: oracle otn coherence sig) Michael T. Dinh: VirtualBox Command Line "I have manually configured VirtualBox Host-Only Ethernet Adapter for static IP. However, the IP can change after reboot which affects connectivity with the Guest with static IP." - Michael T. Dinh (tags: oracle virtualization virtualbox) Michel Schildmeijer: Oracle WebLogic - Configuring DyeInjection Monitor "A fairly unknown tool within WLDF (WebLogic Diagnostic Framework) is the DyeInjection Monitor. With this monitor configured one can track a  user or client address within a WebLogic system." - Michel Schildmeijer (tags: oracle weblogic) David Butler: Master Data Management Implementation Styles "Oracle MDM Solutions provide strong data federation and integration capabilities which are key to enabling the use of the Confederated Hub as a possible architectural style approach." - David Butler (tags: oracle otn softwarearchitecture) Kenneth Downs: Can You Really Create A Business Logic Layer? "Don't be afraid to use the database for what it is good for, and leave the arguments about "where everything belongs" to those with too much time on their hands." - Kenneth Downs (tags: businesslogic database softwarearchitecture) IASA Perspectives Magazine - Fall 2010 Fall 2010 edition of International Association of Software Architects (IASA) Perspectives magazine: (tags: softwarearchitecture iasi entarch) Using the DB Adapter in Oracle SOA Suite: returning status information "In this tutorial I will show you an example of how how can implement this within the Oracle SOA Suite (and because the DB Adapter can also be used within the Oracle Service Bus, the principles also apply to implementing it within the OSB)." - Henk Jan van Wijk (tags: oracle otn soa soasuite database) 4th International SOA Symposium + 3rd International Cloud Symposium by Thomas Erl - call for presentations (SOA Partner Community Blog) The International SOA and Cloud Symposium brings together lessons learned and emerging topics from SOA and Cloud projects, practitioners and experts. The two-day conference agenda will be organized into several tracks. (tags: oracle otn soa cloud)

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  • Returning null vs Throwing exceptions

    - by Svish
    Is in a bit of disagreement with a more experienced developer on this issue, and was wondering what you guys here think about this. Environment is Java, EJB 3, services, etc. The code I wrote calls a service to get things and to create things. Problem was that I got null pointer exceptions in places that didn't make sense. For example when I asked the service to create an object, I got null back. And when I tried to look up an object with an id I knew existed, I still got null back. Was like it was ignoring me. Spent some time trying to figure out what was wrong in my code (since I'm less experienced I usually assume I have messed up). Turns out the reason was security. If the user principal using my service didn't have the right permissions to use the service I called from my service, then that service simply returned null. The services that are here already are usually not documented either, so this is just something you have to know... somehow... So here is the thing: I mean that this is rather confusing as a developer interacting with this service. To me it would make much more sense if that service thew an exception which would tell me that hey, you don't have the proper permissions to get info about this thing or to create this new thing. I would then immediately know why my service wasn't working as expected. However, he argued that asking is not wrong. Exceptions should only be thrown when there is an error and asking for a thing is not an error. Even if you don't have permission to "see" that the thing you asked for. The things are often looked up in a GUI by users and for those users not having the right permissions, these things simply "do not exist". So, in short: Asking is not wrong, hence no exception. Get methods return null because to those users those things "doesn't exist". Create methods return null because nothing was created, since the user wasn't allowed to create anything. So, what do you guys think? Is this normal and/or good practice? I prefer exceptions as I prefer throwing and catching exceptions because I find it much easier to know what's going on. So I would for example also prefer to throw a NotFoundException if you asked for an id which didn't exist, rather than returning null. Anyways, just curious to what others think about this as I'm not the most experienced developer yet.

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  • Retrieve the full ASP.NET Form Buffer as a String

    - by Rick Strahl
    Did it again today: For logging purposes I needed to capture the full Request.Form data as a string and while it’s pretty easy to retrieve the buffer it always takes me a few minutes to remember how to do it. So I finally wrote a small helper function to accomplish this since this comes up rather frequently especially in debugging scenarios or in the immediate window. Here’s the quick function to get the form buffer as string: /// <summary> /// Returns the content of the POST buffer as string /// </summary> /// <returns></returns> public static string FormBufferToString() { HttpRequest Request = HttpContext.Current.Request; if (Request.TotalBytes > 0) return Encoding.Default.GetString(Request.BinaryRead(Request.TotalBytes)); return string.Empty; } Clearly a simple task, but handy to have in your library for reuse. You probably don’t want to call this if you have a massive inbound form buffer, or if the data you’re retrieving is binary. It’s probably a good idea to check the inbound content type before calling this function with something like this: var formBuffer = string.Empty; if (Request.ContentType.StartsWith("text/") || Request.ContentType == "application/x-www-form-urlencoded") ) { formBuffer = FormBufferToString(); } to ensure you’re working only on content types you can actually view as text. Now if I can only remember the name of this function in my library – it’s part of the static WebUtils class in the West Wind Web Toolkit if you want to check out a number of other useful Web helper functions.© Rick Strahl, West Wind Technologies, 2005-2011Posted in ASP.NET  

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  • How can I screen clients that try to register multiple times?

    - by Aba Dov
    My company offers a bonus to every client that register. We would like to prevent people from abusing this by registering several times. we thought about filtering clients by ip (there is a problem with workplaces where all stations have the same ip) cookies (if cookies are not allowed we might lose a client) I would like your opinions on these two methods and will be glad to hear about new ones. thanks

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  • Restricting joystick within a radius of center

    - by Phil
    I'm using Unity3d iOs and am using the example joysticks that came with one of the packages. It works fine but the area the joystick moves in is a rectangle which is unintuitive for my type of game. I can figure out how to see if the distance between the center and the current point is too far but I can't figure out how to constrain it to a certain distance without interrupting the finger tracking. Here's the relevant code: using UnityEngine; using System.Collections; public class Boundary { public Vector2 min = Vector2.zero; public Vector2 max = Vector2.zero; } public class Joystick : MonoBehaviour{ static private Joystick[] joysticks; // A static collection of all joysticks static private bool enumeratedJoysticks=false; static private float tapTimeDelta = 0.3f; // Time allowed between taps public bool touchPad; // Is this a TouchPad? public Rect touchZone; public Vector2 deadZone = Vector2.zero; // Control when position is output public bool normalize = false; // Normalize output after the dead-zone? public Vector2 position; // [-1, 1] in x,y public int tapCount; // Current tap count private int lastFingerId = -1; // Finger last used for this joystick private float tapTimeWindow; // How much time there is left for a tap to occur private Vector2 fingerDownPos; private float fingerDownTime; private float firstDeltaTime = 0.5f; private GUITexture gui; // Joystick graphic private Rect defaultRect; // Default position / extents of the joystick graphic private Boundary guiBoundary = new Boundary(); // Boundary for joystick graphic public Vector2 guiTouchOffset; // Offset to apply to touch input private Vector2 guiCenter; // Center of joystick private Vector3 tmpv3; private Rect tmprect; private Color tmpclr; public float allowedDistance; public enum JoystickType { movement, rotation } public JoystickType joystickType; public void Start() { // Cache this component at startup instead of looking up every frame gui = (GUITexture) GetComponent( typeof(GUITexture) ); // Store the default rect for the gui, so we can snap back to it defaultRect = gui.pixelInset; if ( touchPad ) { // If a texture has been assigned, then use the rect ferom the gui as our touchZone if ( gui.texture ) touchZone = gui.pixelInset; } else { // This is an offset for touch input to match with the top left // corner of the GUI guiTouchOffset.x = defaultRect.width * 0.5f; guiTouchOffset.y = defaultRect.height * 0.5f; // Cache the center of the GUI, since it doesn't change guiCenter.x = defaultRect.x + guiTouchOffset.x; guiCenter.y = defaultRect.y + guiTouchOffset.y; // Let's build the GUI boundary, so we can clamp joystick movement guiBoundary.min.x = defaultRect.x - guiTouchOffset.x; guiBoundary.max.x = defaultRect.x + guiTouchOffset.x; guiBoundary.min.y = defaultRect.y - guiTouchOffset.y; guiBoundary.max.y = defaultRect.y + guiTouchOffset.y; } } public void Disable() { gameObject.active = false; enumeratedJoysticks = false; } public void ResetJoystick() { if (joystickType != JoystickType.rotation) { //Don't do anything if turret mode // Release the finger control and set the joystick back to the default position gui.pixelInset = defaultRect; lastFingerId = -1; position = Vector2.zero; fingerDownPos = Vector2.zero; if ( touchPad ){ tmpclr = gui.color; tmpclr.a = 0.025f; gui.color = tmpclr; } } else { //gui.pixelInset = defaultRect; lastFingerId = -1; position = position; fingerDownPos = fingerDownPos; if ( touchPad ){ tmpclr = gui.color; tmpclr.a = 0.025f; gui.color = tmpclr; } } } public bool IsFingerDown() { return (lastFingerId != -1); } public void LatchedFinger( int fingerId ) { // If another joystick has latched this finger, then we must release it if ( lastFingerId == fingerId ) ResetJoystick(); } public void Update() { if ( !enumeratedJoysticks ) { // Collect all joysticks in the game, so we can relay finger latching messages joysticks = (Joystick[]) FindObjectsOfType( typeof(Joystick) ); enumeratedJoysticks = true; } //CHeck if distance is over the allowed amount //Get centerPosition //Get current position //Get distance //If over, don't allow int count = iPhoneInput.touchCount; // Adjust the tap time window while it still available if ( tapTimeWindow > 0 ) tapTimeWindow -= Time.deltaTime; else tapCount = 0; if ( count == 0 ) ResetJoystick(); else { for(int i = 0;i < count; i++) { iPhoneTouch touch = iPhoneInput.GetTouch(i); Vector2 guiTouchPos = touch.position - guiTouchOffset; bool shouldLatchFinger = false; if ( touchPad ) { if ( touchZone.Contains( touch.position ) ) shouldLatchFinger = true; } else if ( gui.HitTest( touch.position ) ) { shouldLatchFinger = true; } // Latch the finger if this is a new touch if ( shouldLatchFinger && ( lastFingerId == -1 || lastFingerId != touch.fingerId ) ) { if ( touchPad ) { tmpclr = gui.color; tmpclr.a = 0.15f; gui.color = tmpclr; lastFingerId = touch.fingerId; fingerDownPos = touch.position; fingerDownTime = Time.time; } lastFingerId = touch.fingerId; // Accumulate taps if it is within the time window if ( tapTimeWindow > 0 ) { tapCount++; print("tap" + tapCount.ToString()); } else { tapCount = 1; print("tap" + tapCount.ToString()); //Tell gameobject that player has tapped turret joystick if (joystickType == JoystickType.rotation) { //TODO: Call! } tapTimeWindow = tapTimeDelta; } // Tell other joysticks we've latched this finger foreach ( Joystick j in joysticks ) { if ( j != this ) j.LatchedFinger( touch.fingerId ); } } if ( lastFingerId == touch.fingerId ) { // Override the tap count with what the iPhone SDK reports if it is greater // This is a workaround, since the iPhone SDK does not currently track taps // for multiple touches if ( touch.tapCount > tapCount ) tapCount = touch.tapCount; if ( touchPad ) { // For a touchpad, let's just set the position directly based on distance from initial touchdown position.x = Mathf.Clamp( ( touch.position.x - fingerDownPos.x ) / ( touchZone.width / 2 ), -1, 1 ); position.y = Mathf.Clamp( ( touch.position.y - fingerDownPos.y ) / ( touchZone.height / 2 ), -1, 1 ); } else { // Change the location of the joystick graphic to match where the touch is tmprect = gui.pixelInset; tmprect.x = Mathf.Clamp( guiTouchPos.x, guiBoundary.min.x, guiBoundary.max.x ); tmprect.y = Mathf.Clamp( guiTouchPos.y, guiBoundary.min.y, guiBoundary.max.y ); //Check distance float distance = Vector2.Distance(new Vector2(defaultRect.x, defaultRect.y), new Vector2(tmprect.x, tmprect.y)); float angle = Vector2.Angle(new Vector2(defaultRect.x, defaultRect.y), new Vector2(tmprect.x, tmprect.y)); if (distance < allowedDistance) { //Ok gui.pixelInset = tmprect; } else { //This is where I don't know what to do... } } if ( touch.phase == iPhoneTouchPhase.Ended || touch.phase == iPhoneTouchPhase.Canceled ) ResetJoystick(); } } } if ( !touchPad ) { // Get a value between -1 and 1 based on the joystick graphic location position.x = ( gui.pixelInset.x + guiTouchOffset.x - guiCenter.x ) / guiTouchOffset.x; position.y = ( gui.pixelInset.y + guiTouchOffset.y - guiCenter.y ) / guiTouchOffset.y; } // Adjust for dead zone float absoluteX = Mathf.Abs( position.x ); float absoluteY = Mathf.Abs( position.y ); if ( absoluteX < deadZone.x ) { // Report the joystick as being at the center if it is within the dead zone position.x = 0; } else if ( normalize ) { // Rescale the output after taking the dead zone into account position.x = Mathf.Sign( position.x ) * ( absoluteX - deadZone.x ) / ( 1 - deadZone.x ); } if ( absoluteY < deadZone.y ) { // Report the joystick as being at the center if it is within the dead zone position.y = 0; } else if ( normalize ) { // Rescale the output after taking the dead zone into account position.y = Mathf.Sign( position.y ) * ( absoluteY - deadZone.y ) / ( 1 - deadZone.y ); } } } So the later portion of the code handles the updated position of the joystick thumb. This is where I'd like it to track the finger position in a direction it still is allowed to move (like if the finger is too far up and slightly to the +X I'd like to make sure the joystick is as close in X and Y as allowed within the radius) Thanks for reading!

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  • Reducing latency for different geographic regions on Amazon Cloud

    - by Shoaibi
    I have got an application which has three components Application code : Amazon EC2 US-EAST-1 instance Application images, and other static data : Amazon S3 with CloudFront Application Database : Amazon RDS In short i need something like Cloud Front for EC2. In long, people using this application from a different region say middle east will have faster static content downloading due to Cloud Front but there would be a lot of latency in communicating to EC2 instance. I want to use a budget friendly way of enhancing this. Launching Amazon Instances in every region that offer is sure a choice, but isn't really cheap, so would try to avoid it unless its last resort. Also say if my clients also need to communicate to the RDS database directly, is there some kind of solution which gives that kind of functionality mentioned above, but for RDS?

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  • 8-Puzzle Solution executes infinitely [migrated]

    - by Ashwin
    I am looking for a solution to 8-puzzle problem using the A* Algorithm. I found this project on the internet. Please see the files - proj1 and EightPuzzle. The proj1 contains the entry point for the program(the main() function) and EightPuzzle describes a particular state of the puzzle. Each state is an object of the 8-puzzle. I feel that there is nothing wrong in the logic. But it loops forever for these two inputs that I have tried : {8,2,7,5,1,6,3,0,4} and {3,1,6,8,4,5,7,2,0}. Both of them are valid input states. What is wrong with the code? Note For better viewing copy the code in a Notepad++ or some other text editor(which has the capability to recognize java source file) because there are lot of comments in the code. Since A* requires a heuristic, they have provided the option of using manhattan distance and a heuristic that calculates the number of misplaced tiles. And to ensure that the best heuristic is executed first, they have implemented a PriorityQueue. The compareTo() function is implemented in the EightPuzzle class. The input to the program can be changed by changing the value of p1d in the main() function of proj1 class. The reason I am telling that there exists solution for the two my above inputs is because the applet here solves them. Please ensure that you select 8-puzzle from teh options in the applet. EDITI gave this input {0,5,7,6,8,1,2,4,3}. It took about 10 seconds and gave a result with 26 moves. But the applet gave a result with 24 moves in 0.0001 seconds with A*. For quick reference I have pasted the the two classes without the comments : EightPuzzle import java.util.*; public class EightPuzzle implements Comparable <Object> { int[] puzzle = new int[9]; int h_n= 0; int hueristic_type = 0; int g_n = 0; int f_n = 0; EightPuzzle parent = null; public EightPuzzle(int[] p, int h_type, int cost) { this.puzzle = p; this.hueristic_type = h_type; this.h_n = (h_type == 1) ? h1(p) : h2(p); this.g_n = cost; this.f_n = h_n + g_n; } public int getF_n() { return f_n; } public void setParent(EightPuzzle input) { this.parent = input; } public EightPuzzle getParent() { return this.parent; } public int inversions() { /* * Definition: For any other configuration besides the goal, * whenever a tile with a greater number on it precedes a * tile with a smaller number, the two tiles are said to be inverted */ int inversion = 0; for(int i = 0; i < this.puzzle.length; i++ ) { for(int j = 0; j < i; j++) { if(this.puzzle[i] != 0 && this.puzzle[j] != 0) { if(this.puzzle[i] < this.puzzle[j]) inversion++; } } } return inversion; } public int h1(int[] list) // h1 = the number of misplaced tiles { int gn = 0; for(int i = 0; i < list.length; i++) { if(list[i] != i && list[i] != 0) gn++; } return gn; } public LinkedList<EightPuzzle> getChildren() { LinkedList<EightPuzzle> children = new LinkedList<EightPuzzle>(); int loc = 0; int temparray[] = new int[this.puzzle.length]; EightPuzzle rightP, upP, downP, leftP; while(this.puzzle[loc] != 0) { loc++; } if(loc % 3 == 0){ temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 1]; temparray[loc + 1] = 0; rightP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); rightP.setParent(this); children.add(rightP); }else if(loc % 3 == 1){ //add one child swaps with right temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 1]; temparray[loc + 1] = 0; rightP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); rightP.setParent(this); children.add(rightP); //add one child swaps with left temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 1]; temparray[loc - 1] = 0; leftP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); leftP.setParent(this); children.add(leftP); }else if(loc % 3 == 2){ // add one child swaps with left temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 1]; temparray[loc - 1] = 0; leftP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); leftP.setParent(this); children.add(leftP); } if(loc / 3 == 0){ //add one child swaps with lower temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 3]; temparray[loc + 3] = 0; downP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); downP.setParent(this); children.add(downP); }else if(loc / 3 == 1 ){ //add one child, swap with upper temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 3]; temparray[loc - 3] = 0; upP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); upP.setParent(this); children.add(upP); //add one child, swap with lower temparray = this.puzzle.clone(); temparray[loc] = temparray[loc + 3]; temparray[loc + 3] = 0; downP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); downP.setParent(this); children.add(downP); }else if (loc / 3 == 2 ){ //add one child, swap with upper temparray = this.puzzle.clone(); temparray[loc] = temparray[loc - 3]; temparray[loc - 3] = 0; upP = new EightPuzzle(temparray, this.hueristic_type, this.g_n + 1); upP.setParent(this); children.add(upP); } return children; } public int h2(int[] list) // h2 = the sum of the distances of the tiles from their goal positions // for each item find its goal position // calculate how many positions it needs to move to get into that position { int gn = 0; int row = 0; int col = 0; for(int i = 0; i < list.length; i++) { if(list[i] != 0) { row = list[i] / 3; col = list[i] % 3; row = Math.abs(row - (i / 3)); col = Math.abs(col - (i % 3)); gn += row; gn += col; } } return gn; } public String toString() { String x = ""; for(int i = 0; i < this.puzzle.length; i++){ x += puzzle[i] + " "; if((i + 1) % 3 == 0) x += "\n"; } return x; } public int compareTo(Object input) { if (this.f_n < ((EightPuzzle) input).getF_n()) return -1; else if (this.f_n > ((EightPuzzle) input).getF_n()) return 1; return 0; } public boolean equals(EightPuzzle test){ if(this.f_n != test.getF_n()) return false; for(int i = 0 ; i < this.puzzle.length; i++) { if(this.puzzle[i] != test.puzzle[i]) return false; } return true; } public boolean mapEquals(EightPuzzle test){ for(int i = 0 ; i < this.puzzle.length; i++) { if(this.puzzle[i] != test.puzzle[i]) return false; } return true; } } proj1 import java.util.*; public class proj1 { /** * @param args */ public static void main(String[] args) { int[] p1d = {1, 4, 2, 3, 0, 5, 6, 7, 8}; int hueristic = 2; EightPuzzle start = new EightPuzzle(p1d, hueristic, 0); int[] win = { 0, 1, 2, 3, 4, 5, 6, 7, 8}; EightPuzzle goal = new EightPuzzle(win, hueristic, 0); astar(start, goal); } public static void astar(EightPuzzle start, EightPuzzle goal) { if(start.inversions() % 2 == 1) { System.out.println("Unsolvable"); return; } // function A*(start,goal) // closedset := the empty set // The set of nodes already evaluated. LinkedList<EightPuzzle> closedset = new LinkedList<EightPuzzle>(); // openset := set containing the initial node // The set of tentative nodes to be evaluated. priority queue PriorityQueue<EightPuzzle> openset = new PriorityQueue<EightPuzzle>(); openset.add(start); while(openset.size() > 0){ // x := the node in openset having the lowest f_score[] value EightPuzzle x = openset.peek(); // if x = goal if(x.mapEquals(goal)) { // return reconstruct_path(came_from, came_from[goal]) Stack<EightPuzzle> toDisplay = reconstruct(x); System.out.println("Printing solution... "); System.out.println(start.toString()); print(toDisplay); return; } // remove x from openset // add x to closedset closedset.add(openset.poll()); LinkedList <EightPuzzle> neighbor = x.getChildren(); // foreach y in neighbor_nodes(x) while(neighbor.size() > 0) { EightPuzzle y = neighbor.removeFirst(); // if y in closedset if(closedset.contains(y)){ // continue continue; } // tentative_g_score := g_score[x] + dist_between(x,y) // // if y not in openset if(!closedset.contains(y)){ // add y to openset openset.add(y); // } // } // } } public static void print(Stack<EightPuzzle> x) { while(!x.isEmpty()) { EightPuzzle temp = x.pop(); System.out.println(temp.toString()); } } public static Stack<EightPuzzle> reconstruct(EightPuzzle winner) { Stack<EightPuzzle> correctOutput = new Stack<EightPuzzle>(); while(winner.getParent() != null) { correctOutput.add(winner); winner = winner.getParent(); } return correctOutput; } }

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  • Hyper-V virtual machine unable to get IP address from DHCP server running on same physical box

    - by Bronumski
    We have a Windows server 2008 R2 with two network cards running AD, DHCP, DNS and Hyper-V The first nic is setup with a static IP address and DHCP, WDS, and DNS are bound to it. The second nic is configured in Hyper-V to be only used by Hyper-V and has been automatically configured so that only the virtual switch is enabled on the adapter. DHCP and DNS work fine for all physical machines on the network. It also works for Virtual Machines running on another physical box. Virtual machines that are bound to the virtual switch network adapter are unable to get a IP address. If the virtual machine is given a static IP address with correct subnet, gateway and dns everything works. Has anyone else got this working?

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  • Increasing Your Internet Speed

    I';ve been writing just recently about slow broadband connections and discussing common methods used to improve line speeds. This week I was pointed in the direction of a little device which claims to... [Author: Chris Holgate - Computers and Internet - April 05, 2010]

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