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  • Hybrid IT or Cloud Initiative – a Perfect Enterprise Architecture Maturation Opportunity

    - by Ted McLaughlan
    Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} All too often in the growth and maturation of Enterprise Architecture initiatives, the effort stalls or is delayed due to lack of “applied traction”. By this, I mean the EA activities - whether targeted towards compliance, risk mitigation or value opportunity propositions – may not be attached to measurable, active, visible projects that could advance and prove the value of EA. EA doesn’t work by itself, in a vacuum, without collaborative engagement and a means of proving usefulness. A critical vehicle to this proof is successful orchestration and use of assets and investment resources to meet a high-profile business objective – i.e. a successful project. More and more organizations are now exploring and considering some degree of IT outsourcing, buying and using external services and solutions to deliver their IT and business requirements – vs. building and operating in-house, in their own data centers. The rapid growth and success of “Cloud” services makes some decisions easier and some IT projects more successful, while dramatically lowering IT risks and enabling rapid growth. This is particularly true for “Software as a Service” (SaaS) applications, which essentially are complete web applications hosted and delivered over the Internet. Whether SaaS solutions – or any kind of cloud solution - are actually, ultimately the most cost-effective approach truly depends on the organization’s business and IT investment strategy. This leads us to Enterprise Architecture, the connectivity between business strategy and investment objectives, and the capabilities purchased or created to meet them. If an EA framework already exists, the approach to selecting a cloud-based solution and integrating it with internal IT systems (i.e. a “Hybrid IT” solution) is well-served by leveraging EA methods. If an EA framework doesn’t exist, or is simply not mature enough to address complex, integrated IT objectives – a hybrid IT/cloud initiative is the perfect project to advance and prove the value of EA. Why is this? For starters, the success of any complex IT integration project - spanning multiple systems, contracts and organizations, public and private – depends on active collaboration and coordination among the project stakeholders. For a hybrid IT initiative, inclusive of one or more cloud services providers, the IT services, business workflow and data governance challenges alone can be extremely complex, requiring many diverse layers of organizational expertise and authority. Establishing subject matter expertise, authorities and strategic guidance across all the disciplines involved in a hybrid-IT or hybrid-cloud system requires top-level, comprehensive experience and collaborative leadership. Tools and practices reflecting industry expertise and EA alignment can also be very helpful – such as Oracle’s “Cloud Candidate Selection Tool”. Using tools like this, and facilitating this critical collaboration by leading, organizing and coordinating the input and expertise into a shared, referenceable, reusable set of authority models and practices – this is where EA shines, and where Enterprise Architects can be most valuable. The “enterprise”, in this case, becomes something greater than the core organization – it includes internal systems, public cloud services, 3rd-party IT platforms and datacenters, distributed users and devices; a whole greater than the sum of its parts. Through facilitated project collaboration, leading to identification or creation of solid governance models and processes, a durable and useful Enterprise Architecture framework will usually emerge by itself, if not actually identified and managed as such. The transition from planning collaboration to actual coordination, where the program plan, schedule and resources become synchronized and aligned to other investments in the organization portfolio, is where EA methods and artifacts appear and become most useful. The actual scope and use of these artifacts, in the context of this project, can then set the stage for the most desirable, helpful and pragmatic form of the now-maturing EA framework and community of practice. Considering or starting a hybrid-IT or hybrid-cloud initiative? Running into some complex relationship challenges? This is the perfect time to take advantage of your new, growing or possibly latent Enterprise Architecture practice.

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  • Managing multiple references of the same game entity in different places using IDs

    - by vargonian
    I've seen great questions on similar topics, but none that addressed this particular method: Given that I have multiple collections of game entities in my [XNA Game Studio] game, with many entities belonging to multiple lists, I'm considering ways I could keep track of whenever an entity is destroyed and remove it from the lists it belongs to. A lot of potential methods seem sloppy/convoluted, but I'm reminded of a way I've seen before in which, instead of having multiple collections of game entities, you have collections of game entity IDs instead. These IDs map to game entities via a central "database" (perhaps just a hash table). So, whenever any bit of code wants to access a game entity's members, it first checks to see if it's even in the database still. If not, it can react accordingly. Is this a sound approach? It seems that it would eliminate many of the risks/hassles of storing multiple lists, with the tradeoff being the cost of the lookup every time you want to access an object.

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  • How to optimize a one language website's SEO for foreign languages?

    - by moomoochoo
    DETAILS I have a website that's content is in English. It is a niche website with a global market. However I would like users to be able to find the website using their own language. The scenario I envision is that the searcher is looking for the English content, but is searching in their own language. An example could be someone looking for "downloadable English crosswords." MY IDEAS Buy ccTLDs and have them permanently redirect to subdirectories on domain.com. The subdirectories would contain html sitemaps in the target language e.g.-Redirect domain.fr to domain.com/fr OR perhaps it would be better to maintain domain.fr as an independent site in the target language with the html sitemap linking to pages on domain.com ? QUESTION Are the above methods good/bad? What are some other ways I can optimize SEO for foreign languages?

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  • Reading the tea leaves from Windows Azure support

    - by jamiet
    A few idle thoughts… Three months ago I had an issue regarding Windows Azure where I was unable to login to the management portal. At the time I contacted Azure support, the issue was soon resolved and I thought no more about it. Until today that is when I received an email from Azure support providing a detailed analysis of the root cause, the fix and moreover precise details about when and where things occurred. The email itself is interesting and I have included the entirety of it below. A few things were interesting to me: The level of detail and the diligence in investigating and reporting the issue I found really rather impressive. They even outline the number of users that were affected (127 in case you can’t be bothered reading). Compare this to the quite pathetic support that another division within Microsoft, Skype, provided to Greg Low recently: Skype support and dead parrot sketches   This line: “Windows Azure performed a planned change from using the Microsoft account service (formerly Windows Live ID) to the Azure Active Directory (AAD) as its primary authentication mechanism on August 24th. This change was made to enable future innovation in the area of authentication – particularly for organizationally owned identities, identity federation, stronger authentication methods and compliance certification. ” I also found to be particularly interesting. I have long thought that one of the reasons Microsoft has proved to be such a money-making machine in the enterprise is because they provide the infrastructure and then upsell on top of that – and nothing is more infrastructural than Active Directory. It has struck me of late that they are trying to make the same play of late in the cloud by tying all their services into Azure Active Directory and here we see a clear indication of that by making AAD the authentication mechanism for anyone using Windows Azure. I get the feeling that we’re going to hear much much more about AAD in the future; isn’t it about time we could log on to SQL Azure Windows Azure SQL Database without resorting to SQL authentication, for example? And why do Microsoft have two identity providers – Microsoft Account (aka Windows Live ID) and AAD – isn’t it about time those things were combined? As I said, just some idle thoughts. Below is the transcript of the email if you are interested. @Jamiet  This is regarding the support request <redacted> where in you were not able to login into the windows azure management portal with live id. We are providing you with the summary, root cause analysis and information about permanent fix: Incident Title: You were unable to access Windows Azure Portal after Microsoft Account to Azure Active Directory account Migration. Service Impacted: Management Portal Incident Start Date and Time: 8/24/2012 4:30:00 PM Date and Time Service was Restored: 10/17/2012 12:00:00 AM Summary: Windows Azure performed a planned change from using the Microsoft account service (formerly Windows Live ID) to the Azure Active Directory (AAD) as its primary authentication mechanism on August 24th.   This change was made to enable future innovation in the area of authentication – particularly for organizationally owned identities, identity federation, stronger authentication methods and compliance certification.   While this migration was largely transparent to Windows Azure users, a small number of users whose sign-in names were part of a Windows Live Custom Domain were unable to login.   This incompatibility was not discovered during the Quality Assurance testing phase prior to the migration. Customer Impact: Customers whose sign-in names were part of a Windows Live Custom Domain were unable to sign-in the Management Portal after ~4:00 p.m. PST on August 24th, 2012.   We determined that the issue did impact at least 127 users in 98 of these Windows Live Custom Domains and had a maximum potential impact of 1,110 users in total. Root Cause: The root cause of the issue was an incompatibility in the AAD authentication service to handle logins from Microsoft accounts whose sign-in names were part of a Windows Live Custom Domains.  This issue was not discovered during the Quality Assurance testing phase prior to the migration from Microsoft Account (MSA) to AAD. Mitigations: The issue was mitigated for the majority of affected users by 8:20 a.m. PST on August 25th, 2012 by running some internal scripts to correct many known Windows Live Custom Domains.   The remaining affected domains fell into two categories: Windows Live Custom Domains that were not corrected by 8/25/2012. An additional 48 Windows Live Custom Domains were fixed in the weeks following the incident within 2 business days after the AAD team received an escalation from product support regarding those accounts. Windows Live Custom domains that were also provisioned in Office365. Some of the affected Windows Live Custom Domains had already been provisioned in AAD because their owners signed up for Office365 which is a service that also uses AAD.   In these cases the Azure customers had to work around the issue by renaming their Microsoft Account or using a different Microsoft Account to administer their Azure subscription. Permanent Fix: The Azure Active Directory team permanently fixed the issue for all customers on 10/17/2012 in an upgraded release of the AAD service.

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  • Understanding Unity3d physics: where is the force applied?

    - by Heisenbug
    I'm trying to understand which is the right way to apply forces to a RigidBody. I noticed that there are AddForce and AddRelativeForce methods, one applied in world space coordinate system meanwhile the other in the local space. The thing that I do not understand is the following: usually in physics library (es. Bullet) we can specify the force vector and also the force application point. How can I do this in Unity? Is it possible to apply a force vector in a specific point relative to the given RigidBody coordinate system? Where does AddForce apply the force?

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  • Structure vs. programming

    - by ChristopherW
    Is it bad that I often find myself spending more time on program structure than actually writing code inside methods? Is this common? I feel I spend more time laying the foundation than actually building the house (metaphorically). While I understand that without a good foundation the house will cave in, but does it legitimately need to take half of the project to finalize code structure? I understand design patterns, and I know where to go if I need help on choosing one, but often I find myself doubting my own choices.

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  • API always returns JSONObject or JSONArray Best practices

    - by Michael Laffargue
    I'm making an API that will return data in JSON. I also wanted on client side to make an utility class to call this API. Something like : JSONObject sendGetRequest(Url url); JSONObject sendPostRequest(Url url, HashMap postData); However sometimes the API send back array of object [{id:1},{id:2}] I now got two choices (): Make the method test for JSONArray or JSONObject and send back an Object that I will have to cast in the caller Make a method that returns JSONObject and one for JSONArray (like sendGetRequestAndReturnAsJSONArray) Make the server always send Arrays even for one element Make the server always send Objects wrapping my Array I going for the two last methods since I think it would be a good thing to force the API to send consistent type of data. But what would be the best practice (if one exist). Always send arrays? or always send objects?

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  • Procedural object generation and unique identification

    - by 2080
    My question relates to procedural content generation and data management of the emerging objects in a database. I assume a networked game, with a server-client model. Unspecified objects in the game world are generated while the game is running with procedural algorithms (for example perlin noise). The players (/clients) can modify the properties of these objects, but have to notify the server of these changes. How could this communication address unique objects, so that both the server and the client know of which object they are speaking? Not only the inner properties of the objects can differ, but also visible, such as the position. When the player wants to select one of these objects the game has to find out the id - does anyone know which methods or algorithms can accomplish that?

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  • How to deal with "software end-of-life" situations?

    - by rwong
    When a vendor declares that they no longer intend to provide any support or services to a piece of software (and stated the intent to exit the business - offering no upgrade paths), and stated that customers must pay a nominal fee in order to have the existing data exported, what kind of recourse do programmers/customers have? Things I can think of: Need to purchase spare hardware and set up a spare environment on which the software can continue to operate. Various data export methods which do not require vendor involvement. (For example, screen scraping, printing to image followed by re-scanning, etc) Parallel systems where staff will duplicate the old data into a new system manually or semi-automatically Legal means, in case the vendor is in financial trouble Any other ideas? Assuming that there is no "circumvention" involved (no DRM, no DMCA), is data recovery or reverse engineering legal/acceptable?

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  • Best practices for upgrading user data when updating versions of software

    - by Javy
    In my code I check the current version of the software on launch and compare it to the version stored in the user's data file(s). If the version is newer, then I call different methods to update the old data to the newer data version, if necessary. I usually have to make a new method to convert the data with each update that changes user data in some way, and cannot remove the old ones in case there was someone who missed an update. So the app must be able to go through each method call and update their data until they get their data current. With larger data sets, this could be a problem. In addition, I recently had a brief discussion with another StackOverflow user this and he indicated he always appended a date stamp to the filename to manage data versions, although his reasoning as to why this was better than storing the version data in the file itself was unclear. Since I've rarely seen management of user data versions in books I've read, I'm curious what are the best practices for naming user data files and procedures for updating older data to newer versions.

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  • How to improve programming skills?

    - by Mike
    I'm very new to programming. I started learning PHP about half a year ago, so I do know something. I can write small functions, I can export and import information from a database and I can make a website. I don't know OOP principles and I don't know about objects and classes. Should I move to OOP principles and learn about classes, methods and objects? If not, what should I do? Continue writing simple code? How can a programmer write his/her own API? Is OOP necessary to do this? So how can i improve my skills? I love programming. I spend my 24/7 on it, so any help will be appreciated.

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  • How Uranium Refinement Works [Video]

    - by Jason Fitzpatrick
    While building a nuclear weapon is a complex task in and of itself, the most difficult part is refining uranium. In this informative video, Bill Hammack explains. Weapons and power plants require uranium that contains a greater amount of the isotope uranium-235 than found in natural uranium, which is mostly uranium-238. He outlines the key difficulty in separating the two isotope: They have nearly identical properties. He explains the two key methods for separation: Gas diffusion and centrifuges. What Keeps Nuclear Weapons from Proliferating HTG Explains: What Is Two-Factor Authentication and Should I Be Using It? HTG Explains: What Is Windows RT and What Does It Mean To Me? HTG Explains: How Windows 8′s Secure Boot Feature Works & What It Means for Linux

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  • Is having 'Util' classes a cause for concern? [closed]

    - by Matt Fenwick
    I sometimes create 'Util' classes which primarily serve to hold methods and values that don't really seem to belong elsewhere. But every time I create one of these classes, I think "uh-oh, I'm gonna regret this later ...", because I read somewhere that it's bad. But on the other hand, there seem to be two compelling (at least for me) cases for them: implementation secrets that are used in multiple classes within a package providing useful functionality to augment a class, without cluttering its interface Am I on the way to destruction? What you say !! Should I refactor?

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  • Expressions that are idiomatic in one language but not used or impossible in another

    - by Tungsten
    I often find myself working in unfamiliar languages. I like to read code written by others and then jump in and write something myself before going back and learning the corners of each language. To speed up this process, it really helps to know a few of the idioms you'll encounter ahead of time. Some of these, I've found are fairly unique. In Python you might do something like this: '\n'.join(listOfThings) Not all languages allow you to call methods on string literals like this. In C, you can write a loop like this: int i = 50; while(i--) { /* do something 50 times */ } C lets you decrement in the loop condition expression. Most more modern languages disallow this. Do you have any other good examples? I'm interested in often used constructions not odd corner cases.

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  • Python lower_case_with_underscores style convention: underscores not popular?

    - by squirrel
    PEP8 recommends using lowercase, with words separated by underscores as necessary to improve readability for variable and function names. I've seen this interpreted as lower_case_with_underscores by most people, although in practice and in Python's native methods it seems like lowercasewithoutunderscores is more popular. It seems like following PEP8 strictly would be awkward since it seems to suggest mixing both lower_case_with_underscores and lowercasewithoutunderscores, which would be inconsistent. What is your interpretation of PEP8's variable names, and what do you actually use in practice? (Personally, I like lowerCamelCase as a compromise between readability and ease of typing.)

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  • Should I sacrifice code succintness to ensure the narrowest variable scope? [duplicate]

    - by David Scholefield
    This question already has an answer here: Is the usage of internal scope blocks within a function bad style? 3 answers In many languages (e.g. both Perl and Java - which are the two languages I work most with) it is possible to narrow the scope of local variables by declaring them within a block. Although it adds extra code length (the opening and closing block braces), and possibly reduces readability, should I create blocks purely to narrow the scope of variables to the statements that use the variables and to uphold the principle of narrowest scope or does this sacrifice succinctness and readability just to unnecessarily uphold an agreed 'best practice' principle? I usually declare local variables to functions/methods at the start of the function to aid readability, but I could not do this, and just create blocks throughout the function and declare the variables throughout the code - within those blocks - to narrow their scope.

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  • In a browser, is it best to use one huge spritesheet or many (10000) different PNG's?

    - by Nick
    I'm creating a game in jQuery, where I use about 10000 32x32 tiles. Until now, I have been using them all separately (no sprite sheet). An average map uses about 2000 tiles (sometimes re-used PNG's but all separate divs) and the performance ranges from stable (Chrome) to a bit laggy (Firefox). Each of these divs are positioned absolutely using CSS. They do not need to be updated every tick, just when a new map is loaded. Would it be better for performance to use spritesheet methods for the divs using CSS background-positioning, like gameQuery does? Thank you in advance!

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  • What is the term that means "keeping the arguments for different API calls as similar as possible"?

    - by larson4
    There is a word which I can never remember... it expresses a design goal that API calls (or functions or methods or whatever) should be as similar as reasonably possible in their argument patterns. It may also extend to naming as well. In other words, all other things being equal, it is probably bad to have these three functions: deleteUser(email) petRemove(petId,species) destroyPlanet(planetName,starName) if instead you could have deleteUser(userId) deletePet(petId) deletePlanet(planetId) What is the word for this concept? I keep thinking it's "orthogonal" but it definitely isn't. Its a very important concept, and to me it's one of the biggest things that makes some APIs a joy to work with (because once you learn a few things you can pretty much use everything without looking at doco), and others a pain (because every function is done inconsistently).

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  • How to choose, set and use keywords while structuring a website?

    - by mechdeveloper
    I have been working on my personal website for sometime, I think I have been doing a good technical job, but, unfortunately I did a terrible job while structuring the website because I didn't care about the keywords I was going to use. Although it is my personal website, I'd like to mention the main objective is the blog of the website, so I'd like that the keywords were related to the content that it is in the blog, at present google webmaster tools is displaying a lot of keywords that has nothing to do with the content of the website, and some SEO reporting websites such as woorank says that the keyword optimization of the website is awful, So I have 3 questions: How to choose, set and use keywords while structuring a website? OPTIONAL: which are all the methods and sources used by search engines to collect the keywords of a website? there are some high profile websites that aren't optimized on this as well, should I concerned about this anyway?, is there anything more important that I should be concerned about? (if you want to see the website please check my profile)

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  • When should one use "out" parameters?

    - by qegal
    In Objective-C, there are several methods like initWithContentsOfFile:encoding:error: where one passes in a reference to an NSError object for the error: parameter. In this example, the value of the NSError object passed in can change based on what goes on at runtime when the method is being called and whether the body of the method was executed in a certain way successfully. In a way I think of this NSError object as sort of like a second return value from the method, and only differs from an object anObject in the statement return anObject; in that when this statement is called, execution leaves the method. So my question is, not only in the context of error handling in Objective-C, but in general, when should one use an "out" parameter in place of returning said value in a return statement?

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  • Gnome extensions don't work! I've tried everything!

    - by Nightshaxx
    When I go to https://extensions.gnome.org/, and try to install an extension, it clicks on, but nothing happens to my shell. Then, when I reload the page, the slider has turned off. Here are the things I have tried: I tried Chrome, Firefox, and Opera adding http://extensions.gnome.org to my allow plugin list in google chrome and made sure gnome-intigration is enabled I made a new firefox profile and tried installing it I reset my gnome shell settings (How do I reset GNOME to the defaults?) - this link actually broke my system, as now I can't log in to any desktop environment, the only way I can get to Unity, is by logging in to another desktop environment like cinnimon (which doesn't work) , then immediately logging into unity. Whenever I try to just log into unity or pretty much any other desktop environment, it logs in, but then seems to crash, and log out. Sometimes I even get quick glances of the Unity bar before it crashes I tried-re installing gnome None of these methods worked!! Thank you in advance!!

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  • Software/Application needed to store and organize random content [on hold]

    - by Rami.Shareef
    I have the need to store random contents (on my local hard drive/ laptop hard drive) for personal use so I can look these contents up later on when I need them. What I mean by random content is one of the following: Some sort of code Random fact Css / html / Javascript tips Or anything I might find interesting and want to keep for future reference I want to look up these entries by tags, the software should give me the ability to associate every entry with one tag or more. I have been having difficult time find applications offer this functionality, it is like a local database with search ability and easy data-entry methods. I can build one, but I don't have the time to invest in doing so. Can you refer me to any application/software that can do that, it would be great. It does not matter if it is paid or free.

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  • Develop open-source library and get donations for it?

    - by Robottinosino
    I have a nice open-source library in mind to write. It would take a few months to develop properly and I would need to stop supporting myself though other projects. Could anybody share experiences and best-known-methods to get some sort of financial support through the Internet whilst developing free, open-source code? Or, phrased more directly: which systems apart from "PayPal" are in use by programmers to get donations for open-source code? Provide a list. Optionally, sort the list as if it were a recommendation in descending order of positive experiences made with each system. Optionally, share a tidbit of your success story getting this kind of financial support. Optionally: give an indication as to how much money can be made that way? (I heard Vim's author could support himself just with donations at some point?)

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  • Navigation in a #WP7 application with MVVM Light

    - by Laurent Bugnion
    In MVVM applications, it can be a bit of a challenge to send instructions to the view (for example a page) from a viewmodel. Thankfully, we have good tools at our disposal to help with that. In his excellent series “MVVM Light Toolkit soup to nuts”, Jesse Liberty proposes one approach using the MVVM Light messaging infrastructure. While this works fine, I would like to show here another approach using what I call a “view service”, i.e. an abstracted service that is invoked from the viewmodel, and implemented on the view. Multiple kinds of view services In fact, I use view services quite often, and even started standardizing them for the Windows Phone 7 applications I work on. If there is interest, I will be happy to show other such view services, for example Animation services, responsible to start/stop animations on the view. Dialog service, in charge of displaying messages to the user and gathering feedback. Navigation service, in charge of navigating to a given page directly from the viewmodel. In this article, I will concentrate on the navigation service. The INavigationService interface In most WP7 apps, the navigation service is used in quite a straightforward way. We want to: Navigate to a given URI. Go back. Be notified when a navigation is taking place, and be able to cancel. The INavigationService interface is quite simple indeed: public interface INavigationService { event NavigatingCancelEventHandler Navigating; void NavigateTo(Uri pageUri); void GoBack(); } Obviously, this interface can be extended if necessary, but in most of the apps I worked on, I found that this covers my needs. The NavigationService class It is possible to nicely pack the navigation service into its own class. To do this, we need to remember that all the PhoneApplicationPage instances use the same instance of the navigation service, exposed through their NavigationService property. In fact, in a WP7 application, it is the main frame (RootFrame, of type PhoneApplicationFrame) that is responsible for this task. So, our implementation of the NavigationService class can leverage this. First the class will grab the PhoneApplicationFrame and store a reference to it. Also, it registers a handler for the Navigating event, and forwards the event to the listening viewmodels (if any). Then, the NavigateTo and the GoBack methods are implemented. They are quite simple, because they are in fact just a gateway to the PhoneApplicationFrame. The whole class is as follows: public class NavigationService : INavigationService { private PhoneApplicationFrame _mainFrame; public event NavigatingCancelEventHandler Navigating; public void NavigateTo(Uri pageUri) { if (EnsureMainFrame()) { _mainFrame.Navigate(pageUri); } } public void GoBack() { if (EnsureMainFrame() && _mainFrame.CanGoBack) { _mainFrame.GoBack(); } } private bool EnsureMainFrame() { if (_mainFrame != null) { return true; } _mainFrame = Application.Current.RootVisual as PhoneApplicationFrame; if (_mainFrame != null) { // Could be null if the app runs inside a design tool _mainFrame.Navigating += (s, e) => { if (Navigating != null) { Navigating(s, e); } }; return true; } return false; } } Exposing URIs I find that it is a good practice to expose each page’s URI as a constant. In MVVM Light applications, a good place to do that is the ViewModelLocator, which already acts like a central point of setup for the views and their viewmodels. Note that in some cases, it is necessary to expose the URL as a string, for instance when a query string needs to be passed to the view. So for example we could have: public static readonly Uri MainPageUri = new Uri("/MainPage.xaml", UriKind.Relative); public const string AnotherPageUrl = "/AnotherPage.xaml?param1={0}&param2={1}"; Creating and using the NavigationService Normally, we only need one instance of the NavigationService class. In cases where you use an IOC container, it is easy to simply register a singleton instance. For example, I am using a modified version of a super simple IOC container, and so I can register the navigation service as follows: SimpleIoc.Register<INavigationService, NavigationService>(); Then, it can be resolved where needed with: SimpleIoc.Resolve<INavigationService>(); Or (more frequently), I simply declare a parameter on the viewmodel constructor of type INavigationService and let the IOC container do its magic and inject the instance of the NavigationService when the viewmodel is created. On supported platforms (for example Silverlight 4), it is also possible to use MEF. Or, of course, we can simply instantiate the NavigationService in the ViewModelLocator, and pass this instance as a parameter of the viewmodels’ constructor, injected as a property, etc… Once the instance has been passed to the viewmodel, it can be used, for example with: NavigationService.NavigateTo(ViewModelLocator.ComparisonPageUri); Testing Thanks to the INavigationService interface, navigation can be mocked and tested when the viewmodel is put under unit test. Simply implement and inject a mock class, and assert that the methods are called as they should by the viewmodel. Conclusion As usual, there are multiple ways to code a solution answering your needs. I find that view services are a really neat way to delegate view-specific responsibilities such as animation, dialogs and of course navigation to other classes through an abstracted interface. In some cases, such as the NavigationService class exposed here, it is even possible to standardize the implementation and pack it in a class library for reuse. I hope that this sample is useful! Happy coding. Laurent   Laurent Bugnion (GalaSoft) Subscribe | Twitter | Facebook | Flickr | LinkedIn

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  • Why is JavaScript not used for classical application development (compiled software)?

    - by Jose Faeti
    During my years of web development with JavaScript, I come to the conclusion that it's an incredible powerful language, and you can do amazing things with it. It offers a rich set of features, like: Dynamic typing First-class functions Nested functions Closures Functions as methods Functions as Object constructors Prototype-based Objects-based (almost everything is an object) Regex Array and Object literals It seems to me that almost everything can be achieved with this kind of language, you can also emulate OO programming, since it provides great freedom and many different coding styles. With more software-oriented custom functionalities (I/O, FileSystem, Input devices, etc.) I think it will be great to develop applications with. Though, as far as I know, it's only used in web development or in existing softwares as a scripting language only. Only recently, maybe thanks to the V8 Engine, it's been used more for other kind of tasks (see node.js for example). Why until now it's only be relegated only to web development? What is keeping it away from software development?

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