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  • For a Javascript library, what is the best or standard way to support extensibility

    - by Michael Best
    Specifically, I want to support "plugins" that modify the behavior of parts of the library. I couldn't find much information on the web about this subject. But here are my ideas for how a library could be extensible. The library exports an object with both public and "protected" functions. A plugin can replace any of those functions, thus modifying the library's behavior. Advantages of this method are that it's simple and that the plugin's functions can have full access to the library's "protected" functions. Disadvantages are that the library may be harder to maintain with a larger set of exposed functions and it could be hard to debug if multiple plugins are involved (how to know which plugin modified which function?). The library provides an "add plugin" function that accepts an object with a specific interface. Internally, the library will use the plugin instead of it's own code if appropriate. With this method, the internals of the library can be rearranged more freely as long as it still supports the same plugin interface. This could also support having different plugin interfaces to modify different parts of the library. A disadvantage of this method is that the plugins may have to re-implement code that is already part of the library since the library's internal functions are not exported. The library provides a "set implementation" function that accepts an object inherited from a specific base object. The library's public API calls functions in the implementation object for any functionality that can be modified and the base implementation object includes the core functionality, with both external (to the API) and internal functions. A plugin creates a new implementation object, which inherits from the base object and replaces any functions it wants to modify. This combines advantages and disadvantages of both the other methods.

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  • Oracle Enterprise Manager Extensibility News - June 2014

    - by Joe Diemer
    Introducing Extensibility Exchange Version 2 On the heals of Enterprise Manager 12c Release 4 this week comes version 2.0 of the Extensibility Exchange.  A new theme allows optimal viewing on a number of different computing devices from large monitor displays to tablets to smartphones.   One of the first things you'll notice is a scrollable banner with the latest news related to Enterprise Manager and extensibility.  Along with the "slider" and the latest entries from Oracle and the Partner community, new features like a tag cloud and an auto-complete search box provide a better way to find the plug-in, connector or other Enterprise Manager entity you are looking for.  Once you find it, a content details page with specific info related to that particular entity will enable you to access it at the provider's site and also rate and comment on that particular item. You can also send an email from the content details page which is routed to the developer.   And if you want to use version 1 of the Extensibility Exchange instead, you will be able to do so via the "Classic" option.  Check it out today at http://www.oracle.com/goto/emextensibility. Recent Additions from Oracle's Partner Community A number of important 3rd party plug-ins have been contributed by Oracle's partner community, which can be accessed via the Extensibility Exchange or by clicking the links in this blog: Dell Open Manage Fusion I-O ION Accelerator NetApp SANtricity E-Series PostgreSQL by Blue Medora You can also check out the following best practices and labs available via the Exchange: Riverbed Stingray Traffic Manager Reference Architecture Datavail Alert Optimizer Custom Templates Apps Associates' Oracle Enterprise Manager "Test Drives" for Oracle Database 12c Management Oracle Enterprise Manager Monitoring Essentials Oracle Application Management Suite for Oracle E-Business Suite

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  • How are you using the Managed Extensibility Framework?

    - by dboarman
    I have been working with MEF for about 2 weeks. I started thinking about what MEF is for, researching to find out how to use MEF, and finally implementing a Host with 3 modules. The contracts are proving to be easy to grasp and the modules are easily managed. Although MEF has a very practical use, I am wondering to what extent? I mean, is everyone going to be rewriting existing applications for extensibility? Yes, that sounds, and is insanely impractical. Rhetorically speaking: how is MEF affecting the current trends in programming? have you begun looking for opportunities to use MEF? have you begun planning a major re-write of an existing app that may benefit from extensibility? That said, my questions are: how do I know when I should plan a new project with extensibility? how will I know if an existing project needs to be re-written for extensibility? Is anyone using MEF?

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  • Speaking about ASP.NET MVC Extensibility at the Umbraco CodeGarden10

    Next week Ill be speaking about ASP.NET MVC Extensibility at the MVC pre-conference during annual Umbraco CodeGarden conference in Copenhagen starting next June 23rd. The presentation will be split in the two parts (just before and just after lunch) and it will cover the most of the main extensibility points of ASP.NET MVC which I covered in my most popular post: 13 ASP.NET MVC extensibility points you have to know. And I will also talk about the new extensibility points introduced in ASP.NET MVC...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • android mobile development performance vs extensibility

    - by mixm
    im developing a game in android, and i've been thinking about subdividing many of the elements of the game (e.g. game objects) into separate classes and sub-classes. but i know that method calls to these objects will cause some overhead. would it be better to improve performance or to improve extensibility?

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  • Visual Studio 2010 Extensibility, MPF and language services

    - by MainMa
    Hi, I am trying to extend Visual Studio 2010 RC to be able to use a custom programming language. The first two things I've tried to do is a syntax highlight/Intellisense feature (easily done, thanks to "Ook!" sample from PDC09) and a possibility to create new project templates (i.e. be able to open *.myproj files). For this second task, I can't find any easy tutorials or samples. Most samples are for Visual Studio 2008 (as for IronPython integration) or even VS2003. The few samples available for VS2010 do not work (including MPFProj) or do not compile, and are too hard to understand. Is there any easy-to-understand sample, either using MPFProj or a standalone solution, showing how to integrate templates for a custom language inside Visual Studio 2010?

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  • Visual Studio Remote Debugging Extensibility

    - by Chris
    I'm trying to attach to a remote machine with code similar to the following: Debugger2 db (Debugger2)dte.Debugger; Transport trans = db.Transports.Item("Default"); Process2 proc2 = (Process2)db.GetProcesses(trans, "MACHINENAME").Item("SERVICENAME"); proc2.Attach2(); I've gotten it to work by logging on through remote desktop and manually starting the debugger, but I have to stay logged in. The problem is, I don't want to stay logged into the remote machine. Is there a way to automatically launch the debugger, similar to what happens when I attach through the IDE?

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  • Announcing the RTM of MvcExtensions (aka System.Web.Mvc.Extensibility)

    - by kazimanzurrashid
    I am proud to announce the v1.0 of MvcExtensions (previously known as System.Web.Extensibility). There has been quite a few changes and enhancements since the last release. Some of the major changes are: The Namespace has been changed to MvcExtensions from System.Web.Mvc.Extensibility to avoid the unnecessary confusion that it is in the .NET Framework or part of the ASP.NET MVC. The Project is now moved to CodePlex from the GitHub. The primary reason to start the project over GitHub was distributed version control which is no longer valid as CodePlex recently added the Mercurial support. There is nothing wrong with GitHub, it is an excellent place for managing your project. But CodePlex has always been the native place for .NET project. MVC 1.0 support has been dropped. I will be covering each features in my blog, so stay tuned!!!

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  • Enterprise Manager Extensibility Exchange – Version 1.1 Now Available!

    - by Joe Diemer
    Since its announcement at Oracle OpenWorld 2012, the Enterprise Manager Extensibility Exchange is becoming the source to access Enterprise Manager entities, including plug-ins, connectors, deployment procedures, assemblies, templates, and more.  Based on feedback, the Exchange has recently been updated so Enterprise Manager administrators can find and access Oracle and partner-built plug-ins and connectors easier. The Exchange enables anyone to contribute an Enterprise Manager entity through the “Contribute” tab, where information about the entity is captured and placed on the Exchange once it is approved.  The Exchange encourages comment through the Enterprise Manager Forum.  An Oracle partner can build a plug-in by accessing the Extensibility Development Kit (EDK) found at the Development Resources tab.  Oracle partners and customers can can also engage a partner that has built its practice specializing in plug-in development and deployment.  One of those partners is Blue Medora, which has effectively used the EDK to build plug-ins to manage non-Oracle targets.  Next week Blue Medora will be a "Guest Blogger" and tell a great story about heterogeneous datacenter management.Partners can also have their plug-ins validated through the Oracle Validated Integration (OVI) program.  NetApp is an example of a partner that recently built an Enterprise Manager plug-in and has validated it through the program.  Check back here in two weeks for their blog post describing the value of an Enterprise Manager "OVI" plug-in as well as discuss specifics the NetApp storage plug-in.  Check out the NetApp Enterprise Manager Validated Integration datasheet in the meantime. The Enterprise Manager Exchange is located at http://www.oracle.com/goto/EMExtensibility. Stay Connected: Twitter |  Facebook |  YouTube |  Linkedin |  Newsletter

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  • An Introduction to ASP.NET MVC Extensibility

    Because ASP.NET MVC has been designed with extensibility as its design principle; almost every logical step of the processing pipeline can be replaced with your own implementation. In fact, the best way to develop applications with ASP.NET MVC is to extend the system, Simone starts a series that explains how to implement extensions to ASP.NET MVC, starting with the ones at the beginning of the pipeline (routing extensions) and finishing with the view extensions points.

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  • ASP.NET Web Forms Extensibility: Providers

    - by Ricardo Peres
    Introduction This will be the first of a number of posts on ASP.NET extensibility. At this moment I don’t know exactly how many will be and I only know a couple of subjects that I want to talk about, so more will come in the next days. I have the sensation that the providers offered by ASP.NET are not widely know, although everyone uses, for example, sessions, they may not be aware of the extensibility points that Microsoft included. This post won’t go into details of how to configure and extend each of the providers, but will hopefully give some pointers on that direction. Canonical These are the most widely known and used providers, coming from ASP.NET 1, chances are, you have used them already. Good support for invoking client side, either from a .NET application or from JavaScript. Lots of server-side controls use them, such as the Login control for example. Membership The Membership provider is responsible for managing registered users, including creating new ones, authenticating them, changing passwords, etc. ASP.NET comes with two implementations, one that uses a SQL Server database and another that uses the Active Directory. The base class is Membership and new providers are registered on the membership section on the Web.config file, as well as parameters for specifying minimum password lengths, complexities, maximum age, etc. One reason for creating a custom provider would be, for example, storing membership information in a different database engine. 1: <membership defaultProvider="MyProvider"> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly"/> 4: </providers> 5: </membership> Role The Role provider assigns roles to authenticated users. The base class is Role and there are three out of the box implementations: XML-based, SQL Server and Windows-based. Also registered on Web.config through the roleManager section, where you can also say if your roles should be cached on a cookie. If you want your roles to come from a different place, implement a custom provider. 1: <roleManager defaultProvider="MyProvider"> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly" /> 4: </providers> 5: </roleManager> Profile The Profile provider allows defining a set of properties that will be tied and made available to authenticated or even anonymous ones, which must be tracked by using anonymous authentication. The base class is Profile and the only included implementation stores these settings in a SQL Server database. Configured through profile section, where you also specify the properties to make available, a custom provider would allow storing these properties in different locations. 1: <profile defaultProvider="MyProvider"> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly"/> 4: </providers> 5: </profile> Basic OK, I didn’t know what to call these, so Basic is probably as good as a name as anything else. Not supported client-side (doesn’t even make sense). Session The Session provider allows storing data tied to the current “session”, which is normally created when a user first accesses the site, even when it is not yet authenticated, and remains all the way. The base class and only included implementation is SessionStateStoreProviderBase and it is capable of storing data in one of three locations: In the process memory (default, not suitable for web farms or increased reliability); A SQL Server database (best for reliability and clustering); The ASP.NET State Service, which is a Windows Service that is installed with the .NET Framework (ok for clustering). The configuration is made through the sessionState section. By adding a custom Session provider, you can store the data in different locations – think for example of a distributed cache. 1: <sessionState customProvider=”MyProvider”> 2: <providers> 3: <add name=”MyProvider” type=”MyClass, MyAssembly” /> 4: </providers> 5: </sessionState> Resource A not so known provider, allows you to change the origin of localized resource elements. By default, these come from RESX files and are used whenever you use the Resources expression builder or the GetGlobalResourceObject and GetLocalResourceObject methods, but if you implement a custom provider, you can have these elements come from some place else, such as a database. The base class is ResourceProviderFactory and there’s only one internal implementation which uses these RESX files. Configuration is through the globalization section. 1: <globalization resourceProviderFactoryType="MyClass, MyAssembly" /> Health Monitoring Health Monitoring is also probably not so well known, and actually not a good name for it. First, in order to understand what it does, you have to know that ASP.NET fires “events” at specific times and when specific things happen, such as when logging in, an exception is raised. These are not user interface events and you can create your own and fire them, nothing will happen, but the Health Monitoring provider will detect it. You can configure it to do things when certain conditions are met, such as a number of events being fired in a certain amount of time. You define these rules and route them to a specific provider, which must inherit from WebEventProvider. Out of the box implementations include sending mails, logging to a SQL Server database, writing to the Windows Event Log, Windows Management Instrumentation, the IIS 7 Trace infrastructure or the debugger Trace. Its configuration is achieved by the healthMonitoring section and a reason for implementing a custom provider would be, for example, locking down a web application in the event of a significant number of failed login attempts occurring in a small period of time. 1: <healthMonitoring> 2: <providers> 3: <add name="MyProvider" type="MyClass, MyAssembly"/> 4: </providers> 5: </healthMonitoring> Sitemap The Sitemap provider allows defining the site’s navigation structure and associated required permissions for each node, in a tree-like fashion. Usually this is statically defined, and the included provider allows it, by supplying this structure in a Web.sitemap XML file. The base class is SiteMapProvider and you can extend it in order to supply you own source for the site’s structure, which may even be dynamic. Its configuration must be done through the siteMap section. 1: <siteMap defaultProvider="MyProvider"> 2: <providers><add name="MyProvider" type="MyClass, MyAssembly" /> 3: </providers> 4: </siteMap> Web Part Personalization Web Parts are better known by SharePoint users, but since ASP.NET 2.0 they are included in the core Framework. Web Parts are server-side controls that offer certain possibilities of configuration by clients visiting the page where they are located. The infrastructure handles this configuration per user or globally for all users and this provider is responsible for just that. The base class is PersonalizationProvider and the only included implementation stores settings on SQL Server. Add new providers through the personalization section. 1: <webParts> 2: <personalization defaultProvider="MyProvider"> 3: <providers> 4: <add name="MyProvider" type="MyClass, MyAssembly"/> 5: </providers> 6: </personalization> 7: </webParts> Build The Build provider is responsible for compiling whatever files are present on your web folder. There’s a base class, BuildProvider, and, as can be expected, internal implementations for building pages (ASPX), master pages (Master), user web controls (ASCX), handlers (ASHX), themes (Skin), XML Schemas (XSD), web services (ASMX, SVC), resources (RESX), browser capabilities files (Browser) and so on. You would write a build provider if you wanted to generate code from any kind of non-code file so that you have strong typing at development time. Configuration goes on the buildProviders section and it is per extension. 1: <buildProviders> 2: <add extension=".ext" type="MyClass, MyAssembly” /> 3: </buildProviders> New in ASP.NET 4 Not exactly new since they exist since 2010, but in ASP.NET terms, still new. Output Cache The Output Cache for ASPX pages and ASCX user controls is now extensible, through the Output Cache provider, which means you can implement a custom mechanism for storing and retrieving cached data, for example, in a distributed fashion. The base class is OutputCacheProvider and the only implementation is private. Configuration goes on the outputCache section and on each page and web user control you can choose the provider you want to use. 1: <caching> 2: <outputCache defaultProvider="MyProvider"> 3: <providers> 4: <add name="MyProvider" type="MyClass, MyAssembly"/> 5: </providers> 6: </outputCache> 7: </caching> Request Validation A big change introduced in ASP.NET 4 (and refined in 4.5, by the way) is the introduction of extensible request validation, by means of a Request Validation provider. This means we are not limited to either enabling or disabling event validation for all pages or for a specific page, but we now have fine control over each of the elements of the request, including cookies, headers, query string and form values. The base provider class is RequestValidator and the configuration goes on the httpRuntime section. 1: <httpRuntime requestValidationType="MyClass, MyAssembly" /> Browser Capabilities The Browser Capabilities provider is new in ASP.NET 4, although the concept exists from ASP.NET 2. The idea is to map a browser brand and version to its supported capabilities, such as JavaScript version, Flash support, ActiveX support, and so on. Previously, this was all hardcoded in .Browser files located in %WINDIR%\Microsoft.NET\Framework(64)\vXXXXX\Config\Browsers, but now you can have a class inherit from HttpCapabilitiesProvider and implement your own mechanism. Register in on the browserCaps section. 1: <browserCaps provider="MyClass, MyAssembly" /> Encoder The Encoder provider is responsible for encoding every string that is sent to the browser on a page or header. This includes for example converting special characters for their standard codes and is implemented by the base class HttpEncoder. Another implementation takes care of Anti Cross Site Scripting (XSS) attacks. Build your own by inheriting from one of these classes if you want to add some additional processing to these strings. The configuration will go on the httpRuntime section. 1: <httpRuntime encoderType="MyClass, MyAssembly" /> Conclusion That’s about it for ASP.NET providers. It was by no means a thorough description, but I hope I managed to raise your interest on this subject. There are lots of pointers on the Internet, so I only included direct references to the Framework classes and configuration sections. Stay tuned for more extensibility!

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  • Check your Embed Interop Types flag when doing Visual Studio extensibility work

    - by Daniel Cazzulino
    In case you didn’t notice, VS2010 adds a new property to assembly references in the properties window: Embed Interop Types: This property was introduced as a way to overcome the pain of deploying Primary Interop Assemblies. Read that blog post, it will help understand why you DON’T need it when doing VS extensibility (VSX) work. It's generally advisable when doing VSX development NOT to use Embed Interop Types, which is a feature intended mostly for office PIA scenarios where the PIA assemblies are HUGE and had to be shipped with your app. This is NEVER the case with VSX authoring. All interop assemblies you reference (EnvDTE, VS.Shell, etc.) are ALWAYS already there in the users' machine, and you NEVER need to distribute them. So embedding those types only increases your assembly size without a single benefit to you (the extension developer/author).... Read full article

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  • Three Hidden Extensibility Gems in ASP.NET 4

    ASP.NET 4 introduces a few new extensibility APIs that live the hermit lifestyle away from the public eye. Theyre not exactly hidden - they are well documented on MSDN - but they arent well publicized. Its about time we shine a spotlight on them. PreApplicationStartMethodAttribute This new attribute allows you to have code run way early in the ASP.NET pipeline as an application starts up. I mean way early, even before Application_Start. This happens to also be before code in your App_code folder...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • High level overview of Visual Studio Extensibility APIs

    - by Daniel Cazzulino
    If your head is dizzy with the myriad VS services and APIs, from EnvDTE to Shell.Interop, this should clarify a couple things. First a bit of background: APIs on EnvDTE (DTE for short, since that’s the entry point service you request from the environment) was originally an API intended to be used by macros. It’s also called the automation API. Most of the time, this is a simplified API that is easier to work with, but which doesn’t expose 100% of what VS is capable of doing. It’s also kind of the “rookie” way of doing VS extensibility (VSX for short), since most hardcore VSX devs sooner or later realize that they need to make the leap to the “serious” APIs. The “real” VSX APIs virtually always start with IVs, make heavy use of uint, ref/out parameters and HResults. These are the APIs that have been evolving for years and years, and there is a lot of COM baggage. ...Read full article

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  • MEF (Microsoft Extensibility Framework) made simple (ish)

    Microsoft Extensibility Framework or MEF is one of the great features in Silverlight, designed around making Silverlight applications more extensible generally and provides a much more complete story for the separation of concerns. MEF then begs the question 'Why we care?' and 'What can MEF really do?' and we will address that here.Let us talk about a real world example for a moment.Say you are a vertical selling corporation of some kind, meaning that you sell to companies that do similar things....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Coming Soon: Development and Extensibility Handbook from Oracle Press

    - by Oliver Steinmeier
    I had hoped to get my hands on a copy at OpenWorld, but it wasn't available yet from the printers.  But it's coming soon: The Oracle Fusion Applications Development and Extensibility Handbook. This book is promising to be a great resource for anyone interested in learning about our favorite topic.  And while I haven't read it yet, a look at the cover page image tells me that it's going to be a high-quality book.  That's because I have known one of the authors, Dhaval Mehta, for many years.  He recently left Oracle development for new challenges, but until then he was widely known as one of the most knowledgable Fusion Applications engineers.  And his co-authors have equally strong and complementary backgrounds.Here's what the book covers: Explore Oracle Fusion Applications components and architecture Plan, develop, debug, and deploy customizations Extend out-of-the-box functionality with Oracle JDeveloper Modify web applications using Oracle Composer Incorporate Oracle SOA Suite 11g composites Validate code through sandboxes and test environments Secure data using authorization, authentication, and encryption Design and distribute personalized BI reports Automate jobs with Oracle Enterprise Scheduler Change appearance and branding of your applications with the Oracle ADF Skin Editor   Expect a more detailed review of the book when it his your local bookseller's shelves (or Amazon).

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  • The NEW Oracle Enterprise Manager Extensibility Exchange

    - by Joe Diemer
    Oracle Enterprise Manager continues to expand its Eco-system with the NEW Extensibility Exchange! The Exchange offers a searchable listing of Enterprise Manager entities. Today it’s stocked with plug-ins and connectors for Enterprise Manager 12c and 11g. Anyone - partners, customers, ACE community members, anyone - can post an entity subject to approval of course. So in addition to plug-ins and connectors, the Exchange will have best practices, deployment procedures, templates, and essentially any Enterprise Manager entity that’s relevant. The Exchange provides Development Resources to guide contributors in the creation of plug-ins and connectors. A Community Resources page features plug-ins validated through the Oracle Validate Integration program as well as some other contributions important to customers.  You can also discover ways to get more involved with Enterprise Manager through the user and partner communities. The Exchange was announced in the October 2nd Enterprise Manager Partner Press Release  and is being presented at Oracle OpenWorld 2012 during the following sessions:    •    “Using Oracle Enterprise Manager to Manage Your Own Private Cloud” General Session – Tuesday Oct 2nd    •    “Managing Heterogeneous Environments with Oracle Enterprise Manager” Conference Session – Tuesday Oct 2nd    •    “Using Management Already Built into Oracle Products: Oracle Enterprise Manager” Oracle Partner Network Exchange Session – Wednesday Oct 3rd Check it out at http://www.oracle.com/goto/emextensibility, and let us know what you think by posting a comment below or clicking the "Forum" button at the Exchange itself.

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  • ASP.NET Web Forms Extensibility: Control Adapters

    - by Ricardo Peres
    All ASP.NET controls from version 2.0 can be associated with a control adapter. A control adapter is a class that inherits from ControlAdapter and it has the chance to interact with the control(s) it is targeting so as to change some of its properties or alter its output. I talked about control adapters before and they really a cool feature. The ControlAdapter class exposes virtual methods for some well known lifecycle events, OnInit, OnLoad, OnPreRender and OnUnload that closely match their Control counterparts, but are fired before them. Because the control adapter has a reference to its target Control, it can cast it to its concrete class and do something with it before its lifecycle events are actually fired. The adapter is also notified before the control is rendered (BeginRender), after their children are renderes (RenderChildren) and after itself is rendered (Render): this way the adapter can modify the control’s output. Control adapters may be specified for any class inheriting from Control, including abstract classes, web server controls and even pages. You can, for example, specify a control adapter for the WebControl and UserControl classes, but, curiously, not for Control itself. When specifying a control adapter for a page, it must inherit from PageAdapter instead of ControlAdapter. The adapter for a control, if specified, can be found on the protected Adapter property, and for a page, on the PageAdapter property. The first use of control adapters that came to my attention was for changing the output of standard ASP.NET web controls so that they were more based on CSS and less on HTML tables: it was the CSS Friendly Control Adapters project, now available at http://code.google.com/p/aspnetcontroladapters/. They are interesting because you specify them in one location and they apply anywhere a control of the target type is created. Mind you, it applies to controls declared on markup as well as controls created by code with the new operator. So, how do you use control adapters? The most usual way is through a browser definition file. In it, you specify a set of control adapters and their target controls, for a given browser. This browser definition file is a XML file with extension .Browser, and can either be global (%WINDIR%\Microsoft.NET\Framework64\vXXXX\Config\Browsers) or local to the web application, in which case, it must be placed inside the App_Browsers folder at the root of the web site. It looks like this: 1: <browsers> 2: <browser refID="Default"> 3: <controlAdapters> 4: <adapter controlType="System.Web.UI.WebControls.TextBox" adapterType="MyNamespace.TextBoxAdapter, MyAssembly" /> 5: </controlAdapters> 6: </browser> 7: </browsers> A browser definition file targets a specific browser, so you can have different definitions for Chrome, IE, Firefox, Opera, as well as for specific version of each of those (like IE8, Firefox3). Alternatively, if you set the target to Default, it will apply to all. The reason to pick a specific browser and version might be, for example, in order to circumvent some limitation present in that specific version, so that on markup you don’t need to be concerned with that. Another option is through the the current Browser object of the request: 1: this.Context.Request.Browser.Adapters.Add(typeof(TextBox).FullName, typeof(TextBoxAdapter).FullName); This must go very early on the page lifecycle, for example, on the OnPreInit event, or even on Application_Start. You have to specify the full class name for both the target control and the adapter. Of course, you have to do this for every request, because it won’t be persisted. As an example, you may know that the classic TextBox control renders an HTML input tag if its TextMode is set to SingleLine and a textarea if set to MultiLine. Because the textarea has no notion of maximum length, unlike the input, something must be done in order to enforce this. Here’s a simple suggestion: 1: public class TextBoxControlAdapter : ControlAdapter 2: { 3: protected TextBox Target 4: { 5: get 6: { 7: return (this.Control as TextBox); 8: } 9: } 10:  11: protected override void OnLoad(EventArgs e) 12: { 13: if ((this.Target.MaxLength > 0) && (this.Target.TextMode == TextBoxMode.MultiLine)) 14: { 15: if (this.Target.Page.ClientScript.IsClientScriptBlockRegistered("TextBox_KeyUp") == false) 16: { 17: if (this.Target.Page.ClientScript.IsClientScriptBlockRegistered(this.Target.Page.GetType(), "TextBox_KeyUp") == false) 18: { 19: String script = String.Concat("function TextBox_KeyUp(sender) { if (sender.value.length > ", this.Target.MaxLength, ") { sender.value = sender.value.substr(0, ", this.Target.MaxLength, "); } }\n"); 20:  21: this.Target.Page.ClientScript.RegisterClientScriptBlock(this.Target.Page.GetType(), "TextBox_KeyUp", script, true); 22: } 23:  24: this.Target.Attributes["onkeyup"] = "TextBox_KeyUp(this)"; 25: } 26: } 27: 28: base.OnLoad(e); 29: } 30: } What it does is, for every TextBox control, if it is set for multi line and has a defined maximum length, it injects some JavaScript that will filter out any content that exceeds this maximum length. This will occur for any TextBox that you may have on your site, or any class that inherits from it. You can use any of the previous options to register this adapter. Stay tuned for more ASP.NET Web Forms extensibility tips!

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  • Workshops, online content show how Oracle infuses simplicity, mobility, extensibility into user experience

    - by mvaughan
    By Kathy Miedema & Misha Vaughan, Oracle Applications User Experience Oracle has made a huge investment into the user experience of its many different software product families, and recent releases showcase big changes and features that aim to promote end user engagement and efficiency by streamlining navigation and simplifying the user interface. But making Oracle’s enterprise software great-looking and usable doesn’t stop when Oracle products go out the door. The Applications User Experience (UX) team recognizes that our customers may need to customize software to fit their work processes. And that’s why we provide tools such as user experience design patterns to help you maintain the Oracle user experience as you tailor your application to fit your business needs. Often, however, customers may need some context around user experience. How has the Oracle user experience been designed and constructed? Why is a good user experience important for users? How does understanding what goes into the user experience benefit the people who purchase the software for users? There’s a short answer to these questions, and you can read about it on Usable Apps. But truly understanding Oracle’s investment and seeing how it applies across product families occasionally requires a deeper dive into the Oracle user experience, especially if you’re an influencer or decision-maker about Oracle products. To help frame these decisions, the Communications & Outreach team has developed several targeted workshops that explore what Oracle means when it talks about user experience, and provides a roadmap into where the Oracle user experience is going. These workshops require non-disclosure agreements, and have been delivered to Oracle sales folks, Oracle partners, Oracle ACE Directors and ACEs, and a few customers. Some of these audience members have been developers or have a technical background; just as many did not. Here’s a breakdown of the kind of training you can get around the Oracle user experience from the OAUX Communications & Outreach team.For Partners: George Papazzian, Principal, Naviscent with Joyce Ohgi, Oracle Oracle Fusion Applications HCM Pre-Sales Seminar:  In concert with Worldwide Alliances  and  Channels under Applications Partner Enablement Director Jonathan Vinoskey’s guidance, the Applications User Experience team delivers a two-day workshop.  Day one focuses on Oracle Fusion Applications HCM and pre-sales strategy, and Day two focuses on positioning and leveraging Oracle’s investment in the Oracle Fusion Applications user experience.  The next workshops will occur on the following dates: December 4-5, 2013 @ Manchester, UK January 29-30, 2014 @ Reston, Virginia February 2014 @ Guadalajara, Mexico (email: Shannon Whiteman) March 11-12, 2014 @ Dubai, United Arab Emirates April 1-2, 2014 @ Chicago, Illinois Partner Advisory Board: A two-day board meeting in the U.S. and U.K. to discuss four main user experience areas for Oracle Fusion Applications: simplicity, visualization & analytics, mobility, & futures. This event is limited to Oracle Diamond Partners, UX bloggers, and key UX influencers and requires legal documentation.  We will be talking about the Oracle applications UX strategy and roadmap. Partner Implementation Training on User Interface: How to Build Great-Looking, Usable Apps:  In this two-day, hands-on workshop built around Oracle’s Application Development Framework, learn how to build desktop and mobile user interfaces and mobile user interfaces based on Oracle’s experience with Fusion Applications. This workshop is for partners with a technology background who are looking for ways to tailor Fusion Applications using ADF, or have built their own custom solutions using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs. Nov 5-6, 2013 @ Redwood Shores, CA, USA January 28-29th, 2014 @ Reston, Virginia, USA February 25-26, 2014 @ Guadalajara, Mexico March 9-10, 2014 @ Dubai, United Arab Emirates To register, contact [email protected] Simplified UI Customization & Extensibility:  Pilot workshop:  We will be reviewing the proposed content for communicating the user experience tool kit available with the next release of Oracle Fusion Applications.  Our core focus will be on what toolkit components our system implementors and independent software vendors will need to respond to customer demand, whether they are extending Fusion Applications, or building custom applications, that will need to leverage the simplified UI. Dec 11th, 2013 @ Reading, UK For information: contact [email protected] Private lab tour and demos: Interested in seeing what’s going on in the Apps UX Labs?  If you are headed to the San Francisco Bay Area, let us know. We can arrange a spin through our usability labs at headquarters. OAUX Expo: This open-house forum gives partners a look at what the UX team is working on, and showcases the next-generation user experiences in a demo environment where attendees can see and touch the applications. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For CustomersAngela Johnston, Gozel Aamoth, Teena Singh, and Yen Chan, Oracle Lab tours: See demos of soon-to-be-released products, and take a spin on usability research equipment such as our eye-tracker. Watch this video to get an idea of what you’ll see. Get our newsletter: Learn about newly released products and see where you can meet us at user group conferences. Participate in a feedback session: Join a focus group or customer feedback session to get an early look at user experience designs for the next generation of software, and provide your thoughts on how well it will work. Join the OUAB: The Oracle Usability Advisory Board meets several times a year to discuss trends in the workforce and provide direction on user experience designs. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Developers (customers, partners, and consultants): Plinio Arbizu, SP Solutions, Richard Bingham, Oracle, Balaji Kamepalli, EiSTechnoogies, Praveen Pillalamarri, EiSTechnologies How to Build Great-Looking, Usable Apps: This workshop is for attendees with a strong technology background who are looking for ways to tailor customer software using ADF. It includes an introduction to UX design patterns and provides tools to build usability-tested UX designs.  See above for dates and times. UX design patterns web site: Cut the length of your project down by months. Use these patterns to build out the task flow you need to develop for your users. The patterns have already been usability-tested and represent the best practices that the Oracle UX research team has found in its studies. UX Direct: Use the same methods that Oracle uses to develop its own user experiences. We help you define your users and their needs, and then provide direction on how to tailor the best user experience you can for them. For Oracle Sales Mike Klein, Jeremy Ashley, Brent White, Oracle Contact your local sales person for more information about the Oracle user experience and the training available from the Applications User Experience Communications & Outreach team. See customer-friendly user experience collateral ranging from the new simplified UI in Oracle Fusion Applications Release 7, to E-Business Suite user experience highlights, to Siebel, PeopleSoft, and JD Edwards user experience highlights.   Receive access to the same pre-sales and implementation training we provide to partners. For Oracle Sales only: Oracle-only training on the Oracle Fusion Applications UX Innovation Sales Kit.

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  • The Incremental Architect&rsquo;s Napkin - #5 - Design functions for extensibility and readability

    - by Ralf Westphal
    Originally posted on: http://geekswithblogs.net/theArchitectsNapkin/archive/2014/08/24/the-incremental-architectrsquos-napkin---5---design-functions-for.aspx The functionality of programs is entered via Entry Points. So what we´re talking about when designing software is a bunch of functions handling the requests represented by and flowing in through those Entry Points. Designing software thus consists of at least three phases: Analyzing the requirements to find the Entry Points and their signatures Designing the functionality to be executed when those Entry Points get triggered Implementing the functionality according to the design aka coding I presume, you´re familiar with phase 1 in some way. And I guess you´re proficient in implementing functionality in some programming language. But in my experience developers in general are not experienced in going through an explicit phase 2. “Designing functionality? What´s that supposed to mean?” you might already have thought. Here´s my definition: To design functionality (or functional design for short) means thinking about… well, functions. You find a solution for what´s supposed to happen when an Entry Point gets triggered in terms of functions. A conceptual solution that is, because those functions only exist in your head (or on paper) during this phase. But you may have guess that, because it´s “design” not “coding”. And here is, what functional design is not: It´s not about logic. Logic is expressions (e.g. +, -, && etc.) and control statements (e.g. if, switch, for, while etc.). Also I consider calling external APIs as logic. It´s equally basic. It´s what code needs to do in order to deliver some functionality or quality. Logic is what´s doing that needs to be done by software. Transformations are either done through expressions or API-calls. And then there is alternative control flow depending on the result of some expression. Basically it´s just jumps in Assembler, sometimes to go forward (if, switch), sometimes to go backward (for, while, do). But calling your own function is not logic. It´s not necessary to produce any outcome. Functionality is not enhanced by adding functions (subroutine calls) to your code. Nor is quality increased by adding functions. No performance gain, no higher scalability etc. through functions. Functions are not relevant to functionality. Strange, isn´t it. What they are important for is security of investment. By introducing functions into our code we can become more productive (re-use) and can increase evolvability (higher unterstandability, easier to keep code consistent). That´s no small feat, however. Evolvable code can hardly be overestimated. That´s why to me functional design is so important. It´s at the core of software development. To sum this up: Functional design is on a level of abstraction above (!) logical design or algorithmic design. Functional design is only done until you get to a point where each function is so simple you are very confident you can easily code it. Functional design an logical design (which mostly is coding, but can also be done using pseudo code or flow charts) are complementary. Software needs both. If you start coding right away you end up in a tangled mess very quickly. Then you need back out through refactoring. Functional design on the other hand is bloodless without actual code. It´s just a theory with no experiments to prove it. But how to do functional design? An example of functional design Let´s assume a program to de-duplicate strings. The user enters a number of strings separated by commas, e.g. a, b, a, c, d, b, e, c, a. And the program is supposed to clear this list of all doubles, e.g. a, b, c, d, e. There is only one Entry Point to this program: the user triggers the de-duplication by starting the program with the string list on the command line C:\>deduplicate "a, b, a, c, d, b, e, c, a" a, b, c, d, e …or by clicking on a GUI button. This leads to the Entry Point function to get called. It´s the program´s main function in case of the batch version or a button click event handler in the GUI version. That´s the physical Entry Point so to speak. It´s inevitable. What then happens is a three step process: Transform the input data from the user into a request. Call the request handler. Transform the output of the request handler into a tangible result for the user. Or to phrase it a bit more generally: Accept input. Transform input into output. Present output. This does not mean any of these steps requires a lot of effort. Maybe it´s just one line of code to accomplish it. Nevertheless it´s a distinct step in doing the processing behind an Entry Point. Call it an aspect or a responsibility - and you will realize it most likely deserves a function of its own to satisfy the Single Responsibility Principle (SRP). Interestingly the above list of steps is already functional design. There is no logic, but nevertheless the solution is described - albeit on a higher level of abstraction than you might have done yourself. But it´s still on a meta-level. The application to the domain at hand is easy, though: Accept string list from command line De-duplicate Present de-duplicated strings on standard output And this concrete list of processing steps can easily be transformed into code:static void Main(string[] args) { var input = Accept_string_list(args); var output = Deduplicate(input); Present_deduplicated_string_list(output); } Instead of a big problem there are three much smaller problems now. If you think each of those is trivial to implement, then go for it. You can stop the functional design at this point. But maybe, just maybe, you´re not so sure how to go about with the de-duplication for example. Then just implement what´s easy right now, e.g.private static string Accept_string_list(string[] args) { return args[0]; } private static void Present_deduplicated_string_list( string[] output) { var line = string.Join(", ", output); Console.WriteLine(line); } Accept_string_list() contains logic in the form of an API-call. Present_deduplicated_string_list() contains logic in the form of an expression and an API-call. And then repeat the functional design for the remaining processing step. What´s left is the domain logic: de-duplicating a list of strings. How should that be done? Without any logic at our disposal during functional design you´re left with just functions. So which functions could make up the de-duplication? Here´s a suggestion: De-duplicate Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Processing step 2 obviously was the core of the solution. That´s where real creativity was needed. That´s the core of the domain. But now after this refinement the implementation of each step is easy again:private static string[] Parse_string_list(string input) { return input.Split(',') .Select(s => s.Trim()) .ToArray(); } private static Dictionary<string,object> Compile_unique_strings(string[] strings) { return strings.Aggregate( new Dictionary<string, object>(), (agg, s) => { agg[s] = null; return agg; }); } private static string[] Serialize_unique_strings( Dictionary<string,object> dict) { return dict.Keys.ToArray(); } With these three additional functions Main() now looks like this:static void Main(string[] args) { var input = Accept_string_list(args); var strings = Parse_string_list(input); var dict = Compile_unique_strings(strings); var output = Serialize_unique_strings(dict); Present_deduplicated_string_list(output); } I think that´s very understandable code: just read it from top to bottom and you know how the solution to the problem works. It´s a mirror image of the initial design: Accept string list from command line Parse the input string into a true list of strings. Register each string in a dictionary/map/set. That way duplicates get cast away. Transform the data structure into a list of unique strings. Present de-duplicated strings on standard output You can even re-generate the design by just looking at the code. Code and functional design thus are always in sync - if you follow some simple rules. But about that later. And as a bonus: all the functions making up the process are small - which means easy to understand, too. So much for an initial concrete example. Now it´s time for some theory. Because there is method to this madness ;-) The above has only scratched the surface. Introducing Flow Design Functional design starts with a given function, the Entry Point. Its goal is to describe the behavior of the program when the Entry Point is triggered using a process, not an algorithm. An algorithm consists of logic, a process on the other hand consists just of steps or stages. Each processing step transforms input into output or a side effect. Also it might access resources, e.g. a printer, a database, or just memory. Processing steps thus can rely on state of some sort. This is different from Functional Programming, where functions are supposed to not be stateful and not cause side effects.[1] In its simplest form a process can be written as a bullet point list of steps, e.g. Get data from user Output result to user Transform data Parse data Map result for output Such a compilation of steps - possibly on different levels of abstraction - often is the first artifact of functional design. It can be generated by a team in an initial design brainstorming. Next comes ordering the steps. What should happen first, what next etc.? Get data from user Parse data Transform data Map result for output Output result to user That´s great for a start into functional design. It´s better than starting to code right away on a given function using TDD. Please get me right: TDD is a valuable practice. But it can be unnecessarily hard if the scope of a functionn is too large. But how do you know beforehand without investing some thinking? And how to do this thinking in a systematic fashion? My recommendation: For any given function you´re supposed to implement first do a functional design. Then, once you´re confident you know the processing steps - which are pretty small - refine and code them using TDD. You´ll see that´s much, much easier - and leads to cleaner code right away. For more information on this approach I call “Informed TDD” read my book of the same title. Thinking before coding is smart. And writing down the solution as a bunch of functions possibly is the simplest thing you can do, I´d say. It´s more according to the KISS (Keep It Simple, Stupid) principle than returning constants or other trivial stuff TDD development often is started with. So far so good. A simple ordered list of processing steps will do to start with functional design. As shown in the above example such steps can easily be translated into functions. Moving from design to coding thus is simple. However, such a list does not scale. Processing is not always that simple to be captured in a list. And then the list is just text. Again. Like code. That means the design is lacking visuality. Textual representations need more parsing by your brain than visual representations. Plus they are limited in their “dimensionality”: text just has one dimension, it´s sequential. Alternatives and parallelism are hard to encode in text. In addition the functional design using numbered lists lacks data. It´s not visible what´s the input, output, and state of the processing steps. That´s why functional design should be done using a lightweight visual notation. No tool is necessary to draw such designs. Use pen and paper; a flipchart, a whiteboard, or even a napkin is sufficient. Visualizing processes The building block of the functional design notation is a functional unit. I mostly draw it like this: Something is done, it´s clear what goes in, it´s clear what comes out, and it´s clear what the processing step requires in terms of state or hardware. Whenever input flows into a functional unit it gets processed and output is produced and/or a side effect occurs. Flowing data is the driver of something happening. That´s why I call this approach to functional design Flow Design. It´s about data flow instead of control flow. Control flow like in algorithms is of no concern to functional design. Thinking about control flow simply is too low level. Once you start with control flow you easily get bogged down by tons of details. That´s what you want to avoid during design. Design is supposed to be quick, broad brush, abstract. It should give overview. But what about all the details? As Robert C. Martin rightly said: “Programming is abot detail”. Detail is a matter of code. Once you start coding the processing steps you designed you can worry about all the detail you want. Functional design does not eliminate all the nitty gritty. It just postpones tackling them. To me that´s also an example of the SRP. Function design has the responsibility to come up with a solution to a problem posed by a single function (Entry Point). And later coding has the responsibility to implement the solution down to the last detail (i.e. statement, API-call). TDD unfortunately mixes both responsibilities. It´s just coding - and thereby trying to find detailed implementations (green phase) plus getting the design right (refactoring). To me that´s one reason why TDD has failed to deliver on its promise for many developers. Using functional units as building blocks of functional design processes can be depicted very easily. Here´s the initial process for the example problem: For each processing step draw a functional unit and label it. Choose a verb or an “action phrase” as a label, not a noun. Functional design is about activities, not state or structure. Then make the output of an upstream step the input of a downstream step. Finally think about the data that should flow between the functional units. Write the data above the arrows connecting the functional units in the direction of the data flow. Enclose the data description in brackets. That way you can clearly see if all flows have already been specified. Empty brackets mean “no data is flowing”, but nevertheless a signal is sent. A name like “list” or “strings” in brackets describes the data content. Use lower case labels for that purpose. A name starting with an upper case letter like “String” or “Customer” on the other hand signifies a data type. If you like, you also can combine descriptions with data types by separating them with a colon, e.g. (list:string) or (strings:string[]). But these are just suggestions from my practice with Flow Design. You can do it differently, if you like. Just be sure to be consistent. Flows wired-up in this manner I call one-dimensional (1D). Each functional unit just has one input and/or one output. A functional unit without an output is possible. It´s like a black hole sucking up input without producing any output. Instead it produces side effects. A functional unit without an input, though, does make much sense. When should it start to work? What´s the trigger? That´s why in the above process even the first processing step has an input. If you like, view such 1D-flows as pipelines. Data is flowing through them from left to right. But as you can see, it´s not always the same data. It get´s transformed along its passage: (args) becomes a (list) which is turned into (strings). The Principle of Mutual Oblivion A very characteristic trait of flows put together from function units is: no functional units knows another one. They are all completely independent of each other. Functional units don´t know where their input is coming from (or even when it´s gonna arrive). They just specify a range of values they can process. And they promise a certain behavior upon input arriving. Also they don´t know where their output is going. They just produce it in their own time independent of other functional units. That means at least conceptually all functional units work in parallel. Functional units don´t know their “deployment context”. They now nothing about the overall flow they are place in. They are just consuming input from some upstream, and producing output for some downstream. That makes functional units very easy to test. At least as long as they don´t depend on state or resources. I call this the Principle of Mutual Oblivion (PoMO). Functional units are oblivious of others as well as an overall context/purpose. They are just parts of a whole focused on a single responsibility. How the whole is built, how a larger goal is achieved, is of no concern to the single functional units. By building software in such a manner, functional design interestingly follows nature. Nature´s building blocks for organisms also follow the PoMO. The cells forming your body do not know each other. Take a nerve cell “controlling” a muscle cell for example:[2] The nerve cell does not know anything about muscle cells, let alone the specific muscel cell it is “attached to”. Likewise the muscle cell does not know anything about nerve cells, let a lone a specific nerve cell “attached to” it. Saying “the nerve cell is controlling the muscle cell” thus only makes sense when viewing both from the outside. “Control” is a concept of the whole, not of its parts. Control is created by wiring-up parts in a certain way. Both cells are mutually oblivious. Both just follow a contract. One produces Acetylcholine (ACh) as output, the other consumes ACh as input. Where the ACh is going, where it´s coming from neither cell cares about. Million years of evolution have led to this kind of division of labor. And million years of evolution have produced organism designs (DNA) which lead to the production of these different cell types (and many others) and also to their co-location. The result: the overall behavior of an organism. How and why this happened in nature is a mystery. For our software, though, it´s clear: functional and quality requirements needs to be fulfilled. So we as developers have to become “intelligent designers” of “software cells” which we put together to form a “software organism” which responds in satisfying ways to triggers from it´s environment. My bet is: If nature gets complex organisms working by following the PoMO, who are we to not apply this recipe for success to our much simpler “machines”? So my rule is: Wherever there is functionality to be delivered, because there is a clear Entry Point into software, design the functionality like nature would do it. Build it from mutually oblivious functional units. That´s what Flow Design is about. In that way it´s even universal, I´d say. Its notation can also be applied to biology: Never mind labeling the functional units with nouns. That´s ok in Flow Design. You´ll do that occassionally for functional units on a higher level of abstraction or when their purpose is close to hardware. Getting a cockroach to roam your bedroom takes 1,000,000 nerve cells (neurons). Getting the de-duplication program to do its job just takes 5 “software cells” (functional units). Both, though, follow the same basic principle. Translating functional units into code Moving from functional design to code is no rocket science. In fact it´s straightforward. There are two simple rules: Translate an input port to a function. Translate an output port either to a return statement in that function or to a function pointer visible to that function. The simplest translation of a functional unit is a function. That´s what you saw in the above example. Functions are mutually oblivious. That why Functional Programming likes them so much. It makes them composable. Which is the reason, nature works according to the PoMO. Let´s be clear about one thing: There is no dependency injection in nature. For all of an organism´s complexity no DI container is used. Behavior is the result of smooth cooperation between mutually oblivious building blocks. Functions will often be the adequate translation for the functional units in your designs. But not always. Take for example the case, where a processing step should not always produce an output. Maybe the purpose is to filter input. Here the functional unit consumes words and produces words. But it does not pass along every word flowing in. Some words are swallowed. Think of a spell checker. It probably should not check acronyms for correctness. There are too many of them. Or words with no more than two letters. Such words are called “stop words”. In the above picture the optionality of the output is signified by the astrisk outside the brackets. It means: Any number of (word) data items can flow from the functional unit for each input data item. It might be none or one or even more. This I call a stream of data. Such behavior cannot be translated into a function where output is generated with return. Because a function always needs to return a value. So the output port is translated into a function pointer or continuation which gets passed to the subroutine when called:[3]void filter_stop_words( string word, Action<string> onNoStopWord) { if (...check if not a stop word...) onNoStopWord(word); } If you want to be nitpicky you might call such a function pointer parameter an injection. And technically you´re right. Conceptually, though, it´s not an injection. Because the subroutine is not functionally dependent on the continuation. Firstly continuations are procedures, i.e. subroutines without a return type. Remember: Flow Design is about unidirectional data flow. Secondly the name of the formal parameter is chosen in a way as to not assume anything about downstream processing steps. onNoStopWord describes a situation (or event) within the functional unit only. Translating output ports into function pointers helps keeping functional units mutually oblivious in cases where output is optional or produced asynchronically. Either pass the function pointer to the function upon call. Or make it global by putting it on the encompassing class. Then it´s called an event. In C# that´s even an explicit feature.class Filter { public void filter_stop_words( string word) { if (...check if not a stop word...) onNoStopWord(word); } public event Action<string> onNoStopWord; } When to use a continuation and when to use an event dependens on how a functional unit is used in flows and how it´s packed together with others into classes. You´ll see examples further down the Flow Design road. Another example of 1D functional design Let´s see Flow Design once more in action using the visual notation. How about the famous word wrap kata? Robert C. Martin has posted a much cited solution including an extensive reasoning behind his TDD approach. So maybe you want to compare it to Flow Design. The function signature given is:string WordWrap(string text, int maxLineLength) {...} That´s not an Entry Point since we don´t see an application with an environment and users. Nevertheless it´s a function which is supposed to provide a certain functionality. The text passed in has to be reformatted. The input is a single line of arbitrary length consisting of words separated by spaces. The output should consist of one or more lines of a maximum length specified. If a word is longer than a the maximum line length it can be split in multiple parts each fitting in a line. Flow Design Let´s start by brainstorming the process to accomplish the feat of reformatting the text. What´s needed? Words need to be assembled into lines Words need to be extracted from the input text The resulting lines need to be assembled into the output text Words too long to fit in a line need to be split Does sound about right? I guess so. And it shows a kind of priority. Long words are a special case. So maybe there is a hint for an incremental design here. First let´s tackle “average words” (words not longer than a line). Here´s the Flow Design for this increment: The the first three bullet points turned into functional units with explicit data added. As the signature requires a text is transformed into another text. See the input of the first functional unit and the output of the last functional unit. In between no text flows, but words and lines. That´s good to see because thereby the domain is clearly represented in the design. The requirements are talking about words and lines and here they are. But note the asterisk! It´s not outside the brackets but inside. That means it´s not a stream of words or lines, but lists or sequences. For each text a sequence of words is output. For each sequence of words a sequence of lines is produced. The asterisk is used to abstract from the concrete implementation. Like with streams. Whether the list of words gets implemented as an array or an IEnumerable is not important during design. It´s an implementation detail. Does any processing step require further refinement? I don´t think so. They all look pretty “atomic” to me. And if not… I can always backtrack and refine a process step using functional design later once I´ve gained more insight into a sub-problem. Implementation The implementation is straightforward as you can imagine. The processing steps can all be translated into functions. Each can be tested easily and separately. Each has a focused responsibility. And the process flow becomes just a sequence of function calls: Easy to understand. It clearly states how word wrapping works - on a high level of abstraction. And it´s easy to evolve as you´ll see. Flow Design - Increment 2 So far only texts consisting of “average words” are wrapped correctly. Words not fitting in a line will result in lines too long. Wrapping long words is a feature of the requested functionality. Whether it´s there or not makes a difference to the user. To quickly get feedback I decided to first implement a solution without this feature. But now it´s time to add it to deliver the full scope. Fortunately Flow Design automatically leads to code following the Open Closed Principle (OCP). It´s easy to extend it - instead of changing well tested code. How´s that possible? Flow Design allows for extension of functionality by inserting functional units into the flow. That way existing functional units need not be changed. The data flow arrow between functional units is a natural extension point. No need to resort to the Strategy Pattern. No need to think ahead where extions might need to be made in the future. I just “phase in” the remaining processing step: Since neither Extract words nor Reformat know of their environment neither needs to be touched due to the “detour”. The new processing step accepts the output of the existing upstream step and produces data compatible with the existing downstream step. Implementation - Increment 2 A trivial implementation checking the assumption if this works does not do anything to split long words. The input is just passed on: Note how clean WordWrap() stays. The solution is easy to understand. A developer looking at this code sometime in the future, when a new feature needs to be build in, quickly sees how long words are dealt with. Compare this to Robert C. Martin´s solution:[4] How does this solution handle long words? Long words are not even part of the domain language present in the code. At least I need considerable time to understand the approach. Admittedly the Flow Design solution with the full implementation of long word splitting is longer than Robert C. Martin´s. At least it seems. Because his solution does not cover all the “word wrap situations” the Flow Design solution handles. Some lines would need to be added to be on par, I guess. But even then… Is a difference in LOC that important as long as it´s in the same ball park? I value understandability and openness for extension higher than saving on the last line of code. Simplicity is not just less code, it´s also clarity in design. But don´t take my word for it. Try Flow Design on larger problems and compare for yourself. What´s the easier, more straightforward way to clean code? And keep in mind: You ain´t seen all yet ;-) There´s more to Flow Design than described in this chapter. In closing I hope I was able to give you a impression of functional design that makes you hungry for more. To me it´s an inevitable step in software development. Jumping from requirements to code does not scale. And it leads to dirty code all to quickly. Some thought should be invested first. Where there is a clear Entry Point visible, it´s functionality should be designed using data flows. Because with data flows abstraction is possible. For more background on why that´s necessary read my blog article here. For now let me point out to you - if you haven´t already noticed - that Flow Design is a general purpose declarative language. It´s “programming by intention” (Shalloway et al.). Just write down how you think the solution should work on a high level of abstraction. This breaks down a large problem in smaller problems. And by following the PoMO the solutions to those smaller problems are independent of each other. So they are easy to test. Or you could even think about getting them implemented in parallel by different team members. Flow Design not only increases evolvability, but also helps becoming more productive. All team members can participate in functional design. This goes beyon collective code ownership. We´re talking collective design/architecture ownership. Because with Flow Design there is a common visual language to talk about functional design - which is the foundation for all other design activities.   PS: If you like what you read, consider getting my ebook “The Incremental Architekt´s Napkin”. It´s where I compile all the articles in this series for easier reading. I like the strictness of Function Programming - but I also find it quite hard to live by. And it certainly is not what millions of programmers are used to. Also to me it seems, the real world is full of state and side effects. So why give them such a bad image? That´s why functional design takes a more pragmatic approach. State and side effects are ok for processing steps - but be sure to follow the SRP. Don´t put too much of it into a single processing step. ? Image taken from www.physioweb.org ? My code samples are written in C#. C# sports typed function pointers called delegates. Action is such a function pointer type matching functions with signature void someName(T t). Other languages provide similar ways to work with functions as first class citizens - even Java now in version 8. I trust you find a way to map this detail of my translation to your favorite programming language. I know it works for Java, C++, Ruby, JavaScript, Python, Go. And if you´re using a Functional Programming language it´s of course a no brainer. ? Taken from his blog post “The Craftsman 62, The Dark Path”. ?

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  • A DirectoryCatalog class for Silverlight MEF (Managed Extensibility Framework)

    - by Dixin
    In the MEF (Managed Extension Framework) for .NET, there are useful ComposablePartCatalog implementations in System.ComponentModel.Composition.dll, like: System.ComponentModel.Composition.Hosting.AggregateCatalog System.ComponentModel.Composition.Hosting.AssemblyCatalog System.ComponentModel.Composition.Hosting.DirectoryCatalog System.ComponentModel.Composition.Hosting.TypeCatalog While in Silverlight, there is a extra System.ComponentModel.Composition.Hosting.DeploymentCatalog. As a wrapper of AssemblyCatalog, it can load all assemblies in a XAP file in the web server side. Unfortunately, in silverlight there is no DirectoryCatalog to load a folder. Background There are scenarios that Silverlight application may need to load all XAP files in a folder in the web server side, for example: If the Silverlight application is extensible and supports plug-ins, there would be a /ClinetBin/Plugins/ folder in the web server, and each pluin would be an individual XAP file in the folder. In this scenario, after the application is loaded and started up, it would like to load all XAP files in /ClinetBin/Plugins/ folder. If the aplication supports themes, there would be a /ClinetBin/Themes/ folder, and each theme would be an individual XAP file too. The application would qalso need to load all XAP files in /ClinetBin/Themes/. It is useful if we have a DirectoryCatalog: DirectoryCatalog catalog = new DirectoryCatalog("/Plugins"); catalog.DownloadCompleted += (sender, e) => { }; catalog.DownloadAsync(); Obviously, the implementation of DirectoryCatalog is easy. It is just a collection of DeploymentCatalog class. Retrieve file list from a directory Of course, to retrieve file list from a web folder, the folder’s “Directory Browsing” feature must be enabled: So when the folder is requested, it responses a list of its files and folders: This is nothing but a simple HTML page: <html> <head> <title>localhost - /Folder/</title> </head> <body> <h1>localhost - /Folder/</h1> <hr> <pre> <a href="/">[To Parent Directory]</a><br> <br> 1/3/2011 7:22 PM 185 <a href="/Folder/File.txt">File.txt</a><br> 1/3/2011 7:22 PM &lt;dir&gt; <a href="/Folder/Folder/">Folder</a><br> </pre> <hr> </body> </html> For the ASP.NET Deployment Server of Visual Studio, directory browsing is enabled by default: The HTML <Body> is almost the same: <body bgcolor="white"> <h2><i>Directory Listing -- /ClientBin/</i></h2> <hr width="100%" size="1" color="silver"> <pre> <a href="/">[To Parent Directory]</a> Thursday, January 27, 2011 11:51 PM 282,538 <a href="Test.xap">Test.xap</a> Tuesday, January 04, 2011 02:06 AM &lt;dir&gt; <a href="TestFolder/">TestFolder</a> </pre> <hr width="100%" size="1" color="silver"> <b>Version Information:</b>&nbsp;ASP.NET Development Server 10.0.0.0 </body> The only difference is, IIS’s links start with slash, but here the links do not. Here one way to get the file list is read the href attributes of the links: [Pure] private IEnumerable<Uri> GetFilesFromDirectory(string html) { Contract.Requires(html != null); Contract.Ensures(Contract.Result<IEnumerable<Uri>>() != null); return new Regex( "<a href=\"(?<uriRelative>[^\"]*)\">[^<]*</a>", RegexOptions.IgnoreCase | RegexOptions.CultureInvariant) .Matches(html) .OfType<Match>() .Where(match => match.Success) .Select(match => match.Groups["uriRelative"].Value) .Where(uriRelative => uriRelative.EndsWith(".xap", StringComparison.Ordinal)) .Select(uriRelative => { Uri baseUri = this.Uri.IsAbsoluteUri ? this.Uri : new Uri(Application.Current.Host.Source, this.Uri); uriRelative = uriRelative.StartsWith("/", StringComparison.Ordinal) ? uriRelative : (baseUri.LocalPath.EndsWith("/", StringComparison.Ordinal) ? baseUri.LocalPath + uriRelative : baseUri.LocalPath + "/" + uriRelative); return new Uri(baseUri, uriRelative); }); } Please notice the folders’ links end with a slash. They are filtered by the second Where() query. The above method can find files’ URIs from the specified IIS folder, or ASP.NET Deployment Server folder while debugging. To support other formats of file list, a constructor is needed to pass into a customized method: /// <summary> /// Initializes a new instance of the <see cref="T:System.ComponentModel.Composition.Hosting.DirectoryCatalog" /> class with <see cref="T:System.ComponentModel.Composition.Primitives.ComposablePartDefinition" /> objects based on all the XAP files in the specified directory URI. /// </summary> /// <param name="uri"> /// URI to the directory to scan for XAPs to add to the catalog. /// The URI must be absolute, or relative to <see cref="P:System.Windows.Interop.SilverlightHost.Source" />. /// </param> /// <param name="getFilesFromDirectory"> /// The method to find files' URIs in the specified directory. /// </param> public DirectoryCatalog(Uri uri, Func<string, IEnumerable<Uri>> getFilesFromDirectory) { Contract.Requires(uri != null); this._uri = uri; this._getFilesFromDirectory = getFilesFromDirectory ?? this.GetFilesFromDirectory; this._webClient = new Lazy<WebClient>(() => new WebClient()); // Initializes other members. } When the getFilesFromDirectory parameter is null, the above GetFilesFromDirectory() method will be used as default. Download the directory’s XAP file list Now a public method can be created to start the downloading: /// <summary> /// Begins downloading the XAP files in the directory. /// </summary> public void DownloadAsync() { this.ThrowIfDisposed(); if (Interlocked.CompareExchange(ref this._state, State.DownloadStarted, State.Created) == 0) { this._webClient.Value.OpenReadCompleted += this.HandleOpenReadCompleted; this._webClient.Value.OpenReadAsync(this.Uri, this); } else { this.MutateStateOrThrow(State.DownloadCompleted, State.Initialized); this.OnDownloadCompleted(new AsyncCompletedEventArgs(null, false, this)); } } Here the HandleOpenReadCompleted() method is invoked when the file list HTML is downloaded. Download all XAP files After retrieving all files’ URIs, the next thing becomes even easier. HandleOpenReadCompleted() just uses built in DeploymentCatalog to download the XAPs, and aggregate them into one AggregateCatalog: private void HandleOpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { Exception error = e.Error; bool cancelled = e.Cancelled; if (Interlocked.CompareExchange(ref this._state, State.DownloadCompleted, State.DownloadStarted) != State.DownloadStarted) { cancelled = true; } if (error == null && !cancelled) { try { using (StreamReader reader = new StreamReader(e.Result)) { string html = reader.ReadToEnd(); IEnumerable<Uri> uris = this._getFilesFromDirectory(html); Contract.Assume(uris != null); IEnumerable<DeploymentCatalog> deploymentCatalogs = uris.Select(uri => new DeploymentCatalog(uri)); deploymentCatalogs.ForEach( deploymentCatalog => { this._aggregateCatalog.Catalogs.Add(deploymentCatalog); deploymentCatalog.DownloadCompleted += this.HandleDownloadCompleted; }); deploymentCatalogs.ForEach(deploymentCatalog => deploymentCatalog.DownloadAsync()); } } catch (Exception exception) { error = new InvalidOperationException(Resources.InvalidOperationException_ErrorReadingDirectory, exception); } } // Exception handling. } In HandleDownloadCompleted(), if all XAPs are downloaded without exception, OnDownloadCompleted() callback method will be invoked. private void HandleDownloadCompleted(object sender, AsyncCompletedEventArgs e) { if (Interlocked.Increment(ref this._downloaded) == this._aggregateCatalog.Catalogs.Count) { this.OnDownloadCompleted(e); } } Exception handling Whether this DirectoryCatelog can work only if the directory browsing feature is enabled. It is important to inform caller when directory cannot be browsed for XAP downloading. private void HandleOpenReadCompleted(object sender, OpenReadCompletedEventArgs e) { Exception error = e.Error; bool cancelled = e.Cancelled; if (Interlocked.CompareExchange(ref this._state, State.DownloadCompleted, State.DownloadStarted) != State.DownloadStarted) { cancelled = true; } if (error == null && !cancelled) { try { // No exception thrown when browsing directory. Downloads the listed XAPs. } catch (Exception exception) { error = new InvalidOperationException(Resources.InvalidOperationException_ErrorReadingDirectory, exception); } } WebException webException = error as WebException; if (webException != null) { HttpWebResponse webResponse = webException.Response as HttpWebResponse; if (webResponse != null) { // Internally, WebClient uses WebRequest.Create() to create the WebRequest object. Here does the same thing. WebRequest request = WebRequest.Create(Application.Current.Host.Source); Contract.Assume(request != null); if (request.CreatorInstance == WebRequestCreator.ClientHttp && // Silverlight is in client HTTP handling, all HTTP status codes are supported. webResponse.StatusCode == HttpStatusCode.Forbidden) { // When directory browsing is disabled, the HTTP status code is 403 (forbidden). error = new InvalidOperationException( Resources.InvalidOperationException_ErrorListingDirectory_ClientHttp, webException); } else if (request.CreatorInstance == WebRequestCreator.BrowserHttp && // Silverlight is in browser HTTP handling, only 200 and 404 are supported. webResponse.StatusCode == HttpStatusCode.NotFound) { // When directory browsing is disabled, the HTTP status code is 404 (not found). error = new InvalidOperationException( Resources.InvalidOperationException_ErrorListingDirectory_BrowserHttp, webException); } } } this.OnDownloadCompleted(new AsyncCompletedEventArgs(error, cancelled, this)); } Please notice Silverlight 3+ application can work either in client HTTP handling, or browser HTTP handling. One difference is: In browser HTTP handling, only HTTP status code 200 (OK) and 404 (not OK, including 500, 403, etc.) are supported In client HTTP handling, all HTTP status code are supported So in above code, exceptions in 2 modes are handled differently. Conclusion Here is the whole DirectoryCatelog’s looking: Please click here to download the source code, a simple unit test is included. This is a rough implementation. And, for convenience, some design and coding are just following the built in AggregateCatalog class and Deployment class. Please feel free to modify the code, and please kindly tell me if any issue is found.

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