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• Windows Azure Mobile Services: New support for iOS apps, Facebook/Twitter/Google identity, Emails, SMS, Blobs, Service Bus and more

  - by ScottGu

  A few weeks ago I blogged about Windows Azure Mobile Services - a new capability in Windows Azure that makes it incredibly easy to connect your client and mobile applications to a scalable cloud backend. Earlier today we delivered a number of great improvements to Windows Azure Mobile Services.  New features include: iOS support – enabling you to connect iPhone and iPad apps to Mobile Services Facebook, Twitter, and Google authentication support with Mobile Services Blob, Table, Queue, and Service Bus support from within your Mobile Service Sending emails from your Mobile Service (in partnership with SendGrid) Sending SMS messages from your Mobile Service (in partnership with Twilio) Ability to deploy mobile services in the West US region All of these improvements are now live in production and available to start using immediately. Below are more details on them: iOS Support This week we delivered initial support for connecting iOS based devices (including iPhones and iPads) to Windows Azure Mobile Services.  Like the rest of our Windows Azure SDK, we are delivering the native iOS libraries to enable this under an open source (Apache 2.0) license on GitHub.  We’re excited to get your feedback on this new library through our forum and GitHub issues list, and we welcome contributions to the SDK. To create a new iOS app or connect an existing iOS app to your Mobile Service, simply select the “iOS” tab within the Quick Start view of a Mobile Service within the Windows Azure Portal – and then follow either the “Create a new iOS app” or “Connect to an existing iOS app” link below it: Clicking either of these links will expand and display step-by-step instructions for how to build an iOS application that connects with your Mobile Service: Read this getting started tutorial to walkthrough how you can build (in less than 5 minutes) a simple iOS “Todo List” app that stores data in Windows Azure.  Then follow the below tutorials to explore how to use the iOS client libraries to store data and authenticate users. Get Started with data in Mobile Services for iOS Get Started with authentication in Mobile Services for iOS Facebook, Twitter, and Google Authentication Support Our initial preview of Mobile Services supported the ability to authenticate users of mobile apps using Microsoft Accounts (formerly called Windows Live ID accounts).  This week we are adding the ability to also authenticate users using Facebook, Twitter, and Google credentials.  These are now supported with both Windows 8 apps as well as iOS apps (and a single app can support multiple forms of identity simultaneously – so you can offer your users a choice of how to login). The below tutorials walkthrough how to register your Mobile Service with an identity provider: How to register your app with Microsoft Account How to register your app with Facebook How to register your app with Twitter How to register your app with Google The tutorials above walkthrough how to obtain a client ID and a secret key from the identity provider. You can then click on the “Identity” tab of your Mobile Service (within the Windows Azure Portal) and save these values to enable server-side authentication with your Mobile Service: You can then write code within your client or mobile app to authenticate your users to the Mobile Service.  For example, below is the code you would write to have them login to the Mobile Service using their Facebook credentials: Windows Store App (using C#): var user = await App.MobileService                     .LoginAsync(MobileServiceAuthenticationProvider.Facebook); iOS app (using Objective C): UINavigationController *controller = [self.todoService.client     loginViewControllerWithProvider:@"facebook"     completion:^(MSUser *user, NSError *error) {        //... }]; Learn more about authenticating Mobile Services using Microsoft Account, Facebook, Twitter, and Google from these tutorials: Get started with authentication in Mobile Services for Windows Store (C#) Get started with authentication in Mobile Services for Windows Store (JavaScript) Get started with authentication in Mobile Services for iOS Using Windows Azure Blob, Tables and ServiceBus with your Mobile Services Mobile Services provide a simple but powerful way to add server logic using server scripts. These scripts are associated with the individual CRUD operations on your mobile service’s tables. Server scripts are great for data validation, custom authorization logic (e.g. does this user participate in this game session), augmenting CRUD operations, sending push notifications, and other similar scenarios.   Server scripts are written in JavaScript and are executed in a secure server-side scripting environment built using Node.js.  You can edit these scripts and save them on the server directly within the Windows Azure Portal: In this week’s release we have added the ability to work with other Windows Azure services from your Mobile Service server scripts.  This is supported using the existing “azure” module within the Windows Azure SDK for Node.js.  For example, the below code could be used in a Mobile Service script to obtain a reference to a Windows Azure Table (after which you could query it or insert data into it):     var azure = require('azure');     var tableService = azure.createTableService("<< account name >>",                                                 "<< access key >>"); Follow the tutorials on the Windows Azure Node.js dev center to learn more about working with Blob, Tables, Queues and Service Bus using the azure module. Sending emails from your Mobile Service In this week’s release we have also added the ability to easily send emails from your Mobile Service, building on our partnership with SendGrid. Whether you want to add a welcome email upon successful user registration, or make your app alert you of certain usage activities, you can do this now by sending email from Mobile Services server scripts. To get started, sign up for SendGrid account at http://sendgrid.com . Windows Azure customers receive a special offer of 25,000 free emails per month from SendGrid. To sign-up for this offer, or get more information, please visit http://www.sendgrid.com/azure.html . One you signed up, you can add the following script to your Mobile Service server scripts to send email via SendGrid service:     var sendgrid = new SendGrid('<< account name >>', '<< password >>');       sendgrid.send({         to: '<< enter email address here >>',         from: '<< enter from address here >>',         subject: 'New to-do item',         text: 'A new to-do was added: ' + item.text     }, function (success, message) {         if (!success) {             console.error(message);         }     }); Follow the Send email from Mobile Services with SendGrid tutorial to learn more. Sending SMS messages from your Mobile Service SMS is a key communication medium for mobile apps - it comes in handy if you want your app to send users a confirmation code during registration, allow your users to invite their friends to install your app or reach out to mobile users without a smartphone. Using Mobile Service server scripts and Twilio’s REST API, you can now easily send SMS messages to your app.  To get started, sign up for Twilio account. Windows Azure customers receive 1000 free text messages when using Twilio and Windows Azure together. Once signed up, you can add the following to your Mobile Service server scripts to send SMS messages:     var httpRequest = require('request');     var account_sid = "<< account SID >>";     var auth_token = "<< auth token >>";       // Create the request body     var body = "From=" + from + "&To=" + to + "&Body=" + message;       // Make the HTTP request to Twilio     httpRequest.post({         url: "https://" + account_sid + ":" + auth_token +              "@api.twilio.com/2010-04-01/Accounts/" + account_sid + "/SMS/Messages.json",         headers: { 'content-type': 'application/x-www-form-urlencoded' },         body: body     }, function (err, resp, body) {         console.log(body);     }); I’m excited to be speaking at the TwilioCon conference this week, and will be showcasing some of the cool scenarios you can now enable with Twilio and Windows Azure Mobile Services. Mobile Services availability in West US region Our initial preview of Windows Azure Mobile Services was only supported in the US East region of Windows Azure.  As with every Windows Azure service, overtime we will extend Mobile Services to all Windows Azure regions. With this week’s preview update we’ve added support so that you can now create your Mobile Service in the West US region as well: Summary The above features are all now live in production and are available to use immediately.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using Mobile Services today. Visit the Windows Azure Mobile Developer Center to learn more about how to build apps with Mobile Services. We’ll have even more new features and enhancements coming later this week – including .NET 4.5 support for Windows Azure Web Sites.  Keep an eye out on my blog for details as new features become available. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• Announcing: Great Improvements to Windows Azure Web Sites

  - by ScottGu

  I’m excited to announce some great improvements to the Windows Azure Web Sites capability we first introduced earlier this summer.  Today’s improvements include: a new low-cost shared mode scaling option, support for custom domains with shared and reserved mode web-sites using both CNAME and A-Records (the later enabling naked domains), continuous deployment support using both CodePlex and GitHub, and FastCGI extensibility.  All of these improvements are now live in production and available to start using immediately. New “Shared” Scaling Tier Windows Azure allows you to deploy and host up to 10 web-sites in a free, shared/multi-tenant hosting environment. You can start out developing and testing web sites at no cost using this free shared mode, and it supports the ability to run web sites that serve up to 165MB/day of content (5GB/month).  All of the capabilities we introduced in June with this free tier remain the same with today’s update. Starting with today’s release, you can now elastically scale up your web-site beyond this capability using a new low-cost “shared” option (which we are introducing today) as well as using a “reserved instance” option (which we’ve supported since June).  Scaling to either of these modes is easy.  Simply click on the “scale” tab of your web-site within the Windows Azure Portal, choose the scaling option you want to use with it, and then click the “save” button.  Changes take only seconds to apply and do not require any code to be changed, nor the app to be redeployed: Below are some more details on the new “shared” option, as well as the existing “reserved” option: Shared Mode With today’s release we are introducing a new low-cost “shared” scaling mode for Windows Azure Web Sites.  A web-site running in shared mode is deployed in a shared/multi-tenant hosting environment.  Unlike the free tier, though, a web-site in shared mode has no quotas/upper-limit around the amount of bandwidth it can serve.  The first 5 GB/month of bandwidth you serve with a shared web-site is free, and then you pay the standard “pay as you go” Windows Azure outbound bandwidth rate for outbound bandwidth above 5 GB. A web-site running in shared mode also now supports the ability to map multiple custom DNS domain names, using both CNAMEs and A-records, to it.  The new A-record support we are introducing with today’s release provides the ability for you to support “naked domains” with your web-sites (e.g. http://microsoft.com in addition to http://www.microsoft.com).  We will also in the future enable SNI based SSL as a built-in feature with shared mode web-sites (this functionality isn’t supported with today’s release – but will be coming later this year to both the shared and reserved tiers). You pay for a shared mode web-site using the standard “pay as you go” model that we support with other features of Windows Azure (meaning no up-front costs, and you pay only for the hours that the feature is enabled).  A web-site running in shared mode costs only 1.3 cents/hr during the preview (so on average $9.36/month). Reserved Instance Mode In addition to running sites in shared mode, we also support scaling them to run within a reserved instance mode.  When running in reserved instance mode your sites are guaranteed to run isolated within your own Small, Medium or Large VM (meaning no other customers run within it).  You can run any number of web-sites within a VM, and there are no quotas on CPU or memory limits. You can run your sites using either a single reserved instance VM, or scale up to have multiple instances of them (e.g. 2 medium sized VMs, etc).  Scaling up or down is easy – just select the “reserved” instance VM within the “scale” tab of the Windows Azure Portal, choose the VM size you want, the number of instances of it you want to run, and then click save.  Changes take effect in seconds: Unlike shared mode, there is no per-site cost when running in reserved mode.  Instead you pay only for the reserved instance VMs you use – and you can run any number of web-sites you want within them at no extra cost (e.g. you could run a single site within a reserved instance VM or 100 web-sites within it for the same cost).  Reserved instance VMs start at 8 cents/hr for a small reserved VM.  Elastic Scale-up/down Windows Azure Web Sites allows you to scale-up or down your capacity within seconds.  This allows you to deploy a site using the shared mode option to begin with, and then dynamically scale up to the reserved mode option only when you need to – without you having to change any code or redeploy your application. If your site traffic starts to drop off, you can scale back down the number of reserved instances you are using, or scale down to the shared mode tier – all within seconds and without having to change code, redeploy, or adjust DNS mappings.  You can also use the “Dashboard” view within the Windows Azure Portal to easily monitor your site’s load in real-time (it shows not only requests/sec and bandwidth but also stats like CPU and memory usage). Because of Windows Azure’s “pay as you go” pricing model, you only pay for the compute capacity you use in a given hour.  So if your site is running most of the month in shared mode (at 1.3 cents/hr), but there is a weekend when it gets really popular and you decide to scale it up into reserved mode to have it run in your own dedicated VM (at 8 cents/hr), you only have to pay the additional pennies/hr for the hours it is running in the reserved mode.  There is no upfront cost you need to pay to enable this, and once you scale back down to shared mode you return to the 1.3 cents/hr rate.  This makes it super flexible and cost effective. Improved Custom Domain Support Web sites running in either “shared” or “reserved” mode support the ability to associate custom host names to them (e.g. www.mysitename.com).  You can associate multiple custom domains to each Windows Azure Web Site.  With today’s release we are introducing support for A-Records (a big ask by many users). With the A-Record support, you can now associate ‘naked’ domains to your Windows Azure Web Sites – meaning instead of having to use www.mysitename.com you can instead just have mysitename.com (with no sub-name prefix).  Because you can map multiple domains to a single site, you can optionally enable both a www and naked domain for a site (and then use a URL rewrite rule/redirect to avoid SEO problems). We’ve also enhanced the UI for managing custom domains within the Windows Azure Portal as part of today’s release.  Clicking the “Manage Domains” button in the tray at the bottom of the portal now brings up custom UI that makes it easy to manage/configure them: As part of this update we’ve also made it significantly smoother/easier to validate ownership of custom domains, and made it easier to switch existing sites/domains to Windows Azure Web Sites with no downtime. Continuous Deployment Support with Git and CodePlex or GitHub One of the more popular features we released earlier this summer was support for publishing web sites directly to Windows Azure using source control systems like TFS and Git.  This provides a really powerful way to manage your application deployments using source control.  It is really easy to enable this from a website’s dashboard page: The TFS option we shipped earlier this summer provides a very rich continuous deployment solution that enables you to automate builds and run unit tests every time you check in your web-site, and then if they are successful automatically publish to Azure. With today’s release we are expanding our Git support to also enable continuous deployment scenarios and integrate with projects hosted on CodePlex and GitHub.  This support is enabled with all web-sites (including those using the “free” scaling mode). Starting today, when you choose the “Set up Git publishing” link on a website’s “Dashboard” page you’ll see two additional options show up when Git based publishing is enabled for the web-site: You can click on either the “Deploy from my CodePlex project” link or “Deploy from my GitHub project” link to walkthrough a simple workflow to configure a connection between your website and a source repository you host on CodePlex or GitHub.  Once this connection is established, CodePlex or GitHub will automatically notify Windows Azure every time a checkin occurs.  This will then cause Windows Azure to pull the source and compile/deploy the new version of your app automatically.  The below two videos walkthrough how easy this is to enable this workflow and deploy both an initial app and then make a change to it: Enabling Continuous Deployment with Windows Azure Websites and CodePlex (2 minutes) Enabling Continuous Deployment with Windows Azure Websites and GitHub (2 minutes) This approach enables a really clean continuous deployment workflow, and makes it much easier to support a team development environment using Git: Note: today’s release supports establishing connections with public GitHub/CodePlex repositories.  Support for private repositories will be enabled in a few weeks. Support for multiple branches Previously, we only supported deploying from the git ‘master’ branch.  Often, though, developers want to deploy from alternate branches (e.g. a staging or future branch). This is now a supported scenario – both with standalone git based projects, as well as ones linked to CodePlex or GitHub.  This enables a variety of useful scenarios.  For example, you can now have two web-sites - a “live” and “staging” version – both linked to the same repository on CodePlex or GitHub.  You can configure one of the web-sites to always pull whatever is in the master branch, and the other to pull what is in the staging branch.  This enables a really clean way to enable final testing of your site before it goes live. This 1 minute video demonstrates how to configure which branch to use with a web-site. Summary The above features are all now live in production and available to use immediately.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using them today.  Visit the Windows Azure Developer Center to learn more about how to build apps with it. We’ll have even more new features and enhancements coming in the weeks ahead – including support for the recent Windows Server 2012 and .NET 4.5 releases (we will enable new web and worker role images with Windows Server 2012 and .NET 4.5 next month).  Keep an eye out on my blog for details as these new features become available. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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• HTG Explains: Just How Bad Are Android Tablet Apps?

  - by Chris Hoffman

  Apple loves to criticize the state of Android tablet apps when pushing its own iPad tablets. But just how bad is the Android tablet app situation? Should you avoid Android tablets like the Nexus 7 because of the apps? It’s clear that Apple’s iPad is way ahead when it comes to the sheer quantity of tablet-optimized apps. It’s also clear that some popular apps — particularly touch-optimized games — only show up on iPad. But that’s not the whole story. The Basics First, let’s get an idea of the basic stuff that will work well for you on Android. An excellent web browser. Chrome has struggled with performance on Android, but hits its stride on the Nexus 7 (2013). Great, tablet-optimized apps for all of Google’s services, from YouTube to Gmail and Google Maps. Everything you need for reading, from Amazon’s Kindle app for eBooks, Flipboard and Feedly for new articles from websites, and other services like the popular Pocket read-it-later service. Apps for most popular media services, from Netflix, Hulu, and YouTube for videos to Pandora, Spotify, and Rdio for music. A few things aren’t available — you won’t find Apple’s iTunes and Amazon still doesn’t offer an Amazon Instant Video app for Android, while they do for iPad and even their own Android-based Kindle Fire devices. Android has very good app coverage when it comes to consuming content, whether you’re reading websites and ebooks or watching videos and listening to music. You can play almost any Android smartphone game, too. For content consumption, Android is better than something like Windows 8, which lacks apps for Google services like YouTube and still doesn’t have apps for popular media services like Spotify and Rdio. How Android Scales Smartphone Apps Let’s look at how Android scales smartphone apps. Now, bear with us here — we know “scaling” is a dirty word considering how poorly Apple’s iPad scales iPhone apps, but it’s not as bad on Android. When an iPad runs an iPhone app, it simply doubles the pixels and effectively zooms in. For example, if you had  Twitter app with five tweets visible at once on an iPhone and ran the same app on an iPad, the iPad would simply “zoom in” and enlarge the same screen — you’d still see five tweets, but each tweet would appear larger. This is why developers create optimized iPad apps with their own interfaces. It’s especially important on Apple’s iOS. Android devices come in all shapes and sizes, so Android apps have a smarter, more intelligent way to adapt to different screen sizes. Let’s say you have a Twitter app designed for smartphones and it only shows five tweets at once when run on a phone. If you ran the same app on a tablet, you wouldn’t see the same five tweets — you’d see ten or more tweets. Rather than simply zooming in, the app can show more content at the same time on a tablet, even if it was never optimized for tablet-size screens. While apps designed for smartphones aren’t generally ideal, they adapt much better on Android than they do on an iPad. This is particularly true when it comes to games. You’re capable of playing almost any Android smartphone game on an Android tablet, and games generally adapt very well to the larger screen. This gives you access to a huge catalog of games. It’s a great option to have, especially when you look at Microsoft’s Window 8 and consider how much better the touch-based app and game selection would be if Microsoft allowed its users to run Windows Phone games on Windows 8. 7-inch vs 10-inch Tablets The Twitter example above wasn’t just an example. The official Twitter app for Android still doesn’t have a tablet-optimized interface, so this is the sort of situation you’d have to deal with on an Android tablet. On the popular Nexus 7, Twitter is an example of a smartphone app that actually works fairly well — in portrait mode, you can see many more tweets on screen at the same time and none of the space really feels all that wasted. This is important to consider — smartphone apps like Twitter often scale quite well to 7-inch screens because a 7-inch screen is much closer in form factor to a smartphone than a 10-inch screen is. When you begin to look at 10-inch Android tablets that are the same size as an iPad, the situation changes. While the Twitter app works well enough on a Nexus 7, it looks horrible on a Nexus 10 or other 10-inch tablet. Running many smartphone-designed apps — possible with the exception of games — on a 10-inch tablet is a frustrating, poor experience. There’s much more white, empty space in the interface. It feels like you’re using a smartphone app on a large screen, and what’s the point of that? A tablet-optimized Twitter app for Android is finally on its way, but this same situation will repeat with many other types of apps. For example, Facebook doesn’t offer a tablet-optimized interface, but it’s okay on a Nexus 7 anyway. On a 10-inch screen, it probably wouldn’t be anywhere near as nice an experience. It goes without saying that Facebook and Twitter both offer iPad apps with interfaces designed for a tablet-size screen. Here’s another problematic app — the official Yelp app for Android. Even just using it on a 7-inch Nexus 7 will be a poor experience, while it would be much worse on a larger 10-inch tablet app. Now, it’s true that many — maybe even most — of the popular apps you might want to run today are optimized for Android tablets. But, when you look at the situation when it comes to popular apps like Twitter, Facebook, and Yelp, it’s clear Android is still behind in a meaningful way. Price Let’s be honest. The thing that really makes Android tablets compelling — and the only reason Android tablets started seeing real traction after years of almost complete dominance by Apple’s iPads — is that Android tablets are available for so much cheaper than iPads. Google’s latest Nexus 7 (2013) is available for only $230. Apple’s non-retina iPad Mini is available at $300, which is already $70 more. In spite of that, the iPad Mini has much older, slower internals and a much lower resolution screen. It’s not as nice to look at when it comes to reading or watching movies, and the iPad Mini reportedly struggles to run Apple’s latest iOS 7. In contrast, the new Nexus 7 has a very high resolution screen, speedy internals, and runs Android very well with little-to-no lag in real use. We haven’t had any problems with it, unlike all the problems we unfortunately encountered with the first Nexus 7. For a really comparable experience to the current Nexus 7, you’d want to get one of Apple’s new retina iPad Minis. That would cost you $400, another $170 over the Nexus 7. In fact, it’s possible to regularly find sales on the Nexus 7, so if you waited you could get it for just $200 — half the price of the iPad mini with a comparable screen and internals. (In fairness, the iPad certainly has better hardware — but you won’t feel if it you’re just using your tablet to browse the web, watch videos, and do other typical tablet things.) This makes a tablet like the popular Nexus 7 a very good option for budget-conscious users who just want a high-quality device they can use to browse the web, watch videos, play games, and generally do light computing. There’s a reason we’re focusing on the Nexus 7 here. The combination of price and size brings it to a very good place. It’s awfully cheap for the high-quality experience you get, and the 7-inch screen means that even the non-tablet-optimized apps you may stumble across will often work fairly well. On the other hand, more expensive 10-inch Android tablets are still a tougher sell. For $400-$500, you’re getting awfully close to Apple’s full-size iPad price range and Android tablets don’t have as good an app ecosystem as an iPad. It’s hard to recommend an expensive, 10-inch Android tablet over a full-size iPad to average users. In summary, the Android app tablet app situation is nowhere near as bad as it was a few years ago. The success of the Nexus 7 proves that Android tablets can be compelling experiences, and there are a wide variety of strong apps. That said, more expensive 10-inch Android tablets that compete directly with the full-size iPad on price still don’t make much sense for most people.  Unless you have a specific reason for preferring an Android tablet, it’s tough not to recommend an iPad if you’re looking at spending $400+ on a 10-inch tablet. Image Credit: Christian Ghanime on Flickr, Christian Ghanime on Flickr     

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• Metro: Dynamically Switching Templates with a WinJS ListView

  - by Stephen.Walther

  Imagine that you want to display a list of products using the WinJS ListView control. Imagine, furthermore, that you want to use different templates to display different products. In particular, when a product is on sale, you want to display the product using a special “On Sale” template. In this blog entry, I explain how you can switch templates dynamically when displaying items with a ListView control. In other words, you learn how to use more than one template when displaying items with a ListView control. Creating the Data Source Let’s start by creating the data source for the ListView. Nothing special here – our data source is a list of products. Two of the products, Oranges and Apples, are on sale. (function () { "use strict"; var products = new WinJS.Binding.List([ { name: "Milk", price: 2.44 }, { name: "Oranges", price: 1.99, onSale: true }, { name: "Wine", price: 8.55 }, { name: "Apples", price: 2.44, onSale: true }, { name: "Steak", price: 1.99 }, { name: "Eggs", price: 2.44 }, { name: "Mushrooms", price: 1.99 }, { name: "Yogurt", price: 2.44 }, { name: "Soup", price: 1.99 }, { name: "Cereal", price: 2.44 }, { name: "Pepsi", price: 1.99 } ]); WinJS.Namespace.define("ListViewDemos", { products: products }); })(); The file above is saved with the name products.js and referenced by the default.html page described below. Declaring the Templates and ListView Control Next, we need to declare the ListView control and the two Template controls which we will use to display template items. The markup below appears in the default.html file: <!-- Templates --> <div id="productItemTemplate" data-win-control="WinJS.Binding.Template"> <div class="product"> <span data-win-bind="innerText:name"></span> <span data-win-bind="innerText:price"></span> </div> </div> <div id="productOnSaleTemplate" data-win-control="WinJS.Binding.Template"> <div class="product onSale"> <span data-win-bind="innerText:name"></span> <span data-win-bind="innerText:price"></span> (On Sale!) </div> </div> <!-- ListView --> <div id="productsListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: ListViewDemos.products.dataSource, layout: { type: WinJS.UI.ListLayout } }"> </div> In the markup above, two Template controls are declared. The first template is used when rendering a normal product and the second template is used when rendering a product which is on sale. The second template, unlike the first template, includes the text “(On Sale!)”. The ListView control is bound to the data source which we created in the previous section. The ListView itemDataSource property is set to the value ListViewDemos.products.dataSource. Notice that we do not set the ListView itemTemplate property. We set this property in the default.js file. Switching Between Templates All of the magic happens in the default.js file. The default.js file contains the JavaScript code used to switch templates dynamically. Here’s the entire contents of the default.js file: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll().then(function () { var productsListView = document.getElementById("productsListView"); productsListView.winControl.itemTemplate = itemTemplateFunction; });; } }; function itemTemplateFunction(itemPromise) { return itemPromise.then(function (item) { // Select either normal product template or on sale template var itemTemplate = document.getElementById("productItemTemplate"); if (item.data.onSale) { itemTemplate = document.getElementById("productOnSaleTemplate"); }; // Render selected template to DIV container var container = document.createElement("div"); itemTemplate.winControl.render(item.data, container); return container; }); } app.start(); })(); In the code above, a function is assigned to the ListView itemTemplate property with the following line of code: productsListView.winControl.itemTemplate = itemTemplateFunction;   The itemTemplateFunction returns a DOM element which is used for the template item. Depending on the value of the product onSale property, the DOM element is generated from either the productItemTemplate or the productOnSaleTemplate template. Using Binding Converters instead of Multiple Templates In the previous sections, I explained how you can use different templates to render normal products and on sale products. There is an alternative approach to displaying different markup for normal products and on sale products. Instead of creating two templates, you can create a single template which contains separate DIV elements for a normal product and an on sale product. The following default.html file contains a single item template and a ListView control bound to the template. <!-- Template --> <div id="productItemTemplate" data-win-control="WinJS.Binding.Template"> <div class="product" data-win-bind="style.display: onSale ListViewDemos.displayNormalProduct"> <span data-win-bind="innerText:name"></span> <span data-win-bind="innerText:price"></span> </div> <div class="product onSale" data-win-bind="style.display: onSale ListViewDemos.displayOnSaleProduct"> <span data-win-bind="innerText:name"></span> <span data-win-bind="innerText:price"></span> (On Sale!) </div> </div> <!-- ListView --> <div id="productsListView" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: ListViewDemos.products.dataSource, itemTemplate: select('#productItemTemplate'), layout: { type: WinJS.UI.ListLayout } }"> </div> The first DIV element is used to render a normal product: <div class="product" data-win-bind="style.display: onSale ListViewDemos.displayNormalProduct"> <span data-win-bind="innerText:name"></span> <span data-win-bind="innerText:price"></span> </div> The second DIV element is used to render an “on sale” product: <div class="product onSale" data-win-bind="style.display: onSale ListViewDemos.displayOnSaleProduct"> <span data-win-bind="innerText:name"></span> <span data-win-bind="innerText:price"></span> (On Sale!) </div> Notice that both templates include a data-win-bind attribute. These data-win-bind attributes are used to show the “normal” template when a product is not on sale and show the “on sale” template when a product is on sale. These attributes set the Cascading Style Sheet display attribute to either “none” or “block”. The data-win-bind attributes take advantage of binding converters. The binding converters are defined in the default.js file: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll(); } }; WinJS.Namespace.define("ListViewDemos", { displayNormalProduct: WinJS.Binding.converter(function (onSale) { return onSale ? "none" : "block"; }), displayOnSaleProduct: WinJS.Binding.converter(function (onSale) { return onSale ? "block" : "none"; }) }); app.start(); })(); The ListViewDemos.displayNormalProduct binding converter converts the value true or false to the value “none” or “block”. The ListViewDemos.displayOnSaleProduct binding converter does the opposite; it converts the value true or false to the value “block” or “none” (Sadly, you cannot simply place a NOT operator before the onSale property in the binding expression – you need to create both converters). The end result is that you can display different markup depending on the value of the product onSale property. Either the contents of the first or second DIV element are displayed: Summary In this blog entry, I’ve explored two approaches to displaying different markup in a ListView depending on the value of a data item property. The bulk of this blog entry was devoted to explaining how you can assign a function to the ListView itemTemplate property which returns different templates. We created both a productItemTemplate and productOnSaleTemplate and displayed both templates with the same ListView control. We also discussed how you can create a single template and display different markup by using binding converters. The binding converters are used to set a DIV element’s display property to either “none” or “block”. We created a binding converter which displays normal products and a binding converter which displays “on sale” products.

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• Building LMMS: "Configuring incomplete, errors occurred!"

  - by fridojet

  I tried to build Linux MultiMedia studio from the source of the SourceForge git:// repository under Ubuntu 12.04 LTS 32b: git clone git://lmms.git.sourceforge.net/gitroot/lmms/lmms cd lmms git checkout First I tried to install all the required libraries and then I cmaked. - That's what happened on cmake (errors occurred!): [DIR]lmms/build$ cmake .. -- The C compiler identification is GNU -- The CXX compiler identification is GNU -- Check for working C compiler: /usr/bin/gcc -- Check for working C compiler: /usr/bin/gcc -- works -- Detecting C compiler ABI info -- Detecting C compiler ABI info - done -- Check for working CXX compiler: /usr/bin/c++ -- Check for working CXX compiler: /usr/bin/c++ -- works -- Detecting CXX compiler ABI info -- Detecting CXX compiler ABI info - done PROCESSOR: i686 Machine: i686-linux-gnu -- Target host is 32 bit -- Looking for include files LMMS_HAVE_STDINT_H -- Looking for include files LMMS_HAVE_STDINT_H - found -- Looking for include files LMMS_HAVE_STDBOOL_H -- Looking for include files LMMS_HAVE_STDBOOL_H - found -- Looking for include files LMMS_HAVE_STDLIB_H -- Looking for include files LMMS_HAVE_STDLIB_H - found -- Looking for include files LMMS_HAVE_PTHREAD_H -- Looking for include files LMMS_HAVE_PTHREAD_H - found -- Looking for include files LMMS_HAVE_SEMAPHORE_H -- Looking for include files LMMS_HAVE_SEMAPHORE_H - found -- Looking for include files LMMS_HAVE_UNISTD_H -- Looking for include files LMMS_HAVE_UNISTD_H - found -- Looking for include files LMMS_HAVE_SYS_TYPES_H -- Looking for include files LMMS_HAVE_SYS_TYPES_H - found -- Looking for include files LMMS_HAVE_SYS_IPC_H -- Looking for include files LMMS_HAVE_SYS_IPC_H - found -- Looking for include files LMMS_HAVE_SYS_SHM_H -- Looking for include files LMMS_HAVE_SYS_SHM_H - found -- Looking for include files LMMS_HAVE_SYS_TIME_H -- Looking for include files LMMS_HAVE_SYS_TIME_H - found -- Looking for include files LMMS_HAVE_SYS_WAIT_H -- Looking for include files LMMS_HAVE_SYS_WAIT_H - found -- Looking for include files LMMS_HAVE_SYS_SELECT_H -- Looking for include files LMMS_HAVE_SYS_SELECT_H - found -- Looking for include files LMMS_HAVE_STDARG_H -- Looking for include files LMMS_HAVE_STDARG_H - found -- Looking for include files LMMS_HAVE_SIGNAL_H -- Looking for include files LMMS_HAVE_SIGNAL_H - found -- Looking for include files LMMS_HAVE_SCHED_H -- Looking for include files LMMS_HAVE_SCHED_H - found -- Looking for include files LMMS_HAVE_SYS_SOUNDCARD_H -- Looking for include files LMMS_HAVE_SYS_SOUNDCARD_H - found -- Looking for include files LMMS_HAVE_SOUNDCARD_H -- Looking for include files LMMS_HAVE_SOUNDCARD_H - not found. -- Looking for include files LMMS_HAVE_FCNTL_H -- Looking for include files LMMS_HAVE_FCNTL_H - found -- Looking for include files LMMS_HAVE_SYS_IOCTL_H -- Looking for include files LMMS_HAVE_SYS_IOCTL_H - found -- Looking for include files LMMS_HAVE_CTYPE_H -- Looking for include files LMMS_HAVE_CTYPE_H - found -- Looking for include files LMMS_HAVE_STRING_H -- Looking for include files LMMS_HAVE_STRING_H - found -- Looking for include files LMMS_HAVE_PROCESS_H -- Looking for include files LMMS_HAVE_PROCESS_H - not found. -- Looking for include files LMMS_HAVE_LOCALE_H -- Looking for include files LMMS_HAVE_LOCALE_H - found -- Looking for Q_WS_X11 -- Looking for Q_WS_X11 - found -- Looking for Q_WS_WIN -- Looking for Q_WS_WIN - not found. -- Looking for Q_WS_QWS -- Looking for Q_WS_QWS - not found. -- Looking for Q_WS_MAC -- Looking for Q_WS_MAC - not found. -- Found Qt4: /usr/bin/qmake (found suitable version "4.8.1", required is "4.6.0;COMPONENTS;QtCore;QtGui;QtXml;QtNetwork") -- Found Qt translations in /usr/share/qt4/translations -- checking for module 'sndfile>=1.0.11' -- found sndfile, version 1.0.25 -- Looking for include files CMAKE_HAVE_PTHREAD_H -- Looking for include files CMAKE_HAVE_PTHREAD_H - found -- Looking for pthread_create in pthreads -- Looking for pthread_create in pthreads - not found -- Looking for pthread_create in pthread -- Looking for pthread_create in pthread - found -- Found Threads: TRUE -- Found libzip: /usr/lib/libzip.so -- Found libflac++: /usr/lib/i386-linux-gnu/libFLAC.so;/usr/lib/i386-linux-gnu/libFLAC++.so -- Found STK: /usr/lib/i386-linux-gnu/libstk.so -- checking for module 'portaudio-2.0' -- found portaudio-2.0, version 19 -- Found Portaudio: portaudio;asound;m;pthread -- checking for module 'libpulse' -- found libpulse, version 1.1 -- Found PulseAudio Simple: /usr/lib/i386-linux-gnu/libpulse.so -- Looking for vorbis_bitrate_addblock in vorbis -- Looking for vorbis_bitrate_addblock in vorbis - found -- Found OggVorbis: /usr/lib/i386-linux-gnu/libogg.so;/usr/lib/i386-linux-gnu/libvorbis.so;/usr/lib/i386-linux-gnu/libvorbisfile.so;/usr/lib/i386-linux-gnu/libvorbisenc.so -- Looking for snd_seq_create_simple_port in asound -- Looking for snd_seq_create_simple_port in asound - found -- Found ALSA: /usr/lib/i386-linux-gnu/libasound.so -- Looking for include files LMMS_HAVE_MACHINE_SOUNDCARD_H -- Looking for include files LMMS_HAVE_MACHINE_SOUNDCARD_H - not found. -- Looking for include files LMMS_HAVE_LINUX_AWE_VOICE_H -- Looking for include files LMMS_HAVE_LINUX_AWE_VOICE_H - not found. -- Looking for include files LMMS_HAVE_AWE_VOICE_H -- Looking for include files LMMS_HAVE_AWE_VOICE_H - not found. -- Looking for include files LMMS_HAVE__USR_SRC_SYS_I386_ISA_SOUND_AWE_VOICE_H -- Looking for include files LMMS_HAVE__USR_SRC_SYS_I386_ISA_SOUND_AWE_VOICE_H - not found. -- Looking for include files LMMS_HAVE__USR_SRC_SYS_GNU_I386_ISA_SOUND_AWE_VOICE_H -- Looking for include files LMMS_HAVE__USR_SRC_SYS_GNU_I386_ISA_SOUND_AWE_VOICE_H - not found. -- Looking for C++ include sys/asoundlib.h -- Looking for C++ include sys/asoundlib.h - found -- Looking for C++ include alsa/asoundlib.h -- Looking for C++ include alsa/asoundlib.h - found -- Looking for snd_pcm_resume in asound -- Looking for snd_pcm_resume in asound - found -- checking for module 'jack>=0.77' -- found jack, version 0.121.2 -- checking for module 'fftw3f>=3.0.0' -- package 'fftw3f>=3.0.0' not found CMake Error at /usr/share/cmake-2.8/Modules/FindPkgConfig.cmake:266 (message): A required package was not found Call Stack (most recent call first): /usr/share/cmake-2.8/Modules/FindPkgConfig.cmake:320 (_pkg_check_modules_internal) CMakeLists.txt:309 (PKG_CHECK_MODULES) -- checking for module 'fluidsynth>=1.0.7' -- found fluidsynth, version 1.1.5 -- Looking for include files LMMS_HAVE_LV2CORE -- Looking for include files LMMS_HAVE_LV2CORE - found -- Looking for include files LMMS_HAVE_SLV2_SCALEPOINTS_H -- Looking for include files LMMS_HAVE_SLV2_SCALEPOINTS_H - not found. -- Looking for slv2_world_new in slv2 -- Looking for slv2_world_new in slv2 - found -- Looking for librdf_new_world in rdf -- Looking for librdf_new_world in rdf - found -- Looking for wine_init in wine -- Looking for wine_init in wine - found -- Looking for C++ include windows.h -- Looking for C++ include windows.h - found -- checking for module 'samplerate>=0.1.7' -- package 'samplerate>=0.1.7' not found -- Performing Test HAVE_LRINT -- Performing Test HAVE_LRINT - Success -- Performing Test HAVE_LRINTF -- Performing Test HAVE_LRINTF - Success -- Performing Test CPU_CLIPS_POSITIVE -- Performing Test CPU_CLIPS_POSITIVE - Failed -- Performing Test CPU_CLIPS_NEGATIVE -- Performing Test CPU_CLIPS_NEGATIVE - Success -- Looking for XOpenDisplay in /usr/lib/i386-linux-gnu/libX11.so;/usr/lib/i386-linux-gnu/libXext.so -- Looking for XOpenDisplay in /usr/lib/i386-linux-gnu/libX11.so;/usr/lib/i386-linux-gnu/libXext.so - found -- Looking for gethostbyname -- Looking for gethostbyname - found -- Looking for connect -- Looking for connect - found -- Looking for remove -- Looking for remove - found -- Looking for shmat -- Looking for shmat - found -- Looking for IceConnectionNumber in ICE -- Looking for IceConnectionNumber in ICE - found -- Found X11: /usr/lib/i386-linux-gnu/libX11.so -- Found Freetype: /usr/lib/i386-linux-gnu/libfreetype.so Installation Summary -------------------- * Install Directory : /usr/local * Use system's libsamplerate : Supported audio interfaces -------------------------- * ALSA : OK * JACK : OK * OSS : OK * PortAudio : OK * PulseAudio : OK * SDL : OK Supported MIDI interfaces ------------------------- * ALSA : OK * OSS : OK * WinMM : <not supported on this platform> Supported file formats for project export ----------------------------------------- * WAVE : OK * OGG/VORBIS : OK * FLAC : OK Optional plugins ---------------- * SoundFont2 player : OK * Stk Mallets : OK * VST-instrument hoster : OK * VST-effect hoster : OK * LV2 hoster : OK * CALF LADSPA plugins : OK * CAPS LADSPA plugins : OK * CMT LADSPA plugins : OK * TAP LADSPA plugins : OK * SWH LADSPA plugins : OK * FL .zip import : OK ----------------------------------------------------------------- IMPORTANT: after installing missing packages, remove CMakeCache.txt before running cmake again! ----------------------------------------------------------------- -- Configuring incomplete, errors occurred! Here are some parts the contents of my lmms/build/CMakeCache.txt file: # This is the CMakeCache file. # For build in directory: /home/jk/Downloads/lmms-git/lmms/build # It was generated by CMake: /usr/bin/cmake # You can edit this file to change values found and used by cmake. # If you do not want to change any of the values, simply exit the editor. # If you do want to change a value, simply edit, save, and exit the editor. # The syntax for the file is as follows: # KEY:TYPE=VALUE # KEY is the name of a variable in the cache. # TYPE is a hint to GUI's for the type of VALUE, DO NOT EDIT TYPE!. # VALUE is the current value for the KEY. ######################## # EXTERNAL cache entries ######################## //Path to a file. ALSA_INCLUDES:PATH=/usr/include //Path to a library. ASOUND_LIBRARY:FILEPATH=/usr/lib/i386-linux-gnu/libasound.so //Path to a program. CMAKE_AR:FILEPATH=/usr/bin/ar //Choose the type of build, options are: None(CMAKE_CXX_FLAGS or // CMAKE_C_FLAGS used) Debug Release RelWithDebInfo MinSizeRel. CMAKE_BUILD_TYPE:STRING= //Enable/Disable color output during build. CMAKE_COLOR_MAKEFILE:BOOL=ON //CXX compiler. CMAKE_CXX_COMPILER:FILEPATH=/usr/bin/c++ //Flags used by the compiler during all build types. CMAKE_CXX_FLAGS:STRING= //Flags used by the compiler during debug builds. CMAKE_CXX_FLAGS_DEBUG:STRING=-g //Flags used by the compiler during release minsize builds. CMAKE_CXX_FLAGS_MINSIZEREL:STRING=-Os -DNDEBUG //Flags used by the compiler during release builds (/MD /Ob1 /Oi // /Ot /Oy /Gs will produce slightly less optimized but smaller // files). CMAKE_CXX_FLAGS_RELEASE:STRING=-O3 -DNDEBUG //Flags used by the compiler during Release with Debug Info builds. CMAKE_CXX_FLAGS_RELWITHDEBINFO:STRING=-O2 -g //C compiler. CMAKE_C_COMPILER:FILEPATH=/usr/bin/gcc //Flags used by the compiler during all build types. CMAKE_C_FLAGS:STRING= //Flags used by the compiler during debug builds. CMAKE_C_FLAGS_DEBUG:STRING=-g //Flags used by the compiler during release minsize builds. CMAKE_C_FLAGS_MINSIZEREL:STRING=-Os -DNDEBUG //Flags used by the compiler during release builds (/MD /Ob1 /Oi // /Ot /Oy /Gs will produce slightly less optimized but smaller // files). CMAKE_C_FLAGS_RELEASE:STRING=-O3 -DNDEBUG //Flags used by the compiler during Release with Debug Info builds. CMAKE_C_FLAGS_RELWITHDEBINFO:STRING=-O2 -g //Flags used by the linker. CMAKE_EXE_LINKER_FLAGS:STRING=' ' //Flags used by the linker during debug builds. CMAKE_EXE_LINKER_FLAGS_DEBUG:STRING= //Flags used by the linker during release minsize builds. CMAKE_EXE_LINKER_FLAGS_MINSIZEREL:STRING= //Flags used by the linker during release builds. CMAKE_EXE_LINKER_FLAGS_RELEASE:STRING= //Flags used by the linker during Release with Debug Info builds. CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO:STRING= //Enable/Disable output of compile commands during generation. CMAKE_EXPORT_COMPILE_COMMANDS:BOOL=OFF //Install path prefix, prepended onto install directories. CMAKE_INSTALL_PREFIX:PATH=/usr/local //Path to a program. CMAKE_LINKER:FILEPATH=/usr/bin/ld //Path to a program. CMAKE_MAKE_PROGRAM:FILEPATH=/usr/bin/make //Flags used by the linker during the creation of modules. CMAKE_MODULE_LINKER_FLAGS:STRING=' ' //Flags used by the linker during debug builds. CMAKE_MODULE_LINKER_FLAGS_DEBUG:STRING= //Flags used by the linker during release minsize builds. CMAKE_MODULE_LINKER_FLAGS_MINSIZEREL:STRING= //Flags used by the linker during release builds. CMAKE_MODULE_LINKER_FLAGS_RELEASE:STRING= //Flags used by the linker during Release with Debug Info builds. CMAKE_MODULE_LINKER_FLAGS_RELWITHDEBINFO:STRING= ==[...]== That's a list of the contents of my lmms/build folder: [DIR]lmms/build$ dir CMakeCache.txt CPackSourceConfig.cmake lmmsconfig.h plugins CMakeFiles data lmms.rc CPackConfig.cmake include lmmsversion.h My Question: It just tells me that that "errors" occurred, but I can't see any error message. It seems like everything went fine. - So: Any idea what the problem could be? - Thanks.

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• C#/.NET Little Wonders: Use Cast() and TypeOf() to Change Sequence Type

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. We’ve seen how the Select() extension method lets you project a sequence from one type to a new type which is handy for getting just parts of items, or building new items.  But what happens when the items in the sequence are already the type you want, but the sequence itself is typed to an interface or super-type instead of the sub-type you need? For example, you may have a sequence of Rectangle stored in an IEnumerable<Shape> and want to consider it an IEnumerable<Rectangle> sequence instead.  Today we’ll look at two handy extension methods, Cast<TResult>() and OfType<TResult>() which help you with this task. Cast<TResult>() – Attempt to cast all items to type TResult So, the first thing we can do would be to attempt to create a sequence of TResult from every item in the source sequence.  Typically we’d do this if we had an IEnumerable<T> where we knew that every item was actually a TResult where TResult inherits/implements T. For example, assume the typical Shape example classes: 1: // abstract base class 2: public abstract class Shape { } 3:  4: // a basic rectangle 5: public class Rectangle : Shape 6: { 7: public int Widtgh { get; set; } 8: public int Height { get; set; } 9: } And let’s assume we have a sequence of Shape where every Shape is a Rectangle… 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: // ... 6: }; To get the sequence of Shape as a sequence of Rectangle, of course, we could use a Select() clause, such as: 1: // select each Shape, cast it to Rectangle 2: var rectangles = shapes 3: .Select(s => (Rectangle)s) 4: .ToList(); But that’s a bit verbose, and fortunately there is already a facility built in and ready to use in the form of the Cast<TResult>() extension method: 1: // cast each item to Rectangle and store in a List<Rectangle> 2: var rectangles = shapes 3: .Cast<Rectangle>() 4: .ToList(); However, we should note that if anything in the list cannot be cast to a Rectangle, you will get an InvalidCastException thrown at runtime.  Thus, if our Shape sequence had a Circle in it, the call to Cast<Rectangle>() would have failed.  As such, you should only do this when you are reasonably sure of what the sequence actually contains (or are willing to handle an exception if you’re wrong). Another handy use of Cast<TResult>() is using it to convert an IEnumerable to an IEnumerable<T>.  If you look at the signature, you’ll see that the Cast<TResult>() extension method actually extends the older, object-based IEnumerable interface instead of the newer, generic IEnumerable<T>.  This is your gateway method for being able to use LINQ on older, non-generic sequences.  For example, consider the following: 1: // the older, non-generic collections are sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 13 }, 5: new Rectangle { Width = 10, Height = 20 }, 6: // ... 7: }; Since this is an older, object based collection, we cannot use the LINQ extension methods on it directly.  For example, if I wanted to query the Shape sequence for only those Rectangles whose Width is > 5, I can’t do this: 1: // compiler error, Where() operates on IEnumerable<T>, not IEnumerable 2: var bigRectangles = shapes.Where(r => r.Width > 5); However, I can use Cast<Rectangle>() to treat my ArrayList as an IEnumerable<Rectangle> and then do the query! 1: // ah, that’s better! 2: var bigRectangles = shapes.Cast<Rectangle>().Where(r => r.Width > 5); Or, if you prefer, in LINQ query expression syntax: 1: var bigRectangles = from s in shapes.Cast<Rectangle>() 2: where s.Width > 5 3: select s; One quick warning: Cast<TResult>() only attempts to cast, it won’t perform a cast conversion.  That is, consider this: 1: var intList = new List<int> { 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 }; 2:  3: // casting ints to longs, this should work, right? 4: var asLong = intList.Cast<long>().ToList(); Will the code above work?  No, you’ll get a InvalidCastException. Remember that Cast<TResult>() is an extension of IEnumerable, thus it is a sequence of object, which means that it will box every int as an object as it enumerates over it, and there is no cast conversion from object to long, and thus the cast fails.  In other words, a cast from int to long will succeed because there is a conversion from int to long.  But a cast from int to object to long will not, because you can only unbox an item by casting it to its exact type. For more information on why cast-converting boxed values doesn’t work, see this post on The Dangers of Casting Boxed Values (here). OfType<TResult>() – Filter sequence to only items of type TResult So, we’ve seen how we can use Cast<TResult>() to change the type of our sequence, when we expect all the items of the sequence to be of a specific type.  But what do we do when a sequence contains many different types, and we are only concerned with a subset of a given type? For example, what if a sequence of Shape contains Rectangle and Circle instances, and we just want to select all of the Rectangle instances?  Well, let’s say we had this sequence of Shape: 1: var shapes = new List<Shape> 2: { 3: new Rectangle { Width = 3, Height = 5 }, 4: new Rectangle { Width = 10, Height = 13 }, 5: new Circle { Radius = 10 }, 6: new Square { Side = 13 }, 7: // ... 8: }; Well, we could get the rectangles using Select(), like: 1: var onlyRectangles = shapes.Where(s => s is Rectangle).ToList(); But fortunately, an easier way has already been written for us in the form of the OfType<T>() extension method: 1: // returns only a sequence of the shapes that are Rectangles 2: var onlyRectangles = shapes.OfType<Rectangle>().ToList(); Now we have a sequence of only the Rectangles in the original sequence, we can also use this to chain other queries that depend on Rectangles, such as: 1: // select only Rectangles, then filter to only those more than 2: // 5 units wide... 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); The OfType<Rectangle>() will filter the sequence to only the items that are of type Rectangle (or a subclass of it), and that results in an IEnumerable<Rectangle>, we can then apply the other LINQ extension methods to query that list further. Just as Cast<TResult>() is an extension method on IEnumerable (and not IEnumerable<T>), the same is true for OfType<T>().  This means that you can use OfType<TResult>() on object-based collections as well. For example, given an ArrayList containing Shapes, as below: 1: // object-based collections are a sequence of object 2: var shapes = new ArrayList 3: { 4: new Rectangle { Width = 3, Height = 5 }, 5: new Rectangle { Width = 10, Height = 13 }, 6: new Circle { Radius = 10 }, 7: new Square { Side = 13 }, 8: // ... 9: }; We can use OfType<Rectangle> to filter the sequence to only Rectangle items (and subclasses), and then chain other LINQ expressions, since we will then be of type IEnumerable<Rectangle>: 1: // OfType() converts the sequence of object to a new sequence 2: // containing only Rectangle or sub-types of Rectangle. 3: var onlyBigRectangles = shapes.OfType<Rectangle>() 4: .Where(r => r.Width > 5) 5: .ToList(); Summary So now we’ve seen two different ways to get a sequence of a superclass or interface down to a more specific sequence of a subclass or implementation.  The Cast<TResult>() method casts every item in the source sequence to type TResult, and the OfType<TResult>() method selects only those items in the source sequence that are of type TResult. You can use these to downcast sequences, or adapt older types and sequences that only implement IEnumerable (such as DataTable, ArrayList, etc.). Technorati Tags: C#,CSharp,.NET,LINQ,Little Wonders,TypeOf,Cast,IEnumerable<T>

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• C#/.NET Little Wonders: The Nullable static class

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

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• Timeout Considerations for Solicit Response

  - by Michael Stephenson

  Background One of the clients I work with had been experiencing some issues for a while surrounding web service timeouts.  It's been a little challenging to work through the problems due to limitations in the diagnostic information available from one of the applications, but I learned some interesting things while troubleshooting the problem which don't seem to have been discussed much in the community so I thought I'd share my findings. In the scenario we have BizTalk trying to make calls to a .net web service which was exposed as a WSE 2 endpoint.  In the process BizTalk will try to make a large number of concurrent web service calls to the application, and the backend application has more than enough infrastructure and capability to handle the load. We have configured the <ConnectionManagement> section of the BizTalk configuration file to support up to 100 concurrent connections from each of our 2 BizTalk send servers to the web servers of the application. The problem we were facing was that the BizTalk side was reporting a significant number of timeouts when calling the web service.   One of the biggest issues was the challenge of being able to correlate a message from BizTalk to the IIS log in the .net application and the custom logs in the application especially when there was a fairly large number of servers hosting the web services.  However the key moment came when we were able to identify a specific call which had taken 40 seconds to execute on the server (yes a long time I know but that's a different story!).  Anyway we were able to identify that this had timed out on the BizTalk side.  Based on the normal 2 minute timeout we knew something unexpected was going on. From here I decided to do some experimentation and I wanted to start outside of BizTalk because my hunch was this was not a BizTalk behaviour but something which was being highlighted by BizTalk because of our large load.     Server-side - Sample Web Service To begin with I created a sample web service.  Nothing special just a vanilla asmx web service hosted in IIS6 on Windows 2003 Standard Edition.  The web service is just a hello world style web service as shown in the below picture.  The only key feature is that the server side web method has a 30 second sleep in it and will trace out some information before and after the thread is set to sleep.      In the configuration for this web service there again is nothing special it's pretty much the most plain simple web service you could build. Client-Side To begin looking at what was happening with our example I created a number of different ways to consume the web service. SoapHttpClientProtocol Example I created a small application which would use a normal proxy generated to call the web service.  It would iterate around a loop and make calls using the begin/end methods so I can do this asynchronously.  I would do a loop of 20 calls with the ConnectionManager configuration section supporting only 5 concurrent connections to the server.     <connectionManagement> <remove address="*"/> <add address = "*" maxconnection = "12" /> <add address = "http://<ServerName>" maxconnection = "5" />                         </connectionManagement> </system.net>     The below picture shows an example of the service calling code, key points are: I have configured the timeout of 40 seconds for the proxy I am using the asynchronous methods on the proxy to call the web service         The Test I would run the client and execute 21 calls to the web service.   The Results  Below is the client side trace showing what's happening on the client. In the below diagram is the web service side trace showing what's happening on the server Some observations on the results are: All of the calls were successful from the clients perspective You could see the next call starting on the server as soon as the previous one had completed Calls took significantly longer than 40 seconds from the start of our call to the return. In fact call 20 took 2 minutes and 30 seconds from the perspective of my code to execute even though I had set the timeout to 40 seconds     WSE 2 Sample In the second example I used the exact same code to call the web service again with a single exception that I modified the web service proxy to derive from WebServiceClient protocol which is part of WSE 2 (using SP3).  The below picture shows the basic code and the key points are: I have configured the timeout of 40 seconds for the proxy I am using the asynchronous methods on the proxy to call the web service        The Test This test would execute 21 calls from the client to the web service.   The Results  The below trace is from the client side: The below trace is from the server side:   Some observations on the trace results for this scenario are: With call 4 if you look at the server side trace it did not start executing on the server for a number of seconds after the other 4 initial calls which were accepted by the server. I re-ran the test and this happened a couple of times and not on most others so at this point I'm just putting this down to something unexpected happening on the development machine and we will leave this observation out of scope of this article. You can see that the client side trace statement executed almost immediately in all cases All calls after the initial few calls would timeout On the client side the calls that did timeout; timed out in a longer duration than the 40 seconds we set as the timeout You can see that as calls were completing on the server the next calls were starting to come through The calls that timed out on the client did actually connect to the server and their server side execution completed successfully     Elaboration on the findings Based on the above observations I have drawn the below sequence diagram to illustrate conceptually what is happening.  Everything except the final web service object is on the client side of the call. In the diagram below I've put two notes on the Web Service Proxy to show the two different places where the different base classes seem to start their timeout counters. From the earlier samples we can work out that the timeout counter for the WSE web service proxy starts before the one for the SoapHttpClientProtocol proxy and the WSE one includes the time to get a connection from the pool; whereas the Soap proxy timeout just covers the method execution. One interesting observation is if we rerun the above sample and increase the number of calls from 21 to 100,000 then for the WSE sample we will see a similar pattern where everything after the first few calls will timeout on the client as soon as it makes a connection to the server whereas the soap proxy will happily plug away and process all of the calls without a single timeout. I have actually set the sample running overnight and this did happen. At this point you are probably thinking the same thoughts I was at the time about the differences in behaviour and which is right and why are they different? I'm not sure there is a definitive answer to this in the documentation, or at least not that I could find! I think you just have to consider that they are different and they could have different effects depending on your messaging solution. In lots of situations this is just not an issue as your concurrent requests doesn't get to the situation where you end up throttling the web service calls on the client side, however this is definitely more common with an integration broker such as BizTalk where you often have high throughput requirements.  Some of the considerations you should make Based on this behaviour you should be aware of the following: In a .net application if you are making lots of concurrent web service calls from an application in an asynchronous manner your user may thing they are experiencing poor performance but you think your web service is working well. The problem could be that the client will have a default of 2 connections to remote servers so you should bear this in mind When you are developing a BizTalk solution or a .net solution with the WSE 2 stack you may experience timeouts under load and throttling the number of connections using the max connections element in the configuration file will not help you For an application using WSE2 or SoapHttpClientProtocol an expired timeout will not throw an error until after a connection to the server has been made so you should consider this in your transaction and durability patterns     Our Work Around In the short term for our specific scenario we know that we can handle this by just increasing our timeout value.  There is only a specific small window when we get lots of concurrent traffic that causes this scenario so we should be able to increase the timeout to take into consideration the additional client side wait, and on the odd occasion where we do get a timeout the BizTalk send port retry will handle this. What was causing our original problem was that for that short window we were getting a lot of retries which significantly increased the load on our send servers and highlighted the issue.  Longer Term Solution As a longer term solution this really gives us more ammunition to argue a migration to WCF. The application we are calling has some factors which limit the protocols we can use but with WCF we would have more control on the various timeout options because in WCF you can configure specific parts of the timeout. Summary I've had this blog post on my to do list for ages but hopefully it will be useful to some people to just understand this behaviour and to possibly help you with some performance issues you may have. I do not believe there is too much in the way of documentation particularly around WSE2 and ASMX in this area so again another bit of ammunition for migrating to WCF. I'll try to do a follow up post with the sample for WCF to show how this changes things.

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• Adopting Technologies for the Sake of Technologies

  - by shiju

  Unlike other engineering industries, the software engineering industry is really lacking maturity. The lack of maturity can see in different aspects of entire software development life cycle. I think other engineering industries are well organised and structured with common, proven engineering practices. The software engineering industry is greatly a diverse industry with different operating systems, and variety of development platforms, programming languages, frameworks and tools. Now these days, people are going behind the hypes and intellectual thoughts without understanding their core business problems and adopting technologies and practices for the sake of technologies and practices and simply becoming a “poster child” of technologies and practices. Understanding the core business problem and providing best, solid solution with a platform neutral approach, will give you more business values and ROI, instead of blindly adopting technologies and tailor-made your applications for the sake of technologies and practices. People have been simply migrating their solutions in favour of new technologies and different versions of frameworks without any business need. The “Pepsi Challenge” in the Software Development  Pepsi Challenge marketing campaign of the 1980s was a popular and very interesting marketing promotion in which people taste one cup of Pepsi and another cup with Coca Cola. In the taste test, more than 50% of people were preferred Pepsi  over Coca Cola. The success story behind the Pepsi was more sweetness contains in the Pepsi cola. They have simply added more sugar and more people preferred more sweet flavour. You can’t simply identify the better one after sipping one cup of cola based on the sweetness which contains. These things have been happening in the software industry for choosing development frameworks and technologies. People have been simply choosing frameworks based on the initial sugary feeling without understanding its core strengths and weakness. The sugary framework might be more harmful when you develop real-world systems. There is not any silver bullet for solving all kind of problems and frameworks and tools do have strengths and weakness. So it would be better to understand their strength and weakness. And please keep in mind that you have to develop real apps to understand the real capabilities and weakness of a framework. Evaluating a technology based on few blog posts will harm your projects and these bloggers might be lacking real-world experience with the framework. The Problem with Align a Development Practice with Tools Recently I have observed a discussion in a group where one guy asked suggestions for practicing Continuous Delivery (CD) as part of the agile based application engineering. Then the discussion quickly went to using and choosing a Continuous Integration (CI) tool and different people suggested different Continuous Integration (CI) tools for simply practicing Continuous Delivery. If you have worked with core agile engineering practices, you could clearly know that the real essence of agile is neither choosing a tool nor choosing a process. By simply choosing CI tool from a particular vendor will not ensure that you are delivering an evolving software based on customer feedback. You have to understand the real essence of a engineering practice and choose a right tool for practicing it instead of simply focus on a particular tool for a practicing an development practice. If you want to adopt a practice, you need a solid understanding on it with its real essence where tools are just helping us for better automation. Adopting New Technologies for the Sake of Technologies The another problem is that developers have been a tendency to adopt new technologies and simply migrating their existing apps to new technologies. It is okay if your existing system is having problem  with a technology stack or or maintainability challenge with existing solution, and moving to new technology for solving the current problems. We have been adopting new technologies for solving new challenges like solving the scalability challenges when the application or user bases is growing unpredictably. Please keep in mind that all new technologies will become old after working with it for few years. The below Facebook status update of Janakiraman, expresses the attitude of a typical customer. For an example, Node.js is becoming a hottest buzzword in the software industry and many developers are trying to adopt Node.js for their apps. The important thing is that Node.js is a minimalist framework that does some great things for some problems, but it’s not a silver bullet. I have been also working with Node.js which is good for some problems, but really bad for choosing it for all kind of problems. By adopting new technologies for new projects is good if we could get real business values from it because newer framework would solve some existing well known problems and provide better solutions where it can incorporate good solutions for the latest challenges . But adopting a new technology for the sake of new technology is really bad idea. Another example is JavaScript is getting lot of attention so that lot of developers are developing heavy JavaScript centric web apps. First, they will adopt a client-side JavaScript MV* framework from AngularJS, Ember, Backbone etc, and develop a Single Page App(SPA) where they are repeating the mistakes we did in the past with server-side. The mistakes we did in the server-side is transforming to client-side. The problem is that people are just adopting new technologies, but not improving their solutions. I predict that many Single Page App will suck in the future. We need a hybrid approach where we should be able to leverage both server-side and client-side for developing next-generation web apps. The another problem is that if you like a particular framework, use it for all kind of apps. In the past, I know some Silverlight passionate guys were tried to use that framework for all kind of apps including larger line of business apps. And these days developers are migrating their existing Silverlight apps in favour of HTML5 buzzword. So the real question is, what is the business values we are getting from these apps when we are developing it for the sake of a particular technology instead of business need. The another problem is that our solutions consultants are trying to provide unnecessary solutions for the sake of a particular technology or for a hype. For an example, Big Data solutions are great for solving the problem of three Vs : volume, velocity and variety. But trying to put this for every application will make problems. Let’s say, there is a small web site running with limited budget and saying that we need a recommendation engine for the web site with a Hadoop based solution with a 16 node cluster, would be really horrible. If we really need a Hadoop based solution, got for it, but trying to put this for all application would be a big disaster. It would be great if could understand the core business problems first, and later choose a right framework for providing solutions for the actual business problem, instead of trying to provide so many solutions. The Problem with Tied Up to a Platform Vendor Some organizations and teams are tied up with a particular platform vendor where they don’t want to use any product other than their preferred or existing platform vendor. They will accept any product provided by the vendor regardless of its capability. This will lets you some benefits regards with integration and collaboration of different products provided by the same vendor, but it will loose your opportunity to provide better solution for your business problems. For a real world sample scenario, lot of companies have been using SAP for their ERP solutions. When they are thinking about mobility or thinking about developing hybrid mobile apps, they can easily find out a framework from SAP. SAP provides a framework for HTML 5 based UI development named SAPUI5. If you are simply adopting that framework only based for the preference of existing platform vendor, you might be loose different opportunities for providing better solution. Initially you might enjoy the sugary feeling provided by the platform vendor, but you have to think about developing apps which should be capable for solving future challenges. I am not saying that any framework is not good and I believe that all frameworks are good over another one for solving at least one problem. My point is that we should not tied up with any specific platform vendor unless your organization is having resource availability problems. Being Polyglot for Providing Right Solutions The modern software engineering industry is greatly diverse with different tools and platforms. Lot of open source frameworks and new programming languages have been releasing to the developer community, where choosing the right platform without any biased opinion, is really a difficult task. But it would really great if we could develop an attitude with platform neutral mindset and being a polyglot developer for providing better solutions based on the actual business problems. IMHO, we should learn a new programming language and a new framework every year. This will improve the quality of our developer capabilities and also improve the quality of our primary programming language skills. Being polyglot for individual developers and organizational teams will give you greater opportunity to your developer experience and also for your applications. Organizations can analyse their business problem without tied with any technology and later they can provide solutions by choosing different platform and tools. Summary    In this blog post, what I was trying to say that we should not tied up or biased with any development platform, technology, vendor or programming language and we should not adopt technologies and practices for the sake of technologies. If we are adopting a technology or a practice for the sake of it, we are simply becoming a “poster child” of the technology and practice. We should not become a poster child of other people’s intellectual thoughts and theories, instead of it we should become solutions developers and solutions consultants where we should be able to provide better solutions for the business problems. Being a polyglot developer is a good idea for improving your developer skills which lets you provide better solutions for the business problems. The most important thing is that we should become platform neutral developers where our passion should be for providing brilliant solutions. It would be great if we could provide minimalist, pragmatic business solutions. You can follow me on Twitter @shijucv

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• Developing a SQL Server Function in a Test-Harness.

  - by Phil Factor

  /* Many times, it is a lot quicker to take some pain up-front and make a proper development/test harness for a routine (function or procedure) rather than think ‘I’m feeling lucky today!’. Then, you keep code and harness together from then on. Every time you run the build script, it runs the test harness too.  The advantage is that, if the test harness persists, then it is much less likely that someone, probably ‘you-in-the-future’  unintentionally breaks the code. If you store the actual code for the procedure as well as the test harness, then it is likely that any bugs in functionality will break the build rather than to introduce subtle bugs later on that could even slip through testing and get into production.   This is just an example of what I mean.   Imagine we had a database that was storing addresses with embedded UK postcodes. We really wouldn’t want that. Instead, we might want the postcode in one column and the address in another. In effect, we’d want to extract the entire postcode string and place it in another column. This might be part of a table refactoring or int could easily be part of a process of importing addresses from another system. We could easily decide to do this with a function that takes in a table as its parameter, and produces a table as its output. This is all very well, but we’d need to work on it, and test it when you make an alteration. By its very nature, a routine like this either works very well or horribly, but there is every chance that you might introduce subtle errors by fidding with it, and if young Thomas, the rather cocky developer who has just joined touches it, it is bound to break.     right, we drop the function we’re developing and re-create it. This is so we avoid the problem of having to change CREATE to ALTER when working on it. */ IF EXISTS(SELECT * FROM sys.objects WHERE name LIKE ‘ExtractPostcode’                                      and schema_name(schema_ID)=‘Dbo’)     DROP FUNCTION dbo.ExtractPostcode GO   /* we drop the user-defined table type and recreate it */ IF EXISTS(SELECT * FROM sys.types WHERE name LIKE ‘AddressesWithPostCodes’                                    and schema_name(schema_ID)=‘Dbo’)   DROP TYPE dbo.AddressesWithPostCodes GO /* we drop the user defined table type and recreate it */ IF EXISTS(SELECT * FROM sys.types WHERE name LIKE ‘OutputFormat’                                    and schema_name(schema_ID)=‘Dbo’)   DROP TYPE dbo.OutputFormat GO   /* and now create the table type that we can use to pass the addresses to the function */ CREATE TYPE AddressesWithPostCodes AS TABLE ( AddressWithPostcode_ID INT IDENTITY PRIMARY KEY, –because they work better that way! Address_ID INT NOT NULL, –the address we are fixing TheAddress VARCHAR(100) NOT NULL –The actual address ) GO CREATE TYPE OutputFormat AS TABLE (   Address_ID INT PRIMARY KEY, –the address we are fixing   TheAddress VARCHAR(1000) NULL, –The actual address   ThePostCode VARCHAR(105) NOT NULL – The Postcode )   GO CREATE FUNCTION ExtractPostcode(@AddressesWithPostCodes AddressesWithPostCodes READONLY)  /** summary:   > This Table-valued function takes a table type as a parameter, containing a table of addresses along with their integer IDs. Each address has an embedded postcode somewhere in it but not consistently in a particular place. The routine takes out the postcode and puts it in its own column, passing back a table where theinteger key is accompanied by the address without the (first) postcode and the postcode. If no postcode, then the address is returned unchanged and the postcode will be a blank string Author: Phil Factor Revision: 1.3 date: 20 May 2014 example:      – code: returns:   > Table of  Address_ID, TheAddress and ThePostCode. **/     RETURNS @FixedAddresses TABLE   (   Address_ID INT, –the address we are fixing   TheAddress VARCHAR(1000) NULL, –The actual address   ThePostCode VARCHAR(105) NOT NULL – The Postcode   ) AS – body of the function BEGIN DECLARE @BlankRange VARCHAR(10) SELECT  @BlankRange = CHAR(0)+‘- ‘+CHAR(160) INSERT INTO @FixedAddresses(Address_ID, TheAddress, ThePostCode) SELECT Address_ID,          CASE WHEN start>0 THEN REPLACE(STUFF([Theaddress],start,matchlength,”),‘  ‘,‘ ‘)             ELSE TheAddress END            AS TheAddress,        CASE WHEN Start>0 THEN SUBSTRING([Theaddress],start,matchlength-1) ELSE ” END AS ThePostCode FROM (–we have a derived table with the results we need for the chopping SELECT MAX(PATINDEX([matched],‘ ‘+[Theaddress] collate SQL_Latin1_General_CP850_Bin)) AS start,         MAX( CASE WHEN PATINDEX([matched],‘ ‘+[Theaddress] collate SQL_Latin1_General_CP850_Bin)>0 THEN TheLength ELSE 0 END) AS matchlength,        MAX(TheAddress) AS TheAddress,        Address_ID FROM (SELECT –first the match, then the length. There are three possible valid matches         ‘%['+@BlankRange+'][A-Z][0-9] [0-9][A-Z][A-Z]%’, 7 –seven character postcode       UNION ALL SELECT ‘%['+@BlankRange+'][A-Z][A-Z0-9][A-Z0-9] [0-9][A-Z][A-Z]%’, 8       UNION ALL SELECT ‘%['+@BlankRange+'][A-Z][A-Z][A-Z0-9][A-Z0-9] [0-9][A-Z][A-Z]%’, 9)      AS f(Matched,TheLength) CROSS JOIN  @AddressesWithPostCodes GROUP BY [address_ID] ) WORK; RETURN END GO ——————————-end of the function————————   IF NOT EXISTS (SELECT * FROM sys.objects WHERE name LIKE ‘ExtractPostcode’)   BEGIN   RAISERROR (‘There was an error creating the function.’,16,1)   RETURN   END   /* now the job is only half done because we need to make sure that it works. So we now load our sample data, making sure that for each Sample, we have what we actually think the output should be. */ DECLARE @InputTable AddressesWithPostCodes INSERT INTO  @InputTable(Address_ID,TheAddress) VALUES(1,’14 Mason mews, Awkward Hill, Bibury, Cirencester, GL7 5NH’), (2,’5 Binney St      Abbey Ward    Buckinghamshire      HP11 2AX UK’), (3,‘BH6 3BE 8 Moor street, East Southbourne and Tuckton W     Bournemouth UK’), (4,’505 Exeter Rd,   DN36 5RP Hawerby cum BeesbyLincolnshire UK’), (5,”), (6,’9472 Lind St,    Desborough    Northamptonshire NN14 2GH  NN14 3GH UK’), (7,’7457 Cowl St, #70      Bargate Ward  Southampton   SO14 3TY UK’), (8,”’The Pippins”, 20 Gloucester Pl, Chirton Ward,   Tyne & Wear   NE29 7AD UK’), (9,’929 Augustine lane,    Staple Hill Ward     South Gloucestershire      BS16 4LL UK’), (10,’45 Bradfield road, Parwich   Derbyshire    DE6 1QN UK’), (11,’63A Northampton St,   Wilmington    Kent   DA2 7PP UK’), (12,’5 Hygeia avenue,      Loundsley Green WardDerbyshire    S40 4LY UK’), (13,’2150 Morley St,Dee Ward      Dumfries and Galloway      DG8 7DE UK’), (14,’24 Bolton St,   Broxburn, Uphall and Winchburg    West Lothian  EH52 5TL UK’), (15,’4 Forrest St,   Weston-Super-Mare    North Somerset       BS23 3HG UK’), (16,’89 Noon St,     Carbrooke     Norfolk       IP25 6JQ UK’), (17,’99 Guthrie St,  New Milton    Hampshire     BH25 5DF UK’), (18,’7 Richmond St,  Parkham       Devon  EX39 5DJ UK’), (19,’9165 laburnum St,     Darnall Ward  Yorkshire, South     S4 7WN UK’)   Declare @OutputTable  OutputFormat  –the table of what we think the correct results should be Declare @IncorrectRows OutputFormat –done for error reporting   –here is the table of what we think the output should be, along with a few edge cases. INSERT INTO  @OutputTable(Address_ID,TheAddress, ThePostcode)     VALUES         (1, ’14 Mason mews, Awkward Hill, Bibury, Cirencester, ‘,‘GL7 5NH’),         (2, ’5 Binney St   Abbey Ward    Buckinghamshire      UK’,‘HP11 2AX’),         (3, ’8 Moor street, East Southbourne and Tuckton W    Bournemouth UK’,‘BH6 3BE’),         (4, ’505 Exeter Rd,Hawerby cum Beesby   Lincolnshire UK’,‘DN36 5RP’),         (5, ”,”),         (6, ’9472 Lind St,Desborough    Northamptonshire NN14 3GH UK’,‘NN14 2GH’),         (7, ’7457 Cowl St, #70    Bargate Ward  Southampton   UK’,‘SO14 3TY’),         (8, ”’The Pippins”, 20 Gloucester Pl, Chirton Ward,Tyne & Wear   UK’,‘NE29 7AD’),         (9, ’929 Augustine lane,  Staple Hill Ward     South Gloucestershire      UK’,‘BS16 4LL’),         (10, ’45 Bradfield road, ParwichDerbyshire    UK’,‘DE6 1QN’),         (11, ’63A Northampton St,Wilmington    Kent   UK’,‘DA2 7PP’),         (12, ’5 Hygeia avenue,    Loundsley Green WardDerbyshire    UK’,‘S40 4LY’),         (13, ’2150 Morley St,     Dee Ward      Dumfries and Galloway      UK’,‘DG8 7DE’),         (14, ’24 Bolton St,Broxburn, Uphall and Winchburg    West Lothian  UK’,‘EH52 5TL’),         (15, ’4 Forrest St,Weston-Super-Mare    North Somerset       UK’,‘BS23 3HG’),         (16, ’89 Noon St,  Carbrooke     Norfolk       UK’,‘IP25 6JQ’),         (17, ’99 Guthrie St,      New Milton    Hampshire     UK’,‘BH25 5DF’),         (18, ’7 Richmond St,      Parkham       Devon  UK’,‘EX39 5DJ’),         (19, ’9165 laburnum St,   Darnall Ward  Yorkshire, South     UK’,‘S4 7WN’)       insert into @IncorrectRows(Address_ID,TheAddress, ThePostcode)        SELECT Address_ID,TheAddress,ThePostCode FROM dbo.ExtractPostcode(@InputTable)       EXCEPT     SELECT Address_ID,TheAddress,ThePostCode FROM @outputTable; If @@RowCount>0        Begin        PRINT ‘The following rows gave ‘;     SELECT Address_ID,TheAddress,ThePostCode FROM @IncorrectRows        RAISERROR (‘These rows gave unexpected results.’,16,1);     end   /* For tear-down, we drop the user defined table type */ IF EXISTS(SELECT * FROM sys.types WHERE name LIKE ‘OutputFormat’                                    and schema_name(schema_ID)=‘Dbo’)   DROP TYPE dbo.OutputFormat GO /* once this is working, the development work turns from a chore into a delight and one ends up hitting execute so much more often to catch mistakes as soon as possible. It also prevents a wildly-broken routine getting into a build! */

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• C#/.NET Little Wonders: Skip() and Take()

  - by James Michael Hare

  Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. I’ve covered many valuable methods from System.Linq class library before, so you already know it’s packed with extension-method goodness.  Today I’d like to cover two small families I’ve neglected to mention before: Skip() and Take().  While these methods seem so simple, they are an easy way to create sub-sequences for IEnumerable<T>, much the way GetRange() creates sub-lists for List<T>. Skip() and SkipWhile() The Skip() family of methods is used to ignore items in a sequence until either a certain number are passed, or until a certain condition becomes false.  This makes the methods great for starting a sequence at a point possibly other than the first item of the original sequence.   The Skip() family of methods contains the following methods (shown below in extension method syntax): Skip(int count) Ignores the specified number of items and returns a sequence starting at the item after the last skipped item (if any).  SkipWhile(Func<T, bool> predicate) Ignores items as long as the predicate returns true and returns a sequence starting with the first item to invalidate the predicate (if any).  SkipWhile(Func<T, int, bool> predicate) Same as above, but passes not only the item itself to the predicate, but also the index of the item.  For example: 1: var list = new[] { 3.14, 2.72, 42.0, 9.9, 13.0, 101.0 }; 2:  3: // sequence contains { 2.72, 42.0, 9.9, 13.0, 101.0 } 4: var afterSecond = list.Skip(1); 5: Console.WriteLine(string.Join(", ", afterSecond)); 6:  7: // sequence contains { 42.0, 9.9, 13.0, 101.0 } 8: var afterFirstDoubleDigit = list.SkipWhile(v => v < 10.0); 9: Console.WriteLine(string.Join(", ", afterFirstDoubleDigit)); Note that the SkipWhile() stops skipping at the first item that returns false and returns from there to the rest of the sequence, even if further items in that sequence also would satisfy the predicate (otherwise, you’d probably be using Where() instead, of course). If you do use the form of SkipWhile() which also passes an index into the predicate, then you should keep in mind that this is the index of the item in the sequence you are calling SkipWhile() from, not the index in the original collection.  That is, consider the following: 1: var list = new[] { 1.0, 1.1, 1.2, 2.2, 2.3, 2.4 }; 2:  3: // Get all items < 10, then 4: var whatAmI = list 5: .Skip(2) 6: .SkipWhile((i, x) => i > x); For this example the result above is 2.4, and not 1.2, 2.2, 2.3, 2.4 as some might expect.  The key is knowing what the index is that’s passed to the predicate in SkipWhile().  In the code above, because Skip(2) skips 1.0 and 1.1, the sequence passed to SkipWhile() begins at 1.2 and thus it considers the “index” of 1.2 to be 0 and not 2.  This same logic applies when using any of the extension methods that have an overload that allows you to pass an index into the delegate, such as SkipWhile(), TakeWhile(), Select(), Where(), etc.  It should also be noted, that it’s fine to Skip() more items than exist in the sequence (an empty sequence is the result), or even to Skip(0) which results in the full sequence.  So why would it ever be useful to return Skip(0) deliberately?  One reason might be to return a List<T> as an immutable sequence.  Consider this class: 1: public class MyClass 2: { 3: private List<int> _myList = new List<int>(); 4:  5: // works on surface, but one can cast back to List<int> and mutate the original... 6: public IEnumerable<int> OneWay 7: { 8: get { return _myList; } 9: } 10:  11: // works, but still has Add() etc which throw at runtime if accidentally called 12: public ReadOnlyCollection<int> AnotherWay 13: { 14: get { return new ReadOnlyCollection<int>(_myList); } 15: } 16:  17: // immutable, can't be cast back to List<int>, doesn't have methods that throw at runtime 18: public IEnumerable<int> YetAnotherWay 19: { 20: get { return _myList.Skip(0); } 21: } 22: } This code snippet shows three (among many) ways to return an internal sequence in varying levels of immutability.  Obviously if you just try to return as IEnumerable<T> without doing anything more, there’s always the danger the caller could cast back to List<T> and mutate your internal structure.  You could also return a ReadOnlyCollection<T>, but this still has the mutating methods, they just throw at runtime when called instead of giving compiler errors.  Finally, you can return the internal list as a sequence using Skip(0) which skips no items and just runs an iterator through the list.  The result is an iterator, which cannot be cast back to List<T>.  Of course, there’s many ways to do this (including just cloning the list, etc.) but the point is it illustrates a potential use of using an explicit Skip(0). Take() and TakeWhile() The Take() and TakeWhile() methods can be though of as somewhat of the inverse of Skip() and SkipWhile().  That is, while Skip() ignores the first X items and returns the rest, Take() returns a sequence of the first X items and ignores the rest.  Since they are somewhat of an inverse of each other, it makes sense that their calling signatures are identical (beyond the method name obviously): Take(int count) Returns a sequence containing up to the specified number of items. Anything after the count is ignored. TakeWhile(Func<T, bool> predicate) Returns a sequence containing items as long as the predicate returns true.  Anything from the point the predicate returns false and beyond is ignored. TakeWhile(Func<T, int, bool> predicate) Same as above, but passes not only the item itself to the predicate, but also the index of the item. So, for example, we could do the following: 1: var list = new[] { 1.0, 1.1, 1.2, 2.2, 2.3, 2.4 }; 2:  3: // sequence contains 1.0 and 1.1 4: var firstTwo = list.Take(2); 5:  6: // sequence contains 1.0, 1.1, 1.2 7: var underTwo = list.TakeWhile(i => i < 2.0); The same considerations for SkipWhile() with index apply to TakeWhile() with index, of course.  Using Skip() and Take() for sub-sequences A few weeks back, I talked about The List<T> Range Methods and showed how they could be used to get a sub-list of a List<T>.  This works well if you’re dealing with List<T>, or don’t mind converting to List<T>.  But if you have a simple IEnumerable<T> sequence and want to get a sub-sequence, you can also use Skip() and Take() to much the same effect: 1: var list = new List<double> { 1.0, 1.1, 1.2, 2.2, 2.3, 2.4 }; 2:  3: // results in List<T> containing { 1.2, 2.2, 2.3 } 4: var subList = list.GetRange(2, 3); 5:  6: // results in sequence containing { 1.2, 2.2, 2.3 } 7: var subSequence = list.Skip(2).Take(3); I say “much the same effect” because there are some differences.  First of all GetRange() will throw if the starting index or the count are greater than the number of items in the list, but Skip() and Take() do not.  Also GetRange() is a method off of List<T>, thus it can use direct indexing to get to the items much more efficiently, whereas Skip() and Take() operate on sequences and may actually have to walk through the items they skip to create the resulting sequence.  So each has their pros and cons.  My general rule of thumb is if I’m already working with a List<T> I’ll use GetRange(), but for any plain IEnumerable<T> sequence I’ll tend to prefer Skip() and Take() instead. Summary The Skip() and Take() families of LINQ extension methods are handy for producing sub-sequences from any IEnumerable<T> sequence.  Skip() will ignore the specified number of items and return the rest of the sequence, whereas Take() will return the specified number of items and ignore the rest of the sequence.  Similarly, the SkipWhile() and TakeWhile() methods can be used to skip or take items, respectively, until a given predicate returns false.    Technorati Tags: C#, CSharp, .NET, LINQ, IEnumerable<T>, Skip, Take, SkipWhile, TakeWhile

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• Story of success: MySQL Enterprise Backup (MEB) was successfully integrated with IBM Tivoli Storage Manager (TSM) via System Backup to Tape (SBT) interface.

  - by user13334359

  Since version 3.6 MEB supports backups to tape through the SBT interface.The officially supported tool for such backups to tape is Oracle Secure Backup (OSB).But there are a lot of other Storage Managers. MEB allows to use them through the SBT interface. Since version 3.7 it also has option --sbt-environment which allows to pass environment variables, not needed by OSB, to third-party managers. At the same time MEB can not guarantee it would work with all of them.This month we were contacted by a customer who wanted to use IBM Tivoli Storage Manager (TSM) with MEB. We could only say them same thing I wrote in previous paragraph: this solution is supposed to work, but you have to be pioneers of this technology. And they agreed. They agreed to be the pioneers and so the story begins.MEB requires following options to be specified by those who want to connect it to SBT interface:--sbt-database-name: a name which should be handed over to SBT interface. This can be any name. Default, MySQL, works for most cases, so user is not required to specify this option.--sbt-lib-path: path to SBT library. For TSM this library comes with "Data Protection for Oracle", which, in its turn, interfaces with Oracle Recovery Manager (RMAN), which uses SBT interface. So you need to install it even if you don't use Oracle.--sbt-environment: environment for third-party manager. This option is not needed when you use OSB, but almost always necessary for third-party SBT managers. TSM requires variable TDPO_OPTFILE to be set and point to the TSM configuration file.--backup-image=sbt:: path to the image. Prefix "sbt:" indicates that image should be sent through SBT interfaceSo full command in our case would look like: ./mysqlbackup --port=3307 --protocol=tcp --user=backup_user --password=foobar \ --backup-image=sbt:my-first-backup --sbt-lib-path=/usr/lib/libobk.so \ --sbt-environment="TDPO_OPTFILE=/path/to/my/tdpo.opt" --backup-dir=/path/to/my/dir backup-to-imageAnd this command results in the following output log: MySQL Enterprise Backup version 3.7.1 [2012/02/16] Copyright (c) 2003, 2012, Oracle and/or its affiliates. All Rights Reserved. INFO: Starting with following command line ...  ./mysqlbackup --port=3307 --protocol=tcp --user=backup_user         --password=foobar --backup-image=sbt:my-first-backup         --sbt-lib-path=/usr/lib/libobk.so         --sbt-environment="TDPO_OPTFILE=/path/to/my/tdpo.opt"         --backup-dir=/path/to/my/dir backup-to-image sbt-environment: 'TDPO_OPTFILE=/path/to/my/tdpo.opt' INFO: Got some server configuration information from running server. IMPORTANT: Please check that mysqlbackup run completes successfully.             At the end of a successful 'backup-to-image' run mysqlbackup             prints "mysqlbackup completed OK!". --------------------------------------------------------------------                        Server Repository Options: --------------------------------------------------------------------   datadir                          =  /path/to/data   innodb_data_home_dir             =  /path/to/data   innodb_data_file_path            =  ibdata1:2048M;ibdata2:2048M;ibdata3:64M:autoextend:max:2048M   innodb_log_group_home_dir        =  /path/to/data   innodb_log_files_in_group        =  2   innodb_log_file_size             =  268435456 --------------------------------------------------------------------                        Backup Config Options: --------------------------------------------------------------------   datadir                          =  /path/to/my/dir/datadir   innodb_data_home_dir             =  /path/to/my/dir/datadir   innodb_data_file_path            =  ibdata1:2048M;ibdata2:2048M;ibdata3:64M:autoextend:max:2048M   innodb_log_group_home_dir        =  /path/to/my/dir/datadir   innodb_log_files_in_group        =  2   innodb_log_file_size             =  268435456 Backup Image Path= sbt:my-first-backup mysqlbackup: INFO: Unique generated backup id for this is 13297406400663200 120220 08:54:00 mysqlbackup: INFO: meb_sbt_session_open: MMS is 'Data Protection for Oracle: version 5.5.1.0' 120220 08:54:00 mysqlbackup: INFO: meb_sbt_session_open: MMS version '5.5.1.0' mysqlbackup: INFO: Uses posix_fadvise() for performance optimization. mysqlbackup: INFO: System tablespace file format is Antelope. mysqlbackup: INFO: Found checkpoint at lsn 31668381. mysqlbackup: INFO: Starting log scan from lsn 31668224. 120220  8:54:00 mysqlbackup: INFO: Copying log... 120220  8:54:00 mysqlbackup: INFO: Log copied, lsn 31668381.           We wait 1 second before starting copying the data files... 120220  8:54:01 mysqlbackup: INFO: Copying /path/to/ibdata/ibdata1 (Antelope file format). mysqlbackup: Progress in MB: 200 400 600 800 1000 1200 1400 1600 1800 2000 120220  8:55:30 mysqlbackup: INFO: Copying /path/to/ibdata/ibdata2 (Antelope file format). mysqlbackup: Progress in MB: 200 400 600 800 1000 1200 1400 1600 1800 2000 120220  8:57:18 mysqlbackup: INFO: Copying /path/to/ibdata/ibdata3 (Antelope file format). mysqlbackup: INFO: Preparing to lock tables: Connected to mysqld server. 120220 08:57:22 mysqlbackup: INFO: Starting to lock all the tables.... 120220 08:57:22 mysqlbackup: INFO: All tables are locked and flushed to disk mysqlbackup: INFO: Opening backup source directory '/path/to/data/' 120220 08:57:22 mysqlbackup: INFO: Starting to backup all files in subdirectories of '/path/to/data/' mysqlbackup: INFO: Backing up the database directory 'mysql' mysqlbackup: INFO: Backing up the database directory 'test' mysqlbackup: INFO: Copying innodb data and logs during final stage ... mysqlbackup: INFO: A copied database page was modified at 31668381.           (This is the highest lsn found on page)           Scanned log up to lsn 31670396.           Was able to parse the log up to lsn 31670396.           Maximum page number for a log record 328 120220 08:57:23 mysqlbackup: INFO: All tables unlocked mysqlbackup: INFO: All MySQL tables were locked for 0.000 seconds 120220 08:59:01 mysqlbackup: INFO: meb_sbt_backup_close: blocks: 4162  size: 1048576  bytes: 4363985063 120220  8:59:01 mysqlbackup: INFO: Full backup completed! mysqlbackup: INFO: MySQL binlog position: filename bin_mysql.001453, position 2105 mysqlbackup: WARNING: backup-image already closed mysqlbackup: INFO: Backup image created successfully.:            Image Path: 'sbt:my-first-backup' -------------------------------------------------------------    Parameters Summary -------------------------------------------------------------    Start LSN                  : 31668224    End LSN                    : 31670396 ------------------------------------------------------------- mysqlbackup completed OK!Backup successfully completed.To restore it you should use same commands like you do for any other MEB image, but need to provide sbt* options as well: $./mysqlbackup --backup-image=sbt:my-first-backup --sbt-lib-path=/usr/lib/libobk.so \ --sbt-environment="TDPO_OPTFILE=/path/to/my/tdpo.opt" --backup-dir=/path/to/my/dir image-to-backup-dirThen apply log as usual: $./mysqlbackup --backup-dir=/path/to/my/dir apply-logThen stop mysqld and finally copy-back: $./mysqlbackup --defaults-file=path/to/my.cnf --backup-dir=/path/to/my/dir copy-back  Disclaimer. This is only story of one success which can be useful for someone else. MEB is not regularly tested and not guaranteed to work with IBM TSM or any other third-party storage manager.

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• C#/.NET Little Wonders: Constraining Generics with Where Clause

  - by James Michael Hare

  Back when I was primarily a C++ developer, I loved C++ templates.  The power of writing very reusable generic classes brought the art of programming to a brand new level.  Unfortunately, when .NET 1.0 came about, they didn’t have a template equivalent.  With .NET 2.0 however, we finally got generics, which once again let us spread our wings and program more generically in the world of .NET However, C# generics behave in some ways very differently from their C++ template cousins.  There is a handy clause, however, that helps you navigate these waters to make your generics more powerful. The Problem – C# Assumes Lowest Common Denominator In C++, you can create a template and do nearly anything syntactically possible on the template parameter, and C++ will not check if the method/fields/operations invoked are valid until you declare a realization of the type.  Let me illustrate with a C++ example: 1: // compiles fine, C++ makes no assumptions as to T 2: template <typename T> 3: class ReverseComparer 4: { 5: public: 6: int Compare(const T& lhs, const T& rhs) 7: { 8: return rhs.CompareTo(lhs); 9: } 10: }; Notice that we are invoking a method CompareTo() off of template type T.  Because we don’t know at this point what type T is, C++ makes no assumptions and there are no errors. C++ tends to take the path of not checking the template type usage until the method is actually invoked with a specific type, which differs from the behavior of C#: 1: // this will NOT compile! C# assumes lowest common denominator. 2: public class ReverseComparer<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } So why does C# give us a compiler error even when we don’t yet know what type T is?  This is because C# took a different path in how they made generics.  Unless you specify otherwise, for the purposes of the code inside the generic method, T is basically treated like an object (notice I didn’t say T is an object). That means that any operations, fields, methods, properties, etc that you attempt to use of type T must be available at the lowest common denominator type: object.  Now, while object has the broadest applicability, it also has the fewest specific.  So how do we allow our generic type placeholder to do things more than just what object can do? Solution: Constraint the Type With Where Clause So how do we get around this in C#?  The answer is to constrain the generic type placeholder with the where clause.  Basically, the where clause allows you to specify additional constraints on what the actual type used to fill the generic type placeholder must support. You might think that narrowing the scope of a generic means a weaker generic.  In reality, though it limits the number of types that can be used with the generic, it also gives the generic more power to deal with those types.  In effect these constraints says that if the type meets the given constraint, you can perform the activities that pertain to that constraint with the generic placeholders. Constraining Generic Type to Interface or Superclass One of the handiest where clause constraints is the ability to specify the type generic type must implement a certain interface or be inherited from a certain base class. For example, you can’t call CompareTo() in our first C# generic without constraints, but if we constrain T to IComparable<T>, we can: 1: public class ReverseComparer<T> 2: where T : IComparable<T> 3: { 4: public int Compare(T lhs, T rhs) 5: { 6: return lhs.CompareTo(rhs); 7: } 8: } Now that we’ve constrained T to an implementation of IComparable<T>, this means that our variables of generic type T may now call any members specified in IComparable<T> as well.  This means that the call to CompareTo() is now legal. If you constrain your type, also, you will get compiler warnings if you attempt to use a type that doesn’t meet the constraint.  This is much better than the syntax error you would get within C++ template code itself when you used a type not supported by a C++ template. Constraining Generic Type to Only Reference Types Sometimes, you want to assign an instance of a generic type to null, but you can’t do this without constraints, because you have no guarantee that the type used to realize the generic is not a value type, where null is meaningless. Well, we can fix this by specifying the class constraint in the where clause.  By declaring that a generic type must be a class, we are saying that it is a reference type, and this allows us to assign null to instances of that type: 1: public static class ObjectExtensions 2: { 3: public static TOut Maybe<TIn, TOut>(this TIn value, Func<TIn, TOut> accessor) 4: where TOut : class 5: where TIn : class 6: { 7: return (value != null) ? accessor(value) : null; 8: } 9: } In the example above, we want to be able to access a property off of a reference, and if that reference is null, pass the null on down the line.  To do this, both the input type and the output type must be reference types (yes, nullable value types could also be considered applicable at a logical level, but there’s not a direct constraint for those). Constraining Generic Type to only Value Types Similarly to constraining a generic type to be a reference type, you can also constrain a generic type to be a value type.  To do this you use the struct constraint which specifies that the generic type must be a value type (primitive, struct, enum, etc). Consider the following method, that will convert anything that is IConvertible (int, double, string, etc) to the value type you specify, or null if the instance is null. 1: public static T? ConvertToNullable<T>(IConvertible value) 2: where T : struct 3: { 4: T? result = null; 5:  6: if (value != null) 7: { 8: result = (T)Convert.ChangeType(value, typeof(T)); 9: } 10:  11: return result; 12: } Because T was constrained to be a value type, we can use T? (System.Nullable<T>) where we could not do this if T was a reference type. Constraining Generic Type to Require Default Constructor You can also constrain a type to require existence of a default constructor.  Because by default C# doesn’t know what constructors a generic type placeholder does or does not have available, it can’t typically allow you to call one.  That said, if you give it the new() constraint, it will mean that the type used to realize the generic type must have a default (no argument) constructor. Let’s assume you have a generic adapter class that, given some mappings, will adapt an item from type TFrom to type TTo.  Because it must create a new instance of type TTo in the process, we need to specify that TTo has a default constructor: 1: // Given a set of Action<TFrom,TTo> mappings will map TFrom to TTo 2: public class Adapter<TFrom, TTo> : IEnumerable<Action<TFrom, TTo>> 3: where TTo : class, new() 4: { 5: // The list of translations from TFrom to TTo 6: public List<Action<TFrom, TTo>> Translations { get; private set; } 7:  8: // Construct with empty translation and reverse translation sets. 9: public Adapter() 10: { 11: // did this instead of auto-properties to allow simple use of initializers 12: Translations = new List<Action<TFrom, TTo>>(); 13: } 14:  15: // Add a translator to the collection, useful for initializer list 16: public void Add(Action<TFrom, TTo> translation) 17: { 18: Translations.Add(translation); 19: } 20:  21: // Add a translator that first checks a predicate to determine if the translation 22: // should be performed, then translates if the predicate returns true 23: public void Add(Predicate<TFrom> conditional, Action<TFrom, TTo> translation) 24: { 25: Translations.Add((from, to) => 26: { 27: if (conditional(from)) 28: { 29: translation(from, to); 30: } 31: }); 32: } 33:  34: // Translates an object forward from TFrom object to TTo object. 35: public TTo Adapt(TFrom sourceObject) 36: { 37: var resultObject = new TTo(); 38:  39: // Process each translation 40: Translations.ForEach(t => t(sourceObject, resultObject)); 41:  42: return resultObject; 43: } 44:  45: // Returns an enumerator that iterates through the collection. 46: public IEnumerator<Action<TFrom, TTo>> GetEnumerator() 47: { 48: return Translations.GetEnumerator(); 49: } 50:  51: // Returns an enumerator that iterates through a collection. 52: IEnumerator IEnumerable.GetEnumerator() 53: { 54: return GetEnumerator(); 55: } 56: } Notice, however, you can’t specify any other constructor, you can only specify that the type has a default (no argument) constructor. Summary The where clause is an excellent tool that gives your .NET generics even more power to perform tasks higher than just the base "object level" behavior.  There are a few things you cannot specify with constraints (currently) though: Cannot specify the generic type must be an enum. Cannot specify the generic type must have a certain property or method without specifying a base class or interface – that is, you can’t say that the generic must have a Start() method. Cannot specify that the generic type allows arithmetic operations. Cannot specify that the generic type requires a specific non-default constructor. In addition, you cannot overload a template definition with different, opposing constraints.  For example you can’t define a Adapter<T> where T : struct and Adapter<T> where T : class.  Hopefully, in the future we will get some of these things to make the where clause even more useful, but until then what we have is extremely valuable in making our generics more user friendly and more powerful!   Technorati Tags: C#,.NET,Little Wonders,BlackRabbitCoder,where,generics

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• Make Your Menu Item Highlighted

  - by Shaun

  When I was working on the TalentOn project (Promotion in MSDN Chinese) I was asked to implement a functionality that makes the top menu items highlighted when the currently viewing page was in that section. This might be a common scenario in the web application development I think.   Simple Example When thinking about the solution of the highlighted menu items the biggest problem would be how to define the sections (menu item) and the pages it belongs to rather than making the menu highlighted. With the ASP.NET MVC framework we can use the controller – action infrastructure for us to achieve it. Each controllers would have a related menu item on the master page normally. The menu item would be highlighted if any of the views under this controller are being shown. Some specific menu items would be highlighted of that action was invoked, for example the home page, the about page, etc. The check rule can be specified on-demand. For example I can define the action LogOn and Register of Account controller should make the Account menu item highlighted while the ChangePassword should make the Profile menu item highlighted. I’m going to use the HtmlHelper to render the highlight-able menu item. The key point is that I need to pass the predication to check whether the current view belongs to this menu item which means this menu item should be highlighted or not. Hence I need a delegate as its parameter. The simplest code would be like this. 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Web; 5: using System.Web.Mvc; 6: using System.Web.Mvc.Html; 7:  8: namespace ShaunXu.Blogs.HighlighMenuItem 9: { 10: public static class HighlightMenuItemHelper 11: { 12: public static MvcHtmlString HighlightMenuItem(this HtmlHelper helper, 13: string text, string controllerName, string actionName, object routeData, object htmlAttributes, 14: string highlightText, object highlightHtmlAttributes, 15: Func<HtmlHelper, bool> highlightPredicate) 16: { 17: var shouldHighlight = highlightPredicate.Invoke(helper); 18: if (shouldHighlight) 19: { 20: return helper.ActionLink(string.IsNullOrWhiteSpace(highlightText) ? text : highlightText, 21: actionName, controllerName, routeData, highlightHtmlAttributes == null ? htmlAttributes : highlightHtmlAttributes); 22: } 23: else 24: { 25: return helper.ActionLink(text, actionName, controllerName, routeData, htmlAttributes); 26: } 27: } 28: } 29: } There are 3 groups of the parameters: the first group would be the same as the in-build ActionLink method parameters. It has the link text, controller name and action name, etc passed in so that I can render a valid linkage for the menu item. The second group would be more focus on the highlight link text and Html attributes. I will use them to render the highlight menu item. The third group, which contains one parameter, would be a predicate that tells me whether this menu item should be highlighted or not based on the user’s definition. And then I changed my master page of the sample MVC application. I let the Home and About menu highlighted only when the Index and About action are invoked. And I added a new menu named Account which should be highlighted for all actions/views under its Account controller. So my master would be like this. 1: <div id="menucontainer"> 2:  3: <ul id="menu"> 4: <li><% 1: : Html.HighlightMenuItem( 2: "Home", "Home", "Index", null, null, 3: "[Home]", null, 4: helper => helper.ViewContext.RouteData.Values["controller"].ToString() == "Home" 5: && helper.ViewContext.RouteData.Values["action"].ToString() == "Index")%></li> 5:  6: <li><% 1: : Html.HighlightMenuItem( 2: "About", "Home", "About", null, null, 3: "[About]", null, 4: helper => helper.ViewContext.RouteData.Values["controller"].ToString() == "Home" 5: && helper.ViewContext.RouteData.Values["action"].ToString() == "About")%></li> 7:  8: <li><% 1: : Html.HighlightMenuItem( 2: "Account", "Account", "LogOn", null, null, 3: "[Account]", null, 4: helper => helper.ViewContext.RouteData.Values["controller"].ToString() == "Account")%></li> 9: 10: </ul> 11:  12: </div> Note: You need to add the import section for the namespace “ShaunXu.Blogs.HighlighMenuItem” to make the extension method I created below available. So let’s see the result. When the home page was shown the Home menu was highlighted since at this moment it was controller = Home and action = Index. And if I clicked the About menu you can see it turned highlighted as now the action was About. And if I navigated to the register page the Account menu was highlighted since it should be like that when any actions under the Account controller was invoked.   Fluently Language Till now it’s a fully example for the highlight menu item but not perfect yet. Since the most common scenario would be: highlighted when the action invoked, or highlighted when any action was invoked under this controller, we can created 2 shortcut method so for them so that normally the developer will be no need to specify the delegation. Another place we can improve would be, to make the method more user-friendly, or I should say developer-friendly. As you can see when we want to add a highlight menu item we need to specify 8 parameters and we need to remember what they mean. In fact we can make the method more “fluently” so that the developer can have the hints when using it by the Visual Studio IntelliSense. Below is the full code for it. 1: using System; 2: using System.Collections.Generic; 3: using System.Linq; 4: using System.Web; 5: using System.Web.Mvc; 6: using System.Web.Mvc.Html; 7:  8: namespace Ethos.Xrm.HR 9: { 10: #region Helper 11:  12: public static class HighlightActionMenuHelper 13: { 14: public static IHighlightActionMenuProviderAfterCreated HighlightActionMenu(this HtmlHelper helper) 15: { 16: return new HighlightActionMenuProvider(helper); 17: } 18: } 19:  20: #endregion 21:  22: #region Interfaces 23:  24: public interface IHighlightActionMenuProviderAfterCreated 25: { 26: IHighlightActionMenuProviderAfterOn On(string actionName, string controllerName); 27: } 28:  29: public interface IHighlightActionMenuProviderAfterOn 30: { 31: IHighlightActionMenuProviderAfterWith With(string text, object routeData, object htmlAttributes); 32: } 33:  34: public interface IHighlightActionMenuProviderAfterWith 35: { 36: IHighlightActionMenuProviderAfterHighlightWhen HighlightWhen(Func<HtmlHelper, bool> predicate); 37: IHighlightActionMenuProviderAfterHighlightWhen HighlightWhenControllerMatch(); 38: IHighlightActionMenuProviderAfterHighlightWhen HighlightWhenControllerAndActionMatch(); 39: } 40:  41: public interface IHighlightActionMenuProviderAfterHighlightWhen 42: { 43: IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(object highlightHtmlAttributes, string highlightText); 44: IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(object highlightHtmlAttributes); 45: IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(string cssClass, string highlightText); 46: IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(string cssClass); 47: } 48:  49: public interface IHighlightActionMenuProviderAfterApplyHighlightStyle 50: { 51: MvcHtmlString ToActionLink(); 52: } 53:  54: #endregion 55:  56: public class HighlightActionMenuProvider : 57: IHighlightActionMenuProviderAfterCreated, 58: IHighlightActionMenuProviderAfterOn, IHighlightActionMenuProviderAfterWith, 59: IHighlightActionMenuProviderAfterHighlightWhen, IHighlightActionMenuProviderAfterApplyHighlightStyle 60: { 61: private HtmlHelper _helper; 62:  63: private string _controllerName; 64: private string _actionName; 65: private string _text; 66: private object _routeData; 67: private object _htmlAttributes; 68:  69: private Func<HtmlHelper, bool> _highlightPredicate; 70:  71: private string _highlightText; 72: private object _highlightHtmlAttributes; 73:  74: public HighlightActionMenuProvider(HtmlHelper helper) 75: { 76: _helper = helper; 77: } 78:  79: public IHighlightActionMenuProviderAfterOn On(string actionName, string controllerName) 80: { 81: _actionName = actionName; 82: _controllerName = controllerName; 83: return this; 84: } 85:  86: public IHighlightActionMenuProviderAfterWith With(string text, object routeData, object htmlAttributes) 87: { 88: _text = text; 89: _routeData = routeData; 90: _htmlAttributes = htmlAttributes; 91: return this; 92: } 93:  94: public IHighlightActionMenuProviderAfterHighlightWhen HighlightWhen(Func<HtmlHelper, bool> predicate) 95: { 96: _highlightPredicate = predicate; 97: return this; 98: } 99:  100: public IHighlightActionMenuProviderAfterHighlightWhen HighlightWhenControllerMatch() 101: { 102: return HighlightWhen((helper) => 103: { 104: return helper.ViewContext.RouteData.Values["controller"].ToString().ToLower() == _controllerName.ToLower(); 105: }); 106: } 107:  108: public IHighlightActionMenuProviderAfterHighlightWhen HighlightWhenControllerAndActionMatch() 109: { 110: return HighlightWhen((helper) => 111: { 112: return helper.ViewContext.RouteData.Values["controller"].ToString().ToLower() == _controllerName.ToLower() && 113: helper.ViewContext.RouteData.Values["action"].ToString().ToLower() == _actionName.ToLower(); 114: }); 115: } 116:  117: public IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(object highlightHtmlAttributes, string highlightText) 118: { 119: _highlightText = highlightText; 120: _highlightHtmlAttributes = highlightHtmlAttributes; 121: return this; 122: } 123:  124: public IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(object highlightHtmlAttributes) 125: { 126: return ApplyHighlighStyle(highlightHtmlAttributes, _text); 127: } 128:  129: public IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(string cssClass, string highlightText) 130: { 131: return ApplyHighlighStyle(new { @class = cssClass }, highlightText); 132: } 133:  134: public IHighlightActionMenuProviderAfterApplyHighlightStyle ApplyHighlighStyle(string cssClass) 135: { 136: return ApplyHighlighStyle(new { @class = cssClass }, _text); 137: } 138:  139: public MvcHtmlString ToActionLink() 140: { 141: if (_highlightPredicate.Invoke(_helper)) 142: { 143: // should be highlight 144: return _helper.ActionLink(_highlightText, _actionName, _controllerName, _routeData, _highlightHtmlAttributes); 145: } 146: else 147: { 148: // should not be highlight 149: return _helper.ActionLink(_text, _actionName, _controllerName, _routeData, _htmlAttributes); 150: } 151: } 152: } 153: } So in the master page when I need the highlight menu item I can “tell” the helper how it should be, just like this. 1: <li> 2: <% 1: : Html.HighlightActionMenu() 2: .On("Index", "Home") 3: .With(SiteMasterStrings.Home, null, null) 4: .HighlightWhenControllerMatch() 5: .ApplyHighlighStyle(new { style = "background:url(../../Content/Images/topmenu_bg.gif) repeat-x;text-decoration:none;color:#feffff;" }) 6: .ToActionLink() %> 3: </li> While I’m typing the code the IntelliSense will advise me that I need a highlight action menu, on the Index action of the Home controller, with the “Home” as its link text and no need the additional route data and Html attributes, and it should be highlighted when the controller was “Home”, and if it’s highlighted the style should be like this and finally render it to me. This is something we call “Fluently Language”. If you had been using Moq you will see that’s very development-friendly, document-ly and easy to read.   Summary In this post I demonstrated how to implement a highlight menu item in ASP.NET MVC by using its controller – action infrastructure. We can see the ASP.NET MVC helps us to organize our web application better. And then I also told a little bit more on the “Fluently Language” and showed how it will make our code better and easy to be used.   Hope this helps, Shaun   All documents and related graphics, codes are provided "AS IS" without warranty of any kind. Copyright © Shaun Ziyan Xu. This work is licensed under the Creative Commons License.

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• Filtering List Data with a jQuery-searchFilter Plugin

  - by Rick Strahl

  When dealing with list based data on HTML forms, filtering that data down based on a search text expression is an extremely useful feature. We’re used to search boxes on just about anything these days and HTML forms should be no different. In this post I’ll describe how you can easily filter a list down to just the elements that match text typed into a search box. It’s a pretty simple task and it’s super easy to do, but I get a surprising number of comments from developers I work with who are surprised how easy it is to hook up this sort of behavior, that I thought it’s worth a blog post. But Angular does that out of the Box, right? These days it seems everybody is raving about Angular and the rich SPA features it provides. One of the cool features of Angular is the ability to do drop dead simple filters where you can specify a filter expression as part of a looping construct and automatically have that filter applied so that only items that match the filter show. I think Angular has single handedly elevated search filters to first rate, front-row status because it’s so easy. I love using Angular myself, but Angular is not a generic solution to problems like this. For one thing, using Angular requires you to render the list data with Angular – if you have data that is server rendered or static, then Angular doesn’t work. Not all applications are client side rendered SPAs – not by a long shot, and nor do all applications need to become SPAs. Long story short, it’s pretty easy to achieve text filtering effects using jQuery (or plain JavaScript for that matter) with just a little bit of work. Let’s take a look at an example. Why Filter? Client side filtering is a very useful tool that can make it drastically easier to sift through data displayed in client side lists. In my applications I like to display scrollable lists that contain a reasonably large amount of data, rather than the classic paging style displays which tend to be painful to use. So I often display 50 or so items per ‘page’ and it’s extremely useful to be able to filter this list down. Here’s an example in my Time Trakker application where I can quickly glance at various common views of my time entries. I can see Recent Entries, Unbilled Entries, Open Entries etc and filter those down by individual customers and so forth. Each of these lists results tends to be a few pages worth of scrollable content. The following screen shot shows a filtered view of Recent Entries that match the search keyword of CellPage: As you can see in this animated GIF, the filter is applied as you type, displaying only entries that match the text anywhere inside of the text of each of the list items. This is an immediately useful feature for just about any list display and adds significant value. A few lines of jQuery The good news is that this is trivially simple using jQuery. To get an idea what this looks like, here’s the relevant page layout showing only the search box and the list layout:<div id="divItemWrapper"> <div class="time-entry"> <div class="time-entry-right"> May 11, 2014 - 7:20pm<br /> <span style='color:steelblue'>0h:40min</span><br /> <a id="btnDeleteButton" href="#" class="hoverbutton" data-id="16825"> <img src="images/remove.gif" /> </a> </div> <div class="punchedoutimg"></div> <b><a href='/TimeTrakkerWeb/punchout/16825'>Project Housekeeping</a></b><br /> <small><i>Sawgrass</i></small> </div> ... more items here </div> So we have a searchbox txtSearchPage and a bunch of DIV elements with a .time-entry CSS class attached that makes up the list of items displayed. To hook up the search filter with jQuery is merely a matter of a few lines of jQuery code hooked to the .keyup() event handler: <script type="text/javascript"> $("#txtSearchPage").keyup(function() { var search = $(this).val(); $(".time-entry").show(); if (search) $(".time-entry").not(":contains(" + search + ")").hide(); }); </script> The idea here is pretty simple: You capture the keystroke in the search box and capture the search text. Using that search text you first make all items visible and then hide all the items that don’t match. Since DOM changes are applied after a method finishes execution in JavaScript, the show and hide operations are effectively batched up and so the view changes only to the final list rather than flashing the whole list and then removing items on a slow machine. You get the desired effect of the list showing the items in question. Case Insensitive Filtering But there is one problem with the solution above: The jQuery :contains filter is case sensitive, so your search text has to match expressions explicitly which is a bit cumbersome when typing. In the screen capture above I actually cheated – I used a custom filter that provides case insensitive contains behavior. jQuery makes it really easy to create custom query filters, and so I created one called containsNoCase. Here’s the implementation of this custom filter:$.expr[":"].containsNoCase = function(el, i, m) { var search = m[3]; if (!search) return false; return new RegExp(search, "i").test($(el).text()); }; This filter can be added anywhere where page level JavaScript runs – in page script or a seperately loaded .js file.  The filter basically extends jQuery with a : expression. Filters get passed a tokenized array that contains the expression. In this case the m[3] contains the search text from inside of the brackets. A filter basically looks at the active element that is passed in and then can return true or false to determine whether the item should be matched. Here I check a regular expression that looks for the search text in the element’s text. So the code for the filter now changes to:$(".time-entry").not(":containsNoCase(" + search + ")").hide(); And voila – you now have a case insensitive search.You can play around with another simpler example using this Plunkr:http://plnkr.co/edit/hDprZ3IlC6uzwFJtgHJh?p=preview Wrapping it up in a jQuery Plug-in To make this even easier to use and so that you can more easily remember how to use this search type filter, we can wrap this logic into a small jQuery plug-in:(function($, undefined) { $.expr[":"].containsNoCase = function(el, i, m) { var search = m[3]; if (!search) return false; return new RegExp(search, "i").test($(el).text()); }; $.fn.searchFilter = function(options) { var opt = $.extend({ // target selector targetSelector: "", // number of characters before search is applied charCount: 1 }, options); return this.each(function() { var $el = $(this); $el.keyup(function() { var search = $(this).val(); var $target = $(opt.targetSelector); $target.show(); if (search && search.length >= opt.charCount) $target.not(":containsNoCase(" + search + ")").hide(); }); }); }; })(jQuery); To use this plug-in now becomes a one liner:$("#txtSearchPagePlugin").searchFilter({ targetSelector: ".time-entry", charCount: 2}) You attach the .searchFilter() plug-in to the text box you are searching and specify a targetSelector that is to be filtered. Optionally you can specify a character count at which the filter kicks in since it’s kind of useless to filter at a single character typically. Summary This is s a very easy solution to a cool user interface feature your users will thank you for. Search filtering is a simple but highly effective user interface feature, and as you’ve seen in this post it’s very simple to create this behavior with just a few lines of jQuery code. While all the cool kids are doing Angular these days, jQuery is still useful in many applications that don’t embrace the ‘everything generated in JavaScript’ paradigm. I hope this jQuery plug-in or just the raw jQuery will be useful to some of you… Resources Example on Plunker© Rick Strahl, West Wind Technologies, 2005-2014Posted in jQuery  HTML5  JavaScript   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• Why Are Minimized Programs Often Slow to Open Again?

  - by Jason Fitzpatrick

  It seems particularly counterintuitive: you minimize an application because you plan on returning to it later and wish to skip shutting the application down and restarting it later, but sometimes maximizing it takes even longer than launching it fresh. What gives? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader Bart wants to know why he’s not saving any time with application minimization: I’m working in Photoshop CS6 and multiple browsers a lot. I’m not using them all at once, so sometimes some applications are minimized to taskbar for hours or days. The problem is, when I try to maximize them from the taskbar – it sometimes takes longer than starting them! Especially Photoshop feels really weird for many seconds after finally showing up, it’s slow, unresponsive and even sometimes totally freezes for minute or two. It’s not a hardware problem as it’s been like that since always on all on my PCs. Would I also notice it after upgrading my HDD to SDD and adding RAM (my main PC holds 4 GB currently)? Could guys with powerful pcs / macs tell me – does it also happen to you? I guess OSes somehow “focus” on active software and move all the resources away from the ones that run, but are not used. Is it possible to somehow set RAM / CPU / HDD priorities or something, for let’s say, Photoshop, so it won’t slow down after long period of inactivity? So what is the deal? Why does he find himself waiting to maximize a minimized app? The Answer SuperUser contributor Allquixotic explains why: Summary The immediate problem is that the programs that you have minimized are being paged out to the “page file” on your hard disk. This symptom can be improved by installing a Solid State Disk (SSD), adding more RAM to your system, reducing the number of programs you have open, or upgrading to a newer system architecture (for instance, Ivy Bridge or Haswell). Out of these options, adding more RAM is generally the most effective solution. Explanation The default behavior of Windows is to give active applications priority over inactive applications for having a spot in RAM. When there’s significant memory pressure (meaning the system doesn’t have a lot of free RAM if it were to let every program have all the RAM it wants), it starts putting minimized programs into the page file, which means it writes out their contents from RAM to disk, and then makes that area of RAM free. That free RAM helps programs you’re actively using — say, your web browser — run faster, because if they need to claim a new segment of RAM (like when you open a new tab), they can do so. This “free” RAM is also used as page cache, which means that when active programs attempt to read data on your hard disk, that data might be cached in RAM, which prevents your hard disk from being accessed to get that data. By using the majority of your RAM for page cache, and swapping out unused programs to disk, Windows is trying to improve responsiveness of the program(s) you are actively using, by making RAM available to them, and caching the files they access in RAM instead of the hard disk. The downside of this behavior is that minimized programs can take a while to have their contents copied from the page file, on disk, back into RAM. The time increases the larger the program’s footprint in memory. This is why you experience that delay when maximizing Photoshop. RAM is many times faster than a hard disk (depending on the specific hardware, it can be up to several orders of magnitude). An SSD is considerably faster than a hard disk, but it is still slower than RAM by orders of magnitude. Having your page file on an SSD will help, but it will also wear out the SSD more quickly than usual if your page file is heavily utilized due to RAM pressure. Remedies Here is an explanation of the available remedies, and their general effectiveness: Installing more RAM: This is the recommended path. If your system does not support more RAM than you already have installed, you will need to upgrade more of your system: possibly your motherboard, CPU, chassis, power supply, etc. depending on how old it is. If it’s a laptop, chances are you’ll have to buy an entire new laptop that supports more installed RAM. When you install more RAM, you reduce memory pressure, which reduces use of the page file, which is a good thing all around. You also make available more RAM for page cache, which will make all programs that access the hard disk run faster. As of Q4 2013, my personal recommendation is that you have at least 8 GB of RAM for a desktop or laptop whose purpose is anything more complex than web browsing and email. That means photo editing, video editing/viewing, playing computer games, audio editing or recording, programming / development, etc. all should have at least 8 GB of RAM, if not more. Run fewer programs at a time: This will only work if the programs you are running do not use a lot of memory on their own. Unfortunately, Adobe Creative Suite products such as Photoshop CS6 are known for using an enormous amount of memory. This also limits your multitasking ability. It’s a temporary, free remedy, but it can be an inconvenience to close down your web browser or Word every time you start Photoshop, for instance. This also wouldn’t stop Photoshop from being swapped when minimizing it, so it really isn’t a very effective solution. It only helps in some specific situations. Install an SSD: If your page file is on an SSD, the SSD’s improved speed compared to a hard disk will result in generally improved performance when the page file has to be read from or written to. Be aware that SSDs are not designed to withstand a very frequent and constant random stream of writes; they can only be written over a limited number of times before they start to break down. Heavy use of a page file is not a particularly good workload for an SSD. You should install an SSD in combination with a large amount of RAM if you want maximum performance while preserving the longevity of the SSD. Use a newer system architecture: Depending on the age of your system, you may be using an out of date system architecture. The “system architecture” is generally defined as the “generation” (think generations like children, parents, grandparents, etc.) of the motherboard and CPU. Newer generations generally support faster I/O (input/output), better memory bandwidth, lower latency, and less contention over shared resources, instead providing dedicated links between components. For example, starting with the “Nehalem” generation (around 2009), the Front-Side Bus (FSB) was eliminated, which removed a common bottleneck, because almost all system components had to share the same FSB for transmitting data. This was replaced with a “point to point” architecture, meaning that each component gets its own dedicated “lane” to the CPU, which continues to be improved every few years with new generations. You will generally see a more significant improvement in overall system performance depending on the “gap” between your computer’s architecture and the latest one available. For example, a Pentium 4 architecture from 2004 is going to see a much more significant improvement upgrading to “Haswell” (the latest as of Q4 2013) than a “Sandy Bridge” architecture from ~2010. Links Related questions: How to reduce disk thrashing (paging)? Windows Swap (Page File): Enable or Disable? Also, just in case you’re considering it, you really shouldn’t disable the page file, as this will only make matters worse; see here. And, in case you needed extra convincing to leave the Windows Page File alone, see here and here. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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• Variant Management– Which Approach fits for my Product?

  - by C. Chadwick

  Jürgen Kunz – Director Product Development – Oracle ORACLE Deutschland B.V. & Co. KG Introduction In a difficult economic environment, it is important for companies to understand the customer requirements in detail and to address them in their products. Customer specific products, however, usually cause increased costs. Variant management helps to find the best combination of standard components and custom components which balances customer’s product requirements and product costs. Depending on the type of product, different approaches to variant management will be applied. For example the automotive product “car” or electronic/high-tech products like a “computer”, with a pre-defined set of options to be combined in the individual configuration (so called “Assembled to Order” products), require a different approach to products in heavy machinery, which are (at least partially) engineered in a customer specific way (so-called “Engineered-to Order” products). This article discusses different approaches to variant management. Starting with the simple Bill of Material (BOM), this article presents three different approaches to variant management, which are provided by Agile PLM. Single level BOM and Variant BOM The single level BOM is the basic form of the BOM. The product structure is defined using assemblies and single parts. A particular product is thus represented by a fixed product structure. As soon as you have to manage product variants, the single level BOM is no longer sufficient. A variant BOM will be needed to manage product variants. The variant BOM is sometimes referred to as 150% BOM, since a variant BOM contains more parts and assemblies than actually needed to assemble the (final) product – just 150% of the parts You can evolve the variant BOM from the single level BOM by replacing single nodes with a placeholder node. The placeholder in this case represents the possible variants of a part or assembly. Product structure nodes, which are part of any product, are so-called “Must-Have” parts. “Optional” parts can be omitted in the final product. Additional attributes allow limiting the quantity of parts/assemblies which can be assigned at a certain position in the Variant BOM. Figure 1 shows the variant BOM of Agile PLM. Figure 1 Variant BOM in Agile PLM During the instantiation of the Variant BOM, the placeholders get replaced by specific variants of the parts and assemblies. The selection of the desired or appropriate variants is either done step by step by the user or by applying pre-defined configuration rules. As a result of the instantiation, an independent BOM will be created (Figure 2). Figure 2 Instantiated BOM in Agile PLM This kind of Variant BOM  can be used for „Assembled –To-Order“ type products as well as for „Engineered-to-Order“-type products. In case of “Assembled –To-Order” type products, typically the instantiation is done automatically with pre-defined configuration rules. For „Engineered- to-Order“-type products at least part of the product is selected manually to make use of customized parts/assemblies, that have been engineered according to the specific custom requirements. Template BOM The Template BOM is used for „Engineered-to-Order“-type products. It is another type of variant BOM. The engineer works in a flexible environment which allows him to build the most creative solutions. At the same time the engineer shall be guided to re-use existing solutions and it shall be assured that product variants of the same product family share the same base structure. The template BOM defines the basic structure of products belonging to the same product family. Let’s take a gearbox as an example. The customer specific configuration of the gearbox is influenced by several parameters (e.g. rpm range, transmitted torque), which are defined in the customer’s requirement document.  Figure 3 shows part of a Template BOM (yellow) and its relation to the product family hierarchy (blue).  Figure 3 Template BOM Every component of the Template BOM has links to the variants that have been engineeried so far for the component (depending on the level in the Template BOM, they are product variants, Assembly Variant or single part variants). This library of solutions, the so-called solution space, can be used by the engineers to build new product variants. In the best case, the engineer selects an existing solution variant, such as the gearbox shown in figure 3. When the existing variants do not fulfill the specific requirements, a new variant will be engineered. This new variant must be compliant with the given Template BOM. If we look at the gearbox in figure 3  it must consist of a transmission housing, a Connecting Plate, a set of Gears and a Planetary transmission – pre-assumed that all components are must have components. The new variant will enhance the solution space and is automatically available for re-use in future variants. The result of the instantiation of the Template BOM is a stand-alone BOM which represents the customer specific product variant. Modular BOM The concept of the modular BOM was invented in the automotive industry. Passenger cars are so-called „Assembled-to-Order“-products. The customer first selects the specific equipment of the car (so-called specifications) – for instance engine, audio equipment, rims, color. Based on this information the required parts will be determined and the customer specific car will be assembled. Certain combinations of specification are not available for the customer, because they are not feasible from technical perspective (e.g. a convertible with sun roof) or because the combination will not be offered for marketing reasons (e.g. steel rims with a sports line car). The modular BOM (yellow structure in figure 4) is defined in the context of a specific product family (in the sample it is product family „Speedstar“). It is the same modular BOM for the different types of cars of the product family (e.g. sedan, station wagon). The assembly or single parts of the car (blue nodes in figure 4) are assigned at the leaf level of the modular BOM. The assignment of assembly and parts to the modular BOM is enriched with a configuration rule (purple elements in figure 4). The configuration rule defines the conditions to use a specific assembly or single part. The configuration rule is valid in the context of a type of car (green elements in figure 4). Color specific parts are assigned to the color independent parts via additional configuration rules (grey elements in figure 4). The configuration rules use Boolean operators to connect the specifications. Additional consistency rules (constraints) may be used to define invalid combinations of specification (so-called exclusions). Furthermore consistency rules may be used to add specifications to the set of specifications. For instance it is important that a car with diesel engine always is build using the high capacity battery.  Figure 4 Modular BOM The calculation of the car configuration consists of several steps. First the consistency rules (constraints) are applied. Resulting from that specification might be added automatically. The second step will determine the assemblies and single parts for the complete structure of the modular BOM, by evaluating the configuration rules in the context of the current type of car. The evaluation of the rules for one component in the modular BOM might result in several rules being fulfilled. In this case the most specific rule (typically the longest rule) will win. Thanks to this approach, it is possible to add a specific variant to the modular BOM without the need to change any other configuration rules.  As a result the whole set of configuration rules is easy to maintain. Finally the color specific assemblies respective parts will be determined and the configuration is completed. Figure 5 Calculated Car Configuration The result of the car configuration is shown in figure 5. It shows the list of assemblies respective single parts (blue components in figure 5), which are required to build the customer specific car. Summary There are different approaches to variant management. Three different approaches have been presented in this article. At the end of the day, it is the type of the product which decides about the best approach.  For „Assembled to Order“-type products it is very likely that you can define the configuration rules and calculate the product variant automatically. Products of type „Engineered-to-Order“ ,however, need to be engineered. Nevertheless in the majority of cases, part of the product structure can be generated automatically in a similar way to „Assembled to Order“-tape products.  That said it is important first to analyze the product portfolio, in order to define the best approach to variant management.

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• How Mature is Your Database Change Management Process?

  - by Ben Rees

  .dbd-banner p{ font-size:0.75em; padding:0 0 10px; margin:0 } .dbd-banner p span{ color:#675C6D; } .dbd-banner p:last-child{ padding:0; } @media ALL and (max-width:640px){ .dbd-banner{ background:#f0f0f0; padding:5px; color:#333; margin-top: 5px; } } -- Database Delivery Patterns & Practices Further Reading Organization and team processes How do you get your database schema changes live, on to your production system? As your team of developers and DBAs are working on the changes to the database to support your business-critical applications, how do these updates wend their way through from dev environments, possibly to QA, hopefully through pre-production and eventually to production in a controlled, reliable and repeatable way? In this article, I describe a model we use to try and understand the different stages that customers go through as their database change management processes mature, from the very basic and manual, through to advanced continuous delivery practices. I also provide a simple chart that will help you determine “How mature is our database change management process?” This process of managing changes to the database – which all of us who have worked in application/database development have had to deal with in one form or another – is sometimes known as Database Change Management (even if we’ve never used the term ourselves). And it’s a difficult process, often painfully so. Some developers take the approach of “I’ve no idea how my changes get live – I just write the stored procedures and add columns to the tables. It’s someone else’s problem to get this stuff live. I think we’ve got a DBA somewhere who deals with it – I don’t know, I’ve never met him/her”. I know I used to work that way. I worked that way because I assumed that making the updates to production was a trivial task – how hard can it be? Pause the application for half an hour in the middle of the night, copy over the changes to the app and the database, and switch it back on again? Voila! But somehow it never seemed that easy. And it certainly was never that easy for database changes. Why? Because you can’t just overwrite the old database with the new version. Databases have a state – more specifically 4Tb of critical data built up over the last 12 years of running your business, and if your quick hotfix happened to accidentally delete that 4Tb of data, then you’re “Looking for a new role” pretty quickly after the failed release. There are a lot of other reasons why a managed database change management process is important for organisations, besides job security, not least: Frequency of releases. Many business managers are feeling the pressure to get functionality out to their users sooner, quicker and more reliably. The new book (which I highly recommend) Lean Enterprise by Jez Humble, Barry O’Reilly and Joanne Molesky provides a great discussion on how many enterprises are having to move towards a leaner, more frequent release cycle to maintain their competitive advantage. It’s no longer acceptable to release once per year, leaving your customers waiting all year for changes they desperately need (and expect) Auditing and compliance. SOX, HIPAA and other compliance frameworks have demanded that companies implement proper processes for managing changes to their databases, whether managing schema changes, making sure that the data itself is being looked after correctly or other mechanisms that provide an audit trail of changes. We’ve found, at Red Gate that we have a very wide range of customers using every possible form of database change management imaginable. Everything from “Nothing – I just fix the schema on production from my laptop when things go wrong, and write it down in my notebook” to “A full Continuous Delivery process – any change made by a dev gets checked in and recorded, fully tested (including performance tests) before a (tested) release is made available to our Release Management system, ready for live deployment!”. And everything in between of course. Because of the vast number of customers using so many different approaches we found ourselves struggling to keep on top of what everyone was doing – struggling to identify patterns in customers’ behavior. This is useful for us, because we want to try and fit the products we have to different needs – different products are relevant to different customers and we waste everyone’s time (most notably, our customers’) if we’re suggesting products that aren’t appropriate for them. If someone visited a sports store, looking to embark on a new fitness program, and the store assistant suggested the latest $10,000 multi-gym, complete with multiple weights mechanisms, dumb-bells, pull-up bars and so on, then he’s likely to lose that customer. All he needed was a pair of running shoes! To solve this issue – in an attempt to simplify how we understand our customers and our offerings – we built a model. This is a an attempt at trying to classify our customers in to some sort of model or “Customer Maturity Framework” as we rather grandly term it, which somehow simplifies our understanding of what our customers are doing. The great statistician, George Box (amongst other things, the “Box” in the Box-Jenkins time series model) gave us the famous quote: “Essentially all models are wrong, but some are useful” We’ve taken this quote to heart – we know it’s a gross over-simplification of the real world of how users work with complex legacy and new database developments. Almost nobody precisely fits in to one of our categories. But we hope it’s useful and interesting. There are actually a number of similar models that exist for more general application delivery. We’ve found these from ThoughtWorks/Forrester, from InfoQ and others, and initially we tried just taking these models and replacing the word “application” for “database”. However, we hit a problem. From talking to our customers we know that users are far less further down the road of mature database change management than they are for application development. As a simple example, no application developer, who wants to keep his/her job would develop an application for an organisation without source controlling that code. Sure, he/she might not be using an advanced Gitflow branching methodology but they’ll certainly be making sure their code gets managed in a repo somewhere with all the benefits of history, auditing and so on. But this certainly isn’t the case (yet) for the database – a very large segment of the people we speak to have no source control set up for their databases whatsoever, even at the most basic level (for example, keeping change scripts in a source control system somewhere). By the way, if this is you, Red Gate has a great whitepaper here, on the barriers people face getting a source control process implemented at their organisations. This difference in maturity is the same as you move in to areas such as continuous integration (common amongst app developers, relatively rare for database developers) and automated release management (growing amongst app developers, very rare for the database). So, when we created the model we started from scratch and biased the levels of maturity towards what we actually see amongst our customers. But, what are these stages? And what level are you? The table below describes our definitions for four levels of maturity – Baseline, Beginner, Intermediate and Advanced. As I say, this is a model – you won’t fit any of these categories perfectly, but hopefully one will ring true more than others. We’ve also created a PDF with a flow chart to help you find which of these groups most closely matches your team:  Download the Database Delivery Maturity Framework PDF here   Level D1 – Baseline Work directly on live databases Sometimes work directly in production Generate manual scripts for releases. Sometimes use a product like SQL Compare or similar to do this Any tests that we might have are run manually Level D2 – Beginner Have some ad-hoc DB version control such as manually adding upgrade scripts to a version control system Attempt is made to keep production in sync with development environments There is some documentation and planning of manual deployments Some basic automated DB testing in process Level D3 – Intermediate The database is fully version-controlled with a product like Red Gate SQL Source Control or SSDT Database environments are managed Production environment schema is reproducible from the source control system There are some automated tests Have looked at using migration scripts for difficult database refactoring cases Level D4 – Advanced Using continuous integration for database changes Build, testing and deployment of DB changes carried out through a proper database release process Fully automated tests Production system is monitored for fast feedback to developers   Does this model reflect your team at all? Where are you on this journey? We’d be very interested in knowing how you get on. We’re doing a lot of work at the moment, at Red Gate, trying to help people progress through these stages. For example, if you’re currently not source controlling your database, then this is a natural next step. If you are already source controlling your database, what about the next stage – continuous integration and automated release management? To help understand these issues, there’s a summary of the Red Gate Database Delivery learning program on our site, alongside a Patterns and Practices library here on Simple-Talk and a Training Academy section on our documentation site to help you get up and running with the tools you need to progress. All feedback is welcome and it would be great to hear where you find yourself on this journey! This article is part of our database delivery patterns & practices series on Simple Talk. Find more articles for version control, automated testing, continuous integration & deployment.

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• Key ATG architecture principles

  - by Glen Borkowski

  Overview The purpose of this article is to describe some of the important foundational concepts of ATG.  This is not intended to cover all areas of the ATG platform, just the most important subset - the ones that allow ATG to be extremely flexible, configurable, high performance, etc.  For more information on these topics, please see the online product manuals. Modules The first concept is called the 'ATG Module'.  Simply put, you can think of modules as the building blocks for ATG applications.  The ATG development team builds the out of the box product using modules (these are the 'out of the box' modules).  Then, when a customer is implementing their site, they build their own modules that sit 'on top' of the out of the box ATG modules.  Modules can be very simple - containing minimal definition, and perhaps a small amount of configuration.  Alternatively, a module can be rather complex - containing custom logic, database schema definitions, configuration, one or more web applications, etc.  Modules generally will have dependencies on other modules (the modules beneath it).  For example, the Commerce Reference Store module (CRS) requires the DCS (out of the box commerce) module. Modules have a ton of value because they provide a way to decouple a customers implementation from the out of the box ATG modules.  This allows for a much easier job when it comes time to upgrade the ATG platform.  Modules are also a very useful way to group functionality into a single package which can be leveraged across multiple ATG applications. One very important thing to understand about modules, or more accurately, ATG as a whole, is that when you start ATG, you tell it what module(s) you want to start.  One of the first things ATG does is to look through all the modules you specified, and for each one, determine a list of modules that are also required to start (based on each modules dependencies).  Once this final, ordered list is determined, ATG continues to boot up.  One of the outputs from the ordered list of modules is that each module can contain it's own classes and configuration.  During boot, the ordered list of modules drives the unified classpath and configpath.  This is what determines which classes override others, and which configuration overrides other configuration.  Think of it as a layered approach. The structure of a module is well defined.  It simply looks like a folder in a filesystem that has certain other folders and files within it.  Here is a list of items that can appear in a module: MyModule: META-INF - this is required, along with a file called MANIFEST.MF which describes certain properties of the module.  One important property is what other modules this module depends on. config - this is typically present in most modules.  It defines a tree structure (folders containing properties files, XML, etc) that maps to ATG components (these are described below). lib - this contains the classes (typically in jarred format) for any code defined in this module j2ee - this is where any web-apps would be stored. src - in case you want to include the source code for this module, it's standard practice to put it here sql - if your module requires any additions to the database schema, you should place that schema here Here's a screenshots of a module: Modules can also contain sub-modules.  A dot-notation is used when referring to these sub-modules (i.e. MyModule.Versioned, where Versioned is a sub-module of MyModule). Finally, it is important to completely understand how modules work if you are going to be able to leverage them effectively.  There are many different ways to design modules you want to create, some approaches are better than others, especially if you plan to share functionality between multiple different ATG applications. Components A component in ATG can be thought of as a single item that performs a certain set of related tasks.  An example could be a ProductViews component - used to store information about what products the current customer has viewed.  Components have properties (also called attributes).  The ProductViews component could have properties like lastProductViewed (stores the ID of the last product viewed) or productViewList (stores the ID's of products viewed in order of their being viewed).  The previous examples of component properties would typically also offer get and set methods used to retrieve and store the property values.  Components typically will also offer other types of useful methods aside from get and set.  In the ProductViewed component, we might want to offer a hasViewed method which will tell you if the customer has viewed a certain product or not. Components are organized in a tree like hierarchy called 'nucleus'.  Nucleus is used to locate and instantiate ATG Components.  So, when you create a new ATG component, it will be able to be found 'within' nucleus.  Nucleus allows ATG components to reference one another - this is how components are strung together to perform meaningful work.  It's also a mechanism to prevent redundant configuration - define it once and refer to it from everywhere. Here is a screenshot of a component in nucleus:  Components can be extremely simple (i.e. a single property with a get method), or can be rather complex offering many properties and methods.  To be an ATG component, a few things are required: a class - you can reference an existing out of the box class or you could write your own a properties file - this is used to define your component the above items must be located 'within' nucleus by placing them in the correct spot in your module's config folder Within the properties file, you will need to point to the class you want to use: $class=com.mycompany.myclass You may also want to define the scope of the class (request, session, or global): $scope=session In summary, ATG Components live in nucleus, generally have links to other components, and provide some meaningful type of work.  You can configure components as well as extend their functionality by writing code. Repositories Repositories (a.k.a. Data Anywhere Architecture) is the mechanism that ATG uses to access data primarily stored in relational databases, but also LDAP or other backend systems.  ATG applications are required to be very high performance, and data access is critical in that if not handled properly, it could create a bottleneck.  ATG's repository functionality has been around for a long time - it's proven to be extremely scalable.  Developers new to ATG need to understand how repositories work as this is a critical aspect of the ATG architecture.   Repositories essentially map relational tables to objects in ATG, as well as handle caching.  ATG defines many repositories out of the box (i.e. user profile, catalog, orders, etc), and this is comprised of both the underlying database schema along with the associated repository definition files (XML).  It is fully expected that implementations will extend / change the out of the box repository definitions, so there is a prescribed approach to doing this.  The first thing to be sure of is to encapsulate your repository definition additions / changes within your own module (as described above).  The other important best practice is to never modify the out of the box schema - in other words, don't add columns to existing ATG tables, just create your own new tables.  These will help ensure you can easily upgrade your application at a later date. xml-combination As mentioned earlier, when you start ATG, the order of the modules will determine the final configpath.  Files within this configpath are 'layered' such that modules on top can override configuration of modules below it.  This is the same concept for repository definition files.  If you want to add a few properties to the out of the box user profile, you simply need to create an XML file containing only your additions, and place it in the correct location in your module.  At boot time, your definition will be combined (hence the term xml-combination) with the lower, out of the box modules, with the result being a user profile that contains everything (out of the box, plus your additions).  Aside from just adding properties, there are also ways to remove and change properties. types of properties Aside from the normal 'database backed' properties, there are a few other interesting types: transient properties - these are properties that are in memory, but not backed by any database column.  These are useful for temporary storage. java-backed properties - by nature, these are transient, but in addition, when you access this property (by called the get method) instead of looking up a piece of data, it performs some logic and returns the results.  'Age' is a good example - if you're storing a birth date on the profile, but your business rules are defined in terms of someones age, you could create a simple java-backed property to look at the birth date and compare it to the current date, and return the persons age. derived properties - this is what allows for inheritance within the repository structure.  You could define a property at the category level, and have the product inherit it's value as well as override it.  This is useful for setting defaults, with the ability to override. caching There are a number of different caching modes which are useful at different times depending on the nature of the data being cached.  For example, the simple cache mode is useful for things like user profiles.  This is because the user profile will typically only be used on a single instance of ATG at one time.  Simple cache mode is also useful for read-only types of data such as the product catalog.  Locked cache mode is useful when you need to ensure that only one ATG instance writes to a particular item at a time - an example would be a customers order.  There are many options in terms of configuring caching which are outside the scope of this article - please refer to the product manuals for more details. Other important concepts - out of scope for this article There are a whole host of concepts that are very important pieces to the ATG platform, but are out of scope for this article.  Here's a brief description of some of them: formhandlers - these are ATG components that handle form submissions by users. pipelines - these are configurable chains of logic that are used for things like handling a request (request pipeline) or checking out an order. special kinds of repositories (versioned, files, secure, ...) - there are a couple different types of repositories that are used in various situations.  See the manuals for more information. web development - JSP/ DSP tag library - ATG provides a traditional approach to developing web applications by providing a tag library called the DSP library.  This library is used throughout your JSP pages to interact with all the ATG components. messaging - a message sub-system used as another way for components to interact. personalization - ability for business users to define a personalized user experience for customers.  See the other blog posts related to personalization.

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• Meet the New Windows Azure

  - by ScottGu

  Today we are releasing a major set of improvements to Windows Azure.  Below is a short-summary of just a few of them: New Admin Portal and Command Line Tools Today’s release comes with a new Windows Azure portal that will enable you to manage all features and services offered on Windows Azure in a seamless, integrated way.  It is very fast and fluid, supports filtering and sorting (making it much easier to use for large deployments), works on all browsers, and offers a lot of great new features – including built-in VM, Web site, Storage, and Cloud Service monitoring support. The new portal is built on top of a REST-based management API within Windows Azure – and everything you can do through the portal can also be programmed directly against this Web API. We are also today releasing command-line tools (which like the portal call the REST Management APIs) to make it even easier to script and automate your administration tasks.  We are offering both a Powershell (for Windows) and Bash (for Mac and Linux) set of tools to download.  Like our SDKs, the code for these tools is hosted on GitHub under an Apache 2 license. Virtual Machines Windows Azure now supports the ability to deploy and run durable VMs in the cloud.  You can easily create these VMs using a new Image Gallery built-into the new Windows Azure Portal, or alternatively upload and run your own custom-built VHD images. Virtual Machines are durable (meaning anything you install within them persists across reboots) and you can use any OS with them.  Our built-in image gallery includes both Windows Server images (including the new Windows Server 2012 RC) as well as Linux images (including Ubuntu, CentOS, and SUSE distributions).  Once you create a VM instance you can easily Terminal Server or SSH into it in order to configure and customize the VM however you want (and optionally capture your own image snapshot of it to use when creating new VM instances).  This provides you with the flexibility to run pretty much any workload within Windows Azure.   The new Windows Azure Portal provides a rich set of management features for Virtual Machines – including the ability to monitor and track resource utilization within them.  Our new Virtual Machine support also enables the ability to easily attach multiple data-disks to VMs (which you can then mount and format as drives).  You can optionally enable geo-replication support on these – which will cause Windows Azure to continuously replicate your storage to a secondary data-center at least 400 miles away from your primary data-center as a backup. We use the same VHD format that is supported with Windows virtualization today (and which we’ve released as an open spec), which enables you to easily migrate existing workloads you might already have virtualized into Windows Azure.  We also make it easy to download VHDs from Windows Azure, which also provides the flexibility to easily migrate cloud-based VM workloads to an on-premise environment.  All you need to do is download the VHD file and boot it up locally, no import/export steps required. Web Sites Windows Azure now supports the ability to quickly and easily deploy ASP.NET, Node.js and PHP web-sites to a highly scalable cloud environment that allows you to start small (and for free) and then scale up as your traffic grows.  You can create a new web site in Azure and have it ready to deploy to in under 10 seconds: The new Windows Azure Portal provides built-in administration support for Web sites – including the ability to monitor and track resource utilization in real-time: You can deploy to web-sites in seconds using FTP, Git, TFS and Web Deploy.  We are also releasing tooling updates today for both Visual Studio and Web Matrix that enable developers to seamlessly deploy ASP.NET applications to this new offering.  The VS and Web Matrix publishing support includes the ability to deploy SQL databases as part of web site deployment – as well as the ability to incrementally update database schema with a later deployment. You can integrate web application publishing with source control by selecting the “Set up TFS publishing” or “Set up Git publishing” links on a web-site’s dashboard: Doing do will enable integration with our new TFS online service (which enables a full TFS workflow – including elastic build and testing support), or create a Git repository that you can reference as a remote and push deployments to.  Once you push a deployment using TFS or Git, the deployments tab will keep track of the deployments you make, and enable you to select an older (or newer) deployment and quickly redeploy your site to that snapshot of the code.  This provides a very powerful DevOps workflow experience.   Windows Azure now allows you to deploy up to 10 web-sites into a free, shared/multi-tenant hosting environment (where a site you deploy will be one of multiple sites running on a shared set of server resources).  This provides an easy way to get started on projects at no cost. You can then optionally upgrade your sites to run in a “reserved mode” that isolates them so that you are the only customer within a virtual machine: And you can elastically scale the amount of resources your sites use – allowing you to increase your reserved instance capacity as your traffic scales: Windows Azure automatically handles load balancing traffic across VM instances, and you get the same, super fast, deployment options (FTP, Git, TFS and Web Deploy) regardless of how many reserved instances you use. With Windows Azure you pay for compute capacity on a per-hour basis – which allows you to scale up and down your resources to match only what you need. Cloud Services and Distributed Caching Windows Azure also supports the ability to build cloud services that support rich multi-tier architectures, automated application management, and scale to extremely large deployments.  Previously we referred to this capability as “hosted services” – with this week’s release we are now referring to this capability as “cloud services”.  We are also enabling a bunch of new features with them. Distributed Cache One of the really cool new features being enabled with cloud services is a new distributed cache capability that enables you to use and setup a low-latency, in-memory distributed cache within your applications.  This cache is isolated for use just by your applications, and does not have any throttling limits. This cache can dynamically grow and shrink elastically (without you have to redeploy your app or make code changes), and supports the full richness of the AppFabric Cache Server API (including regions, high availability, notifications, local cache and more).  In addition to supporting the AppFabric Cache Server API, it also now supports the Memcached protocol – allowing you to point code written against Memcached at it (no code changes required). The new distributed cache can be setup to run in one of two ways: 1) Using a co-located approach.  In this option you allocate a percentage of memory in your existing web and worker roles to be used by the cache, and then the cache joins the memory into one large distributed cache.  Any data put into the cache by one role instance can be accessed by other role instances in your application – regardless of whether the cached data is stored on it or another role.  The big benefit with the “co-located” option is that it is free (you don’t have to pay anything to enable it) and it allows you to use what might have been otherwise unused memory within your application VMs. 2) Alternatively, you can add “cache worker roles” to your cloud service that are used solely for caching.  These will also be joined into one large distributed cache ring that other roles within your application can access.  You can use these roles to cache 10s or 100s of GBs of data in-memory very effectively – and the cache can be elastically increased or decreased at runtime within your application: New SDKs and Tooling Support We have updated all of the Windows Azure SDKs with today’s release to include new features and capabilities.  Our SDKs are now available for multiple languages, and all of the source in them is published under an Apache 2 license and and maintained in GitHub repositories. The .NET SDK for Azure has in particular seen a bunch of great improvements with today’s release, and now includes tooling support for both VS 2010 and the VS 2012 RC. We are also now shipping Windows, Mac and Linux SDK downloads for languages that are offered on all of these systems – allowing developers to develop Windows Azure applications using any development operating system. Much, Much More The above is just a short list of some of the improvements that are shipping in either preview or final form today – there is a LOT more in today’s release.  These include new Virtual Private Networking capabilities, new Service Bus runtime and tooling support, the public preview of the new Azure Media Services, new Data Centers, significantly upgraded network and storage hardware, SQL Reporting Services, new Identity features, support within 40+ new countries and territories, and much, much more. You can learn more about Windows Azure and sign-up to try it for free at http://windowsazure.com.  You can also watch a live keynote I’m giving at 1pm June 7th (later today) where I’ll walk through all of the new features.  We will be opening up the new features I discussed above for public usage a few hours after the keynote concludes.  We are really excited to see the great applications you build with them. Hope this helps, Scott

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• Working with Timelines with LINQ to Twitter

  - by Joe Mayo

  When first working with the Twitter API, I thought that using SinceID would be an effective way to page through timelines. In practice it doesn’t work well for various reasons. To explain why, Twitter published an excellent document that is a must-read for anyone working with timelines: Twitter Documentation: Working with Timelines This post shows how to implement the recommended strategies in that document by using LINQ to Twitter. You should read the document in it’s entirety before moving on because my explanation will start at the bottom and work back up to the top in relation to the Twitter document. What follows is an explanation of SinceID, MaxID, and how they come together to help you efficiently work with Twitter timelines. The Role of SinceID Specifying SinceID says to Twitter, “Don’t return tweets earlier than this”. What you want to do is store this value after every timeline query set so that it can be reused on the next set of queries.  The next section will explain what I mean by query set, but a quick explanation is that it’s a loop that gets all new tweets. The SinceID is a backstop to avoid retrieving tweets that you already have. Here’s some initialization code that includes a variable named sinceID that will be used to populate the SinceID property in subsequent queries: // last tweet processed on previous query set ulong sinceID = 210024053698867204; ulong maxID; const int Count = 10; var statusList = new List<status>(); Here, I’ve hard-coded the sinceID variable, but this is where you would initialize sinceID from whatever storage you choose (i.e. a database). The first time you ever run this code, you won’t have a value from a previous query set. Initially setting it to 0 might sound like a good idea, but what if you’re querying a timeline with lots of tweets? Because of the number of tweets and rate limits, your query set might take a very long time to run. A caveat might be that Twitter won’t return an entire timeline back to Tweet #0, but rather only go back a certain period of time, the limits of which are documented for individual Twitter timeline API resources. So, to initialize SinceID at too low of a number can result in a lot of initial tweets, yet there is a limit to how far you can go back. What you’re trying to accomplish in your application should guide you in how to initially set SinceID. I have more to say about SinceID later in this post. The other variables initialized above include the declaration for MaxID, Count, and statusList. The statusList variable is a holder for all the timeline tweets collected during this query set. You can set Count to any value you want as the largest number of tweets to retrieve, as defined by individual Twitter timeline API resources. To effectively page results, you’ll use the maxID variable to set the MaxID property in queries, which I’ll discuss next. Initializing MaxID On your first query of a query set, MaxID will be whatever the most recent tweet is that you get back. Further, you don’t know what MaxID is until after the initial query. The technique used in this post is to do an initial query and then use the results to figure out what the next MaxID will be.  Here’s the code for the initial query: var userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.SinceID == sinceID && tweet.Count == Count select tweet) .ToList(); statusList.AddRange(userStatusResponse); // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; The query above sets both SinceID and Count properties. As explained earlier, Count is the largest number of tweets to return, but the number can be less. A couple reasons why the number of tweets that are returned could be less than Count include the fact that the user, specified by ScreenName, might not have tweeted Count times yet or might not have tweeted at least Count times within the maximum number of tweets that can be returned by the Twitter timeline API resource. Another reason could be because there aren’t Count tweets between now and the tweet ID specified by sinceID. Setting SinceID constrains the results to only those tweets that occurred after the specified Tweet ID, assigned via the sinceID variable in the query above. The statusList is an accumulator of all tweets receive during this query set. To simplify the code, I left out some logic to check whether there were no tweets returned. If  the query above doesn’t return any tweets, you’ll receive an exception when trying to perform operations on an empty list. Yeah, I cheated again. Besides querying initial tweets, what’s important about this code is the final line that sets maxID. It retrieves the lowest numbered status ID in the results. Since the lowest numbered status ID is for a tweet we already have, the code decrements the result by one to keep from asking for that tweet again. Remember, SinceID is not inclusive, but MaxID is. The maxID variable is now set to the highest possible tweet ID that can be returned in the next query. The next section explains how to use MaxID to help get the remaining tweets in the query set. Retrieving Remaining Tweets Earlier in this post, I defined a term that I called a query set. Essentially, this is a group of requests to Twitter that you perform to get all new tweets. A single query might not be enough to get all new tweets, so you’ll have to start at the top of the list that Twitter returns and keep making requests until you have all new tweets. The previous section showed the first query of the query set. The code below is a loop that completes the query set: do { // now add sinceID and maxID userStatusResponse = (from tweet in twitterCtx.Status where tweet.Type == StatusType.User && tweet.ScreenName == "JoeMayo" && tweet.Count == Count && tweet.SinceID == sinceID && tweet.MaxID == maxID select tweet) .ToList(); if (userStatusResponse.Count > 0) { // first tweet processed on current query maxID = userStatusResponse.Min( status => ulong.Parse(status.StatusID)) - 1; statusList.AddRange(userStatusResponse); } } while (userStatusResponse.Count != 0 && statusList.Count < 30); Here we have another query, but this time it includes the MaxID property. The SinceID property prevents reading tweets that we’ve already read and Count specifies the largest number of tweets to return. Earlier, I mentioned how it was important to check how many tweets were returned because failing to do so will result in an exception when subsequent code runs on an empty list. The code above protects against this problem by only working with the results if Twitter actually returns tweets. Reasons why there wouldn’t be results include: if the first query got all the new tweets there wouldn’t be more to get and there might not have been any new tweets between the SinceID and MaxID settings of the most recent query. The code for loading the returned tweets into statusList and getting the maxID are the same as previously explained. The important point here is that MaxID is being reset, not SinceID. As explained in the Twitter documentation, paging occurs from the newest tweets to oldest, so setting MaxID lets us move from the most recent tweets down to the oldest as specified by SinceID. The two loop conditions cause the loop to continue as long as tweets are being read or a max number of tweets have been read.  Logically, you want to stop reading when you’ve read all the tweets and that’s indicated by the fact that the most recent query did not return results. I put the check to stop after 30 tweets are reached to keep the demo from running too long – in the console the response scrolls past available buffer and I wanted you to be able to see the complete output. Yet, there’s another point to be made about constraining the number of items you return at one time. The Twitter API has rate limits and making too many queries per minute will result in an error from twitter that LINQ to Twitter raises as an exception. To use the API properly, you’ll have to ensure you don’t exceed this threshold. Looking at the statusList.Count as done above is rather primitive, but you can implement your own logic to properly manage your rate limit. Yeah, I cheated again. Summary Now you know how to use LINQ to Twitter to work with Twitter timelines. After reading this post, you have a better idea of the role of SinceID - the oldest tweet already received. You also know that MaxID is the largest tweet ID to retrieve in a query. Together, these settings allow you to page through results via one or more queries. You also understand what factors affect the number of tweets returned and considerations for potential error handling logic. The full example of the code for this post is included in the downloadable source code for LINQ to Twitter.   @JoeMayo

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• Using LINQ to Twitter OAuth with Windows 8

  - by Joe Mayo

  In previous posts, I explained how to use LINQ to Twitter with Windows 8, but the example was a Twitter Search, which didn’t require authentication. Much of the Twitter API requires authentication, so this post will explain how you can perform OAuth authentication with LINQ to Twitter in a Windows 8 Metro-style application. Getting Started I have earlier posts on how to create a Windows 8 app and add pages, so I’ll assume it isn’t necessary to repeat here. One difference is that I’m using Visual Studio 2012 RC and some of the terminology and/or library code might be slightly different.  Here are steps to get started: Create a new Windows metro style app, selecting the Blank App project template. Create a new Basic Page and name it OAuth.xaml.  Note: You’ll receive a prompt window for adding files and you should click Yes because those files are necessary for this demo. Add a new Basic Page named TweetPage.xaml. Open App.xaml.cs and change !rootFrame.Navigate(typeof(MainPage)) to !rootFrame.Navigate(typeof(TweetPage)). Now that the project is set up you’ll see the reason why authentication is required by setting up the TweetPage. Setting Up to Tweet a Status In this section, I’ll show you how to set up the XAML and code-behind for a tweet.  The tweet logic will check to see if the user is authenticated before performing the tweet. To tweet, I put a TextBox and Button on the XAML page. The following code omits most of the page, concentrating primarily on the elements of interest in this post: <StackPanel Grid.Row="1"> <TextBox Name="TweetTextBox" Margin="15" /> <Button Name="TweetButton" Content="Tweet" Click="TweetButton_Click" Margin="15,0" /> </StackPanel> Given the UI above, the user types the message they want to tweet, and taps Tweet. This invokes TweetButton_Click, which checks to see if the user is authenticated.  If the user is not authenticated, the app navigates to the OAuth page.  If they are authenticated, LINQ to Twitter does an UpdateStatus to post the user’s tweet.  Here’s the TweetButton_Click implementation: void TweetButton_Click(object sender, RoutedEventArgs e) { PinAuthorizer auth = null; if (SuspensionManager.SessionState.ContainsKey("Authorizer")) { auth = SuspensionManager.SessionState["Authorizer"] as PinAuthorizer; } if (auth == null || !auth.IsAuthorized) { Frame.Navigate(typeof(OAuthPage)); return; } var twitterCtx = new TwitterContext(auth); Status tweet = twitterCtx.UpdateStatus(TweetTextBox.Text); new MessageDialog(tweet.Text, "Successful Tweet").ShowAsync(); } For authentication, this app uses PinAuthorizer, one of several authorizers available in the LINQ to Twitter library. I’ll explain how PinAuthorizer works in the next section. What’s important here is that LINQ to Twitter needs an authorizer to post a Tweet. The code above checks to see if a valid authorizer is available. To do this, it uses the SuspensionManager class, which is part of the code generated earlier when creating OAuthPage.xaml. The SessionState property is a Dictionary<string, object> and I’m using the Authorizer key to store the PinAuthorizer.  If the user previously authorized during this session, the code reads the PinAuthorizer instance from SessionState and assigns it to the auth variable. If the user is authorized, auth would not be null and IsAuthorized would be true. Otherwise, the app navigates the user to OAuthPage.xaml, which I’ll discuss in more depth in the next section. When the user is authorized, the code passes the authorizer, auth, to the TwitterContext constructor. LINQ to Twitter uses the auth instance to build OAuth signatures for each interaction with Twitter.  You no longer need to write any more code to make this happen. The code above accepts the tweet just posted in the Status instance, tweet, and displays a message with the text to confirm success to the user. You can pull the PinAuthorizer instance from SessionState, instantiate your TwitterContext, and use it as you need. Just remember to make sure you have a valid authorizer, like the code above. As shown earlier, the code navigates to OAuthPage.xaml when a valid authorizer isn’t available. The next section shows how to perform the authorization upon arrival at OAuthPage.xaml. Doing the OAuth Dance This section shows how to authenticate with LINQ to Twitter’s built-in OAuth support. From the user perspective, they must be navigated to the Twitter authentication page, add credentials, be navigated to a Pin number page, and then enter that Pin in the Windows 8 application. The following XAML shows the relevant elements that the user will interact with during this process. <StackPanel Grid.Row="2"> <WebView x:Name="OAuthWebBrowser" HorizontalAlignment="Left" Height="400" Margin="15" VerticalAlignment="Top" Width="700" /> <TextBlock Text="Please perform OAuth process (above), enter Pin (below) when ready, and tap Authenticate:" Margin="15,15,15,5" /> <TextBox Name="PinTextBox" Margin="15,0,15,15" Width="432" HorizontalAlignment="Left" IsEnabled="False" /> <Button Name="AuthenticatePinButton" Content="Authenticate" Margin="15" IsEnabled="False" Click="AuthenticatePinButton_Click" /> </StackPanel> The WebView in the code above is what allows the user to see the Twitter authentication page. The TextBox is for entering the Pin, and the Button invokes code that will take the Pin and allow LINQ to Twitter to complete the authentication process. As you can see, there are several steps to OAuth authentication, but LINQ to Twitter tries to minimize the amount of code you have to write. The two important parts of the code to make this happen are the part that starts the authentication process and the part that completes the authentication process. The following code, from OAuthPage.xaml.cs, shows a couple events that are instrumental in making this process happen: public OAuthPage() { this.InitializeComponent(); this.Loaded += OAuthPage_Loaded; OAuthWebBrowser.LoadCompleted += OAuthWebBrowser_LoadCompleted; } The OAuthWebBrowser_LoadCompleted event handler enables UI controls when the browser is done loading – notice that the TextBox and Button in the previous XAML have their IsEnabled attributes set to False. When the Page.Loaded event is invoked, the OAuthPage_Loaded handler starts the OAuth process, shown here: void OAuthPage_Loaded(object sender, RoutedEventArgs e) { auth = new PinAuthorizer { Credentials = new InMemoryCredentials { ConsumerKey = "", ConsumerSecret = "" }, UseCompression = true, GoToTwitterAuthorization = pageLink => Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => OAuthWebBrowser.Navigate(new Uri(pageLink, UriKind.Absolute))) }; auth.BeginAuthorize(resp => Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => { switch (resp.Status) { case TwitterErrorStatus.Success: break; case TwitterErrorStatus.RequestProcessingException: case TwitterErrorStatus.TwitterApiError: new MessageDialog(resp.Error.ToString(), resp.Message).ShowAsync(); break; } })); } The PinAuthorizer, auth, a field of this class instantiated in the code above, assigns keys to the Credentials property. These are credentials that come from registering an application with Twitter, explained in the LINQ to Twitter documentation, Securing Your Applications. Notice how I use Dispatcher.RunAsync to marshal the web browser navigation back onto the UI thread. Internally, LINQ to Twitter invokes the lambda expression assigned to GoToTwitterAuthorization when starting the OAuth process.  In this case, we want the WebView control to navigate to the Twitter authentication page, which is defined with a default URL in LINQ to Twitter and passed to the GoToTwitterAuthorization lambda as pageLink. Then you need to start the authorization process by calling BeginAuthorize. This starts the OAuth dance, running asynchronously.  LINQ to Twitter invokes the callback assigned to the BeginAuthorize parameter, allowing you to take whatever action you need, based on the Status of the response, resp. As mentioned earlier, this is where the user performs the authentication process, enters the Pin, and clicks authenticate. The handler for authenticate completes the process and saves the authorizer for subsequent use by the application, as shown below: void AuthenticatePinButton_Click(object sender, RoutedEventArgs e) { auth.CompleteAuthorize( PinTextBox.Text, completeResp => Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () => { switch (completeResp.Status) { case TwitterErrorStatus.Success: SuspensionManager.SessionState["Authorizer"] = auth; Frame.Navigate(typeof(TweetPage)); break; case TwitterErrorStatus.RequestProcessingException: case TwitterErrorStatus.TwitterApiError: new MessageDialog(completeResp.Error.ToString(), completeResp.Message).ShowAsync(); break; } })); } The PinAuthorizer CompleteAuthorize method takes two parameters: Pin and callback. The Pin is from what the user entered in the TextBox prior to clicking the Authenticate button that invoked this method. The callback handles the response from completing the OAuth process. The completeResp holds information about the results of the operation, indicated by a Status property of type TwitterErrorStatus. On success, the code assigns auth to SessionState. You might remember SessionState from the previous description of TweetPage – this is where the valid authorizer comes from. After saving the authorizer, the code navigates the user back to TweetPage, where they can type in a message, click the Tweet button, and observe that they have successfully tweeted. Summary You’ve seen how to get started with using LINQ to Twitter in a Metro-style application. The generated code contained a SuspensionManager class with way to manage information across multiple pages via its SessionState property. You also saw how LINQ to Twitter performs authorization in two steps of starting the process and completing the process when the user provides a Pin number. Remember to marshal callback thread back onto the UI – you saw earlier how to use Dispatcher.RunAsync to accomplish this. There were a few steps in the process, but LINQ to Twitter did minimize the amount of code you needed to write to make it happen. You can download the MetroOAuthDemo.zip sample on the LINQ to Twitter Samples Page.   @JoeMayo

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• Building Enterprise Smartphone App &ndash; Part 4: Application Development Considerations

  - by Tim Murphy

  This is the final part in a series of posts based on a talk I gave recently at the Chicago Information Technology Architects Group.  Feel free to leave feedback. Application Development Considerations Now we get to the actual building of your solutions.  What are the skills and resources that will be needed in order to develop a smartphone application in the enterprise? Language Knowledge One of the first things you need to consider when you are deciding which platform language do you either have the most in house skill base or can you easily acquire.  If you already have developers who know Java or C# you may want to use either Android or Windows Phone.  You should also take into consideration the market availability of developers.  If your key developer leaves how easy is it to find a knowledgeable replacement? A second consideration when it comes to programming languages is the qualities exposed by the languages of a particular platform.  How well does that development language and its associated frameworks support things like security and access to the features of the smartphone hardware?  This will play into your overall cost of ownership if you have to create this infrastructure on your own. Manage Limited Resources Everything is limited on a smartphone: battery, memory, processing power, network bandwidth.  When developing your applications you will have to keep your footprint as small as possible in every way.  This means not running unnecessary processes in the background that will drain the battery or pulling more data over the airwaves than you have to.  You also want to keep your on device in as compact a format as possible. Mobile Design Patterns There are a number of design patterns that have either come to life because of smartphone development or have been adapted for this use.  The main pattern in the Windows Phone environment is the MVVM (Model-View-View-Model).  This is great for overall application structure and separation of concerns.  The fun part is trying to keep that separation as pure as possible.  Many of the other patterns may or may not have strict definitions, but some that you need to be concerned with are push notification, asynchronous communication and offline data storage. Real estate is limited on smartphones and even tablets. You are also limited in the type of controls that can be represented in the UI. This means rethinking how you modularize your application. Typing is also much harder to do so you want to reduce this as much as possible.  This leads to UI patterns.  While not what we would traditionally think of as design patterns the guidance each platform has for UI design is critical to the success of your application.  If user find the application difficult navigate they will not use it. Development Process Because of the differences in development tools required, test devices and certification and deployment processes your teams will need to learn new way of working together.  This will include the need to integrate service contracts of back-end systems with mobile applications.  You will also want to make sure that you present consistency across different access points to corporate data.  Your web site may have more functionality than your smartphone application, but it should have a consistent core set of functionality.  This all requires greater communication between sub-teams of your developers. Testing Process Testing of smartphone apps has a lot more to do with what happens when you lose connectivity or if the user navigates away from your application. There are a lot more opportunities for the user or the device to perform disruptive acts.  This should be your main testing concentration aside from the main business requirements.  You will need to do things like setting the phone to airplane mode and seeing what the application does in order to weed out any gaps in your handling communication interruptions. Need For Outside Experts Since this is a development area that is new to most companies the need for experts is a lot greater. Whether these are consultants, vendor representatives or just development community forums you will need to establish expert contacts. Nothing is more dangerous for your project timelines than a lack of knowledge.  Make sure you know who to call to avoid lengthy delays in your project because of knowledge gaps. Security Security has to be a major concern for enterprise applications. You aren't dealing with just someone's game standings. You are dealing with a companies intellectual property and competitive advantage. As such you need to start by limiting access to the application itself.  Once the user is in the app you need to ensure that the data is secure at all times.  This includes both local storage and across the wire.  This means if a platform doesn’t natively support encryption for these functions you will need to find alternatives to secure your data.  You also need to keep secret (encryption) keys obfuscated or locked away outside of the application. People can disassemble the code otherwise and break your encryption. Offline Capabilities As we discussed earlier one your biggest concerns is not having connectivity.  Because of this a good portion of your code may be dedicated to handling loss of connection and reconnection situations.  What do you do if you lose the network?  Back up all your transactions and store of any supporting data so that operations can continue off line. In order to support this you will need to determine the available flat file or local data base capabilities of the platform.  Any failed transactions will need to support a retry mechanism whether it is automatic or user initiated.  This also includes your services since they will need to be able to roll back partially completed transactions.  What ever you do, don’t ignore this area when you are designing your system. Deployment Each platform has different deployment capabilities. Some are more suited to enterprise situations than others. Apple's approach is probably the most mature at the moment. Prior to the current generation of smartphone platforms it would have been Windows CE. Windows Phone 7 has the limitation that the app has to be distributed through the same network as public facing applications. You mark them as private which means that they are only accessible by a direct URL. Unfortunately this does not make them undiscoverable (although it is very difficult). This will change with Windows Phone 8 where companies will be able to certify their own applications and distribute them.  Given this Windows Phone applications need to be more diligent with application access in order to keep them restricted to the company's employees. My understanding of the Android deployment schemes is that it is much less standardized then either iOS or Windows Phone. Someone would have to confirm or deny that for me though since I have not yet put the time into researching this platform further. Given my limited exposure to the iOS and Android platforms I have not been able to confirm this, but there are varying degrees of user involvement to install and keep applications updated. At one extreme the user just goes to a website to do the install and in other case they may need to download files and perform steps to install them. Future Bluetooth Today we use Bluetooth for keyboards, mice and headsets.  In the future it could be used to interrogate car computers or manufacturing systems or possibly retail machines by service techs.  This would open smartphones to greater use as a almost a Star Trek Tricorder.  You would get you all your data as well as being able to use it as a universal remote for just about any device or machine. Better corporation controlled deployment At least in the Windows Phone world the upcoming release of Windows Phone 8 will include a private certification and deployment option that is currently not available with Windows Phone 7 (Mango). We currently have to run the apps through the Marketplace certification process and use a targeted distribution method. Platform independent approaches HTML5 and JavaScript with Web Service has become a popular topic lately for not only creating flexible web site, but also creating cross platform mobile applications.  I’m not yet convinced that this lowest common denominator approach is viable in most cases, but it does have it’s place and seems to be growing.  Be sure to keep an eye on it. Summary From my perspective enterprise smartphone applications can offer a great competitive advantage to many companies.  They are not cheap to build and should be approached cautiously.  Understand the factors I have outlined in this series, do you due diligence and see if there is a portion of your business that can benefit from the mobile experience. del.icio.us Tags: Architecture,Smartphones,Windows Phone,iOS,Android

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• What is bondib1 used for on SPARC SuperCluster with InfiniBand, Solaris 11 networking & Oracle RAC?

  - by user12620111

  A co-worker asked the following question about a SPARC SuperCluster InfiniBand network: > on the database nodes the RAC nodes communicate over the cluster_interconnect. This is the > 192.168.10.0 network on bondib0. (according to ./crs/install/crsconfig_params NETWORKS> setting) > What is bondib1 used for? Is it a HA counterpart in case bondib0 dies? This is my response: Summary: bondib1 is currently only being used for outbound cluster interconnect interconnect traffic. Details: bondib0 is the cluster_interconnect $ oifcfg getif            bondeth0  10.129.184.0  global  public bondib0  192.168.10.0  global  cluster_interconnect ipmpapp0  192.168.30.0  global  public bondib0 and bondib1 are on 192.168.10.1 and 192.168.10.2 respectively. # ipadm show-addr | grep bondi bondib0/v4static  static   ok           192.168.10.1/24 bondib1/v4static  static   ok           192.168.10.2/24 Hostnames tied to the IPs are node1-priv1 and node1-priv2  # grep 192.168.10 /etc/hosts 192.168.10.1    node1-priv1.us.oracle.com   node1-priv1 192.168.10.2    node1-priv2.us.oracle.com   node1-priv2 For the 4 node RAC interconnect: Each node has 2 private IP address on the 192.168.10.0 network. Each IP address has an active InfiniBand link and a failover InfiniBand link. Thus, the 4 node RAC interconnect is using a total of 8 IP addresses and 16 InfiniBand links. bondib1 isn't being used for the Virtual IP (VIP): $ srvctl config vip -n node1 VIP exists: /node1-ib-vip/192.168.30.25/192.168.30.0/255.255.255.0/ipmpapp0, hosting node node1 VIP exists: /node1-vip/10.55.184.15/10.55.184.0/255.255.255.0/bondeth0, hosting node node1 bondib1 is on bondib1_0 and fails over to bondib1_1: # ipmpstat -g GROUP       GROUPNAME   STATE     FDT       INTERFACES ipmpapp0    ipmpapp0    ok        --        ipmpapp_0 (ipmpapp_1) bondeth0    bondeth0    degraded  --        net2 [net5] bondib1     bondib1     ok        --        bondib1_0 (bondib1_1) bondib0     bondib0     ok        --        bondib0_0 (bondib0_1) bondib1_0 goes over net24 # dladm show-link | grep bond LINK                CLASS     MTU    STATE    OVER bondib0_0           part      65520  up       net21 bondib0_1           part      65520  up       net22 bondib1_0           part      65520  up       net24 bondib1_1           part      65520  up       net23 net24 is IB Partition FFFF # dladm show-ib LINK         HCAGUID         PORTGUID        PORT STATE  PKEYS net24        21280001A1868A  21280001A1868C  2    up     FFFF net22        21280001CEBBDE  21280001CEBBE0  2    up     FFFF,8503 net23        21280001A1868A  21280001A1868B  1    up     FFFF,8503 net21        21280001CEBBDE  21280001CEBBDF  1    up     FFFF On Express Module 9 port 2: # dladm show-phys -L LINK              DEVICE       LOC net21             ibp4         PCI-EM1/PORT1 net22             ibp5         PCI-EM1/PORT2 net23             ibp6         PCI-EM9/PORT1 net24             ibp7         PCI-EM9/PORT2 Outbound traffic on the 192.168.10.0 network will be multiplexed between bondib0 & bondib1 # netstat -rn Routing Table: IPv4   Destination           Gateway           Flags  Ref     Use     Interface -------------------- -------------------- ----- ----- ---------- --------- 192.168.10.0         192.168.10.2         U        16    6551834 bondib1   192.168.10.0         192.168.10.1         U         9    5708924 bondib0   There is a lot more traffic on bondib0 than bondib1 # /bin/time snoop -I bondib0 -c 100 > /dev/null Using device ipnet/bondib0 (promiscuous mode) 100 packets captured real        4.3 user        0.0 sys         0.0 (100 packets in 4.3 seconds = 23.3 pkts/sec) # /bin/time snoop -I bondib1 -c 100 > /dev/null Using device ipnet/bondib1 (promiscuous mode) 100 packets captured real       13.3 user        0.0 sys         0.0 (100 packets in 13.3 seconds = 7.5 pkts/sec) Half of the packets on bondib0 are outbound (from self). The remaining packet are split evenly, from the other nodes in the cluster. # snoop -I bondib0 -c 100 | awk '{print $1}' | sort | uniq -c Using device ipnet/bondib0 (promiscuous mode) 100 packets captured   49 node1-priv1.us.oracle.com   24 node2-priv1.us.oracle.com   14 node3-priv1.us.oracle.com   13 node4-priv1.us.oracle.com 100% of the packets on bondib1 are outbound (from self), but the headers in the packets indicate that they are from the IP address associated with bondib0: # snoop -I bondib1 -c 100 | awk '{print $1}' | sort | uniq -c Using device ipnet/bondib1 (promiscuous mode) 100 packets captured  100 node1-priv1.us.oracle.com The destination of the bondib1 outbound packets are split evenly, to node3 and node 4. # snoop -I bondib1 -c 100 | awk '{print $3}' | sort | uniq -c Using device ipnet/bondib1 (promiscuous mode) 100 packets captured   51 node3-priv1.us.oracle.com   49 node4-priv1.us.oracle.com Conclusion: bondib1 is currently only being used for outbound cluster interconnect interconnect traffic.

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• Project Jigsaw: Late for the train: The Q&A

  - by Mark Reinhold

  I recently proposed, to the Java community in general and to the SE 8 (JSR 337) Expert Group in particular, to defer Project Jigsaw from Java 8 to Java 9. I also proposed to aim explicitly for a regular two-year release cycle going forward. Herewith a summary of the key questions I’ve seen in reaction to these proposals, along with answers. Making the decision Q Has the Java SE 8 Expert Group decided whether to defer the addition of a module system and the modularization of the Platform to Java SE 9? A No, it has not yet decided. Q By when do you expect the EG to make this decision? A In the next month or so. Q How can I make sure my voice is heard? A The EG will consider all relevant input from the wider community. If you have a prominent blog, column, or other communication channel then there’s a good chance that we’ve already seen your opinion. If not, you’re welcome to send it to the Java SE 8 Comments List, which is the EG’s official feedback channel. Q What’s the overall tone of the feedback you’ve received? A The feedback has been about evenly divided as to whether Java 8 should be delayed for Jigsaw, Jigsaw should be deferred to Java 9, or some other, usually less-realistic, option should be taken. Project Jigsaw Q Why is Project Jigsaw taking so long? A Project Jigsaw started at Sun, way back in August 2008. Like many efforts during the final years of Sun, it was not well staffed. Jigsaw initially ran on a shoestring, with just a handful of mostly part-time engineers, so progress was slow. During the integration of Sun into Oracle all work on Jigsaw was halted for a time, but it was eventually resumed after a thorough consideration of the alternatives. Project Jigsaw was really only fully staffed about a year ago, around the time that Java 7 shipped. We’ve added a few more engineers to the team since then, but that can’t make up for the inadequate initial staffing and the time lost during the transition. Q So it’s really just a matter of staffing limitations and corporate-integration distractions? A Aside from these difficulties, the other main factor in the duration of the project is the sheer technical difficulty of modularizing the JDK. Q Why is modularizing the JDK so hard? A There are two main reasons. The first is that the JDK code base is deeply interconnected at both the API and the implementation levels, having been built over many years primarily in the style of a monolithic software system. We’ve spent considerable effort eliminating or at least simplifying as many API and implementation dependences as possible, so that both the Platform and its implementations can be presented as a coherent set of interdependent modules, but some particularly thorny cases remain. Q What’s the second reason? A We want to maintain as much compatibility with prior releases as possible, most especially for existing classpath-based applications but also, to the extent feasible, for applications composed of modules. Q Is modularizing the JDK even necessary? Can’t you just put it in one big module? A Modularizing the JDK, and more specifically modularizing the Java SE Platform, will enable standard yet flexible Java runtime configurations scaling from large servers down to small embedded devices. In the long term it will enable the convergence of Java SE with the higher-end Java ME Platforms. Q Is Project Jigsaw just about modularizing the JDK? A As originally conceived, Project Jigsaw was indeed focused primarily upon modularizing the JDK. The growing demand for a truly standard module system for the Java Platform, which could be used not just for the Platform itself but also for libraries and applications built on top of it, later motivated expanding the scope of the effort. Q As a developer, why should I care about Project Jigsaw? A The introduction of a modular Java Platform will, in the long term, fundamentally change the way that Java implementations, libraries, frameworks, tools, and applications are designed, built, and deployed. Q How much progress has Project Jigsaw made? A We’ve actually made a lot of progress. Much of the core functionality of the module system has been prototyped and works at both compile time and run time. We’ve extended the Java programming language with module declarations, worked out a structure for modular source trees and corresponding compiled-class trees, and implemented these features in javac. We’ve defined an efficient module-file format, extended the JVM to bootstrap a modular JRE, and designed and implemented a preliminary API. We’ve used the module system to make a good first cut at dividing the JDK and the Java SE API into a coherent set of modules. Among other things, we’re currently working to retrofit the java.util.ServiceLoader API to support modular services. Q I want to help! How can I get involved? A Check out the project page, read the draft requirements and design overview documents, download the latest prototype build, and play with it. You can tell us what you think, and follow the rest of our work in real time, on the jigsaw-dev list. The Java Platform Module System JSR Q What’s the relationship between Project Jigsaw and the eventual Java Platform Module System JSR? A At a high level, Project Jigsaw has two phases. In the first phase we’re exploring an approach to modularity that’s markedly different from that of existing Java modularity solutions. We’ve assumed that we can change the Java programming language, the virtual machine, and the APIs. Doing so enables a design which can strongly enforce module boundaries in all program phases, from compilation to deployment to execution. That, in turn, leads to better usability, diagnosability, security, and performance. The ultimate goal of the first phase is produce a working prototype which can inform the work of the Module-System JSR EG. Q What will happen in the second phase of Project Jigsaw? A The second phase will produce the reference implementation of the specification created by the Module-System JSR EG. The EG might ultimately choose an entirely different approach than the one we’re exploring now. If and when that happens then Project Jigsaw will change course as necessary, but either way I think that the end result will be better for having been informed by our current work. Maven & OSGi Q Why not just use Maven? A Maven is a software project management and comprehension tool. As such it can be seen as a kind of build-time module system but, by its nature, it does nothing to support modularity at run time. Q Why not just adopt OSGi? A OSGi is a rich dynamic component system which includes not just a module system but also a life-cycle model and a dynamic service registry. The latter two facilities are useful to some kinds of sophisticated applications, but I don’t think they’re of wide enough interest to be standardized as part of the Java SE Platform. Q Okay, then why not just adopt the module layer of OSGi? A The OSGi module layer is not operative at compile time; it only addresses modularity during packaging, deployment, and execution. As it stands, moreover, it’s useful for library and application modules but, since it’s built strictly on top of the Java SE Platform, it can’t be used to modularize the Platform itself. Q If Maven addresses modularity at build time, and the OSGi module layer addresses modularity during deployment and at run time, then why not just use the two together, as many developers already do? A The combination of Maven and OSGi is certainly very useful in practice today. These systems have, however, been built on top of the existing Java platform; they have not been able to change the platform itself. This means, among other things, that module boundaries are weakly enforced, if at all, which makes it difficult to diagnose configuration errors and impossible to run untrusted code securely. The prototype Jigsaw module system, by contrast, aims to define a platform-level solution which extends both the language and the JVM in order to enforce module boundaries strongly and uniformly in all program phases. Q If the EG chooses an approach like the one currently being taken in the Jigsaw prototype, will Maven and OSGi be made obsolete? A No, not at all! No matter what approach is taken, to ensure wide adoption it’s essential that the standard Java Platform Module System interact well with Maven. Applications that depend upon the sophisticated features of OSGi will no doubt continue to use OSGi, so it’s critical that implementations of OSGi be able to run on top of the Java module system and, if suitably modified, support OSGi bundles that depend upon Java modules. Ideas for how to do that are currently being explored in Project Penrose. Java 8 & Java 9 Q Without Jigsaw, won’t Java 8 be a pretty boring release? A No, far from it! It’s still slated to include the widely-anticipated Project Lambda (JSR 335), work on which has been going very well, along with the new Date/Time API (JSR 310), Type Annotations (JSR 308), and a set of smaller features already in progress. Q Won’t deferring Jigsaw to Java 9 delay the eventual convergence of the higher-end Java ME Platforms with Java SE? A It will slow that transition, but it will not stop it. To allow progress toward that convergence to be made with Java 8 I’ve suggested to the Java SE 8 EG that we consider specifying a small number of Profiles which would allow compact configurations of the SE Platform to be built and deployed. Q If Jigsaw is deferred to Java 9, would the Oracle engineers currently working on it be reassigned to other Java 8 features and then return to working on Jigsaw again after Java 8 ships? A No, these engineers would continue to work primarily on Jigsaw from now until Java 9 ships. Q Why not drop Lambda and finish Jigsaw instead? A Even if the engineers currently working on Lambda could instantly switch over to Jigsaw and immediately become productive—which of course they can’t—there are less than nine months remaining in the Java 8 schedule for work on major features. That’s just not enough time for the broad review, testing, and feedback which such a fundamental change to the Java Platform requires. Q Why not ship the module system in Java 8, and then modularize the platform in Java 9? A If we deliver a module system in one release but don’t use it to modularize the JDK until some later release then we run a big risk of getting something fundamentally wrong. If that happens then we’d have to fix it in the later release, and fixing fundamental design flaws after the fact almost always leads to a poor end result. Q Why not ship Jigsaw in an 8.5 release, less than two years after 8? Or why not just ship a new release every year, rather than every other year? A Many more developers work on the JDK today than a couple of years ago, both because Oracle has dramatically increased its own investment and because other organizations and individuals have joined the OpenJDK Community. Collectively we don’t, however, have the bandwidth required to ship and then provide long-term support for a big JDK release more frequently than about every other year. Q What’s the feedback been on the two-year release-cycle proposal? A For just about every comment that we should release more frequently, so that new features are available sooner, there’s been another asking for an even slower release cycle so that large teams of enterprise developers who ship mission-critical applications have a chance to migrate at a comfortable pace.

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