In my current project, I've been helping a client develop a native iOS app for their customers. It's written mostly in Objective-C and talks to a REST API. I talked about how we documented our REST API a couple days ago. We developed a prototype for this application back in December, using AngularJS and Bootstrap. Rather than using PhoneGap, we loaded our app in a UIWebView. It all seemed to work well until we needed to read an activation code with the device's camera. Since we didn't know how to do OCR in JavaScript, we figured a mostly-native app was the way to go. We hired an outside company to do iOS development in January and they've been developing the app since the beginning of February. In the last couple weeks, we encountered some screens that seemed fitting for HTML5, so we turned back to our AngularJS prototype. The prototype used Bootstrap heavily, but we quickly learned it didn't look like an iOS 7 app, which is what our UX Designer requested. A co-worker pointed out Ionic, developed by Drifty. It's basically Bootstrap for Native, so the apps you develop look and behave like a mobile application. What is Ionic? Free and open source, Ionic offers a library of mobile-optimized HTML, CSS and JS components for building highly interactive apps. Built with Sass and optimized for AngularJS. I started developing with Ionic a few weeks ago. Using its CSS classes and AngularJS directives, I was able to create several new screens in a matter of days. Most of the time, I was learning new things: how to override its back button behavior (to launch back into the native app), how to configure routes with ui-router, and how to make the $ionicLoading service look native. Now that I know a lot of the basics, I feel like I can really crank out some code. Tip: I learned how subviews work with ui-router thanks to a YouTube video of Tim Kindberg on Angular UI-Router. However, subviews never fully made sense until I saw Jared Bell's diagram. To demonstrate how easy it is to use Ionic, I whipped up a quick example application. You can get the source on GitHub at https://github.com/mraible/boot-ionic. The app is a refactored version of Josh Long's x-auth-security that uses Ionic instead of raw AngularJS and Bootstrap. To keep things simple, I did not develop the native app that wraps the HTML. Below are the steps I used to convert from AngularJS + Bootstrap to Ionic. If you want to convert a simple AngularJS app to use Ionic, hopefully this will help. 1. Download Ionic and add it to your project. Ionic 1.0 Beta was released earlier this week. You can download it from here. Add its files to your project. In this example, I added them to src/main/resources/public. In my index.html, I removed Bootstrap's CSS and replaced it with Ionic's. - + - + Next, I replaced Angular, Bootstrap and jQuery's JavaScript references. - - - + - What about WebJars? You might ask - why not use WebJars? You can, once this pull request is accepted and an updated version is deployed to Maven central. Here's how the application would change. 2. Change from Angular's Router to ui-router. Ionic uses ui-router for matching URLs and loading particular pages. The raw Angular routing looks pretty similar to how it does with ui-router, except it uses a $stateProvider service instead of $routeProvider. You'll notice I also added 'ionic' as a dependency. -angular.module('exampleApp', ['ngRoute', 'ngCookies', 'exampleApp.services']) +angular.module('exampleApp', ['ionic', 'ngCookies', 'exampleApp.services']) .config( - [ '$routeProvider', '$locationProvider', '$httpProvider', function($routeProvider, $locationProvider, $httpProvider) { + [ '$stateProvider', '$urlRouterProvider', '$httpProvider', function($stateProvider, $urlRouterProvider, $httpProvider) { - $routeProvider.when('/create', { templateUrl: 'partials/create.html', controller: CreateController}); + $stateProvider.state('create', {url: '/create', templateUrl: 'partials/create.html', controller: CreateController}) + .state('edit', {url: '/edit/:id', templateUrl: 'partials/edit.html', controller: EditController}) + .state('login', {url: '/login', templateUrl: 'partials/login.html', controller: LoginController}) + .state('index', {url: '/index', templateUrl: 'partials/index.html', controller: IndexController}); - $routeProvider.when('/edit/:id', { templateUrl: 'partials/edit.html', controller: EditController}); - $routeProvider.when('/login', { templateUrl: 'partials/login.html', controller: LoginController}); - $routeProvider.otherwise({templateUrl: 'partials/index.html', controller: IndexController}); - - $locationProvider.hashPrefix('!'); + $urlRouterProvider.otherwise('/index'); 3. Add Ionic elements to your index.html. In contrast to Bootstrap's navbar, Ionic has header and footer elements. Rather than using a ng-view directive, you use an . It's a pretty slick setup once you understand it, especially since they allow you to easily override back-button behavior and nav buttons. - - - - - - {{error} - - + + + {{error} + + + + Logout + + 4. Change your templates to use and . After routes are migrated and basic navigation is working, you'll need to modify your templates to use and . Here's a diff from the most complicated page in the app. - - Create - - - News - + + + + + + + + + + - - - - Remove - Edit - - {{newsEntry.date | date} - {{newsEntry.content} - - + + + {{newsEntry.date | date} + {{newsEntry.content} + + + + I did migrate to use an with delete/options buttons, so some additional JavaScript changes were needed. -function IndexController($scope, NewsService) { +function IndexController($scope, $state, NewsService) { $scope.newsEntries = NewsService.query(); + $scope.data = { + showDelete: false + }; + $scope.deleteEntry = function(newsEntry) { newsEntry.$remove(function() { $scope.newsEntries = NewsService.query(); }); }; + + $scope.itemButtons = [{ + text: 'Edit', + type: 'button-assertive', + onTap: function (item) { + $state.go('edit', {id: item.id}); + } + }]; } Screenshots After making all these changes, the app looks pretty good in Chrome. Tips and Tricks In additional to figuring out how to use Ionic, I discovered a few other tidbits along the way. First of all, we had a different default color for the header. Since Ionic uses generic color names (e.g. light, stable, positive, calm), I found it easy to change the default value for "positive" and then continue to use their class names. Modifying CSS variable colors To modify the base color for "positive", I cloned the source, and modified scss/_variables.scss. $light: #fff !default; $stable: #f8f8f8 !default; -$positive: #4a87ee !default; +$positive: #589199 !default; $calm: #43cee6 !default; $balanced: #66cc33 !default; $energized: #f0b840 !default; After making this change, I ran "grunt" and copied dist/css/ionic.css into our project. iOS Native Integration Our app uses a similar token-based authentication mechanism as x-auth-security, except its backed by Crowd. However, since users won't be logging directly into the Ionic app, we added the "else" clause in app.js to allow a token to be passed in via URL. We also allowed the backend API path to be overridden. /* Try getting valid user from cookie or go to login page */ var originalPath = $location.path(); $location.path("/login"); var user = $cookieStore.get('user'); if (user !== undefined) { $rootScope.user = user; $http.defaults.headers.common[xAuthTokenHeaderName] = user.token; $location.path(originalPath); } else { // token passed in from native app var authToken = $location.search().token; if (authToken) { $http.defaults.headers.common['X-Auth-Token'] = authToken; } } // allow overriding the base API path $rootScope.apiPath = '/api/v1.0'; if ($location.search().apiPath) { $rootScope.apiPath = $location.search().apiPath; } By adding this logic, the iOS app can pull up any particular page in a webview and let the Ionic app talk to the API. Here's what the Objective-C code looks like: NSString *versionNumber = @"v1.0"; NSString *apiPath = @"https://server.com/api/"; NSString *authToken = [TemporaryDataStore sharedInstance].authToken; // webapp is a symbolic link to the Ionic app, created with Angular Seed NSString *htmlFilePath = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html" inDirectory:@"webapp/app"]; // Note: We need to do it this way because 'fileURLWithPath:' would encode the '#' to '%23" which breaks the html page NSURL *htmlFileURL = [NSURL fileURLWithPath:htmlFilePath]; NSString *webappURLPath = [NSString stringWithFormat:@"%@#/news?apiPath=%@%@&token=%@", htmlFileURL.absoluteString, apiPath, versionNumber, authToken]; // Now convert the string to a URL (doesn't seem to encode the '#' this way) NSURL *webappURL = [NSURL URLWithString:webappURLPath]; [super updateWithURL:webappURL]; We also had to write some logic to navigate back to the native app. We used a custom URL scheme to do this, and the Ionic app simply called it. To override the default back button, I added an "ng-controller" attribute to and added a custom back button. To detect if the app was loaded by iOS (vs. a browser, which we tested in), we used the following logic: // set native app indicator if (document.location.toString().indexOf('appName.app') > -1) { $rootScope.isNative = true; } Our Ionic app has three entry points, defined by "stateName1", "stateName2" and "stateName3" in this example. The code for our NavController handles navigating back normally (when in a browser) or back to the native app. The "appName" reference below is a 3-letter acronym we used for our app. .controller('NavController', function($scope, $ionicNavBarDelegate, $state) { $scope.goBack = function() { if ($scope.isNative && backToNative($state)) { location.href='appName-ios://back'; } else { $ionicNavBarDelegate.back(); } }; function backToNative($state) { var entryPoints = ['stateName1', 'stateName2', 'stateName3']; return entryPoints.some(function (entry) { return $state.current === $state.get(entry); }); } }) Summary I've enjoyed working with Ionic over the last month. The biggest change I've had to make to our AngularJS app has been to integrate ui-router. Apart from this, the JavaScript didn't change much. However, the HTML had to change quite a bit. As far as CSS is concerned, I found myself tweaking things to fit our designs, but less so than I did with Bootstrap. When I've run into issues with Ionic, the community has been very helpful on their forum. It's the first forum I've used that's powered by Discourse, and I dig it. You can find the source from this article in my boot-ionic project. Clone it and run "mvn spring-boot:run", then open http://localhost:8080. If you're looking to create a native app using HTML5 technologies, I highly recommend you take a look at Ionic. We're glad we did. Angular 2.0 will target mobile apps and Ionic is already making them look pretty damn good.

Usually if I concentrate I am able to understand most SQL statements. There are times though such as: When a set of tables is not familiar When I did not write the SQL statement When the SQL statement is long and involves many tables and joins When I want to discuss a statement with a colleague All of the above Having a visual representation of a SQL statement can be helpful in deciphering the statement. My visualisation tool of choice for SQL is an Open Source application called Reverse Snowflake Joins (REVJ). As the name implies, this tool shines when it comes to showing you how your tables are related. I have installed the tool on my workstation but when I am on the move I use the online version of the tool. Using the tool is straight forward, simply paste your SQL statement in the text area and generate the diagram, the online version generates an SVG image. I have at times found that the tool struggles with complex CASE statements. In such cases I remove the CASE statement and just include the fields used in the case statement. Below is a sample statement to show REVJ at work. SELECT a.prod_cat_name ,b.prod_name ,c.prod_owner_name ,p.promo_id ,pt.promo_type ,sum(s.units) as total_units ,sum(s.sale_price) as total_sale_price ,sum(prev_s.units) as prev_yr_total_units FROM product_category a JOIN product b ON a.product_cat_id = b.product_cat_id LEFT OUTER JOIN product_owner c ON a.product_cat_id = c.product_cat_id JOIN sales s ON b.product_id = s.product_id JOIN sales prev_s ON s.sale_year = prev_s.sale_year-1 LEFT OUTER JOIN promotion p ON s.promo_id = p.promo_id RIGHT OUTER JOIN promo_type pt ON p.promo_type_id = pt.promo_type_id WHERE pt.promo_type IN ('Email', 'TV') AND a.prod_cat_name = 'Electronics' AND s.sale_year >=2013 GROUP BY a.prod_cat_name ,b.prod_name ,c.prod_owner_name ,p.promo_id ,pt.promo_type HAVING sum(s.units)>100 The generated image shown below. Notice how the filters applied to each table are also shown, further simplifying the task of understanding the SQL statement. For more complex examples have a look at big samples page.

To convert a byte[] array to a String we can simply use the new String(byte[]) constructor. But if the array contains non-printable bytes we don't get a good representation. In Groovy we can use the method encodeHex() to transform a byte[] array to a hex String value. The byteelements are converted to their hexadecimal equivalents. final byte[] printable = [109, 114, 104, 97, 107, 105] // array with non-printable bytes 6, 27 (ACK, ESC) final byte[] nonprintable = [109, 114, 6, 27, 104, 97, 107, 105] assert new String(printable) == 'mrhaki' assert new String(nonprintable) != 'mr haki' // encodeHex() returns a Writable final Writable printableHex = printable.encodeHex() assert printableHex.toString() == '6d7268616b69' final nonprintableHex = nonprintable.encodeHex().toString() assert nonprintableHex == '6d72061b68616b69' // Convert back assert nonprintableHex.decodeHex() == nonprintable Code written with Groovy 2.2.1

I’m going to start by discussing the Spring WebMVC configuration to compile and run Java without an IDE.

Java is the most widely used language in the world ([citation needed]), and everyone has an opinion about it. Due to it being mainstream, it is usually mocked, and sometimes rightly so, but sometimes the criticism just doesn’t touch reality. I’ll try to explain my favorite 5 misconceptions about Java. Java is slow – that might have been true for Java 1.0, and initially may sounds logical, since java is not compiled to binary, but to bytecode, which is in turn interpreted. However, modern versions of the JVM are very, very optimized (JVM optimizations is a topic worth not just an article, but a whole book) and this is no longer remotely true. As noted here, Java is even on-par with C++ in some cases. And it is certainly not a good idea to make a joke about Java being slow if you are a Ruby or PHP developer. Java is too verbose – here we need to split the language from the SDK and from other libraries. There is some verbosity in the JDK (e.g. java.io), which is: 1. easily overcome with de-facto standard libraries like guava 2. a good thing As for language verbosity, the only reasonable point were anonymous classes. Which are no longer an issue in Java 8 with the the functional additions. Getters and setters, Foo foo = new Foo() instead of using val – that is (possibly) boilerplate, but it’s not verbose – it doesn’t add conceptual weight to the code. It doesn’t take more time to write, read or understand. Other libraries – it is indeed pretty scary to see a class like AbstractCommonAsyncFacadeFactoryManagerImpl. But that has nothing to do with Java. It can be argued that sometimes these long names make sense, it can also be argued that they are as complex because the underlying abstraction is unnecessarily complicated, but either way, it is a design decision taken per-library, and nothing that the language or the SDK impose per-se. It is common to see overengineered stuff, but Java in no way pushes you in that direction – stuff can be done in a simple way with any language. You can certainly have AbstractCommonAsyncFacadeFactoryManagerImpl in Ruby, just there wasn’t a stupid architect that thought it’s a good idea and who uses Ruby. If “big, serious, heavy” companies were using Ruby, I bet we’d see the same. Enterprise Java frameworks are bloatware – that was certainly true back in 2002 when EJB 2 was in use (or “has been”, I’m too young to remember). And there are still some overengineered and bloated application servers that you don’t really need. The fact that people are using them is their own problem. You can have a perfectly nice, readable, easy to configure and deploy web application with a framework like Spring, Guice or even CDI; with a web framework like Spring-MVC, Play, Wicket, and even the latest JSF. Or even without any framework, if you feel like you don’t want to reuse the evolved-through-real-world-use frameworks. You can have an application using a message queue, a NoSQL and a SQL database, Amazon S3 file storage, and whatnot, without any accidental complexity. It’s true that people still like to overeingineer stuff, and add a couple of layers where they are not needed, but the fact that frameworks give you this ability doesn’t mean they make you do it. For example, here’s an application that crawls government documents, indexes them, and provides a UI for searching and subscribing. Sounds sort-of simple, and it is. It is written in Scala (in a very java way), but uses only java frameworks – spring, spring-mvc, lucene, jackson, guava. I guess you can start maintaining pretty fast, because it is straightforward. You can’t prototype quickly with Java – this is sort-of related to the previous point – it is assumed that working with Java is slow, and that’s why if you are a startup, or a weekend/hackathon project, you should use Ruby (with Rails), Python, Node JS or anything else that allows you to quickly prototype, to save & refresh, to painlessly iterate. Well, that is simply not true, and I don’t know even where it comes from. Maybe from the fact that big companies with heavy processes use Java, and so making a java app is taking more time. And Save-and-Refresh might look daunting to a beginner, but anyone who has programmed in Java (for the web) for a while, has to know a way to automate that (otherwise he’s a n00b, right?). I’ve summarized the possible approaches, and all of them are mostly OK. Another example here (which may be used as an example for the above point as well) – I made did this project for verifying secure password storage of websites within a weekend + 1 day to fix stuff in the evening. Including the security research. Spring-MVC, JSP templates, MongoDB. Again – quick and easy. You can do nothing in Java without an IDE – of course you can – you can use notepad++, vim, emacs. You will just lack refactoring, compile-on-save, call hierarchies. It would be just like programming in PHP or Python or javascript. The IDE vs Editor debate is a long one, but you can use Java without an IDE. It just doesn’t make sense to do so, because you get so much more from the IDE than from a text editor + command line tools. You may argue that I’m able to write nice and simple java applications quickly because I have a lot of experience, I know precisely which tools to use (and which not) and that I’m of some rare breed of developers with common sense. And while I’ll be flattered by that, I am no different than the good Ruby developer or the Python guru you may be. It’s just that java is too widespread to have only good developers and tools. if so many people were using other language, then probably the same amount of crappy code would’ve been generated. (And PHP is already way ahead even with less usage). I’m the last person not to laugh on jokes about Java, and it certainly isn’t the silver bullet language, but I’d be happier if people had less misconceptions either because of anecdotal evidence, or due to previous bad experience a-la “I hate Java since my previous company where the project was very bloated”. Not only because I don’t like people being biased, but because you may start your next project with a language that will not work, just because you’ve heard “Java is bad”.

Docker is a lightweight virtualization technology for Linux that promises to revolutionize the deployment and management of distributed applications. Rather than requiring a complete operating system, like a traditional virtual machine, Docker is built on top of Linux containers, a feature of the Linux kernel, that allows light-weight Docker containers to share a common kernel while isolating applications and their dependencies. There’s a very good Docker SlideShare presentation here that explains the philosophy behind Docker using the analogy of standardized shipping containers. Interesting that the standard shipping container has done more to create our global economy than all the free-trade treaties and international agreements put together. A Docker image is built from a script, called a ‘Dockerfile’. Each Dockerfile starts by declaring a parent image. This is very cool, because it means that you can build up your infrastructure from a layer of images, starting with general, platform images and then layering successively more application specific images on top. I’m going to demonstrate this by first building an image that provides a Mono development environment, and then creating a simple ‘Hello World’ console application image that runs on top of it. Because the Dockerfiles are simple text files, you can keep them under source control and version your environment and dependencies alongside the actual source code of your software. This is a game changer for the deployment and management of distributed systems. Imagine developing an upgrade to your software that includes new versions of its dependencies, including pieces that we’ve traditionally considered the realm of the environment, and not something that you would normally put in your source repository, like the Mono version that the software runs on for example. You can script all these changes in your Dockerfile, test the new container on your local machine, then simply move the image to test and then production. The possibilities for vastly simplified deployment workflows are obvious. Docker brings concerns that were previously the responsibility of an organization’s operations department and makes them a first class part of the software development lifecycle. Now your infrastructure can be maintained as source code, built as part of your CI cycle and continuously deployed, just like the software that runs inside it. Docker also provides docker index, an online repository of docker images. Anyone can create an image and add it to the index and there are already images for almost any piece of infrastructure you can imagine. Say you want to use RabbitMQ, all you have to do is grab a handy RabbitMQ images such as https://index.docker.io/u/tutum/rabbitmq/ and run it like this: docker run -d -p 5672:5672 -p 55672:55672 tutum/rabbitmq The –p flag maps ports between the image and the host. Let’s look at an example. I’m going to show you how to create a docker image for the Mono development environment and have it built and hosted on the docker index. Then I’m going to build a local docker image for a simple ‘hello world’ console application that I can run on my Ubuntu box. First we need to create a Docker file for our Mono environment. I’m going to use the Mono debian packages from directhex. These are maintained by the official Debian/Ubuntu Mono team and are the recommended way of installing the latest Mono versions on Ubuntu. Here’s the Dockerfile: #DOCKER-VERSION 0.9.1 # #VERSION 0.1 # # monoxide mono-devel package on Ubuntu 13.10 FROM ubuntu:13.10 MAINTAINER Mike Hadlow RUN sudo DEBIAN_FRONTEND=noninteractive apt-get install -y -q software-properties-common RUN sudo add-apt-repository ppa:directhex/monoxide -y RUN sudo apt-get update RUN sudo DEBIAN_FRONTEND=noninteractive apt-get install -y -q mono-devel Notice the first line (after the comments) that reads, ‘FROM ubuntu:13.10’. This specifies the parent image for this Dockerfile. This is the official docker Ubuntu image from the index. When I build this Dockerfile, that image will be automatically downloaded and used as the starting point for my image. But I don’t want to build this image locally. Docker provide a build server linked to the docker index. All you have to do is create a public GitHub repository containing your dockerfile, then link the repository to your profile on docker index. You can read the documentation for the details. The GitHub repository for my Mono image is at https://github.com/mikehadlow/ubuntu-monoxide-mono-devel. Notice how the Docker file is in the root of the repository. That’s the default location, but you can have multiple files in sub-directories if you want to support many images from a single repository. Now any time I push a change of my Dockerfile to GitHub, the docker build system will automatically build the image and update the docker index. You can see image listed here:https://index.docker.io/u/mikehadlow/ubuntu-monoxide-mono-devel/ I can now grab my image and run it interactively like this: $ sudo docker pull mikehadlow/ubuntu-monoxide-mono-devel Pulling repository mikehadlow/ubuntu-monoxide-mono-devel f259e029fcdd: Download complete 511136ea3c5a: Download complete 1c7f181e78b9: Download complete 9f676bd305a4: Download complete ce647670fde1: Download complete d6c54574173f: Download complete 6bcad8583de3: Download complete e82d34a742ff: Download complete $ sudo docker run -i mikehadlow/ubuntu-monoxide-mono-devel /bin/bash mono --version Mono JIT compiler version 3.2.8 (Debian 3.2.8+dfsg-1~pre1) Copyright (C) 2002-2014 Novell, Inc, Xamarin Inc and Contributors. www.mono-project.com TLS: __thread SIGSEGV: altstack Notifications: epoll Architecture: amd64 Disabled: none Misc: softdebug LLVM: supported, not enabled. GC: sgen exit Next let’s create a new local Dockerfile that compiles a simple ‘hello world’ program, and then runs it when we run the image. You can follow along with these steps. All you need is a Ubuntu machine with Docker installed. First here’s our ‘hello world’, save this code in a file named hello.cs: using System; namespace Mike.MonoTest { public class Program { public static void Main() { Console.WriteLine("Hello World"); } } } Next we’ll create our Dockerfile. Copy this code into a file called ‘Dockerfile’: #DOCKER-VERSION 0.9.1 FROM mikehadlow/ubuntu-monoxide-mono-devel ADD . /src RUN mcs /src/hello.cs CMD ["mono", "/src/hello.exe"] Once again, notice the ‘FROM’ line. This time we’re telling Docker to start with our mono image. The next line ‘ADD . /src’, tells Docker to copy the contents of the current directory (the one containing our Dockerfile) into a root directory named ‘src’ in the container. Now our hello.cs file is at /src/hello.cs in the container, so we can compile it with the mono C# compiler, mcs, which is the line ‘RUN mcs /src/hello.cs’. Now we will have the executable, hello.exe, in the src directory. The line ‘CMD [“mono”, “/src/hello.exe”]’ tells Docker what we want to happen when the container is run: just execute our hello.exe program. As an aside, this exercise highlights some questions around what best practice should be with Docker. We could have done this in several different ways. Should we build our software independently of the Docker build in some CI environment, or does it make sense to do it this way, with the Docker build as a step in our CI process? Do we want to rebuild our container for every commit to our software, or do we want the running container to pull the latest from our build output? Initially I’m quite attracted to the idea of building the image as part of the CI but I expect that we’ll have to wait a while for best practice to evolve. Anyway, for now let’s manually build our image: $ sudo docker build -t hello . Uploading context 1.684 MB Uploading context Step 0 : FROM mikehadlow/ubuntu-monoxide-mono-devel ---> f259e029fcdd Step 1 : ADD . /src ---> 6075dee41003 Step 2 : RUN mcs /src/hello.cs ---> Running in 60a3582ab6a3 ---> 0e102c1e4f26 Step 3 : CMD ["mono", "/src/hello.exe"] ---> Running in 3f75e540219a ---> 1150949428b2 Successfully built 1150949428b2 Removing intermediate container 88d2d28f12ab Removing intermediate container 60a3582ab6a3 Removing intermediate container 3f75e540219a You can see Docker executing each build step in turn and storing the intermediate result until the final image is created. Because we used the tag (-t) option and named our image ‘hello’, we can see it when we list all the docker images: $ sudo docker images REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE hello latest 1150949428b2 10 seconds ago 396.4 MB mikehadlow/ubuntu-monoxide-mono-devel latest f259e029fcdd 24 hours ago 394.7 MB ubuntu 13.10 9f676bd305a4 8 weeks ago 178 MB ubuntu saucy 9f676bd305a4 8 weeks ago 178 MB ... Now let’s run our image. The first time we do this Docker will create a container and run it. Each subsequent run will reuse that container: $ sudo docker run hello Hello World And that’s it. Imagine that instead of our little hello.exe, this image contained our web application, or maybe a service in some distributed software. In order to deploy it, we’d simply ask Docker to run it on any server we like; development, test, production, or on many servers in a web farm. This is an incredibly powerful way of doing consistent repeatable deployments. To reiterate, I think Docker is a game changer for large server side software. It’s one of the most exciting developments to have emerged this year and definitely worth your time to check out.

It’s a common pattern for command line tools to have multiple subcommands that run off of a single executable. For example, git fetch origin and git commit --amend both use the same executable /usr/bin/git to run. Each subcommand has its own set of required and optional parameters. This pattern is fairly easy to implement in your own Python command-line utilities using argparse. Here is a script that pretends to be git and provides the above two commands and arguments. #!/usr/bin/env python import argparse import sys class FakeGit(object): def __init__(self): parser = argparse.ArgumentParser( description='Pretends to be git', usage='''git [] The most commonly used git commands are: commit Record changes to the repository fetch Download objects and refs from another repository ''') parser.add_argument('command', help='Subcommand to run') # parse_args defaults to [1:] for args, but you need to # exclude the rest of the args too, or validation will fail args = parser.parse_args(sys.argv[1:2]) if not hasattr(self, args.command): print 'Unrecognized command' parser.print_help() exit(1) # use dispatch pattern to invoke method with same name getattr(self, args.command)() def commit(self): parser = argparse.ArgumentParser( description='Record changes to the repository') # prefixing the argument with -- means it's optional parser.add_argument('--amend', action='store_true') # now that we're inside a subcommand, ignore the first # TWO argvs, ie the command (git) and the subcommand (commit) args = parser.parse_args(sys.argv[2:]) print 'Running git commit, amend=%s' % args.amend def fetch(self): parser = argparse.ArgumentParser( description='Download objects and refs from another repository') # NOT prefixing the argument with -- means it's not optional parser.add_argument('repository') args = parser.parse_args(sys.argv[2:]) print 'Running git fetch, repository=%s' % args.repository if __name__ == '__main__': FakeGit() The argparse library gives you all kinds of great stuff. You can run ./git.py --help and get the following: usage: git [] The most commonly used git commands are: commit Record changes to the repository fetch Download objects and refs from another repository Pretends to be git positional arguments: command Subcommand to run optional arguments: -h, --help show this help message and exit You can get help on a particular subcommand with ./git.py commit --help. usage: git.py [-h] [--amend] Record changes to the repository optional arguments: -h, --help show this help message and exit --amend Want bash completion on your awesome new command line utlity? Try argcomplete, a drop in bash completion for Python + argparse.

I’ve just started looking at Docker. It’s a cool new technology that has the potential to make the management and deployment of distributed applications a great deal easier. I’d very much recommend checking it out. I’m especially interested in using it to deploy Mono applications because it promises to remove the hassle of deploying and maintaining the mono runtime on a multitude of Linux servers. I’ve been playing around creating new images and containers and debugging my Dockerfile, and I’ve wound up with lots of temporary containers and images. It’s really tedious repeatedly running ‘docker rm’ and ‘docker rmi’, so I’ve knocked up a couple of bash commands to bulk delete images and containers. Delete all containers: sudo docker ps -a -q | xargs -n 1 -I {} sudo docker rm {} Delete all un-tagged (or intermediate) images: sudo docker rmi $( sudo docker images | grep '' | tr -s ' ' | cut -d ' ' -f 3)

There is actually nothing very special about writing a Spring-boot web application purely using Scala, it just works! In this blog entry, I will slowly transform a Java based Spring-boot application completely to Scala - the Java based sample is available at this github location - https://github.com/bijukunjummen/spring-boot-mvc-test To start with, I had the option of going with either a maven based build or gradle based build - I opted to go with a gradle based build as gradle has a greatscala plugin, so for scala support the only changes to a build.gradle build script is the following: ... apply plugin: 'scala' ... jar { baseName = 'spring-boot-scala-web' version = '0.1.0' } dependencies { ... compile 'org.scala-lang:scala-library:2.10.2' ... } Essentially adding in the scala plugin and specifying the version of the scala-library. Now, I have one entity, a Hotel class, it transforms to the following with Scala: package mvctest.domain .... @Entity class Hotel { @Id @GeneratedValue @BeanProperty var id: Long = _ @BeanProperty var name: String = _ @BeanProperty var address: String = _ @BeanProperty var zip: String = _ } Every property is annotated with @BeanProperty annotation to instruct scala to generate the Java bean based getter and setter on the variables. With the entity in place a Spring-data repository for CRUD operations on this entity transforms from: import mvctest.domain.Hotel; import org.springframework.data.repository.CrudRepository; public interface HotelRepository extends CrudRepository { } to the following in Scala: import org.springframework.data.repository.CrudRepository import mvctest.domain.Hotel import java.lang.Long trait HotelRepository extends CrudRepository[Hotel, Long] And the Scala based controller which uses this repository to list the Hotels - vi... import org.springframework.web.bind.annotation.RequestMapping import org.springframework.stereotype.Controller import mvctest.service.HotelRepository import org.springframework.beans.factory.annotation.Autowired import org.springframework.ui.Model @Controller @RequestMapping(Array("/hotels")) class HotelController @Autowired() (private val hotelRepository: HotelRepository) { @RequestMapping(Array("/list")) def list(model: Model) = { val hotels = hotelRepository.findAll() model.addAttribute("hotels", hotels) "hotels/list" } } Here the constructor autowiring of the HotelRepository just works!. Do note the slightly awkward way of specifying the @Autowired annotation for constructor based injection. Finally, Spring-boot based application requires a main class to bootstrap the entire application, where this bootstrap class looks like this with Java: @Configuration @EnableAutoConfiguration @ComponentScan public class SampleWebApplication { public static void main(String[] args) { SpringApplication.run(SampleWebApplication.class, args); } } In scala, though I needed to provide two classes, one to specify the annotation and other to bootstrap the application, there may be better way to do this(blame it on my lack of Scala depth!) - package mvctest import org.springframework.context.annotation.Configuration import org.springframework.boot.autoconfigure.EnableAutoConfiguration import org.springframework.context.annotation.ComponentScan import org.springframework.boot.SpringApplication @Configuration @EnableAutoConfiguration @ComponentScan class SampleConfig object SampleWebApplication extends App { SpringApplication.run(classOf[SampleConfig]); } and that's it, with this set-up the entire application just works, the application can be started up with the following: ./gradlew build && java -jar build/libs/spring-boot-scala-web-0.1.0.jar and the sample endpoint listing the hotels accessed at this url: http://localhost:8080/hotels/list I have the entire git project available at this github location: https://github.com/bijukunjummen/spring-boot-scala-web In conclusion, Scala can be considered a first class citizen for a Spring-boot based application and there is no special configuration required to get a Scala based Spring-boot application to work. It just works!

So I finally made the decision on trying to learn Scala. Little did I know I was in for another round of IntelliJ integration hell. Let me rephrase that: IntelliJ with Gradle hell. I love Gradle. I love IntelliJ. However, the combination of the two is sometimes enough to drive me utterly crazy. Now take for example the Scala integration. I made the most simple Gradle build possible that compiles a standard Hello World application. apply plugin: 'scala' apply plugin: 'idea' repositories{ mavenCentral() mavenLocal() } dependencies{ compile 'org.slf4j:slf4j-api:1.7.5' compile "org.scala-lang:scala-library:2.10.4" compile "org.scala-lang:scala-compiler:2.10.4" testCompile "junit:junit:4.11" } task run(type: JavaExec, dependsOn: classes) { main = 'Main' classpath sourceSets.main.runtimeClasspath classpath configurations.runtime } First I stumbled upon the first issue: the Scala gradle plugin is incompatible with Java 8. Not a big issue, but this meant changing my java environment for this build, so it is a nuisance. Once this was fixed, the Gradle build succeeded and Hello World was printed out. I opened up IntelliJ and made sure the Scala plugin was installed. Then I imported the project using the Gradle build file. Everything looked okay, IntelliJ recognized the Scala source folder and provided the correct editor for the Scala source file. Then I tried to run the Main class. This resulted in a NoClassDefFoundException. IntelliJ didn’t want to compile my source classes. So I started digging. Apparently, the project was lacking a Scala facet. I’d expected IntelliJ to automatically add this once it saw I was using the scala plugin but it didn’t. So I tried manually adding the facet and there I got stuck. See, the facet requires you to state which scala compiler library you want to use. Luckily IntelliJ correctly added the jars to the classpath, so I was able to choose the correct jar. This, however, did not fix the issue as IntelliJ now complained it could not locate the scala runtime library (scala-library*.jar). This library was however included in the build. If you were to choose the runtime library as the scala library, it would complain it cannot find the compiler library. And this is where I am now: deadlocked. There is an issue in the bugtracker of IntelliJ here but it’s been eerily quiet at Jetbrains on this issue. As it is, it’s impossible to use IntelliJ with Gradle and Scala unless you’re willing to execute every bit of code including unit tests with Gradle instead of the IDE (which in effect defeats the purpose of an IDE). And I’ll die before adopting yet another build framework (SBT) that is supposed to work. Honestly, I really don’t know whether I want to learn Scala anymore. Just the fact that you can’t compile Scala in the most popular IDE at the moment when using the most popular build tool at the moment is something I cannot comprehend. Forcing me to adopt a Scala-specific build tool is unacceptable to me. If I were TypeSafe, I’d put an engineer on this and fix this as this would seriously aid in promoting the language. If it were easy to adopt Scala in an existing build cycle, it would pop up on more radars than it would right now. But it’s not just Scala and IntelliJ: most newer JVM languages struggle with IntelliJ. This is a real pity as this either forces me to change my IDE (i.e. Ceylon has its own IDE based on Eclipse) or not consider the language. As it is, the current viable option with IntelliJ is Java and Groovy (and Kotlin, but it’s not even near production ready quality). Wouldn’t it be nice to only need one IDE for all development? I couldn’t care less if it would cost $500, I just want things to work. I’d love to be able to write my AngularJS front-end that’s consuming my Scala/Java hydrid backend reading data from a MongoDB that’s feeded data from my Arduino sensors (for which I’ve written and uploaded the sketch from that same IDE).

Performance tuning SELECT statements can be a time consuming task which in my opinion follows Pareto principle’s. 20% effort is likely give you an 80% performance improvement. To get another 20% performance improvement you probably need to spend 80% of the time. Unless you work on the planet Venus where each day on Venus is equal to 243 Earth days, delivery deadlines are likely to mean you will not have enough time to put into tuning your SQL queries. After years writing and running SQL statements I began to develop a mental check-list of things I looked at when trying to improve query performance. These are the things I check before moving on to query plans and reading the sometimes complicated documentation of the database I am working on. My check-list is by no means comprehensive or scientific, more like a back of the envelope calculation but can I can say that most of the time I do get performance improvements following these simple steps. The check-list follows. Check Indexes There should be indexes on all fields used in the WHERE and JOIN portions of the SQL statement. Take the 3-Minute SQL performance test. Regardless of your score be sure to read through the answers as they are informative. Limit Size of Your Working Data Set Examine the tables used in the SELECT statement to see if you can apply filters in the WHERE clause of your statement. A classic example is when a query initially worked well when there were only a few thousand rows in the table. As the application grew the query slowed down. The solution may be as simple as restricting the query to looking at the current month’s data. When you have queries that have sub-selects, look to apply filtering to the inner statement of the sub-selects as opposed to the outer statements. Only Select Fields You Need Extra fields often increase the grain of the data returned and thus result in more (detailed) data being returned to the SQL client. Additionally: When using reporting and analytical applications, sometimes the slow report performance is because the reporting tool has to do the aggregation as data is received in detailed form. Occasionally the query may run quickly enough but your problem could be a network related issue as large amounts of detailed data are sent to the reporting server across the network. When using a column-oriented DBMS only the columns you have selected will be read from disk, the less columns you include in your query the less IO overhead. Remove Unnecessary Tables The reasons for removing unnecessary tables are the same as the reasons for removing fields not needed in the select statement. Writing SQL statements is a process that usually takes a number of iterations as you write and test your SQL statements. During development it is possible that you add tables to the query that may not have any impact on the data returned by the SQL code. Once the SQL is correct I find many people do not review their script and remove tables that do not have any impact or use in the final data returned. By removing the JOINS to these unnecessary tables you reduce the amount of processing the database has to do. Sometimes, much like removing columns you may find your reduce the data bring brought back by the database. Remove OUTER JOINS This can easier said than done and depends on how much influence you have in changing table content. One solution is to remove OUTER JOINS by placing placeholder rows in both tables. Say you have the following tables with an OUTER JOIN defined to ensure all data is returned: customer_id customer_name 1 John Doe 2 Mary Jane 3 Peter Pan 4 Joe Soap customer_id sales_person NULL Newbee Smith 2 Oldie Jones 1 Another Oldie NULL Greenhorn The solution is to add a placeholder row in the customer table and update all NULL values in the sales table to the placeholder key. customer_id customer_name 0 NO CUSTOMER 1 John Doe 2 Mary Jane 3 Peter Pan 4 Joe Soap customer_id sales_person 0 Newbee Smith 2 Oldie Jones 1 Another Oldie 0 Greenhorn Not only have you removed the need for an OUTER JOIN you have also standardised how sales people with no customers are represented. Other developers will not have to write statements such as ISNULL(customer_id, “No customer yet”). Remove Calculated Fields in JOIN and WHERE Clauses This is another one of those that may at times be easier said than done depending on your permissions to make changes to the schema. This can be done by creating a field with the calculated values used in the join on the table. Given the following SQL statement: FROM sales a JOIN budget b ON ((year(a.sale_date)* 100) + month(a.sale_date)) = b.budget_year_month Performance can be improved by adding a column with the year and month in the sales table. The updated SQL statement would be as follows: SELECT * FROM PRODUCTSFROM sales a JOIN budget b ON a.sale_year_month = b.budget_year_month Conclusion The recommendations boil down to a few short pointers check for indexes work with the smallest data set required remove unnecessary fields and tables and remove calculations in your JOIN and WHERE clauses. If all these recommendations fail to improve your SQL query performance my last suggestion is you move to Venus. All you will need is a single day to tune your SQL.

want to add java 8 support to kepler? java 8 has not yet landed in our standard download packages . but you can add it to your existing eclipse kepler package. i’ve got three different eclipse installations running java 8: a brand new kepler sr2 installation of the eclipse ide for java developers; a slightly used kepler sr1 installation of the eclipse for rcp/rap developers (with lots of other features already added); and a nightly build (dated march 24/2014) of eclipse 4.4 sdk. the jdt team recommends that you start from kepler sr2, the second and final service release for kepler (but using the exact same steps, i’ve installed it into kepler sr1 and sr2 packages). there are some detailed instructions for adding java 8 support by installing a feature patch in the eclipsepedia wiki . the short version is this: from kepler sr2, use the “help > install new software…” menu option to open the “available software” dialog; enter http://download.eclipse.org/eclipse/updates/4.3-p-builds/ into the “work with” field (highlighted below); put a checkbox next to “eclipse java 8 support (for kepler sr2)” (highlighted below); click “next”, click “next”, read and accept the license, and click “finish” watch the pretty progress bar move relatively quickly across the bottom of the window; and restart eclipse when prompted. select “help > install new software…” to open the available software dialog. voila! support for java 8 is installed. if you’ve already got the java 8 jdk installed and the corresponding jre is the default on your system, you’re done. if you’re not quite ready to make the leap to a java 8 jre, there’s still hope (my system is still configured with java 7 as the default). install the java 8 jdk; open the eclipse preferences, and navigate to “java > installed jres”; java runtime environment preferences click “add…”; select “standard vm”, click “next”; enter the path to the java 8 jre (note that this varies depending on platform, and how you obtain and install the bits); java 8 jre definition click “finish”. before closing the preferences window, you can set your workspace preference to use the newly-installed java 8 jre. or, if you’re just planning to experiment with java 8 for a while, you can configure this on a project-by-project basis. in the create a java project dialog, specify that your project will use a javase-1.8 jre. it’s probably better to do this on the project as this will become a project setting that will follow the project into your version control system. next step… learn how wrong my initial impressions of java 8 were (hint: it’s far better). the lambda is so choice. if you have the means, i highly recommend picking one up. about these ads

Spring WebApplicationInitializer provides a programatic way to configure the Spring DispatcherServlet and ContextLoaderListener in Servlet 3.0+ compliant servlet containers , rather than adding this configuration through a web.xml file. This is a quick note to show how implementation through WebApplicationInitializer interface internally works, given that this interface does not derive from any Servlet related interface! The answer is the ServletContainerInitializer interface introduced with Servlet 3.0 specification, implementors of this interface are notified during the context startup phase and can perform any programatic registration through the provided ServletContext. Spring implements the ServletContainerInitializer through SpringServletContainerInitializer class. Per the Servlet specs, this implementation must be declared in a META-INF/services/javax.servlet.ServletContainerInitializer file of the libraries jar file - Spring declares this in spring-web*.jar jar file and has an entry `org.springframework.web.SpringServletContainerInitializer` SpringServletContainerInitializer class has a @HandlerTypes annotation with a value of WebApplicationInitializer, this means that the Servlet container will scan for classes implementing the WebApplicationInitializer implementation and call the onStartUp method with these classes and that is where the WebApplicationInitializer fits in. A little convoluted, but the good thing is all these details are totally abstracted away within the spring-web framework and the developer only has to configure an implementation of WebApplicationInitializer and live in a web.xml free world.

Recently, I had to take some content in markdown, specifically markdown extra, and convert it to a series of PDFs styled with a specific branding. While some will argue that PDFs are dead and “long live the web”, many of us still need to produce PDFs for one reason or another. In this case I had to take markdown extra, with some html sprinkled in, clean it up, and convert it to a styled PDF. What follows is how I did that using QueryPath for the cleanup and DOMPDF to make the conversion. The Setup At the root of this little app was a PHP script with the dependencies managed through composer. The composer.json file looked like: { "name": "foo/bar", "description": "Convert markdown to PDF.", "type": "application", "require": { "php": ">=5.3.0", "michelf/php-markdown": "1.4.*", "dompdf/dompdf" : "0.6.*", "querypath/querypath": "3.*", "masterminds/html5": "1.*" } } Turning the Markdown into HTML Within the script I started with a file we’ll call $file. Form here it was easy using the official markdown extra conversion utility. $markdown = file_get_contents($file); $markdownParser = new \Michelf\MarkdownExtra(); $html = $markdownParser->transform($markdown); This produces the html needed to go inside the body of an html page. From here I wrapped it in a document because I could easily link to a CSS file for styling purposes. DOMPDF supports quite a bit of CSS 2.1. $html = '' . $html . '’; pdf.css is where you can style the PDF. If you know how to style web pages using CSS you can manage to style a PDF document. Cleaning Up The Content There were a number of places html had been injected into the markdown that was either broken, unwanted in a PDF, or an edge case that DOMPDF didn’t support. To make these changes I used QueryPath. For example, I needed to take relative links, normally used in generation of a website, and add a domain name to them: $dom = \HTML5::loadHTML($html); $links = htmlqp($dom, 'a'); foreach ($links as $link) { $href = $link->attr('href'); if (substr($href, 0, 1) == '/' && substr($href, 1, 1) != '/') { $link->attr('href', $domain_name . $href); } } $html = \HTML5::saveHTML($dom); Note, I used the HTML5 parser and writer rather than the built-in one designed for xhtml and HTML 4. This is because DOMPDF attempts to work with HTML5 and I wanted to keep that consistent from the beginning. Converting to PDF There is a little setup before using DOMPDF. It has a built in autoloader which should be disabled and needs a config file. In my case I used the default config file and handled this with: define('DOMPDF_ENABLE_AUTOLOAD', false); require_once __DIR__ . '/vendor/dompdf/dompdf/dompdf_config.inc.php'; The conversion was fairly straight forward. I used a snippet like: $dompdf = new DOMPDF(); $dompdf->load_html($html); $dompdf->render(); $output = $dompdf->output(); file_put_contents(‘path/to/file.pdf', $output); DOMPDF has a lot of options and some quirks. It wasn’t exactly designed for composer. For example, if you want to work with custom fonts you need to get the project from git and install submodules. Despite the quirks, needing to cleanup some of the html, and brand the documents, I was able to write a conversion script that handled dozens of documents quickly. Almost all of my time was on html cleanup and css styling.

In SQL Server management studio, using, View, Registered Servers (Ctrl+Alt+G) set up the servers that you want to execute the same query across all servers for, right click the group, select new query. Then when you execute the query, the results will come back with the first column showing you the database instance that that row came from.

over the last several months, i've been developing a rest api using spring boot . my client hired an outside company to develop a native ios app, and my development team was responsible for developing its api. our main task involved integrating with epic , a popular software system used in health care. we also developed a crowd -backed authentication system, based loosely on philip sorst's angular rest security . to document our api, we used spring mvc integration for swagger (a.k.a. swagger-springmvc). i briefly looked into swagger4spring-web , but gave up quickly when it didn't recognize spring's @restcontroller. we started with swagger-springmvc 0.6.5 and found it fairly easy to integrate. unfortunately, it didn't allow us to annotate our model objects and tell clients which fields were required. we were quite pleased when a new version (0.8.2) was released that supports swagger 1.3 and its @apimodelproperty. what is swagger? the goal of swagger is to define a standard, language-agnostic interface to rest apis which allows both humans and computers to discover and understand the capabilities of the service without access to source code, documentation, or through network traffic inspection. to demonstrate how swagger works, i integrated it into josh long's x-auth-security project. if you have a boot-powered project, you should be able to use the same steps. 1. add swagger-springmvc dependency to your project. com.mangofactory swagger-springmvc 0.8.2 note: on my client's project, we had to exclude "org.slf4j:slf4j-log4j12" and add "jackson-module-scala_2.10:2.3.1" as a dependency. i did not need to do either of these in this project. 2. add a swaggerconfig class to configure swagger. the swagger-springmvc documentation has an example of this with a bit more xml. package example.config; import com.mangofactory.swagger.configuration.jacksonscalasupport; import com.mangofactory.swagger.configuration.springswaggerconfig; import com.mangofactory.swagger.configuration.springswaggermodelconfig; import com.mangofactory.swagger.configuration.swaggerglobalsettings; import com.mangofactory.swagger.core.defaultswaggerpathprovider; import com.mangofactory.swagger.core.swaggerapiresourcelisting; import com.mangofactory.swagger.core.swaggerpathprovider; import com.mangofactory.swagger.scanners.apilistingreferencescanner; import com.wordnik.swagger.model.*; import org.springframework.beans.factory.annotation.autowired; import org.springframework.beans.factory.annotation.value; import org.springframework.context.annotation.bean; import org.springframework.context.annotation.componentscan; import org.springframework.context.annotation.configuration; import java.util.arraylist; import java.util.arrays; import java.util.list; import static com.google.common.collect.lists.newarraylist; @configuration @componentscan(basepackages = "com.mangofactory.swagger") public class swaggerconfig { public static final list default_include_patterns = arrays.aslist("/news/.*"); public static final string swagger_group = "mobile-api"; @value("${app.docs}") private string docslocation; @autowired private springswaggerconfig springswaggerconfig; @autowired private springswaggermodelconfig springswaggermodelconfig; /** * adds the jackson scala module to the mappingjackson2httpmessageconverter registered with spring * swagger core models are scala so we need to be able to convert to json * also registers some custom serializers needed to transform swagger models to swagger-ui required json format */ @bean public jacksonscalasupport jacksonscalasupport() { jacksonscalasupport jacksonscalasupport = new jacksonscalasupport(); //set to false to disable jacksonscalasupport.setregisterscalamodule(true); return jacksonscalasupport; } /** * global swagger settings */ @bean public swaggerglobalsettings swaggerglobalsettings() { swaggerglobalsettings swaggerglobalsettings = new swaggerglobalsettings(); swaggerglobalsettings.setglobalresponsemessages(springswaggerconfig.defaultresponsemessages()); swaggerglobalsettings.setignorableparametertypes(springswaggerconfig.defaultignorableparametertypes()); swaggerglobalsettings.setparameterdatatypes(springswaggermodelconfig.defaultparameterdatatypes()); return swaggerglobalsettings; } /** * api info as it appears on the swagger-ui page */ private apiinfo apiinfo() { apiinfo apiinfo = new apiinfo( "news api", "mobile applications and beyond!", "https://helloreverb.com/terms/", "[email protected]", "apache 2.0", "http://www.apache.org/licenses/license-2.0.html" ); return apiinfo; } /** * configure a swaggerapiresourcelisting for each swagger instance within your app. e.g. 1. private 2. external apis * required to be a spring bean as spring will call the postconstruct method to bootstrap swagger scanning. * * @return */ @bean public swaggerapiresourcelisting swaggerapiresourcelisting() { //the group name is important and should match the group set on apilistingreferencescanner //note that swaggercache() is by defaultswaggercontroller to serve the swagger json swaggerapiresourcelisting swaggerapiresourcelisting = new swaggerapiresourcelisting(springswaggerconfig.swaggercache(), swagger_group); //set the required swagger settings swaggerapiresourcelisting.setswaggerglobalsettings(swaggerglobalsettings()); //use a custom path provider or springswaggerconfig.defaultswaggerpathprovider() swaggerapiresourcelisting.setswaggerpathprovider(apipathprovider()); //supply the api info as it should appear on swagger-ui web page swaggerapiresourcelisting.setapiinfo(apiinfo()); //global authorization - see the swagger documentation swaggerapiresourcelisting.setauthorizationtypes(authorizationtypes()); //every swaggerapiresourcelisting needs an apilistingreferencescanner to scan the spring request mappings swaggerapiresourcelisting.setapilistingreferencescanner(apilistingreferencescanner()); return swaggerapiresourcelisting; } @bean /** * the apilistingreferencescanner does most of the work. * scans the appropriate spring requestmappinghandlermappings * applies the correct absolute paths to the generated swagger resources */ public apilistingreferencescanner apilistingreferencescanner() { apilistingreferencescanner apilistingreferencescanner = new apilistingreferencescanner(); //picks up all of the registered spring requestmappinghandlermappings for scanning apilistingreferencescanner.setrequestmappinghandlermapping(springswaggerconfig.swaggerrequestmappinghandlermappings()); //excludes any controllers with the supplied annotations apilistingreferencescanner.setexcludeannotations(springswaggerconfig.defaultexcludeannotations()); // apilistingreferencescanner.setresourcegroupingstrategy(springswaggerconfig.defaultresourcegroupingstrategy()); //path provider used to generate the appropriate uri's apilistingreferencescanner.setswaggerpathprovider(apipathprovider()); //must match the swagger group set on the swaggerapiresourcelisting apilistingreferencescanner.setswaggergroup(swagger_group); //only include paths that match the supplied regular expressions apilistingreferencescanner.setincludepatterns(default_include_patterns); return apilistingreferencescanner; } /** * example of a custom path provider */ @bean public apipathprovider apipathprovider() { apipathprovider apipathprovider = new apipathprovider(docslocation); apipathprovider.setdefaultswaggerpathprovider(springswaggerconfig.defaultswaggerpathprovider()); return apipathprovider; } private list authorizationtypes() { arraylist authorizationtypes = new arraylist<>(); list authorizationscopelist = newarraylist(); authorizationscopelist.add(new authorizationscope("global", "access all")); list granttypes = newarraylist(); loginendpoint loginendpoint = new loginendpoint(apipathprovider().getappbasepath() + "/user/authenticate"); granttypes.add(new implicitgrant(loginendpoint, "access_token")); return authorizationtypes; } @bean public swaggerpathprovider relativeswaggerpathprovider() { return new apirelativeswaggerpathprovider(); } private class apirelativeswaggerpathprovider extends defaultswaggerpathprovider { @override public string getappbasepath() { return "/"; } @override public string getswaggerdocumentationbasepath() { return "/api-docs"; } } } the apipathprovider class referenced above is as follows: package example.config; import com.mangofactory.swagger.core.swaggerpathprovider; import org.springframework.beans.factory.annotation.autowired; import org.springframework.web.util.uricomponentsbuilder; import javax.servlet.servletcontext; public class apipathprovider implements swaggerpathprovider { private swaggerpathprovider defaultswaggerpathprovider; @autowired private servletcontext servletcontext; private string docslocation; public apipathprovider(string docslocation) { this.docslocation = docslocation; } @override public string getapiresourceprefix() { return defaultswaggerpathprovider.getapiresourceprefix(); } public string getappbasepath() { return uricomponentsbuilder .fromhttpurl(docslocation) .path(servletcontext.getcontextpath()) .build() .tostring(); } @override public string getswaggerdocumentationbasepath() { return uricomponentsbuilder .fromhttpurl(getappbasepath()) .pathsegment("api-docs/") .build() .tostring(); } @override public string getrequestmappingendpoint(string requestmappingpattern) { return defaultswaggerpathprovider.getrequestmappingendpoint(requestmappingpattern); } public void setdefaultswaggerpathprovider(swaggerpathprovider defaultswaggerpathprovider) { this.defaultswaggerpathprovider = defaultswaggerpathprovider; } } in src/main/resources/application.properties , add an "app.docs" property. this will need to be changed as you move your application from local -> test -> staging -> production. spring boot's externalized configuration makes this fairly simple. app.docs=http://localhost:8080 3. verify swagger produces json. after completing the above steps, you should be able to see the json swagger generates for your api. open http://localhost:8080/api-docs in your browser or curl http://localhost:8080/api-docs . { "apiversion": "1", "swaggerversion": "1.2", "apis": [ { "path": "http://localhost:8080/api-docs/mobile-api/example_newscontroller", "description": "example.newscontroller" } ], "info": { "title": "news api", "description": "mobile applications and beyond!", "termsofserviceurl": "https://helloreverb.com/terms/", "contact": "[email protected]", "license": "apache 2.0", "licenseurl": "http://www.apache.org/licenses/license-2.0.html" } } 4. copy swagger ui into your project. swagger ui is a good-looking javascript client for swagger's json. i integrated it using the following steps: git clone https://github.com/wordnik/swagger-ui cp -r swagger-ui/dist ~/dev/x-auth-security/src/main/resources/public/docs i modified docs/index.html, deleting its header () element, as well as made its url dynamic. ... $(function () { var apiurl = window.location.protocol + "//" + window.location.host; if (window.location.pathname.indexof('/api') > 0) { apiurl += window.location.pathname.substring(0, window.location.pathname.indexof('/api')) } apiurl += "/api-docs"; log('api url: ' + apiurl); window.swaggerui = new swaggerui({ url: apiurl, dom_id: "swagger-ui-container", ... after making these changes, i was able to open fire up the app with "mvn spring-boot:run" and view http://localhost:8080/docs/index.html in my browser. 5. annotate your api. there are two services in x-auth-security: one for authentication and one for news. to provide more information to the "news" service's documentation, add @api and @apioperation annotations. these annotations aren't necessary to get a service to show up in swagger ui, but if you don't specify the @api("user"), you'll end up with an ugly-looking class name instead (e.g. example_xauth_userxauthtokencontroller). @restcontroller @api(value = "news", description = "news api") class newscontroller { map entries = new concurrenthashmap(); @requestmapping(value = "/news", method = requestmethod.get) @apioperation(value = "get news", notes = "returns news items") collection entries() { return this.entries.values(); } @requestmapping(value = "/news/{id}", method = requestmethod.delete) @apioperation(value = "delete news item", notes = "deletes news item by id") newsentry remove(@pathvariable long id) { return this.entries.remove(id); } @requestmapping(value = "/news/{id}", method = requestmethod.get) @apioperation(value = "get a news item", notes = "returns a news item") newsentry entry(@pathvariable long id) { return this.entries.get(id); } @requestmapping(value = "/news/{id}", method = requestmethod.post) @apioperation(value = "update news", notes = "updates a news item") newsentry update(@requestbody newsentry news) { this.entries.put(news.getid(), news); return news; } ... } you might notice the screenshot above only shows news. this is because swaggerconfig.default_include_patterns only specifies news. the following will include all apis. public static final list default_include_patterns = arrays.aslist("/.*"); after adding these annotations and modifying swaggerconfig , you should see all available services. in swagger-springmvc 0.8.x, the ability to use @apimodel and @apimodelproperty annotations was added. this means you can annotate newsentry to specify which fields are required. @apimodel("news entry") public static class newsentry { @apimodelproperty(value = "the id of the item", required = true) private long id; @apimodelproperty(value = "content", required = true) private string content; // getters and setters } this results in the model's documentation showing up in swagger ui. if "required" isn't specified, a property shows up as optional . parting thoughts the qa engineers and 3rd party ios developers have been very pleased with our api documentation. i believe this is largely due to swagger and its nice-looking ui. the swagger ui also provides an interface to test the endpoints by entering parameters (or json) into html forms and clicking buttons. this could benefit those qa folks that prefer using selenium to test html (vs. raw rest endpoints). i've been quite pleased with swagger-springmvc, so kudos to its developers. they've been very responsive in fixing issues i've reported . the only thing i'd like is support for recognizing jsr303 annotations (e.g. @notnull) as required fields. to see everything running locally, checkout my modified x-auth-security project on github and the associated commits for this article.

Here's a great JDK 8 command-line static dependency checker.

A Mule application which uses the Jboss TX transaction manager needs a persistent Object Store to hold the objects and states of the transactions being processed (further information about different object stores can be found in the following page). By default Mule uses the ShadowNoFileLockStorem, which uses the file system to store the objects. As one can guess, if an application does not have permission to write the object store to the file system, the Jboss Transaction Manager will not be able to work properly and will throw an exception similar to the following: com.arjuna.ats.arjuna: ARJUNA12218: cant create new instance of {0} java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ... Caused by: com.arjuna.ats.arjuna.exceptions.ObjectStoreException: ARJUNA12225: FileSystemStore::setupStore - cannot access root of object store: //ObjectStore/ShadowNoFileLockStore/defaultStore/ at com.arjuna.ats.internal.arjuna.objectstore.FileSystemStore.(FileSystemStore.java:482) at com.arjuna.ats.internal.arjuna.objectstore.ShadowingStore.(ShadowingStore.java:619) at com.arjuna.ats.internal.arjuna.objectstore.ShadowNoFileLockStore.(ShadowNoFileLockStore.java:53) ... 36 more Since the object store is not created, the XA Transaction Manager is not initialised properly. This will throw a ‘Could not initialize class’ exception whenever the transaction manager is invoked. org.mule.exception.DefaultSystemExceptionStrategy: Caught exception in Exception Strategy: errorCode: 0 javax.resource.spi.work.WorkCompletedException: errorCode: 0 at org.mule.work.WorkerContext.run(WorkerContext.java:335) at java.util.concurrent.ThreadPoolExecutor$CallerRunsPolicy.rejectedExecution(ThreadPoolExecutor.java:2025) ... Caused by: java.lang.NoClassDefFoundError: Could not initialize class com.arjuna.ats.arjuna.coordinator.TxControl at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.begin(BaseTransaction.java:87) at org.mule.transaction.XaTransaction.doBegin(XaTransaction.java:63) at org.mule.transaction.AbstractTransaction.begin(AbstractTransaction.java:66) at org.mule.transaction.XaTransactionFactory.beginTransaction(XaTransactionFactory.java:32) at org.mule.execution.BeginAndResolveTransactionInterceptor.execute(BeginAndResolveTransactionInterceptor.java:51) at org.mule.execution.ResolvePreviousTransactionInterceptor.execute(ResolvePreviousTransactionInterceptor.java:48) at org.mule.execution.SuspendXaTransactionInterceptor.execute(SuspendXaTransactionInterceptor.java:54) at org.mule.execution.ValidateTransactionalStateInterceptor.execute(ValidateTransactionalStateInterceptor.java:44) at org.mule.execution.IsolateCurrentTransactionInterceptor.execute(IsolateCurrentTransactionInterceptor.java:44) at org.mule.execution.ExternalTransactionInterceptor.execute(ExternalTransactionInterceptor.java:52) at org.mule.execution.RethrowExceptionInterceptor.execute(RethrowExceptionInterceptor.java:32) at org.mule.execution.RethrowExceptionInterceptor.execute(RethrowExceptionInterceptor.java:17) at org.mule.execution.TransactionalErrorHandlingExecutionTemplate.execute(TransactionalErrorHandlingExecutionTemplate.java:113) at org.mule.execution.TransactionalErrorHandlingExecutionTemplate.execute(TransactionalErrorHandlingExecutionTemplate.java:34) at org.mule.transport.jms.XaTransactedJmsMessageReceiver.poll(XaTransactedJmsMessageReceiver.java:214) at org.mule.transport.AbstractPollingMessageReceiver.performPoll(AbstractPollingMessageReceiver.java:219) at org.mule.transport.PollingReceiverWorker.poll(PollingReceiverWorker.java:84) at org.mule.transport.PollingReceiverWorker.run(PollingReceiverWorker.java:53) at org.mule.work.WorkerContext.run(WorkerContext.java:311) ... 15 more Mule computes the default directory where to write the object store as follows : muleInternalDir = config.getWorkingDirectory(); (see the code for further analysis). If Mule is started from a directory where the user does not have write permissions, the problems mentioned above will be faced. The easiest way to fix this issue is to make sure that the user running Mule as full write permission to the working directory. If that cannot be achieved, fear not, there is a solution. On first analysis, one would be tempted to set the Object Store Directory by using Spring properties as follows: Unfortunately this will not work since the Jboss Transaction Manager is a Singleton and this property is used in the constructor of the object. Hence a behaviour similar to the following will be experienced: Caused by: com.arjuna.ats.arjuna.exceptions.ObjectStoreException: ARJUNA12225: FileSystemStore::setupStore - cannot access root of object store: PutObjectStoreDirHere/ShadowNoFileLockStore/defaultStore/ (Please note that “PutObjectStoreDirHere” is the default directory assigned by the JBoss TX transaction manager). One way to go around this issue is to be sure that these properties are set before the object is initialised. There are at least two ways to be sure that this is achieved: 1. Set the properties on start up as follows: ./mule -M-Dcom.arjuna.ats.arjuna.objectstore.objectStoreDir=/path/to/objectstoreDir -M-DObjectStoreEnvironmentBean.objectStoreDir=/path/to/objectstoreDir 2. Set the properties in the wrapper.config as follow: wrapper.java.additional.x=-Dcom.arjuna.ats.arjuna.objectstore.objectStoreDir=/path/to/objectstoreDir wrapper.java.additional.x=-DObjectStoreEnvironmentBean.objectStoreDir=/path/to/objectstoreDir (x is the next number available in the wrapper.config by default this is 4). Otherwise, take the easiest route and make sure that Mule can write to the start up directory.

Every GitHub repository comes with its own wiki. This is a great place to put the documentation for your project. What isn’t clear from the wiki documentation is how to add images to your wiki. Here’s my step-by-step guide. I’m going to add a logo to the main page of my WikiDemo repository’s wiki: https://github.com/mikehadlow/WikiDemo/wiki/Main-Page First clone the wiki. You grab the clone URL from the button at the top of the wiki page. $ git clone [email protected]:mikehadlow/WikiDemo.wiki.git Cloning into 'WikiDemo.wiki'... Enter passphrase for key '/home/mike.hadlow/.ssh/id_rsa': remote: Counting objects: 6, done. remote: Compressing objects: 100% (3/3), done. remote: Total 6 (delta 0), reused 0 (delta 0) Receiving objects: 100% (6/6), done. Create a new directory called ‘images’ (it doesn’t matter what you call it, this is just a convention I use): $ mkdir images Then copy your picture(s) into the images directory (I’ve copied my logo_design.png file to my images directory). $ ls -l -rwxr-xr-x 1 mike.hadlow Domain Users 12971 Sep 5 2013 logo_design.png Commit your changes and push back to GitHub: $ git add -A $ git status # On branch master # Changes to be committed: # (use "git reset HEAD ..." to unstage) # # new file: images/logo_design.png # $ git commit -m "Added logo_design.png" [master 23a1b4a] Added logo_design.png 1 files changed, 0 insertions(+), 0 deletions(-) create mode 100755 images/logo_design.png $ git push Enter passphrase for key '/home/mike.hadlow/.ssh/id_rsa': Counting objects: 5, done. Delta compression using up to 4 threads. Compressing objects: 100% (3/3), done. Writing objects: 100% (4/4), 9.05 KiB, done. Total 4 (delta 0), reused 0 (delta 0) To [email protected]:mikehadlow/WikiDemo.wiki.git 333a516..23a1b4a master -> master Now we can put a link to our image in ‘Main Page’: Save and there’s your image for all to see:

We all know we need to use connection pools where ever we connect to a database. All of the modern drivers using JDBC type 4 support it. In this post we will have look at an overview ofconnection pooling in spring applications and how to deal with same context in a non JEE enviorements (like tests). Most examples of connecting to database in spring is done using DriverManagerDataSource. If you don't read the documentation properly then you are going to miss a very important point. NOTE: This class is not an actual connection pool; it does not actually pool Connections. It just serves as simple replacement for a full-blown connection pool, implementing the same standard interface, but creating new Connections on every call. Useful for test or standalone environments outside of a J2EE container, either as a DataSource bean in a corresponding ApplicationContext or in conjunction with a simple JNDI environment. Pool-assuming Connection.close() calls will simply close the Connection, so any DataSource-aware persistence code should work. Yes, by default the spring applications does not use pooled connections. There are two ways to implement the connection pooling. Depending on who is managing the pool. If you are running in a JEE environment, then it is prefered use the container for it. In a non-JEE setup there are libraries which will help the application to manage the connection pools. Lets discuss them in bit detail below. 1. Server (Container) managed connection pool (Using JNDI) When the application connects to the database server, establishing the physical actual connection takes much more than the execution of the scripts. Connection pooling is a technique that was pioneered by database vendors to allow multiple clients to share a cached set of connection objects that provide access to a database resource. The JavaWorld article gives a good overview about this. In a J2EE container, it is recommended to use a JNDI DataSource provided by the container. Such a DataSource can be exposed as a DataSource bean in a Spring ApplicationContext via JndiObjectFactoryBean, for seamless switching to and from a local DataSource bean like this class. The below articles helped me in setting up the data source in JBoss AS. 1. DebaJava Post 2. JBoss Installation Guide 3. JBoss Wiki Next step is to use these connections created by the server from the application. As mentioned in the documentation you can use the JndiObjectFactoryBean for this. It is as simple as below If you want to write any tests using springs "SpringJUnit4ClassRunner" it can't load the context becuase the JNDI resource will not be available. For tests, you can then either set up a mock JNDI environment through Spring's SimpleNamingContextBuilder, or switch the bean definition to a local DataSource (which is simpler and thus recommended). As I was looking for a good solutions to this problem (I did not want a separate context for tests) this SO answer helped me. It sort of uses the various tips given in the Javadoc to good effect. The issue with the above solution is the repetition of code to create the JNDI connections. I have solved it using a customized runner SpringWithJNDIRunner. This class adds the JNDI capabilities to the SpringJUnit4ClassRunner. It reads the data source from "test-datasource.xml" file in the class path and binds it to the JNDI resource with name "java:/my-ds". After the execution of this code the JNDI resource is available for the spring container to consume. import javax.naming.NamingException; import org.junit.runners.model.InitializationError; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.mock.jndi.SimpleNamingContextBuilder; import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; /** * This class adds the JNDI capabilities to the SpringJUnit4ClassRunner. * @author mkadicha * */ public class SpringWithJNDIRunner extends SpringJUnit4ClassRunner { public static boolean isJNDIactive; /** * JNDI is activated with this constructor. * * @param klass * @throws InitializationError * @throws NamingException * @throws IllegalStateException */ public SpringWithJNDIRunner(Class klass) throws InitializationError, IllegalStateException, NamingException { super(klass); synchronized (SpringWithJNDIRunner.class) { if (!isJNDIactive) { ApplicationContext applicationContext = new ClassPathXmlApplicationContext( "test-datasource.xml"); SimpleNamingContextBuilder builder = new SimpleNamingContextBuilder(); builder.bind("java:/my-ds", applicationContext.getBean("dataSource")); builder.activate(); isJNDIactive = true; } } } } To use this runner you just need to use the annotation @RunWith(SpringWithJNDIRunner.class) in your test. This class extends SpringJUnit4ClassRunner beacuse a there can only be one class in the @RunWith annotation. The JNDI is created only once is a test cycle. This class provides a clean solution to the problem. 2. Application managed connection pool If you need a "real" connection pool outside of a J2EE container, consider Apache's Jakarta Commons DBCP or C3P0. Commons DBCP's BasicDataSource and C3P0's ComboPooledDataSource are full connection pool beans, supporting the same basic properties as this class plus specific settings (such as minimal/maximal pool size etc). Below user guides can help you configure this. 1. Spring Docs 2. C3P0 Userguide 3. DBCP Userguide The below articles speaks about the general guidelines and best practices in configuring the connection pools. 1. SO question on Spring JDBC Connection pools 2. Connection pool max size in MS SQL Server 2008 3. How to decide the max number of connections 4. Monitoring the number of active connections in SQL Server 2008 Note:- All the text in italics are copied from the spring documentation of the DriverManagerDataSource.