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  • Spring Custom Filter Problem?

    - by mr.lost
    greetings all,iam using spring security 3 and i want to perform some logic(saving some data in the session) when the user is visiting the site and he's remembered so i extended the GenericFilterBean class and performed the logic in the doFilter method then complete the filter chain by calling the chain.doFilter method,and then inserted that filter after the remember me filter in the security.xml file? but there's a problem is the filter is executed on each page even if the user is remembered or not is there's something wrong with the filter implementation or the position of the filter? and i have a simple question,is the filter chain by default is executed on each page? and when making a custom filter should i add it to the web.xml too? the filter class: package projects.internal; import java.io.IOException; import javax.servlet.FilterChain; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.security.core.Authentication; import org.springframework.security.core.context.SecurityContextHolder; import org.springframework.web.filter.GenericFilterBean; import projects.ProjectManager; public class rememberMeFilter extends GenericFilterBean { private ProjectManager projectManager; @Autowired public rememberMeFilter(ProjectManager projectManager) { this.projectManager = projectManager; } @Override public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { System.out.println("In The Filter"); Authentication auth = (Authentication) SecurityContextHolder .getContext().getAuthentication(); HttpServletResponse response = ((HttpServletResponse) res); HttpServletRequest request = ((HttpServletRequest) req); // if the user is not remembered,do nothing if (auth == null) { chain.doFilter(request, response); } else { // the user is remembered save some data in the session System.out.println("User Is Remembered"); chain.doFilter(request, response); } } } the security.xml file: <beans:beans xmlns="http://www.springframework.org/schema/security" xmlns:beans="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/security http://www.springframework.org/schema/security/spring-security-3.0.xsd"> <global-method-security pre-post-annotations="enabled"> </global-method-security> <http use-expressions="true" > <remember-me data-source-ref="dataSource"/> <intercept-url pattern="/" access="permitAll" /> <intercept-url pattern="/images/**" filters="none" /> <intercept-url pattern="/scripts/**" filters="none" /> <intercept-url pattern="/styles/**" filters="none" /> <intercept-url pattern="/p/login" filters="none" /> <intercept-url pattern="/p/register" filters="none" /> <intercept-url pattern="/p/forgot_password" filters="none" /> <intercept-url pattern="/p/**" access="isAuthenticated()" /> <custom-filter after="REMEMBER_ME_FILTER" ref="rememberMeFilter" /> <form-login login-processing-url="/j_spring_security_check" login-page="/p/login" authentication-failure-url="/p/login?login_error=1" default-target-url="/p/dashboard" authentication-success-handler-ref="myAuthenticationHandler" always-use-default-target="false" /> <logout/> </http> <beans:bean id="myAuthenticationHandler" class="projects.internal.myAuthenticationHandler" /> <beans:bean id="rememberMeFilter" class="projects.internal.rememberMeFilter" > </beans:bean> <authentication-manager alias="authenticationManager"> <authentication-provider> <password-encoder hash="md5" /> <jdbc-user-service data-source-ref="dataSource" /> </authentication-provider> </authentication-manager> </beans:beans> any help?

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  • So, "Are Design Patterns Missing Language Features"?

    - by Eduard Florinescu
    I saw the answer to this question: How does thinking on design patterns and OOP practices change in dynamic and weakly-typed languages? There it is a link to an article with an outspoken title: Are Design Patterns Missing Language Features. But where you can get snippets that seem very objective and factual and that can be verified from experience like: PaulGraham said "Peter Norvig found that 16 of the 23 patterns in Design Patterns were 'invisible or simpler' in Lisp." and a thing that confirms what I recently seen with people trying to simulate classes in javascript: Of course, nobody ever speaks of the "function" pattern, or the "class" pattern, or numerous other things that we take for granted because most languages provide them as built-in features. OTOH, programmers in a purely PrototypeOrientedLanguage? might well find it convenient to simulate classes with prototypes... I am taking into consideration also that design patterns are a communcation tool and because even with my limited experience participating in building applications I can see as an anti-pattern(ineffective and/or counterproductive) for example forcing a small PHP team to learn GoF patterns for small to medium intranet app, I am aware that scale, scope and purpose can determine what is effective and/or productive. I saw small commercial applications that mixed functional with OOP and still be maintainable, and I don't know if many would need for example in python to write a singleton but for me a simple module does the thing. patterns So are there studies or hands on experience shared that takes into consideration, all this, scale and scope of project, dynamics and size of the team, languages and technologies, so that you don't feel that a (difficult for some)design pattern is there just because there isn't a simpler way to do it or that it cannot be done by a language feature?

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  • Inheritance versus Composition in a business application

    - by ProfK
    I have a training management and tracking system, with a high level structure as follows: We have a Role1, e.g. Manager, Shift-boss, miner, etc. and a Candidate, training for that Role. The role has a list of courses and their subjects the candidate needs to complete to qualify for the role. Candidate has a TrainingHistory attribute, containing the courses and subjects they have completed, their results, and the date completed. Now I see it as a TrainingHistoryCourse is-a Course, extended to add DateCompleted etc. but something is nagging at me to rather use something like a TrainingHistoryRecord that has-a Course. How can I further analyse this to determine which pattern to use? Then, a Role has a list of RoleTask definitions that the Candidate must be observed practising, and a Candidate has a history of RoleTaskObservation objects recording their performance at these tasks. This is very similar to the course/subject requirement and history pattern for the candidate, except for one less hierarchical level, but, a RoleTaskObservation clearly does not have an is-a relationship with RoleTask, unless I block my nose and rather use ObservedRoleTask. I would prefer to use the same pattern for both subject/course and task/observation structures, but I think that would force me to adopt a composition pattern for TrainingHistoryCourse. What is the wisdom here? Always inherit where possible and validated by a solid is-a association, or always favour composition wherever possible? 1 Client specified this to be called JobTitle, but he isn't writing the app, and a JobTitle is only one attribute of a Role. Authorization roles are handled by the DevExpress framework and its customization hooks, so there would be very little little confusion between a business Role in my domain objects and an authorization role in lower level, framework code.

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  • Ruby Shoes for non-trivial apps

    - by marcof
    I've been taking a look at Ruby Shoes for GUI development with Ruby. So far, it's been a pretty good experience for making simple apps. However, I am quite worried about being able to write large scale applications with it. For example, how would I go about using MVP pattern with this framework ? For now, I have not been able to not make presentation concerns leak into the view because of the lack of some kind of "data binding". I have code that looks like this : Shoes.app do @view = SampleView.new @presenter = SamplePresenter.new @view @label = para @view.sample_property button "Update sample_property" do @presenter.update_sample_property end end Here, the call to @presenter.update_sample_property updates @view.sample_property but the label is not updated accordingly. For this to work, I would have to make @presenter.update_sample_property to return a string, and then call @label.text = return_value, but I think that would violate the MVP principle of not having presentation logic in the view. I'm used to work in .Net with the MVP pattern so I don't know if the pattern applies correctly to Shoes like I tried to do. Are there any ressources out there for making non-trivial apps with Shoes ? Especially using the MVP pattern or something similar ? EDIT : I took a look at the shoebox to see what other people have achieved with the framework. Though I did not look through it extensively, at first sight it seems like they are all simple projects with no real purposes.

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  • Patterns & Practices: Composite Services CTP2 is Public

    - by HernanDL
    Finally the last CTP and pre-release version for the Composite Services is out. There were quite a lot of changes since CTP1. We added many new samples and many enhancements to the repository (DB) which is now called Inventory in sync with SOA Patterns. Here is a brief list of the main changes according to the included documentations.   Changes and additions in this release This CTP release contains reusable source code and samples to illustrate implementation for the following patterns and scenarios: Repair and Resubmit – this pattern is implemented in ESB Toolkit 2.0 as part of Exception Management Framework (EMF). This code drop provides code sample how to implement this pattern for Windows AppFabric workflow service, using Exceptions Web Service and workflow activities to create fault message, which will be created in EMF database.  Analytic Tracing – this code drop contains reusable code and samples for implementing ETW tracing: event collector service and database that store collected events. This capability may be used for scenarios that need flexibility on how collected events are decoded and processed via extensibility points you can configure and implement:  plugins and event decoders with leveraging ETW tracing capabilities provided by the event collector service.   Inventory Centralization – this code drop contains service catalog database, web services and samples to show how to implement Metadata Centralization, Schema Centralization and Policy Centralization patterns.  Service Virtualization – we included sample for implementing this pattern using WCF routing service( which is part of .NET framework) and service metadata centralization capabilities to define routing service metadata in service catalog. Termination Notification – we included sample for implementing this pattern using sample WCF service and policy centralization capabilities provided by this CTP release.   You will also find many new videos that will be uploaded to the home page any time soon. Stay tunned for new posts regarding implemetation details and advanced customizations for custom policy exporters/importers and monitoring.

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  • Distinguishing between UI command & domain commands

    - by SonOfPirate
    I am building a WPF client application using the MVVM pattern that provides an interface on top of an existing set of business logic residing in a library which is shared with other applications. The business library followed a domain-driven architecture using CQRS to separate the read and write models (no event sourcing). The combination of technologies and patterns has brought up an interesting conundrum: The MVVM pattern uses the command pattern for handling user-interaction with the view models. .NET provides an ICommand interface which is implemented by most MVVM frameworks, like MVVM Light's RelayCommand and Prism's DelegateCommand. For example, the view model would expose a number of command objects as properties that are bound to the UI and respond when the user performs actions like clicking buttons. Many implementations of the CQRS use the command pattern to isolate and encapsulate individual behaviors. In my business library, we have implemented the write model as command / command-handler pairs. As such, when we want to do some work, such as create a new order, we 'issue' a command (CreateOrderCommand) which is routed to the command-handler responsible for executing the command. This is great, clearly explained in many sources and I am good with it. However, take this scenario: I have a ToolbarViewModel which exposes a CreateNewOrderCommand property. This ICommand object is bound to a button in the UI. When clicked, the UI command creates and issues a new CreateOrderCommand object to the domain which is handled by the CreateOrderCommandHandler. This is difficult to explain to other developers and I am finding myself getting tongue-tied because everything is a command. I'm sure I'm not the first developer to have patterns overlap like this where the naming/terminology also overlap. How have you approached distinguishing your commands used in the UI from those used in the domain? (Edit: I should mention that the business library is UI-agnostic, i.e. no UI technology-specific code exists, or will exists, in this library.)

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  • How to write regex in asp.net MVC 3 razor

    - by anirudha
    here is a small trick to write regex and exceptional code in MVC3. first trick is use @@ instead of @ it’s work don’ worry output goes @ not @@. second trick is that you can use <text></text> tag in MVC to use some code who give error because viewengine does not accept them. like var pattern = new RegExp(/^(("[\w-\s]+")|([\w-]+(?:\.[\w-]+)*)|("[\w-\s]+")([\w-]+(?:\.[\w-]+)*))(@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$)|(@\[?((25[0-5]\.|2[0-4][0-9]\.|1[0-9]{2}\.|[0-9]{1,2}\.))((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){2}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\]?$)/i);   this regex not work because it’s use @ so replace them to @@ e var pattern = new RegExp(/^(("[\w-\s]+")|([\w-]+(?:\.[\w-]+)*)|("[\w-\s]+")([\w-]+(?:\.[\w-]+)*))(@@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$)|(@@\[?((25[0-5]\.|2[0-4][0-9]\.|1[0-9]{2}\.|[0-9]{1,2}\.))((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){2}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\]?$)/i); now it will work. second way is that use text tag in MVC to make them work like <text> function isValidEmailAddress(emailAddress) { var pattern = new RegExp(/^(("[\w-\s]+")|([\w-]+(?:\.[\w-]+)*)|("[\w-\s]+")([\w-]+(?:\.[\w-]+)*))(@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$)|(@\[?((25[0-5]\.|2[0-4][0-9]\.|1[0-9]{2}\.|[0-9]{1,2}\.))((25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\.){2}(25[0-5]|2[0-4][0-9]|1[0-9]{2}|[0-9]{1,2})\]?$)/i); return pattern.test(emailAddress); } </text>

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  • Using Subjects to Deploy Queries Dynamically

    - by Roman Schindlauer
    In the previous blog posting, we showed how to construct and deploy query fragments to a StreamInsight server, and how to re-use them later. In today’s posting we’ll integrate this pattern into a method of dynamically composing a new query with an existing one. The construct that enables this scenario in StreamInsight V2.1 is a Subject. A Subject lets me create a junction element in an existing query that I can tap into while the query is running. To set this up as an end-to-end example, let’s first define a stream simulator as our data source: var generator = myApp.DefineObservable(     (TimeSpan t) => Observable.Interval(t).Select(_ => new SourcePayload())); This ‘generator’ produces a new instance of SourcePayload with a period of t (system time) as an IObservable. SourcePayload happens to have a property of type double as its payload data. Let’s also define a sink for our example—an IObserver of double values that writes to the console: var console = myApp.DefineObserver(     (string label) => Observer.Create<double>(e => Console.WriteLine("{0}: {1}", label, e)))     .Deploy("ConsoleSink"); The observer takes a string as parameter which is used as a label on the console, so that we can distinguish the output of different sink instances. Note that we also deploy this observer, so that we can retrieve it later from the server from a different process. Remember how we defined the aggregation as an IQStreamable function in the previous article? We will use that as well: var avg = myApp     .DefineStreamable((IQStreamable<SourcePayload> s, TimeSpan w) =>         from win in s.TumblingWindow(w)         select win.Avg(e => e.Value))     .Deploy("AverageQuery"); Then we define the Subject, which acts as an observable sequence as well as an observer. Thus, we can feed a single source into the Subject and have multiple consumers—that can come and go at runtime—on the other side: var subject = myApp.CreateSubject("Subject", () => new Subject<SourcePayload>()); Subject are always deployed automatically. Their name is used to retrieve them from a (potentially) different process (see below). Note that the Subject as we defined it here doesn’t know anything about temporal streams. It is merely a sequence of SourcePayloads, without any notion of StreamInsight point events or CTIs. So in order to compose a temporal query on top of the Subject, we need to 'promote' the sequence of SourcePayloads into an IQStreamable of point events, including CTIs: var stream = subject.ToPointStreamable(     e => PointEvent.CreateInsert<SourcePayload>(e.Timestamp, e),     AdvanceTimeSettings.StrictlyIncreasingStartTime); In a later posting we will show how to use Subjects that have more awareness of time and can be used as a junction between QStreamables instead of IQbservables. Having turned the Subject into a temporal stream, we can now define the aggregate on this stream. We will use the IQStreamable entity avg that we defined above: var longAverages = avg(stream, TimeSpan.FromSeconds(5)); In order to run the query, we need to bind it to a sink, and bind the subject to the source: var standardQuery = longAverages     .Bind(console("5sec average"))     .With(generator(TimeSpan.FromMilliseconds(300)).Bind(subject)); Lastly, we start the process: standardQuery.Run("StandardProcess"); Now we have a simple query running end-to-end, producing results. What follows next is the crucial part of tapping into the Subject and adding another query that runs in parallel, using the same query definition (the “AverageQuery”) but with a different window length. We are assuming that we connected to the same StreamInsight server from a different process or even client, and thus have to retrieve the previously deployed entities through their names: // simulate the addition of a 'fast' query from a separate server connection, // by retrieving the aggregation query fragment // (instead of simply using the 'avg' object) var averageQuery = myApp     .GetStreamable<IQStreamable<SourcePayload>, TimeSpan, double>("AverageQuery"); // retrieve the input sequence as a subject var inputSequence = myApp     .GetSubject<SourcePayload, SourcePayload>("Subject"); // retrieve the registered sink var sink = myApp.GetObserver<string, double>("ConsoleSink"); // turn the sequence into a temporal stream var stream2 = inputSequence.ToPointStreamable(     e => PointEvent.CreateInsert<SourcePayload>(e.Timestamp, e),     AdvanceTimeSettings.StrictlyIncreasingStartTime); // apply the query, now with a different window length var shortAverages = averageQuery(stream2, TimeSpan.FromSeconds(1)); // bind new sink to query and run it var fastQuery = shortAverages     .Bind(sink("1sec average"))     .Run("FastProcess"); The attached solution demonstrates the sample end-to-end. Regards, The StreamInsight Team

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  • How To Remove People and Objects From Photographs In Photoshop

    - by Eric Z Goodnight
    You might think that it’s a complicated process to remove objects from photographs. But really Photoshop makes it quite simple, even when removing all traces of a person from digital photographs. Read on to see just how easy it is. Photoshop was originally created to be an image editing program, and it excels at it. With hardly any Photoshop experience, any beginner can begin removing objects or people from their photos. Have some friends that photobombed an otherwise great pic? Tell them to say their farewells, because here’s how to get rid of them with Photoshop! Tools for Removing Objects Removing an object is not really “magical” work. Your goal is basically to cover up the information you don’t want in an image with information you do want. In this sample image, we want to remove the cigar smoking man, and leave the geisha. Here’s a couple of the tools that can be useful to work with when attempting this kind of task. Clone Stamp and Pattern Stamp Tool: Samples parts of your image from your background, and allows you to paint into your image with your mouse or stylus. Eraser and Brush Tools: Paint flat colors and shapes, and erase cloned layers of image information. Basic, down and dirty photo editing tools. Pen, Quick Selection, Lasso, and Crop tools: Select, isolate, and remove parts of your image with these selection tools. All useful in their own way. Some, like the pen tool, are nightmarishly tough on beginners. Remove a Person with the Clone Stamp Tool (Video) The video above uses the Clone Stamp tool to sample and paint with the background texture. It’s a simple tool to use, although it can be confusing, possibly counter-intuitive. Here’s some pointers, in addition to the video above. Select shortcut key to choose the Clone tool stamp from the Tools Panel. Always create a copy of your background layer before doing heavy edits by right clicking on the background in your Layers Panel and selecting “Duplicate.” Hold with the Clone Tool selected, and click anywhere in your image to sample that area. When you’re sampling an area, your cursor is “Aligned” with your sample area. When you paint, your sample area moves. You can turn the “Aligned” setting off by clicking the in the Options Panel at the top of your screen if you want. Change your brush size and hardness as shown in the video by right-clicking in your image. Use your lasso to copy and paste pieces of your image in order to cover up any parts that seem appropriate. Photoshop Magic with the “Content-Aware Fill” One of the hallmark features of CS5 is the “Content-Aware Fill.” Content aware fill can be an excellent shortcut to removing objects and even people in Photoshop, but it is somewhat limited, and can get confused. Here’s a basic rundown on how it works. Select an object using your Lasso tool, shortcut key . The Lasso works fine as this selection can be rough. Navigate to Edit > Fill, and select “Content-Aware,” as illustrated above, from the pull-down menu. It’s surprisingly simple. After some processing, Photoshop has done the work of removing the object for you. It takes a few moments, and it is not perfect, so be prepared to touch it up with some Copy-Paste, or some Clone stamp action. Content Aware Fill Has Its Limits Keep in mind that the Content Aware Fill is meant to be used with other techniques in mind. It doesn’t always perform perfectly, but can give you a great starting point. Take this image for instance. It is actually plausible to hide this figure and make this image look like he was never there at all. With a selection made with the Lasso tool, navigate to Edit > Fill and select “Content Aware” again. The result is surprisingly good, but as you can see, worthy of some touch up. With a result like this one, you’ll have to get your hands dirty with copy-paste to create believable lines in the background. With many photographs, Content Aware Fill will simply get confused and give you results you won’t be happy with. Additional Touch Up for Bad Background Textures with the Pattern Stamp Tool For the perfectionist, cleaning up the lumpy looking textures that the Clone Stamp can leave is fairly simple using the Pattern Stamp Tool. Sample an piece of your image with your Marquee Tool, shortcut key . Navigate to Edit > Define Pattern to create a new Pattern from your selection. Click OK to continue. Click and hold down on the Clone Stamp tool in your Tools Panel until you can select the Pattern Stamp Tool. Pick your new pattern from the Options at the top of your screen, in the Options Panel. Then simply right click in your image in order to pick as soft a brush as possible to paint with. Paint into your image until your background is as smooth as you want it to be, making your painted out object more and more invisible. If you get lines from your repeated texture, experiment turning the on and off and paint over them. In addition to this, simple use of the Crop Tool, shortcut , can recompose an image, making it look as if it never had another object in it at all. Combine these techniques to find a method that works best for your images. Have questions or comments concerning Graphics, Photos, Filetypes, or Photoshop? Send your questions to [email protected], and they may be featured in a future How-To Geek Graphics article. Image Credits: Geisha Kyoto Gion by Todd Laracuenta via Wikipedia, used under Creative Commons. Moai Rano raraku by Aurbina, in Public Domain. Chris Young visits Wrigley by TonyTheTiger, via Wikipedia, used under Creative Commons. Latest Features How-To Geek ETC Ask How-To Geek: How Can I Monitor My Bandwidth Usage? 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  • Async CTP (C# 5): How to make WCF work with Async CTP

    - by javarg
    If you have recently downloaded the new Async CTP you will notice that WCF uses Async Pattern and Event based Async Pattern in order to expose asynchronous operations. In order to make your service compatible with the new Async/Await Pattern try using an extension method similar to the following: WCF Async/Await Method public static class ServiceExtensions {     public static Task<DateTime> GetDateTimeTaskAsync(this Service1Client client)     {         return Task.Factory.FromAsync<DateTime>(             client.BeginGetDateTime(null, null),             ar => client.EndGetDateTime(ar));     } } The previous code snippet adds an extension method to the GetDateTime method of the Service1Client WCF proxy. Then used it like this (remember to add the extension method’s namespace into scope in order to use it): Code Snippet var client = new Service1Client(); var dt = await client.GetDateTimeTaskAsync(); Replace the proxy’s type and operation name for the one you want to await.

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  • Different callbacks for error or error as first argument?

    - by Florian Margaine
    We (and the JS SO chat room) had a talk with @rlemon some days ago about his Little-XHR library about error handling. Basically, we wanted to decide which error handling pattern should be used: xhr.get({ // Some parameters, and then success: function(data) {}, failure: function(data) {} }) Or: xhr.get({ // Some parameters, and then callback: function(err, data) {} }) One is more jQuery-like, while the other is more Node-like. Some say that the first pattern makes you think more about handling error. I think the opposite, since you may forget the other callback function, while the argument is always there on the second pattern. Any opinion/advantage/drawback about both these patterns?

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  • Sound Waves Visualized with a Chladni Plate and Colored Sand [Video]

    - by Jason Fitzpatrick
    This eye catching demonstration combines a Chladni Plate, four piles of colored sand, and a rubber mallet to great effect–watch as the plate vibrates pattern after pattern into the sand. A Chladni Plate, named after physicist Ernst Chladni, is a steel plate that vibrates when rubbed with a rubber ball-style mallet. Different size balls create different frequencies and each frequency creates a different pattern in the sand placed atop the plate. Watch the video above to see how rubber balls, large and small, change the patterns. [via Neatorama] Secure Yourself by Using Two-Step Verification on These 16 Web Services How to Fix a Stuck Pixel on an LCD Monitor How to Factory Reset Your Android Phone or Tablet When It Won’t Boot

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  • Code and Slides: Techniques, Strategies, and Patterns for Structuring JavaScript Code

    - by dwahlin
    This presentation was given at the spring 2012 DevConnections conference in Las Vegas and is based on my Structuring JavaScript Code course from Pluralsight. The goal of the presentation is to show how closures combined with code patterns can be used to provide structure to JavaScript code and make it more re-useable, maintainable, and less susceptible to naming conflicts.  Topics covered include: Closures Using Object literals Namespaces The Prototype Pattern The Revealing Module Pattern The Revealing Prototype Pattern View more of my presentations here. Sample code from the presentation can be found here. Check out the full-length course on the topic at Pluralsight.com.

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  • Modular enterprise architecture using MVC and Orchard CMS

    - by MrJD
    I'm making a large scale MVC application using Orchard. And I'm going to be separating my logic into modules. I'm also trying to heavily decouple the application for maximum extensibility and testability. I have a rudimentary understanding of IoC, Repository Pattern, Unit of Work pattern and Service Layer pattern. I've made myself a diagram. I'm wondering if it is correct and if there is anything I have missed regarding an extensible application. Note that each module is a separate project. Update So I have many UI modules that use the db module, that's why they've been split up. There are other services the UI modules will use. The UI modules have been split up because they will be made over time, independent of each other.

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  • How To Initialize Object Which May Be Used In Catch Clause?

    - by Onorio Catenacci
    I've seen this sort of pattern in code before: //pseudo C# code var exInfo = null; //Line A try { var p = SomeProperty; //Line B exInfo = new ExceptionMessage("The property was " + p); //Line C } catch(Exception ex) { exInfo.SomeOtherProperty = SomeOtherValue; //Line D } Usually the code is structured in this fashion because exInfo has to be visible outside of the try clause. The problem is that if an exception occurs on Line B, then exInfo will be null at Line D. The issue arises when something happens on Line B that must occur before exInfo is constructed. But if I set exInfo to a new Object at line A then memory may get leaked at Line C (due to "new"-ing the object there). Is there a better pattern for handling this sort of code? Is there a name for this sort of initialization pattern? By the way I know I could check for exInfo == null before line D but that seems a bit clumsy and I'm looking for a better approach.

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  • C# Open Source software that is useful for learning Design Patterns

    - by Fathom Savvy
    In college I took a class in Expert Systems. The language the book taught (CLIPS) was esoteric - Expert Systems: Principles and Programming, Fourth Edition. I remember having a tough time with it. So, after almost failing the class, I needed to create the most awesome Expert System for my final presentation. I chose to create an expert system that would calculate risk analysis for a person's retirement portfolio. In short, the system would provide the services normally performed by one's financial adviser. In other words, based on personality, age, state of the macro economy, and other factors, should one's portfolio be conservative, moderate, or aggressive? In the appendix of the book (or on the CD-ROM), there was this in-depth example program for something unrelated to my presentation. Over my break, I read and re-read every line of that program until I understood it to the letter. Even though it was unrelated, I learned more than I ever could by reading all of the chapters. My presentation turned out to be pretty damn good and I received praises from my professor and classmates. So, the moral of the story is..., by understanding other people's code, you can gain greater insight into a language/paradigm than by reading canonical examples. Still, to this day, I am having trouble with everyday design patterns such as the Factory Pattern. I would like to know if anyone could recommend open source software that would help me understand the Gang of Four design patterns, at the very least. I have read the books, but I'm having trouble writing code for the concepts in the real world. Perhaps, by studying code used in today's real world applications, it might just "click". I realize a piece of software may only implement one kind of design pattern. But, if the pattern is an implementation you think is good for learning, and you know what pattern to look for within the source, I'm hoping you can tell me about it. For example, the System.Linq.Expressions namespace has a good example of the Visitor Pattern. The client calls Expression.Accept(new ExpressionVisitor()), which calls ExpressionVisitor (VisitExtension), which calls back to Expression (VisitChildren), which then calls Expression (Accept) again - wooah, kinda convoluted. The point to note here is that VisitChildren is a virtual method. Both Expression and those classes derived from Expression can implement the VisitChildren method any way they want. This means that one type of Expression can run code that is completely different from another type of derived Expression, even though the ExpressionVisitor class is the same in the Accept method. (As a side note Expression.Accept is also virtual). In the end, the code provides a real world example that you won't get in any book because it's kinda confusing. To summarize, If you know of any open source software that uses a design pattern implementation you were impressed by, please list it here. I'm sure it will help many others besides just me. public class VisitorPatternTest { public void Main() { Expression normalExpr = new Expression(); normalExpr.Accept(new ExpressionVisitor()); Expression binExpr = new BinaryExpression(); binExpr.Accept(new ExpressionVisitor()); } } public class Expression { protected internal virtual Expression Accept(ExpressionVisitor visitor) { return visitor.VisitExtension(this); } protected internal virtual Expression VisitChildren(ExpressionVisitor visitor) { if (!this.CanReduce) { throw Error.MustBeReducible(); } return visitor.Visit(this.ReduceAndCheck()); } public virtual Expression Visit(Expression node) { if (node != null) { return node.Accept(this); } return null; } public Expression ReduceAndCheck() { if (!this.CanReduce) { throw Error.MustBeReducible(); } Expression expression = this.Reduce(); if ((expression == null) || (expression == this)) { throw Error.MustReduceToDifferent(); } if (!TypeUtils.AreReferenceAssignable(this.Type, expression.Type)) { throw Error.ReducedNotCompatible(); } return expression; } } public class BinaryExpression : Expression { protected internal override Expression Accept(ExpressionVisitor visitor) { return visitor.VisitBinary(this); } protected internal override Expression VisitChildren(ExpressionVisitor visitor) { return CreateDummyExpression(); } protected internal Expression CreateDummyExpression() { Expression dummy = new Expression(); return dummy; } } public class ExpressionVisitor { public virtual Expression Visit(Expression node) { if (node != null) { return node.Accept(this); } return null; } protected internal virtual Expression VisitExtension(Expression node) { return node.VisitChildren(this); } protected internal virtual Expression VisitBinary(BinaryExpression node) { return ValidateBinary(node, node.Update(this.Visit(node.Left), this.VisitAndConvert<LambdaExpression>(node.Conversion, "VisitBinary"), this.Visit(node.Right))); } }

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  • How to test robots.txt in googlebot to find out what is being indexed

    - by Amar Jarubula
    This question is a continuation for this answer How to check if googlebot will index a given url? As was told I did go to the Webmaster Tools and tested contents of my robots.txt file. However this is just giving me the info if that content is good enough or not. However for my scenario I need to test whether disallowing some patterns is being indexed or not. For example I have something like this below in my robots.txt disallow:/pattern* My understanding is the URLs with word pattern should not crawled, but how do I test this pattern is enforced while indexing the website?

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  • Design Patterns - Service Layer

    - by garfbradaz
    I currently reading a lot about Design Patterns and I have been watching various Pluralsight videos from their library. Now so far I have learnt the following: Repository Pattern Unit of Work Pattern Abstract Factory Pattern Reading the awesome "DI in .NET" book Now I read lot about Services and Service Layers and wanted some advice about the best place to read up and learn about these. I presume this fits into Domain Driven Design and I should start there? The term "Service" just seem to be used widely within IT and it can be confusing the exact meaning. So my questions is: What is the Service Layer Where is the best place to learn about them. I know there are probably tonnes of interweb/books/blogs on the subject, but some good areas to start from would be nice. If I'm being too vague, let me know.

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  • Rails - asynchronous tasks, forked processes, best practices

    - by LisaPatton
    I'm using a Observer on my classes. When one of the records is created/updated I need to notfify another service (via a URL call). What is the best way to do this to avoid slowing down my class? Would using a gem liked delayed_job be overkill? In my Observer's after_update() / after_create() I just want to launch a thread that calls the URL...

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  • Flex: Constant strings in metadata

    - by Daniel Engmann
    I have something like public class Controller { [Observer("fetchEmployeesEvent")] public function fetchEmployees() : void { //doSomething } } and I want something like public class Controller { public static const FETCH_EMPLOYEES_EVENT : String = "fetchEmployeesEvent"; [Observer(FETCH_EMPLOYEES_EVENT)] public function fetchEmployees() : void { //doSomething } } My problem is that only the first code snippet works. Flex seems to ignore the constant FETCH_EMPLOYEES_EVENT in the metadata-tag. My question is: Is it somehow possible to use constant strings in metadata?

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  • Violation of the DRY Principle

    - by Onorio Catenacci
    I am sure there's a name for this anti-pattern somewhere; however I am not familiar enough with the anti-pattern literature to know it. Consider the following scenario: or0 is a member function in a class. For better or worse, it's heavily dependent on class member variables. Programmer A comes along and needs functionality like or0 but rather than calling or0, Programmer A copies and renames the entire class. I'm guessing that she doesn't call or0 because, as I say, it's heavily dependent on member variables for its functionality. Or maybe she's a junior programmer and doesn't know how to call it from other code. So now we've got or0 and c0 (c for copy). I can't completely fault Programmer A for this approach--we all get under tight deadlines and we hack code to get work done. Several programmers maintain or0 so it's now version orN. c0 is now version cN. Unfortunately most of the programmers that maintained the class containing or0 seemed to be completely unaware of c0--which is one of the strongest arguments I can think of for the wisdom of the DRY principle. And there may also have been independent maintainance of the code in c. Either way it appears that or0 and c0 were maintained independent of each other. And, joy and happiness, an error is occurring in cN that does not occur in orN. So I have a few questions: 1.) Is there a name for this anti-pattern? I've seen this happen so often I'd find it hard to believe this is not a named anti-pattern. 2.) I can see a few alternatives: a.) Fix orN to take a parameter that specifies the values of all the member variables it needs. Then modify cN to call orN with all of the needed parameters passed in. b.) Try to manually port fixes from orN to cN. (Mind you I don't want to do this but it is a realistic possibility.) c.) Recopy orN to cN--again, yuck but I list it for sake of completeness. d.) Try to figure out where cN is broken and then repair it independently of orN. Alternative a seems like the best fix in the long term but I doubt the customer will let me implement it. Never time or money to fix things right but always time and money to repair the same problem 40 or 50 times, right? Can anyone suggest other approaches I may not have considered? If you were in my place, which approach would you take? If there are other questions and answers here along these lines, please post links to them. I don't mind removing this question if it's a dupe but my searching hasn't turned up anything that addresses this question yet. EDIT: Thanks everyone for all the thoughtful responses. I asked about a name for the anti-pattern so I could research it further on my own. I'm surprised this particular bad coding practice doesn't seem to have a "canonical" name for it.

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  • how to parse a Date string to java.Date

    - by hguser
    Hi: I have a date string and I wang to parse it to normal date use the java Date API,the following is my code: public static void main(String[] args) { String date="2010-10-02T12:23:23Z"; String pattern="yyyy-MM-ddThh:mm:ssZ"; SimpleDateFormat sdf=new SimpleDateFormat(pattern); try { Date d=sdf.parse(date); System.out.println(d.getYear()); } catch (ParseException e) { // TODO Auto-generated catch block e.printStackTrace(); } } However I got a exception:java.lang.IllegalArgumentException: Illegal pattern character 'T' So I wonder if i have to split the string and parse it manually? BTW, I have tried to add a single quote character on either side of the T: String pattern="yyyy-MM-dd'T'hh:mm:ssZ"; It also does not work.

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  • Using LIKE operator in LINQ to Entity

    - by Draconic
    Hi, everybody! Currently in our project we are using Entity Framework and LINQ. We want to create a search feature where the Client fills different filters but he isn't forced to. To do this "dynamic" query in LINQ, we thought about using the Like operator, searching either for the field, or "%" to get everything if the user didn't fill that field. The joke's on us when we discovered it didn't support Like. After some searching, we read several answers where it's sugested to use StartsWith, but it's useless for us. Is the only solution using something like: ObjectQuery<Contact> contacts = db.Contacts; if (pattern != "") { contacts = contacts.Where(“it.Name LIKE @pattern”); contacts.Parameters.Add(new ObjectParameter(“pattern”, pattern); } However, we'd like to stick with linq only. Happy coding!

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  • singleton vs factory?

    - by fayer
    i've got 3 Log classes that all implements iLog interface: DatabaseLog FileLog ScreenLog there can only be one instance of them. initially i though of using single pattern for each class but then i thought why not use a factory for instantiation instead, cause then i wont have to create single pattern for each one of them and for all future Log classes. and maybe someone would want them as multiple objects in the future. so my questions is: should i use factory or singleton pattern here?

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