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  • Parallel Class/Interface Hierarchy with the Facade Design Pattern?

    - by Mike G
    About a third of my code is wrapped inside a Facade class. Note that this isn't a "God" class, but actually represents a single thing (called a Line). Naturally, it delegates responsibilities to the subsystem behind it. What ends up happening is that two of the subsystem classes (Output and Timeline) have all of their methods duplicated in the Line class, which effectively makes Line both an Output and a Timeline. It seems to make sense to make Output and Timeline interfaces, so that the Line class can implement them both. At the same time, I'm worried about creating parallel class and interface structures. You see, there are different types of lines AudioLine, VideoLine, which all use the same type of Timeline, but different types of Output (AudioOutput and VideoOutput, respectively). So that would mean that I'd have to create an AudioOutputInterface and VideoOutputInterface as well. So not only would I have to have parallel class hierarchy, but there would be a parallel interface hierarchy as well. Is there any solution to this design flaw? Here's an image of the basic structure (minus the Timeline class, though know that each Line has-a Timeline): NOTE: I just realized that the word 'line' in Timeline might make is sound like is does a similar function as the Line class. They don't, just to clarify.

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  • it is a good approach to implement dependency injection in a desktop app?

    - by luis_laurent
    Well, the thing is that I am just about to create a Desktop App (with .NET windows forms) And now I just wonder if it would be really a wise choise to use any IoC (StructureMap,Ninject,Spring .Net), I have used them before for Asp.Net web applications but what makes me doubt now is the fact that working with windows forms my business entities will persist when I navigate through tabs and unlike than web forms or mvc apps where it would be necesary to inject my business entity for every new request that is performed, I mean this because of the Asp.Net page life cycle where is performed the initialization and controls instantiation. Maybe I am misunderstanding the point of using an IoC, so please tell me what do you think would be a better choise?

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  • I studied electrical engineering. Can I work as a developer? [closed]

    - by FailedDev
    A while ago I finished my Msc in Electrical Engineering and started working as an engineering consultant where I mostly do development work. I am good at picking up languages/technologies tools. I have fiddled with C/C++/C#/perl/ant/bash/html/css etc. Although I have never had a complain for my work, rather the contrary, I just feel that some day, someone will ask me a real hard task which would maybe seem rather trivial for a computer scientist but hard for me. Should I read/do something to become a better developer. Should I pick up a book about design patterns or algorithms for example? Is this normal that I have this kind of "fear"? Sorry if this is the wrong place to post this question. Please notify me so I can close it if this is the case.

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  • Dealing with coworkers when developing, need advice [closed]

    - by Yippie-Kai-Yay
    I developed our current project architecture and started developing it on my own (reaching something like, revision 40). We're developing a simple subway routing framework and my design seemed to be done extremely well - several main models, corresponding views, main logic and data structures were modeled "as they should be" and fully separated from rendering, algorithmic part was also implemented apart from the main models and had a minor number of intersection points. I would call that design scalable, customizable, easy-to-implement, interacting mostly based on the "black box interaction" and, well, very nice. Now, what was done: I started some implementations of the corresponding interfaces, ported some convenient libraries and wrote implementation stubs for some application parts. I had the document describing coding style and examples of that coding style usage (my own written code). I forced the usage of more or less modern C++ development techniques, including no-delete code (wrapped via smart pointers) and etc. I documented the purpose of concrete interface implementations and how they should be used. Unit tests (mostly, integration tests, because there wasn't a lot of "actual" code) and a set of mocks for all the core abstractions. I was absent for 12 days. What do we have now (the project was developed by 4 other members of the team): 3 different coding styles all over the project (I guess, two of them agreed to use the same style :), same applies to the naming of our abstractions (e.g CommonPathData.h, SubwaySchemeStructures.h), which are basically headers declaring some data structures. Absolute lack of documentation for the recently implemented parts. What I could recently call a single-purpose-abstraction now handles at least 2 different types of events, has tight coupling with other parts and so on. Half of the used interfaces now contain member variables (sic!). Raw pointer usage almost everywhere. Unit tests disabled, because "(Rev.57) They are unnecessary for this project". ... (that's probably not everything). Commit history shows that my design was interpreted as an overkill and people started combining it with personal bicycles and reimplemented wheels and then had problems integrating code chunks. Now - the project still does only a small amount of what it has to do, we have severe integration problems, I assume some memory leaks. Is there anything possible to do in this case? I do realize that all my efforts didn't have any benefit, but the deadline is pretty soon and we have to do something. Did someone have a similar situation? Basically I thought that a good (well, I did everything that I could) start for the project would probably lead to something nice, however, I understand that I'm wrong. Any advice would be appreciated, sorry for my bad english.

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  • Why would more CPU cores on virtual machine slow compile times?

    - by Sid
    [edit#2] If anyone from VMWare can hit me up with a copy of VMWare Fusion, I'd be more than happy to do the same as a VirtualBox vs VMWare comparison. Somehow I suspect the VMWare hypervisor will be better tuned for hyperthreading (see my answer too) I'm seeing something curious. As I increase the number of cores on my Windows 7 x64 virtual machine, the overall compile time increases instead of decreasing. Compiling is usually very well suited for parallel processing as in the middle part (post dependency mapping) you can simply call a compiler instance on each of your .c/.cpp/.cs/whatever file to build partial objects for the linker to take over. So I would have imagined that compiling would actually scale very well with # of cores. But what I'm seeing is: 8 cores: 1.89 sec 4 cores: 1.33 sec 2 cores: 1.24 sec 1 core: 1.15 sec Is this simply a design artifact due to a particular vendor's hypervisor implementation (type2:virtualbox in my case) or something more pervasive across more VMs to make hypervisor implementations more simpler? With so many factors, I seem to be able to make arguments both for and against this behavior - so if someone knows more about this than me, I'd be curious to read your answer. Thanks Sid [edit:addressing comments] @MartinBeckett: Cold compiles were discarded. @MonsterTruck: Couldn't find an opensource project to compile directly. Would be great but can't screwup my dev env right now. @Mr Lister, @philosodad: Have 8 hw threads, using VirtualBox, so should be 1:1 mapping without emulation @Thorbjorn: I have 6.5GB for the VM and a smallish VS2012 project - it's quite unlikely that I'm swapping in/out trashing the page file. @All: If someone can point to an open source VS2010/VS2012 project, that might be a better community reference than my (proprietary) VS2012 project. Orchard and DNN seem to need environment tweaking to compile in VS2012. I really would like to see if someone with VMWare Fusion also sees this (for VMWare vs VirtualBox compartmentalization) Test details: Hardware: Macbook Pro Retina CPU : Core i7 @ 2.3Ghz (quad core, hyper threaded = 8 cores in windows task manager) Memory : 16 GB Disk : 256GB SSD Host OS: Mac OS X 10.8 VM type: VirtualBox 4.1.18 (type 2 hypervisor) Guest OS: Windows 7 x64 SP1 Compiler: VS2012 compiling a solution with 3 C# Azure projects Compile times measure by VS2012 plugin called 'VSCommands' All tests run 5 times, first 2 runs discarded, last 3 averaged

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  • Ideal programming language learning sequence? [closed]

    - by Gulshan
    What do you think? What is the ideal programming language learning sequence which will cover most of the heavily used languages and paradigms today as well as help to grasp common programming basics, ideas and practices? You can even suggest learning sequence for paradigms rather than languages. N.B. : This is port of the question I asked in stackoverflow and was closed for being subjective and argumentative.

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  • What is the best way to pass data into an API from a website?

    - by Chris Wakoksi
    My main objective is to create a User Interface in order to provision(change the status: activate, deactivate, or suspend) modems. I have received a SOAP developer's guide to the specific type of modem that helps out with the specific values that I need to pass into Iridium's WSDL but I cannot figure out how to do this from a webpage I have created using HTML/CSS, and PHP? I have been told by others that I need to know the portal. I have no idea what that means. I am a beginner programmer who has learned programming for this project. Any suggestions as to how to pass my data into the provisioning API?

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  • Origin of common list-processing function names

    - by Heatsink
    Some higher-order functions for operating on lists or arrays have been repeatedly adopted or reinvented. The functions map, fold[l|r], and filter are found together in several programming languages, such as Scheme, ML, and Python, that don't seem to have a common ancestor. I'm going with these three names to keep the question focused. To show that the names are not universal, here is a sampling of names for equivalent functionality in other languages. C++ has transform instead of map and remove_if instead of filter (reversing the meaning of the predicate). Lisp has mapcar instead of map, remove-if-not instead of filter, and reduce instead of fold (Some modern Lisp variants have map but this appears to be a derived form.) C# uses Select instead of map and Where instead of filter. C#'s names came from SQL via LINQ, and despite the name changes, their functionality was influenced by Haskell, which was itself influenced by ML. The names map, fold, and filter are widespread, but not universal. This suggests that they were borrowed from an influential source into other contemporary languages. Where did these function names come from?

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  • Is Moving Entity Framework objects over a webservice really the best way?

    - by aceinthehole
    I've inherited a .NET project that has close to 2 thousand clients out in the field that need to push data periodically up to a central repository. The clients wake up and attempt to push the data up via a series of WCF webservices where they are passing each entity framework entity as parameter. Once the service receives this object, it preforms some business logic on the data, and then turns around and sticks it in it's own database that mirrors the database on the client machines. The trick is, is that this data is being transmitted over a metered connection, which is very expensive. So optimizing the data is a serious priority. Now, we are using a custom encoder that compresses the data (and decompresses it on the other end) while it is being transmitted, and this is reducing the data footprint. However, the amount of data that the clients are using, seem ridiculously large, given the amount of information that is actually being transmitted. It seems me that entity framework itself may be to blame. I'm suspecting that the objects are very large when serialized to be sent over wire, with a lot context information and who knows what else, when what we really need is just the 'new' inserts. Is using the entity framework and WCF services as we have done so far the correct way, architecturally, of approaching this n-tiered, asynchronous, push only problem? Or is there a different approach, that could optimize the data use?

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  • Should I use JavaFx properties?

    - by Mike G
    I'm usually very careful to keep my Model, View, and Controller code separate. The thing is JavaFx properties are so convenient to bind them all together. The issue is that it makes my entire code design dependent on JavaFx, which I feel I should not being doing. I should be able to change the view without changing too much of the model and controller. So should I ignore the convenience of JavaFx properties, or should I embrace them and the fact that it reduces my codes flexibility.

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  • Indefinite loops where the first time is different

    - by George T
    This isn't a serious problem or anything someone has asked me to do, just a seemingly simple thing that I came up with as a mental exercise but has stumped me and which I feel that I should know the answer to already. There may be a duplicate but I didn't manage to find one. Suppose that someone asked you to write a piece of code that asks the user to enter a number and, every time the number they entered is not zero, says "Error" and asks again. When they enter zero it stops. In other words, the code keeps asking for a number and repeats until zero is entered. In each iteration except the first one it also prints "Error". The simplest way I can think of to do that would be something like the folloing pseudocode: int number = 0; do { if(number != 0) { print("Error"); } print("Enter number"); number = getInput(); }while(number != 0); While that does what it's supposed to, I personally don't like that there's repeating code (you test number != 0 twice) -something that should generally be avoided. One way to avoid this would be something like this: int number = 0; while(true) { print("Enter number"); number = getInput(); if(number == 0) { break; } else { print("Error"); } } But what I don't like in this one is "while(true)", another thing to avoid. The only other way I can think of includes one more thing to avoid: labels and gotos: int number = 0; goto question; error: print("Error"); question: print("Enter number"); number = getInput(); if(number != 0) { goto error; } Another solution would be to have an extra variable to test whether you should say "Error" or not but this is wasted memory. Is there a way to do this without doing something that's generally thought of as a bad practice (repeating code, a theoretically endless loop or the use of goto)? I understand that something like this would never be complex enough that the first way would be a problem (you'd generally call a function to validate input) but I'm curious to know if there's a way I haven't thought of.

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  • Is loose coupling w/o use cases an anti-pattern?

    - by dsimcha
    Loose coupling is, to some developers, the holy grail of well-engineered software. It's certainly a good thing when it makes code more flexible in the face of changes that are likely to occur in the foreseeable future, or avoids code duplication. On the other hand, efforts to loosely couple components increase the amount of indirection in a program, thus increasing its complexity, often making it more difficult to understand and often making it less efficient. Do you consider a focus on loose coupling without any use cases for the loose coupling (such as avoiding code duplication or planning for changes that are likely to occur in the foreseeable future) to be an anti-pattern? Can loose coupling fall under the umbrella of YAGNI?

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  • What are the essential things one needs to know about UML?

    - by Hanno Fietz
    I want my scribbles of a program's design and behaviour to become more streamlined and have a common language with other developers. I looked at UML and in principle it seems to be what I'm looking for, but it seems to be overkill. The information I found online also seems very bloated and academic. How can I understand UML in plain-English way, enough to be able to explain it to my colleagues? What are the canonical resources for understanding UML at a ground level?

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  • Why can we delete some built-in properties of global object?

    - by demix
    I'm reading es5 these days and find that [[configurable]] attribute in some built-in properties of global object is set to true which means we can delete these properties. For example: the join method of Array.prototype object have attributes {[[Writable]]:true, [[Enumerable]]: false, [[Configurable]]: true} So we can easily delete the join method for Array like: delete Array.prototype.join; alert([1,2,3].join); The alert will display undefined in my chromium 17,firefox 9 ,ie 10,even ie6; In Chrome 15 & safari 5.1.1 the [[configurable]] attribute is set to true and delete result is also true but the final result is still function(){[native code]}. Seems like this is a bug and chromium fix it. I haven't notice that before. In my opinion, delete built-in functions in user's code is dangerous, and will bring out so many bugs when working with others.So why ECMAScript make this decision?

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  • Ninject/DI: How to correctly pass initialisation data to injected type at runtime

    - by MrLane
    I have the following two classes: public class StoreService : IStoreService { private IEmailService _emailService; public StoreService(IEmailService emailService) { _emailService = emailService; } } public class EmailService : IEmailService { } Using Ninject I can set up bindings no problem to get it to inject a concrete implementation of IEmailService into the StoreService constructor. StoreService is actually injected into the code behind of an ASP.NET WebForm as so: [Ninject.Inject] public IStoreService StoreService { get; set; } But now I need to change EmailService to accept an object that contains SMTP related settings (that are pulled from the ApplicationSettings of the Web.config). So I changed EmailService to now look like this: public class EmailService : IEmailService { private SMTPSettings _smtpSettings; public void SetSMTPSettings(SMTPSettings smtpSettings) { _smtpSettings = smtpSettings; } } Setting SMTPSettings in this way also requires it to be passed into StoreService (via another public method). This has to be done in the Page_Load method in the WebForms code behind (I only have access to the Settings class in the UI layer). With manual/poor mans DI I could pass SMTPSettings directly into the constructor of EmailService and then inject EmailService into the StoreService constructor. With Ninject I don't have access to the instances of injected types outside of the objects they are injected to, so I have to set their data AFTER Ninject has already injected them via a separate public setter method. This to me seems wrong. How should I really be solving this scenario?

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  • What is considered to be a "modification" of sources under the BSD license?

    - by Den
    I have a question about the 3-clause BSD license based on it's Wiki description. It states: Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: ... What is understood by "modification"? Specifically I am interested whether any/all of the following is considered as such modification: 1) reading the original sources and then re-implementing; 2) reading the original sources, waiting for a year and then re-implementing something based on whatever you could remember; 3) direct and very significant "complete" refactoring of the original sources.

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  • Is it safer to use the same IV all times data are encrypted, or use a dynamic IV that is sent together the encrypted text? [closed]

    - by kiamlaluno
    When encrypting data that is then send to a server, is it better to always use the same IV, which is already known from the receiving server, or use a dynamic IV that is then sent to the receiving server? I am referring to the case the remote server receives data from another server, or from a client application, and executes operations on a database table, in the table row identified by the received data. Which of the following PHP snippets is preferable? $iv = mcrypt_create_iv(mcrypt_enc_get_iv_size($td), MCRYPT_RAND); $ks = mcrypt_enc_get_key_size($td); $key = substr(md5('very secret key'), 0, $ks); mcrypt_generic_init($td, $key, $iv); $encrypted = mcrypt_generic($td, 'This is very important data'); send_encripted_data(combine_iv_encrypted_text($iv, $encrypted)); $ks = mcrypt_enc_get_key_size($td); $key = substr(md5('very secret key'), 0, $ks); mcrypt_generic_init($td, $key, $iv); send_encripted_data(mcrypt_generic($td, 'This is very important data')); In which way is one of the snippets more vulnerable than the other one?

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  • How to make the switch to C++11?

    - by Overv
    I've been programming in C++ for a while now, but mostly thinks centered around the low-level features of C++. By that I mean mostly working with pointers and raw arrays. I think this behavior is known as using C++ as C with classes despite me only having tried C recently for the first time. I was pleasantly surprised how languages like C# and Java hide these details away in convenient standard library classes like Dictionaries and Lists. I'm aware that the C++ standard library has many convenience containers like vectors, maps and strings as well and C++11 only adds to this by having std:: array and ranged loops. How do I best learn to make use of these modern language features and which are suitable for which moments? Is it correct that software engineering in C++ nowadays I'd mostly free of manual memory management? Lastly, which compiler should I use to make the most of the new standard? Visual Studio has excellent debugging tools, but even VS2012 seems to have terrible C++11 support.

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  • Should I use structure from a core library graphic toolkit in my domain?

    - by Laurent Bourgault-Roy
    In java (and many other programming language), there are often structure to deal with graphic element : Colour, Shape, etc. Those are most often in a UI toolkit and thus have a relatively strong coupling with UI element. Now, in the domain of my application, we often deal with colour, shape, etc, to display statistic information on an element. Right now all we do with it is display/save those element with little or no behaviour. Would it make sense to avoid "reinventing the wheel" and directly use the structures in java.awt.* or should I make my own element and avoid a coupling to this toolkit? Its not like those element are going away anytime soon (they are part of the core java library after all), but at the same time it feel weird to import java.awt.* server side. I have no problem using java.util.List everywhere. Should I feel different about those class? What would be the "recommended" practice in that case?

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  • Steps to create a solution for a problem

    - by Mr_Green
    I am a trainee. According to my teacher, he says that to solve a problem we should go with steps to solve it like Create Algorithm (optional) Create a Datatable: By analyzing the problem, create main concepts in those problem as columns and the related issues in the main concept as rows. Create a Flowchart based on the Datatable. (when creating flow chart, think that you are in that situation and design it in your brain) By seeing the Flowchart, solve the problem. These steps should always consider by a programmer if he/she wants to become a Software designer (not programmer). Because the above approach gives an efficient way of finding solution to a problem even the problem is small. According to him, this way of approach also works in real time scenario's. My question is: Is this really an efficient way? please share also your thoughts. Keeping beside my question I just want to share some thoughts of my teacher with you who is a good mentor for me.

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  • Why does a computer science degree matter to a professional programmer?

    - by P.Brian.Mackey
    I have a degree in computer science. It has been great for opening doors, getting a job. As far as helping me in the professional field of C# .NET programming (the most popular platform and language in the area I work if not the entire united states on hands down the most popular OS in the world) its hardly useful. Why do you think it helps you as a programmer in your professional career (outside spouting off to prims algorithm to impress some interviewer)? In today's world adaptation, a quick mind, strong communication, OO and fundamental design skills enable a developer to write software that a customer will accept. These skills are only skimmed over in the cs program. In my mind, reading a 500 page C# book by Wrox offers far more useable a skillset than 4 years of the comp sci math blaster courses. Many disagree. So, why does a computer science degree matter?

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  • SpringMvc java.lang.NullPointerException When Posting Form To Server [closed]

    - by dev_darin
    I have a form with a user name field on it when i tab out of the field i use a RESTFUL Web Service that makes a call to a handler method in the controller. The method makes a call to a DAO class that checks the database if the user name exists. This works fine, however when the form is posted to the server i call the same exact function i would call in the handler method however i get a java.lang.NullPointerException when it accesses the class that makes a call to the DAO object. So it does not even access the DAO object the second time. I have exception handlers around the calls in all my classes that makes calls. Any ideas as to whats happening here why i would get the java.lang.NullPointerException the second time the function is called.Does this have anything to do with Spring instantiating DAO classes using a Singleton method or something to that effect? What can be done to resolve this? This is what happens the First Time The Method is called using the Web Service(this is suppose to happen): 13011 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - Inside jdbcOfficersDAO 13031 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL query 13034 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [SELECT userName FROM crimetrack.tblofficers WHERE userName = ?] 13071 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource 13496 [http-8084-2] DEBUG org.springframework.jdbc.core.StatementCreatorUtils - Setting SQL statement parameter value: column index 1, parameter value [adminz], value class [java.lang.String], SQL type unknown 13534 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource 13537 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - No username was found in exception 13537 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz does NOT exist The Second time When The Form Is 'Post' and a validation method handles the form and calls the same method the web service would call: 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - Inside Do UserNameExist about to validate with username : adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz EXCEPTION OCCURED java.lang.NullPointerException ValidateUserNameManager.java public class ValidateUserNameManager implements ValidateUserNameIFace { private OfficersDAO officerDao; private final Logger logger = Logger.getLogger(getClass()); public boolean DoesUserNameExist(String userName) throws Exception { logger.info("Inside Do UserNameExist about to validate with username : " + userName); try{ if(officerDao.OfficerExist(userName) == true){ logger.info("UserName :" + userName + " does exist"); return true; }else{ logger.info("UserName :" + userName + " does NOT exist"); return false; } }catch(Exception e){ logger.info("UserName :" + userName + " EXCEPTION OCCURED " + e.toString()); return false; } } /** * @return the officerDao */ public OfficersDAO getOfficerDao() { return officerDao; } /** * @param officerdao the officerDao to set */ public void setOfficerDao(OfficersDAO officerDao) { this.officerDao = officerDao; } } JdbcOfficersDAO.java public boolean OfficerExist(String userName){ String dbUserName; try{ logger.info("Inside jdbcOfficersDAO"); String sql = "SELECT userName FROM crimetrack.tblofficers WHERE userName = ?"; try{ dbUserName = (String)getJdbcTemplate().queryForObject(sql, new Object[]{userName},String.class); logger.info("Just Returned from database"); }catch(Exception e){ logger.info("No username was found in exception"); return false; } if(dbUserName == null){ logger.info("Database did not find any matching records"); } logger.info("after JdbcTemplate"); if (dbUserName.equals(userName)) { logger.info("User Name Exists"); return true; }else{ logger.info("User Name Does NOT Exists"); return false; } }catch(Exception e){ logger.info("Exception Message in JdbcOfficersDAO is "+e.getMessage()); return false; } } OfficerRegistrationValidation.java public class OfficerRegistrationValidation implements Validator{ private final Logger logger = Logger.getLogger(getClass()); private ValidateUserNameManager validateUserNameManager; public boolean supports(Class<?> clazz) { return Officers.class.equals(clazz); } public void validate(Object target, Errors errors) { Officers officer = (Officers) target; if (officer.getUserName() == null){ errors.rejectValue("userName", "userName.required"); }else{ String userName = officer.getUserName(); logger.info("UserName is not null so going to check if its valid for :" + userName); try { logger.info("User Name in try.....catch block is " + userName); if (validateUserNameManager.DoesUserNameExist(userName)== true){ errors.rejectValue("userName", "userName.exist"); } } catch (Exception e) { logger.info("Error Occured When validating UserName"); errors.rejectValue("userName", "userName.error"); } } if(officer.getPassword()== null){ errors.rejectValue("password", "password.required"); } if(officer.getPassword2()== null){ errors.rejectValue("password2", "password2.required"); } if(officer.getfName() == null){ errors.rejectValue("fName","fName.required"); } if(officer.getlName() == null){ errors.rejectValue("lName", "lName.required"); } if (officer.getoName() == null){ errors.rejectValue("oName", "oName.required"); } if (officer.getEmailAdd() == null){ errors.rejectValue("emailAdd", "emailAdd.required"); } if (officer.getDob() == null){ errors.rejectValue("dob", "dob.required"); } if (officer.getGenderId().equals("A")){ errors.rejectValue("genderId","genderId.required"); } if(officer.getDivisionNo() == 1){ errors.rejectValue("divisionNo", "divisionNo.required"); } if(officer.getPositionId() == 1){ errors.rejectValue("positionId", "positionId.required"); } if (officer.getStartDate() == null){ errors.rejectValue("startDate","startDate.required"); } if(officer.getEndDate() == null){ errors.rejectValue("endDate","endDate.required"); } logger.info("The Gender ID is " + officer.getGenderId().toString()); if(officer.getPhoneNo() == null){ errors.rejectValue("phoneNo", "phoneNo.required"); } } /** * @return the validateUserNameManager */ public ValidateUserNameManager getValidateUserNameManager() { return validateUserNameManager; } /** * @param validateUserNameManager the validateUserNameManager to set */ public void setValidateUserNameManager( ValidateUserNameManager validateUserNameManager) { this.validateUserNameManager = validateUserNameManager; } } Update Error Log using Logger.Error("Message", e): 39024 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 39025 [http-8084-2] ERROR com.crimetrack.service.OfficerRegistrationValidation - Message java.lang.NullPointerException at com.crimetrack.service.OfficerRegistrationValidation.validate(OfficerRegistrationValidation.java:47) at org.springframework.validation.DataBinder.validate(DataBinder.java:725) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:815) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:367) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - Error Occured When validating UserName

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  • Method chaining vs encapsulation

    - by Oak
    There is the classic OOP problem of method chaining vs "single-access-point" methods: main.getA().getB().getC().transmogrify(x, y) vs main.getA().transmogrifyMyC(x, y) The first seems to have the advantage that each class is only responsible for a smaller set of operations, and makes everything a lot more modular - adding a method to C doesn't require any effort in A, B or C to expose it. The downside, of course, is weaker encapsulation, which the second code solves. Now A has control of every method that passes through it, and can delegate it to its fields if it wants to. I realize there's no single solution and it of course depends on context, but I would really like to hear some input about other important differences between the two styles, and under what circumstances should I prefer either of them - because right now, when I try to design some code, I feel like I'm just not using the arguments to decide one way or the other.

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  • Are RSS feeds used? [closed]

    - by acidzombie24
    I was thinking about implementing RSS feeds on my site. The one thing that came to mind is Are RSS feeds ever used?! I don't use them nor know anyone who does. I know to use them it must be through an rss feed program or built in with the browser. I like my browser clean and i know many ppl dont know how to use/configure their browser. So with my thoughts i deducted that rss are not used 99.9999% of people (thats 4 decimal places which is really saying something). Now twitter on the other hand or even email may be used. But I have doubts about rss feeds. Can anyone give me statistics or change my mind on implementing it? I suspect it would be simple but i dont think i should bother if no one will ever use it. I dont even use SE/SO RSS feeds.

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  • How can I gather client's data on Google App Engine without using Datastore/Backend Instances too much?

    - by ruslan
    One of the projects I'm working on is online survey engine. It's my first big commercial project on Google App Engine. I need your advice on how to collect stats and efficiently record them in DataStore without bankrupting me. Initial requirements are: After user finishes survey client sends list of pairs [ID (int) + PercentHit (double)]. This list shows how close answers of this user match predefined answers of reference answerers (which identified by IDs). I call them "target IDs". Creator of the survey wants to see aggregated % for given IDs for last hour, particular timeframe or from the beginning of the survey. Some surveys may have thousands of target/reference answerers. So I created entity public class HitsStatsDO implements Serializable { @Id transient private Long id; transient private Long version = (long) 0; transient private Long startDate; @Parent transient private Key parent; // fake parent which contains target id @Transient int targetId; private double avgPercent; private long hitCount; } But writing HitsStatsDO for each target from each user would give a lot of data. For instance I had a survey with 3000 targets which was answered by ~4 million people within one week with 300K people taking survey in first day. Even if we assume they were answering it evenly for 24 hours it would give us ~1040 writes/second. Obviously it hits concurrent writes limit of Datastore. I decided I'll collect data for one hour and save that, that's why there are avgPercent and hitCount in HitsStatsDO. GAE instances are stateless so I had to use dynamic backend instance. There I have something like this: // Contains stats for one hour private class Shard { ReadWriteLock lock = new ReentrantReadWriteLock(); Map<Integer, HitsStatsDO> map = new HashMap<Integer, HitsStatsDO>(); // Key is target ID public void saveToDatastore(); public void updateStats(Long startDate, Map<Integer, Double> hits); } and map with shard for current hour and previous hour (which doesn't stay here for long) private HashMap<Long, Shard> shards = new HashMap<Long, Shard>(); // Key is HitsStatsDO.startDate So once per hour I dump Shard for previous hour to Datastore. Plus I have class LifetimeStats which keeps Map<Integer, HitsStatsDO> in memcached where map-key is target ID. Also in my backend shutdown hook method I dump stats for unfinished hour to Datastore. There is only one major issue here - I have only ONE backend instance :) It raises following questions on which I'd like to hear your opinion: Can I do this without using backend instance ? What if one instance is not enough ? How can I split data between multiple dynamic backend instances? It hard because I don't know how many I have because Google creates new one as load increases. I know I can launch exact number of resident backend instances. But how many ? 2, 5, 10 ? What if I have no load at all for a week. Constantly running 10 backend instances is too expensive. What do I do with data from clients while backend instance is dead/restarting?

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