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  • Query Object Pattern (Design Pattern)

    - by The Elite Gentleman
    Hi Guys, I need to implement a Query Object Pattern in Java for my customizable search interface (of a webapp I'm writing). Does anybody know where I can get an example/tutorial of Query Object Pattern (Martin Fowler's QoP)? Thanks in Advance ADDITION How to add a Query Pattern to an existing DAO pattern?

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  • Design by contract: predict methods needed, discipline yourself and deal with code that comes to min

    - by fireeyedboy
    I like the idea of designing by contract a lot (at least, as far as I understand the principal). I believe it means you define intefaces first before you start implementing actual code, right? However, from my limited experience (3 OOP years now) I usually can't resist the urge to start coding pretty early, for several reasons: because my limited experience has shown me I am unable to predict what methods I will be needing in the interface, so I might as well start coding right away. or because I am simply too impatient to write out the whole interfaces first. or when I do try it, I still wind up implementing bits of code already, because I fear I might forget this or that imporant bit of code, that springs to mind when I am designing the interfaces. As you see, especially with the last two points, this leads to a very disorderly way of doing thing. Tasks get mixed up. I should draw a clear line between designing interfaces and actual coding. If you, unlike me, are a good/disciplined planner, as intended above, how do you: ...know the majority of methods you will be needing up front so well? Especially if it's components that implement stuff you are not familiar with yet. ...keep yourself from resisting the urge to start coding right away? ...deal with code that comes to mind when you are designing the intefaces?

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  • Android: ListActivity design - changing the content of the List Adapter

    - by Rob
    Hi, I would like to write a rather simple content application which displays a list of textual items (along with a small pic). I have a standard menu in which each menu item represents a different category of textual items (news, sports, leisure etc.). Pressing a menu item will display a list of textual items of this category. Now, having a separate ListActivity for each category seems like an overkill (or does it?..) Naturally, it makes much more sense to use one ListActivity and replace the data of its adapter when each category is loaded. My concern is when "back" is pressed. The adapter is loaded with items of the current category and now I need to display list of the previous category (and enable clicking on list items too...). Since I have only one activity - I thought of backup and load mechanism in onPause() and onResume() functions as well as making some distinction whether these function are invoked as a result of a "new" event (menu item selected) or by a "back" press. This seems very cumbersome for such a trivial usage... Am I missing something here? Thanks, Rob

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  • a good book about software design

    - by Idan
    i'm looking for a book that talks about sofware decision like : when should i use thread pool and shouldn't. and in the first case, explains how. how should i acess my DB , how big my transactions should be how to read XML, to use DOM or SAX, what library to choose, and best ways to parse how to handle client-server app best efficient way and more stuff like that. is a book like that exist ? (preferably in c++ but not that important)

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  • Missing ideas in programming language design

    - by meyka
    I wanted to try something new and so I designed some programming languages and wrote interpreters for them: A rather low-level, not very expressive language. (I didn't want to parse complex expressions right at the beginning) It featured: Variables (yay) Subroutines, with a call stack Basic arithmetic functions, basic string manipulation, ... Code in the language looks like this: set i 0 inc i print i Very, very basic you see. A more high-level language I decided to make it structured and so it featured things like if-else, while, functions, and so on. The stuff most programming languages have. Ended up like a unworthy Python clone, I hated that. A code-golf language Which ended up similar to J, golfcode, APL, etc. Nothing special As you can see: I don't lack the skills but the ideas. I can't figure out anything new, not even bad, unneccessary things, for my languages. - Do you know of some weird things I could implement in my languages, which don't try to make programming harder (like most esoteric languages) but funnier or more different from other languages? It can't be possible that every weird thing has been tried out so far, or?

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  • How to sketch out an event-driven system?

    - by Jordan
    I'm trying to design a system in Node.js (an attempt at solving one of my earlier problems, using Node's concurrency) but I'm running into trouble figuring out how to draw a plan of how the thing should operate. I'm getting very tripped up thinking in terms of callbacks instead of returned values. The flow isn't linear, and it's really boggling my ability to draft it. How does one draw out an operational flow for an event-driven system? I need something I can look at and say "Ok, yes, that's how it will work. I'll start it over here, and it will give me back these results over here." Pictures would be very helpful for this one. Thanks. Edit: I'm looking for something more granular than UML, specifically, something that will help me transition from a blocking and object-oriented programming structure, where I'm comfortable, to a non-blocking and event driven structure, where I'm unfamiliar.

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  • good database design for localization

    - by rap-uvic
    Hi, I have 3 tables for localization: Locales, ResourceKeys, and Resources. Resources is a many to many table between ResourceKeys and Locales, and stores Resource values for each resource key in multiple languages. Now if I have a table called Event, which needs a localized title and description, how do I best do this? Do I create foreign key columns in Event table which point to ResourceKey IDs each for title and description, or is there a better way?

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  • Service Oriented Architecture & Domain-Driven Design

    - by Michael
    I've always developed code in a SOA type of way. This year I've been trying to do more DDD but I keep getting the feeling that I'm not getting it. At work our systems are load balanced and designed not to have state. The architecture is: Website ===Physical Layer== Main Service ==Physical Layer== Server 1/Service 2/Service 3/Service 4 Only Server 1,Service 2,Service 3 and Service 4 can talk to the database and the Main Service calls the correct service based on products ordered. Every physical layer is load balanced too. Now when I develop a new service, I try to think DDD in that service even though it doesn't really feel like it fits. I use good DDD principles like entities, value types, repositories, aggregates, factories and etc. I've even tried using ORM's but they just don't seem like they fit in a stateless architecture. I know there are ways around it, for example use IStatelessSession instead of ISession with NHibernate. However, ORM just feel like they don't fit in a stateless architecture. I've noticed I really only use some of the concepts and patterns DDD has taught me but the overall architecture is still SOA. I am starting to think DDD doesn't fit in large systems but I do think some of the patterns and concepts do fit in large systems. Like I said, maybe I'm just not grasping DDD or maybe I'm over analyzing my designs? Maybe by using the patterns and concepts DDD has taught me I am using DDD? Not sure if there is really a question to this post but more of thoughts I've had when trying to figure out where DDD fits in overall systems and how scalable it truly is. The truth is, I don't think I really even know what DDD is?

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  • ERD Design help meeded

    - by Mobi
    Hello guyz, I am new to ERD and stuff.Earlier i was drawing an erd that issued me some problems. the name of two entities in focus is "Bus" and "Passenger".What shall be the relationship between them. I think it should be many to many since one passenger can travel in many buses and a bus can give ride to many passengers.But one of my friend insisted that its a one-to-many relationship(A bus can have many passengers but a passenger can travel in only one bus).Plz let me know what's right. Also , whats the relationship between a class,students. Any help is appreciated.

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  • Database design: OR relation

    - by Ant
    I have a database with a "users" table containing data about my users. Each user is to be linked to a company or a college. I wish to have two separate tables "college" and "company" each with a field "ID". So how do I link each record in the users table to either a company or a college? The basic thing is that I wish to establish an "OR" relationship in the database.

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  • CSS::Website Design::GLASSES:: Colors for GLASSES website.

    - by Yosef
    Hi I doing Glasses(optica) store website. I thinking about colors that should be in glasses website. I think about colors that connected to glasses, like in other fields that i doing websites, but the problem is that glasses can be in different colors. I will be grateful for colors suggestions for glasses store and pretty glasses websites that already exist. Thanks, Yosef

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  • design business class for unit test

    - by Mauro Destro
    I'm trying to clean my code to make it unit-testable. I know that unit tests must be created while coding but... I have to do it now, with code completed. My business class is full of methods with a similar implementation like: var rep=new NHrepository<ModelClass1>(Session); rep.Where(x=>x.Field1==1).ToList(); first error (from my point of view) is that I don't have to use "new" but instead use DI and add in the ctor parameters a INHrepository modelClass1Repository. If in my class I have two or more repository of different model class? Each must be in the ctor? Or probably business class is not build with SeparationOfConcern principle?

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  • Need advice to design 'crack-proof' software

    - by alee
    I am currently working on a project where i need to create some architecture, framework or any standards by which i can "at least" increase the cracking method for a software, i.e, to add to software security. There are already different ways to activate a software which includes online activation, keys etc. I am currently studying few research papers as well. But there are still lot of things that i want to discuss. Could someone guide me to some decent forum, mailing list or something like that? or any other help would be appreciated.

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  • Java design: too many getters

    - by dege
    After writing a few lesser programs when learning Java the way I've designed the programs is with Model-View-Control. With using MVC I have a plethora of getter methods in the model for the view to use. It feels that while I gain on using MVC, for every new value added I have to add two new methods in the model which quickly get all cluttered with getter & setters. So I was thinking, maybe I should use the notifyObserver method that takes an argument. But wouldn't feel very smart to send every value by itself either so I figured, maybe if I send a kind of container with all the values, preferably only those that actually changed. What this would accomplish would be that instead of having a whole lot of getter methods I could just have one method in the model which put all relevant values in the container. Then in the view I would have a method called from the update which extracted the values from the container and assigning them to the correct fields. I have two questions concerning this. First: is this actually a viable way to do this. Would you recommend me doing something along these lines? Secondly: if I do use this plan and I don't want to keep sending fields that didn't actually change. How would I handle that without having to have if statements to check if the value is not null for every single value?

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  • relational database: how to design this table

    - by donpal
    I'm a database newbie designing a database. I'll use SO to ask my question because it's easier to ask it on something that you can see already, but it's not the same, it will just help me understand the right approach. As you can see, there are many questions here and each can have many answers. How should I store the answers in a table? Should I store all the answers in the SAME table with a unique id (make it the key) and just a new field for the question id? What if there are 100,000 answers like there is here? Do I still store them in 1 table? What keys should I use to minimize search time when I want to search for the answers of a specific question? The database is both read and write if that makes any difference in this case.

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  • database design to speed up hibernate querying of large dataset

    - by paddydub
    I currently have the below tables representing a bus network mapped in hibernate, accessed from a Spring MVC based bus route planner I'm trying to make my route planner application perform faster, I load all the above tables into Lists to perform the route planner logic. I would appreciate if anyone has any ideas of how to speed my performace Or any suggestions of another method to approach this problem of handling a large set of data Coordinate Connections Table (INT,INT,INT)( Containing 50,000 Coordinate Connections) ID, FROMCOORDID, TOCOORDID 1 1 2 2 1 17 3 1 63 4 1 64 5 1 65 6 1 95 Coordinate Table (INT,DECIMAL, DECIMAL) (Containing 4700 Coordinates) ID , LAT, LNG 0 59.352669 -7.264341 1 59.352669 -7.264341 2 59.350012 -7.260653 3 59.337585 -7.189798 4 59.339221 -7.193582 5 59.341408 -7.205888 Bus Stop Table (INT, INT, INT)(Containing 15000 Stops) StopID RouteID COORDINATEID 1000100001 100 17 1000100002 100 18 1000100003 100 19 1000100004 100 20 1000100005 100 21 1000100006 100 22 1000100007 100 23 This is how long it takes to load all the data from each table: stop.findAll = 148ms, stops.size: 15670 Hibernate: select coordinate0_.COORDINATEID as COORDINA1_2_, coordinate0_.LAT as LAT2_, coordinate0_.LNG as LNG2_ from COORDINATES coordinate0_ coord.findAll = 51ms , coordinates.size: 4704 Hibernate: select coordconne0_.COORDCONNECTIONID as COORDCON1_3_, coordconne0_.DISTANCE as DISTANCE3_, coordconne0_.FROMCOORDID as FROMCOOR3_3_, coordconne0_.TOCOORDID as TOCOORDID3_ from COORDCONNECTIONS coordconne0_ coordinateConnectionDao.findAll = 238ms ; coordConnectioninates.size:48132 Hibernate Annotations @Entity @Table(name = "STOPS") public class Stop implements Serializable { @Id @GeneratedValue @Column(name = "COORDINATEID") private Integer CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Table(name = "COORDINATES") public class Coordinate { @Id @GeneratedValue @Column(name = "COORDINATEID") private Integer CoordinateID; @Column(name = "LAT") private double latitude; @Column(name = "LNG") private double longitude; } @Entity @Table(name = "COORDCONNECTIONS") public class CoordConnection { @Id @GeneratedValue @Column(name = "COORDCONNECTIONID") private Integer CoordinateID; /** * From Coordinate_id value */ @Column(name = "FROMCOORDID", nullable = false) private int fromCoordID; /** * To Coordinate_id value */ @Column(name = "TOCOORDID", nullable = false) private int toCoordID; //private Coordinate toCoordID; }

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  • A good Design-by-Contract library for Java?

    - by Chris Jones
    A few years ago, I did a survey of DbC packages for Java, and I wasn't wholly satisfied with any of them. Unfortunately I didn't keep good notes on my findings, and I assume things have changed. Would anybody care to compare and contrast different DbC packages for Java?

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  • Good Domain Driven Design samples

    - by jlembke
    I'm learning about DDD and enjoying every minute of it. However, there are some practical issues that are confusing to me that I think seeing some good samples might clear up. So being at peace with those issues, does anyone know of some good working code samples that do a good job of modeling basic DDD concepts? Particularly interested in An illustrative Domain Model Repositories Use of Domain/Application Services Value Objects Aggregate Roots I know I'm probably asking for too much, but anything close will help.

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  • Database Design Primay Key, ID vs String

    - by LnDCobra
    Hi, I am currently planning to develop a music streaming application. And i am wondering what would be better as a primary key in my tables on the server. An ID int or a Unique String. Methods 1: Songs Table: SongID(int), Title(string), Artist*(string), Length(int), Album*(string) Genre Table Genre(string), Name(string) SongGenre: SongID*(int), Genre*(string) Method 2 Songs Table: SongID(int), Title(string), ArtistID*(int), Length(int), AlbumID*(int) Genre Table GenreID(int), Name(string) SongGenre: SongID*(int), GenreID*(int) Key: Bold = Primary Key, Field* = Foreign Key I'm currently designing using method 2 as I believe it will speed up lookup performance and use less space as an int takes a lot less space then a string. Is there any reason this isn't a good idea? Is there anything I should be aware of?

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  • Database design grouping contacts by lists and companies

    - by Serge
    Hi, I'm wondering what would be the best way to group contacts by their company. Right now a user can group their contacts by custom created lists but I'd like to be able to group contacts by their company as well as store the contact's position (i.e. Project Manager of XYZ company). Database wise this is what I have for grouping contacts into lists contact [id_contact] [int] PK NOT NULL, [lastName] [varchar] (128) NULL, [firstName] [varchar] (128) NULL, ...... contact_list [id_contact] [int] FK, [id_list] [int] FK, list [id_list] [int] PK [id_user] [int] FK [list_name] [varchar] (128) NOT NULL, [description] [TEXT] NULL Should I implement something similar for grouping contacts by company? If so how would I store the contact's position in that company and how can I prevent data corruption if a user modifies a contact's company name. For instance John Doe changed companies but the other co-workers are still in the old company. I doubt that will happen often (might not even happen at all) but better be safe than sorry. I'm also keeping an audit trail so in a way the contact would still need to be linked to the old company as well as the new one but without confusing what company he's actually working at the moment. I hope that made sense... Has anyone encountered such a problem? UPDATE Would something like this make sense contact_company [id_contact_company] [int] PK [id_contact] [int] FK [id_company] [int] FK [contact_title] [varchar] (128) company [id_company] [int] PK NOT NULL, [company_name] [varchar] (128) NULL, [company_description] [varchar] (300) NULL, [created_date] [datetime] NOT NULL This way a contact can work for more than one company and contacts can be grouped by companies

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  • Learning OOP Design

    - by waiwai933
    I've read Head First Java, and I understand how OOP works. Here's my problem: I'm a PHP programmer, and while I've used OOP in PHP, I'm having trouble figuring out what should be an object and what methods to give it. For example, let's say I have a app that allows people to log in and edit a document. Why should the document be an object if there will ever only be one instance? Should I give the deleteDocument() method to the document object or the admin object? The document is the one being deleted, but the admin is the one performing the action. So my real question is, coming from a procedural background, how do I figure out what should be objects and what should have what methods?

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