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  • how to design a schema where the columns of a table are not fixed

    - by hIpPy
    I am trying to design a schema where the columns of a table are not fixed. Ex: I have an Employee table where the columns of the table are not fixed and vary (attributes of Employee are not fixed and vary). Nullable columns in the Employee table itself i.e. no normalization Instead of adding nullable columns, separate those columns out in their individual tables ex: if Address is a column to be added then create table Address[EmployeeId, AddressValue]. Create tables ExtensionColumnName [EmployeeId, ColumnName] and ExtensionColumnValue [EmployeeId, ColumnValue]. ExtensionColumnName would have ColumnName as "Address" and ExtensionColumnValue would have ColumnValue as address value. Employee table EmployeeId Name ExtensionColumnName table ColumnNameId EmployeeId ColumnName ExtensionColumnValue table EmployeeId ColumnNameId ColumnValue There is a drawback is the first two ways as the schema changes with every new attribute. Note that adding a new attribute is frequent. I am not sure if this is the good or bad design. If someone had a similar decision to make, please give an insight on things like foreign keys / data integrity, indexing, performance, reporting etc.

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  • Node & Redis: Crucial Design Issues in Production Mode

    - by Ali
    This question is a hybrid one, being both technical and system design related. I'm developing the backend of an application that will handle approx. 4K request per second. We are using Node.js being super fast and in terms of our database struction we are using MongoDB, with Redis being a layer between Node and MongoDB handling volatile operations. I'm quite stressed because we are expecting concurrent requests that we need to handle carefully and we are quite close to launch. However I do not believe I've applied the correct approach on redis. I have a class Student, and they constantly change stages(such as 'active', 'doing homework','in lesson' etc. Thus I created a Redis DB for each state. (1 for being 'active', 2 for being 'doing homework'). Above I have the structure of the 'active' students table; xa5p - JSON stringified object #1 pQrW - JSON stringified object #2 active_student_table - {{studentId:'xa5p'}, {studentId:'pQrW'}} Since there is no 'select all keys method' in Redis, I've been suggested to use a set such that when I run command 'smembers' I receive the keys and later on do 'get' for each id in order to find a specific user (lets say that age older than 15). I've been also suggested that in fact I used never use keys in production mode. My question is, no matter how 'conceptual' it is, what specific things I should avoid doing in Node & Redis in production stage?. Are they any issues related to my design? Students must be objects and I sure can list them in a list but I haven't done yet. Is it that crucial in production stage?

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  • Are Tuples a poor design decision in C#?

    - by Jason Webb
    With the addition of the Tuple class in .net 4, I have been trying to decide if using them in my design is a bad choice or not. The way I see it, a Tuple is a shortcut to writing a result class (I am sure there are other uses too). So this: public class ResultType { public string StringValue { get; set; } public int IntValue { get; set; } } public ResultType GetAClassedValue() { //..Do Some Stuff ResultType result = new ResultType { StringValue = "A String", IntValue = 2 }; return result; } Is equivalent to this: public Tuple<string, int> GetATupledValue() { //...Do Some stuff Tuple<string, int> result = new Tuple<string, int>("A String", 2); return result; } So setting aside the possibility that I am missing the point of Tuples, is the example with a Tuple a bad design choice? To me it seems like less clutter, but not as self documenting and clean. Meaning that with the type ResultType, it is very clear later on what each part of the class means but you have extra code to maintain. With the Tuple<string, int> you will need to look up and figure out what each Item represents, but you write and maintain less code. Any experience you have had with this choice would be greatly appreciated.

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  • design pattern for related inputs

    - by curiousMo
    My question is a design question : let's say i have a data entry web page with 4 drop down lists, each depending on the previous one, and a bunch of text boxes. ddlCountry (DropDownList) ddlState (DropDownList) ddlCity (DropDownList) ddlBoro (DropDownList) txtAddress (TxtBox) txtZipcode(TxtBox) and an object that represents a datarow with a value for each: countrySeqid stateSeqid citySeqid boroSeqid address zipCode naturally the country, state, city and boro values will be values of primary keys of some lookup tables. when the user chooses to edits that record, i would load it from database and load it into the page. the issue that I have is how to streamline loading the DropDownLists. i have some code that would grab the object,look thru its values and move them to their corresponding input controls in one shot. but in this case i will have to load the ddlCountry with possible values, then assign values, then do the same thing for the rest of the ddls. I guess i am looking for an elegant solution. i am using asp.net, but i think it is irrelevant to the question. i am looking more into a design pattern.

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  • Compromising design & code quality to integrate with existing modules

    - by filip-fku
    Greetings! I inherited a C#.NET application I have been extending and improving for a while now. Overall it was obviously a rush-job (or whoever wrote it was seemingly less competent than myself). The app pulls some data from an embedded device & displays and manipulates it. At the core is a communications thread in the main application form which executes a 600+ lines of code method which calls functions all over the place, implementing a state machine - lots of if-state-then-do type code. Interaction with the device is done by setting the state/mode globally and letting the thread do it's thing. (This is just one example of the badness of the code - overall it is not very OO-like, it reminds of the style of embedded C code the device firmware is written in). My problem is that this piece of code is central to the application. The software, communications protocol or device firmware are not documented at all. Obviously to carry on with my work I have to interact with this code. What I would like some guidance on, is whether it is worth scrapping this code & trying to piece together something more reasonable from the information I can reverse engineer? I can't decide! The reason I don't want to refactor is because the code already works, and changing it will surely be a long, laborious and unpleasant task. On the flip side, not refactoring means I have to sometimes compromise the design of other modules so that I may call my code from this state machine! I've heard of "If it ain't broke don't fix it!", so I am wondering if it should apply when "it" is influencing the design of future code! Any advice would be appreciated! Thanks!

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  • Importing data from third party datasource (open architecture design )

    - by mare
    How would you design an application (classes, interfaces in class library) in .NET when we have a fixed database design on our side and we need to support imports of data from third party data sources, which will most likely be in XML? For instance, let us say we have a Products table in our DB which has columns Id Title Description TaxLevel Price and on the other side we have for instance Products: ProductId ProdTitle Text BasicPrice Quantity. Currently I do it like this: Have the third party XML convert to classes and XSD's and then deserialize its contents into strong typed objects (what we get as a result of this process is classes like ThirdPartyProduct, ThirdPartyClassification, etc.). Then I have methods like this: InsertProduct(ThirdPartyProduct newproduct) I do not use interfaces at the moment but I would like them to. What I would like is implement something like public class Contoso_ProductSynchronization : ProductSynchronization InsertProduct(ContosoProduct p) where ProductSynchronization will be an interface or abstract class. There will most likely be many implementations of ProductSynchronization. I cannot hardcode the types - classes like ContosoProduct, NorthwindProduct might be created from the third party XML's (so preferably I would continue to use deserialization). Hopefully someone will understand what I'm trying to explain here. Just imagine you are the seller and you have numerous providers and each one uses their own proprietary XML format. I don't mind the development, which will of course be needed everytime new format appears, because it will only require 10-20 methods to be implemented, I just want the architecture to be open and support that.

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  • Why make JavaScript class based?

    - by Carnotaurus
    JavaScript is a prototype language. To turn it into a class based language adds little value? I am not talking about best-practice here. I remember reading an article from way back, which claimed that the class-based worldview is perceivably more flawed than the one of prototypes. My summary can be found here: http://carnotaurus.tumblr.com/post/3248631891/class-based-javascript-or-not. I am resisting to use the class-based jQuery add-on and other attempts at faciliating class-based JavaScript. Peer pressure is strong but is there a stronger theoretical or practical reason why I stop resisting?

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  • How to make this design closer to proper DDD?

    - by Seralize
    I've read about DDD for days now and need help with this sample design. All the rules of DDD make me very confused to how I'm supposed to build anything at all when domain objects are not allowed to show methods to the application layer; where else to orchestrate behaviour? Repositories are not allowed to be injected into entities and entities themselves must thus work on state. Then an entity needs to know something else from the domain, but other entity objects are not allowed to be injected either? Some of these things makes sense to me but some don't. I've yet to find good examples of how to build a whole feature as every example is about Orders and Products, repeating the other examples over and over. I learn best by reading examples and have tried to build a feature using the information I've gained about DDD this far. I need your help to point out what I do wrong and how to fix it, most preferably with code as "I would not recomment doing X and Y" is very hard to understand in a context where everything is just vaguely defined already. If I can't inject an entity into another it would be easier to see how to do it properly. In my example there are users and moderators. A moderator can ban users, but with a business rule: only 3 per day. I did an attempt at setting up a class diagram to show the relationships (code below): interface iUser { public function getUserId(); public function getUsername(); } class User implements iUser { protected $_id; protected $_username; public function __construct(UserId $user_id, Username $username) { $this->_id = $user_id; $this->_username = $username; } public function getUserId() { return $this->_id; } public function getUsername() { return $this->_username; } } class Moderator extends User { protected $_ban_count; protected $_last_ban_date; public function __construct(UserBanCount $ban_count, SimpleDate $last_ban_date) { $this->_ban_count = $ban_count; $this->_last_ban_date = $last_ban_date; } public function banUser(iUser &$user, iBannedUser &$banned_user) { if (! $this->_isAllowedToBan()) { throw new DomainException('You are not allowed to ban more users today.'); } if (date('d.m.Y') != $this->_last_ban_date->getValue()) { $this->_ban_count = 0; } $this->_ban_count++; $date_banned = date('d.m.Y'); $expiration_date = date('d.m.Y', strtotime('+1 week')); $banned_user->add($user->getUserId(), new SimpleDate($date_banned), new SimpleDate($expiration_date)); } protected function _isAllowedToBan() { if ($this->_ban_count >= 3 AND date('d.m.Y') == $this->_last_ban_date->getValue()) { return false; } return true; } } interface iBannedUser { public function add(UserId $user_id, SimpleDate $date_banned, SimpleDate $expiration_date); public function remove(); } class BannedUser implements iBannedUser { protected $_user_id; protected $_date_banned; protected $_expiration_date; public function __construct(UserId $user_id, SimpleDate $date_banned, SimpleDate $expiration_date) { $this->_user_id = $user_id; $this->_date_banned = $date_banned; $this->_expiration_date = $expiration_date; } public function add(UserId $user_id, SimpleDate $date_banned, SimpleDate $expiration_date) { $this->_user_id = $user_id; $this->_date_banned = $date_banned; $this->_expiration_date = $expiration_date; } public function remove() { $this->_user_id = ''; $this->_date_banned = ''; $this->_expiration_date = ''; } } // Gathers objects $user_repo = new UserRepository(); $evil_user = $user_repo->findById(123); $moderator_repo = new ModeratorRepository(); $moderator = $moderator_repo->findById(1337); $banned_user_factory = new BannedUserFactory(); $banned_user = $banned_user_factory->build(); // Performs ban $moderator->banUser($evil_user, $banned_user); // Saves objects to database $user_repo->store($evil_user); $moderator_repo->store($moderator); $banned_user_repo = new BannedUserRepository(); $banned_user_repo->store($banned_user); Should the User entitity have a 'is_banned' field which can be checked with $user->isBanned();? How to remove a ban? I have no idea.

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  • Help with Design for Vacation Tracking System (C#/.NET/Access/WebServices/SOA/Excel) [closed]

    - by Aaronaught
    I have been tasked with developing a system for tracking our company's paid time-off (vacation, sick days, etc.) At the moment we are using an Excel spreadsheet on a shared network drive, and it works pretty well, but we are concerned that we won't be able to "trust" employees forever and sometimes we run into locking issues when two people try to open the spreadsheet at once. So we are trying to build something a little more robust. I would like some input on this design in terms of maintainability, scalability, extensibility, etc. It's a pretty simple workflow we need to represent right now: I started with a basic MS Access schema like this: Employees (EmpID int, EmpName varchar(50), AllowedDays int) Vacations (VacationID int, EmpID int, BeginDate datetime, EndDate datetime) But we don't want to spend a lot of time building a schema and database like this and have to change it later, so I think I am going to go with something that will be easier to expand through configuration. Right now the vacation table has this schema: Vacations (VacationID int, PropName varchar(50), PropValue varchar(50)) And the table will be populated with data like this: VacationID | PropName | PropValue -----------+--------------+------------------ 1 | EmpID | 4 1 | EmpName | James Jones 1 | Reason | Vacation 1 | BeginDate | 2/24/2010 1 | EndDate | 2/30/2010 1 | Destination | Spectate Swamp 2 | ... | ... I think this is a pretty good, extensible design, we can easily add new properties to the vacation like the destination or maybe approval status, etc. I wasn't too sure how to go about managing the database of valid properties, I thought of putting them in a separate PropNames table but it gets complicated to manage all the different data types and people say that you shouldn't put CLR type names into a SQL database, so I decided to use XML instead, here is the schema: <VacationProperties> <PropertyNames>EmpID,EmpName,Reason,BeginDate,EndDate,Destination</PropertyNames> <PropertyTypes>System.Int32,System.String,System.String,System.DateTime,System.DateTime,System.String</PropertyTypes> <PropertiesRequired>true,true,false,true,true,false</PropertiesRequired> </VacationProperties> I might need more fields than that, I'm not completely sure. I'm parsing the XML like this (would like some feedback on the parsing code): string xml = File.ReadAllText("properties.xml"); Match m = Regex.Match(xml, "<(PropertyNames)>(.*?)</PropertyNames>"; string[] pn = m.Value.Split(','); // do the same for PropertyTypes, PropertiesRequired Then I use the following code to persist configuration changes to the database: string sql = "DROP TABLE VacationProperties"; sql = sql + " CREATE TABLE VacationProperties "; sql = sql + "(PropertyName varchar(100), PropertyType varchar(100) "; sql = sql + "IsRequired varchar(100))"; for (int i = 0; i < pn.Length; i++) { sql = sql + " INSERT VacationProperties VALUES (" + pn[i] + "," + pt[i] + "," + pv[i] + ")"; } // GlobalConnection is a singleton new SqlCommand(sql, GlobalConnection.Instance).ExecuteReader(); So far so good, but after a few days of this I then realized that a lot of this was just a more specific kind of a generic workflow which could be further abstracted, and instead of writing all of this boilerplate plumbing code I could just come up with a workflow and plug it into a workflow engine like Windows Workflow Foundation and have the users configure it: In order to support routing these configurations throw the workflow system, it seemed natural to implement generic XML Web Services for this instead of just using an XML file as above. I've used this code to implement the Web Services: public class VacationConfigurationService : WebService { [WebMethod] public void UpdateConfiguration(string xml) { // Above code goes here } } Which was pretty easy, although I'm still working on a way to validate that XML against some kind of schema as there's no error-checking yet. I also created a few different services for other operations like VacationSubmissionService, VacationReportService, VacationDataService, VacationAuthenticationService, etc. The whole Service Oriented Architecture looks like this: And because the workflow itself might change, I have been working on a way to integrate the WF workflow system with MS Visio, which everybody at the office already knows how to use so they could make changes pretty easily. We have a diagram that looks like the following (it's kind of hard to read but the main items are Activities, Authenticators, Validators, Transformers, Processors, and Data Connections, they're all analogous to the services in the SOA diagram above). The requirements for this system are: (Note - I don't control these, they were given to me by management) Main workflow must interface with Excel spreadsheet, probably through VBA macros (to ease the transition to the new system) Alerts should integrate with MS Outlook, Lotus Notes, and SMS (text messages). We also want to interface it with the company Voice Mail system but that is not a "hard" requirement. Performance requirements: Must handle 250,000 Transactions Per Second Should be able to handle up to 20,000 employees (right now we have 3) 99.99% uptime ("four nines") expected Must be secure against outside hacking, but users cannot be required to enter a username/password. Platforms: Must support Windows XP/Vista/7, Linux, iPhone, Blackberry, DOS 2.0, VAX, IRIX, PDP-11, Apple IIc. Time to complete: 6 to 8 weeks. My questions are: Is this a good design for the system so far? Am I using all of the recommended best practices for these technologies? How do I integrate the Visio diagram above with the Windows Workflow Foundation to call the ConfigurationService and persist workflow changes? Am I missing any important components? Will this be extensible enough to support any scenario via end-user configuration? Will the system scale to the above performance requirements? Will we need any expensive hardware to run it? Are there any "gotchas" I should know about with respect to cross-platform compatibility? For example would it be difficult to convert this to an iPhone app? How long would you expect this to take? (We've dedicated 1 week for testing so I'm thinking maybe 5 weeks?) Many thanks for your advices, Aaron

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  • Design for Vacation Tracking System

    - by Aaronaught
    I have been tasked with developing a system for tracking our company's paid time-off (vacation, sick days, etc.) At the moment we are using an Excel spreadsheet on a shared network drive, and it works pretty well, but we are concerned that we won't be able to "trust" employees forever and sometimes we run into locking issues when two people try to open the spreadsheet at once. So we are trying to build something a little more robust. I would like some input on this design in terms of maintainability, scalability, extensibility, etc. It's a pretty simple workflow we need to represent right now: I started with a basic MS Access schema like this: Employees (EmpID int, EmpName varchar(50), AllowedDays int) Vacations (VacationID int, EmpID int, BeginDate datetime, EndDate datetime) But we don't want to spend a lot of time building a schema and database like this and have to change it later, so I think I am going to go with something that will be easier to expand through configuration. Right now the vacation table has this schema: Vacations (VacationID int, PropName varchar(50), PropValue varchar(50)) And the table will be populated with data like this: VacationID | PropName | PropValue -----------+--------------+------------------ 1 | EmpID | 4 1 | EmpName | James Jones 1 | Reason | Vacation 1 | BeginDate | 2/24/2010 1 | EndDate | 2/30/2010 1 | Destination | Spectate Swamp 2 | ... | ... I think this is a pretty good, extensible design, we can easily add new properties to the vacation like the destination or maybe approval status, etc. I wasn't too sure how to go about managing the database of valid properties, I thought of putting them in a separate PropNames table but it gets complicated to manage all the different data types and people say that you shouldn't put CLR type names into a SQL database, so I decided to use XML instead, here is the schema: <VacationProperties> <PropertyNames>EmpID,EmpName,Reason,BeginDate,EndDate,Destination</PropertyNames> <PropertyTypes>System.Int32,System.String,System.String,System.DateTime,System.DateTime,System.String</PropertyTypes> <PropertiesRequired>true,true,false,true,true,false</PropertiesRequired> </VacationProperties> I might need more fields than that, I'm not completely sure. I'm parsing the XML like this (would like some feedback on the parsing code): string xml = File.ReadAllText("properties.xml"); Match m = Regex.Match(xml, "<(PropertyNames)>(.*?)</PropertyNames>"; string[] pn = m.Value.Split(','); // do the same for PropertyTypes, PropertiesRequired Then I use the following code to persist configuration changes to the database: string sql = "DROP TABLE VacationProperties"; sql = sql + " CREATE TABLE VacationProperties "; sql = sql + "(PropertyName varchar(100), PropertyType varchar(100) "; sql = sql + "IsRequired varchar(100))"; for (int i = 0; i < pn.Length; i++) { sql = sql + " INSERT VacationProperties VALUES (" + pn[i] + "," + pt[i] + "," + pv[i] + ")"; } // GlobalConnection is a singleton new SqlCommand(sql, GlobalConnection.Instance).ExecuteReader(); So far so good, but after a few days of this I then realized that a lot of this was just a more specific kind of a generic workflow which could be further abstracted, and instead of writing all of this boilerplate plumbing code I could just come up with a workflow and plug it into a workflow engine like Windows Workflow Foundation and have the users configure it: In order to support routing these configurations throw the workflow system, it seemed natural to implement generic XML Web Services for this instead of just using an XML file as above. I've used this code to implement the Web Services: public class VacationConfigurationService : WebService { [WebMethod] public void UpdateConfiguration(string xml) { // Above code goes here } } Which was pretty easy, although I'm still working on a way to validate that XML against some kind of schema as there's no error-checking yet. I also created a few different services for other operations like VacationSubmissionService, VacationReportService, VacationDataService, VacationAuthenticationService, etc. The whole Service Oriented Architecture looks like this: And because the workflow itself might change, I have been working on a way to integrate the WF workflow system with MS Visio, which everybody at the office already knows how to use so they could make changes pretty easily. We have a diagram that looks like the following (it's kind of hard to read but the main items are Activities, Authenticators, Validators, Transformers, Processors, and Data Connections, they're all analogous to the services in the SOA diagram above). The requirements for this system are: (Note - I don't control these, they were given to me by management) Main workflow must interface with Excel spreadsheet, probably through VBA macros (to ease the transition to the new system) Alerts should integrate with MS Outlook, Lotus Notes, and SMS (text messages). We also want to interface it with the company Voice Mail system but that is not a "hard" requirement. Performance requirements: Must handle 250,000 Transactions Per Second Should be able to handle up to 20,000 employees (right now we have 3) 99.99% uptime ("four nines") expected Must be secure against outside hacking, but users cannot be required to enter a username/password. Platforms: Must support Windows XP/Vista/7, Linux, iPhone, Blackberry, DOS 2.0, VAX, IRIX, PDP-11, Apple IIc. Time to complete: 6 to 8 weeks. My questions are: Is this a good design for the system so far? Am I using all of the recommended best practices for these technologies? How do I integrate the Visio diagram above with the Windows Workflow Foundation to call the ConfigurationService and persist workflow changes? Am I missing any important components? Will this be extensible enough to support any scenario via end-user configuration? Will the system scale to the above performance requirements? Will we need any expensive hardware to run it? Are there any "gotchas" I should know about with respect to cross-platform compatibility? For example would it be difficult to convert this to an iPhone app? How long would you expect this to take? (We've dedicated 1 week for testing so I'm thinking maybe 5 weeks?)

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  • Observer pattern and violation of Single Principality Rule

    - by Devil Jin
    I have an applet which repaints itself once the text has changed Design 1: //MyApplet.java public class MyApplet extends Applet implements Listener{ private DynamicText text = null; public void init(){ text = new DynamicText("Welcome"); } public void paint(Graphics g){ g.drawString(text.getText(), 50, 30); } //implement Listener update() method public void update(){ repaint(); } } //DynamicText.java public class DynamicText implements Publisher{ // implements Publisher interface methods //notify listeners whenever text changes } Isn't this a violation of Single Responsibility Principle where my Applet not only acts as Applet but also has to do Listener job. Same way DynamicText class not only generates the dynamic text but updates the registered listeners. Design 2: //MyApplet.java public class MyApplet extends Applet{ private AppletListener appLstnr = null; public void init(){ appLstnr = new AppletListener(this); // applet stuff } } // AppletListener.java public class AppletListener implements Listener{ private Applet applet = null; public AppletListener(Applet applet){ this.applet = applet; } public void update(){ this.applet.repaint(); } } // DynamicText public class DynamicText{ private TextPublisher textPblshr = null; public DynamicText(TextPublisher txtPblshr){ this.textPblshr = txtPblshr; } // call textPblshr.notifyListeners whenever text changes } public class TextPublisher implments Publisher{ // implements publisher interface methods } Q1. Is design 1 a SPR violation? Q2. Is composition a better choice here to remove SPR violation as in design 2.

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  • Which book should I choose?

    - by sebastianlarsson
    Hi guys, I'm looking for a good read on object oriented design. The two books I'm currently looking Head First Design Patterns and Head First Object object-oriented analysis & design. They seem very similar when looking at the contents and browsing through available sample text. Which one would be the best choice? About myself: I have a bachelor in computer science and I am currently studying Msc. Software Quality Engineering (read Software Engineering with focus on Quality). I am already confident in object-oriented design and have a lot of programming courses in my backpack. I have done games in c++, courses in advanced java programming (I am SCJP certified), but my preferred language is C#. I have also worked with Java for the last 7 months while studying. I am currently also studying for certificates in C# (apart from my usual studies). So I believe I have the prerequisites of actually understanding the contents of both books. Reason: I just want to be better and keep evolving as a programmer. I think it is fun. I believe Bert Bates and Kathy Sierra are involved in both these books and I have previously read their SCJP preparation book in java. I really do enjoy their style of writing. Other books which I am considering are: Clean Code: A Handbook Of Agile Software Craftsmanship Thx in advance Sebastian

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  • Observer pattern and violation of Single Responsibility Principle

    - by Devil Jin
    I have an applet which repaints itself once the text has changed Design 1: //MyApplet.java public class MyApplet extends Applet implements Listener{ private DynamicText text = null; public void init(){ text = new DynamicText("Welcome"); } public void paint(Graphics g){ g.drawString(text.getText(), 50, 30); } //implement Listener update() method public void update(){ repaint(); } } //DynamicText.java public class DynamicText implements Publisher{ // implements Publisher interface methods //notify listeners whenever text changes } Isn't this a violation of Single Responsibility Principle where my Applet not only acts as Applet but also has to do Listener job. Same way DynamicText class not only generates the dynamic text but updates the registered listeners. Design 2: //MyApplet.java public class MyApplet extends Applet{ private AppletListener appLstnr = null; public void init(){ appLstnr = new AppletListener(this); // applet stuff } } // AppletListener.java public class AppletListener implements Listener{ private Applet applet = null; public AppletListener(Applet applet){ this.applet = applet; } public void update(){ this.applet.repaint(); } } // DynamicText public class DynamicText{ private TextPublisher textPblshr = null; public DynamicText(TextPublisher txtPblshr){ this.textPblshr = txtPblshr; } // call textPblshr.notifyListeners whenever text changes } public class TextPublisher implments Publisher{ // implements publisher interface methods } Q1. Is design 1 a SPR violation? Q2. Is composition a better choice here to remove SPR violation as in design 2.

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  • Session Update from IASA 2010

    - by [email protected]
    Below: Tom Kristensen, senior vice president at Marsh US Consumer, and Roger Soppe, CLU, LUTCF, senior director of insurance strategy, Oracle Insurance. Tom and Roger participated in a panel discussion on policy administration systems this week at IASA 2010. This week was the 82nd Annual IASA Educational Conference & Business Show held in Grapevine, Texas. While attending the conference, I had the pleasure of serving as a panelist in one of many of the outstanding sessions conducted this year. The session - entitled "Achieving Business Agility and Promoting Growth with a Modern Policy Administration System" - included industry experts Steve Forte from OneShield, Mike Sciole of IFG Companies, and Tom Kristensen, senior vice president at Marsh US Consumer. The session was conducted as a panel discussion and focused on how insurers can leverage best practices to mitigate risk while enabling rapid product innovation through a modern policy administration system. The panelists offered insight into business and technical challenges for both Life & Annuity and Property & Casualty carriers. The session had three primary learning objectives: Identifying how replacing a legacy system with a more modern policy administration solution can deliver agility and growth Identifying how processes and system should be re-engineered or replaced in order to improve speed-to-market and product support Uncovering how to leverage best practices to mitigate risk during a migration to a new platform Tom Kristensen, who is an industry veteran with over 20 years of experience, was able was able to offer a unique perspective as a business process outsourcer (BPO). Marsh US Consumer is currently implementing both the Oracle Insurance Policy Administration solution and the Oracle Revenue Management and Billing platform while at the same time implementing a new BPO customer. Tom offered insight on the need to replace their aging systems and Marsh's ability to drive new products and processes with a modern solution. As a best practice, their current project has empowered their business users to play a major role in both the requirements gathering and configuration phases. Tom stated that working with a modern solution has also enabled his organization to use a more agile implementation methodology and get hands-on experience with the software earlier in the project. He also indicated that Marsh was encouraged by how quickly it will be able to implement new products, which is another major advantage of a modern rules-based system. One of the more interesting issues was raised by an audience member who asked, "With all the vendor solutions available in North American and across Europe, what is going to make some of them more successful than others and help ensure their long term success?" Panelist Mike Sciole, IFG Companies suggested that carriers do their due diligence and follow a structured evaluation process focusing on vendors who demonstrate they have the "cash to invest in long term R&D" and evaluate audited annual statements for verification. Other panelists suggested that the vendor space will continue to evolve and those with a strong strategy focused on the insurance industry and a solid roadmap will likely separate themselves from the rest. The session concluded with the panelists offering advice about not being afraid to evaluate new modern systems. While migrating to a new platform can be challenging and is typically only undertaken every 15+ years by carriers, the ability to rapidly deploy and manage new products, create consistent processes to better service customers, and the ability to manage their business more effectively, transparently and securely are well worth the effort. Roger A.Soppe, CLU, LUTCF, is the Senior Director of Insurance Strategy, Oracle Insurance.

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  • AJAX Web Application Design

    - by Colonel Sponsz
    I'm working on a personal project to build a small web app that is built using AJAX requests and talks to a RESTful API rather than traditional HTML pages and form submissions. Are there any online articles or tutorials or any books that people could recommend that cover design patterns for this kind of thing?

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  • Embedding a flowchart design surface in a .NET application

    - by PaulB
    I need to incorporate a flowchart design surface into an application we're developing to allow users to create what are essentially workflows/schedules. I need to be able to create my own 'shapes', set custom properties on them and possibly have a bit of logic in there too (if, while etc). I know I need to take a look at hosting WF in the application. It looks like a good fit, but what other designer compoments out there could I use?

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  • Database Design sugessition

    - by Manoj kumar
    I am in the plan of building a information service website similar to http://us.justdial.com/, I was in the confusion of designing the database. The datas stored in the database are List of categories Name of the company and its address, phone number, category, etc... (i am going to use MYSQL Database) how could i design the database that makes the accessing of those data easier ? Thanks in advance

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  • programming logic and design pleas friends i need a flowcharts or pseudocode

    - by alex
    ***the midvile park maintains records containing info about players on it's soccer teams . each record contain a players first name,last name,and team number . the team are team number team name 1 goal getters 2 the force 3 top gun 4 shooting stars 5 midfield monsters design a proggram that accept player data and creates a report that lists each** player a long with his or her team number and team name**

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  • Removing Design Outlining

    - by Kevin
    Is there a way to remove the outlining in Visual Studio in the design page of a form? If it is possible, it would save me some time so that I would not have to keep compiling and running the program every time I wanted to see if I put my form together correctly without any caps between images, etc. For example, something like this. I want to remove the lines that surround each image (yes, those are separate images put together).

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  • Getters and Setters are bad OO design?

    - by Dan
    Getters and Setters are bad Briefly reading over the above article I find that getters and setters are bad OO design and should be avoided as they go against Encapsulation and Data Hiding. As this is the case how can it be avoided when creating objects and how can one model objects to take this into account. In cases where a getter or setter is required what other alternatives can be used? Thanks.

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  • Good event calendaring / scheduling design guide?

    - by Neil McF
    Hello, In an application I'm designing, the user has to be able to specify rather complex event scheduling (continuous time-block vs. daily time-blocks, exception date/times, recurrence patterns etc.) Does anyone know of a good design page for such a thing online? For example, I was highly impressed with this page's description of how to do database audit trails, and would love something similar. Thanks.

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  • Finite State Machine : Bad design?

    - by f4
    Are Finite State Machines generally considered as bad design in OOP ? I hear that a lot. And, after I had to work on a really old, undocumented piece of C++ making use of it, I tend to agree. It was a pain to debug. what about readability/maintainability concerns?

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  • Database Design Question regaurding duplicate information.

    - by galford13x
    I have a database that contains a history of product sales. For example the following table CREATE TABLE SalesHistoryTable ( OrderID, // Order Number Unique to all orders ProductID, // Product ID can be used as a Key to look up product info in another table Price, // Price of the product per unit at the time of the order Quantity, // quantity of the product for the order Total, // total cost of the order for the product. (Price * Quantity) Date, // Date of the order StoreID, // The store that created the Order PRIMARY KEY(OrderID)); The table will eventually have millions of transactions. From this, profiles can be created for products in different geographical regions (based on the StoreID). Creating these profiles can be very time consuming as a database query. For example. SELECT ProductID, StoreID, SUM(Total) AS Total, SUM(Quantity) QTY, SUM(Total)/SUM(Quantity) AS AvgPrice FROM SalesHistoryTable GROUP BY ProductID, StoreID; The above query could be used to get the Information based on products for any particular store. You could then determine which store has sold the most, has made the most money, and on average sells for the most/least. This would be very costly to use as a normal query run anytime. What are some design descisions in order to allow these types of queries to run faster assuming storage size isn’t an issue. For example, I could create another Table with duplicate information. Store ID (Key), Product ID, TotalCost, QTY, AvgPrice And provide a trigger so that when a new order is received, the entry for that store is updated in a new table. The cost for the update is almost nothing. What should be considered when given the above scenario?

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  • Flexible design - customizable entity model, UI and workflow

    - by Ngm
    Hi All, I want to achieve the following aspects in the software I am building: 1. Customizable entity model 2. Customizable UI 3. Customizable workflow I have thought about an approach to achieve this, I want you to review this and make suggestions: Entity objects should be plain objects and will hold just data Separate Entity model and DB Schema by using an framework (like NHibernate?). This will allow easy modification of entity objects. Business logic to fetch/modify entities has to be granular enough so that they can be invoked as part of the workflow. Business objects should not hold any state, and hence will contain only static methods The workflow will decide depending upon the "state" of an entity/entities which methods on business object/objects to invoke. The workflow should obtain the results of the processing and then pass on the business objects to the appropriate UI screen. The UI screen has to contain instructions about how to display a given entity/entites. Possibly the UI has to be generated dynamically based on a set of UI instructions. (like XUL) What do you think about this approach? Suggest which existing frameworks (like NHiberante, Window Workflow) fit into this model, so that I will not spend time on coding these frameworks Also suggest is there any asp.net framework that can generate dynamic asp.net ajax pages based on a set of UI instructions (like Mozilla XUL)? I have recently been exploring Apache Ofbiz and was impressed by its ability to customize most areas of the application: UI, workflow, entities. Is there any similar (not necessarily an ERP system) application developed in C#/.Net which offers a similar level of customization? I am looking for examples of applications developed in C# that are highly customizable in terms of UI, Workflow and Entity Model

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