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• RESTful API design - should a PUT return related data?

  - by alexmcroberts

  I have an API which allows a user to update their system status; and a separate call to retrieve system status updates from other users. Would it make sense to unify them under a PUT request where a user would request a PUT update with their own status update, and they would receive the status updates of other users? My solution would allow the PUT request to call the GET request method internally. The reason behind this is that when a user updates their system status they should be informed of other users status immediately, and I don't feel that having 2 seperate requests is necessary - and should be optional. I intend to keep the GET request for other users status as a status update for a user is not necessarily required in order to retrieve other users status', but once they update their own status is it vital that they get information about other users.

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• What is a good design pattern / lib for iOS 5 to synchronize with a web service?

  - by Junto

  We are developing an iOS application that needs to synchronize with a remote server using web services. The existing web services have an "operations" style rather than REST (implemented in WCF but exposing JSON HTTP endpoints). We are unsure of how to structure the web services to best fit with iOS and would love some advice. We are also interested in how to manage the synchronization process within iOS. Without going into detailed specifics, the application allows the user to estimate repair costs at a remote site. These costs are broken down by room and item. If the user has an internet connection this data can be sent back to the server. Multiple photographs can be taken of each item, but they will be held in a separate queue, which sends when the connection is optimal (ideally wifi). Our backend application controls the unique ids for each room and item. Thus, each time we send these costs to the server, the server echoes the central database ids back, thus, that they can be synchronized in the mobile app. I have simplified this a little, since the operations contract is actually much larger, but I just want to illustrate the basic requirements without complicating matters. Firstly, the web service architecture: We currently have two operations: GetCosts and UpdateCosts. My assumption is that if we used a strict REST architecture we would need to break our single web service operations into multiple smaller services. This would make the services much more chatty and we would also have to guarantee a delivery order from the app. For example, we need to make sure that containing rooms are added before the item. Although this seems much more RESTful, our perception is that these extra calls are expensive connections (security checks, database calls, etc). Does the type of web api (operation over service focus) determine chunky vs chatty? Since this is mobile (3G), are we better handling lots of smaller messages, or a few large ones? Secondly, the iOS side. What is the current advice on how to manage data synchronization within the iOS (5) app itself. We need multiple queues and we need to guarantee delivery order in each queue (and technically, ordering between queues). The server needs to control unique ids and other properties and echo them back to the application. The application then needs to update an internal database and when re-updating, make sure the correct ids are available in the update message (essentially multiple inserts and updates in one call). Our backend has a ton of business logic operating on these cost estimates. We don't want any of this in the app itself. Currently the iOS app sends the cost data, and then the server echoes that data back with populated ids (and other data). The existing cost data is deleted and the echoed response data is added to the client database on the device. This is causing us problems, because any photos might not have been sent, but the original entity tree has been removed and replaced. Obviously updating the costs tree rather than replacing it would remove this problem, but I'm not sure if there are any nice xcode libraries out there to do such things. I welcome any advice you might have.

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• What is the best practice for website design and markup now that mobile browsers are common?

  - by Jonathan Drain

  Back in 2008, smartphones were a small market and it was commonplace for sites to be designed for a fixed width - say, 900px or 960px - with the page centered if the browser window was larger. Many designers said fluid width was better, but since user screens typically varied between 1024x768 and 1920x1080, fluid width allowed longer line length than is optimal for ease of reading, and so many sites (including Stack Exchange) use fixed width. Now that mobile devices are common, what is the the best approach to support both desktop and mobile browsers? Establish a separate mobile site (e.g: mobile.example.com) Serve a different CSS to mobile devices; if so how? Server-side browser sniffing, or a @media rule? Use Javascript or something to adapt the website dynamically to the client? Should all websites be expected to be responsive? Some kind of fluid layout Something else?

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• Is there really anything to gain with complex design? [duplicate]

  - by SB2055

  This question already has an answer here: What is enterprise software, exactly? 8 answers I've been working for a consulting firm for some time, with clients of various sizes, and I've seen web applications ranging in complexity from really simple: MVC Service Layer EF DB To really complex: MVC UoW DI / IoC Repository Service UI Tests Unit Tests Integration Tests But on both ends of the spectrum, the quality requirements are about the same. In simple projects, new devs / consultants can hop on, make changes, and contribute immediately, without having to wade through 6 layers of abstraction to understand what's going on, or risking misunderstanding some complex abstraction and costing down the line. In all cases, there was never a need to actually make code swappable or reusable - and the tests were never actually maintained past the first iteration because requirements changed, it was too time-consuming, deadlines, business pressure, etc etc. So if - in the end - testing and interfaces aren't used rapid development (read: cost-savings) is a priority the project's requirements will be changing a lot while in development ...would it be wrong to recommend a super-simple architecture, even to solve a complex problem, for an enterprise client? Is it complexity that defines enterprise solutions, or is it the reliability, # concurrent users, ease-of-maintenance, or all of the above? I know this is a very vague question, and any answer wouldn't apply to all cases, but I'm interested in hearing from devs / consultants that have been in the business for a while and that have worked with these varying degrees of complexity, to hear if the cool-but-expensive abstractions are worth the overall cost, at least while the project is in development.

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• Language Design: Are languages like phyton and coffescript really more comprehendable?

  - by kittensatplay

  the "Verbally Readable !== Quicker Comprehension" arguement on http://ryanflorence.com/2011/case-against-coffeescript/ is really potent and interesting. i and im sure other would be very interested in evidence arguing against this. there's clear evidence for this and i believe it. ppl naturally think in images, not words, so we should be designing languages dissimilar to human language like english, french, whatever. being "readable" is quicker comprehension. most articles on wikipedia are not readable as they are long, boring, dry, sluggish, very very wordy, and because wikipedia documents a ton of info, is not especially helpful when compared to much more helpful sites with more practical, useful, and relevant info. but languages like phyton and coffescript are "verbally readable" in that they are closer to the english language syntax, and programming firstly and mainly in python, im not so sure this is really a good thing. the second interesting argument is that coffeescript is an intermediator so thereby another step between to ends, which may increase chances of bugs. while coffeescript has other practical benefits, this question is focused specifically on evidence showing support for the counter-case of language "readability"

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• In PHP, what are the different design patterns to implement OO controllers as opposed to procedural controllers?

  - by Ryan

  For example, it's very straightforward to have an index.php controller be a procedural script like so: <?php //include classes and functions //get some data from the database //and/or process a form submission //render HTML using your template system ?> Then I can just navigate to http://mysite.com/index.php and the above procedural script is essentially acting as a simple controller. Here the controller mechanism is a basic procedural script. How then do you make controllers classes instead of procedural scripts? Must the controller class always be tied to the routing mechanism?

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• What is a good design pattern and terminology for decoupling output?

  - by User

  I have a program where I want to save some data record. And I want the output type to be flexible such that I could save the data record to a text file, xml file, database, push to a webservice. My take on it would be to create an interface such as DataStore with a Save() method, and the concrete subclasses such as TextFileDataStore, DatabaseDataStore, etc. What is the proper name/terminology for this type of pattern (I'm using the term "DataStore", log4net names things "appenders", .net they talk about "providers" and "persistence")? I want to come up with good class names (and method names) that fit with a convention if there is one. can you point me to a decent example, preferably in C#, C++, or java? Update Managed to find this stack overflow question, Object persistence terminology: 'repository' vs. 'store' vs. 'context' vs. 'retriever' vs. (…), which captures the terminology part of my question pretty well although there's not a decent answer yet.

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• Language Design: Are languages like Python and CoffeeScript really more comprehensible?

  - by kittensatplay

  The "Verbally Readable !== Quicker Comprehension" argument on http://ryanflorence.com/2011/case-against-coffeescript/ is really potent and interesting. I and I'm sure others would be very interested in evidence arguing against this. There's clear evidence for this and I believe it. People naturally think in images, not words, so we should be designing languages that aren't similar to human language like English, French, whatever. Being "readable" is quicker comprehension. Most articles on Wikipedia are not readable as they are long, boring, dry, sluggish and very very wordy. Because Wikipedia documents a ton of info, it is not especially helpful when compared to sites with more practical, useful and relevant info. Languages like Python and CoffeScript are "verbally readable" in that they are closer to English syntax. Having programmed firstly and mainly in Python, I'm not so sure this is really a good thing. The second interesting argument is that CoffeeScript is an intermediator, a step between two ends, which may increase the chance of bugs. While CoffeeScript has other practical benefits, this question specifically requests evidence showing support for the counter-case of language "readability"

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• Are there any good books on how to design software?

  - by nc01

  I've been programming for a while and I think I write clean code. But I do this by hacking away, tinkering and testing things until I feel good about the functionality, and then coming in and refactoring, refactoring, refactoring. I tend to write mostly in PHP, Java, and C. Are there any good books that will help me learn to visualize things better and not code everything as if in an infinite REPL loop? Thanks.

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• In a team practicing Domain Driven Design, should the whole team participate in Stakeholder meetings?

  - by thirdy

  In my experience, a Software Development Team that comprises: 1 Project Manager 1 Tech Lead 1 - 2 Senior Dev 2 - 3 Junior Dev (Fresh grad) Only the Tech Lead & PM (and/or Senor Dev/s) will participate in a meeting with Clients, Domain Experts, Client's technical resource. I can think of the ff potential pitfalls: Important info gets lost Human error (TL/PM might forgot to disseminate info due to pressure or plain human error) Non-verbal info (maybe a presentation using a diagram presented by Domain Expert) Maintaining Ubiquitous language is harder to build since not all team members get to hear the non-dev persons Potential of creative minds are not fully realized (Personally, I am more motivated to think/explore when I am involved with these important meetings) Advantages of this approach: Only one point of contact Less time spent on meetings? Honestly, I am biased & against this approach. I would like to hear your opinions. Is this how you do it in your team? Thanks in advance!

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• Running Mixed Physical and Virtual Exalogic Elastic Cloud Software Versions in an Exalogic Rack is now Supported

  - by csoto

  Although it was not supported on older versions, now as of EECS 2.0.6, an Exalogic rack can be configured in a mixed-mode: half virtual and half physical Linux: Flexibility to have physical and virtual environments on same rack. For example, production on physical and test/dev on virtual. Exalogic Control manages the virtual compute nodes on the rack. Physical compute nodes are managed manually (including PKeys). Option to change full physical to hybrid and hybrid to full virtual rack. User has an option to choose either the top or bottom nodes for physical or virtual deployment. For further information about how the compute nodes can be split up on the rack (into bottom or top half) to run either Oracle Virtual Server (OVS "hypervisor") or Oracle Linux, please take a look at MOS Note 1536945.1. Note: Solaris is not yet supported in the mixed configuration.

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• Which is a better design pattern for a database wrapper: Save as you go or Save when your done?

  - by izuriel

  I know this is probably a bad way to ask this question. I was unable to find another question that addressed this. The full question is this: We're producing a wrapper for a database and have two different viewpoints on managing data with the wrapper. The first is that all changes made to a data object in code must be persisted in the database by calling a "save" method to actually save the changes. The other side is that these changes should be save as they are made, so if I change a property it's saved, I change another it's save as well. What are the pros/cons of either choice and which is the "proper" way to manage the data?

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• Requring static class setter to be called before constructor, bad design?

  - by roverred

  I have a class, say Foo, and every instance of Foo will need and contain the same List object, myList. Since every class instance will share the same List Object, I thought it would be good to make myList static and use a static function to set myList before the constructor is called. I was wondering if this was bad, because this requires the setter to be called before the constructor? If the person doesn't, the program will crash. Alternative way would be passing myList every time.

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• Advice on database design / SQL for retrieving data with chronological order

  - by Remnant

  I am creating a database that will help keep track of which employees have been on a certain training course. I would like to get some guidance on the best way to design the database. Specifically, each employee must attend the training course each year and my database needs to keep a history of all the dates on which they have attend the course in the past. The end user will use the software as a planning tool to help them book future course dates for employees. When they select a given employee they will see: (a) Last attendance date (b) Projected future attendance date(i.e. last attendance date + 1 calendar year) In terms of my database, any given employee may have multiple past course attendance dates: EmpName AttandanceDate Joe Bloggs 1st Jan 2007 Joe Bloggs 4th Jan 2008 Joe Bloggs 3rd Jan 2009 Joe Bloggs 8th Jan 2010 My question is what is the best way to set up the database to make it easy to retrieve the most recent course attendance date? In the example above, the most recent would be 8th Jan 2010. Is there a good way to use SQL to sort by date and pick the MAX date? My other idea was to add a column called ‘MostRecent’ and just set this to TRUE. EmpName AttandanceDate MostRecent Joe Bloggs 1st Jan 2007 False Joe Bloggs 4th Jan 2008 False Joe Bloggs 3rd Jan 2009 False Joe Bloggs 8th Jan 2010 True I wondered if this would simplify the SQL i.e. SELECT Joe Bloggs WHERE MostRecent = ‘TRUE’ Also, when the user updates a given employee’s attendance record (i.e. with latest attendance date) I could use SQL to: Search for the employee and set the MostRecent value to FALSE Add a new record with MostRecent set to TRUE? Would anybody recommended either method over the other? Or do you have a completely different way of solving this problem?

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• Is this an acceptable UI design decision?

  - by DVK

  OK, while I'm on record as stating that StackExchange UI is pretty much one of the best websites and overall GUIs that I have ever seen as far as usability goes, there's one particular aspect of the trilogy that bugs me. For an example, head on to http://meta.stackoverflow.com . Look at the banner on top (the one that says "reminder -- it's April Fool's Day depending on your time zone!"). Personally, I feel that this is a "make the user do the figuring out work" anti-pattern (whatever it's officially called) - namely, instead of making your app smart enough to only present a certain mode of operations in the conditions when that mode is appropriate, you simply turn on the mode full on and put an explanation to the user of why the mode is on when it should not be (in this particular example, the mode is of course displaying the unicorn gravatars starting with 00:00 in the first timezone, despite the fact that some users still live in March 31st). The Great Recalc was also handled the same way - instead of proactively telling the user "your rep was changed from X to Y" the same nearly invisible banner was displayed on meta. So, the questions are: Is there such an official anti-pattern, and if so,m what the heck do i call it? Do you have any other well-known examples of such design anti-pattern? How would you fix either the SO example I made or you your own example? Is there a pattern of fixing or must it be a case-by-case solution?

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• Object oriented design suggestion

  - by pocoa

  Here is my code: class Soldier { public: Soldier(const string &name, const Gun &gun); string getName(); private: Gun gun; string name; }; class Gun { public: void fire(); void load(int bullets); int getBullets(); private: int bullets; } I need to call all the member functiosn of Gun over a Soldier object. Something like: soldier.gun.fire(); or soldier.getGun().load(15); So which one is a better design? Hiding the gun object as a private member and access it with getGun() function. Or making it a public member? Or I can encapsulate all these functions would make the implementation harder: soldier.loadGun(15); // calls Gun.load() soldier.fire(); // calls Gun.fire() So which one do you think is the best?

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• Autocomplete or Select box? (design problem)

  - by Craig Whitley

  I'm working on a comparison website, so needless to say the search function is the primary feature of the site. I have two input text boxes and a search button. At the moment, the input text boxes use Ajax to query the database and show a drop-down box, but I'm wondering if it would be more intuitive to use a select box instead? The second box is dependant on the first, as when the first is selected theres another ajax query so only the available options for the first selection appear in the autocomplete box. Autocomplete Pros: - "Feels" right? - Looks more appealing than a select box (css design)? Cons: - the user has to be instructed on how to use the search (made to think?) - Only really works off the bat with javascript enabled. - The user may get confused if they type in what they want and no box appears (i.e., no results) Select Box Pros: - Can bring up the list of options / know whats there from the outset. - We use select boxes every day (locations etc.) so we're used to how they work. (more intuitive?) Cons: - Can look a little unaesthetic when theres too many options to choose from. I'm thinking maybe at most around 100 options for my site over time. Any thoughts on how I could go about this would be appreciated!

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• Progress Bar design patterns?

  - by shoosh

  The application I'm writing performs a length algorithm which usually takes a few minutes to finish. During this time I'd like to show the user a progress bar which indicates how much of the algorithm is done as precisely as possible. The algorithm is divided into several steps, each with its own typical timing. For instance- initialization (500 milli-sec) reading inputs (5 sec) step 1 (30 sec) step 2 (3 minutes) writing outputs (7 sec) shutting down (10 milli-sec) Each step can report its progress quite easily by setting the range its working on, say [0 to 150] and then reporting the value it completed in its main loop. What I currently have set up is a scheme of nested progress monitors which form a sort of implicit tree of progress reporting. All progress monitors inherit from an interface IProgressMonitor: class IProgressMonitor { public: void setRange(int from, int to) = 0; void setValue(int v) = 0; }; The root of the tree is the ProgressMonitor which is connected to the actual GUI interface: class GUIBarProgressMonitor : public IProgressMonitor { GUIBarProgressMonitor(ProgressBarWidget *); }; Any other node in the tree are monitors which take control of a piece of the parent progress: class SubProgressMonitor : public IProgressMonitor { SubProgressMonitor(IProgressMonitor *parent, int parentFrom, int parentLength) ... }; A SubProgressMonitor takes control of the range [parentFrom, parentFrom+parentLength] of its parent. With this scheme I am able to statically divide the top level progress according to the expected relative portion of each step in the global timing. Each step can then be further subdivided into pieces etc' The main disadvantage of this is that the division is static and it gets painful to make changes according to variables which are discovered at run time. So the question: are there any known design patterns for progress monitoring which solve this issue?

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• Design/Architecture Advice Needed

  - by Rachel

  Summary: I have different components on homepage and each components shows some promotion to the user. I have Cart as one Component and depending upon content of the cart promotion are show. I have to track user online activities and send that information to Omniture for Report Generation. Now my components are loaded asynchronously basically are loaded when AjaxRequest is fired up and so there is not fix pattern or rather information on when components will appear on the webpages. Now in order to pass information to Omniture I need to call track function on $(document).(ready) and append information for each components(7 parameters are required by Omniture for each component). So in the init:config function of each component am calling Omniture and passing paramters but now no. of Omniture calls is directly proportional to no. of Components on the webpage but this is not acceptable as each call to Omniture is very expensive. Now I am looking for a way where in I can club the information about 7 parameters and than make one Call to Omniture wherein I pass those information. Points to note is that I do not know when the components are loaded and so there is no pre-defined time or no. of components that would be loaded. The thing is am calling track function when document is ready but components are loaded after call to Omniture has been made and so my question is Q: How can I collect the information for all the components and than just make one call to Omniture to send those information ? As mentioned, I do not know when the components are loaded as they are done on the Ajax Request. Hope I am able to explain my challenge and would appreciate if some one can provide from Design/Architect Solutions for the Challenge.

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• DDD principlers and ASP.NET MVC project design

  - by kaivalya

  Two part questions I have a product aggregate that has; Prices PackagingOptions ProductDescriptions ProductImages etc I have modeled one product repository and did not create individual repositories for any of the child classes. All db operations are handled through product repository. Am I understanding the DDD concept correctly so far? Sometimes the question comes to my mind that having a repository for lets say packaging options could make my life easier by directly fetching a the packaging option from the DB by using its ID instead of asking the product repository to find it in its PackagingOptions collection and give it to me.. Second part is managing the edit create operations using ASP.MVC frame work I am currently trying to manage all add edit remove of these child collections of product through product controller(sound right?). One challenge I am now facing is; If I edit a specific packaging option of product through mydomain/product/editpackagingoption/10 I have access to the id of the packaging option But I don't have the ID of the product it self and this forces me to write a query to first find the product that has this specific packaging option then edit that product and the revelant packaging option. I can do this as all packaging option have their unique ID but this would fail if I have collections that don't have unique ID. That feels very wrong.. The next option I thought of is sending both the product and packaging option IDs on the url like; mydomain/product/editpackagingoption/3/10 But I am not sure if that is a good design either. So I am at a point that I am a bit confused. might be having fundamental misunderstandings around all of this... I would appreciate if you bear with the long question and help me put this together. thanks!

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• Mutability design patterns in Objective C and C++

  - by Mac

  Having recently done some development for iPhone, I've come to notice an interesting design pattern used a lot in the iPhone SDK, regarding object mutability. It seems the typical approach there is to define an immutable class NSFoo, and then derive from it a mutable descendant NSMutableFoo. Generally, the NSFoo class defines data members, getters and read-only operations, and the derived NSMutableFoo adds on setters and mutating operations. Being more familiar with C++, I couldn't help but notice that this seems to be a complete opposite to what I'd do when writing the same code in C++. While you certainly could take that approach, it seems to me that a more concise approach is to create a single Foo class, mark getters and read-only operations as const functions, and also implement the mutable operations and setters in the same class. You would then end up with a mutable class, but the types Foo const*, Foo const& etc all are effectively the immutable equivalent. I guess my question is, does my take on the situation make sense? I understand why Objective-C does things differently, but are there any advantages to the two-class approach in C++ that I've missed? Or am I missing the point entirely? Not an overly serious question - more for my own curiosity than anything else.

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• C# Static constructors design problem - need to specify parameter

  - by Neil Dobson

  I have a re-occurring design problem with certain classes which require one-off initialization with a parameter such as the name of an external resource such as a config file. For example, I have a corelib project which provides application-wide logging, configuration and general helper methods. This object could use a static constructor to initialize itself but it need access to a config file which it can't find itself. I can see a couple of solutions, but both of these don't seem quite right: 1) Use a constructor with a parameter. But then each object which requires corelib functionality should also know the name of the config file, so this has to be passed around the application. Also if I implemented corelib as a singleton I would also have to pass the config file as a parameter to the GetInstance method, which I believe is also not right. 2) Create a static property or method to pass through the config file or other external parameter. I have sort of used the latter method and created a Load method which initializes an inner class which it passes through the config file in the constructor. Then this inner class is exposed through a public property MyCoreLib. public static class CoreLib { private static MyCoreLib myCoreLib; public static void Load(string configFile) { myCoreLib = new MyCoreLib(configFile); } public static MyCoreLib MyCoreLib { get { return myCoreLib; } } public class MyCoreLib { private string configFile; public MyCoreLib(string configFile) { this.configFile = configFile; } public void DoSomething() { } } } I'm still not happy though. The inner class is not initialized until you call the load method, so that needs to be considered anywhere the MyCoreLib is accessed. Also there is nothing to stop someone calling the load method again. Any other patterns or ideas how to accomplish this?

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• Database warehouse design: fact tables and dimension tables

  - by morpheous

  I am building a poor man's data warehouse using a RDBMS. I have identified the key 'attributes' to be recorded as: sex (true/false) demographic classification (A, B, C etc) place of birth date of birth weight (recorded daily): The fact that is being recorded My requirements are to be able to run 'OLAP' queries that allow me to: 'slice and dice' 'drill up/down' the data and generally, be able to view the data from different perspectives After reading up on this topic area, the general consensus seems to be that this is best implemented using dimension tables rather than normalized tables. Assuming that this assertion is true (i.e. the solution is best implemented using fact and dimension tables), I would like to seek some help in the design of these tables. 'Natural' (or obvious) dimensions are: Date dimension Geographical location Which have hierarchical attributes. However, I am struggling with how to model the following fields: sex (true/false) demographic classification (A, B, C etc) The reason I am struggling with these fields is that: They have no obvious hierarchical attributes which will aid aggregation (AFAIA) - which suggest they should be in a fact table They are mostly static or very rarely change - which suggests they should be in a dimension table. Maybe the heuristic I am using above is too crude? I will give some examples on the type of analysis I would like to carryout on the data warehouse - hopefully that will clarify things further. I would like to aggregate and analyze the data by sex and demographic classification - e.g. answer questions like: How does male and female weights compare across different demographic classifications? Which demographic classification (male AND female), show the most increase in weight this quarter. etc. Can anyone clarify whether sex and demographic classification are part of the fact table, or whether they are (as I suspect) dimension tables.? Also assuming they are dimension tables, could someone elaborate on the table structures (i.e. the fields)? The 'obvious' schema: CREATE TABLE sex_type (is_male int); CREATE TABLE demographic_category (id int, name varchar(4)); may not be the correct one.

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• C++ design question on traversing binary trees

  - by user231536

  I have a binary tree T which I would like to copy to another tree. Suppose I have a visit method that gets evaluated at every node: struct visit { virtual void operator() (node* n)=0; }; and I have a visitor algorithm void visitor(node* t, visit& v) { //do a preorder traversal using stack or recursion if (!t) return; v(t); visitor(t->left, v); visitor(t->right, v); } I have 2 questions: I settled on using the functor based approach because I see that boost graph does this (vertex visitors). Also I tend to repeat the same code to traverse the tree and do different things at each node. Is this a good design to get rid of duplicated code? What other alternative designs are there? How do I use this to create a new binary tree from an existing one? I can keep a stack on the visit functor if I want, but it gets tied to the algorithm in visitor. How would I incorporate postorder traversals here ? Another functor class?

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• SQL Server 2005 database design - many-to-many relationships with hierarchy

  - by Remnant

  Note I have completely re-written my original post to better explain the issue I am trying to understand. I have tried to generalise the problem as much as possible. Also, my thanks to the original people who responded. Hopefully this post makes things a little clearer. Context In short, I am struggling to understand the best way to design a small scale database to handle (what I perceive to be) multiple many-to-many relationships. Imagine the following scenario for a company organisational structure: Textile Division Marketing Division | | ---------------------- ---------------------- | | | | HR Dept Finance Dept HR Dept Finance Dept | | | | ---------- ---------- ---------- --------- | | | | | | | | Payroll Hiring Audit Tax Payroll Hiring Audit Accounts | | | | | | | | Emps Emps Emps Emps Emps Emps Emps Emps NB: Emps denotes a list of employess that work in that area When I first started with this issue I made four separate tables: Divisions - Textile, Marketing (PK = DivisionID) Departments - HR, Finance (PK = DeptID) Functions - Payroll, Hiring, Audit, Tax, Accounts (PK = FunctionID) Employees - List of all Employees (PK = EmployeeID) The problem as I see it is that there are multiple many-to-many relationships i.e. many departments have many divisions and many functions have many departments. Question Giving the database structure above, suppose I wanted to do the following: Get all employees who work in the Payroll function of the Marketing Division To do this I need to be able to differentiate between the two Payroll departments but I am not sure how this can be done? I understand that I could build a 'Link / Junction' table between Departments and Functions so that I can retrieve which Functions are in which Departments. However, I would still need to differentiate the Division they belong to. Research Effort As you can see I am an abecedarian when it comes to database deisgn. I have spent the last two days resaerching this issue, traversing nested set models, adjacency models, reading that this issue is known not to be NP complete etc. I am sure there is a simple solution?

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