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  • 'Static/Constant' business ojects

    - by UpTheCreek
    I don't quite know how to ask this question, so I'll phase it as an example: Imagine in an application you have a Country object. There are two properties of this object: Name, and a 'Bordering Countries' collection. More properties might be added later, but it will be the kind of information that would change very rarely (e.g. changes of country names/borders) Lets say this application needs to know about all of the countries in the world. Where would you store these object's state? How would you new them up? It seems silly to store all this state in the DB, since it won't change very often. One option might be to have an abstract 'country' base object, and have a class for each country inheriting from this with the details of each country. But this doesn't seem quite right to me. What is the proper way of dealing with these kinds of objects?

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  • How many databases to support eCommerce?

    - by Terry Lorber
    I have a system with two databases, one that the customer-facing website uses, the second that is used by the "backroom" order-fulfillment system. I've been asked to run queries from the website to the backroom system. I'd rather not, it seems risky to allow web-based request to run unheeded on the internal system. Additionally, this means opening up routing in the firewall to allow external connections to the internal server. What's the best practice for eCommerce? Run the entire company off of one database? Or individual databases for each system, and middleware to connect them? Sometimes it might be necessary for the web application to pull date from the internal system, but not based on an HTTP request from the internet. I'm sure the best answer is "it depends!" So, if people have a rule of thumb for when to use middleware and when not to, I'd like to here it.

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  • Determining Best Table Structure for MySQL Performance

    - by Joe Majewski
    I'm working on a browser-based RPG for one of my websites, and right now I'm trying to determine the best way to organize my SQL tables for performance and maintenance. Here's my question: Does the number of columns in an SQL table affect the speed in which it can be queried? I am not a newbie when it comes to PHP or MySQL. I used to develop things with the common goal of getting them to work, but I've recently advanced to the stage where a functional program is not good enough unless it's fast and reliable. Anyways, right now I have a members table that has around 15 columns. It contains information such as the player's username, password, email, logins, page views, etcetera. It doesn't contain any information on the player's progress in the game, however. If I added columns for things such as army size, gold, turns, and whatnot, then it could easily rise to around 40 or 50 total columns. Oh, and my database structure IS normalized. Will a table with 50 columns that gets constantly queried be a bad idea? Should I split it into two tables; one for the user's general information and one for the user's game statistics? I know I could check the query time myself, but I haven't actually created the tables yet and I think I'd be better off with some professional advice on this important decision for my game. Thank you for your time! :)

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  • What strategies are efficient to handle concurrent reads on heterogeneous multi-core architectures?

    - by fabrizioM
    I am tackling the challenge of using both the capabilities of a 8 core machine and a high-end GPU (Tesla 10). I have one big input file, one thread for each core, and one for the the GPU handling. The Gpu thread, to be efficient, needs a big number of lines from the input, while the Cpu thread needs only one line to proceed (storing multiple lines in a temp buffer was slower). The file doesn't need to be read sequentially. I am using boost. My strategy is to have a mutex on the input stream and each thread locks - unlocks it. This is not optimal because the gpu thread should have a higher precedence when locking the mutex, being the fastest and the most demanding one. I can come up with different solutions but before rush into implementation I would like to have some guidelines. What approach do you use / recommend ?

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  • Single-Page Web Apps: Client-side datastores & server persistence

    - by fig-gnuton
    How should client-side datastores & persistence be handled in a single-page web application? Global vars vs. DI/IoC: Should datastores be assigned to global variables so any part of the application can access them? Or should they be dependency injected where required? Server persistence: Assuming a datastore's data needn't always be persisted to the server immediately, should the datastore itself handle persistence? If not, then what class should handle persistence and how should the persistence class fit into the client-side architecture overall? Is the datastore considered the model in MVC, or is it something else since it just stores raw data?

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  • Premium Services - Ad blocker legal or illegal?

    - by René
    Ok, maybe thats kind of a stupid question. But let's try to get an answer. I'm building a Desktop Solution for an existing web service. That web service is only available without ads when you pay for a premium account. Would it be illegal when I block this ads in my Desktop Application? When you use this web service over the browser, every user has the chance to block ads with adblocker addons. So why not block this stuff in my Desktop Application?

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  • How to create a generic method in C# that's all applicable to many types - ints, strings, doubles et

    - by satyajit
    Let's I have a method to remove duplicates in an integer Array public int[] RemoveDuplicates(int[] elems) { HashSet<int> uniques = new HashSet<int>(); foreach (int item in elems) uniques.Add(item); elems = new int[uniques.Count]; int cnt = 0; foreach (var item in uniques) elems[cnt++] = item; return elems; } How can I make this generic such that now it accepts a string array and remove duplicates in it? How about a double array? I know I am probably mixing things here in between primitive and value types. For your reference the following code won't compile public List<T> RemoveDuplicates(List<T> elems) { HashSet<T> uniques = new HashSet<T>(); foreach (var item in elems) uniques.Add(item); elems = new List<T>(); int cnt = 0; foreach (var item in uniques) elems[cnt++] = item; return elems; } The reason is that all generic types should be closed at run time. Thanks for you comments

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  • Does OOP make sense for small scripts?

    - by Fabian
    I mostly write small scripts in python, about 50 - 250 lines of code. I usually don't use any objects, just straightforward procedural programming. I know OOP basics and I have used object in other programming languages before, but for small scripts I don't see how objects would improve them. But maybe that is just my limited experience with OOP. Am I missing something by not trying harder to use objects, or does OOP just not make a lot of sense for small scripts?

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  • Should I be using the command pattern? Seems like a lot of work...

    - by Fedor
    My Room class has a lot of methods I used before I decided to use the command pattern. Previously, I was invoking a lot of commands and now it seems I have to make a method in my roomParser class for every method. If I wanted to invoke say, setHotelCode I would have to create a method in roomParser that iterates through and invokes the method. Is this the way I should be using the command pattern? <?php interface Parseable { public function parse( $arr, $dept ); } class Room implements Parseable { protected $_adults; protected $_kids; protected $_startDate; protected $_endDate; protected $_hotelCode; protected $_sessionNs; protected $_minRate; protected $_maxRate; protected $_groupCode; protected $_rateCode; protected $_promoCode; protected $_confCode; protected $_currency = 'USD'; protected $_soapAction; protected $_soapHeaders; protected $_soapServer; protected $_responseXml; protected $_requestXml; public function __construct( $startdate,$enddate,$rooms=1,$adults=2,$kids=0 ) { $this->setNamespace(SESSION_NAME); $this->verifyDates( $startdate, $enddate ); $this->_rooms= $rooms; $this->_adults= $adults; $this->_kids= $kids; $this->setSoapAction(); $this->setRates(); } public function parse( $arr, $dept ) { $this->_price = $arr * $dept * rand(); return $this; } public function setNamespace( $namespace ) { $this->_sessionNs = $namespace; } private function verifyDates( $startdate, $enddate ) {} public function setSoapAction( $str= 'CheckAvailability' ) { $this->_soapAction = $str; } public function setRates( $rates='' ) { } public function setHotelCode($code ) { $this->_hotelCode = $code; } private function getSoapHeader() { return '<?xml version="1.0" encoding="utf-8"?> <soap:Header> </soap:Header>'; } private function getSoapFooter() { return '</soap:Envelope>'; } private function getSource() { return '<POS> <Source><RequestorId ID="" ID_Context="" /></Source> </POS>'; } function requestXml() { $this->_requestXml = $this->getSoapHeader(); $this->_requestXml .='<soap:Body></soap:Body>'; return $this->_requestXml; } private function setSoapHeaders ($contentLength) { $this->_soapHeaders = array('POST /url HTTP/1.1', 'Host: '.SOAP_HOST, 'Content-Type: text/xml; charset=utf-8', 'Content-Length: '.$contentLength); } } class RoomParser extends SplObjectStorage { public function attach( Parseable $obj ) { parent::attach( $obj ); } public function parseRooms( $arr, $dept ) { for ( $this->rewind(); $this->valid(); $this->next() ) { $ret = $this->current()->parse( $arr, $dept ); echo $ret->getPrice(), PHP_EOL; } } } $arrive = '12/28/2010'; $depart = '01/02/2011'; $rooms = new RoomParser( $arrive, $depart); $rooms->attach( new Room( '12/28/2010', '01/02/2011') ); $rooms->attach( new Room( '12/29/2010', '01/04/2011') ); echo $rooms->count(), ' Rooms', PHP_EOL; Edit: I'm thinking it may be easier if I made the RoomParser less generic by storing properties that all the objects will share. Though I'll probably have to make methods if I want to override for a certain object.

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  • Voting Script, Possibility of Simplifying Database Queries

    - by Sev
    I have a voting script which stores the post_id and the user_id in a table, to determine whether a particular user has already voted on a post and disallow them in the future. To do that, I am doing the following 3 queries. SELECT user_id, post_id from votes_table where postid=? AND user_id=? If that returns no rows, then: UPDATE post_table set votecount = votecount-1 where post_id = ? Then SELECT votecount from post where post_id=? To display the new votecount on the web page Any better way to do this? 3 queries are seriously slowing down the user's voting experience Edit In the votes table, vote_id is a primary key In the post table, post_id is a primary key. Any other suggestions to speed things up?

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  • designing database tables using JDBC

    - by Noona
    I am creating a users table using JDBC and mysql, each user has a permissions list that comprises Integer values, I am wondering if I should use an array for storing these values and then have only 1 record for this user in the table, or simply create a new table that comprises 2 columns: user ID and permissions, and then have multiple records for each user that specify the user name in one columns and one permission value in the second column, the second option seems to be redundant since a permission value is a simple object that isn't associated with any other objects (like a student and courses list for example, because the course is associated with many other objects, like grade, teacher, etc, so in this case it is natural to have multiple records), but the first one seems to be a bit unnatural to me, so if someone has experience with these things and direct me? thanks

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  • How to handle expired items?

    - by Mark
    My site allows users to post things on the site with an expiry date. Once the item has expired, it will no longer be displayed in the listings. Posts can also be closed, canceled, or completed. I think it would be be nicest just to be able to check for one attribute or status ("is active") rather than having to check for [is not expired, is not completed, is not closed, is not canceled]. Handling the rest of those is easy because I can just have one "status" field which is essentially an enum, but AFAIK, it's impossible to set the status to "expired" as soon as that time occurs. How do people typically handle this?

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  • Approaching Java from a Ruby perspective

    - by Travis
    There are plenty of resources available to a Java developer for getting a jump-start into Ruby/Rails development. The reverse doesn't appear to be true. What resources would you suggest for getting up-to-date on the current state of java technologies? How about learning how to approach DRY (don't repeat yourself) without the use of metaprogramming? Or how to approach various scenarios where a ruby developer is used to passing in a function (proc/lambda/block) as an argument (callbacks, etc)?

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  • Why does std::map operator[] create an object if the key doesn't exist?

    - by n1ck
    Hi, I'm pretty sure I already saw this question somewhere (comp.lang.c++? Google doesn't seem to find it there either) but a quick search here doesn't seem to find it so here it is: Why does the std::map operator[] create an object if the key doesn't exist? I don't know but for me this seems counter-intuitive if you compare to most other operator[] (like std::vector) where if you use it you must be sure that the index exists. I'm wondering what's the rationale for implementing this behavior in std::map. Like I said wouldn't it be more intuitive to act more like an index in a vector and crash (well undefined behavior I guess) when accessed with an invalid key? Refining my question after seeing the answers: Ok so far I got a lot of answers saying basically it's cheap so why not or things similar. I totally agree with that but why not use a dedicated function for that (I think one of the comment said that in java there is no operator[] and the function is called put)? My point is why doesn't map operator[] work like a vector? If I use operator[] on an out of range index on a vector I wouldn't like it to insert an element even if it was cheap because that probably mean an error in my code. My point is why isn't it the same thing with map. I mean, for me, using operator[] on a map would mean: i know this key already exist (for whatever reason, i just inserted it, I have redundancy somewhere, whatever). I think it would be more intuitive that way. That said what are the advantage of doing the current behavior with operator[] (and only for that, I agree that a function with the current behavior should be there, just not operator[])? Maybe it give clearer code that way? I don't know. Another answer was that it already existed that way so why not keep it but then, probably when they (the ones before stl) choose to implement it that way they found it provided an advantage or something? So my question is basically: why choose to implement it that way, meaning a somewhat lack of consistency with other operator[]. What benefit do it give? Thanks

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  • Unexpected space between DIV elements

    - by jon
    my code for the php page displaying the divs <?php session_start(); require_once("classlib/mainspace.php"); if (isset($_SESSION['username'])==FALSE) { header("location:login.php"); } $user = new User($_SESSION['username']); ?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <link rel="stylesheet" type="text/css" href="style/style.css" /> <title>SimpleTask - Home</title> </head> <body> <div id="main"> <div id="menu"> <div id="items"> <ul> <li><a href="home.php">home</a></li> <li>&bull;</li> <li><a href="projects.php">my projects</a></li> <li>&bull;</li> <li><a href="comments.php">my comments</a></li> </ul> </div> <div id="user"> <p>Welcome, <?php echo $user->GetRealName(); ?><br/><a href="editprofile.php">edit profile</a> &bull; <a href="logout.php">logout</a></p> </div> </div> <div id="content"> <h1>HOME</h1> </div> <div id="footer"> <p>footer text goes here here here here</p> </div> </div> </body> </html> and you can find my CSS here http://tasker.efficaxdevelopment.com/style/style.css and to view the live page go here http://tasker.efficaxdevelopment.com/login.php username:admin password:password

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  • Implementing a live voting system

    - by Will Eddins
    I'm looking at implementing a live voting system on my website. The website provides a live stream, and I'd like to be able to prompt viewers to select an answer during a vote initiated by the caster. I can understand how to store the data in a mySQL database, and how to process the answers. However: How would I initially start the vote on the client-side and display it? Should a script be running every few seconds on the page, checking another page to see if a question is available for the user? Are there any existing examples of a real-time polling system such as what I'm looking at implementing?

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  • Help with MySQL database structure - user notification system

    - by Simon
    Hi, I'd like to send global notifications to my users (1000+ users) and allow them to close the notification box once they have read the message. Basically I may send one notification per week globally ie/ each user get the same message and they are not personal in nature. What is the best way to achieve this? Create 2 tables: **tb_messages** message_id massage_title message_content **tb_read_messages** user_id message_id is-read That way i can just show each user the current notifications that are not read? select * from tb_read_messages WHERE user_id = $user_id AND is-read = no OR is there a more efficient way? Thanks!!!

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  • When NOT to use MVVM?

    - by Vitalij
    I have started using MVVM pattern recently. I have had several projects where I used it and with every new one, I start to see that it will fit great within that new project. And now I start to ask myself are there situation when it's better NOT to use MVVM. Or is it such a nice pattern which you can use anywhere? Could you please describe several scenarios where MVVM wouldn't be the best choice?

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  • Buffering db inserts in multithreaded program

    - by Winter
    I have a system which breaks a large taks into small tasks using about 30 threads as a time. As each individual thread finishes it persists its calculated results to the database. What I want to achieve is to have each thread pass its results to a new persisance class that will perform a type of double buffering and data persistance while running in its own thread. For example, after 100 threads have moved their data to the buffer the persistance class then the persistance class swaps the buffers and persists all 100 entries to the database. This would allow utilization of prepared statements and thus cut way down on the I/O between the program and the database. Is there a pattern or good example of this type of multithreading double buffering?

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  • New or not so well-known paradigms, syntax features and behaviours of programming languages?

    - by George B
    I've designed some educational programming languages and interpreters for them, but my problem always was that they ended up "normal" and "boring", mostly similar to some kind of existing language (ASM and BASIC). I find it really hard to come up with new ideas for syntax features, "neat things" and new or very modified programming paradigms for it. I always thought that it was hard to come up with good new things not fun/useless new things for this case. I wondered if you could help me out with your creativity: What features in terms of language syntax and built-in functions as well as maybe even new paradigms can I work into my language to keep it useless but more fun, enjoyable, interesting and/or different to program in?

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  • Unique constraint on more than 10 columns

    - by tk
    I have a time-series simulation model which has more than 10 input variables. The number of distinct simulation instances would be more than 1 million, and each simulation instance generates a few output rows every day. To save the simulation result in a relational database, i designed tables like this. Table SimulationModel { simul_id : integer (primary key), input0 : string or numeric, input1 : string or numeric, ...} Table SimulationOutput { dt : DateTime (primary key), simul_id : integer (primary key), output0 : numeric, ...} My question is, is it fine to put an unique constraint on all of the input columns of SimulationModel table? If it is not a good idea, then what kind of other options do i have to make sure each model is unique?

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  • What is the MVC version of this code?

    - by Ian Boyd
    i'm trying to wrap my head around how to enterprise up my code: taking a simple routine and splitting it up into 5 or 6 methods in 3 or 4 classes. i quickly came up three simple examples of code how i currently write it. Could someone please convert these into an MVC/MVP obfuscated version? Example 1: The last name is mandatory. Color the text box red if nothing is entered. Color it green if stuff is entered: private void txtLastname_TextChanged(object sender, EventArgs e) { //Lastname mandatory. //Color pinkish if nothing entered. Greenish if entered. if (txtLastname.Text.Trim() == "") { //Lastname is required, color pinkish txtLastname.BackColor = ControlBad; } else { //Lastname entered, remove the coloring txtLastname.BackColor = ControlGood; } } Example 2: The first name is optional, but try to get it. We'll add a bluish tint to this "try to get" field: private void txtFirstname_TextChanged(object sender, EventArgs e) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (txtFirstname.Text == "") { //Nothing there, hint it blue txtFirstname.BackColor = ControlRequired; } else if (txtFirstname.Text.Trim() == "") { //They entered spaces - bad user! txtFirstname.BackColor = ControlBad; } else { //Entered stuff, remove coloring txtFirstname.BackColor = SystemColors.Window; } } Example 3 The age is totally optional. If an age is entered, it better be valid: private void txtAge_TextChanged(object sender, EventArgs e) { //Age is optional, but if entered it better be valid int nAge = 0; if (Int32.TryParse(txtAge.Text, out nAge)) { //Valid integer entered if (nAge < 0) { //Negative age? i don't think so txtAge.BackColor = ControlBad; } else { //Valid age entered, remove coloring txtAge.BackColor = SystemColors.Window; } } else { //Whatever is in there: it's *not* a valid integer, if (txtAge.Text == "") { //Blank is okay txtAge.BackColor = SystemColors.Window; } else { //Not a valid age, bad user txtAge.BackColor = ControlBad; } } } Every time i see MVC code, it looks almost like random splitting of code into different methods, classes, and files. i've not been able to determine a reason or pattern to their madness. Without any understanding of they why it's being one some way, it makes no sense. And using the words model, view, controller and presenter, like i'm supposed to know what that means, doesn't help. The model is your data. The view shows data on screen. The controller is used to carry out the users actions And oranges taste orangy. Here's my attempt at splitting things up in order to make the code more difficult to follow. Is this anywhere close to MVC? private void txtFirstname_TextChanged(object sender, EventArgs e) { FirstnameTextChangedHandler(sender, e); } private void FirstnameTextChangedHandler(sender, e) { string firstname = GetFirstname(); Color firstnameTextBoxColor = GetFirstnameTextBoxColor(firstname); SetFirstNameTextBoxColor(firstnameTextBoxColor); } private string GetFirstname() { return txtFirstname.Text; } private Color GetFirstnameTextBoxColor(string firstname) { //Firstname can be blank. //Hint them that they should *try* to get it with a bluish color. //If they do enter stuff: it better be not all spaces. if (firstname == "") { //Nothing there, hint it blue return GetControlRequiredColor(); } else if (firstname.Trim() == "") { //They entered spaces - bad user! return GetControlBadColor(); } else { //Entered stuff, remove coloring return GetControlDefaultColor(); } } private Color GetControlRequiredColor() { return ControlRequired; } private Color GetControlBadColor() { return ControlBad; } private Color GetControlGoodColor() { return ControlGood; } //am i doin it rite i've obfuscated the code, but it's still altogether. The next step in the MVC obfuscation, i gather, is to hide the code in 3 or 4 different files. It's that next step that i don't understand. What is the logical separation of which functions are moved into what other classes? Can someone translate my 3 simple examples above into full fledged MVC obfuscation? Edit: Not ASP/ASP.NET/Online. Pretend it's on a desktop, handheld, surface, kiosk. And pretend it's language agnostic.

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  • Application that depends heavily on stored procedures

    - by PieterG
    We currently have an application that depends largely on stored procedures. There is a heavy use of temp tables. It's an extremely large application. Facing this situation, I would like to use Entity Framework or Linq2Sql for a rewrite. I might consider using Fluent Hibernate or Subsonic, as i've used them quite extensively in the past. I've had problems with Linq2Sql generating the return types for the stored procedures because of the usage of the temp tables, and I think it's cumbersome to go and change all the stored procedures from temp tables to in-memory tables. Considering the 2 choices that I want to make, which one of the 2 is the best route to go and why? If my choices are extremely idiotic, please provide alternatives. Edit: The reason for the question and the change is that the data access layer is non-existent and was built 10 years ago. We currently still run into a lot of issues with it. I don't want to divulge too much, but if you saw it, your eyes would start bleeding :)

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  • Would this constructor be acceptable practice?

    - by Robb
    Let's assume I have a c++ class that have properly implemented a copy constructor and an overloaded = operator. By properly implemented I mean they are working and perform a deep copy: Class1::Class1(const Class1 &class1) { // Perform copy } Class1& Class1::operator=(const Class1 *class1) { // perform copy return *this; } Now lets say I have this constructor as well: Class1::Class1(Class1 *class1) { *this = *class1; } My question is would the above constructor be acceptable practice? This is code that i've inherited and maintaining.

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