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  • Why is debugging better in an IDE?

    - by Bill Karwin
    I've been a software developer for over twenty years, programming in C, Perl, SQL, Java, PHP, JavaScript, and recently Python. I've never had a problem I could not debug using some careful thought, and well-placed debugging print statements. I respect that many people say that my techniques are primitive, and using a real debugger in an IDE is much better. Yet from my observation, IDE users don't appear to debug faster or more successfully than I can, using my stone knives and bear skins. I'm sincerely open to learning the right tools, I've just never been shown a compelling advantage to using visual debuggers. Moreover, I have never read a tutorial or book that showed how to debug effectively using an IDE, beyond the basics of how to set breakpoints and display the contents of variables. What am I missing? What makes IDE debugging tools so much more effective than thoughtful use of diagnostic print statements? Can you suggest resources (tutorials, books, screencasts) that show the finer techniques of IDE debugging? Sweet answers! Thanks much to everyone for taking the time. Very illuminating. I voted up many, and voted none down. Some notable points: Debuggers can help me do ad hoc inspection or alteration of variables, code, or any other aspect of the runtime environment, whereas manual debugging requires me to stop, edit, and re-execute the application (possibly requiring recompilation). Debuggers can attach to a running process or use a crash dump, whereas with manual debugging, "steps to reproduce" a defect are necessary. Debuggers can display complex data structures, multi-threaded environments, or full runtime stacks easily and in a more readable manner. Debuggers offer many ways to reduce the time and repetitive work to do almost any debugging tasks. Visual debuggers and console debuggers are both useful, and have many features in common. A visual debugger integrated into an IDE also gives you convenient access to smart editing and all the other features of the IDE, in a single integrated development environment (hence the name).

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  • Why do WCF clients depend on the app.config file?

    - by routeNpingme
    Like a lot of things, I'm sure there's a good reason for this, so please help me understand... Why, by default, do WCF services store settings in app.config? This has been so frustrating trying to work with multiple Silverlight class libraries. These class libraries are supposed to be completely independent from each other, and this dependency on the app.config seems to cause the following headaches: Single Responsibility Principle - I should be able to add a reference to a class library and go. If that class library uses a service reference, this idea is shot before I even start coding against it. Muddy Configuration - To get other libraries to work, I have to copy and paste the service configurations into the "main" application configs. If an endpoint changes in any way, I can't just worry about a new version of that class DLL - I have to worry about anything that uses it, too. Complex Alternatives - Programmatically creating the endpoint isn't pretty. Period. There has to be a better way. Why doesn't WCF at least separate the service configurations into a ServiceName.config or something that gets copied to an output directory. What am I missing? How do you deal with this?

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  • Create new or update existing entity at one go with JPA

    - by Alex R
    A have a JPA entity that has timestamp field and is distinguished by a complex identifier field. What I need is to update timestamp in an entity that has already been stored, otherwise create and store new entity with the current timestamp. As it turns out the task is not as simple as it seems from the first sight. The problem is that in concurrent environment I get nasty "Unique index or primary key violation" exception. Here's my code: // Load existing entity, if any. Entity e = entityManager.find(Entity.class, id); if (e == null) { // Could not find entity with the specified id in the database, so create new one. e = entityManager.merge(new Entity(id)); } // Set current time... e.setTimestamp(new Date()); // ...and finally save entity. entityManager.flush(); Please note that in this example entity identifier is not generated on insert, it is known in advance. When two or more of threads run this block of code in parallel, they may simultaneously get null from entityManager.find(Entity.class, id) method call, so they will attempt to save two or more entities at the same time, with the same identifier resulting in error. I think that there are few solutions to the problem. Sure I could synchronize this code block with a global lock to prevent concurrent access to the database, but would it be the most efficient way? Some databases support very handy MERGE statement that updates existing or creates new row if none exists. But I doubt that OpenJPA (JPA implementation of my choice) supports it. Event if JPA does not support SQL MERGE, I can always fall back to plain old JDBC and do whatever I want with the database. But I don't want to leave comfortable API and mess with hairy JDBC+SQL combination. There is a magic trick to fix it using standard JPA API only, but I don't know it yet. Please help.

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  • File descriptor limits and default stack sizes

    - by Charles
    Where I work we build and distribute a library and a couple complex programs built on that library. All code is written in C and is available on most 'standard' systems like Windows, Linux, Aix, Solaris, Darwin. I started in the QA department and while running tests recently I have been reminded several times that I need to remember to set the file descriptor limits and default stack sizes higher or bad things will happen. This is particularly the case with Solaris and now Darwin. Now this is very strange to me because I am a believer in 0 required environment fiddling to make a product work. So I am wondering if there are times where this sort of requirement is a necessary evil, or if we are doing something wrong. Edit: Great comments that describe the problem and a little background. However I do not believe I worded the question well enough. Currently, we require customers, and hence, us the testers, to set these limits before running our code. We do not do this programatically. And this is not a situation where they MIGHT run out, under normal load our programs WILL run out and seg fault. So rewording the question, is requiring the customer to change these ulimit values to run our software to be expected on some platforms, ie, Solaris, Aix, or are we as a company making it to difficult for these users to get going? Bounty: I added a bounty to hopefully get a little more information on what other companies are doing to manage these limits. Can you set these pragmatically? Should we? Should our programs even be hitting these limits or could this be a sign that things might be a bit messy under the covers? That is really what I want to know, as a perfectionist a seemingly dirty program really bugs me.

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  • In Python, how can I find the index of the first item in a list that is NOT some value?

    - by Ryan B. Lynch
    Python's list type has an index(x) method. It takes a single parameter x, and returns the (integer) index of the first item in the list that has the value x. Basically, I need to invert the index(x) method. I need to get the index of the first value in a list that does NOT have the value x. I would probably be able to even just use a function that returns the index of the first item with a value != None. I can think of a 'for' loop implementation with an incrementing counter variable, but I feel like I'm missing something. Is there an existing method, or a one-line Python construction that can handle this? In my program, the situation comes up when I'm handling lists returned from complex regex matches. All but one item in each list have a value of None. If I just needed the matched string, I could use a list comprehension like '[x for x in [my_list] if x is not None]', but I need the index in order to figure out which capture group in my regex actually caused the match.

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  • Queries within queries: Is there a better way?

    - by mririgo
    As I build bigger, more advanced web applications, I'm finding myself writing extremely long and complex queries. I tend to write queries within queries a lot because I feel making one call to the database from PHP is better than making several and correlating the data. However, anyone who knows anything about SQL knows about JOINs. Personally, I've used a JOIN or two before, but quickly stopped when I discovered using subqueries because it felt easier and quicker for me to write and maintain. Commonly, I'll do subqueries that may contain one or more subqueries from relative tables. Consider this example: SELECT (SELECT username FROM users WHERE records.user_id = user_id) AS username, (SELECT last_name||', '||first_name FROM users WHERE records.user_id = user_id) AS name, in_timestamp, out_timestamp FROM records ORDER BY in_timestamp Rarely, I'll do subqueries after the WHERE clause. Consider this example: SELECT user_id, (SELECT name FROM organizations WHERE (SELECT organization FROM locations WHERE records.location = location_id) = organization_id) AS organization_name FROM records ORDER BY in_timestamp In these two cases, would I see any sort of improvement if I decided to rewrite the queries using a JOIN? As more of a blanket question, what are the advantages/disadvantages of using subqueries or a JOIN? Is one way more correct or accepted than the other?

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  • How do I implement configurations and settings?

    - by Malvolio
    I'm writing a system that is deployed in several places and each site needs its own configurations and settings. A "configuration" is a named value that is necessary to a particular site (e.g., the database URL, S3 bucket name); every configuration is necessary, there is not usually a default, and it's typically string-valued. A setting is a named value but it just tweaks the behavior of the system; it's often numeric or Boolean, and there's usually some default. So far, I've been using property files or thing like them, but it's a terrible solution. Several times, a developer has added a requirement for a configuration but not added the value to file for the live configuration, so the new release passed all the tests, then failed when released to live. Better, of course, for every file to be compiled — so if there's a missing configuration, or one of the wrong type, it won't get past the compiler — and inject the site-specific class into the build for each site. As a bones, a Scala file can easy model more complex values, especially lists, but also maps and tuples. The downside is, the files are sometimes maintained by people who aren't developers, so it has to be pretty self-explanatory, which was the advantage of property files. (Someone explain XML configurations to me: all the complexity of a compilable file but the run-time risk of a property file.) What I'm looking for is an easy pattern for defining a group required names and allowable values. Any suggestions?

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  • The perfect web UI framework (with Microsoft stack?) - architecture question?

    - by Igorek
    I'm looking for suggestions for the following issue, and I realize there is really not going to be a perfect answer to my question: I have a UI built in WinForms.NET (v4.0 framework) with WCF back-end and EF4 model objects, that I am looking to port to the web. UI is not huge and is not super complex and is structured well. But it is not a super simple system either. I am looking to pick a technology stack for the web-frontend that will target desktop & partially mobile platforms, provide a good development platform to build on, and facilitate code reuse across UI and back-end tiers... I would rather avoid: custom coding of UI-centric scripts, because they are hard to debug, non-compiled, usually a maintenance nightmare, almost always start to contain business logic, and duplicate some of the logic that back-end tiers have (especially validation) custom-coding for Desktop Web and Mobile Web UI's separately (although I realize that mobile web UI will likely contain fewer of data-entry screens and more reporting screens) non-.NET technology stacks I would love to: target the reporting capabilities of the system toward mobile web browsers not have to write a single line of script (javascript, jquery, etc.) utilize a good collection of controls that produces an elegant UI use .NET for everything The way I see it right now, I need to re-write this app in Silverlight, utilize a 3rd party UI framework like Telerik, and re-do the reports UI again for mobile platforms separately. However, I'm rather concerned about the shelf-life of Silverlight and the needed to deploy a different architecture to deal with mobile platform. Is there an ASP.NET/MVC/Ajax architecture/framework/library that would allow me to get at the power of .NET and without painful (imho) client-side scripting, while providing a decent user experience Thank you

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  • Best practice to create WPF wrapper application displaying screens on demand.

    - by Robbie
    Context: I'm developing a WPF application which will contain a lot of different "screens". Each screen contains a which on its turn contains all the visual elements. Some elements trigger events (e.g., checkboxes), a screen has individual resources, etc. The main application is "wrapper" around these screens: it contains a menubar, toolbar, statusbar and alike (in a DockPanel) and space to display one screen. Through the menubar, the user can choose which screen he wants to display. Goal: I want to dynamically load & display & (event)handle one screen in the space in the main application. I don't want to copy & paste all the "wrapper" stuff in all the different screens. And As I have many complex screens (around 300 - luckily auto-generated), I don't want to load all of them at the start of the application, but only upon request. Question: What do you recommend as the best way to realize this? What kind of things should I use and investigate: Pages or windows or User Control for the screens? Does this affect the event handling?

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  • How to (unit-)test data intensive PL/SQL application

    - by doom2.wad
    Our team is willing to unit-test a new code written under a running project extending an existing huge Oracle system. The system is written solely in PL/SQL, consists of thousands of tables, hundreds of stored procedures packages, mostly getting data from tables and/or inserting/updating other data. Our extension is not an exception. Most functions return data from a quite complex SELECT statementa over many mutually bound tables (with a little added logic before returning them) or make transformation from one complicated data structure to another (complicated in another way). What is the best approach to unit-test such code? There are no unit tests for existing code base. To make things worse, only packages, triggers and views are source-controlled, table structures (including "alter table" stuff and necessary data transformations are deployed via channel other than version control). There is no way to change this within our project's scope. Maintaining testing data set seems to be impossible since there is new code deployed to the production environment on weekly basis, usually without prior notice, often changing data structure (add a column here, remove one there). I'd be glad for any suggestion or reference to help us. Some team members tend to be tired by figuring out how to even start for our experience with unit-testing does not cover PL/SQL data intensive legacy systems (only those "from-the-book" greenfield Java projects).

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  • How to change the date/time in Python for all modules?

    - by Felix Schwarz
    When I write with business logic, my code often depends on the current time. For example the algorithm which looks at each unfinished order and checks if an invoice should be sent (which depends on the no of days since the job was ended). In these cases creating an invoice is not triggered by an explicit user action but by a background job. Now this creates a problem for me when it comes to testing: I can test invoice creation itself easily However it is hard to create an order in a test and check that the background job identifies the correct orders at the correct time. So far I found two solutions: In the test setup, calculate the job dates relative to the current date. Downside: The code becomes quite complicated as there are no explicit dates written anymore. Sometimes the business logic is pretty complex for edge cases so it becomes hard to debug due to all these relative dates. I have my own date/time accessor functions which I use throughout my code. In the test I just set a current date and all modules get this date. So I can simulate an order creation in February and check that the invoice is created in April easily. Downside: 3rd party modules do not use this mechanism so it's really hard to integrate+test these. The second approach was way more successful to me after all. Therefore I'm looking for a way to set the time Python's datetime+time modules return. Setting the date is usually enough, I don't need to set the current hour or second (even though this would be nice). Is there such a utility? Is there an (internal) Python API that I can use?

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  • MS Acess SQL - where clause to get year from date based on the year - data located in MS access form

    - by primus285
    OK, back again. I have a problem getting a drop down list to populate based on information in two fields. I have got the SQL correct as to Select just one year if I put DateValue('01/01/2001') in both places, but I am trying now to get it to grab the year data from the MS access form - another drop down named "cboYear". I'd hate to have to do something in VB, unless necessary. so far I have gotten this to pull up something (its always incorrect) SELECT DISTINCT Database_New.ASEC FROM Database_New WHERE Database_New.Date>=DateValue('01/01/' & [cboYear]) And Database_New.Date<=DateValue('12/31/' & [cboYear]); and SELECT DISTINCT Database_New.ASEC FROM Database_New WHERE Database_New.Date>=DateValue('01/01/' + [cboYear]) And Database_New.Date<=DateValue('12/31/' + [cboYear]); SELECT DISTINCT Database_New.ASEC FROM Database_New WHERE Database_New.Date>=DateValue('01/01/' AND [cboYear]) And Database_New.Date<=DateValue('12/31/' AND [cboYear]); both give errors saying that it is too complex to compute. Its probably something simple, but where do I go from here?

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  • Why are compilers so stupid?

    - by martinus
    I always wonder why compilers can't figure out simple things that are obvious to the human eye. They do lots of simple optimizations, but never something even a little bit complex. For example, this code takes about 6 seconds on my computer to print the value zero (using java 1.6): int x = 0; for (int i = 0; i < 100 * 1000 * 1000 * 1000; ++i) { x += x + x + x + x + x; } System.out.println(x); It is totally obvious that x is never changed so no matter how often you add 0 to itself it stays zero. So the compiler could in theory replace this with System.out.println(0). Or even better, this takes 23 seconds: public int slow() { String s = "x"; for (int i = 0; i < 100000; ++i) { s += "x"; } return 10; } First the compiler could notice that I am actually creating a string s of 100000 "x" so it could automatically use s StringBuilder instead, or even better directly replace it with the resulting string as it is always the same. Second, It does not recognize that I do not actually use the string at all, so the whole loop could be discarded! Why, after so much manpower is going into fast compilers, are they still so relatively dumb? EDIT: Of course these are stupid examples that should never be used anywhere. But whenever I have to rewrite a beautiful and very readable code into something unreadable so that the compiler is happy and produces fast code, I wonder why compilers or some other automated tool can't do this work for me.

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  • Is there a better way to write this LINQ query?

    - by Raj Aththanayake
    Hi Is there a better simplified way to write this query. My logic is if collection contains customer ids and countrycodes, do the query ordey by customer id ascending. If there are no contain id in CustIDs then do the order by customer name. Is there a better way to write this query? I'm not really familiar with complex lambdas. var custIdResult = (from Customer c in CustomerCollection where (c.CustomerID.ToLower().Contains(param.ToLower()) && (countryCodeFilters.Any(item => item.Equals(c.CountryCode))) ) select c).ToList(); if (custIdResult.Count > 0) { return from Customer c in custIdResult where ( c.CustomerName.ToLower().Contains(param.ToLower()) && countryCodeFilters.Any(item => item.Equals(c.CountryCode))) orderby c.CustomerID ascending select c; } else { return from Customer c in CustomerCollection where (c.CustomerName.ToLower().Contains(param.ToLower()) && countryCodeFilters.Any(item => item.Equals(c.CountryCode))) orderby c.CustomerName descending select c; }

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  • jQuery Accordian

    - by Fuego DeBassi
    Just wondering if anyone can provide some basic advice on an accordion I'm trying to simplify. Got a working version, but it seems way overly complex. Here is my new JS. $(document).ready(function() { $("#themes li ul").hide(); $("#themes li").hover(function() { $("ul").show(); }, function() { $("li ul").hide(); }); The markup looks like this: <ul> <li>Tier 1 <ul> <li>Tier 2</li> <li>Tier 2</li> </ul> </li> <li>Tier 1 <ul> <li>Tier 2</li> <li>Tier 2</li> </ul> </li> </ul> My script works alright. But it shows all of the child ul's when any parent li is hovered, and it hide's all the child ul's when unhovered. Just not sure how I can get it to A.) Only .show the li ul when that specific li is hovered. And B.) Hide the show'n li ul only when another one is hovered (not itself). Example + explanation would be especially helpful! Thanks!!

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  • Why is partial specialziation of a nested class template allowed, while complete isn't?

    - by drhirsch
    template<int x> struct A { template<int y> struct B {};. template<int y, int unused> struct C {}; }; template<int x> template<> struct A<x>::B<x> {}; // error: enclosing class templates are not explicitly specialized template<int x> template<int unused> struct A<x>::C<x, unused> {}; // ok So why is the explicit specialization of a inner, nested class (or function) not allowed, if the outer class isn't specialiced too? Strange enough, I can work around this behaviour if I only partially specialize the inner class with simply adding a dummy template parameter. Makes things uglier and more complex, but it works. Note: I need this feature for recursive templates of the inner class for a set of the outer class. To make things even more complicate, in reality I only need a template function instead of the inner class. But partial specialization of functions is generally disallowed somewhere else in the standard ^^

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  • IPad SQLite Push and Pull Data from external MS SQL Server DB

    - by MattyD
    This carries on from my previous post (http://stackoverflow.com/questions/4182664/ipad-app-pull-and-push-relational-data). My plan is that when the ipad application starts I am going to pull data (config data i.e. Departments, Types etc etc relational data that is used across the system) from a webhosted MS SQL Server DB via a webservice and populate it into an SQL Lite DB on the IPad. Then when I load a listing I will pull the data over the line again via a webservice and populate it into the SQL Lite db on the ipad (than just run select commands to populate the listing). My questions are: 1. What is the most efficient way to transfer data across the line via the web? Everyone seems to do it a different way. My idea is that I will have a webService for each type of data pull (e.g. RetrieveContactListing) that will query the db and than convert that data into "something" to send across the line. My question really is what is the "something" that it should be converting into? 2. Everyone talks about odata services. Is this suited for applications where complex read and writes are needed? Ive created a simple iphone app before that talked to an sql server db (i just sent my own structured xml across the line) but now with this app the data calls are going to be a lot larger so efficiency is key.

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  • passing data from a servlet to javascript code in an Ajax application ?

    - by A.S al-shammari
    I have a simple jsp/servlet application and I want to add AJAX feature to this app. I use JQuery , but it doesn't matter what javascript framework I use. This is my code: <script type="text/javascript"> function callbackFunction(data){ $('#content').html(data); } $('document').ready(function(){ $('#x').click(function() { $.post('/ajax_2/servlet',callbackFunction) }); }); </script> <body> <a href="#" id="x">Increase it</a> <div id="content"></div> </body> </html> Servlet HttpSession session = request.getSession(); Integer myInteger = (Integer)session.getAttribute("myInteger"); if(myInteger == null) myInteger = new Integer(0); else myInteger = new Integer(myInteger+1); session.setAttribute("myInteger", myInteger); response.getWriter().println(myInteger); The Question: I use out.print to transfer data from a servlet to javascript code (ajax code) , but If I have a complex structure such as Vector of Object or something like this , what is the best way to transfer the data? what about an XML file , JSON ? Is there any special jsp/servlets library to transfer data from a servlet to ajax application ? How can I parse this data in callbackFunction ?

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  • How to change XmlSchemaElement.SchemaType (or: difference between SchemaType and ElementSchemaType)

    - by Gregor
    Hey, I'm working on a XML Editor which gets all his information from the corresponding XSD file. To work with the XSD files I use the System.Xml.Schema Namespace (XmlSchema*). Because of an 'xsi:type' attribute in the XML I've to change the XmlSchemaType of an XmlSchemaElement. Until now I use in my code the 'ElementSchemaType' property of 'XmlSchemaElement'. The nice thing about it: it's read only. There is also in 'XmlSchemaElement' an 'SchemaType' property which is not read only, but always null (yes, XmlSchema and XmlSchemaSet are compiled). So how can I change the type of the 'XmlSchemaElement'? Or, also the same question: What is the diffrence between this two porperties? Some technical data: C#, .NET 3.5 The MSDN documentation is nearly the same for both: SchemaType Documentation: Gets or sets the type of the element. This can either be a complex type or a simple type. ElementSchemaType Documentation: Gets an XmlSchemaType object representing the type of the element based on the SchemaType or SchemaTypeName values of the element.

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  • Graphing the pitch (frequency) of a sound

    - by Coronatus
    I want to plot the pitch of a sound into a graph. Currently I can plot the amplitude. The graph below is created by the data returned by getUnscaledAmplitude(): AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(new BufferedInputStream(new FileInputStream(file))); byte[] bytes = new byte[(int) (audioInputStream.getFrameLength()) * (audioInputStream.getFormat().getFrameSize())]; audioInputStream.read(bytes); // Get amplitude values for each audio channel in an array. graphData = type.getUnscaledAmplitude(bytes, this); public int[][] getUnscaledAmplitude(byte[] eightBitByteArray, AudioInfo audioInfo) { int[][] toReturn = new int[audioInfo.getNumberOfChannels()][eightBitByteArray.length / (2 * audioInfo. getNumberOfChannels())]; int index = 0; for (int audioByte = 0; audioByte < eightBitByteArray.length;) { for (int channel = 0; channel < audioInfo.getNumberOfChannels(); channel++) { // Do the byte to sample conversion. int low = (int) eightBitByteArray[audioByte]; audioByte++; int high = (int) eightBitByteArray[audioByte]; audioByte++; int sample = (high << 8) + (low & 0x00ff); if (sample < audioInfo.sampleMin) { audioInfo.sampleMin = sample; } else if (sample > audioInfo.sampleMax) { audioInfo.sampleMax = sample; } toReturn[channel][index] = sample; } index++; } return toReturn; } But I need to show the audio's pitch, not amplitude. Fast Fourier transform appears to get the pitch, but it needs to know more variables than the raw bytes I have, and is very complex and mathematical. Is there a way I can do this?

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  • about c# OBJECTS and the Possibilties it has.

    - by user527825
    As a novice programmer and i always wonder about c# capabilities.i know it is still early to judge that but all i want to know is can c# do complex stuffs or something outside windows OS. 1- I think c# is a proprietary language (i don't know if i said that right) meaning you can't do it outside visual studio or windows. 2-also you cant create your own controller(called object right?) like you are forced to use these available in toolbox and their properties and methods. 3-can c# be used with openGL API or DirectX API . 4-Finally it always bothers me when i think i start doing things in visual studio, i know it sounds arrogant to say but sometimes i feel that i don't like to be forced to use something even if its helpful, like i feel (do i have the right to feel?) that i want to do all things by myself? don't laugh i just feel that this will give me a better understanding. 5- is visual c# is like using MaxScript inside 3ds max in that c# is exclusive to do windows and forms and components that are windows related and maxscript is only for 3d editing and manipulation for various things in the software. If it is too difficult for a beginner i hope you don't answer the fourth question as i don't have enough motivation and i want to keep the little i have. thank you for your time. Note: 1-sorry for my English, i am self taught and never used the language with native speakers so expect so errors. 2-i have a lot of questions regarding many things, what is the daily ratio you think for asking (number of questions) that would not bother the admins of the site and the members here. thank you for your time.

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  • What database strategy to choose for a large web application

    - by Snoopy
    I have to rewrite a large database application, running on 32 servers. The hardware is up to date, each machine has two quad core Xeon and 32 GByte RAM. The database is multi-tenant, each customer has his own file, around 5 to 10 GByte each. I run around 50 databases on this hardware. The app is open to the web, so I have no control on the load. There are no really complex queries, so SQL is not required if there is a better solution. The databases get updated via FTP every day at midnight. The database is read-only. C# is my favourite language and I want to use ASP.NET MVC. I thought about the following options: Use two big SQL servers running SQL Server 2012 to serve the 32 servers with data. On the 32 servers running IIS hosting providing REST services. Denormalize the database and use Redis on each webserver. Use booksleeve as a Redis client. Use a combination of SQL Server and Redis Use SQL Server 2012 together with Hadoop Use Hadoop without SQL Server What is the best way for a read-only database, to get the best performance without loosing maintainability? Does Map-Reduce make sense at all in such a scenario? The reason for the rewrite is, the old app written in C++ with ISAM technology is too slow, the interfaces are old fashioned and not nice to use from an website, especially when using ajax. The app uses a relational datamodel with many tables, but it is possible to write one accerlerator table where all queries can be performed on, and all other information from the other tables are possible by a simple key lookup.

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  • Need Help finding an appropriate task asignment algoritm for a collage project involving coordinatin

    - by Trif Mircea
    Hello. I am a long time lurker here and have found over time many answers regarding jquery and web development topics so I decided to ask a question of my own. This time I have to create a c++ project for collage which should help manage the workflow of a company providing all kinds of services through in the field teams. The ideas I have so far are: client-server application; the server is a dispatcher where all the orders from clients get and the clients are mobile devices (PDAs) each team in the field having one a order from a client is a task. Each task is made up of a series of subtasks. You have a database with estimations on how long a task should take to complete you also know what tasks or subtasks each team on the field can perform based on what kind of specialists made up the team (not going to complicate the problem by adding needed materials, it is considered that if a member of a team can perform a subtask he has the stuff needed) Now knowing these factors, what would a good task assignment algorithm be? The criteria is: how many tasks can a team do, how many tasks they have in the queue, it could also be location, how far away are they from the place but I don't think I can implement that.. It needs to be efficient and also to adapt quickly is the human dispatcher manually assigns a task. Any help or leads would be really appreciated. Also I'm not 100% sure in the idea so if you have another way you would go about creating such an application please share, even if it just a quick outline. I have to write a theoretical part too so even if the ideas are far more complex that what i outlined that would be ok ; I'd write those and implement what I can.

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  • How do I use .htaccess to redirect to a URL containing HTTP_HOST?

    - by Jon Cram
    Problem I need to redirect some short convenience URLs to longer actual URLs. The site in question uses a set of subdomains to identify a set of development or live versions. I would like the URL to which certain requests are redirected to include the HTTP_HOST such that I don't have to create a custom .htaccess file for each host. Host-specific Example (snipped from .htaccess file) Redirect /terms http://support.dev01.example.com/articles/terms/ This example works fine for the development version running at dev01.example.com. If I use the same line in the main .htaccess file for the development version running under dev02.example.com I'd end up being redirected to the wrong place. Ideal rule (not sure of the correct syntax) Redirect /terms http://support.{HTTP_HOST}/articles/terms/ This rule does not work and merely serves as an example of what I'd like to achieve. I could then use the exact same rule under many different hosts and get the correct result. Answers? Can this be done with mod_alias or does it require the more complex mod_rewrite? How can this be achieved using mod_alias or mod_rewrite? I'd prefer a mod_alias solution if possible. Clarifications I'm not staying on the same server. I'd like: http://example.com/terms/ - http://support.example.com/articles/terms/ https://secure.example.com/terms/ - http://support.example.com/articles/terms/ http://dev.example.com/terms/ - http://support.dev.example.com/articles/terms/ https://secure.dev.example.com/terms/ - http://support.dev.example.com/articles/terms/ I'd like to be able to use the same rule in the .htaccess file on both example.com and dev.example.com. In this situation I'd need to be able to refer to the HTTP_HOST as a variable rather than specifying it literally in the URL to which requests are redirected. I'll investigate the HTTP_HOST parameter as suggested but was hoping for a working example.

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  • What file format can I use to output a formatted text file straight from a program without having the markup be too complicated?

    - by Matt
    Premise: I am parsing a file that is quite nearly XML, but not quite. From this file I would like to extract data and output in a file that a user could open up in some program and read. To make the data reasonable, I would almost certainly need to format the text. In case it matters, I will probably be using Java to write the program. Problem: I cannot find a file format that supports formatting without having terribly complex rules and encoding problems. Attempts: I looked into a basic .txt extension first, but it does not have enough formatting advantage. I then tried a .rtf extension, but the rules for outputting text seem to be terribly complicated. It was then suggested that I used XML, but I do not understand how this file would be viewed. This appears to be probably the best solution, but I don't understand much about it. Perhaps somebody could shed some light here. In Other Words: Could somebody suggest and easy to use file format and/or shed some light on how to use XML for text formatting and viewing?

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