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• What to keep in mind when creating your own custom web services API?

  - by John Conde

  I have created a website which allows users to sign up for, and use, an online service. To help promote the website we will be have resellers who will be offering their own branded services through us. The initial plan is to allow resellers to place registration, login, and lost password forms on their own website and use an API created by us to handle these requests. I have begun outlining how I expect the API to work (and starting documenting it as well) and I want to make sure I get it right, or as close to right, as I can from the beginning as I know once you have declared a public API you want to avoid changing that API at all costs. So far I have decided: To have the user pass their account credentials with each request To require SSL for all requests What else should I be keeping in mind?

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• Embed external images for use in HTML canvas?

  - by Philipp Lenssen

  I'm using JavaScript to load an image into my Canvas element in Firefox. This works fine for local images, but throws a security exception for external images. Is there any way to avoid this security exception, one that does not involve my server having to act as proxy to load the image locally (because that would stress my server)? PS: The current code is similar to this: var img = new Image(); var contextSource = canvasSource.getContext('2d'); contextSource.drawImage(img, 0, 0); // get image data to do stuff with pixels var imageDataSource = contextSource.getImageData(0, 0, width - 1, height - 1);

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• What are some things I should watch out for before hiring a freelance programmer

  - by Luke101

  I am looking to hire a freelancer for a big web application. The budget for this project is a little over $20,000. The programmer will develop in asp.net MVC C#. Are there any usual things I should pay attention to or watch out for. i really don't want to hire the freelancer and when he/she is done with the project it is not what i expect. I have heard horror stories where the programmer delivered a fantastic product but the code was not commented and parts of the software was hidden behind DLLs. Is there anyway to avoid situations like this? I am sure I cannot think of every possible scenario when i write the project description. Also, is it advisable to hire a lawyer to write the contract?

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• How to specify a different column for a @Inheritance JPA annotation

  - by Cue

  @Entity @Inheritance(strategy = InheritanceType.JOINED) public class Foo @Entity @Inheritance(strategy = InheritanceType.JOINED) public class BarFoo extends Foo mysql> desc foo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ mysql> desc barfoo; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | | foo_id | int | | bar_id | int | +---------------+-------------+ mysql> desc bar; +---------------+-------------+ | Field | Type | +---------------+-------------+ | id | int | +---------------+-------------+ Is it possible to specify column barfo.foo_id as the joined column? Are you allowed to specify barfoo.id as BarFoo's @Id since you are overriding the getter/seeter of class Foo? I understand the schematics behind this relationship (or at least I think I do) and I'm ok with them. The reason I want an explicit id field for BarFoo is exactly because I want to avoid using a joined key (foo _id, bar _id) when querying for BarFoo(s) or when used in a "stronger" constraint. (as Ruben put it)

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• Incremement Page Hit Count in Django

  - by Andrew C

  I have a table with an IntegerField (hit_count), and when a page is visited (ie. http://site/page/3) I want record id 3 'hit_count' column in the database to increment by 1. The query should be like: update table set hit_count = hit_count + 1 where id=3 Can I do this with the standard Django Model conventions? Or should I just write the query by hand? I'm starting a new project, so I am trying to avoid hacks. We'll see how long this lasts! Thanks!

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• Any ideas for developing a Risc Processor friendly string allocator?

  - by Richard Fabian

  I'm working on some tools to enable high throughput data-oriented development, and one thing that I've not got an immediate answer for is how you go about allocating strings quickly. On risc processors you've got another problem of implementation that the CPU doesn't like branching, which is what I'm trying to minimise or avoid. Also, cache coherence is important on most CPUs, so that's gotta be influential in the design too. So, how would you go about reducing the overhead for a generic string allocator? Sometimes it's easier to solve a more explicit problem, so any ideas for string sizes of 5-30?

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• When to pass by value?

  - by Dervin Thunk

  Dear all. I was wondering if there are examples of situations where you would purposefully pass an argument by value in C. Let me rephrase. When do you purposefully use C's pass-by-value for large objects? Or, when do you care that the object argument is fully copied in a local variable? EDIT: Now that I think about it, if you can avoid pointers, then do. Nowadays, "deep" copying is possible for mostly everything in small apps, and shallow copying is more prone to pointer bugs. Maybe.

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• How to handle model state errors in ajax-invoked controller action that returns a PartialView

  - by Robert Koritnik

  I have a POST controller action that returns a partial view. Everything seems really easy. but. I load it using $.ajax(), setting type as html. But when my model validation fails I thought I should just throw an error with model state errors. But my reply always returns 500 Server error. How can I report back model state errors without returning Json with whatever result. I would still like to return partial view that I can directly append to some HTML element. Edit I would also like to avoid returning error partial view. This would look like a success on the client. Having the client parse the result to see whether it's an actual success is prone to errors. Designers may change the partial view output and this alone would break the functionality. So I want to throw an exception, but with the correct error message returned to the ajax client.

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• Deadlock between select and truncate (postgresql)

  - by valodzka

  Table output_values_center1 (and some other) inherits output_values. Periodically I truncate table output_values_center1 and load new data (in one transaction). In that time user can request some data and he got error message. Why it ever happens (select query requests only one record) and how to avoid such problem: 2010-05-19 14:43:17 UTC ERROR: deadlock detected 2010-05-19 14:43:17 UTC DETAIL: Process 25972 waits for AccessShareLock on relation 2495092 of database 16385; blocked by process 26102. Process 26102 waits for AccessExclusiveLock on relation 2494865 of database 16385; blocked by process 25972. Process 25972: SELECT * FROM "output_values" WHERE ("output_values".id = 122312) LIMIT 1 Process 26102: TRUNCATE TABLE "output_values_center1"

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• Avoiding string copying in Lua

  - by Matt Sheppard

  Say I have a C program which wants to call a very simple Lua function with two strings (let's say two comma separated lists, returning true if the lists intersect at all, false if not). The obvious way to do this is to push them onto the stack with lua_pushstring, which works fine, however, from the doc it looks like lua_pushstring but makes a copy of the string for Lua to work with. That means that to cross over to the Lua function is going to require two string copies which I could avoid by rewriting the Lua function in C. Is there any way to arrange things so that the existing C strings could be reused on the Lua side for the sake of performance (or would the strcpy cost pale into insignificance anyway)? From my investigation so far (my first couple of hours looking seriously at Lua), lite userdata seems like the sort of thing I want, but in the form of a string.

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• Client-side session timeout redirect in ASP.Net

  - by Mercury821

  I want to build a way to automatically redirect users to Timeout.aspx when their session expires due to inactivity. My application uses forms authentication and relies heavily on update panels within the same aspx page for user interaction, so I don't want to simply redirect after a page-level timer expires. For the same reason, I can't use '<meta http-equiv="refresh"/>' What I want to do is create a simple ajax web service with a method called IsSessionTimedOut(), that simply returns a boolean. I will use a javascript timer to periodically call the method, and if it returns true, then redirect to Timeout.aspx. However, I don't want calling this method to reset the session timeout timer, or the session would never time out because of the service call. Is there a clean way to avoid this catch-22? Hopefully there is an easy solution that has so far eluded me.

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• Best approach to create a security environment in Java

  - by Tom Brito

  I need to create a desktop application that will run third party code, and I need to avoid the third party code from export by any way (web, clipboard, file io) informations from the application. Somethig like: public class MyClass { private String protectedData; public void doThirdPartyTask() { String unprotedtedData = unprotect(protectedData); ThirdPartyClass.doTask(unprotectedData); } private String unprotect(String data) { // ... } } class ThirdPartyClass { public static void doTask(String unprotectedData) { // Do task using unprotected data. // Malicious code may try to externalize the data. } } I'm reading about SecurityManager and AccessControler, but I'm still not sure what's the best approach to handle this. What should I read about to do this implementation?

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• Should I use curly brackets or concatenate variables within strings?

  - by mririgo

  Straight forward question: Is there an advantage or disadvantage to concatenating variables within strings or using curly braces instead? Concatenated: $greeting = "Welcome, ".$name."!"; Curly braces: $greeting = "Welcome, {$name}!"; Personally, I've always concatenated my strings because I use UEStudio and it highlights PHP variables a different color when concatenated. However, when the variable is not broken out, it does not. It just makes it easier for my eyes to find PHP variables in long strings, etc. EDIT: People are confusing this about being about SQL. This is not what this question is about. I've updated my examples to avoid confusion.

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• Better algorithm for estimating download time

  - by Scott Smith

  We've all seen the download time running estimate that initially says something like "7 days", but keeps dropping wildly (e.g. "23 hours", "45 minutes", "1 min. 50 sec", etc) with each successive estimation as the chunks are downloaded. To avoid these initial (alarming) estimates, there are techniques one could try like suppressing display of the first n estimates, or waiting for the delta between estimates to drop below some threshold before you start displaying them, but these don't seem like a general, robust solution. There are corner cases involving too few samples, or samples that actually are wildly varying... I think I recall a general solution for this kind of thing in mathematics (statistics?) that reduced or eliminated these wild values. Does anyone know?

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• Is *not* using the asp.net membership provider a bad idea?

  - by EJB

  Is it generally a really bad idea to not use the built-in asp.net membership provider? I've always rolled my own for my asp.net apps (public facing), and really have not had any problems in doing so. It works, and seems to avoid a layer of complexity. My needs are pretty basic: once setup, the user must use email address and password to login, if they forget it, it will be emailed back to them (a new one). After setup there is little that needs to be done to each user account, but I do need to store several extra fields with each user (full name, telephone and a few other fields etc). The number of users that required login credentials are small (usually just the administrator and a few backups), and everyone else uses the site unauthenticated. What are the big advantages that I might be missing out on by skipping the asp.net membership provider functionality?

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• What are unused/undeclared dependencies in maven ? What to do with them ?

  - by b7kich

  Maven dependency:analyze complains about the dependencies in my project. How does it determine which are unused and which are undeclared ? What should I do about them ? Example: $ mvn dependency:analyze ... [WARNING] Used undeclared dependencies found: [WARNING] org.slf4j:slf4j-api:jar:1.5.0:provided [WARNING] commons-logging:commons-logging:jar:1.1.1:compile [WARNING] commons-dbutils:commons-dbutils:jar:1.1-osgi:provided [WARNING] org.codehaus.jackson:jackson-core-asl:jar:1.6.1:compile ... [WARNING] Unused declared dependencies found: [WARNING] commons-cli:commons-cli:jar:1.0:compile [WARNING] org.mortbay.jetty:servlet-api:jar:2.5-20081211:test [WARNING] org.apache.httpcomponents:httpclient:jar:4.0-alpha4:compile [WARNING] commons-collections:commons-collections:jar:3.2:provided [WARNING] javax.mail:mail:jar:1.4:provided Note: A lot of these dependencies are used in my runtime container and I declared them as provided to avoid having same library on the classpath twice with different versions.

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• Using Timer only once

  - by zaidwaqi

  Hi, I want to use a timer only once, at 1 second after the initialization of my main form. I thought the following would have a message box saying "Hello World" just once, but actually a new message box says "Hello World" every one second. Why so? I had put t.Stop() in the tick event. Also, do I need to dispose the timer somehow to avoid memory leakage? Timer t = new Timer(); t.Interval = 1000; t.Tick += delegate(System.Object o, System.EventArgs e) { MessageBox.Show("Hello World"); t.Stop(); }; t.Start(); Please help and show if there is a better way of doing this? Thanks.

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• Setting the Cursor Position in a Win32 Console Application

  - by Jim Fell

  How can I set the cursor position in a Win32 Console application? Preferably, I would like to avoid making a handle and using the Windows Console Functions. (I spent all morning running down that dark alley; it creates more problems than it solves.) I seem to recall doing this relatively simply when I was in college using stdio, but I can't find any examples of how to do it now. Any thoughts or suggestions would be greatly appreciated. Thanks.

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• Pure virtual destructor in interface

  - by ALOR

  Hello all. Here is my problem. I'm making C++ dll, which extensively relies on instance object exports. So i return my actual instances as a pointers to interface through some exported factory method. Interfaces i use are purely virtual, to avoid linking problame. So i need a pure virtual destructor too, and i implemented one (with empty body, as i googled it). All compiles perfectly well, except... I can't see, if the actual destructors are called or not - because when i added some std::cout << "hello destructor"; i never get to see it. I have some explicit "delete obj", that's not the problem. Am i missing something? Is there another way to delete my object through interface?

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• access custom group

  - by Carlos

  I have my Access 2007 database configured to use "Custom" groups in the navigation pane. I've grouped all my tables in a way that makes sense. However, whenever I update a link table, it loses its grouping. I have not been able to find a way to avoid this. Since it seems to be unavoidable, I'd like to simply have a macro that adds the table back to the right group programatically. I have not found any examples on how to do this. Any suggestions?

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• Negative zero using Crystal Report ToText()

  - by Dan Ward

  Using Crystal Reports 8.5 on Windows Vista or 7, I'm using the ToText function to report a value: totext(Sum ({ap121w7.yrentamt}, {@type1099})*100,"000000000000000000") The result (if yrentamt is 0) is -000000000000000000 The dash (I assume it's a negative sign) is unneccessary and unwanted in my report. Is this a bug, or is there an easy solution? --Note-- I would very much like to avoid the following: if {ap121w7.yrentamt}=0.00 then yrentamt := "000000000000" else yrentamt := totext({ap121w7.yrentamt}*100,"000000000000"); I have about 100 files to fix with multiple formulas per file, and the above solution doesn't seem to work consistently either.

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• Tool for checking source for dependencies on specific Java versions

  - by Gregor

  Is there a quick way (e.g. tool) to detect, from the source (or maybe even from compiled classes), which parts of an application call Java API methods that are only implemented in a specific Java version? (e.g. which parts of my app are Java6-specific) I don't necessarily want to hop through all ClassMismatchErrors and avoid the trial-and-error-method. Let's say I only want to document which parts of an application won't work if they were writte for, e.g., Java6 and I want to run it in a version 5 JDK. Is there something like this? Google did not help this time, nor did I find any solution here (a rare case indeed:)

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• Show friendly message on ASP.NET Ajax error

  - by balexandre

  You all know how annoying is this: I do have a log system and the correct error is well explicit there, but I want to give a better message to the user. I keep trying several ways but I'm using Telerik components and well jQuery and I ended up using both ASP.NET Ajax methods and jQuery, so I use function pageLoad() { try { var manager = Sys.WebForms.PageRequestManager.getInstance(); manager.add_endRequest(endRequest); manager.add_beginRequest(OnBeginRequest); manager } catch (err) { alert(err); } } as well $(document).ready(function() { ... } that alert(err) is never fired even upon OnClick events what's the best approach to avoid this message errors and provide a cleaner way? all this happens in <asp:UpdatePanel> as I use that when I didn't know better (3 years ago!) and I really don't want to mess up and build all again from scratch :( Any help is greatly appreciated Updated with more error windows after volpav solution

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• Modern Web Development + General question

  - by ritu

  I have been given a nasty wake up a while ago when I discovered that my 10 years of experience was really equivalent of about 4 (got trapped in a big company doing the same thing over and over without realizing it) and is now paying a huge price. Question 1: I did servlets/JSP programming back in the day (2001-2003). Since then there have been libraries like GWT, YUI, etc. Is JSP still the preferred way of building web apps using Java? Question 2: Because I enjoyed what I was doing and needed to pay the bills, I didn't realize that the ground below me has shifted. How do avoid this in the future? My years of C system programming doesn't seem to matter a lot now to the young guys who talk about design patterns.

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• How can I set the main theme-font dynamically, in WordPress

  - by windyjonas

  I have created a theme where I already have a custom options page where I let the user set text for footer, twitter user and some other things and that works well. Now i'd like to add the functionality of letting the user select which font that should be used for content on the site. How can i accomplish this? I can probably create a php file that outputs something like: <style type="text/css"> body{ font-family: <?php echo get_option('my-font');?>; } </style> and include that file in header.php, but that means that I have to hit php for every request for this css and I want to avoid that if posssible.

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