reverse thinking - Page 431

Webservice for uploading data: security considerations

- by Philip Daubmeier

Hi everyone! Im not sure about what authentification method I should use for my webservice. I've searched on SO, and found nothing that helped me. Preliminary Im building an application that uploads data from a local database to a server (running my webservice), where all records are merged and stored in a central database. I am currently binary serializing a DataTable, that holds a small fragment of the local database, where all uninteresting stuff is already filtered out. The byte[] (serialized DataTable), together with the userid and a hash of the users password is then uploaded to the webservice via SOAP. The application together with the webservice already work exactly like intended. The Problem The issue I am thinking about is now: What is if someone just sniffs the network traffic, 'steals' the users id and password hash to send his own SOAP message with modified data that corrupts my database? Options The approaches to solving that problem, I already thought of, are: Using ssl + certificates for establishing the connection: I dont really want to use ssl, I would prefer a simpler solution. After all, every information that is transfered to the webservice can be seen on the website later on. What I want to say is: there is no secret/financial/business-critical information, that has to be hidden. I think ssl would be sort of an overkill for that task. Encrypting the byte[]: I think that would be a performance killer, considering that the goal of the excercise was simply to authenticate the user. Hashing the users password together with the data: I kind of like the idea: Creating a checksum from the data, concatenating that checksum with the password-hash and hashing this whole thing again. That would assure the data was sent from this specific user, and the data wasnt modified. The actual question So, what do you think is the best approach in terms of meeting the following requirements? Rather simple solution (As it doesnt have to be super secure; no secret/business-critical information transfered) Easily implementable retrospectively (Dont want to write it all again :) ) Doesnt impact to much on performance What do you think of my prefered solution, the last one in the list above? Is there any alternative solution I didnt mention, that would fit better? You dont have to answer every question in detail. Just push me in the right direction. I very much appreciate every well-grounded opinion. Thanks in advance!

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How can I represent a line of music notes in a way that allows fast insertion at any index?

- by chairbender

For "fun", and to learn functional programming, I'm developing a program in Clojure that does algorithmic composition using ideas from this theory of music called "Westergaardian Theory". It generates lines of music (where a line is just a single staff consisting of a sequence of notes, each with pitches and durations). It basically works like this: Start with a line consisting of three notes (the specifics of how these are chosen are not important). Randomly perform one of several "operations" on this line. The operation picks randomly from all pairs of adjacent notes that meet a certain criteria (for each pair, the criteria only depends on the pair and is independent of the other notes in the line). It inserts 1 or several notes (depending on the operation) between the chosen pair. Each operation has its own unique criteria. Continue randomly performing these operations on the line until the line is the desired length. The issue I've run into is that my implementation of this is quite slow, and I suspect it could be made faster. I'm new to Clojure and functional programming in general (though I'm experienced with OO), so I'm hoping someone with more experience can point out if I'm not thinking in a functional paradigm or missing out on some FP technique. My current implementation is that each line is a vector containing maps. Each map has a :note and a :dur. :note's value is a keyword representing a musical note like :A4 or :C#3. :dur's value is a fraction, representing the duration of the note (1 is a whole note, 1/4 is a quarter note, etc...). So, for example, a line representing the C major scale starting on C3 would look like this: [ {:note :C3 :dur 1} {:note :D3 :dur 1} {:note :E3 :dur 1} {:note :F3 :dur 1} {:note :G3 :dur 1} {:note :A4 :dur 1} {:note :B4 :dur 1} ] This is a problematic representation because there's not really a quick way to insert into an arbitrary index of a vector. But insertion is the most frequently performed operation on these lines. My current terrible function for inserting notes into a line basically splits the vector using subvec at the point of insertion, uses conj to join the first part + notes + last part, then uses flatten and vec to make them all be in a one-dimensional vector. For example if I want to insert C3 and D3 into the the C major scale at index 3 (where the F3 is), it would do this (I'll use the note name in place of the :note and :dur maps): (conj [C3 D3 E3] [C3 D3] [F3 G3 A4 B4]), which creates [C3 D3 E3 [C3 D3] [F3 G3 A4 B4]] (vec (flatten previous-vector)) which gives [C3 D3 E3 C3 D3 F3 G3 A4 B4] The run time of that is O(n), AFAIK. I'm looking for a way to make this insertion faster. I've searched for information on Clojure data structures that have fast insertion but haven't found anything that would work. I found "finger trees" but they only allow fast insertion at the start or end of the list. Edit: I split this into two questions. The other part is here.

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PHP problems when transfering code from Windows to OS X

- by Makka95

I have recently bought a new MacBook Pro. Before I had my MacBook Pro I was working on a website on my desktop computer. And now I want to transfer this code to my new MacBook Pro. The problem is that when I transfered the code (I put it on Dropbox and simply downloaded it on my MacBook Pro) I started to see lots of error messages in my PHP code. The error message I”m receiving is: Warning: Cannot modify header information - headers already sent by (output started at /some/file.php:1) in /some/file.php on line 23 I have done some research on this and it seems that this error is most frequently caused by a new line, simple whitespace or any output before the <?php sign. I have looked through all the places where I have cookies that are being sent in the HTTP request and also where I'm using the header() function. I haven’t detected any output or whitespace that possibly could interfere and cause this problem. Noteworthy is that the error always says that the output is started at line 1. Which got me thinking if there is some kind of coding differences in the way that the Mac OS X and Windows operating systems handle new lines or white spaces? Or could the Dropbox transfer messed something up? The code on one of the sites(login.php) which produces the error: <?php include "mysql_database.php"; login(); $id = $_SESSION['Loggedin']; setcookie("login", $id, (time()+60*60*24*30)); header('Location: ' . $_SERVER['HTTP_REFERER']); ?> login function: function login() { $connection = connecttodatabase(); $pass = ""; $user = ""; $query = ""; if (isset($_POST['user']) && $_POST['user'] != null) { $user = $_POST['user']; if (isset($_POST['pass']) && $_POST['pass'] != null) { $pass = md5($_POST['pass']); $query = "SELECT ID FROM Anvandare WHERE Nickname='$user' AND Password ='$pass'"; } } if ($query != "") { $id = $connection->query($query); $id = mysqli_fetch_assoc($id); $id = $id['ID']; $_SESSION['Loggedin'] = $id; } closeconnection($connection); } Complete error: Warning: Cannot modify header information - headers already sent by (output started at /Users/name/GitHub/website/login.php:1) in /Users/namn/GitHub/website/login.php on line 9

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Sort a list of pointers.

- by YuppieNetworking

Hello all, Once again I find myself failing at some really simple task in C++. Sometimes I wish I could de-learn all I know from OO in java, since my problems usually start by thinking like Java. Anyways, I have a std::list<BaseObject*> that I want to sort. Let's say that BaseObject is: class BaseObject { protected: int id; public: BaseObject(int i) : id(i) {}; virtual ~BaseObject() {}; }; I can sort the list of pointer to BaseObject with a comparator struct: struct Comparator { bool operator()(const BaseObject* o1, const BaseObject* o2) const { return o1->id < o2->id; } }; And it would look like this: std::list<BaseObject*> mylist; mylist.push_back(new BaseObject(1)); mylist.push_back(new BaseObject(2)); // ... mylist.sort(Comparator()); // intentionally omitted deletes and exception handling Until here, everything is a-ok. However, I introduced some derived classes: class Child : public BaseObject { protected: int var; public: Child(int id1, int n) : BaseObject(id1), var(n) {}; virtual ~Child() {}; }; class GrandChild : public Child { public: GrandChild(int id1, int n) : Child(id1,n) {}; virtual ~GrandChild() {}; }; So now I would like to sort following the following rules: For any Child object c and BaseObject b, b<c To compare BaseObject objects, use its ids, as before. To compare Child objects, compare its vars. If they are equal, fallback to rule 2. GrandChild objects should fallback to the Child behavior (rule 3). I initially thought that I could probably do some casts in Comparator. However, this casts away constness. Then I thought that probably I could compare typeids, but then everything looked messy and it is not even correct. How could I implement this sort, still using list<BaseObject*>::sort ? Thank you

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C# 'could not found' existing method

- by shybovycha

Greetings! I've been fooling around (a bit) with C# and its assemblies. And so i've found such an interesting feature as dynamic loading assemblies and invoking its class members. A bit of google and here i am, writing some kind of 'assembly explorer'. (i've used some portions of code from here, here and here and none of 'em gave any of expected results). But i've found a small bug: when i tried to invoke class method from assembly i've loaded, application raised MissingMethod exception. I'm sure DLL i'm loading contains class and method i'm tryin' to invoke (my app ensures me as well as RedGate's .NET Reflector): The main application code seems to be okay and i start thinking if i was wrong with my DLL... Ah, and i've put both of projects into one solution, but i don't think it may cause any troubles. And yes, DLL project has 'class library' target while the main application one has 'console applcation' target. So, the question is: what's wrong with 'em? Here are some source code: DLL source: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ClassLibrary1 { public class Class1 { public void Main() { System.Console.WriteLine("Hello, World!"); } } } Main application source: using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Reflection; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { Assembly asm = Assembly.LoadFrom(@"a\long\long\path\ClassLibrary1.dll"); try { foreach (Type t in asm.GetTypes()) { if (t.IsClass == true && t.FullName.EndsWith(".Class1")) { object obj = Activator.CreateInstance(t); object res = t.InvokeMember("Main", BindingFlags.Default | BindingFlags.InvokeMethod, null, obj, null); // Exception is risen from here } } } catch (Exception e) { System.Console.WriteLine("Error: {0}", e.Message); } System.Console.ReadKey(); } } } UPD: worked for one case - when DLL method takes no arguments: DLL class (also works if method is not static): public class Class1 { public static void Main() { System.Console.WriteLine("Hello, World!"); } } Method invoke code: object res = t.InvokeMember("Main", BindingFlags.Default | BindingFlags.InvokeMethod, null, null, null);

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organizing external libraries and include files

- by stijn

Over the years my projects use more and more external libraries, and the way I did it starts feeling more and more awkward (although, that has to be said, it does work flawlessly). I use VS on Windows, CMake on others, and CodeComposer for targetting DSPs on Windows. Except for the DSPs, both 32bit and 64bit platforms are used. Here's a sample of what I am doing now; note that as shown, the different external libraries themselves are not always organized in the same way. Some have different lib/include/src folders, others have a single src folder. Some came ready-to-use with static and/or shared libraries, others were built /path/to/projects /projectA /projectB /path/to/apis /apiA /src /include /lib /apiB /include /i386/lib /amd64/lib /path/to/otherapis /apiC /src /path/to/sharedlibs /apiA_x86.lib -->some libs were built in all possible configurations /apiA_x86d.lib /apiA_x64.lib /apiA_x64d.lib /apiA_static_x86.lib /apiB.lib -->other libs have just one import library /path/to/dlls -->most of this directory also gets distributed to clients /apiA_x86.dll and it's in the PATH /apiB.dll Each time I add an external libary, I roughly use this process: build it, if needed, for different configurations (release/debug/platform) copy it's static and/or import libraries to 'sharedlibs' copy it's shared libraries to 'dlls' add an environment variable, eg 'API_A_DIR' that points to the root for ApiA, like '/path/to/apis/apiA' create a VS property sheet and a CMake file to state include path and eventually the library name, like include = '$(API_A_DIR)/Include' and lib = apiA.lib add the propertysheet/cmake file to the project needing the library It's especially step 4 and 5 that are bothering me. I am pretty sure I am not the only one facing this problem, and would like see how others deal with this. I was thinking to get rid of the environment variables per library, and use just one 'API_INCLUDE_DIR' and populating it with the include files in an organized way: /path/to/api/include /apiA /apiB /apiC This way I do not need the include path in the propertysheets nor the environment variables. For libs that are only used on windows I even don't need a propertysheet at all as I can use #pragmas to instruct the linker what library to link to. Also in the code it will be more clear what gets included, and no need for wrappers to include files having the same name but are from different libraries: #include <apiA/header.h> #include <apiB/header.h> #include <apiC_version1/header.h> The withdrawal is off course that I have to copy include files, and possibly** introduce duplicates on the filesystem, but that looks like a minor price to pay, doesn't it? ** actually once libraries are built, the only thing I need from them is the include files and thie libs. Since each of those would have a dedicated directory, the original source tree is not needed anymore so can be deleted..

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Planning to create PDF files in Ruby on Rails

- by deau

Hi there, A Ruby on Rails app will have access to a number of images and fonts. The images are components of a visual layout which will be stored separately as a set of rules. The rules specify document dimensions along with which images are used and where. The app needs to take these rules, fetch the images, and generate a PDF that is ready for local printing or emailing. The fonts will also be important. The user needs to customize the layout by inputting text which will be included in the PDF. The PDF must therefore also contain the desired font so that the document renders identically across different machines. Each PDF may have many pages. Each page may have different dimensions but this is not essential. Either way, the ability to manipulate the dimensions and margins given by the PDF is essential. The only thing that needs to be regularly changed is the text. If this is takes too much development then the app can store the layouts in 3rd party PDFs and edit the textual content directly. Eventually though, this will prove too restrictive on the apps intended functionality so I would prefer the app to generate the PDF's itself. I have never worked with PDFs before and, for the most part, I've never had to output anything to the user outside their monitor. A printed medium could require a very different approach to get the best results. If anyone has any advice on how to model the PDF format this it would be really appreciated. The technical aspects of printing such as bleed, resolution and colour have already been factored in to the layouts and images. I am aware that PDF is a proprietary file format and I want to use free or open source software. I have seen a number of Ruby libraries for generating PDF files but because I am new on this scene I have no way to reliably compare them and too little time to implement and test them all. I also have the option of using C to handle this feature and if this is process intensive then that might be preferred. What should I be thinking about and how should I be planning to implement this?

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OpenGL texture shifted somewhat to the left when applied to a quad

- by user308226

I'm a bit new to OpenGL and I've been having a problem with using textures. The texture seems to load fine, but when I run the program, the texture displays shifted a couple pixels to the left, with the section cut off by the shift appearing on the right side. I don't know if the problem here is in the my TGA loader or if it's the way I'm applying the texture to the quad. Here is the loader: #include "texture.h" #include <iostream> GLubyte uncompressedheader[12] = {0,0, 2,0,0,0,0,0,0,0,0,0}; GLubyte compressedheader[12] = {0,0,10,0,0,0,0,0,0,0,0,0}; TGA::TGA() { } //Private loading function called by LoadTGA. Loads uncompressed TGA files //Returns: TRUE on success, FALSE on failure bool TGA::LoadCompressedTGA(char *filename,ifstream &texturestream) { return false; } bool TGA::LoadUncompressedTGA(char *filename,ifstream &texturestream) { cout << "G position status:" << texturestream.tellg() << endl; texturestream.read((char*)header, sizeof(header)); //read 6 bytes into the file to get the tga header width = (GLuint)header[1] * 256 + (GLuint)header[0]; //read and calculate width and save height = (GLuint)header[3] * 256 + (GLuint)header[2]; //read and calculate height and save bpp = (GLuint)header[4]; //read bpp and save cout << bpp << endl; if((width <= 0) || (height <= 0) || ((bpp != 24) && (bpp !=32))) //check to make sure the height, width, and bpp are valid { return false; } if(bpp == 24) { type = GL_RGB; } else { type = GL_RGBA; } imagesize = ((bpp/8) * width * height); //determine size in bytes of the image cout << imagesize << endl; imagedata = new GLubyte[imagesize]; //allocate memory for our imagedata variable texturestream.read((char*)imagedata,imagesize); //read according the the size of the image and save into imagedata for(GLuint cswap = 0; cswap < (GLuint)imagesize; cswap += (bpp/8)) //loop through and reverse the tga's BGR format to RGB { imagedata[cswap] ^= imagedata[cswap+2] ^= //1st Byte XOR 3rd Byte XOR 1st Byte XOR 3rd Byte imagedata[cswap] ^= imagedata[cswap+2]; } texturestream.close(); //close ifstream because we're done with it cout << "image loaded" << endl; glGenTextures(1, &texID); // Generate OpenGL texture IDs glBindTexture(GL_TEXTURE_2D, texID); // Bind Our Texture glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); // Linear Filtered glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, type, width, height, 0, type, GL_UNSIGNED_BYTE, imagedata); delete imagedata; return true; } //Public loading function for TGA images. Opens TGA file and determines //its type, if any, then loads it and calls the appropriate function. //Returns: TRUE on success, FALSE on failure bool TGA::loadTGA(char *filename) { cout << width << endl; ifstream texturestream; texturestream.open(filename,ios::binary); texturestream.read((char*)header,sizeof(header)); //read 6 bytes into the file, its the header. //if it matches the uncompressed header's first 6 bytes, load it as uncompressed LoadUncompressedTGA(filename,texturestream); return true; } GLubyte* TGA::getImageData() { return imagedata; } GLuint& TGA::getTexID() { return texID; } And here's the quad: void Square::show() { glEnable(GL_TEXTURE_2D); glBindTexture(GL_TEXTURE_2D, texture.texID); //Move to offset glTranslatef( x, y, 0 ); //Start quad glBegin( GL_QUADS ); //Set color to white glColor4f( 1.0, 1.0, 1.0, 1.0 ); //Draw square glTexCoord2f(0.0f, 0.0f); glVertex3f( 0, 0, 0 ); glTexCoord2f(1.0f, 0.0f); glVertex3f( SQUARE_WIDTH, 0, 0 ); glTexCoord2f(1.0f, 1.0f); glVertex3f( SQUARE_WIDTH, SQUARE_HEIGHT, 0 ); glTexCoord2f(0.0f, 1.0f); glVertex3f( 0, SQUARE_HEIGHT, 0 ); //End quad glEnd(); //Reset glLoadIdentity(); }

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This code appears to achieve the return of a null reference in C++

- by Chuck

Hi folks, My C++ knowledge is somewhat piecemeal. I was reworking some code at work. I changed a function to return a reference to a type. Inside, I look up an object based on an identifier passed in, then return a reference to the object if found. Of course I ran into the issue of what to return if I don't find the object, and in looking around the web, many people claim that returning a "null reference" in C++ is impossible. Based on this advice, I tried the trick of returning a success/fail boolean, and making the object reference an out parameter. However, I ran into the roadblock of needing to initialize the references I would pass as actual parameters, and of course there is no way to do this. I retreated to the usual approach of just returning a pointer. I asked a colleague about it. He uses the following trick quite often, which is accepted by both a recent version of the Sun compiler and by gcc: MyType& someFunc(int id) { // successful case here: // ... // fail case: return *static_cast<MyType*>(0); } // Use: ... MyType& mt = somefunc(myIdNum); if (&mt) // test for "null reference" { // whatever } ... I have been maintaining this code base for a while, but I find that I don't have as much time to look up the small details about the language as I would like. I've been digging through my reference book but the answer to this one eludes me. Now, I had a C++ course a few years ago, and therein we emphasized that in C++ everything is types, so I try to keep that in mind when thinking things through. Deconstructing the expression: "*static_cast(0);", it indeed seems to me that we take a literal zero, cast it to a pointer to MyType (which makes it a null pointer), and then apply the dereferencing operator in the context of assigning to a reference type (the return type), which should give me a reference to the same object pointed to by the pointer. This sure looks like returning a null reference to me. Any advice in explaining why this works (or why it shouldn't) would be greatly appreciated. Thanks, Chuck

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Suggest an alternative way to organize/build a database solution.

- by Hamish Grubijan

We are using Visual Studio 2010, but this was first conceived with VS2003. I will forward the best suggestions to my team. The current setup almost makes me vomit. It is a C# solution with most projects containing .sql files. Because we support Microsoft, Oracle, and Sybase, and so home-brewed a pre-processor, much like C preprocessor, except that substitutions are performed by a home-brewed C# program without using yacc and tools like that. #ifdefs are used for conditional macro definitions, and yeah - macros are the way this is done. A macro can expand to another macro or two, but this should eventually terminate. Only macros have #ifdef in them - the rest of the SQL-like code just uses these macros. Now, the various configurations: Debug, MNDebug, MNRelease, Release, SQL_APPLY_ALL, SQL_APPLY_MSFT, SQL_APPLY_ORACLE, SQL_APPLY_SYBASE, SQL_BUILD_OUTPUT_ALL, SQL_COMPILE, as well as 2 more. Also: Any CPU, Mixed Platforms, Win32. What drives me nuts is having to configure it correctly as well as choosing the right one out of 12 x 3 = 36 configurations as well as having to substitute database name depending on the type of database: config, main, or gateway. I am thinking that configuration should be reduced to just Debug, Release, and SQL_APPLY. Also, using 0, 1, and 2 seems so 80s ... Finally, I think my intention to build or not to build 3 types of databases for 3 types of vendors should be configured with just a tic tac toe board like: XOX OOX XXX In this case it would mean build MSFT+CONFIG, all SYBASE, and all GATEWAY. Still, the overall thing which uses a text file and a pre-processor and many configurations seems incredibly clunky. It is year 2010 now and someone out there is bound to have a very clean and/or creative tool/solution. The only pro would be that the existing collection of macros has been well tested. Have you ever had to write SQL that would work for several vendors? How did you do it? SqlVars.txt (Every one of 30 users makes a copy of a template and modifies this to suit their needs): // This is the default parameters file and should not be changed. // You can overwrite any of these parameters by copying the appropriate // section to override into SqlVars.txt and providing your own information. //Build types are 0-Config, 1-Main, 2-Gateway BUILD_TYPE=1 REMOVE_COMMENTS=1 // Login information used when applying to a Microsoft SQL server database SQL_APPLY_MSFT_version=SQL2005 SQL_APPLY_MSFT_database=msftdb SQL_APPLY_MSFT_server=ABC SQL_APPLY_MSFT_user=msftusr SQL_APPLY_MSFT_password=msftpwd // Login information used when applying to an Oracle database SQL_APPLY_ORACLE_version=ORACLE10g SQL_APPLY_ORACLE_server=oradb SQL_APPLY_ORACLE_user=orausr SQL_APPLY_ORACLE_password=orapwd // Login information used when applying to a Sybase database SQL_APPLY_SYBASE_version=SYBASE125 SQL_APPLY_SYBASE_database=sybdb SQL_APPLY_SYBASE_server=sybdb SQL_APPLY_SYBASE_user=sybusr SQL_APPLY_SYBASE_password=sybpwd ... (THIS GOES ON)

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Achieving C# "readonly" behavior in C++

- by Tommy Fisk

Hi guys, this is my first question on stack overflow, so be gentle. Let me first explain the exact behavior I would like to see. If you are familiar with C# then you know that declaring a variable as "readonly" allows a programmer to assign some value to that variable exactly once. Further attempts to modify the variable will result in an error. What I am after: I want to make sure that any and all single-ton classes I define can be predictably instantiated exactly once in my program (more details at the bottom). My approach to realizing my goal is to use extern to declare a global reference to the single-ton (which I will later instantiate at a time I choose. What I have sort of looks like this, namespace Global { extern Singleton& mainInstance; // not defined yet, but it will be later! } int main() { // now that the program has started, go ahead and create the singleton object Singleton& Global::mainInstance = Singleton::GetInstance(); // invalid use of qualified name Global::mainInstance = Singleton::GetInstance(); // doesn't work either :( } class Singleton { /* Some details ommited */ public: Singleton& GetInstance() { static Singleton instance; // exists once for the whole program return instance; } } However this does not really work, and I don't know where to go from here. Some details about what I'm up against: I'm concerned about threading as I am working on code that will deal with game logic while communicating with several third-party processes and other processes I will create. Eventually I would have to implement some kind of synchronization so multiple threads could access the information in the Singleton class without worry. Because I don't know what kinds of optimizations I might like to do, or exactly what threading entails (never done a real project using it), I was thinking that being able to predictably control when Singletons were instantiated would be a Good Thing. Imagine if Process A creates Process B, where B contains several Singletons distributed against multiple files and/or libraries. It could be a real nightmare if I can not reliably ensure the order these singleton objects are instantiated (because they could depend on each other, and calling methods on a NULL object is generally a Bad Thing). If I were in C# I would just use the readonly keyword, but is there any way I can implement this (compiler supported) behavior in C++? Is this even a good idea? Thanks for any feedback.

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When may I ask a question to fellow developers? (Rules before asking questions).

- by Zwei Steinen

I assigned a quite simple task to one junior developer today, and he kept pinging me EVERY 5 minutes for HOURS, asking STEP BY STEP, what to do. Whenever something went wrong, he simply copy&pasted the log and basically wrote, "An exception occurred. What should I do?" So I finally had to tell him, "If you want to be a developer, please start thinking a little bit. Read the error message. That's what they are for!". I also however, tell junior developers to ask questions before spending too much time trying to solve it themselves. This might sound contradictory, but I feel there is some kind of an implicit rule that distinguishes questions that should be asked fairly quickly and that should not (and I try to follow those rules when I ask questions..) So my question is, do you have any rules that you follow, or expect others to follow on asking questions? If so, what are they? Let me start with my own. If you have struggled for more than 90 min, you may ask that question (exceptions exists). If you haven't struggled for more than 15 min, you may not ask that question (if you are sure that the answer can not be found within 15 min, this rule does not have to apply). If it is completely out of your domain and you do not plan to learn that domain, you may ask that question after 15 min (e.g. if I am a java programmer and need to back up the DB, I may ask the DBA what procedure to follow after googling for 15 min). If it is a "local" question, whose answer is difficult to derive or for which resources is difficult to get (e.g. asking an colleague "what method xxx does" etc.), you may ask that question after 15 min. If the answer for it is difficult to derive, and you know that the other person knows the answer, you may ask the question after 15 min (e.g. asking a hibernate expert "What do I need to change else to make this work?". If the process to derive the answer is interesting and is a good learning opportunity, you may ask for hints but you may not ask for answers! What are your rules?

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How to optimize foreach loop in PHP

- by vanneto

First off, I know the title is generic and not fitting. I just couldn't think of a title that could describe my problem. I have a table Recipients in MySQL structured like this: id | email | status 1 foo@bar S 2 bar@baz S 3 abc@def R 4 sta@cko B I need to convert the data into the following XML, depending on the status field. For example: <Recipients> <RecipientsSent>  <recipient>foo@bar</recipient> <recipient>bar@baz</recipient> </RecipientsSent> <RecipientsRegexError> <recipient>abc@def</recipient> </RecipientsRegexError> <RecipientsBlocked> <recipient>sta@cko</recipient> </RecipientsBlocked> </Recipients> I have this PHP code to implement this ($recipients contains an associative array of the db table): <Recipients> <RecipientsSent> <?php foreach ($recipients as $recipient): if ($recipient['status'] == 'S'): echo "<recipient>" . $recipient['email'] . "</recipient>"; endif; endforeach; ?> </RecipientsSent> <RecipientsRegexError> <?php foreach ($recipients as $recipient): if ($recipient['status'] == 'R'): echo "<recipient>" . $recipient['email'] . "</recipient>"; endif; endforeach; ?> </RecipientsRegexError> <?php /** same loop for the B status */ ?> </Recipients> So, this means that if I have 1000 entries in the table and 4 different status' that can be checked, it means that there will be 4 loops, each one executing 1000 times. How can this be done in a more efficient manner? I thought about fetching four different sets from the database, meaning 4 different queries, would that be more efficient? I'm thinking it could be done with one loop but but I can't come up with a solution. Any way this could be done with only one loop?

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Calendar Day View in PHP

- by JamesArmes

I'm working on adding a day view option to an existing calendar solution. Like many people implementing their own calendars, I am trying to model Google Calendars. They have an excellent calendar solution and their day view provides a lot of flexibility. For most part, the implementation is going well; however, I'm having issues when it comes to conflicting events. Essentially, I want the events to share the same space, side by side. Events that start at the same time should have the longest event first. In the example data set I'm working with, I have four events: A: 10:30 - 11:30 B: 13:30 - 14:30 C: 10:30 - 11:00 D: 10:45 - 14:00 I can handle A, C, and D just fine, the problem comes with D. A should be left of C which should be left of D; each taking one third of the width (it's fixed width so I can do simple math to figure that out). The problem is that B should be under A and C, to the left of D. Ideally, B would take up the same amount of space as A and C (two thirds width), but I would even settle for it only taking up only one third width. My array of events looks similar to the following: $events = array( '1030' => array( 'uniqueID1' => array( 'start_time' => '1030', 'end_time' => '1130', ), 'uniqueID2' => array( 'start_time' => '1030', 'end_time' => '1100', ), ), '1045' => array( 'uniqueID3' => array( 'start_time' => '1045', 'end_time' => '1400', ), ), '1330' => array( 'uniqueID3' => array( 'start_time' => '1330', 'end_time' => '1430', ), ), ); My plan is to add some indexes to each event that include how many events it conflicts with (so I can calculate the width) and which position in that series it should be (so I can calculate the left value). However, that doesn't help the B. I'm thinking I might need an algorithm that uses some basic geometry and matrices, but I'm not sure where to begin. Any help is greatly appreciated.

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Translating a C# WCF app into Visual Basic

- by MikeG

I'm trying to write a simple/small Windows Communication Foundation service application in Visual Basic (but I am very novice in VB) and all the good examples I've found on the net are written in C#. So far I've gotten my WCF service application working but now I'm trying to add callback functionality and the program has gotten more complicated. In the C# example code I understand how everything works but I am having trouble translating into VB the portion of code that uses a delegate. Can someone please show the VB equivalent? Here is the C# code sample I'm using for reference: namespace WCFCallbacks { using System; using System.ServiceModel; [ServiceContract(CallbackContract = typeof(IMessageCallback))] public interface IMessage { [OperationContract] void AddMessage(string message); [OperationContract] bool Subscribe(); [OperationContract] bool Unsubscribe(); } interface IMessageCallback { [OperationContract(IsOneWay = true)] void OnMessageAdded(string message, DateTime timestamp); } } namespace WCFCallbacks { using System; using System.Collections.Generic; using System.ServiceModel; public class MessageService : IMessage { private static readonly List<IMessageCallback> subscribers = new List<IMessageCallback>(); //The code in this AddMessage method is what I'd like to see re-written in VB... public void AddMessage(string message) { subscribers.ForEach(delegate(IMessageCallback callback) { if (((ICommunicationObject)callback).State == CommunicationState.Opened) { callback.OnMessageAdded(message, DateTime.Now); } else { subscribers.Remove(callback); } }); } public bool Subscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); if (!subscribers.Contains(callback)) subscribers.Add(callback); return true; } catch { return false; } } public bool Unsubscribe() { try { IMessageCallback callback = OperationContext.Current.GetCallbackChannel<IMessageCallback>(); if (!subscribers.Contains(callback)) subscribers.Remove(callback); return true; } catch { return false; } } } } I was thinking I could do something like this but I don't know how to pass the message string from AddMessage to DoSomething... Dim subscribers As New List(Of IMessageCallback) Public Sub AddMessage(ByVal message As String) Implements IMessage.AddMessage Dim action As Action(Of IMessageCallback) action = AddressOf DoSomething subscribers.ForEach(action) 'Or this instead of the above three lines: 'subscribers.ForEach(AddressOf DoSomething) End Sub Public Sub DoSomething(ByVal callback As IMessageCallback) 'I am also confused by: '((ICommunicationObject)callback).State 'Is that casting the callback object as type ICommunicationObject? 'How is that done in VB? End Sub

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Should I HttpCombine Google Jquery Hosted File?

- by chobo2

Hi I am using something called HttpCombiner: http://code.msdn.microsoft.com/HttpCombiner An HTTP handler that combines multiple CSS, Javascript or URL into one response for faster page load. It can combine, compress and cache response which results in faster page load and better scalability of web application It's a good practice to use many small Javascript and CSS files instead of one large Javascript/CSS file for better code maintainability, but bad in terms of website performance. Although you should write your Javascript code in small files and break large CSS files into small chunks but when browser requests those javascript and css files, it makes one Http request per file. Every Http Request results in a network roundtrip form your browser to the server and the delay in reaching the server and coming back to the browser is called latency. So, if you have four javascripts and three css files loaded by a page, you are wasting time in seven network roundtrips. Within USA, latency is average 70ms. So, you waste 7x70 = 490ms, about half a second of delay. Outside USA, average latency is around 200ms. So, that means 1400ms of waiting. Browser cannot show the page properly until Css and Javascripts are fully loaded. So, the more latency you have, the slower page loads. You can reduce the wait time by using a CDN. Read my previous blog post about using CDN. However, a better solution is to deliver multiple files over one request using an HttpHandler that combines several files and delivers as one output. So, instead of putting many or tag, you just put one and one tag, and point them to the HttpHandler. You tell the handler which files to combine and it delivers those files in one response. This saves browser from making many requests and eliminates the latency. This Http Handler reads the file names defined in a configuration and combines all those files and delivers as one response. It delivers the response as gzip compressed to save bandwidth. Moreover, it generates proper cache header to cache the response in browser cache, so that, browser does not request it again on future visit. Now I am wondering since it can handle adding links should I put in it the jquery file? The reason I am not sure is if it gets combined with my other files I think I might close the advantages of it being hosted on googles servers such as caching(my thinking is if it gets combined it will look different so even if a user has it in it's cache I am not sure if it will use the one for the cahce or not). So should I combine it or only the finals that I am using locally?

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Suggestions In Porting ASP.NET to MVC.NET - Is storing SiteConfiguration in Cache RESTful?

- by DaveDev

I've been tasked with porting/refactoring a Web Application Platform that we have from ASP.NET to MVC.NET. Ideally I could use all the existing platform's configurations to determine the properties of the site that is presented. Is it RESTful to keep a SiteConfiguration object which contains all of our various page configuration data in the System.Web.Caching.Cache? There are a lot of settings that need to be loaded when the user acceses our site so it's inefficient for each user to have to load the same settings every time they access. Some data the SiteConfiguration object contains is as follows and it determines what Master Page / site configuration / style / UserControls are available to the client, public string SiteTheme { get; set; } public string Region { private get; set; } public string DateFormat { get; set; } public string NumberFormat { get; set; } public int WrapperType { private get; set; } public string LabelFileName { get; set; } public LabelFile LabelFile { get; set; } // the following two are the heavy ones // PageConfiguration contains lots of configuration data for each panel on the page public IList<PageConfiguration> Pages { get; set; } // This contains all the configurations for the factsheets we produce public List<ConfiguredFactsheet> ConfiguredFactsheets { get; set; } I was thinking of having a URL structure like this: www.MySite1.com/PageTemplate/UserControl/ the domain determines the SiteConfiguration object that is created, where MySite1.com is SiteId = 1, MySite2.com is SiteId = 2. (and in turn, style, configurations for various pages, etc.) PageTemplate is the View that will be rendered and simply defines a layout for where I'm going to inject the UserControls Can somebody please tell me if I'm completely missing the RESTful point here? I'd like to refactor the platform into MVC because it's better to work in but I want to do it right but with a minimum of reinventing-the-wheel because otherwise it won't get approval. Any suggestions otherwise? Thanks

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Can you call FB.login inside a callback from other FB methods (like FB.getLoginStatus) without triggering popup blockers?

- by Erik Kallevig

I'm trying to set up a pretty basic authentication logic flow with the FB JavaScript SDK to check a user's logged-in status and permissions before performing an action (and prompting the user to login with permissions if they are not)... User types a message into a textarea on my site to post to their Facebook feed and click's a 'post to facebook' button on my site. In response to the click, I check user's logged in status with FB.getLoginStatus In the callback to FB.getLoginStatus, if user is not logged in, prompt them to login (FB.login). In the callback to FB.login I then need to make sure they have the right permissions so I make a call to FB.api('/me/permissions') -- if they don't , I again prompt them to login (FB.login) The problem I'm running into is that anytime I try to call FB.login inside a callback to other FB methods, the browser seems to lose track of the origin of execution (the click) and thus will block the popup. I'm wondering if I'm missing some way to prompt the user to login after checking their status without the browser mistakenly thinking that it's not a user-initiated popup? I've currently fallen back to just calling FB.login() first regardless. The undesired side effect of this approach, however, is that if the user is already logged-in with permissions and I'm still calling FB.login, the auth popup will open and close immediately before continuing, which looks rather buggy despite being functional. It seems like checking a user's login status and permissions before doing something would be a common flow so I feel like I'm missing something. Here's some example code. <div onclick="onClickPostBtn()">Post to Facebook</div> <script> // Callback to click on Post button. function onClickPostBtn() { // Check if logged in, prompt to do so if not. FB.getLoginStatus(function(response) { if (response.status === 'connected') { checkPermissions(response.authResponse.accessToken); } else { FB.login(function(){}, {scope: 'publish_stream'}) } }); } // Logged in, check permissions. function checkPermissions(accessToken) { FB.api('/me/permissions', {'access_token': accessToken}, function(response){ // Logged in and authorized for this site. if (response.data && response.data.length) { // Parse response object to check for permission here... if (hasPermission) { // Logged in with permission, perform some action. } else { // Logged in without proper permission, request login with permissions. FB.login(function(){}, {scope: 'publish_stream'}) } // Logged in to FB but not authorized for this site. } else { FB.login(function(){}, {scope: 'publish_stream'}) } } ); } </script>

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PHP Shared Sessions across Domain

- by bigstylee

Hi, I have seen a few answers to this on SOO but most of these are concerned with the use of subdomains, of which none have worked for me. The common one being that the use of session.cookie_domain, which from my understanding will only work with subdomains. I am interested in a solution that deals with deals with entirely different domains (and includes the possibility of subdomains). Unfortunately project deadlines being what they are, time is not on my side, so I turn to SOO's expertise and experience. The current project brief is to be able to log into one site which currently only stores the user_id in the session and then be able to retrieve this value while on a different domain within the same server enviroment. Session data is being stored/retrieved from a database where the session id is the primary key. I am hoping to find a "light wieght" and "easy" to implement solution. The system is utlising an in-house Model View Controller design pattern, so all requests (including different domains) are run through a single bootstrap script. Using the domain name as a variable, this determines what context to display to the user. One option that did look like to have potential is the use of a hidden image and using the alt tag to set the user id. My first impressions suggest this immediately seems "too easy" (if possible) and riddled with security flaws. Disscuss? Another option which I considered is using the IP and User Agent for authentication but again I feel this not going to be a reliable option due to shared networks and changing IP addresses. My third option (and preferred) which I considered and as yet not seen discussed is using htaccess to fool the user into thinking that they are on a different domain when infact apache is redirecting; something like www.foo.com/index.php?domain=bar.com&controller=news/categoires/1 but displays to the user as www.bar.com/news/categories/1 foo.com represents the "main site domain" which all requests are run through and bar.com is what the user thinks they are accessing. The controller request dictates the page and view being requested. Is this possible? Are there other options? Pros/Cons? Thanks in advanced!!!

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C++ vector pointer/reference problem

- by sub

Please take a look at this example: #include <iostream> #include <vector> #include <string> using namespace std; class mySubContainer { public: string val; }; class myMainContainer { public: mySubContainer sub; }; void doSomethingWith( myMainContainer &container ) { container.sub.val = "I was modified"; } int main( ) { vector<myMainContainer> vec; /** * Add test data */ myMainContainer tempInst; tempInst.sub.val = "foo"; vec.push_back( tempInst ); tempInst.sub.val = "bar"; vec.push_back( tempInst ); // 1000 lines of random code here int i; int size = vec.size( ); myMainContainer current; for( i = 0; i < size; i ++ ) { cout << i << ": Value before='" << vec.at( i ).sub.val << "'" << endl; current = vec.at( i ); doSomethingWith( current ); cout << i << ": Value after='" << vec.at( i ).sub.val << "'" << endl; } system("pause");//i suck } A hell lot of code for an example, I know. Now so you don't have to spend years thinking about what this [should] do[es]: I have a class myMainContainer which has as its only member an instance of mySubContainer. mySubContainer only has a string val as member. So I create a vector and fill it with some sample data. Now, what I want to do is: Iterate through the vector and make a separate function able to modify the current myMainContainer in the vector. However, the vector remains unchanged as the output tells: 0: Value before='foo' 0: Value after='foo' 1: Value before='bar' 1: Value after='bar' What am I doing wrong? doSomethingWith has to return void, I can't let it return the modified myMainContainer and then just overwrite it in the vector, that's why I tried to pass it by reference as seen in the doSomethingWith definition above.

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Object relationships

- by Hammerstein

This stems from a recent couple of posts I've made on events and memory management in general. I'm making a new question as I don't think the software I'm using has anything to do with the overall problem and I'm trying to understand a little more about how to properly manage things. This is ASP.NET. I've been trying to understand the needs for Dispose/Finalize over the past few days and believe that I've got to a stage where I'm pretty happy with when I should/shouldn't implement the Dispose/Finalize. 'If I have members that implement IDisposable, put explicit calls to their dispose in my dispose method' seems to be my understanding. So, now I'm thinking maybe my understanding of object lifetimes and what holds on to what is just wrong! Rather than come up with some sample code that I think will illustrate my point, I'm going to describe as best I can actual code and see if someone can talk me through it. So, I have a repository class, in it I have a DataContext that I create when the repository is created. I implement IDisposable, and when my calling object is done, I call Dispose on my repository and explicitly call DataContext.Dispose( ). Now, one of the methods of this class creates and returns a list of objects that's handed back to my front end. Front End - Controller - Repository - Controller - Front End. (Using Redgate Memory Profiler, I take a snapshot of my software when the page is first loaded). My front end creates a controller object on page load and then makes a request to the repository sending back a list of items. When the page is finished loading, I call Dispose on the controller which in turn calls dispose on the context. In my mind, that should mean that my connection is closed and that I have no instances of my controller class. If I then refresh the page, it jumps to two 'Live' instances of the controller class. If I look at the object retention graph, the objects I created in my call to the list are being held onto ultimately by what looks like Linq. The controller/repository aside, if I create a list of objects somewhere, or I create an object and return it somewhere, am I safe to just assume that .NET will eventually come and clean things up for me or is there a best practice? The 'Live' instances suggest to me that these are still in memory and active objects, the fact that RMP apparently forces GC doesn't mean anything?

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JQuery performance issue (Or just bad CODING!)

- by ferronrsmith

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Is 4-5 years the “Midlife Crisis” for a programming career?

- by Jeffrey

I’ve been programming C# professionally for a bit over 4 years now. For the past 4 years I’ve worked for a few small/medium companies ranging from “web/ads agencies”, small industry specific software shops to a small startup. I've been mainly doing "business apps" that involves using high-level programming languages (garbage collected) and my overall experience was that all of the works I’ve done could have been more professional. A lot of the things were done incorrectly (in a rush) mainly due to cost factor that people always wanted something “now” and with the smallest amount of spendable money. I kept on thinking maybe if I could work for a bigger companies or a company that’s better suited for programmers, or somewhere that's got the money and time to really build something longer term and more maintainable I may have enjoyed more in my career. I’ve never had a “mentor” that guided me through my 4 years career. I am pretty much blog / google / self taught programmer other than my bachelor IT degree. I’ve also observed another issue that most so called “senior” programmer in “my working environment” are really not that senior skill wise. They are “senior” only because they’ve been a long time programmer, but the code they write or the decisions they make are absolutely rubbish! They don't want to learn, they don't want to be better they just want to get paid and do what they've told to do which make sense and most of us are like that. Maybe that’s why they are where they are now. But I don’t want to become like them I want to be better. I’ve run into a mental state that I no longer intend to be a programmer for my future career. I started to think maybe there are better things out there to work on. The more blogs I read, the more “best practices” I’ve tried the more I feel I am drifting away from “my reality”. But I am not a great programmer otherwise I don't think I am where I am now. I think 4-5 years is a stage that can be a step forward career wise or a step out of where you are. I just wanted to hear what other have to say about what I’ve mentioned above and whether you’ve experienced similar situation in your past programming career and how you dealt with it. Thanks.

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Can't get jQuery to get focus on cloned input fields

- by Rebel1Moon

I have a page that needs to create dynamic form fields as often as the user needs, and I am trying to use Ajax to tie it in to my database for faster form entry and to prevent user typos. So, I have put my Ajax returned data into popup div, the user selects, then the form field is filled in. The problem comes on the cloned fields. They don't seem to want to bring up the popup div when focused. I am thinking it is something to do with when they get created/added to the DOM. Here is my JS that creates the clones: $(document).ready(function() { var regex = /^(.*)(\d)+$/i; var cloneIndex = $(".clonedInput").length; $("button.clone").live("click", function(){ $(this).parents(".clonedInput").clone() .appendTo("#course_container") .attr("id", "clonedInput" + cloneIndex) .find("*").each(function() { var id = this.id || ""; var match = id.match(regex) || []; if (match.length == 3) { this.id = match[1] + (cloneIndex); } }); cloneIndex++; numClones=cloneIndex-1; //alert("numClones "+numClones); }); Here is where I expect to be able to get focus on the correct cloned field and call the popup. The baker_equiv0 id is original code, whereas baker_equiv1 is the first clone. $('#baker_equiv0').focus(function() { \\ THIS CODE WORKS $('.popup').fadeIn(500); $('#results').empty(); // document.enter_data.baker_equiv1.value="test"; THIS LINE WORKS //alert("numClones "+numClones); }); $('#baker_equiv1').focus(function() { // THIS DOESN'T EVER FIRE alert("numClones "+numClones); $('.popup').fadeIn(500); $('#results').empty(); }); Here is the HTML with the form: <label for="baker_equiv" class="">Baker Equivalent: <span class="requiredField">*</span></label> <input type="text" class="cinputsa" name="baker_equiv[]" id="baker_equiv0" size="8" ONKEYUP="get_equiv(this.value);"> If I put this in the HTML code above, it works fine: onfocus="alert(this.id)" I'd also be interested in how to adjust the JS code to work based on the id array created rather than having to copy code for each potential set of fields clones, i.e., baker_equiv[] rather than baker_equiv0, baker_equiv1, etc. Thanks all!

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A versioning workflow for multiple similar (but not identical) deployments

- by rs77

I'm currently employed at a small non-tech organisation and have been given the role of coding the organisations' website. While I have enjoyed the task and have learnt much with web dev I've encountered a few issues that I'm hoping someone will be able to help with me or at least point me in the right direction on. A little background: The site I work on has subdomains that each have their own separate WordPress installation on - as this has been the easiest "backend" admin panel for the type of user who will be responsible for updating content (etc). Within the organisation I work under the Marketing Manager (MM) and I code according to his style guide and wire frames. While we have been working with only one subdomain since the beginning of the year the project has been relatively simple and straightforward. However, lately the workflow is becoming a little more complicated as our original subdomain has been copied over to the other subdomains. Each of the new subdomains receives minor edits to their stylesheets (eg. different pictures for background, slightly different colours here and there, etc). The issue: At the moment managing all the different subdomains has been "bearable", but the straw that's braking the camel's back at the moment has been the slight reversions the MM has required now that the CEO has seen the final product. The problem I'm having with reversions in stylesheets is that the CEO will one week state that he likes change "X" and then as the MM and I continue to modify the site (to now "Z"), will another week state that he wants us to change "X" to "W" but keeping most of the changes made in "Y". What I'm looking for is something that allows for: tracking file changes reverting changes made (or reverting back to 'a' from 'e' but including changes 'b' & 'c') easily upload necessary files to their respective WP-theme installation Does anything out there come close to addressing these issues? If so, what? Thanks for any help! PS - I'm learning Git at the moment and it seems to do the "tracking file changes" quite nicely. Haven't learnt about the reverting changes bit yet, though. Maybe for my final point I'm thinking of creating a shell script to automatically upload the files to their folders. Does Git do this too though? Addendum (alexbbrown) I had a similar problem: I ran a custom version of mediawiki where I installed various extensions in the versioned core (with svn). Each of the extensions required an section in the confit file, but the confit file also needed local configuration for each of several deployments. I could have implemented it using includes, but they would not be versioned; and rebasing branches each time is a chore. +50 experience points for a good answer in git.

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