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• Time complexity with bit cost

  - by Keyser

  I think I might have completely misunderstood bit cost analysis. I'm trying to wrap my head around the concept of studying an algorithm's time complexity with respect to bit cost (instead of unit cost) and it seems to be impossible to find anything on the subject. Is this considered to be so trivial that no one ever needs to have it explained to them? Well I do. (Also, there doesn't even seem to be anything on wikipedia which is very unusual). Here's what I have so far: The bit cost of multiplication and division of two numbers with n bits is O(n^2) (in general?) So, for example: int number = 2; for(int i = 0; i < n; i++ ){ number = i*i; } has a time complexity with respect to bit cost of O(n^3), because it does n multiplications (right?) But in a regular scenario we want the time complexity with respect to the input. So, how does that scenario work? The number of bits in i could be considered a constant. Which would make the time complexity the same as with unit cost except with a bigger constant (and both would be linear). Also, I'm guessing addition and subtraction can be done in constant time, O(1). Couldn't find any info on it but it seems reasonable since it's one assembler operation.

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• Understanding CSRF - Simple Question

  - by byronh

  I know this might make me seem like an idiot, I've read everything there is to read about CSRF and I still don't understand how using a 'challenge token' would add any sort of prevention. Please help me clarify the basic concept, none of the articles and posts here on SO I read seemed to really explicitly state what value you're comparing with what. From OWASP: In general, developers need only generate this token once for the current session. After initial generation of this token, the value is stored in the session and is utilized for each subsequent request until the session expires. If I understand the process correctly, this is what happens. I log in at http://example.com and a session/cookie is created containing this random token. Then, every form includes a hidden input also containing this random value from the session which is compared with the session/cookie upon form submission. But what does that accomplish? Aren't you just taking session data, putting it in the page, and then comparing it with the exact same session data? Seems like circular reasoning. These articles keep talking about following the "same-origin policy" but that makes no sense, because all CSRF attacks ARE of the same origin as the user, just tricking the user into doing actions he/she didn't intend. Is there any alternative other than appending the token to every single URL as a query string? Seems very ugly and impractical, and makes bookmarking harder for the user.

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• Architectural conundrum

  - by Dejan

  The worst thing when working on a one man project is the lack of input that you usually get from your coworkers. And because of the lack of that you tend to make obvious mistakes. After going down that road for some time I would need some help from the community. I started a little home-brew project that should turn into a portal of some sorts. And the main thing that is bothering me is the persistence layer that i have concocted. It should be completely separated from the presentation layer for starters and a OR mapper is also somewhere. This is because I have multiple data stores that have to be used. So the base idea was that the individual "repositories" operate each on their individual database and that the business layer then aggregates the business objects which are then transformed in the presentation layer into view objects. The main problem I face is the following: Multiple classes for the same concept - There is a DAL representation of a user and BL representation of user and a view representation of a user. I can handle the transformation with a tool but is this really the right way. I mean they are all nicely separated, but the overhead is quite something. What do you think? Am I going too deep into the separation of concern rabbit hole or is this still normal?

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• Disabling normal link behaviour on click with an if statement in Jquery?

  - by Qwibble

  I've been banging my head with this all day, trying anything and everything I can think of to no gain. I'm no Jquery guru, so am hoping someone here can help me out. What I'm trying to do in pseudo code (concept) seems practical and easy to implement, but obviously not so =D What I have is a navigation sidebar, with sub menu's within some li's, and a link at the head of each li. When a top level link is clicked, I want the jquery to check if the link has a sibling ul. If it does, the link doesn't act like a link, but slides down the sibling sub nav. If there isn't one, the link should act normally. Here's where I'm at currently, what am I doing wrong? $('ul.navigation li a').not('ul.navigation li ul li a').click(function (){ if($(this).parent().contains('ul')){ $('ul.navigation li ul').slideUp(); $(this).siblings('ul').slideDown(); return false; } else{ alert('Link Clicked') // Maybe do some more stuff in here... } }); Any ideas?

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• Turing Machine & Modern Computer

  - by smwikipedia

  I heard a lot that modern computers are based on Turing machine. I'd like to share my understanding and hear your comments. I think the computer is a big general-purpose Turing machine. Each program we write is a small specific-purpose Turing machine. The classical Turing machine do its job based on the input and its current state inside and so do our programs. Let's take a running program (a process) as an example. We know that in the process's address space, there's areas for stack, heap, and code. A classical Turing machine doesn't have the ability to remember many things, so we borrow the concept of stack from the push-down automaton. The heap and stack areas contains the state of our specific-purpose Turing machine (our program). The code area represents the logic of this small Turing machine. And various I/O devices supply input to this Turing machine. The above is my naive understanding about the working paradigm of modern computer. I couln't wait to hear your comments. Thanks very much.

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• Spring MVC: How to resolve the path to subdirectories of the root 'JSP' folder in a web application

  - by chrisjleu

  What is a simple way to resolve the path to a JSP file that is not located in the root JSP directory of a web application using SpringMVCs viewResolvers? For example, suppose we have the following web application structure: web-app |-WEB-INF |-jsp |-secure |-admin.jsp |-admin2.jsp index.jsp login.jsp I would like to use some out-of-the-box components to resolve the JSP files within the jsp root folder and the secure subdirectory. I have a *-servlet.xml file that defines: an out-of-the-box, InternalResourceViewResolver: <bean id="jspViewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver"> <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"></property> <property name="prefix" value="/WEB-INF/jsp/"></property> <property name="suffix" value=".jsp"></property> </bean> a handler mapping: <bean id="handlerMapping" class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping"> <property name="mappings"> <props> <prop key="/index.htm">urlFilenameViewController</prop> <prop key="/login.htm">urlFilenameViewController</prop> <prop key="/secure/**">urlFilenameViewController</prop> </props> </property> </bean> an out-of-the-box UrlFilenameViewController controller: <bean id="urlFilenameViewController" class="org.springframework.web.servlet.mvc.UrlFilenameViewController"> </bean> The problem I have is that requests to the JSPs in the secure directory cannot be resolved, as the jspViewResolver only has a prefix defined as /jsp/ and not /jsp/secure/. Is there a way to handle subdirectories like this? I would prefer to keep this structure because I'm also trying to make use of Spring Security and having all secure pages in a subdirectory is a nice way to do this. There's probably a simple way to acheive this but I'm new to Spring and the Spring MVC framework so any pointers would be appreciated.

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• question regarding templatization of virtual function

  - by jan

  Hi, I am new to this forum and sorry If I am repeating this question. I know that you cannot templatize the virtual function and I do understand the concept behind it. But I still need a way to get across some errors I am getting it. I am able to make my stuff work but it doesn't look to me. Here's the deal, I have class called System, #include "Vector.h" class System { virtual void VectorToLocal(Vector<T>& global_dir,const Vector<T>* global_pos = 0) const = 0; }; class UnresolvedSystem : public System { virtual void VectorToLocal(Vector<T>& global_dir,const Vector<T>* global_pos = 0) const { //do something } }; In Vector.h tenplate<typename T> class Vector { //some functions }; See now I want to templatize VectorToLocal in system.h to take just Vector, but I cannot do it as it is a virtual function. I want a work around. I know I can have VectorToLocal take Vector, Vector etc as arguments. But I do not want to do it. Any help would be really appreciated. Thanks in advance, Jan

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• Is this OleDbDataAdapter bug

  - by ????

  It doesn't look to me OleDbDataAdapter should throw an exception on trying to fill DataSet for a db table column of type decimal(28,3). The message is "The numerical value is too large to fit into a 96 bit decimal". Could you just check this, I have no significant experience with ADO.NET and OLE DB components? The VB.NET code we have in the application is this: Dim dbDataSet As New DataSet Dim dbDataAdapter As OleDbDataAdapter Dim dbCommand As OleDbCommand Dim conn As OleDbConnection Dim connectionString As String 'parts where connectionString is set conn = New OleDbConnection(connectionString) 'part where sqlQuery is set but it ends up being "SELECT Price As 'Price' From PricebookView" - Price is of type decimal(28,3) dbCommand = New OleDbCommand(sqlQuery, conn) dbCommand.CommandTimeout = cmdTimeout dbDataAdapter = New OleDbDataAdapter(dbCommand) dbDataAdapter.Fill(dbDataSet) The last line is where the exception is thrown and the top of the stack trace is: at System.Data.ProviderBase.DbBuffer.ReadNumeric(Int32 offset) at System.Data.OleDb.ColumnBinding.Value_NUMERIC() at System.Data.OleDb.ColumnBinding.Value() at System.Data.OleDb.OleDbDataReader.GetValues(Object[] values) at System.Data.ProviderBase.DataReaderContainer.CommonLanguageSubsetDataReader.GetValues(Object[] values) at System.Data.ProviderBase.SchemaMapping.LoadDataRow() at System.Data.Common.DataAdapter.FillLoadDataRow(SchemaMapping mapping) at System.Data.Common.DataAdapter.FillFromReader(DataSet dataset, DataTable datatable, String srcTable, DataReaderContainer dataReader, Int32 startRecord, Int32 maxRecords, DataColumn parentChapterColumn, Object parentChapterValue) at System.Data.Common.DataAdapter.Fill(DataSet dataSet, String srcTable, IDataReader dataReader, Int32 startRecord, Int32 maxRecords) at System.Data.Common.DbDataAdapter.FillInternal(DataSet dataset, DataTable[] datatables, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet, Int32 startRecord, Int32 maxRecords, String srcTable, IDbCommand command, CommandBehavior behavior) at System.Data.Common.DbDataAdapter.Fill(DataSet dataSet) ... I am not sure why does it try to set the value to Int32. Thank you for the time !

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• AssertionFailure: "null identifier" - FluentNH + SQLServerCE

  - by Stefan

  The code fails at session.Save(employee); with AssertionFailure "null identifier". What am I doing wrong? using FluentNHibernate.Cfg; using FluentNHibernate.Cfg.Db; using FluentNHibernate.Mapping; using NHibernate; using NHibernate.Cfg; using NHibernate.Tool.hbm2ddl; namespace FNHTest { public class Employee { public virtual int Id { get; private set; } public virtual string Name { get; set; } public virtual string Surname { get; set; } } public class EmployeeMap : ClassMap { public EmployeeMap() { Id(e = e.Id); Map(e = e.Name); Map(e = e.Surname); } } public class DB { private static ISessionFactory mySessionFactory = null; private static ISessionFactory SessionFactory { get { if (mySessionFactory == null) { mySessionFactory = Fluently.Configure() .Database(MsSqlCeConfiguration.Standard .ConnectionString("Data Source=MyDB.sdf")) .Mappings(m = m.FluentMappings.AddFromAssemblyOf()) .ExposeConfiguration(BuildSchema) .BuildSessionFactory(); } return mySessionFactory; } } private static void BuildSchema(Configuration configuration) { SchemaExport schemaExport = new SchemaExport(configuration); schemaExport.Execute(false, true, false); } public static ISession OpenSession() { return SessionFactory.OpenSession(); } } public class Program { public static void Main(string[] args) { var employee = new Employee { Name = "John", Surname = "Smith" }; using (ISession session = DB.OpenSession()) { session.Save(employee); } } } }

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• Creating foreach loops using Code Igniter controller and view

  - by Tim

  Hello, This is a situation I have found myself in a few times and I just want clear it up once and for all. Best just to show you what I need to do in some example code. My Controller function my_controller() { $id = $this->uri->segment(3); $this->db->from('cue_sheets'); $this->db->where('id', $id); $data['get_cue_sheets'] = $this->db->get(); $this->db->from('clips'); $this->db->where('sheet_id', ' CUE SHEET ID GOES IN HERE ??? '); $data['get_clips'] = $this->db->get(); $this->load->view('show_sheets_and_clips', $data); } My View <?php if($get_cue_sheets->result_array()) { ?> <?php foreach($get_cue_sheets->result_array() as $sheetRow): ?> <h1><?php echo $sheetRow['sheet_name']; ?></h1> <br/> <?php if($get_clips->result_array()) { ?> <ul> <?php foreach($get_clips->result_array() as $clipRow): ?> <li><?php echo $clipRow['clip_name']; ?></li> <?php endforeach; ?> </ul> <?php } else { echo 'No Clips Found'; } ?> <?php endforeach; ?> <?php } ?> The problem I am having is the concept of passing data back to the controller from the view as I am sending the Database Queries off to the view as an array, when I really need to get some more information as to which sheet ID I am looking for to show the relevant clips. I hope this makes sense to someone out there. Thanks, Tim

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• PHP OOP: Providing Domain Entities with "Identity"

  - by sunwukung

  Bit of an abstract problem here. I'm experimenting with the Domain Model pattern, and barring my other tussles with dependencies - I need some advice on generating Identity for use in an Identity Map. In most examples for the Data Mapper pattern I've seen (including the one outlined in this book: http://apress.com/book/view/9781590599099) - the user appears to manually set the identity for a given Domain Object using a setter: $UserMapper = new UserMapper; //returns a fully formed user object from record sets $User = $UserMapper->find(1); //returns an empty object with appropriate properties for completion $UserBlank = $UserMapper->get(); $UserBlank->setId(); $UserBlank->setOtherProperties(); Now, I don't know if I'm reading the examples wrong - but in the first $User object, the $id property is retrieved from the data store (I'm assuming $id represents a row id). In the latter case, however, how can you set the $id for an object if it has not yet acquired one from the data store? The problem is generating a valid "identity" for the object so that it can be maintained via an Identity Map - so generating an arbitrary integer doesn't solve it. My current thinking is to nominate different fields for identity (i.e. email) and demanding their presence in generating blank Domain Objects. Alternatively, demanding all objects be fully formed, and using all properties as their identity...hardly efficient. (Or alternatively, dump the Domain Model concept and return to DBAL/DAO/Transaction Scripts...which is seeming increasingly elegant compared to the ORM implementations I've seen...)

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• How to map coordinates in AxesImage to coordinates in saved image file?

  - by Vebjorn Ljosa

  I use matplotlib to display a matrix of numbers as an image, attach labels along the axes, and save the plot to a PNG file. For the purpose of creating an HTML image map, I need to know the pixel coordinates in the PNG file for a region in the image being displayed by imshow. I have found an example of how to do this with a regular plot, but when I try to do the same with imshow, the mapping is not correct. Here is my code, which saves an image and attempts to print the pixel coordinates of the center of each square on the diagonal: import numpy as np import matplotlib.pyplot as plt fig = plt.figure() ax = fig.add_axes([0.1, 0.1, 0.8, 0.8]) axim = ax.imshow(np.random.random((27,27)), interpolation='nearest') for x, y in axim.get_transform().transform(zip(range(28), range(28))): print int(x), int(fig.get_figheight() * fig.get_dpi() - y) plt.savefig('foo.png', dpi=fig.get_dpi()) Here is the resulting foo.png, shown as a screenshot in order to include the rulers: The output of the script starts and ends as follows: 73 55 92 69 111 83 130 97 149 112 … 509 382 528 396 547 410 566 424 585 439 As you see, the y-coordinates are correct, but the x-coordinates are stretched: they range from 73 to 585 instead of the expected 135 to 506, and they are spaced 19 pixels o.c. instead of the expected 14. What am I doing wrong?

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• Error in creating trigger using PHP script.. Please help!!!! Geeks

  - by Parth

  I've been successful in creating a simple trigger with a PHP script. The problem comes when I have to use "DELIMITER" in my trigger creating because I have nested if/then statements. For example, the following DOES work: $sql = 'CREATE TRIGGER `database`.`detail` BEFORE INSERT on `database`.`vibez_detail` FOR EACH ROW set @a=new.realtime_value'; $junk = mysqli_query($link, $sql); However, if I need to use "DELIMITER" I get errors galore. Here's what works if I go to the MySQL client at the server: DELIMITER $$; DROP TRIGGER `database`.`detail`$$ CREATE TRIGGER `database`.`detail` BEFORE INSERT on `database`.`vibez_detail` FOR EACH ROW BEGIN set new.data_rate = 69; insert into alarm_trips_parent values (null, new.data_rate, 6969, now()); set @tripped_time = now(); set @tripped:=true; end if; end if; END$$ DELIMITER ;$$ How can I construct the PHP code to get this to work? Seems the mysqli_query($link, $sql) chokes as soon as I put "DELIMITER" in the $sql variable. I get the following error when I attempt to do so: Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DELIMITER //; CREATE TRIGGER `database`.`detail` BEFORE INS' at line 1 Even The concept for using mysqli_multi_query(); didn't worked for me.... :(

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• Common practice for higher-order-polymorphism in scala

  - by raichoo

  Hi, I'm trying to grasp higher-order-polymophism in scala by implementing a very basic interface that describes a monad but I come across a problem that I don't really understand. I implemented the same with C++ and the code looks like this: #include <iostream> template <typename T> class Value { private: T value; public: Value(const T& t) { this->value = t; } T get() { return this->value; } }; template < template <typename> class Container > class Monad { public: template <typename A> Container<A> pure(const A& a); }; template <template <typename> class Container> template <typename A> Container<A> Monad<Container>::pure(const A& a) { return Container<A>(a); } int main() { Monad<Value> m; std::cout << m.pure(1).get() << std::endl; return 0; } When trying to do the same with scala I fail: class Value[T](val value: T) class Monad[Container[T]] { def pure[A](a: A): Container[A] = Container[A](a) } object Main { def main(args: Array[String]): Unit = { val m = new Monad[Value] m.pure(1) } } The compiler complains about: [raichoo@lain:Scala]:434> scalac highorder.scala highorder.scala:5: error: not found: value Container Container[A](a) ^ one error found What am I doing wrong here? There seems to be a fundamental concept I don't seem to understand about scala typeconstructors. Regards, raichoo

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• JPA @ManyToMany on only one side?

  - by Ethan Leroy

  I am trying to refresh the @ManyToMany relation but it gets cleared instead... My Project class looks like this: @Entity public class Project { ... @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER) @JoinTable(name = "PROJECT_USER", joinColumns = @JoinColumn(name = "PROJECT_ID", referencedColumnName = "ID"), inverseJoinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID")) private Collection<User> users; ... } But I don't have - and I don't want - the collection of Projects in the User entity. When I look at the generated database tables, they look good. They contain all columns and constraints (primary/foreign keys). But when I persist a Project that has a list of Users (and the users are still in the database), the mapping table doesn't get updated gets updated but when I refresh the project afterwards, the list of Users is cleared. For better understanding: Project project = ...; // new project with users that are available in the db System.out.println(project getUsers().size()); // prints 5 em.persist(project); System.out.println(project getUsers().size()); // prints 5 em.refresh(project); System.out.println(project getUsers().size()); // prints 0 So, how can I refresh the relation between User and Project?

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• database schema eligible for delta synchronization

  - by WilliamLou

  it's a question for discussion only. Right now, I need to re-design a mysql database table. Basically, this table contains all the contract records I synchronized from another database. The contract record can be modified, deleted or users can add new contract records via GUI interface. At this stage, the table structure is exactly the same as the Contract info (column: serial number, expiry date etc.). In that case, I can only synchronize the whole table (delete all old records, replace with new ones). If I want to delta(only synchronize with modified, new, deleted records) synchronize the table, how should I change the database schema? here is the method I come up with, but I need your suggestions because I think it's a common scenario in database applications. 1)introduce a sequence number concept/column: for each sequence, mark the new added records, modified records, deleted records with this sequence number. By recording the last synchronized sequence number, only pass those records with higher sequence number; 2) because deleted contracts can be added back, and the original table has primary key constraints, should I create another table for those deleted records? or add a flag column to indicate if this contract has been deleted? I hope I explain my question clearly. Anyway, if you know any articles or your own suggestions about this, please let me know. Thanks!

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• Dependecy Injection with Massive ORM: dynamic trouble

  - by Sergi Papaseit

  I've started working on an MVC 3 project that needs data from an enormous existing database. My first idea was to go ahead and use EF 4.1 and create a bunch of POCO's to represent the tables I need, but I'm starting to think the mapping will get overly complicated as I only need some of the columns in some of the tables. (thanks to Steven for the clarification in the comments. So I thought I'd give Massive ORM a try. I normally use a Unit of Work implementation so I can keep everything nicely decoupled and can use Dependency Injection. This is part of what I have for Massive: public interface ISession { DynamicModel CreateTable<T>() where T : DynamicModel, new(); dynamic Single<T>(string where, params object[] args) where T : DynamicModel, new(); dynamic Single<T>(object key, string columns = "*") where T : DynamicModel, new(); // Some more methods supported by Massive here } And here's my implementation of the above interface: public class MassiveSession : ISession { public DynamicModel CreateTable<T>() where T : DynamicModel, new() { return new T(); } public dynamic Single<T>(string where, params object[] args) where T: DynamicModel, new() { var table = CreateTable<T>(); return table.Single(where, args); } public dynamic Single<T>(object key, string columns = "*") where T: DynamicModel, new() { var table = CreateTable<T>(); return table.Single(key, columns); } } The problem comes with the First(), Last() and FindBy() methods. Massive is based around a dynamic object called DynamicModel and doesn't define any of the above method; it handles them through a TryInvokeMethod() implementation overriden from DynamicObject instead: public override bool TryInvokeMember(InvokeMemberBinder binder, object[] args, out object result) { } I'm at a loss on how to "interface" those methods in my ISession. How could my ISession provide support for First(), Last() and FindBy()? Put it another way, how can I use all of Massive's capabilities and still be able to decouple my classes from data access?

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• About updating a View using in iPhone using Objective C.

  - by Tattat

  I have a scene, called testScene, it works like this: @interface testScene : myScene { IBOutlet UIView *subview; IBOutlet UIView *drawingCanvasView; IBOutlet UIButton *update; } - (void)updateDrawingCanvas: (id) sender; and when the user click the button, update, it will run the updateDrawingCanvas method. So, I have a drawingCanvasView, which gave a drawingCanvas.h, and .m, it like this: #import <UIKit/UIKit.h> @interface DrawingCanvasView : UIView { CGImageRef image; } -(void)setNeedsDisplayInRect:(CGContextRef)context; @end In the DrawingCanvasView, I have a drawRect method like this: CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 2.0); CGContextSetStrokeColorWithColor(context, [UIColor redColor].CGColor); CGContextMoveToPoint(context, 0.0f, 0.0f); CGContextAddLineToPoint(context, 100.0f, 100.0f); CGContextStrokePath(context); And I want the user click the button, and execute this, so I added a new method called setNeedsDisplayInRect: CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetLineWidth(context, 2.0); CGContextSetStrokeColorWithColor(context, [UIColor yellowColor].CGColor); CGContextMoveToPoint(context, 0.0f, 0.0f); CGContextAddLineToPoint(context, 200.0f, 200.0f); CGContextStrokePath(context); But I can't called that in my updateDrawingCanvas method, it work like this: - (void)updateDrawingCanvas: (id) sender{ NSLog(@"loaded"); [DrawingCanvasView setNeedsDisplayInRect:UIGraphicsGetCurrentContext()]; } It my logic / concept right? or something I did wrong, thx.

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• Help needed in grokking password hashes and salts

  - by javafueled

  I've read a number of SO questions on this topic, but grokking the applied practice of storing a salted hash of a password eludes me. Let's start with some ground rules: a password, "foobar12" (we are not discussing the strength of the password). a language, Java 1.6 for this discussion a database, postgreSQL, MySQL, SQL Server, Oracle Several options are available to storing the password, but I want to think about one (1): Store the password hashed with random salt in the DB, one column Found on SO and elsewhere is the automatic fail of plaintext, MD5/SHA1, and dual-columns. The latter have pros and cons MD5/SHA1 is simple. MessageDigest in Java provides MD5, SHA1 (through SHA512 in modern implementations, certainly 1.6). Additionally, most RDBMSs listed provide methods for MD5 encryption functions on inserts, updates, etc. The problems become evident once one groks "rainbow tables" and MD5 collisions (and I've grokked these concepts). Dual-column solutions rest on the idea that the salt does not need to be secret (grok it). However, a second column introduces a complexity that might not be a luxury if you have a legacy system with one (1) column for the password and the cost of updating the table and the code could be too high. But it is storing the password hashed with a random salt in single DB column that I need to understand better, with practical application. I like this solution for a couple of reasons: a salt is expected and considers legacy boundaries. Here's where I get lost: if the salt is random and hashed with the password, how can the system ever match the password? I have theory on this, and as I type I might be grokking the concept: Given a random salt of 128 bytes and a password of 8 bytes ('foobar12'), it could be programmatically possible to remove the part of the hash that was the salt, by hashing a random 128 byte salt and getting the substring of the original hash that is the hashed password. Then re hashing to match using the hash algorithm...??? So... any takers on helping. :) Am I close?

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• How can I work around SQL Server - Inline Table Value Function execution plan variation based on par

  - by Ovidiu Pacurar

  Here is the situation: I have a table value function with a datetime parameter ,lest's say tdf(p_date) , that filters about two million rows selecting those with column date smaller than p_date and computes some aggregate values on other columns. It works great but if p_date is a custom scalar value function (returning the end of day in my case) the execution plan is altered an the query goes from 1 sec to 1 minute execution time. A proof of concept table - 1K products, 2M rows: CREATE TABLE [dbo].[POC]( [Date] [datetime] NOT NULL, [idProduct] [int] NOT NULL, [Quantity] [int] NOT NULL ) ON [PRIMARY] The inline table value function: CREATE FUNCTION tdf (@p_date datetime) RETURNS TABLE AS RETURN ( SELECT idProduct, SUM(Quantity) AS TotalQuantity, max(Date) as LastDate FROM POC WHERE (Date < @p_date) GROUP BY idProduct ) The scalar value function: CREATE FUNCTION [dbo].[EndOfDay] (@date datetime) RETURNS datetime AS BEGIN DECLARE @res datetime SET @res=dateadd(second, -1, dateadd(day, 1, dateadd(ms, -datepart(ms, @date), dateadd(ss, -datepart(ss, @date), dateadd(mi,- datepart(mi,@date), dateadd(hh, -datepart(hh, @date), @date)))))) RETURN @res END Query 1 - Working great SELECT * FROM [dbo].[tdf] (getdate()) The end of execution plan: Stream Aggregate Cost 13% <--- Clustered Index Scan Cost 86% Query 2 - Not so great SELECT * FROM [dbo].[tdf] (dbo.EndOfDay(getdate())) The end of execution plan: Stream Aggregate Cost 4% <--- Filter Cost 12% <--- Clustered Index Scan Cost 86%

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• Is there the equivalent of cloud computing for modems?

  - by morpheous

  I asked this question on SF, and someone recommended that I ask it here - (I don't think I have enough points to move a question from SF to SO - and in any case, I don't know how to do it - so here is the question again): I am interested in the concept of PAAS (platform as a service). However, all talk about SAAS/PAAS seems to focus on only the computer itself - not its peripherals. Is it possible to 'outsource' modems as a resource - so that an app running remotely can pump data to a modem in the cloud? As a bit of background to the question, a group of us are thinking of starting a company that offers similar services to companies like twilio etc - but I want to 'outsource' both the computing hardware (thats PAAS - the easy bit) and the modems (thats what I cant seem to find any info on). Does anyone know if modems can be bundled as part of a PAAS service? - alternatively, is there a way that an application running on one computer can communicate (i.e. pump data) to a remote modem residing on another machine?. I assume I can come up with some protocol over UDP or TCP - but there is no point reinventing the wheel - if such a protocol like that already exists (or if it some open source software allows one to do this). Any suggestions on how to solve this problem?

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• Flexible CMS for non-programmers

  - by Bunkerbewohner

  Hello! I'm looking for a content management system that allows creating single pages out of predefined blocks flexibly. For example I have a "product" block that is used to show producs on a page and it may appear numerous times on one page with different contents. But I also might wanna use it on different pages. Also I have simply generic blocks like multiple column text blocks (1 col, 2 col etc.) where I just want to insert this kind of structure into the page and enter any text. So I'm looking for a cms with someething like a building block / module concept for contents. I'm already searching the web but there are so many CMSs that I can't look into every one. So if anyone knows a solution that might be right for me, please tell me! Technology-wise it just has to run on Linux. If it's OpenSource / free that's great, but I might also pay for it, if it offers the features I want. Thanks for any hints in advance!

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• About Data Objects and DAO Design when using Hibernate

  - by X. Ma

  I'm hesitating between two designs of a database project using Hibernate. Design #1. (1) Create a general data provider interface, including a set of DAO interfaces and general data container classes. It hides the underneath implementation. A data provider implementation could access data in database, or an XML file, or a service, or something else. The user of a data provider does not to know about it. (2) Create a database library with Hibernate. This library implements the data provider interface in (1). The bad thing about Design #1 is that in order to hide the implementation details, I need to create two sets of data container classes. One in the general data provider interface - let's call them DPI-Objects, the other set is used in the database library, exclusively for entity/attribute mapping in Hibernate - let's call them H-Objects. In the DAO implementation, I need to read data from database to create H-Objects (via Hibernate) and then convert H-Objects into DPI-Objects. Design #2. Do not create a general data provider interface. Expose H-Objects directly to components that use the database lib. So the user of the database library needs to be aware of Hibernate. I like design #1 more, but I don't want to create two sets of data container classes. Is that the right way to hide H-Objects and other Hibernate implementation details from the user who uses the database-based data provider? Are there any drawbacks of Design #2? I will not implement other data provider in the new future, so should I just forget about the data provider interface and use Design #2? What do you think about this? Thanks for your time!

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• Is this an example of LINQ-to-SQL?

  - by Edward Tanguay

  I made a little WPF application with a SQL CE database. I built the following code with LINQ to get data out of the database, which was surprisingly easy. So I thought "this must be LINQ-to-SQL". Then I did "add item" and added a "LINQ-to-SQL classes" .dbml file, dragged my table onto the Object Relational Designer but it said, "The selected object uses an unsupported data provider." So then I questioned whether or not the following code actually is LINQ-to-SQL, since it indeed allows me to access data from my SQL CE database file, yet officially "LINQ-to-SQL" seems to be unsupported for SQL CE. So is the following "LINQ-to-SQL" or not? using System.Linq; using System.Data.Linq; using System.Data.Linq.Mapping; using System.Windows; namespace TestLinq22 { public partial class Window1 : Window { public Window1() { InitializeComponent(); MainDB db = new MainDB(@"Data Source=App_Data\Main.sdf"); var customers = from c in db.Customers select new {c.FirstName, c.LastName}; TheListBox.ItemsSource = customers; } } [Database(Name = "MainDB")] public class MainDB : DataContext { public MainDB(string connection) : base(connection) { } public Table<Customers> Customers; } [Table(Name = "Customers")] public class Customers { [Column(DbType = "varchar(100)")] public string FirstName; [Column(DbType = "varchar(100)")] public string LastName; } }

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• matching an element's class to another element's ID, or *part* of another element's ID

  - by shecky

  hello again Such a simple concept but I'm struggling to express it ... apologies in advance for my verbosity. I have a container div with a class, e.g., ; I want to use that class to do two things: add a class (e.g., 'active') to the nav element whose ID matches the class of div#container (e.g., #nav-primary li# apples) add the same class to another element if part of this element's ID matches the class of #container (e.g., div#secondary-apples) I assume there's an .each() loop to check the primary nav's list items' IDs, and to check the div IDs of the secondary nav ... though the latter needs to have its prefix trimmed ... or should I say more simply if the secondary nav div IDs contain the class of div#container? I've tried a few variations of something like this: <script type="text/javascript"> $(document).ready(function() { $('#nav-primary li').each(function(){ var containerClass = $('#container').attr('class'); var secondaryID = $('#nav-primary li').attr('id'); // something like if ('#nav-primary li id' == (containerClass) { } // or should I first store a variable of the LI's ID and do something like this: if ( secondaryID == containerClass ) { } // and for the trickier part, how do I filter/trim the secondary nav div IDs, something like this: var secondaryNavID = $('#aux-left div[id ... something here to strip the 'secondary-' bit ... ]'); }); // end each }); // end doc.ready.func </script> The markup is, e.g.: ... ... ... ... ... ... ... Many thanks in advance for any suggestions, svs

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