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  • How do I create an encrypted file system inside a file?

    - by darent
    Recently i've found this interesting tutorial: http://flossstuff.wordpress.com/2011/08/07/using-a-file-as-a-storage-device/ It explains how to create an empty file, format it as ext4, and mount it as a device. I'd like to know if it can be created as an encrypted ext4 file system. I've tried using palimpsest (the disk utility found in System menu) to format the already created file system but it doesn't works as it detects the file system being used. If I try to unmount the file system, it won't work neither because it doesn't detect the device (since it's not a real device like a hardrive or a usb drive). So my question is, is there an option to create the file system encrypted from the begining? I've used these commands: Create an empty file 200Mb size: dd if=/dev/zero of=/path/to/file bs=1M count=200 Make it ext4: mkfs -t ext4 file Mount it in a folder inside my home: sudo mount -o loop file /path/to/mount_point Is there any way the mkfs command creates the ext4 encrypted asking for a decryption password? I'm planing to use this as a way to encrypt files inside Dropbox. Thanks for your time.

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  • Should I use an interface when methods are only similar?

    - by Joshua Harris
    I was posed with the idea of creating an object that checks if a point will collide with a line: public class PointAndLineSegmentCollisionDetector { public void Collides(Point p, LineSegment s) { // ... } } This made me think that if I decided to create a Box object, then I would need a PointAndBoxCollisionDetector and a LineSegmentAndBoxCollisionDetector. I might even realize that I should have a BoxAndBoxCollisionDetector and a LineSegmentAndLineSegmentCollisionDetector. And, when I add new objects that can collide I would need to add even more of these. But, they all have a Collides method, so everything I learned about abstraction is telling me, "Make an interface." public interface CollisionDetector { public void Collides(Spatial s1, Spatial s2); } But now I have a function that only detects some abstract class or interface that is used by Point, LineSegment, Box, etc.. So if I did this then each implementation would have to to a type check to make sure that the types are the appropriate type because the collision algorithm is different for each different type match up. Another solution could be this: public class CollisionDetector { public void Collides(Point p, LineSegment s) { ... } public void Collides(LineSegment s, Box b) { ... } public void Collides(Point p, Box b) { ... } // ... } But, this could end up being a huge class that seems unwieldy, although it would have simplicity in that it is only a bunch of Collide methods. This is similar to C#'s Convert class. Which is nice because it is large, but it is simple to understand how it works. This seems to be the better solution, but I thought I should open it for discussion as a wiki to get other opinions.

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  • Benefits of classic OOP over Go-like language

    - by tylerl
    I've been thinking a lot about language design and what elements would be necessary for an "ideal" programming language, and studying Google's Go has led me to question a lot of otherwise common knowledge. Specifically, Go seems to have all of the interesting benefits from object oriented programming without actually having any of the structure of an object oriented language. There are no classes, only structures; there is no class/structure inheritance -- only structure embedding. There aren't any hierarchies, no parent classes, no explicit interface implementations. Instead, type casting rules are based on a loose system similar to duck-typing, such that if a struct implements the necessary elements of a "Reader" or a "Request" or an "Encoding", then you can cast it and use it as one. Does such a system obsolete the concept of OOP? Or is there something about OOP as implemented in C++ and Java and C# that is inherently more capable, more maintainable, somehow more powerful that you have to give up when moving to a language like Go? What benefit do you have to give up to gain the simplicity that this new paradigm represents?

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  • Mocking concrete class - Not recommended

    - by Mik378
    I've just read an excerpt of "Growing Object-Oriented Software" book which explains some reasons why mocking concrete class is not recommended. Here some sample code of a unit-test for the MusicCentre class: public class MusicCentreTest { @Test public void startsCdPlayerAtTimeRequested() { final MutableTime scheduledTime = new MutableTime(); CdPlayer player = new CdPlayer() { @Override public void scheduleToStartAt(Time startTime) { scheduledTime.set(startTime); } } MusicCentre centre = new MusicCentre(player); centre.startMediaAt(LATER); assertEquals(LATER, scheduledTime.get()); } } And his first explanation: The problem with this approach is that it leaves the relationship between the objects implicit. I hope we've made clear by now that the intention of Test-Driven Development with Mock Objects is to discover relationships between objects. If I subclass, there's nothing in the domain code to make such a relationship visible, just methods on an object. This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I can't figure out exactly what he means when he says: This makes it harder to see if the service that supports this relationship might be relevant elsewhere and I'll have to do the analysis again next time I work with the class. I understand that the service corresponds to MusicCentre's method called startMediaAt. What does he mean by "elsewhere"? The complete excerpt is here: http://www.mockobjects.com/2007/04/test-smell-mocking-concrete-classes.html

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  • Composing programs from small simple pieces: OOP vs Functional Programming

    - by Jay Godse
    I started programming when imperative programming languages such as C were virtually the only game in town for paid gigs. I'm not a computer scientist by training so I was only exposed to Assembler and Pascal in school, and not Lisp or Prolog. Over the 1990s, Object-Oriented Programming (OOP) became more popular because one of the marketing memes for OOP was that complex programs could be composed of loosely coupled but well-defined, well-tested, cohesive, and reusable classes and objects. And in many cases that is quite true. Once I learned object-oriented programming my C programs became better because I structured them more like classes and objects. In the last few years (2008-2014) I have programmed in Ruby, an OOP language. However, Ruby has many functional programming (FP) features such as lambdas and procs, which enable a different style of programming using recursion, currying, lazy evaluation and the like. (Through ignorance I am at a loss to explain why these techniques are so great). Very recently, I have written code to use methods from the Ruby Enumerable library, such as map(), reduce(), and select(). Apparently this is a functional style of programming. I have found that using these methods significantly reduce code volume, and make my code easier to debug. Upon reading more about FP, one of the marketing claims made by advocates is that FP enables developers to compose programs out of small well-defined, well-tested, and reusable functions, which leads to less buggy code, and low code volume. QUESTIONS: Is the composition of complex program by using FP techniques contradictory to or complementary to composition of a complex program by using OOP techniques? In which situations is OOP more effective, and when is FP more effective? Is it possible to use both techniques in the same complex program? Do the techniques overlap or contradict each other?

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  • Data classes: getters and setters or different method design

    - by Frog
    I've been trying to design an interface for a data class I'm writing. This class stores styles for characters, for example whether the character is bold, italic or underlined. But also the font-size and the font-family. So it has different types of member variables. The easiest way to implement this would be to add getters and setters for every member variable, but this just feels wrong to me. It feels way more logical (and more OOP) to call style.format(BOLD, true) instead of style.setBold(true). So to use logical methods insteads of getters/setters. But I am facing two problems while implementing these methods: I would need a big switch statement with all member variables, since you can't access a variable by the contents of a string in C++. Moreover, you can't overload by return type, which means you can't write one getter like style.getFormatting(BOLD) (I know there are some tricks to do this, but these don't allow for parameters, which I would obviously need). However, if I would implement getters and setters, there are also issues. I would have to duplicate quite some code because styles can also have a parent styles, which means the getters have to look not only at the member variables of this style, but also at the variables of the parent styles. Because I wasn't able to figure out how to do this, I decided to ask a question a couple of weeks ago. See Object Oriented Programming: getters/setters or logical names. But in that question I didn't stress it would be just a data object and that I'm not making a text rendering engine, which was the reason one of the people that answered suggested I ask another question while making that clear (because his solution, the decorator pattern, isn't suitable for my problem). So please note that I'm not creating my own text rendering engine, I just use these classes to store data. Because I still haven't been able to find a solution to this problem I'd like to ask this question again: how would you design a styles class like this? And why would you do that? Thanks on forehand!

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  • How to REALLY start thinking in terms of objects?

    - by Mr Grieves
    I work with a team of developers who all have several years of experience with languages such as C# and Java. Most of them are young enough to have been shown OOP as a standard way to develop software in university and are very comfortable with concepts such as inheritance, abstraction, encapsulation and polymorphism. Yet, many of them, and I have to include myself, still tend to create classes which are meant to be used in a very functional fashion. The resulting software is often several smaller classes which correctly represent business objects which get passed through larger classes which only supply ways to modify and use those objects (functions). Large complex difficult-to-maintain classes named Manager are usually the result of such behaviour. I can see two theoretical reasons why people might write this type of code: It's easy to start thinking of everything in terms of the database Deep down, for me, a computer handling a web request feels more like a functional operation than an object oriented operation when you think about Request Handlers, Threads, Processes, CPU Cores and CPU operations... I want source code which is easy to read and easy to modify. I have seen excellent examples of OO code which meet these objectives. How can I start writing code like this? How I can I really start thinking in an object oriented fashion? How can I share such a mentality with my colleagues?

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  • How to implement isValid correctly?

    - by Songo
    I'm trying to provide a mechanism for validating my object like this: class SomeObject { private $_inputString; private $_errors=array(); public function __construct($inputString) { $this->_inputString = $inputString; } public function getErrors() { return $this->_errors; } public function isValid() { $isValid = preg_match("/Some regular expression here/", $this->_inputString); if($isValid==0){ $this->_errors[]= 'Error was found in the input'; } return $isValid==1; } } Then when I'm testing my code I'm doing it like this: $obj = new SomeObject('an INVALID input string'); $isValid = $obj->isValid(); $errors=$obj->getErrors(); $this->assertFalse($isValid); $this->assertNotEmpty($errors); Now the test passes correctly, but I noticed a design problem here. What if the user called $obj->getErrors() before calling $obj->isValid()? The test will fail because the user has to validate the object first before checking the error resulting from validation. I think this way the user depends on a sequence of action to work properly which I think is a bad thing because it exposes the internal behaviour of the class. How do I solve this problem? Should I tell the user explicitly to validate first? Where do I mention that? Should I change the way I validate? Is there a better solution for this? UPDATE: I'm still developing the class so changes are easy and renaming functions and refactoring them is possible.

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  • How to model an address type in DDD?

    - by Songo
    I have an User entity that has a Set of Address where Address is a value object: class User{ ... private Set<Address> addresses; ... public setAddresses(Set<Address> addresses){ //set all addresses as a batch } ... } A User can have a home address and a work address, so I should have something that acts as a look up in the database: tbl_address_type ------------------------------------------------ | address_type_id | address_type | ------------------------------------------------ | 1 | work | ------------------------------------------------ | 2 | home | ------------------------------------------------ and correspondingly tbl_address ------------------------------------------------------------------------------------- | address_id | address_description |address_type_id| user_id | ------------------------------------------------------------------------------------- | 1 | 123 main street | 1 | 100 | ------------------------------------------------------------------------------------- | 2 | 456 another street | 1 | 100 | ------------------------------------------------------------------------------------- | 3 | 789 long street | 2 | 200 | ------------------------------------------------------------------------------------- | 4 | 023 short street | 2 | 200 | ------------------------------------------------------------------------------------- Should the address type be modeled as an Entity or Value type? and Why? Is it OK for the Address Value object to hold a reference to the Entity AdressType (in case it was modeled as an entity)? Is this something feasible using Hibernate/NHibernate? If a user can change his home address, should I expose a User.updateHomeAddress(Address homeAddress) function on the User entity itself? How can I enforce that the client passes a Home address and not a work address in this case? (a sample implementation is most welcomed) If I want to get the User's home address via User.getHomeAddress() function, must I load the whole addresses array then loop it and check each for its type till I found the correct type then return it? Is there a more efficient way than this?

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  • Reading data in from file

    - by user667430
    Hi Here is link if you want to download application: Simple banking app Text file with data to read I am trying to create a simple banking application that reads in data from a text file. So far i have managed to read in all the customers which there are 20 of them. However when reading in the accounts and transactions stuff it only reads in 20 but there is alot more in the text file. Here is what i have so far. I think it has something to do with the nested for loop in the getNextCustomer method. using System; using System.Collections; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.IO; using System.Linq; using System.Text; using System.Windows.Forms; namespace e_SOFT_Banking { public partial class Form1 : Form { public static ArrayList bankDetails = new ArrayList(); public static ArrayList accDetails = new ArrayList(); public static ArrayList tranDetails = new ArrayList(); string inputDataFile = @"C:\e-SOFT_v1.txt"; const int numCustItems = 14; const int numAccItems = 7; const int numTransItems = 5; public Form1() { InitializeComponent(); setUpBank(); } private void btnShowData_Click_1(object sender, EventArgs e) { showListsOfCust(); } private void setUpBank() { readData(); } private void showListsOfCust() { listBox1.Items.Clear(); foreach (Customer c in bankDetails) listBox1.Items.Add(c.getCustomerNumber() + " " + c.getCustomerTitle() + " " + c.getFirstName() + " " + c.getInitials() + " " + c.getSurname() + " " + c.getDateOfBirth() + " " + c.getHouseNameNumber() + " " + c.getStreetName() + " " + c.getArea() + " " + c.getCityTown() + " " + c.getCounty() + " " + c.getPostcode() + " " + c.getPassword() + " " + c.getNumberAccounts()); foreach (Account a in accDetails) listBox1.Items.Add(a.getAccSort() + " " + a.getAccNumber() + " " + a.getAccNick() + " " + a.getAccDate() + " " + a.getAccCurBal() + " " + a.getAccOverDraft() + " " + a.getAccNumTrans()); foreach (Transaction t in tranDetails) listBox1.Items.Add(t.getDate() + " " + t.getType() + " " + t.getDescription() + " " + t.getAmount() + " " + t.getBalAfter()); } private void readData() { StreamReader readerIn = null; Transaction curTrans; Account curAcc; Customer curCust; bool anyMoreData; string[] customerData = new string[numCustItems]; string[] accountData = new string[numAccItems]; string[] transactionData = new string[numTransItems]; if (readOK(inputDataFile, ref readerIn)) { anyMoreData = getNextCustomer(readerIn, customerData, accountData, transactionData); while (anyMoreData == true) { curCust = new Customer(customerData[0], customerData[1], customerData[2], customerData[3], customerData[4], customerData[5], customerData[6], customerData[7], customerData[8], customerData[9], customerData[10], customerData[11], customerData[12], customerData[13]); curAcc = new Account(accountData[0], accountData[1], accountData[2], accountData[3], accountData[4], accountData[5], accountData[6]); curTrans = new Transaction(transactionData[0], transactionData[1], transactionData[2], transactionData[3], transactionData[4]); bankDetails.Add(curCust); accDetails.Add(curAcc); tranDetails.Add(curTrans); anyMoreData = getNextCustomer(readerIn, customerData, accountData, transactionData); } if (readerIn != null) readerIn.Close(); } } private bool getNextCustomer(StreamReader inNext, string[] nextCustomerData, string[] nextAccountData, string[] nextTransactionData) { string nextLine; int numCItems = nextCustomerData.Count(); int numAItems = nextAccountData.Count(); int numTItems = nextTransactionData.Count(); for (int i = 0; i < numCItems; i++) { nextLine = inNext.ReadLine(); if (nextLine != null) { nextCustomerData[i] = nextLine; if (i == 13) { int cItems = Convert.ToInt32(nextCustomerData[13]); for (int q = 0; q < cItems; q++) { for (int a = 0; a < numAItems; a++) { nextLine = inNext.ReadLine(); nextAccountData[a] = nextLine; if (a == 6) { int aItems = Convert.ToInt32(nextAccountData[6]); for (int w = 0; w < aItems; w++) { for (int t = 0; t < numTItems; t++) { nextLine = inNext.ReadLine(); nextTransactionData[t] = nextLine; } } } } } } } else return false; } return true; } private bool readOK(string readFile, ref StreamReader readerIn) { try { readerIn = new StreamReader(readFile); return true; } catch (FileNotFoundException notFound) { MessageBox.Show("ERROR Opening file (when reading data in)" + " - File could not be found.\n" + notFound.Message); return false; } catch (Exception e) { MessageBox.Show("ERROR Opening File (when reading data in)" + "- Operation failed.\n" + e.Message); return false; } } } } I also have three classes one for customers, one for accounts and one for transactions, which follow in that order. using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace e_SOFT_Banking { class Customer { private string customerNumber; private string customerTitle; private string firstName; private string initials; //not required - defaults to null private string surname; private string dateOfBirth; private string houseNameNumber; private string streetName; private string area; //not required - defaults to null private string cityTown; private string county; private string postcode; private string password; private int numberAccounts; public Customer(string theCustomerNumber, string theCustomerTitle, string theFirstName, string theInitials, string theSurname, string theDateOfBirth, string theHouseNameNumber, string theStreetName, string theArea, string theCityTown, string theCounty, string thePostcode, string thePassword, string theNumberAccounts) { customerNumber = theCustomerNumber; customerTitle = theCustomerTitle; firstName = theFirstName; initials = theInitials; surname = theSurname; dateOfBirth = theDateOfBirth; houseNameNumber = theHouseNameNumber; streetName = theStreetName; area = theArea; cityTown = theCityTown; county = theCounty; postcode = thePostcode; password = thePassword; setNumberAccounts(theNumberAccounts); } public string getCustomerNumber() { return customerNumber; } public string getCustomerTitle() { return customerTitle; } public string getFirstName() { return firstName; } public string getInitials() { return initials; } public string getSurname() { return surname; } public string getDateOfBirth() { return dateOfBirth; } public string getHouseNameNumber() { return houseNameNumber; } public string getStreetName() { return streetName; } public string getArea() { return area; } public string getCityTown() { return cityTown; } public string getCounty() { return county; } public string getPostcode() { return postcode; } public string getPassword() { return password; } public int getNumberAccounts() { return numberAccounts; } public void setCustomerNumber(string inCustomerNumber) { customerNumber = inCustomerNumber; } public void setCustomerTitle(string inCustomerTitle) { customerTitle = inCustomerTitle; } public void setFirstName(string inFirstName) { firstName = inFirstName; } public void setInitials(string inInitials) { initials = inInitials; } public void setSurname(string inSurname) { surname = inSurname; } public void setDateOfBirth(string inDateOfBirth) { dateOfBirth = inDateOfBirth; } public void setHouseNameNumber(string inHouseNameNumber) { houseNameNumber = inHouseNameNumber; } public void setStreetName(string inStreetName) { streetName = inStreetName; } public void setArea(string inArea) { area = inArea; } public void setCityTown(string inCityTown) { cityTown = inCityTown; } public void setCounty(string inCounty) { county = inCounty; } public void setPostcode(string inPostcode) { postcode = inPostcode; } public void setPassword(string inPassword) { password = inPassword; } public void setNumberAccounts(string inNumberAccounts) { try { numberAccounts = Convert.ToInt32(inNumberAccounts); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } } } Accounts: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace e_SOFT_Banking { class Account { private string accSort; private Int64 accNumber; private string accNick; private string accDate; //not required - defaults to null private double accCurBal; private double accOverDraft; private int accNumTrans; public Account(string theAccSort, string theAccNumber, string theAccNick, string theAccDate, string theAccCurBal, string theAccOverDraft, string theAccNumTrans) { accSort = theAccSort; setAccNumber(theAccNumber); accNick = theAccNick; accDate = theAccDate; setAccCurBal(theAccCurBal); setAccOverDraft(theAccOverDraft); setAccNumTrans(theAccNumTrans); } public string getAccSort() { return accSort; } public long getAccNumber() { return accNumber; } public string getAccNick() { return accNick; } public string getAccDate() { return accDate; } public double getAccCurBal() { return accCurBal; } public double getAccOverDraft() { return accOverDraft; } public int getAccNumTrans() { return accNumTrans; } public void setAccSort(string inAccSort) { accSort = inAccSort; } public void setAccNumber(string inAccNumber) { try { accNumber = Convert.ToInt64(inAccNumber); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } public void setAccNick(string inAccNick) { accNick = inAccNick; } public void setAccDate(string inAccDate) { accDate = inAccDate; } public void setAccCurBal(string inAccCurBal) { try { accCurBal = Convert.ToDouble(inAccCurBal); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } public void setAccOverDraft(string inAccOverDraft) { try { accOverDraft = Convert.ToDouble(inAccOverDraft); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } public void setAccNumTrans(string inAccNumTrans) { try { accNumTrans = Convert.ToInt32(inAccNumTrans); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } } } Transactions: using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace e_SOFT_Banking { class Transaction { private string date; private string type; private string description; private double amount; //not required - defaults to null private double balAfter; public Transaction(string theDate, string theType, string theDescription, string theAmount, string theBalAfter) { date = theDate; type = theType; description = theDescription; setAmount(theAmount); setBalAfter(theBalAfter); } public string getDate() { return date; } public string getType() { return type; } public string getDescription() { return description; } public double getAmount() { return amount; } public double getBalAfter() { return balAfter; } public void setDate(string inDate) { date = inDate; } public void setType(string inType) { type = inType; } public void setDescription(string inDescription) { description = inDescription; } public void setAmount(string inAmount) { try { amount = Convert.ToDouble(inAmount); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } public void setBalAfter(string inBalAfter) { try { balAfter = Convert.ToDouble(inBalAfter); } catch (FormatException invalidInput) { System.Windows.Forms.MessageBox.Show("ERROR" + invalidInput.Message + "Please enter a valid number"); } } } } Any help greatly appreciated.

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  • SQL SERVER – SSMS: Top Object and Batch Execution Statistics Reports

    - by Pinal Dave
    The month of June till mid of July has been the fever of sports. First, it was Wimbledon Tennis and then the Soccer fever was all over. There is a huge number of fan followers and it is great to see the level at which people sometimes worship these sports. Being an Indian, I cannot forget to mention the India tour of England later part of July. Following these sports and as the events unfold to the finals, there are a number of ways the statisticians can slice and dice the numbers. Cue from soccer I can surely say there is a team performance against another team and then there is individual member fairs against a particular opponent. Such statistics give us a fair idea to how a team in the past or in the recent past has fared against each other, head-to-head stats during World cup and during other neutral venue games. All these statistics are just pointers. In reality, they don’t reflect the calibre of the current team because the individuals who performed in each of these games are totally different (Typical example being the Brazil Vs Germany semi-final match in FIFA 2014). So at times these numbers are misleading. It is worth investigating and get the next level information. Similar to these statistics, SQL Server Management studio is also equipped with a number of reports like a) Object Execution Statistics report and b) Batch Execution Statistics reports. As discussed in the example, the team scorecard is like the Batch Execution statistics and individual stats is like Object Level statistics. The analogy can be taken only this far, trust me there is no correlation between SQL Server functioning and playing sports – It is like I think about diet all the time except while I am eating. Performance – Batch Execution Statistics Let us view the first report which can be invoked from Server Node -> Reports -> Standard Reports -> Performance – Batch Execution Statistics. Most of the values that are displayed in this report come from the DMVs sys.dm_exec_query_stats and sys.dm_exec_sql_text(sql_handle). This report contains 3 distinctive sections as outline below.   Section 1: This is a graphical bar graph representation of Average CPU Time, Average Logical reads and Average Logical Writes for individual batches. The Batch numbers are indicative and the details of individual batch is available in section 3 (detailed below). Section 2: This represents a Pie chart of all the batches by Total CPU Time (%) and Total Logical IO (%) by batches. This graphical representation tells us which batch consumed the highest CPU and IO since the server started, provided plan is available in the cache. Section 3: This is the section where we can find the SQL statements associated with each of the batch Numbers. This also gives us the details of Average CPU / Average Logical Reads and Average Logical Writes in the system for the given batch with object details. Expanding the rows, I will also get the # Executions and # Plans Generated for each of the queries. Performance – Object Execution Statistics The second report worth a look is Object Execution statistics. This is a similar report as the previous but turned on its head by SQL Server Objects. The report has 3 areas to look as above. Section 1 gives the Average CPU, Average IO bar charts for specific objects. The section 2 is a graphical representation of Total CPU by objects and Total Logical IO by objects. The final section details the various objects in detail with the Avg. CPU, IO and other details which are self-explanatory. At a high-level both the reports are based on queries on two DMVs (sys.dm_exec_query_stats and sys.dm_exec_sql_text) and it builds values based on calculations using columns in them: SELECT * FROM    sys.dm_exec_query_stats s1 CROSS APPLY sys.dm_exec_sql_text(sql_handle) AS s2 WHERE   s2.objectid IS NOT NULL AND DB_NAME(s2.dbid) IS NOT NULL ORDER BY  s1.sql_handle; This is one of the simplest form of reports and in future blogs we will look at more complex reports. I truly hope that these reports can give DBAs and developers a hint about what is the possible performance tuning area. As a closing point I must emphasize that all above reports pick up data from the plan cache. If a particular query has consumed a lot of resources earlier, but plan is not available in the cache, none of the above reports would show that bad query. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: SQL, SQL Authority, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, T SQL Tagged: SQL Reports

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  • Advice on designing a robust program to handle a large library of meta-information & programs

    - by Sam Bryant
    So this might be overly vague, but here it is anyway I'm not really looking for a specific answer, but rather general design principles or direction towards resources that deal with problems like this. It's one of my first large-scale applications, and I would like to do it right. Brief Explanation My basic problem is that I have to write an application that handles a large library of meta-data, can easily modify the meta-data on-the-fly, is robust with respect to crashing, and is very efficient. (Sorta like the design parameters of iTunes, although sometimes iTunes performs more poorly than I would like). If you don't want to read the details, you can skip the rest Long Explanation Specifically I am writing a program that creates a library of image files and meta-data about these files. There is a list of tags that may or may not apply to each image. The program needs to be able to add new images, new tags, assign tags to images, and detect duplicate images, all while operating. The program contains an image Viewer which has tagging operations. The idea is that if a given image A is viewed while the library has tags T1, T2, and T3, then that image will have boolean flags for each of those tags (depending on whether the user tagged that image while it was open in the Viewer). However, prior to being viewed in the Viewer, image A would have no value for tags T1, T2, and T3. Instead it would have a "dirty" flag indicating that it is unknown whether or not A has these tags or not. The program can introduce new tags at any time (which would automatically set all images to "dirty" with respect to this new tag) This program must be fast. It must be easily able to pull up a list of images with or without a certain tag as well as images which are "dirty" with respect to a tag. It has to be crash-safe, in that if it suddenly crashes, all of the tagging information done in that session is not lost (though perhaps it's okay to loose some of it) Finally, it has to work with a lot of images (10,000) I am a fairly experienced programmer, but I have never tried to write a program with such demanding needs and I have never worked with databases. With respect to the meta-data storage, there seem to be a few design choices: Choice 1: Invidual meta-data vs centralized meta-data Individual Meta-Data: have a separate meta-data file for each image. This way, as soon as you change the meta-data for an image, it can be written to the hard disk, without having to rewrite the information for all of the other images. Centralized Meta-Data: Have a single file to hold the meta-data for every file. This would probably require meta-data writes in intervals as opposed to after every change. The benefit here is that you could keep a centralized list of all images with a given tag, ect, making the task of pulling up all images with a given tag very efficient

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  • Does OO, TDD, and Refactoring to Smaller Functions affect Speed of Code?

    - by Dennis
    In Computer Science field, I have noticed a notable shift in thinking when it comes to programming. The advice as it stands now is write smaller, more testable code refactor existing code into smaller and smaller chunks of code until most of your methods/functions are just a few lines long write functions that only do one thing (which makes them smaller again) This is a change compared to the "old" or "bad" code practices where you have methods spanning 2500 lines, and big classes doing everything. My question is this: when it call comes down to machine code, to 1s and 0s, to assembly instructions, should I be at all concerned that my class-separated code with variety of small-to-tiny functions generates too much extra overhead? While I am not exactly familiar with how OO code and function calls are handled in ASM in the end, I do have some idea. I assume that each extra function call, object call, or include call (in some languages), generate an extra set of instructions, thereby increasing code's volume and adding various overhead, without adding actual "useful" code. I also imagine that good optimizations can be done to ASM before it is actually ran on the hardware, but that optimization can only do so much too. Hence, my question -- how much overhead (in space and speed) does well-separated code (split up across hundreds of files, classes, and methods) actually introduce compared to having "one big method that contains everything", due to this overhead? UPDATE for clarity: I am assuming that adding more and more functions and more and more objects and classes in a code will result in more and more parameter passing between smaller code pieces. It was said somewhere (quote TBD) that up to 70% of all code is made up of ASM's MOV instruction - loading CPU registers with proper variables, not the actual computation being done. In my case, you load up CPU's time with PUSH/POP instructions to provide linkage and parameter passing between various pieces of code. The smaller you make your pieces of code, the more overhead "linkage" is required. I am concerned that this linkage adds to software bloat and slow-down and I am wondering if I should be concerned about this, and how much, if any at all, because current and future generations of programmers who are building software for the next century, will have to live with and consume software built using these practices. UPDATE: Multiple files I am writing new code now that is slowly replacing old code. In particular I've noted that one of the old classes was a ~3000 line file (as mentioned earlier). Now it is becoming a set of 15-20 files located across various directories, including test files and not including PHP framework I am using to bind some things together. More files are coming as well. When it comes to disk I/O, loading multiple files is slower than loading one large file. Of course not all files are loaded, they are loaded as needed, and disk caching and memory caching options exist, and yet still I believe that loading multiple files takes more processing than loading a single file into memory. I am adding that to my concern.

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  • Excel 2007 file writer in C# results in a corrupt file

    - by Martin
    Hi, I am using a BinaryReader to read an Excel 2007 file from an Exchange mailbox using a OWA, the file is then written to disk using a BinaryWriter. My problem is that the two files don't match when the writer finishes. Worse still Excel 2007 won't open the writen file. Previously Excel 2003 has had no problem with the solution below. And Excel 2007 doesn't have an issue if the file is an Excel 2003 format file, only if the file format is Excel 2007 (*.xlsx). BinaryReader: using(System.IO.Stream stream = resource.GetInputStream(attachedFiles[k].Address)) { using(System.IO.BinaryReader br = new System.IO.BinaryReader(stream)) { attachment.Data = new byte[attachedFiles[k].Size]; int bufPosn=0, len=0; while ((len = br.Read( attachment.Data, bufPosn, attachment.Data.Length-bufPosn )) > 0) { bufPosn += len; } br.Close(); } } BinaryWriter: FileStream fs = new FileStream(fileName, FileMode.Create); BinaryWriter binWriter = new BinaryWriter(fs); binWriter.Write( content, 0, content.Length ); binWriter.Close(); fs.Close(); Suggestions gratfully received.

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  • How to save a picture to a file?

    - by Peter vdL
    I'm trying to use a standard Intent that will take a picture, then allow approval or retake. Then I want to save the picture into a file. Here's the Intent I am using: Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE ); startActivityForResult( intent, 22 ); The docs at http://developer.android.com/reference/android/provider/MediaStore.html#ACTION_IMAGE_CAPTURE say "The caller may pass an extra EXTRA_OUTPUT to control where this image will be written. If the EXTRA_OUTPUT is not present, then a small sized image is returned as a Bitmap object in the extra field. If the EXTRA_OUTPUT is present, then the full-sized image will be written to the Uri value of EXTRA_OUTPUT." I don't pass extra output, I hope to get a Bitmap object in the extra field of the Intent passed into onActivityResult() (for this request). So where/how do you extract it? Intent has a getExtras(), but that returns a Bundle, and Bundle wants a key string to give you something back. What do you invoke on the Intent to extract the bitmap?

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  • batch file to merge .js files from subfolders into one combined file

    - by Andrew Johns
    I'm struggling to get this to work. Plenty of examples on the web, but they all do something just slightly different to what I'm aiming to do, and every time I think I can solve it, I get hit by an error that means nothing to me. After giving up on the JSLint.VS plugin, I'm attempting to create a batch file that I can call from a Visual Studio build event, or perhaps from cruise control, which will generate JSLint warnings for a project. The final goal is to get a combined js file that I can pass to jslint, using: cscript jslint.js < tmp.js which would validate that my scripts are ready to be combined into one file for use in a js minifier, or output a bunch of errors using standard output. but the js files that would make up tmp.js are likely to be in multiple subfolders in the project, e.g: D:\_projects\trunk\web\projectname\js\somefile.debug.js D:\_projects\trunk\web\projectname\js\jquery\plugins\jquery.plugin.js The ideal solution would be to be able to call a batch file along the lines of: jslint.bat %ProjectPath% and this would then combine all the js files within the project into one temp js file. This way I would have flexibility in which project was being passed to the batch file. I've been trying to make this work with copy, xcopy, type, and echo, and using a for do loop, with dir /s etc, to make it do what I want, but whatever I try I get an error.

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  • Accessing an excel file throws OleDbException but keeps handle on file

    - by Jonn
    Really odd that I'd get an oledbexception but turns out that the file's handle is still with the original file. I've been searching through google and keep finding the same problem but no solutions. Connection String: "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + filePath + ";" + "Extended Properties=Excel 8.0;"; Note that it works on every other file except a particular excel file. Exception: System.Data.OleDb.OleDbException: No error information available: E_UNEXPECTED(0x8000FFFF). And then I have exception handling like this: try { IEnumerable<string> worksheetNames = GetWorkbookWorksheetNames(connString); DataSet ds; foreach (string worksheetName in worksheetNames) { OleDbDataAdapter dataAdapter = new OleDbDataAdapter("SELECT * FROM [" + worksheetName + "]", connString); ds = new DataSet(); dataAdapter.Fill(ds, "ExcelInfo"); DataTable dt = ds.Tables["ExcelInfo"]; entityList.AddRange(GetDataFromDataTable(dt, worksheetName)); } } catch (OleDbException ex) { File.Move(filePath, filePath + ".invalidFormat.xls"); } Has anyone else encountered this behavior? And I'm not sure how to handle an error that keeps the handle on the file I'm supposed to process. It sort of freezes everything in place.

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  • What does 'postMessage()' do when called on an object tag?

    - by Stephano
    I was recently searching for a way to call the print function on a PDF I was displaying in adobe air. I solved this problem with a little help from this fellow, and by calling postMessage on my PDF like so: //this is the HTML I use to view my PDF <object id="PDFObj" data="test.pdf" type="application/pdf"/> ... //this actionscript lives in my air app var pdfObj:Object = htmlLoader.window.document.getElementById("PDFObj"); pdfObj.postMessage([message]); I've tried this in JavaScript as well, just to be sure it wasn't adobe sneaking in and helping me out... var obj = document.getElementById("PDFObj"); obj.postMessage([message]); Works well in JavaScript and in ActionScript. I looked up what the MDC had to say about postMessage, but all I found was window.postMessage. Now, the code works like a charm, and postMessage magically sends my message to my PDF's embedded JavaScript. However, I'm still not sure how I'm doing this. Any ideas?

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  • Trouble with object injection in Spring.Net

    - by Abdel Olakara
    Hi all, I have a issue with my Spring.Net configuration where its not injecting an object. I have a CommService to which an object named GeneralEmail is injected to. Here is the configuration: <!-- GeneralMail Object --> <object id="GeneralMailObject" type="CommUtil.Email.GeneralEmail, CommUtil"> <constructor-arg name="host" value="xxxxx.com"/> <constructor-arg name="port" value="25"/> <constructor-arg name="user" value="[email protected]"/> <constructor-arg name="password" value="xxxxx"/> <constructor-arg name="template" value="xxxxx"/> </object> <!-- Communication Service --> <object id="CommServiceObject" type="TApp.Code.Services.CommService, TApp"> <property name="emailService" ref="GeneralMailObject" /> </object> The communication service object is again injected to many other aspx pages & service. In one scenario, I need to call the commnucation service from an static WebMethod. I try doing: CommService cso = new CommService(); But when i try to get the emailService object, its null! why didn't the spring inject the GeneralMail object into my cso object? What am I doing wrong and how do I access the object from spring container. Thanks in advance for the suggestions and solutions. Reagrds, Abdel Olakara

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  • For each <item> in CheckedListBox. <item> returns as Object and not as Control

    - by Tivie
    Hello there. I have a CheckedListBox previously populated. I want to loop with a "for each / next" through all items in the CheckedListBox and do a lot of "stuff" with each iteration element of the checkedlistbox. example code: For Each item In CheckedListBox1.Items If item.Checked = True Then 'do stuff like item.BackColor = Color.Blue Else 'do other stuff item.BackColor = Color.Brown End If Next the problem is that is an 'Object' type and not a 'Control' type. If I force the iteration var As CheckBox, it throws an InvalidCastException saying that type 'System.String' can't be associated with type 'System.Windows.Forms.CheckBox' I know I can easily work around using for i=0 to CheckedListBox.Items.Count - 1 but I want to use a for each /next loop since I have a lot of code in that loop (and With can't be used) and always poiting directly to the object is something I wish to avoid and I really need the code to be as simple as possible. I actually spent one afternoon looking for this but couldn't find any answer. If someone could be kind enough to enlight me in this, it would be extremely appreciated. Best regards

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  • Google App Engine how to get an object from the servlet ?

    - by Frank
    I have the following class objects in Google App Engine's dadastore, I can see them from the "Datastore Viewer " : import javax.jdo.annotations.IdGeneratorStrategy; import javax.jdo.annotations.IdentityType; import javax.jdo.annotations.PersistenceCapable; import javax.jdo.annotations.Persistent; import javax.jdo.annotations.PrimaryKey; @PersistenceCapable(identityType=IdentityType.APPLICATION) public class Contact_Info_Entry implements Serializable { @PrimaryKey @Persistent(valueStrategy=IdGeneratorStrategy.IDENTITY) Long Id; public static final long serialVersionUID=26362862L; String Contact_Id="",First_Name="",Last_Name="",Company_Name="",Branch_Name="",Address_1="",Address_2="",City="",State="",Zip="",Country=""; double D_1,D_2; boolean B_1,B_2; Vector<String> A_Vector=new Vector<String>(); public Contact_Info_Entry() { } ...... } How can my java applications get the object from a servlet url ? For instance if have an instance of Contact_Info_Entry who's Contact_Id is "ABC-123", and my App Id is : nm-java When my java program accesses the url : "http://nm-java.appspot.com/Check_Contact_Info?Contact_Id=ABC-123 How will the Check_Contact_Info servlet get the object from datastore and return it to my app ? public class Check_Contact_Info_Servlet extends HttpServlet { static boolean Debug=true; public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException { } ... protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException { doGet(request,response); } } Frank

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  • Pass a variable from the source file to an included file in PHP

    - by Alpha1
    For my website I want to store the general format of the site in a single PHP file in a single location, and each of the different pages content in the local location of the page. I then want to pass the title and content address to the included file via a variable. However I can't get the included format file to read the variables storing the title and content data. AKA, the called file for the individual page would be: <?php $title = 'Some Title'; $source_file = 'content.php'; readfile('http:...../format.php'); ?> The format file would be: <html> ... <title> <?php echo $title; ?> </title> ... <?php include($source_file); ?> ... I recall reading somewhere I need to include something to get the variables at the start of the format file, however I can't remember what it is or find where I found that information.

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  • Why junit ComparisonFailure is not used by assertEquals(Object, Object) ?

    - by Philippe Blayo
    In Junit 4, do you see any drawback to throw a ComparisonFailure instead of an AssertionError when assertEquals(Object, Object) fails ? assertEquals(Object, Object) throws a ComparisonFailure if both expected and actual are String an AssertionError if either is not a String @Test(expected=ComparisonFailure.class ) public void twoString() { assertEquals("a String", "another String"); } @Test(expected=AssertionError.class ) public void oneString() { assertEquals("a String", new Object()); } The two reasons why I ask the question: ComparisonFailure provide far more readable way to spot the differences in dialog box of eclipse or Intellij IDEA (FEST-Assert throws this exception) Junit 4 already use String.valueOf(Object) to build message "expected ... but was ..." (format method invoqued by Assert.assertEquals(message, Object, Object) in junit-4.8.2): static String format(String message, Object expected, Object actual) { ... String expectedString= String.valueOf(expected); String actualString= String.valueOf(actual); if (expectedString.equals(actualString)) return formatted + "expected: " + formatClassAndValue(expected, expectedString) +" but was: " + formatClassAndValue(actual, actualString); else return formatted +"expected:<"+ expectedString +"> but was:<"+ actualString +">"; Isn't it possible in assertEquals(message, Object, Object) to replace fail(format(message, expected, actual)); by throw new ComparisonFailure(message, formatClassAndValue(expectedObject, expectedString), formatClassAndValue(actualObject, actualString)); Do you see any compatibility issue with other tool, any algorithmic problem with that... ?

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  • Android File Picker

    - by GuyNoir
    Is there a good solution for picking a file in an android application? I need the user to be able to browse their SD card for a file they would like to load. However, it cannot use an outside application (like andExplorer). It must stay contained inside my application. I saw one a while ago that's hosted on google code and used by the Gameboid, SNESoid and other similar emulators to pick roms. If any one can point me to that one that'd be just as great. Thanks!

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