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  • Java Magazine: Growing on Open

    - by Tori Wieldt
    The November/December issue of Java Magazine is now out, with several great Java stories, including: Growing on Open AgroSense provides an all-Java open source platform for sustainable farming and precision agriculture. An Engine for Big Data Hadoop uses Java for large-scale analytics. JavaFX in SpringStephen Chin shows you why to use the Spring framework on the client. JCP Executive Q&A: Mike MilinkovichThe Eclipse Foundation’s executive director assesses the state of Java and the JCP. Exploring Lambda Expressions for the Java Language and the JVMBen Evans, Martijn Verburg, and Trisha Gee help you get ready for lambda expressions in Java SE 8. Get Started with Java SE for Embedded Devices on Raspberry PiWe walk you through getting Linux and Java SE for Embedded Devices to run on the Raspberry Pi in less than an hour. Java NationGet the news from JavaOne 2012 in San Francisco. Java Magazine is a bi-monthly online publication. It includes technical articles on the Java language and platform; Java innovations and innovators; JUG and JCP news; Java events; links to online Java communities; and videos and multimedia demos. Subscriptions are free. Do you have feedback about Java Magazine? Send a tweet to @oraclejavamag.

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  • Stylecop 4.7.36.0 is out!

    - by TATWORTH
    Stylecop 4.7.36.0 has been released at http://stylecop.codeplex.com/releases/view/79972This is an update to coincide with the latest ReSharper. The full fix list is:4.7.36.0 (508dbac00ffc)=======================Fix for 7344. Don't throw 1126 inside default expressions.Fix for 7371. Compare Namespace parts using the CurrentCulture and not InvariantCulture.Fix for 7386. Don't throw casing violations for filed names in languages that do not support case (like Chinese). Added new tests.fix for 7380. Catch Exception caused by CRM Toolkit.Update ReSharper 7.0 dependency to 7.0.1 (7.0.1098.2760)Fix for 7358. Use the RuleId in the call to MSBuild Logging.Fix for 7348. Update suggestion text for constructors.Fix for 7364. Don't throw 1126 for New Array Expressions.Fix for 7372. Throw 1126 inside catch blocks wasn't working. Add new tests.Fix for 7369. Await is allowed to be inside parenthesis. Add new tests.Fix testsCorrect styling issues.Fix for 7373. Typeparam violations were not being thrown in all cases. Added new tests.Fix for 7361. Rule 1120 was logging against the root element and so Suppressions wouldn't work. Fixed and added tests.Updating de-DE resources - from Michael Diermeier - thank you.Change for 7368. Add the violation count into the Task outputs.Fix for 7383. Fix for memory leak in plugins.Update environment to detect ReSharper 7Fix for 7378. Null reference exception from command line run in message output.Update release history.

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  • How to correct a junior, but encourage him to think for himself? [closed]

    - by Phil
    I am the lead of a small team where everyone has less than a year of software development experience. I wouldn't by any means call myself a software guru, but I have learned a few things in the few years that I've been writing software. When we do code reviews I do a fair bit of teaching and correcting mistakes. I will say things like "This is overly complex and convoluted, and here's why," or "What do you think about moving this method into a separate class?" I am extra careful to communicate that if they have questions or dissenting opinions, that's ok and we need to discuss. Every time I correct someone, I ask "What do you think?" or something similar. However they rarely if ever disagree or ask why. And lately I've been noticing more blatant signs that they are blindly agreeing with my statements and not forming opinions of their own. I need a team who can learn to do things right autonomously, not just follow instructions. How does one correct a junior developer, but still encourage him to think for himself? Edit: Here's an example of one of these obvious signs that they're not forming their own opinions: Me: I like your idea of creating an extension method, but I don't like how you passed a large complex lambda as a parameter. The lambda forces others to know too much about the method's implementation. Junior (after misunderstanding me): Yes, I totally agree. We should not use extension methods here because they force other developers to know too much about the implementation. There was a misunderstanding, and that has been dealt with. But there was not even an OUNCE of logic in his statement! He thought he was regurgitating my logic back to me, thinking it would make sense when really he had no clue why he was saying it.

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  • Replacement Text Syntax for JavaScript’s String.replace()

    - by Jan Goyvaerts
    A RegexBuddy user told me that he couldn’t easily find a detailed explanation of the replacement text syntax supported by the String.replace() function in JavaScript. I had to admin that my own web page about JavaScript’s regular expression support was also lacking. I’ve now added a new Replacement Syntax section that has all the details. I’ll summarize it here: $1: Text matched by the first capturing group or the literal text $1 if the regex has no capturing groups. $99: Text matched by the 99th capturing group if the regex has 99 or more groups. Text matched by the 9th capturing group followed by a literal 9 if the regex has 9 or more but less than 99 groups. The literal text $99 if the regex has fewer than 9 groups. $+: Text matched by the highest-numbered capturing group. Replaced with nothing if the highest-numbered group didn’t participate in the match. $&: Text matched by the entire regex. You cannot use $0 for this. $` (backtick): Text to the left of the regex match. $' (single quote): Text to the right of the regex match. $_: The entire subject string.

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  • Python 3.4 adds re.fullmatch()

    - by Jan Goyvaerts
    Python 3.4 does not bring any changes to its regular expression syntax compared to previous 3.x releases. It does add one new function to the re module called fullmatch(). This function takes a regular expression and a subject string as its parameters. It returns True if the regular expression can match the string entirely. It returns False if the string cannot be matched or if it can only be matched partially. This is useful when using a regular expression to validate user input. Do note that fullmatch() will return True if the subject string is the empty string and the regular expression can find zero-length matches. A zero-length match of a zero-length string is a complete match. So if you want to check whether the user entered a sequence of digits, use \d+ rather than \d* as the regex.

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  • Bug in Delphi XE RegularExpressions Unit

    - by Jan Goyvaerts
    Using the new RegularExpressions unit in Delphi XE, you can iterate over all the matches that a regex finds in a string like this: procedure TForm1.Button1Click(Sender: TObject); var RegEx: TRegEx; Match: TMatch; begin RegEx := TRegex.Create('\w+'); Match := RegEx.Match('One two three four'); while Match.Success do begin Memo1.Lines.Add(Match.Value); Match := Match.NextMatch; end end; Or you could save yourself two lines of code by using the static TRegEx.Match call: procedure TForm1.Button2Click(Sender: TObject); var Match: TMatch; begin Match := TRegEx.Match('One two three four', '\w+'); while Match.Success do begin Memo1.Lines.Add(Match.Value); Match := Match.NextMatch; end end; Unfortunately, due to a bug in the RegularExpressions unit, the static call doesn’t work. Depending on your exact code, you may get fewer matches or blank matches than you should, or your application may crash with an access violation. The RegularExpressions unit defines TRegEx and TMatch as records. That way you don’t have to explicitly create and destroy them. Internally, TRegEx uses TPerlRegEx to do the heavy lifting. TPerlRegEx is a class that needs to be created and destroyed like any other class. If you look at the TRegEx source code, you’ll notice that it uses an interface to destroy the TPerlRegEx instance when TRegEx goes out of scope. Interfaces are reference counted in Delphi, making them usable for automatic memory management. The bug is that TMatch and TGroupCollection also need the TPerlRegEx instance to do their work. TRegEx passes its TPerlRegEx instance to TMatch and TGroupCollection, but it does not pass the instance of the interface that is responsible for destroying TPerlRegEx. This is not a problem in our first code sample. TRegEx stays in scope until we’re done with TMatch. The interface is destroyed when Button1Click exits. In the second code sample, the static TRegEx.Match call creates a local variable of type TRegEx. This local variable goes out of scope when TRegEx.Match returns. Thus the reference count on the interface reaches zero and TPerlRegEx is destroyed when TRegEx.Match returns. When we call MatchAgain the TMatch record tries to use a TPerlRegEx instance that has already been destroyed. To fix this bug, delete or rename the two RegularExpressions.dcu files and copy RegularExpressions.pas into your source code folder. Make these changes to both the TMatch and TGroupCollection records in this unit: Declare FNotifier: IInterface; in the private section. Add the parameter ANotifier: IInterface; to the Create constructor. Assign FNotifier := ANotifier; in the constructor’s implementation. You also need to add the ANotifier: IInterface; parameter to the TMatchCollection.Create constructor. Now try to compile some code that uses the RegularExpressions unit. The compiler will flag all calls to TMatch.Create, TGroupCollection.Create and TMatchCollection.Create. Fix them by adding the ANotifier or FNotifier parameter, depending on whether ARegEx or FRegEx is being passed. With these fixes, the TPerlRegEx instance won’t be destroyed until the last TRegEx, TMatch, or TGroupCollection that uses it goes out of scope or is used with a different regular expression.

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  • Custom language - FOR loop in a clojure interpeter?

    - by Mark
    I have a basic interpreter in clojure. Now i need to implement for (initialisation; finish-test; loop-update) { statements } Implement a similar for-loop for the interpreted language. The pattern will be: (for variable-declarations end-test loop-update do statement) The variable-declarations will set up initial values for variables.The end-test returns a boolean, and the loop will end if end-test returns false. The statement is interpreted followed by the loop-update for each pass of the loop. Examples of use are: (run ’(for ((i 0)) (< i 10) (set i (+ 1 i)) do (println i))) (run ’(for ((i 0) (j 0)) (< i 10) (seq (set i (+ 1 i)) (set j (+ j (* 2 i)))) do (println j))) inside my interpreter. I will attach my interpreter code I got so far. Any help is appreciated. Interpreter (declare interpret make-env) ;; needed as language terms call out to 'interpret' (def do-trace false) ;; change to 'true' to show calls to 'interpret' ;; simple utilities (def third ; return third item in a list (fn [a-list] (second (rest a-list)))) (def fourth ; return fourth item in a list (fn [a-list] (third (rest a-list)))) (def run ; make it easy to test the interpreter (fn [e] (println "Processing: " e) (println "=> " (interpret e (make-env))))) ;; for the environment (def make-env (fn [] '())) (def add-var (fn [env var val] (cons (list var val) env))) (def lookup-var (fn [env var] (cond (empty? env) 'error (= (first (first env)) var) (second (first env)) :else (lookup-var (rest env) var)))) ;; for terms in language ;; -- define numbers (def is-number? (fn [expn] (number? expn))) (def interpret-number (fn [expn env] expn)) ;; -- define symbols (def is-symbol? (fn [expn] (symbol? expn))) (def interpret-symbol (fn [expn env] (lookup-var env expn))) ;; -- define boolean (def is-boolean? (fn [expn] (or (= expn 'true) (= expn 'false)))) (def interpret-boolean (fn [expn env] expn)) ;; -- define functions (def is-function? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'lambda (first expn))))) (def interpret-function ; keep function definitions as they are written (fn [expn env] expn)) ;; -- define addition (def is-plus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '+ (first expn))))) (def interpret-plus (fn [expn env] (+ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define subtraction (def is-minus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '- (first expn))))) (def interpret-minus (fn [expn env] (- (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define multiplication (def is-times? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '* (first expn))))) (def interpret-times (fn [expn env] (* (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define division (def is-divides? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '/ (first expn))))) (def interpret-divides (fn [expn env] (/ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define equals test (def is-equals? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '= (first expn))))) (def interpret-equals (fn [expn env] (= (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define greater-than test (def is-greater-than? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '> (first expn))))) (def interpret-greater-than (fn [expn env] (> (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define not (def is-not? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'not (first expn))))) (def interpret-not (fn [expn env] (not (interpret (second expn) env)))) ;; -- define or (def is-or? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'or (first expn))))) (def interpret-or (fn [expn env] (or (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define and (def is-and? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'and (first expn))))) (def interpret-and (fn [expn env] (and (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define print (def is-print? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'println (first expn))))) (def interpret-print (fn [expn env] (println (interpret (second expn) env)))) ;; -- define with (def is-with? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'with (first expn))))) (def interpret-with (fn [expn env] (interpret (third expn) (add-var env (first (second expn)) (interpret (second (second expn)) env))))) ;; -- define if (def is-if? (fn [expn] (and (list? expn) (= 4 (count expn)) (= 'if (first expn))))) (def interpret-if (fn [expn env] (cond (interpret (second expn) env) (interpret (third expn) env) :else (interpret (fourth expn) env)))) ;; -- define function-application (def is-function-application? (fn [expn env] (and (list? expn) (= 2 (count expn)) (is-function? (interpret (first expn) env))))) (def interpret-function-application (fn [expn env] (let [function (interpret (first expn) env)] (interpret (third function) (add-var env (first (second function)) (interpret (second expn) env)))))) ;; the interpreter itself (def interpret (fn [expn env] (cond do-trace (println "Interpret is processing: " expn)) (cond ; basic values (is-number? expn) (interpret-number expn env) (is-symbol? expn) (interpret-symbol expn env) (is-boolean? expn) (interpret-boolean expn env) (is-function? expn) (interpret-function expn env) ; built-in functions (is-plus? expn) (interpret-plus expn env) (is-minus? expn) (interpret-minus expn env) (is-times? expn) (interpret-times expn env) (is-divides? expn) (interpret-divides expn env) (is-equals? expn) (interpret-equals expn env) (is-greater-than? expn) (interpret-greater-than expn env) (is-not? expn) (interpret-not expn env) (is-or? expn) (interpret-or expn env) (is-and? expn) (interpret-and expn env) (is-print? expn) (interpret-print expn env) ; special syntax (is-with? expn) (interpret-with expn env) (is-if? expn) (interpret-if expn env) ; functions (is-function-application? expn env) (interpret-function-application expn env) :else 'error))) ;; tests of using environment (println "Environment tests:") (println (add-var (make-env) 'x 1)) (println (add-var (add-var (add-var (make-env) 'x 1) 'y 2) 'x 3)) (println (lookup-var '() 'x)) (println (lookup-var '((x 1)) 'x)) (println (lookup-var '((x 1) (y 2)) 'x)) (println (lookup-var '((x 1) (y 2)) 'y)) (println (lookup-var '((x 3) (y 2) (x 1)) 'x)) ;; examples of using interpreter (println "Interpreter examples:") (run '1) (run '2) (run '(+ 1 2)) (run '(/ (* (+ 4 5) (- 2 4)) 2)) (run '(with (x 1) x)) (run '(with (x 1) (with (y 2) (+ x y)))) (run '(with (x (+ 2 4)) x)) (run 'false) (run '(not false)) (run '(with (x true) (with (y false) (or x y)))) (run '(or (= 3 4) (> 4 3))) (run '(with (x 1) (if (= x 1) 2 3))) (run '(with (x 2) (if (= x 1) 2 3))) (run '((lambda (n) (* 2 n)) 4)) (run '(with (double (lambda (n) (* 2 n))) (double 4))) (run '(with (sum-to (lambda (n) (if (= n 0) 0 (+ n (sum-to (- n 1)))))) (sum-to 100))) (run '(with (x 1) (with (f (lambda (n) (+ n x))) (with (x 2) (println (f 3))))))

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  • C#: System.Lazy&lt;T&gt; and the Singleton Design Pattern

    - by James Michael Hare
    So we've all coded a Singleton at one time or another.  It's a really simple pattern and can be a slightly more elegant alternative to global variables.  Make no mistake, Singletons can be abused and are often over-used -- but occasionally you find a Singleton is the most elegant solution. For those of you not familiar with a Singleton, the basic Design Pattern is that a Singleton class is one where there is only ever one instance of the class created.  This means that constructors must be private to avoid users creating their own instances, and a static property (or method in languages without properties) is defined that returns a single static instance. 1: public class Singleton 2: { 3: // the single instance is defined in a static field 4: private static readonly Singleton _instance = new Singleton(); 5:  6: // constructor private so users can't instantiate on their own 7: private Singleton() 8: { 9: } 10:  11: // read-only property that returns the static field 12: public static Singleton Instance 13: { 14: get 15: { 16: return _instance; 17: } 18: } 19: } This is the most basic singleton, notice the key features: Static readonly field that contains the one and only instance. Constructor is private so it can only be called by the class itself. Static property that returns the single instance. Looks like it satisfies, right?  There's just one (potential) problem.  C# gives you no guarantee of when the static field _instance will be created.  This is because the C# standard simply states that classes (which are marked in the IL as BeforeFieldInit) can have their static fields initialized any time before the field is accessed.  This means that they may be initialized on first use, they may be initialized at some other time before, you can't be sure when. So what if you want to guarantee your instance is truly lazy.  That is, that it is only created on first call to Instance?  Well, there's a few ways to do this.  First we'll show the old ways, and then talk about how .Net 4.0's new System.Lazy<T> type can help make the lazy-Singleton cleaner. Obviously, we could take on the lazy construction ourselves, but being that our Singleton may be accessed by many different threads, we'd need to lock it down. 1: public class LazySingleton1 2: { 3: // lock for thread-safety laziness 4: private static readonly object _mutex = new object(); 5:  6: // static field to hold single instance 7: private static LazySingleton1 _instance = null; 8:  9: // property that does some locking and then creates on first call 10: public static LazySingleton1 Instance 11: { 12: get 13: { 14: if (_instance == null) 15: { 16: lock (_mutex) 17: { 18: if (_instance == null) 19: { 20: _instance = new LazySingleton1(); 21: } 22: } 23: } 24:  25: return _instance; 26: } 27: } 28:  29: private LazySingleton1() 30: { 31: } 32: } This is a standard double-check algorithm so that you don't lock if the instance has already been created.  However, because it's possible two threads can go through the first if at the same time the first time back in, you need to check again after the lock is acquired to avoid creating two instances. Pretty straightforward, but ugly as all heck.  Well, you could also take advantage of the C# standard's BeforeFieldInit and define your class with a static constructor.  It need not have a body, just the presence of the static constructor will remove the BeforeFieldInit attribute on the class and guarantee that no fields are initialized until the first static field, property, or method is called.   1: public class LazySingleton2 2: { 3: // because of the static constructor, this won't get created until first use 4: private static readonly LazySingleton2 _instance = new LazySingleton2(); 5:  6: // Returns the singleton instance using lazy-instantiation 7: public static LazySingleton2 Instance 8: { 9: get { return _instance; } 10: } 11:  12: // private to prevent direct instantiation 13: private LazySingleton2() 14: { 15: } 16:  17: // removes BeforeFieldInit on class so static fields not 18: // initialized before they are used 19: static LazySingleton2() 20: { 21: } 22: } Now, while this works perfectly, I hate it.  Why?  Because it's relying on a non-obvious trick of the IL to guarantee laziness.  Just looking at this code, you'd have no idea that it's doing what it's doing.  Worse yet, you may decide that the empty static constructor serves no purpose and delete it (which removes your lazy guarantee).  Worse-worse yet, they may alter the rules around BeforeFieldInit in the future which could change this. So, what do I propose instead?  .Net 4.0 adds the System.Lazy type which guarantees thread-safe lazy-construction.  Using System.Lazy<T>, we get: 1: public class LazySingleton3 2: { 3: // static holder for instance, need to use lambda to construct since constructor private 4: private static readonly Lazy<LazySingleton3> _instance 5: = new Lazy<LazySingleton3>(() => new LazySingleton3()); 6:  7: // private to prevent direct instantiation. 8: private LazySingleton3() 9: { 10: } 11:  12: // accessor for instance 13: public static LazySingleton3 Instance 14: { 15: get 16: { 17: return _instance.Value; 18: } 19: } 20: } Note, you need your lambda to call the private constructor as Lazy's default constructor can only call public constructors of the type passed in (which we can't have by definition of a Singleton).  But, because the lambda is defined inside our type, it has access to the private members so it's perfect. Note how the Lazy<T> makes it obvious what you're doing (lazy construction), instead of relying on an IL generation side-effect.  This way, it's more maintainable.  Lazy<T> has many other uses as well, obviously, but I really love how elegant and readable it makes the lazy Singleton.

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  • Creating Property Set Expression Trees In A Developer Friendly Way

    - by Paulo Morgado
    In a previous post I showed how to create expression trees to set properties on an object. The way I did it was not very developer friendly. It involved explicitly creating the necessary expressions because the compiler won’t generate expression trees with property or field set expressions. Recently someone contacted me the help develop some kind of command pattern framework that used developer friendly lambdas to generate property set expression trees. Simply putting, given this entity class: public class Person { public string Name { get; set; } } The person in question wanted to write code like this: var et = Set((Person p) => p.Name = "me"); Where et is the expression tree that represents the property assignment. So, if we can’t do this, let’s try the next best thing that is splitting retrieving the property information from the retrieving the value to assign o the property: var et = Set((Person p) => p.Name, () => "me"); And this is something that the compiler can handle. The implementation of Set receives an expression to retrieve the property information from and another expression the retrieve the value to assign to the property: public static Expression<Action<TEntity>> Set<TEntity, TValue>( Expression<Func<TEntity, TValue>> propertyGetExpression, Expression<Func<TValue>> valueExpression) The implementation of this method gets the property information form the body of the property get expression (propertyGetExpression) and the value expression (valueExpression) to build an assign expression and builds a lambda expression using the same parameter of the property get expression as its parameter: public static Expression<Action<TEntity>> Set<TEntity, TValue>( Expression<Func<TEntity, TValue>> propertyGetExpression, Expression<Func<TValue>> valueExpression) { var entityParameterExpression = (ParameterExpression)(((MemberExpression)(propertyGetExpression.Body)).Expression); return Expression.Lambda<Action<TEntity>>( Expression.Assign(propertyGetExpression.Body, valueExpression.Body), entityParameterExpression); } And now we can use the expression to translate to another context or just compile and use it: var et = Set((Person p) => p.Name, () => name); Console.WriteLine(person.Name); // Prints: p => (p.Name = “me”) var d = et.Compile(); d(person); Console.WriteLine(person.Name); // Prints: me It can even support closures: var et = Set((Person p) => p.Name, () => name); Console.WriteLine(person.Name); // Prints: p => (p.Name = value(<>c__DisplayClass0).name) var d = et.Compile(); name = "me"; d(person); Console.WriteLine(person.Name); // Prints: me name = "you"; d(person); Console.WriteLine(person.Name); // Prints: you Not so useful in the intended scenario (but still possible) is building an expression tree that receives the value to assign to the property as a parameter: public static Expression<Action<TEntity, TValue>> Set<TEntity, TValue>(Expression<Func<TEntity, TValue>> propertyGetExpression) { var entityParameterExpression = (ParameterExpression)(((MemberExpression)(propertyGetExpression.Body)).Expression); var valueParameterExpression = Expression.Parameter(typeof(TValue)); return Expression.Lambda<Action<TEntity, TValue>>( Expression.Assign(propertyGetExpression.Body, valueParameterExpression), entityParameterExpression, valueParameterExpression); } This new expression can be used like this: var et = Set((Person p) => p.Name); Console.WriteLine(person.Name); // Prints: (p, Param_0) => (p.Name = Param_0) var d = et.Compile(); d(person, "me"); Console.WriteLine(person.Name); // Prints: me d(person, "you"); Console.WriteLine(person.Name); // Prints: you The only caveat is that we need to be able to write code to read the property in order to write to it.

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  • WebSocket API 1.1 released!

    - by Pavel Bucek
    Its my please to announce that JSR 356 – Java API for WebSocket maintenance release ballot vote finished with majority of “yes” votes (actually, only one eligible voter did not vote, all other votes were “yeses”). New release is maintenance release and it addresses only one issue:  WEBSOCKET_SPEC-226. What changed in the 1.1? Version 1.1 is fully backwards compatible with version 1.0, there are only two methods added to javax.websocket.Session: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 /** * Register to handle to incoming messages in this conversation. A maximum of one message handler per * native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum * of one message handler to handle incoming text messages a maximum of one message handler for * handling incoming binary messages, and a maximum of one for handling incoming pong * messages. For further details of which message handlers handle which of the native websocket * message types please see {@link MessageHandler.Whole} and {@link MessageHandler.Partial}. * Adding more than one of any one type will result in a runtime exception. * * @param clazz   type of the message processed by message handler to be registered. * @param handler whole message handler to be added. * @throws IllegalStateException if there is already a MessageHandler registered for the same native *                               websocket message type as this handler. */ public void addMessageHandler(Class<T> clazz, MessageHandler.Whole<T> handler); /** * Register to handle to incoming messages in this conversation. A maximum of one message handler per * native websocket message type (text, binary, pong) may be added to each Session. I.e. a maximum * of one message handler to handle incoming text messages a maximum of one message handler for * handling incoming binary messages, and a maximum of one for handling incoming pong * messages. For further details of which message handlers handle which of the native websocket * message types please see {@link MessageHandler.Whole} and {@link MessageHandler.Partial}. * Adding more than one of any one type will result in a runtime exception. * * * @param clazz   type of the message processed by message handler to be registered. * @param handler partial message handler to be added. * @throws IllegalStateException if there is already a MessageHandler registered for the same native *                               websocket message type as this handler. */ public void addMessageHandler(Class<T> clazz, MessageHandler.Partial<T> handler); Why do we need to add those methods? Short and not precise version: to support Lambda expressions as MessageHandlers. Longer and slightly more precise explanation: old Session#addMessageHandler method (which is still there and works as it worked till now) does rely on getting the generic parameter during the runtime, which is not (always) possible. The unfortunate part is that it works for some common cases and the expert group did not catch this issue before 1.0 release because of that. The issue is really clearly visible when Lambdas are used as message handlers: 1 2 3 session.addMessageHandler(message -> { System.out.println("### Received: " + message); }); There is no way for the JSR 356 implementation to get the type of the used Lambda expression, thus this call will always result in an exception. Since all modern IDEs do recommend to use Lambda expressions when possible and MessageHandler interfaces are single method interfaces, it basically just scream “use Lambdas” all over the place but when you do that, the application will fail during runtime. Only solution we currently have is to explicitly provide the type of registered MessageHandler. (There might be another sometime in the future when generic type reification is introduced, but that is not going to happen soon enough). So the example above will then be: 1 2 3 session.addMessageHandler(String.class, message -> { System.out.println("### Received: " + message); }); and voila, it works. There are some limitations – you cannot do 1 List<String>.class , so you will need to encapsulate these types when you want to use them in MessageHandler implementation (something like “class MyType extends ArrayList<String>”). There is no better way how to solve this issue, because Java currently does not provide good way how to describe generic types. The api itself is available on maven central, look for javax.websocket:javax.websocket-api:1.1. The reference implementation is project Tyrus, which implements WebSocket API 1.1 from version 1.8.

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  • ROracle support for TimesTen In-Memory Database

    - by Sam Drake
    Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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  • ROracle support for TimesTen In-Memory Database

    - by Sherry LaMonica
    Today's guest post comes from Jason Feldhaus, a Consulting Member of Technical Staff in the TimesTen Database organization at Oracle.  He shares with us a sample session using ROracle with the TimesTen In-Memory database.  Beginning in version 1.1-4, ROracle includes support for the Oracle Times Ten In-Memory Database, version 11.2.2. TimesTen is a relational database providing very fast and high throughput through its memory-centric architecture.  TimesTen is designed for low latency, high-volume data, and event and transaction management. A TimesTen database resides entirely in memory, so no disk I/O is required for transactions and query operations. TimesTen is used in applications requiring very fast and predictable response time, such as real-time financial services trading applications and large web applications. TimesTen can be used as the database of record or as a relational cache database to Oracle Database. ROracle provides an interface between R and the database, providing the rich functionality of the R statistical programming environment using the SQL query language. ROracle uses the OCI libraries to handle database connections, providing much better performance than standard ODBC.The latest ROracle enhancements include: Support for Oracle TimesTen In-Memory Database Support for Date-Time using R's POSIXct/POSIXlt data types RAW, BLOB and BFILE data type support Option to specify number of rows per fetch operation Option to prefetch LOB data Break support using Ctrl-C Statement caching support Times Ten 11.2.2 contains enhanced support for analytics workloads and complex queries: Analytic functions: AVG, SUM, COUNT, MAX, MIN, DENSE_RANK, RANK, ROW_NUMBER, FIRST_VALUE and LAST_VALUE Analytic clauses: OVER PARTITION BY and OVER ORDER BY Multidimensional grouping operators: Grouping clauses: GROUP BY CUBE, GROUP BY ROLLUP, GROUP BY GROUPING SETS Grouping functions: GROUP, GROUPING_ID, GROUP_ID WITH clause, which allows repeated references to a named subquery block Aggregate expressions over DISTINCT expressions General expressions that return a character string in the source or a pattern within the LIKE predicate Ability to order nulls first or last in a sort result (NULLS FIRST or NULLS LAST in the ORDER BY clause) Note: Some functionality is only available with Oracle Exalytics, refer to the TimesTen product licensing document for details. Connecting to TimesTen is easy with ROracle. Simply install and load the ROracle package and load the driver. > install.packages("ROracle") > library(ROracle) Loading required package: DBI > drv <- dbDriver("Oracle") Once the ROracle package is installed, create a database connection object and connect to a TimesTen direct driver DSN as the OS user. > conn <- dbConnect(drv, username ="", password="", dbname = "localhost/SampleDb_1122:timesten_direct") You have the option to report the server type - Oracle or TimesTen? > print (paste ("Server type =", dbGetInfo (conn)$serverType)) [1] "Server type = TimesTen IMDB" To create tables in the database using R data frame objects, use the function dbWriteTable. In the following example we write the built-in iris data frame to TimesTen. The iris data set is a small example data set containing 150 rows and 5 columns. We include it here not to highlight performance, but so users can easily run this example in their R session. > dbWriteTable (conn, "IRIS", iris, overwrite=TRUE, ora.number=FALSE) [1] TRUE Verify that the newly created IRIS table is available in the database. To list the available tables and table columns in the database, use dbListTables and dbListFields, respectively. > dbListTables (conn) [1] "IRIS" > dbListFields (conn, "IRIS") [1] "SEPAL.LENGTH" "SEPAL.WIDTH" "PETAL.LENGTH" "PETAL.WIDTH" "SPECIES" To retrieve a summary of the data from the database we need to save the results to a local object. The following call saves the results of the query as a local R object, iris.summary. The ROracle function dbGetQuery is used to execute an arbitrary SQL statement against the database. When connected to TimesTen, the SQL statement is processed completely within main memory for the fastest response time. > iris.summary <- dbGetQuery(conn, 'SELECT SPECIES, AVG ("SEPAL.LENGTH") AS AVG_SLENGTH, AVG ("SEPAL.WIDTH") AS AVG_SWIDTH, AVG ("PETAL.LENGTH") AS AVG_PLENGTH, AVG ("PETAL.WIDTH") AS AVG_PWIDTH FROM IRIS GROUP BY ROLLUP (SPECIES)') > iris.summary SPECIES AVG_SLENGTH AVG_SWIDTH AVG_PLENGTH AVG_PWIDTH 1 setosa 5.006000 3.428000 1.462 0.246000 2 versicolor 5.936000 2.770000 4.260 1.326000 3 virginica 6.588000 2.974000 5.552 2.026000 4 <NA> 5.843333 3.057333 3.758 1.199333 Finally, disconnect from the TimesTen Database. > dbCommit (conn) [1] TRUE > dbDisconnect (conn) [1] TRUE We encourage you download Oracle software for evaluation from the Oracle Technology Network. See these links for our software: Times Ten In-Memory Database,  ROracle.  As always, we welcome comments and questions on the TimesTen and  Oracle R technical forums.

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  • .NET HTML Sanitation for rich HTML Input

    - by Rick Strahl
    Recently I was working on updating a legacy application to MVC 4 that included free form text input. When I set up the new site my initial approach was to not allow any rich HTML input, only simple text formatting that would respect a few simple HTML commands for bold, lists etc. and automatically handles line break processing for new lines and paragraphs. This is typical for what I do with most multi-line text input in my apps and it works very well with very little development effort involved. Then the client sprung another note: Oh by the way we have a bunch of customers (real estate agents) who need to post complete HTML documents. Oh uh! There goes the simple theory. After some discussion and pleading on my part (<snicker>) to try and avoid this type of raw HTML input because of potential XSS issues, the client decided to go ahead and allow raw HTML input anyway. There has been lots of discussions on this subject on StackOverFlow (and here and here) but to after reading through some of the solutions I didn't really find anything that would work even closely for what I needed. Specifically we need to be able to allow just about any HTML markup, with the exception of script code. Remote CSS and Images need to be loaded, links need to work and so. While the 'legit' HTML posted by these agents is basic in nature it does span most of the full gamut of HTML (4). Most of the solutions XSS prevention/sanitizer solutions I found were way to aggressive and rendered the posted output unusable mostly because they tend to strip any externally loaded content. In short I needed a custom solution. I thought the best solution to this would be to use an HTML parser - in this case the Html Agility Pack - and then to run through all the HTML markup provided and remove any of the blacklisted tags and a number of attributes that are prone to JavaScript injection. There's much discussion on whether to use blacklists vs. whitelists in the discussions mentioned above, but I found that whitelists can make sense in simple scenarios where you might allow manual HTML input, but when you need to allow a larger array of HTML functionality a blacklist is probably easier to manage as the vast majority of elements and attributes could be allowed. Also white listing gets a bit more complex with HTML5 and the new proliferation of new HTML tags and most new tags generally don't affect XSS issues directly. Pure whitelisting based on elements and attributes also doesn't capture many edge cases (see some of the XSS cheat sheets listed below) so even with a white list, custom logic is still required to handle many of those edge cases. The Microsoft Web Protection Library (AntiXSS) My first thought was to check out the Microsoft AntiXSS library. Microsoft has an HTML Encoding and Sanitation library in the Microsoft Web Protection Library (formerly AntiXSS Library) on CodePlex, which provides stricter functions for whitelist encoding and sanitation. Initially I thought the Sanitation class and its static members would do the trick for me,but I found that this library is way too restrictive for my needs. Specifically the Sanitation class strips out images and links which rendered the full HTML from our real estate clients completely useless. I didn't spend much time with it, but apparently I'm not alone if feeling this library is not really useful without some way to configure operation. To give you an example of what didn't work for me with the library here's a small and simple HTML fragment that includes script, img and anchor tags. I would expect the script to be stripped and everything else to be left intact. Here's the original HTML:var value = "<b>Here</b> <script>alert('hello')</script> we go. Visit the " + "<a href='http://west-wind.com'>West Wind</a> site. " + "<img src='http://west-wind.com/images/new.gif' /> " ; and the code to sanitize it with the AntiXSS Sanitize class:@Html.Raw(Microsoft.Security.Application.Sanitizer.GetSafeHtmlFragment(value)) This produced a not so useful sanitized string: Here we go. Visit the <a>West Wind</a> site. While it removed the <script> tag (good) it also removed the href from the link and the image tag altogether (bad). In some situations this might be useful, but for most tasks I doubt this is the desired behavior. While links can contain javascript: references and images can 'broadcast' information to a server, without configuration to tell the library what to restrict this becomes useless to me. I couldn't find any way to customize the white list, nor is there code available in this 'open source' library on CodePlex. Using Html Agility Pack for HTML Parsing The WPL library wasn't going to cut it. After doing a bit of research I decided the best approach for a custom solution would be to use an HTML parser and inspect the HTML fragment/document I'm trying to import. I've used the HTML Agility Pack before for a number of apps where I needed an HTML parser without requiring an instance of a full browser like the Internet Explorer Application object which is inadequate in Web apps. In case you haven't checked out the Html Agility Pack before, it's a powerful HTML parser library that you can use from your .NET code. It provides a simple, parsable HTML DOM model to full HTML documents or HTML fragments that let you walk through each of the elements in your document. If you've used the HTML or XML DOM in a browser before you'll feel right at home with the Agility Pack. Blacklist based HTML Parsing to strip XSS Code For my purposes of HTML sanitation, the process involved is to walk the HTML document one element at a time and then check each element and attribute against a blacklist. There's quite a bit of argument of what's better: A whitelist of allowed items or a blacklist of denied items. While whitelists tend to be more secure, they also require a lot more configuration. In the case of HTML5 a whitelist could be very extensive. For what I need, I only want to ensure that no JavaScript is executed, so a blacklist includes the obvious <script> tag plus any tag that allows loading of external content including <iframe>, <object>, <embed> and <link> etc. <form>  is also excluded to avoid posting content to a different location. I also disallow <head> and <meta> tags in particular for my case, since I'm only allowing posting of HTML fragments. There is also some internal logic to exclude some attributes or attributes that include references to JavaScript or CSS expressions. The default tag blacklist reflects my use case, but is customizable and can be added to. Here's my HtmlSanitizer implementation:using System.Collections.Generic; using System.IO; using System.Xml; using HtmlAgilityPack; namespace Westwind.Web.Utilities { public class HtmlSanitizer { public HashSet<string> BlackList = new HashSet<string>() { { "script" }, { "iframe" }, { "form" }, { "object" }, { "embed" }, { "link" }, { "head" }, { "meta" } }; /// <summary> /// Cleans up an HTML string and removes HTML tags in blacklist /// </summary> /// <param name="html"></param> /// <returns></returns> public static string SanitizeHtml(string html, params string[] blackList) { var sanitizer = new HtmlSanitizer(); if (blackList != null && blackList.Length > 0) { sanitizer.BlackList.Clear(); foreach (string item in blackList) sanitizer.BlackList.Add(item); } return sanitizer.Sanitize(html); } /// <summary> /// Cleans up an HTML string by removing elements /// on the blacklist and all elements that start /// with onXXX . /// </summary> /// <param name="html"></param> /// <returns></returns> public string Sanitize(string html) { var doc = new HtmlDocument(); doc.LoadHtml(html); SanitizeHtmlNode(doc.DocumentNode); //return doc.DocumentNode.WriteTo(); string output = null; // Use an XmlTextWriter to create self-closing tags using (StringWriter sw = new StringWriter()) { XmlWriter writer = new XmlTextWriter(sw); doc.DocumentNode.WriteTo(writer); output = sw.ToString(); // strip off XML doc header if (!string.IsNullOrEmpty(output)) { int at = output.IndexOf("?>"); output = output.Substring(at + 2); } writer.Close(); } doc = null; return output; } private void SanitizeHtmlNode(HtmlNode node) { if (node.NodeType == HtmlNodeType.Element) { // check for blacklist items and remove if (BlackList.Contains(node.Name)) { node.Remove(); return; } // remove CSS Expressions and embedded script links if (node.Name == "style") { if (string.IsNullOrEmpty(node.InnerText)) { if (node.InnerHtml.Contains("expression") || node.InnerHtml.Contains("javascript:")) node.ParentNode.RemoveChild(node); } } // remove script attributes if (node.HasAttributes) { for (int i = node.Attributes.Count - 1; i >= 0; i--) { HtmlAttribute currentAttribute = node.Attributes[i]; var attr = currentAttribute.Name.ToLower(); var val = currentAttribute.Value.ToLower(); span style="background: white; color: green">// remove event handlers if (attr.StartsWith("on")) node.Attributes.Remove(currentAttribute); // remove script links else if ( //(attr == "href" || attr== "src" || attr == "dynsrc" || attr == "lowsrc") && val != null && val.Contains("javascript:")) node.Attributes.Remove(currentAttribute); // Remove CSS Expressions else if (attr == "style" && val != null && val.Contains("expression") || val.Contains("javascript:") || val.Contains("vbscript:")) node.Attributes.Remove(currentAttribute); } } } // Look through child nodes recursively if (node.HasChildNodes) { for (int i = node.ChildNodes.Count - 1; i >= 0; i--) { SanitizeHtmlNode(node.ChildNodes[i]); } } } } } Please note: Use this as a starting point only for your own parsing and review the code for your specific use case! If your needs are less lenient than mine were you can you can make this much stricter by not allowing src and href attributes or CSS links if your HTML doesn't allow it. You can also check links for external URLs and disallow those - lots of options.  The code is simple enough to make it easy to extend to fit your use cases more specifically. It's also quite easy to make this code work using a WhiteList approach if you want to go that route. The code above is semi-generic for allowing full featured HTML fragments that only disallow script related content. The Sanitize method walks through each node of the document and then recursively drills into all of its children until the entire document has been traversed. Note that the code here uses an XmlTextWriter to write output - this is done to preserve XHTML style self-closing tags which are otherwise left as non-self-closing tags. The sanitizer code scans for blacklist elements and removes those elements not allowed. Note that the blacklist is configurable either in the instance class as a property or in the static method via the string parameter list. Additionally the code goes through each element's attributes and looks for a host of rules gleaned from some of the XSS cheat sheets listed at the end of the post. Clearly there are a lot more XSS vulnerabilities, but a lot of them apply to ancient browsers (IE6 and versions of Netscape) - many of these glaring holes (like CSS expressions - WTF IE?) have been removed in modern browsers. What a Pain To be honest this is NOT a piece of code that I wanted to write. I think building anything related to XSS is better left to people who have far more knowledge of the topic than I do. Unfortunately, I was unable to find a tool that worked even closely for me, or even provided a working base. For the project I was working on I had no choice and I'm sharing the code here merely as a base line to start with and potentially expand on for specific needs. It's sad that Microsoft Web Protection Library is currently such a train wreck - this is really something that should come from Microsoft as the systems vendor or possibly a third party that provides security tools. Luckily for my application we are dealing with a authenticated and validated users so the user base is fairly well known, and relatively small - this is not a wide open Internet application that's directly public facing. As I mentioned earlier in the post, if I had my way I would simply not allow this type of raw HTML input in the first place, and instead rely on a more controlled HTML input mechanism like MarkDown or even a good HTML Edit control that can provide some limits on what types of input are allowed. Alas in this case I was overridden and we had to go forward and allow *any* raw HTML posted. Sometimes I really feel sad that it's come this far - how many good applications and tools have been thwarted by fear of XSS (or worse) attacks? So many things that could be done *if* we had a more secure browser experience and didn't have to deal with every little script twerp trying to hack into Web pages and obscure browser bugs. So much time wasted building secure apps, so much time wasted by others trying to hack apps… We're a funny species - no other species manages to waste as much time, effort and resources as we humans do :-) Resources Code on GitHub Html Agility Pack XSS Cheat Sheet XSS Prevention Cheat Sheet Microsoft Web Protection Library (AntiXss) StackOverflow Links: http://stackoverflow.com/questions/341872/html-sanitizer-for-net http://blog.stackoverflow.com/2008/06/safe-html-and-xss/ http://code.google.com/p/subsonicforums/source/browse/trunk/SubSonic.Forums.Data/HtmlScrubber.cs?r=61© Rick Strahl, West Wind Technologies, 2005-2012Posted in Security  HTML  ASP.NET  JavaScript   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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  • The Execute SQL Task

    In this article we are going to take you through the Execute SQL Task in SQL Server Integration Services for SQL Server 2005 (although it appies just as well to SQL Server 2008).  We will be covering all the essentials that you will need to know to effectively use this task and make it as flexible as possible. The things we will be looking at are as follows: A tour of the Task. The properties of the Task. After looking at these introductory topics we will then get into some examples. The examples will show different types of usage for the task: Returning a single value from a SQL query with two input parameters. Returning a rowset from a SQL query. Executing a stored procedure and retrieveing a rowset, a return value, an output parameter value and passing in an input parameter. Passing in the SQL Statement from a variable. Passing in the SQL Statement from a file. Tour Of The Task Before we can start to use the Execute SQL Task in our packages we are going to need to locate it in the toolbox. Let's do that now. Whilst in the Control Flow section of the package expand your toolbox and locate the Execute SQL Task. Below is how we found ours. Now drag the task onto the designer. As you can see from the following image we have a validation error appear telling us that no connection manager has been assigned to the task. This can be easily remedied by creating a connection manager. There are certain types of connection manager that are compatable with this task so we cannot just create any connection manager and these are detailed in a few graphics time. Double click on the task itself to take a look at the custom user interface provided to us for this task. The task will open on the general tab as shown below. Take a bit of time to have a look around here as throughout this article we will be revisting this page many times. Whilst on the general tab, drop down the combobox next to the ConnectionType property. In here you will see the types of connection manager which this task will accept. As with SQL Server 2000 DTS, SSIS allows you to output values from this task in a number of formats. Have a look at the combobox next to the Resultset property. The major difference here is the ability to output into XML. If you drop down the combobox next to the SQLSourceType property you will see the ways in which you can pass a SQL Statement into the task itself. We will have examples of each of these later on but certainly when we saw these for the first time we were very excited. Next to the SQLStatement property if you click in the empty box next to it you will see ellipses appear. Click on them and you will see the very basic query editor that becomes available to you. Alternatively after you have specified a connection manager for the task you can click on the Build Query button to bring up a completely different query editor. This is slightly inconsistent. Once you've finished looking around the general tab, move on to the next tab which is the parameter mapping tab. We shall, again, be visiting this tab throughout the article but to give you an initial heads up this is where you define the input, output and return values from your task. Note this is not where you specify the resultset. If however you now move on to the ResultSet tab this is where you define what variable will receive the output from your SQL Statement in whatever form that is. Property Expressions are one of the most amazing things to happen in SSIS and they will not be covered here as they deserve a whole article to themselves. Watch out for this as their usefulness will astound you. For a more detailed discussion of what should be the parameter markers in the SQL Statements on the General tab and how to map them to variables on the Parameter Mapping tab see Working with Parameters and Return Codes in the Execute SQL Task. Task Properties There are two places where you can specify the properties for your task. One is in the task UI itself and the other is in the property pane which will appear if you right click on your task and select Properties from the context menu. We will be doing plenty of property setting in the UI later so let's take a moment to have a look at the property pane. Below is a graphic showing our properties pane. Now we shall take you through all the properties and tell you exactly what they mean. A lot of these properties you will see across all tasks as well as the package because of everything's base structure The Container. BypassPrepare Should the statement be prepared before sending to the connection manager destination (True/False) Connection This is simply the name of the connection manager that the task will use. We can get this from the connection manager tray at the bottom of the package. DelayValidation Really interesting property and it tells the task to not validate until it actually executes. A usage for this may be that you are operating on table yet to be created but at runtime you know the table will be there. Description Very simply the description of your Task. Disable Should the task be enabled or not? You can also set this through a context menu by right clicking on the task itself. DisableEventHandlers As a result of events that happen in the task, should the event handlers for the container fire? ExecValueVariable The variable assigned here will get or set the execution value of the task. Expressions Expressions as we mentioned earlier are a really powerful tool in SSIS and this graphic below shows us a small peek of what you can do. We select a property on the left and assign an expression to the value of that property on the right causing the value to be dynamically changed at runtime. One of the most obvious uses of this is that the property value can be built dynamically from within the package allowing you a great deal of flexibility FailPackageOnFailure If this task fails does the package? FailParentOnFailure If this task fails does the parent container? A task can he hosted inside another container i.e. the For Each Loop Container and this would then be the parent. ForcedExecutionValue This property allows you to hard code an execution value for the task. ForcedExecutionValueType What is the datatype of the ForcedExecutionValue? ForceExecutionResult Force the task to return a certain execution result. This could then be used by the workflow constraints. Possible values are None, Success, Failure and Completion. ForceExecutionValue Should we force the execution result? IsolationLevel This is the transaction isolation level of the task. IsStoredProcedure Certain optimisations are made by the task if it knows that the query is a Stored Procedure invocation. The docs say this will always be false unless the connection is an ADO connection. LocaleID Gets or sets the LocaleID of the container. LoggingMode Should we log for this container and what settings should we use? The value choices are UseParentSetting, Enabled and Disabled. MaximumErrorCount How many times can the task fail before we call it a day? Name Very simply the name of the task. ResultSetType How do you want the results of your query returned? The choices are ResultSetType_None, ResultSetType_SingleRow, ResultSetType_Rowset and ResultSetType_XML. SqlStatementSource Your Query/SQL Statement. SqlStatementSourceType The method of specifying the query. Your choices here are DirectInput, FileConnection and Variables TimeOut How long should the task wait to receive results? TransactionOption How should the task handle being asked to join a transaction? Usage Examples As we move through the examples we will only cover in them what we think you must know and what we think you should see. This means that some of the more elementary steps like setting up variables will be covered in the early examples but skipped and simply referred to in later ones. All these examples used the AventureWorks database that comes with SQL Server 2005. Returning a Single Value, Passing in Two Input Parameters So the first thing we are going to do is add some variables to our package. The graphic below shows us those variables having been defined. Here the CountOfEmployees variable will be used as the output from the query and EndDate and StartDate will be used as input parameters. As you can see all these variables have been scoped to the package. Scoping allows us to have domains for variables. Each container has a scope and remember a package is a container as well. Variable values of the parent container can be seen in child containers but cannot be passed back up to the parent from a child. Our following graphic has had a number of changes made. The first of those changes is that we have created and assigned an OLEDB connection manager to this Task ExecuteSQL Task Connection. The next thing is we have made sure that the SQLSourceType property is set to Direct Input as we will be writing in our statement ourselves. We have also specified that only a single row will be returned from this query. The expressions we typed in was: SELECT COUNT(*) AS CountOfEmployees FROM HumanResources.Employee WHERE (HireDate BETWEEN ? AND ?) Moving on now to the Parameter Mapping tab this is where we are going to tell the task about our input paramaters. We Add them to the window specifying their direction and datatype. A quick word here about the structure of the variable name. As you can see SSIS has preceeded the variable with the word user. This is a default namespace for variables but you can create your own. When defining your variables if you look at the variables window title bar you will see some icons. If you hover over the last one on the right you will see it says "Choose Variable Columns". If you click the button you will see a list of checkbox options and one of them is namespace. after checking this you will see now where you can define your own namespace. The next tab, result set, is where we need to get back the value(s) returned from our statement and assign to a variable which in our case is CountOfEmployees so we can use it later perhaps. Because we are only returning a single value then if you remember from earlier we are allowed to assign a name to the resultset but it must be the name of the column (or alias) from the query. A really cool feature of Business Intelligence Studio being hosted by Visual Studio is that we get breakpoint support for free. In our package we set a Breakpoint so we can break the package and have a look in a watch window at the variable values as they appear to our task and what the variable value of our resultset is after the task has done the assignment. Here's that window now. As you can see the count of employess that matched the data range was 2. Returning a Rowset In this example we are going to return a resultset back to a variable after the task has executed not just a single row single value. There are no input parameters required so the variables window is nice and straight forward. One variable of type object. Here is the statement that will form the soure for our Resultset. select p.ProductNumber, p.name, pc.Name as ProductCategoryNameFROM Production.ProductCategory pcJOIN Production.ProductSubCategory pscON pc.ProductCategoryID = psc.ProductCategoryIDJOIN Production.Product pON psc.ProductSubCategoryID = p.ProductSubCategoryID We need to make sure that we have selected Full result set as the ResultSet as shown below on the task's General tab. Because there are no input parameters we can skip the parameter mapping tab and move straight to the Result Set tab. Here we need to Add our variable defined earlier and map it to the result name of 0 (remember we covered this earlier) Once we run the task we can again set a breakpoint and have a look at the values coming back from the task. In the following graphic you can see the result set returned to us as a COM object. We can do some pretty interesting things with this COM object and in later articles that is exactly what we shall be doing. Return Values, Input/Output Parameters and Returning a Rowset from a Stored Procedure This example is pretty much going to give us a taste of everything. We have already covered in the previous example how to specify the ResultSet to be a Full result set so we will not cover it again here. For this example we are going to need 4 variables. One for the return value, one for the input parameter, one for the output parameter and one for the result set. Here is the statement we want to execute. Note how much cleaner it is than if you wanted to do it using the current version of DTS. In the Parameter Mapping tab we are going to Add our variables and specify their direction and datatypes. In the Result Set tab we can now map our final variable to the rowset returned from the stored procedure. It really is as simple as that and we were amazed at how much easier it is than in DTS 2000. Passing in the SQL Statement from a Variable SSIS as we have mentioned is hugely more flexible than its predecessor and one of the things you will notice when moving around the tasks and the adapters is that a lot of them accept a variable as an input for something they need. The ExecuteSQL task is no different. It will allow us to pass in a string variable as the SQL Statement. This variable value could have been set earlier on from inside the package or it could have been populated from outside using a configuration. The ResultSet property is set to single row and we'll show you why in a second when we look at the variables. Note also the SQLSourceType property. Here's the General Tab again. Looking at the variable we have in this package you can see we have only two. One for the return value from the statement and one which is obviously for the statement itself. Again we need to map the Result name to our variable and this can be a named Result Name (The column name or alias returned by the query) and not 0. The expected result into our variable should be the amount of rows in the Person.Contact table and if we look in the watch window we see that it is.   Passing in the SQL Statement from a File The final example we are going to show is a really interesting one. We are going to pass in the SQL statement to the task by using a file connection manager. The file itself contains the statement to run. The first thing we are going to need to do is create our file connection mananger to point to our file. Click in the connections tray at the bottom of the designer, right click and choose "New File Connection" As you can see in the graphic below we have chosen to use an existing file and have passed in the name as well. Have a look around at the other "Usage Type" values available whilst you are here. Having set that up we can now see in the connection manager tray our file connection manager sitting alongside our OLE-DB connection we have been using for the rest of these examples. Now we can go back to the familiar General Tab to set up how the task will accept our file connection as the source. All the other properties in this task are set up exactly as we have been doing for other examples depending on the options chosen so we will not cover them again here.   We hope you will agree that the Execute SQL Task has changed considerably in this release from its DTS predecessor. It has a lot of options available but once you have configured it a few times you get to learn what needs to go where. We hope you have found this article useful.

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  • Understanding C# async / await (1) Compilation

    - by Dixin
    Now the async / await keywords are in C#. Just like the async and ! in F#, this new C# feature provides great convenience. There are many nice documents talking about how to use async / await in specific scenarios, like using async methods in ASP.NET 4.5 and in ASP.NET MVC 4, etc. In this article we will look at the real code working behind the syntax sugar. According to MSDN: The async modifier indicates that the method, lambda expression, or anonymous method that it modifies is asynchronous. Since lambda expression / anonymous method will be compiled to normal method, we will focus on normal async method. Preparation First of all, Some helper methods need to make up. internal class HelperMethods { internal static int Method(int arg0, int arg1) { // Do some IO. WebClient client = new WebClient(); Enumerable.Repeat("http://weblogs.asp.net/dixin", 10) .Select(client.DownloadString).ToArray(); int result = arg0 + arg1; return result; } internal static Task<int> MethodTask(int arg0, int arg1) { Task<int> task = new Task<int>(() => Method(arg0, arg1)); task.Start(); // Hot task (started task) should always be returned. return task; } internal static void Before() { } internal static void Continuation1(int arg) { } internal static void Continuation2(int arg) { } } Here Method() is a long running method doing some IO. Then MethodTask() wraps it into a Task and return that Task. Nothing special here. Await something in async method Since MethodTask() returns Task, let’s try to await it: internal class AsyncMethods { internal static async Task<int> MethodAsync(int arg0, int arg1) { int result = await HelperMethods.MethodTask(arg0, arg1); return result; } } Because we used await in the method, async must be put on the method. Now we get the first async method. According to the naming convenience, it is called MethodAsync. Of course a async method can be awaited. So we have a CallMethodAsync() to call MethodAsync(): internal class AsyncMethods { internal static async Task<int> CallMethodAsync(int arg0, int arg1) { int result = await MethodAsync(arg0, arg1); return result; } } After compilation, MethodAsync() and CallMethodAsync() becomes the same logic. This is the code of MethodAsyc(): internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MethodAsync(int arg0, int arg1) { MethodAsyncStateMachine methodAsyncStateMachine = new MethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; methodAsyncStateMachine.Builder.Start(ref methodAsyncStateMachine); return methodAsyncStateMachine.Builder.Task; } } It just creates and starts a state machine MethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Result; private TaskAwaiter<int> awaitor; void IAsyncStateMachine.MoveNext() { try { if (this.State != 0) { this.awaitor = HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaitor.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaitor, ref this); return; } } else { this.State = -1; } this.Result = this.awaitor.GetResult(); } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); return; } this.State = -2; this.Builder.SetResult(this.Result); } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine param0) { this.Builder.SetStateMachine(param0); } } The generated code has been cleaned up so it is readable and can be compiled. Several things can be observed here: The async modifier is gone, which shows, unlike other modifiers (e.g. static), there is no such IL/CLR level “async” stuff. It becomes a AsyncStateMachineAttribute. This is similar to the compilation of extension method. The generated state machine is very similar to the state machine of C# yield syntax sugar. The local variables (arg0, arg1, result) are compiled to fields of the state machine. The real code (await HelperMethods.MethodTask(arg0, arg1)) is compiled into MoveNext(): HelperMethods.MethodTask(this.Arg0, this.Arg1).GetAwaiter(). CallMethodAsync() will create and start its own state machine CallMethodAsyncStateMachine: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(CallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> CallMethodAsync(int arg0, int arg1) { CallMethodAsyncStateMachine callMethodAsyncStateMachine = new CallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; callMethodAsyncStateMachine.Builder.Start(ref callMethodAsyncStateMachine); return callMethodAsyncStateMachine.Builder.Task; } } CallMethodAsyncStateMachine has the same logic as MethodAsyncStateMachine above. The detail of the state machine will be discussed soon. Now it is clear that: async /await is a C# level syntax sugar. There is no difference to await a async method or a normal method. A method returning Task will be awaitable. State machine and continuation To demonstrate more details in the state machine, a more complex method is created: internal class AsyncMethods { internal static async Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; } } In this method: There are multiple awaits. There are code before the awaits, and continuation code after each await After compilation, this multi-await method becomes the same as above single-await methods: internal class CompiledAsyncMethods { [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, Builder = AsyncTaskMethodBuilder<int>.Create(), State = -1 }; multiCallMethodAsyncStateMachine.Builder.Start(ref multiCallMethodAsyncStateMachine); return multiCallMethodAsyncStateMachine.Builder.Task; } } It creates and starts one single state machine, MultiCallMethodAsyncStateMachine: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { public int State; public AsyncTaskMethodBuilder<int> Builder; public int Arg0; public int Arg1; public int Arg2; public int Arg3; public int ResultOfAwait1; public int ResultOfAwait2; public int ResultToReturn; private TaskAwaiter<int> awaiter; void IAsyncStateMachine.MoveNext() { try { switch (this.State) { case -1: HelperMethods.Before(); this.awaiter = AsyncMethods.MethodAsync(this.Arg0, this.Arg1).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 0; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 0: this.ResultOfAwait1 = this.awaiter.GetResult(); HelperMethods.Continuation1(this.ResultOfAwait1); this.awaiter = AsyncMethods.MethodAsync(this.Arg2, this.Arg3).GetAwaiter(); if (!this.awaiter.IsCompleted) { this.State = 1; this.Builder.AwaitUnsafeOnCompleted(ref this.awaiter, ref this); } break; case 1: this.ResultOfAwait2 = this.awaiter.GetResult(); HelperMethods.Continuation2(this.ResultOfAwait2); this.ResultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; this.State = -2; this.Builder.SetResult(this.ResultToReturn); break; } } catch (Exception exception) { this.State = -2; this.Builder.SetException(exception); } } [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { this.Builder.SetStateMachine(stateMachine); } } The above code is already cleaned up, but there are still a lot of things. More clean up can be done, and the state machine can be very simple: [CompilerGenerated] [StructLayout(LayoutKind.Auto)] internal struct MultiCallMethodAsyncStateMachine : IAsyncStateMachine { // State: // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End public int State; public TaskCompletionSource<int> ResultToReturn; // int resultToReturn ... public int Arg0; // int Arg0 public int Arg1; // int arg1 public int Arg2; // int arg2 public int Arg3; // int arg3 public int ResultOfAwait1; // int resultOfAwait1 ... public int ResultOfAwait2; // int resultOfAwait2 ... private Task<int> currentTaskToAwait; /// <summary> /// Moves the state machine to its next state. /// </summary> void IAsyncStateMachine.MoveNext() { try { switch (this.State) { // Orginal code is splitted by "case"s: // case -1: // HelperMethods.Before(); // MethodAsync(Arg0, arg1); // case 0: // int resultOfAwait1 = await ... // HelperMethods.Continuation1(resultOfAwait1); // MethodAsync(arg2, arg3); // case 1: // int resultOfAwait2 = await ... // HelperMethods.Continuation2(resultOfAwait2); // int resultToReturn = resultOfAwait1 + resultOfAwait2; // return resultToReturn; case -1: // -1 is begin. HelperMethods.Before(); // Code before 1st await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg0, this.Arg1); // 1st task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 0. this.State = 0; IAsyncStateMachine this1 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this1.MoveNext()); // Callback break; case 0: // Now 1st await is done. this.ResultOfAwait1 = this.currentTaskToAwait.Result; // Get 1st await's result. HelperMethods.Continuation1(this.ResultOfAwait1); // Code after 1st await and before 2nd await. this.currentTaskToAwait = AsyncMethods.MethodAsync(this.Arg2, this.Arg3); // 2nd task to await // When this.currentTaskToAwait is done, run this.MoveNext() and go to case 1. this.State = 1; IAsyncStateMachine this2 = this; // Cannot use "this" in lambda so create a local variable. this.currentTaskToAwait.ContinueWith(_ => this2.MoveNext()); // Callback break; case 1: // Now 2nd await is done. this.ResultOfAwait2 = this.currentTaskToAwait.Result; // Get 2nd await's result. HelperMethods.Continuation2(this.ResultOfAwait2); // Code after 2nd await. int resultToReturn = this.ResultOfAwait1 + this.ResultOfAwait2; // Code after 2nd await. // End with resultToReturn. this.State = -2; // -2 is end. this.ResultToReturn.SetResult(resultToReturn); break; } } catch (Exception exception) { // End with exception. this.State = -2; // -2 is end. this.ResultToReturn.SetException(exception); } } /// <summary> /// Configures the state machine with a heap-allocated replica. /// </summary> /// <param name="stateMachine">The heap-allocated replica.</param> [DebuggerHidden] void IAsyncStateMachine.SetStateMachine(IAsyncStateMachine stateMachine) { // No core logic. } } Only Task and TaskCompletionSource are involved in this version. And MultiCallMethodAsync() can be simplified to: [DebuggerStepThrough] [AsyncStateMachine(typeof(MultiCallMethodAsyncStateMachine))] // async internal static /*async*/ Task<int> MultiCallMethodAsync_(int arg0, int arg1, int arg2, int arg3) { MultiCallMethodAsyncStateMachine multiCallMethodAsyncStateMachine = new MultiCallMethodAsyncStateMachine() { Arg0 = arg0, Arg1 = arg1, Arg2 = arg2, Arg3 = arg3, ResultToReturn = new TaskCompletionSource<int>(), // -1: Begin // 0: 1st await is done // 1: 2nd await is done // ... // -2: End State = -1 }; (multiCallMethodAsyncStateMachine as IAsyncStateMachine).MoveNext(); // Original code are in this method. return multiCallMethodAsyncStateMachine.ResultToReturn.Task; } Now the whole state machine becomes very clear - it is about callback: Original code are split into pieces by “await”s, and each piece is put into each “case” in the state machine. Here the 2 awaits split the code into 3 pieces, so there are 3 “case”s. The “piece”s are chained by callback, that is done by Builder.AwaitUnsafeOnCompleted(callback), or currentTaskToAwait.ContinueWith(callback) in the simplified code. A previous “piece” will end with a Task (which is to be awaited), when the task is done, it will callback the next “piece”. The state machine’s state works with the “case”s to ensure the code “piece”s executes one after another. Callback Since it is about callback, the simplification  can go even further – the entire state machine can be completely purged. Now MultiCallMethodAsync() becomes: internal static Task<int> MultiCallMethodAsync(int arg0, int arg1, int arg2, int arg3) { TaskCompletionSource<int> taskCompletionSource = new TaskCompletionSource<int>(); try { // Oringinal code begins. HelperMethods.Before(); MethodAsync(arg0, arg1).ContinueWith(await1 => { int resultOfAwait1 = await1.Result; HelperMethods.Continuation1(resultOfAwait1); MethodAsync(arg2, arg3).ContinueWith(await2 => { int resultOfAwait2 = await2.Result; HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; // Oringinal code ends. taskCompletionSource.SetResult(resultToReturn); }); }); } catch (Exception exception) { taskCompletionSource.SetException(exception); } return taskCompletionSource.Task; } Please compare with the original async / await code: HelperMethods.Before(); int resultOfAwait1 = await MethodAsync(arg0, arg1); HelperMethods.Continuation1(resultOfAwait1); int resultOfAwait2 = await MethodAsync(arg2, arg3); HelperMethods.Continuation2(resultOfAwait2); int resultToReturn = resultOfAwait1 + resultOfAwait2; return resultToReturn; Yeah that is the magic of C# async / await: Await is literally pretending to wait. In a await expression, a Task object will be return immediately so that caller is not blocked. The continuation code is compiled as that Task’s callback code. When that task is done, continuation code will execute. Please notice that many details inside the state machine are omitted for simplicity, like context caring, etc. If you want to have a detailed picture, please do check out the source code of AsyncTaskMethodBuilder and TaskAwaiter.

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  • Understanding RTF and edit it with vb.net

    - by Jacob Kofoed
    I have this RichTextbox in my vb.net form and I would like to when a user click a button, for example to embold the selected text, how would I do this. Also, I do NOT want to use the standard vb.net expressions such as RichTextBox1.SelectedText.Font.Bold = true. I want to do something like RichTextbox1.SelectedRTF="[bold]" & RichTextBox1.SelectedRTF & "[/bold]" or whatever RTF looks like. Can I just add the RTF options random places or can a RichTextBox return an error if the text is in wrong format. I'm mostly looking for info on how to work with RTF without using the standard vb expressions. Thank you very much for any help provided

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  • How to use SQL Expression Fields of Crystal Report 11.5 from VB.NET 2008

    - by Tareq
    I have the following SQL Expression Field in my Crystal Report 11.5 {fn CONCAT({fn CONCAT("SPR_PRODUCT"."PRODUCT_ID","SPR_PRODUCT_SUB_ITEM"."P_SUB_ITEM_ID" )},{fn CONCAT("SPR_PRODUCT_ITEM"."P_ITEM_ID","SPR_PRODUCT_GROUP"."P_GROUP_ID" )} )} It works well in the Preview Mode. But when I use the report in my VB.NET 2008 Project it says the following: Error in compiling SQL Expression : SQL Expressions can not be used in this report.. Error in File <...>.rpt: SQL Expression error: Error in compiling SQL Expression : SQL Expressions can not be used in this report... Please help me by telling how can I use the SQL Expression field in VB.NET ? Thanks in Advance.

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  • How can I extend DynamicQuery.cs to implement a .Single method?

    - by Yoenhofen
    I need to write some dynamic queries for a project I'm working on. I'm finding out that a significant amount of time is being spent by my program on the Count and First methods, so I started to change to .Single, only to find out that there is no such method. The code below was my first attempt at creating one (mostly copied from the Where method), but it's not working. Help? public static object Single(this IQueryable source, string predicate, params object[] values) { if (source == null) throw new ArgumentNullException("source"); if (predicate == null) throw new ArgumentNullException("predicate"); LambdaExpression lambda = DynamicExpression.ParseLambda(source.ElementType, typeof(bool), predicate, values); return source.Provider.CreateQuery( Expression.Call( typeof(Queryable), "Single", new Type[] { source.ElementType }, source.Expression, Expression.Quote(lambda))); }

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  • Cross-table linq query with EF4/POCO

    - by Basiclife
    Hi All, I'm new to EF(any version) and POCO. I'm trying to use POCO entities with a generic repository in a "code-first" mode(?) I've got some POCO Entities (no proxies, no lazy loading, nothing). I have a repository(of T as Entity) which provides me with basic get/getsingle/getfirst functionality which takes a lambda as a parameter (specifically a System.Func(Of T, Boolean)) Now as I'm returning the simplest possible POCO object, none of the relationship parameters work once they've been retrieved from the database (as I would expect). However, I had assumed (wrongly) that my lambda query passed to the repository would be able to use the links between entities as it would be executed against the DB before the simple POCO entities are generated. The flow is: GUI calls: Public Function GetAllTypesForCategory(ByVal CategoryID As Guid) As IEnumerable(Of ItemType) Return ItemTypeRepository.Get(Function(x) x.Category.ID = CategoryID) End Function Get is defined in Repository(of T as Entity): Public Function [Get](ByVal Query As System.Func(Of T, Boolean)) As IEnumerable(Of T) Implements Interfaces.IRepository(Of T).Get Return ObjectSet.Where(Query).ToList() End Function The code doesn't error when this method is called but does when I try to use the result set. (This seems to be a lazy loading behaviour so I tried adding the .ToList() to force eager loading - no difference) I'm using unity/IOC to wire it all up but I believe that's irrelevant to the issue I'm having NB: Relationships between entities are being configured properly and if I turn on proxies/lazy loading/etc... this all just works. I'm intentionally leaving all that turned off as some calls to the BL will be from a website but some will be via WCF - So I want the simplest possible objects. Also, I don't want a change in an object passed to the UI to be committed to the DB if another BL method calls Commit() Can someone please either point out how to make this work or explain why it's not possible? All I want to do is make sure the lambda I pass in is performed against the DB before the results are returned Many thanks. In case it matters, the container is being populated with everything as shown below: Container.AddNewExtension(Of EFRepositoryExtension)() Container.Configure(Of IEFRepositoryExtension)(). WithConnection(ConnectionString). WithContextLifetime(New HttpContextLifetimeManager(Of IObjectContext)()). ConfigureEntity(New CategoryConfig(), "Categories"). ConfigureEntity(New ItemConfig()). ... )

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  • Django doesn't refresh my request object when reloading the current page.

    - by Boris Rusev
    I have a Django web site which I want ot be viewable in different languages. Until this morning everything was working fine. Here is the deal. I go to my say About Us page and it is in English. Below it there is the change language button and when I press it everything "magically" translates to Bulgarian just the way I want it. On the other hand I have a JS menu from which the user is able to browse through the products. I click on 'T-Shirt' then a sub-menu opens bellow the previously pressed containing different categories - Men, Women, Children. The link guides me to a page where the exact clothes I have requested are listed. BUT... When I try to change the language THEN, nothing happens. I go to the Abouts Page, change the language from there, return to the clothes catalog and the language is changed... I will no paste some code. This is my change button code: function changeLanguage() { if (getCookie('language') == 'EN') { setCookie("language", 'BG'); } else { setCookie("language", 'EN'); } window.location.reload(); } These are my URL patterns: urlpatterns = patterns('', # Example: # (r'^enter_clothing/', include('enter_clothing.foo.urls')), # Uncomment the admin/doc line below and add 'django.contrib.admindocs' # to INSTALLED_APPS to enable admin documentation: # (r'^admin/doc/', include('django.contrib.admindocs.urls')), # Uncomment the next line to enable the admin: (r'^site_media/(?P<path>.*)$', 'django.views.static.serve', {'document_root': '/home/boris/Projects/enter_clothing/templates/media', 'show_indexes': True}), (r'^$', 'enter_clothing.clothes_app.views.index'), (r'^home', 'enter_clothing.clothes_app.views.home'), (r'^products', 'enter_clothing.clothes_app.views.products'), (r'^orders', 'enter_clothing.clothes_app.views.orders'), (r'^aboutUs', 'enter_clothing.clothes_app.views.aboutUs'), (r'^contactUs', 'enter_clothing.clothes_app.views.contactUs'), (r'^admin/', include(admin.site.urls)), (r'^(\w+)/(\w+)/page=(\d+)', 'enter_clothing.clothes_app.views.displayClothes'), ) My About Us page: @base def aboutUs(request): return """<b>%s</b>""" % getTranslation("About Us Text", request.COOKIES['language']) The @base method: def base(myfunc): def inner_func(*args, **kwargs): try: args[0].COOKIES['language'] except: args[0].COOKIES['language'] = 'BG' resetGlobalVariables() initCollections(args[0]) categoriesByCollection = dict((collection, getCategoriesFromCollection(args[0], collection)) for collection in collections) if args[0].COOKIES['language'] == 'BG': for k, v in categoriesByCollection.iteritems(): categoriesByCollection[k] = reduce(lambda a,b: a+b, map(lambda x: """<li><a href="/%s/%s/page=1">%s</a></li>""" % (translateCategory(args[0], x), translateCollection(args[0], k), str(x)), v), "") else: for k, v in categoriesByCollection.iteritems(): categoriesByCollection[k] = reduce(lambda a,b: a+b, map(lambda x: """<li><a href="/%s/%s/page=1">%s</a></li>""" % (str(x), str(k), str(x)), v), "") contents = myfunc(*args, **kwargs) return render_to_response('index.html', {'title': title, 'categoriesByCollection': categoriesByCollection.iteritems(), 'keys': enumerate(keys), 'values': enumerate(values), 'contents': contents, 'btnHome':getTranslation("Home Button", args[0].COOKIES['language']), 'btnProducts':getTranslation("Products Button", args[0].COOKIES['language']), 'btnOrders':getTranslation("Orders Button", args[0].COOKIES['language']), 'btnAboutUs':getTranslation("About Us Button", args[0].COOKIES['language']), 'btnContacts':getTranslation("Contact Us Button", args[0].COOKIES['language']), 'btnChangeLanguage':getTranslation("Button Change Language", args[0].COOKIES['language'])}) return inner_func And the catalog page: @base def displayClothes(request, category, collection, page): clothesToDisplay = getClothesFromCollectionAndCategory(request, category, collection) contents = "" pageCount = len(clothesToDisplay) / ( rowCount * columnCount) + 1 matrixSize = rowCount * columnCount currentPage = str(page).replace("page=", "") currentPage = int(currentPage) - 1 #raise Exception(request) # this is for the clothes layout for x in range(currentPage * matrixSize, matrixSize * (currentPage + 1)): if x < len(clothesToDisplay): if request.COOKIES['language'] == 'EN': contents += """<div class="clothes">%s</div>""" % clothesToDisplay[x].getEnglishHTML() else: contents += """<div class="clothes">%s</div>""" % clothesToDisplay[x].getBulgarianHTML() if (x + 1) % columnCount == 0: contents += """<div class="clear"></div>""" contents += """<div class="clear"></div>""" # this is for the page links if pageCount > 1: for x in range(0, pageCount): if x == currentPage: contents += """<a href="/%s/%s/page=%s"><span style="font-size: 20pt; color: black;">%s</span></a>""" % (category, collection, x + 1, x + 1) else: contents += """<a href="/%s/%s/page=%s"><span style="font-size: 20pt; color: blue;">%s</span></a>""" % (category, collection, x + 1, x + 1) return """%s""" % (contents) Let me explain that you needn't be alarmed by the large quantities of code I have posted. You don't have to understand it or even look at all of it. I've published it just in case because I really can't understand the origins of the bug. Now this is how I have narrowed the problem. I am debuging with "raise Exception(request)" every time I want to know what's inside my request object. When I place this in my aboutUs method, the language cookie value changes every time I press the language button. But NOT when I am in the displayClothes method. There the language stays the same. Also I tried putting the exception line in the beginning of the @base method. It turns out the situation there is exactly the same. When I am in my About Us page and click on the button, the language in my request object changes, but when I press the button while in the catalog page it remains unchanged. That is all I could find, and I have no idea as to how Django distinguishes my pages and in what way. P.S. The JavaScript I think works perfectly, I have tested it in multiple ways. Thank you, I hope some of you will read this enormous post, and don't hesitate to ask for more code excerpts.

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  • Handle "Cannot access a closed resource set"

    - by Philip
    I have a website with several languages in a database. From the database I use ResXResourceWriter to create my .resx files. This is working really good but sometimes I get this exception: MESSAGE: Cannot access a closed resource set. SOURCE: mscorlib FORM: QUERYSTRING: TARGETSITE: System.Object GetObject(System.String, Boolean, Boolean) STACKTRACE: at System.Resources.RuntimeResourceSet.GetObject(String key, Boolean ignoreCase, Boolean isString) at System.Resources.RuntimeResourceSet.GetString(String key, Boolean ignoreCase) at System.Resources.ResourceManager.GetString(String name, CultureInfo culture) at System.Linq.Expressions.Expression.ValidateStaticOrInstanceMethod(Expression instance, MethodInfo method) at System.Linq.Expressions.Expression.Call(Expression instance, MethodInfo method, IEnumerable`1 arguments) at System.Data.Linq.DataContext.GetMethodCall(Object instance, MethodInfo methodInfo, Object[] parameters) at System.Data.Linq.DataContext.ExecuteMethodCall(Object instance, MethodInfo methodInfo, Object[] parameters) at Business.DatabaseModelDataContext.Web_GetMostPlayedEvents(String cultureCode) at Presentation.Default.Page_Load(Object sender, EventArgs e) at System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) I don't know why this is happening or how to solve it. Does anyone know anything about this? Thanks, Philip

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  • About "If.." in Scheme (plt-scheme)

    - by Amit
    I had a pretty simple requirement in my Scheme program to execute more than one statement, in the true condition of a 'if'. . So I write my code, something like this: (if (= 1 1) ((expression1) (expression2)) ; these 2 expressions are to be executed when the condition is true (expression3) ) Obviously, the above doesn't work, since I have unintentionally created a # procedure with # arguments. So, to get my work done, I simply put the above expressions in a new function and call it from there, in place of the expression1, expression2. It works. So, my point here is: is there any other conditional construct which may support my requirement here?

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