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• A star algorithm implementation problems

  - by bryan226

  I’m having some trouble implementing the A* algorithm in a 2D tile based game. The problem is basically that the algorithm gets stuck when something gets in its direct way (e.g. walls) Note that it only allows Horizontal and Vertical movement. Here's a picture as it works fine across the map without something in its direct way: (Green tile = destination, Blue = In closed list, Green = in open list) This is what happens if I try to walk 'around' a wall: I calculate costs with the F = G + H formula: G = 1 Cost per Step H = 10 Cost per Step //Count how many tiles are between current-tile & destination-tile The functions: short c_astar::GuessH(short Startx,short Starty,short Destinationx,short Destinationy) { hgeVector Start, Destination; Start.x = Startx; Start.y = Starty; Destination.x = Destinationx; Destination.y = Destinationy; short a = 0; short b = 0; if(Start.x > Destination.x) a = Start.x - Destination.x; else a = Destination.x - Start.x; if(Start.y > Destination.y) b = Start.y - Destination.y; else b = Destination.y - Start.y; return (a+b)*10; } short c_astar::GuessG(short Startx,short Starty,short Currentx,short Currenty) { hgeVector Start, Destination; Start.x = Startx; Start.y = Starty; Destination.x = Currentx; Destination.y = Currenty; short a = 0; short b = 0; if(Start.x > Destination.x) a = Start.x - Destination.x; else a = Destination.x - Start.x; if(Start.y > Destination.y) b = Start.y - Destination.y; else b = Destination.y - Start.y; return (a+b); } At the end of the loop I check which tile is the cheapest to go according to its F value: Then some quick checks are done for each tile (UP,DOWN,LEFT,RIGHT): //...CX are holding the F value of the TILE specified // Info: C0 = Center (Current) // C1 = UP // C2 = DOWN // C3 = LEFT // C4 = RIGHT //Quick checks if(((C1 < C2) && (C1 < C3) && (C1 < C4))) { Current.y -= 1; bSimilar = false; if(DEBUG) hge->System_Log("C1 < ALL"); } //.. same for C2,C3 & C4 If there are multiple tiles with the same F value: It’s actually a switch for DOWNLEFT,UPRIGHT.. etc. Here’s one of it: case UPRIGHT: { //UP Temporary = Current; Temporary.y -= 1; bTileStatus[0] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[0]) { //Proceed normal we are OK & walkable Tilex.Tile = map.at(Temporary.y).at(Temporary.x); //Search in lists if(SearchInClosedList(Tilex.Tile.ID,C0)) bFoundInClosedList[0] = true; if(SearchInOpenList(Tilex.Tile.ID,C0)) bFoundInOpenList[0] = true; //RIGHT Temporary = Current; Temporary.x += 1; bTileStatus[1] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[1]) { //Proceed normal we are OK & walkable Tilex.Tile = map.at(Temporary.y).at(Temporary.x); //Search in lists if(SearchInClosedList(Tilex.Tile.ID,C0)) bFoundInClosedList[1] = true; if(SearchInOpenList(Tilex.Tile.ID,C0)) bFoundInOpenList[1] = true; //************************************************* // Purpose: ClosedList behavior //************************************************* if(bFoundInClosedList[0] && !bFoundInClosedList[1]) { //UP found in ClosedList. Go RIGHT return RIGHT; } if(!bFoundInClosedList[0] && bFoundInClosedList[1]) { //RIGHT found in ClosedList. Go UP return UP; } if(bFoundInClosedList[0] && bFoundInClosedList[1]) { //Both found in ClosedList. Random value switch(hge->Random_Int(8,9)) { case 8: return UP; break; case 9: return RIGHT; break; } } //************************************************* // Purpose: OpenList behavior //************************************************* if(bFoundInOpenList[0] && !bFoundInOpenList[1]) { //UP found in OpenList. Go RIGHT return RIGHT; } if(!bFoundInOpenList[0] && bFoundInOpenList[1]) { //RIGHT found in OpenList. Go UP return UP; } if(bFoundInOpenList[0] && bFoundInOpenList[1]) { //Both found in OpenList. Random value switch(hge->Random_Int(8,9)) { case 8: return UP; break; case 9: return RIGHT; break; } } } else if(!bTileStatus[1]) { //RIGHT is not walkable OR out of range //Choose UP return UP; } } else if(!bTileStatus[0]) { //UP is not walkable OR out of range //Fast check RIGHT Temporary = Current; Temporary.x += 1; bTileStatus[1] = IsTileWalkable(Temporary.x,Temporary.y); if(bTileStatus[1]) { return RIGHT; } else return FAILED; //Failed, no valid path found! } } break; A log for the second picture: (Cut down to ten passes, because it’s just repeating itself) ----------------------------------------------------- PASS: 1 | C1: 211 | C2: 191 | C3: 211 | C4: 191 DOWN + RIGHT SIMILAR Going DOWN ----------------------------------------------------- PASS: 2 | C1: 200 | C2: 182 | C3: 202 | C4: 182 DOWN + RIGHT SIMILAR Going DOWN ----------------------------------------------------- PASS: 3 | C1: 191 | C2: 193 | C3: 193 | C4: 173 C4 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 4 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going UP Tile(12.000000,5.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 5 | C1: 191 | C2: 173 | C3: 191 | C4: 999 C2 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 6 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going UP Tile(12.000000,5.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 7 | C1: 191 | C2: 173 | C3: 191 | C4: 999 C2 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 8 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going LEFT ----------------------------------------------------- PASS: 9 | C1: 191 | C2: 193 | C3: 193 | C4: 173 C4 < ALL Tile(12.000000,6.000000) not walkable. MAX_F_VALUE set. ----------------------------------------------------- PASS: 10 | C1: 182 | C2: 184 | C3: 182 | C4: 999 UP + LEFT SIMILAR Going LEFT ----------------------------------------------------- Its always going after the cheapest F value, which seems to be wrong. If someone could point me to the right direction I'd be thankful. Regards, bryan226

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• Open GL stars are not rendering

  - by Darestium

  I doing Nehe's Open GL Lesson 9. I'm using SFML for windowing, the strange thing is no stars are rendering. #include <SFML/System.hpp> #include <SFML/Window.hpp> #include <SFML/Graphics.hpp> #include <iostream> void processEvents(sf::Window *app); void processInput(sf::Window *app); void renderGlScene(sf::Window *app); void init(); int loadResources(); const int NUM_OF_STARS = 50; float triRot = 0.0f; float quadRot = 0.0f; bool twinkle = false; bool tKey = false; float zoom = 15.0f; float tilt = 90.0f; float spin = 0.0f; unsigned int loop; unsigned int texture_handle[1]; typedef struct { int r, g, b; float distance; float angle; } stars; stars star[NUM_OF_STARS]; int main() { sf::Window app(sf::VideoMode(800, 600, 32), "Nehe Lesson 9"); app.UseVerticalSync(false); init(); if (loadResources() == -1) { return EXIT_FAILURE; } while (app.IsOpened()) { processEvents(&app); processInput(&app); renderGlScene(&app); app.Display(); } return EXIT_SUCCESS; } int loadResources() { sf::Image img_data; // Load Texture if (!img_data.LoadFromFile("data/images/star.bmp")) { std::cout << "Could not load data/images/star.bmp"; return -1; } // Generate 1 texture glGenTextures(1, &texture_handle[0]); // Linear filtering glBindTexture(GL_TEXTURE_2D, texture_handle[0]); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, img_data.GetWidth(), img_data.GetHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, img_data.GetPixelsPtr()); return 0; } void processInput(sf::Window *app) { const sf::Input& input = app->GetInput(); if (input.IsKeyDown(sf::Key::T) && !tKey) { tKey = true; twinkle = !twinkle; } if (!input.IsKeyDown(sf::Key::T)) { tKey = false; } if (input.IsKeyDown(sf::Key::Up)) { tilt -= 0.05f; } if (input.IsKeyDown(sf::Key::Down)) { tilt += 0.05f; } if (input.IsKeyDown(sf::Key::PageUp)) { zoom -= 0.02f; } if (input.IsKeyDown(sf::Key::Up)) { zoom += 0.02f; } } void init() { glClearDepth(1.f); glClearColor(0.f, 0.f, 0.f, 0.f); // Enable texturing glEnable(GL_TEXTURE_2D); //glDepthMask(GL_TRUE); // Setup a perpective projection glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.f, 1.f, 1.f, 500.f); glShadeModel(GL_SMOOTH); glBlendFunc(GL_SRC_ALPHA, GL_ONE); glEnable(GL_BLEND); for (loop = 0; loop < NUM_OF_STARS; loop++) { star[loop].distance = (float)loop / NUM_OF_STARS * 5.0f; // Calculate distance from the centre // Give stars random rgb value star[loop].r = rand() % 256; star[loop].g = rand() % 256; star[loop].b = rand() % 256; } } void processEvents(sf::Window *app) { sf::Event event; while (app->GetEvent(event)) { if (event.Type == sf::Event::Closed) { app->Close(); } if (event.Type == sf::Event::KeyPressed && event.Key.Code == sf::Key::Escape) { app->Close(); } } } void renderGlScene(sf::Window *app) { app->SetActive(); // Clear color depth buffer glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); // Apply some transformations glMatrixMode(GL_MODELVIEW); glLoadIdentity(); // Select texture glBindTexture(GL_TEXTURE_2D, texture_handle[0]); for (loop = 0; loop < NUM_OF_STARS; loop++) { glLoadIdentity(); // Reset The View Before We Draw Each Star glTranslatef(0.0f, 0.0f, zoom); // Zoom Into The Screen (Using The Value In 'zoom') glRotatef(tilt, 1.0f, 0.0f, 0.0f); // Tilt The View (Using The Value In 'tilt') glRotatef(star[loop].angle, 0.0f, 1.0f, 0.0f); // Rotate To The Current Stars Angle glTranslatef(star[loop].distance, 0.0f, 0.0f); // Move Forward On The X Plane glRotatef(-star[loop].angle,0.0f,1.0f,0.0f); // Cancel The Current Stars Angle glRotatef(-tilt,1.0f,0.0f,0.0f); // Cancel The Screen Tilt if (twinkle) { glColor4ub(star[(NUM_OF_STARS - loop) - 1].r, star[(NUM_OF_STARS - loop)-1].g, star[(NUM_OF_STARS - loop) - 1].b, 255); glBegin(GL_QUADS); // Begin Drawing The Textured Quad glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f, -1.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f, -1.0f, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f); glEnd(); // Done Drawing The Textured Quad } glRotatef(spin,0.0f,0.0f,1.0f); // Rotate The Star On The Z Axis // Assign A Color Using Bytes glColor4ub(star[loop].r, star[loop].g, star[loop].b, 255); glBegin(GL_QUADS); // Begin Drawing The Textured Quad glTexCoord2f(0.0f, 0.0f); glVertex3f(-1.0f,-1.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 1.0f, 1.0f, 0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-1.0f, 1.0f, 0.0f); glEnd(); // Done Drawing The Textured Quad spin += 0.01f; // Used To Spin The Stars star[loop].angle += (float)loop / NUM_OF_STARS; // Changes The Angle Of A Star star[loop].distance -= 0.01f; // Changes The Distance Of A Star if (star[loop].distance < 0.0f) { star[loop].distance += 5.0f; // Move The Star 5 Units From The Center star[loop].r = rand() % 256; // Give It A New Red Value star[loop].g = rand() % 256; // Give It A New Green Value star[loop].b = rand() % 256; // Give It A New Blue Value } } } I've looked over the code atleast 10 times now and I can't figure out the problem. Any help would be much appreciated.

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• SQL Server Cast

  - by Derek Dieter

  The SQL Server cast function is the easiest data type conversion function to be used compared to the CONVERT function. It takes only one parameter followed by the AS clause to convert a specified value. A quick example is the following:SELECT UserID_String = CAST(UserID AS varchar(50)) FROM dbo.UserThis example will convert the integer to a character value. [...]

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• Uploaded Four New ADF Examples

  - by Steve Muench

  I've uploaded four new examples for your learning pleasure:  162. Set Binding to Attr Value from Selected SelectBooleanRadio Button in Data-Driven Button Group 163. Binding SelectBooleanRadio to True/False Value in DB Row 164. Method Action Invoking Managed Bean Method Without Making Bean a DataControl 165. Using a Headless Taskflow to Perform Work in an Autononmous Transaction Enjoy.

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• PostSharp, Obfuscation, and IL

  - by Simon Cooper

  Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day!

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• Fun with Aggregates

  - by Paul White

  There are interesting things to be learned from even the simplest queries.  For example, imagine you are given the task of writing a query to list AdventureWorks product names where the product has at least one entry in the transaction history table, but fewer than ten. One possible query to meet that specification is: SELECT p.Name FROM Production.Product AS p JOIN Production.TransactionHistory AS th ON p.ProductID = th.ProductID GROUP BY p.ProductID, p.Name HAVING COUNT_BIG(*) < 10; That query correctly returns 23 rows (execution plan and data sample shown below): The execution plan looks a bit different from the written form of the query: the base tables are accessed in reverse order, and the aggregation is performed before the join.  The general idea is to read all rows from the history table, compute the count of rows grouped by ProductID, merge join the results to the Product table on ProductID, and finally filter to only return rows where the count is less than ten. This ‘fully-optimized’ plan has an estimated cost of around 0.33 units.  The reason for the quote marks there is that this plan is not quite as optimal as it could be – surely it would make sense to push the Filter down past the join too?  To answer that, let’s look at some other ways to formulate this query.  This being SQL, there are any number of ways to write logically-equivalent query specifications, so we’ll just look at a couple of interesting ones.  The first query is an attempt to reverse-engineer T-SQL from the optimized query plan shown above.  It joins the result of pre-aggregating the history table to the Product table before filtering: SELECT p.Name FROM ( SELECT th.ProductID, cnt = COUNT_BIG(*) FROM Production.TransactionHistory AS th GROUP BY th.ProductID ) AS q1 JOIN Production.Product AS p ON p.ProductID = q1.ProductID WHERE q1.cnt < 10; Perhaps a little surprisingly, we get a slightly different execution plan: The results are the same (23 rows) but this time the Filter is pushed below the join!  The optimizer chooses nested loops for the join, because the cardinality estimate for rows passing the Filter is a bit low (estimate 1 versus 23 actual), though you can force a merge join with a hint and the Filter still appears below the join.  In yet another variation, the < 10 predicate can be ‘manually pushed’ by specifying it in a HAVING clause in the “q1” sub-query instead of in the WHERE clause as written above. The reason this predicate can be pushed past the join in this query form, but not in the original formulation is simply an optimizer limitation – it does make efforts (primarily during the simplification phase) to encourage logically-equivalent query specifications to produce the same execution plan, but the implementation is not completely comprehensive. Moving on to a second example, the following query specification results from phrasing the requirement as “list the products where there exists fewer than ten correlated rows in the history table”: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) < 10 ); Unfortunately, this query produces an incorrect result (86 rows): The problem is that it lists products with no history rows, though the reasons are interesting.  The COUNT_BIG(*) in the EXISTS clause is a scalar aggregate (meaning there is no GROUP BY clause) and scalar aggregates always produce a value, even when the input is an empty set.  In the case of the COUNT aggregate, the result of aggregating the empty set is zero (the other standard aggregates produce a NULL).  To make the point really clear, let’s look at product 709, which happens to be one for which no history rows exist: -- Scalar aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709;   -- Vector aggregate SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = 709 GROUP BY th.ProductID; The estimated execution plans for these two statements are almost identical: You might expect the Stream Aggregate to have a Group By for the second statement, but this is not the case.  The query includes an equality comparison to a constant value (709), so all qualified rows are guaranteed to have the same value for ProductID and the Group By is optimized away. In fact there are some minor differences between the two plans (the first is auto-parameterized and qualifies for trivial plan, whereas the second is not auto-parameterized and requires cost-based optimization), but there is nothing to indicate that one is a scalar aggregate and the other is a vector aggregate.  This is something I would like to see exposed in show plan so I suggested it on Connect.  Anyway, the results of running the two queries show the difference at runtime: The scalar aggregate (no GROUP BY) returns a result of zero, whereas the vector aggregate (with a GROUP BY clause) returns nothing at all.  Returning to our EXISTS query, we could ‘fix’ it by changing the HAVING clause to reject rows where the scalar aggregate returns zero: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID HAVING COUNT_BIG(*) BETWEEN 1 AND 9 ); The query now returns the correct 23 rows: Unfortunately, the execution plan is less efficient now – it has an estimated cost of 0.78 compared to 0.33 for the earlier plans.  Let’s try adding a redundant GROUP BY instead of changing the HAVING clause: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY th.ProductID HAVING COUNT_BIG(*) < 10 ); Not only do we now get correct results (23 rows), this is the execution plan: I like to compare that plan to quantum physics: if you don’t find it shocking, you haven’t understood it properly :)  The simple addition of a redundant GROUP BY has resulted in the EXISTS form of the query being transformed into exactly the same optimal plan we found earlier.  What’s more, in SQL Server 2008 and later, we can replace the odd-looking GROUP BY with an explicit GROUP BY on the empty set: SELECT p.Name FROM Production.Product AS p WHERE EXISTS ( SELECT * FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ); I offer that as an alternative because some people find it more intuitive (and it perhaps has more geek value too).  Whichever way you prefer, it’s rather satisfying to note that the result of the sub-query does not exist for a particular correlated value where a vector aggregate is used (the scalar COUNT aggregate always returns a value, even if zero, so it always ‘EXISTS’ regardless which ProductID is logically being evaluated). The following query forms also produce the optimal plan and correct results, so long as a vector aggregate is used (you can probably find more equivalent query forms): WHERE Clause SELECT p.Name FROM Production.Product AS p WHERE ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) < 10; APPLY SELECT p.Name FROM Production.Product AS p CROSS APPLY ( SELECT NULL FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () HAVING COUNT_BIG(*) < 10 ) AS ca (dummy); FROM Clause SELECT q1.Name FROM ( SELECT p.Name, cnt = ( SELECT COUNT_BIG(*) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID GROUP BY () ) FROM Production.Product AS p ) AS q1 WHERE q1.cnt < 10; This last example uses SUM(1) instead of COUNT and does not require a vector aggregate…you should be able to work out why :) SELECT q.Name FROM ( SELECT p.Name, cnt = ( SELECT SUM(1) FROM Production.TransactionHistory AS th WHERE th.ProductID = p.ProductID ) FROM Production.Product AS p ) AS q WHERE q.cnt < 10; The semantics of SQL aggregates are rather odd in places.  It definitely pays to get to know the rules, and to be careful to check whether your queries are using scalar or vector aggregates.  As we have seen, query plans do not show in which ‘mode’ an aggregate is running and getting it wrong can cause poor performance, wrong results, or both. © 2012 Paul White Twitter: @SQL_Kiwi email: [email protected]

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• SQL SERVER – Weekly Series – Memory Lane – #031

  - by Pinal Dave

  Here is the list of selected articles of SQLAuthority.com across all these years. Instead of just listing all the articles I have selected a few of my most favorite articles and have listed them here with additional notes below it. Let me know which one of the following is your favorite article from memory lane. 2007 Find Table without Clustered Index – Find Table with no Primary Key Clustered index is very important concept for any table. They impact the performance very heavily. Here is a quick script to find tables without a clustered index. Replace TEXT with VARCHAR(MAX) – Stop using TEXT, NTEXT, IMAGE Data Types Question: “Is VARCHAR (MAX) big enough to store the TEXT field?” Answer: “Yes, VARCHAR(MAX) is big enough to accommodate TEXT field. TEXT, NTEXT and IMAGE data types of SQL Server 2000 will be deprecated in a future version of SQL Server, SQL Server 2005 provides backward compatibility to data types but it is recommended to use new data types which are VARHCAR (MAX), NVARCHAR (MAX) and VARBINARY (MAX).” Limiting Result Sets by Using TABLESAMPLE – Examples Introduced in SQL Server 2005, TABLESAMPLE allows you to extract a sampling of rows from a table in the FROM clause. The rows retrieved are random and they are are not in any order. This sampling can be based on a percentage of number of rows. You can use TABLESAMPLE when only a sampling of rows is necessary for the application instead of a full result set. User Defined Functions (UDF) Limitations UDF have its own advantage and usage but in this article we will see the limitation of UDF. Things UDF can not do and why Stored Procedure are considered as more flexible then UDFs. Stored Procedure are more flexibility then User Defined Functions(UDF). However, this blog post is a good read to know what are the limitations of UDF. Change Database Compatible Level – Backward Compatibility For a long time SQL Server stayed on the compatibility level of 80 which is of SQL Server 2000. However, as soon as SQL Server 2005 introduced the issue of compatibility was quite a major issue. Since that time MS has been releasing the versions at every 2-3 years, changing compatibility is a ever popular topic. In this blog post, we learn how we can do the same using T-SQL. We can also do the same using SSMS and here is the blog post for the same: Change Database Compatible Level – Backward Compatibility – Part 2 – Management Studio. Constraint on VARCHAR(MAX) Field To Limit It Certain Length How can I limit the VARCHAR(MAX) field with maximum length of 12500 characters only. His Question was valid as our application was allowed 12500 characters. First of all – this requirement is bit strange but if someone wants to do the same, they can do it as described in this blog post. 2008 UNPIVOT Table Example Understanding UNPIVOT can be very complicated at times. In this blog post, I have attempted to explain the same concept in very simple words. Create Default Constraint Over Table Column A simple straight to script blog post – I still use this blog quite many times for my own reference. UDF – Get the Day of the Week Function It took me 4 iteration to find this very simple function which can immediately get the day of the week in a single line. 2009 Find Hostname and Current Logged In User Name There are two tricks listed in this blog post where users can find out the hostname and current logged user name immediately and very easily. Interesting Observation of Logon Trigger On All Servers When I was doing a project, I made an interesting observation of executing a logon trigger multiple times. It was absolutely unexpected for me! As I was logging only once, naturally, I was expecting the entry only once. However, it did it multiple times on different threads – indeed an eccentric phenomenon at first sight! Difference Between Candidate Keys and Primary Key One needs to be very careful in selecting the Primary Key as an incorrect selection can adversely impact the database architect and future normalization. For a Candidate Key to qualify as a Primary Key, it should be Non-NULL and unique in any domain. I have observed quite often that Primary Keys are seldom changed. I would like to have your feedback on not changing a Primary Key. Create Multiple Filegroup For Single Database Why should one create multiple file group for any database and what are the advantages of the same. In this blog post, I explain the same in detail. List All Objects Created on All Filegroups in Database In this blog post we discuss the essential question – “How can I find which object belongs to which filegroup. Is there any way to know this?” 2010 DATE and TIME in SQL Server 2008 When DATE is converted to DATETIME it adds the of midnight. When TIME is converted to DATETIME it adds the date of 1900 and it is something one wants to consider if you are going to run scripts from SQL Server 2008 to earlier version with CONVERT. Disabled Index and Update Statistics If you do not need a nonclustered index, I suggest you to drop it as keeping them disabled is an overhead on your system. This is because every time the statistics are updated for system all the statistics for disabled indexes are also updated. Precision of SMALLDATETIME – A 1 Minute Precision The precision of the datatype SMALLDATETIME is 1 minute. It discards the seconds by rounding up or rounding down any seconds greater than zero. 2011 Getting Columns Headers without Result Data – SET FMTONLY ON SET FMTONLY ON returns only metadata to the client. It can be used to test the format of the response without actually running the query. When this setting is ON the resultset only have headers of the results but no data. Copy Database from Instance to Another Instance – Copy Paste in SQL Server SQL Server has a feature which copy database from one database to another database and it can be automated as well using SSIS. Make sure you have SQL Server Agent Turned on as this feature will create a job. Puzzle – SELECT * vs SELECT COUNT(*) If you have ever wondered SELECT * gives error when executed alone but SELECT COUNT(*) does not. Why? in that case, you should read this blog post. Creating All New Database with Full Recovery Model This blog post is very based on very interesting story where the user wants to do something by default for every single new database created. Model database is a secret weapon which should be used very carefully and with proper evalution. If used carefully this can be a very much beneficiary when we need a newly created database behave in certain fashion. 2012 In year 2012 I had two interesting series ran on the blog. If there is no fun in learning, the learning becomes a burden. For the same reason, I had decided to build a three part quiz around SEQUENCE. The quiz was to identify the next value of the sequence. I encourage all of you to take part in this fun quiz. Guess the Next Value – Puzzle 1 Guess the Next Value – Puzzle 2 Guess the Next Value – Puzzle 3 Can anyone remember their final day of schooling?  This is probably a silly question because – of course you can!  Many people mark this as the most exciting, happiest day of their life.  It marks the end of testing, the end of following rules set by teachers, and the beginning of finally being able to earn money and work in your chosen field. Read five part series on developer training subject Developer Training - Importance and Significance - Part 1 Developer Training – Employee Morals and Ethics – Part 2 Developer Training – Difficult Questions and Alternative Perspective - Part 3 Developer Training – Various Options for Developer Training – Part 4 Developer Training – A Conclusive Summary- Part 5 Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Memory Lane, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Naming conventions for language file keys

  - by VirtuosiMedia

  What is your strategy for naming conventions for the keys in language files used for localization? We have a team that is going to conversion of a project to multiple languages and would like to have some guidelines to follow. As an example, usually the files end up being a series of key/value pairs, with the key being the placeholder in the template for the language specific value. 'Username': 'Username', 'Enter Username': 'Enter your username here'

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• Squid: caching *.swf with variables

  - by stfn

  I'd recently upgraded my Ubuntu 11.10 x64 server to 12.04. In this process Squid was updated from 2.7 to 3.1. Squid 3.1 has many different options witch broke my setup. So I completely removed squid 2.7 and 3.1 and started from scratch. Everything is now working as before except for 1 thing: caching of .swf files with ?/variables. Squid 3 sees a ? as dynamic content and does not cache it. For example, Squid 2.7 was caching the .swf file at http://ninjakiwi.com/Games/Tower-Defense/Play/Bloons-Tower-Defense-5.html and 3.1 is not. <object id="mov" name="movn" classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" width="800" height="620"> <param name="movie" value="http://www.ninjakiwifiles.com/Games/gameswfs/btd5.swf?v=160512-2"> <param name="allowscriptaccess" value="always"> <param name="bgcolor" value="#000000"> <param name="flashvars" value="file=http://www.ninjakiwifiles.com/Games/gameswfs/btd5-dat.swf?v=280512"> <p>Get Flash play Ninja Kiwi games.</p> </object> It is because of the "?v=160512-2" and "?v=280512" part. This line should be responsible for that: refresh_pattern -i (/cgi-bin/|\?) 0 0% 0 But disabling it still doesn't cache the .swf files. How do I configure Squid 3.1 to cache those files? My current config is: acl manager proto cache_object acl localhost src 127.0.0.1/32 ::1 acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1 acl SSL_ports port 443 acl Safe_ports port 80 # http acl Safe_ports port 21 # ftp acl Safe_ports port 443 # https acl Safe_ports port 70 # gopher acl Safe_ports port 210 # wais acl Safe_ports port 1025-65535 # unregistered ports acl Safe_ports port 280 # http-mgmt acl Safe_ports port 488 # gss-http acl Safe_ports port 591 # filemaker acl Safe_ports port 777 # multiling http acl CONNECT method CONNECT acl localnet src 192.168.2.0-192.168.2.255 acl localnet src 192.168.3.0-192.168.3.255 http_access allow manager localhost http_access deny manager http_access deny !Safe_ports http_access deny CONNECT !SSL_ports http_access allow localhost http_access allow localnet http_access deny all http_port 3128 cache_dir ufs /var/spool/squid 10240 16 256 maximum_object_size 100 MB coredump_dir /var/spool/squid3 refresh_pattern ^ftp: 1440 20% 10080 refresh_pattern ^gopher: 1440 0% 1440 refresh_pattern -i \.(gif|png|jpg|jpeg|ico)$ 10080 90% 43200 override-expire ignore-no-cache ignore-no-store ignore-private refresh_pattern -i \.(iso|avi|wav|mp3|mp4|mpeg|swf|flv|x-flv)$ 43200 90% 432000 override-expire ignore-no-cache ignore-no-store ignore-private refresh_pattern -i \.(deb|rpm|exe|zip|tar|tgz|ram|rar|bin|ppt|doc|tiff)$ 10080 90% 43200 override-expire ignore-no-cache ignore-no-store ignore-private refresh_pattern -i \.index.(html|htm)$ 0 40% 10080 refresh_pattern -i \.(html|htm|css|js)$ 1440 40% 40320 refresh_pattern Packages\.bz2$ 0 20% 4320 refresh-ims refresh_pattern Sources\.bz2$ 0 20% 4320 refresh-ims refresh_pattern Release\.gpg$ 0 20% 4320 refresh-ims refresh_pattern Release$ 0 20% 4320 refresh-ims refresh_pattern . 0 40% 40320 cache_effective_user proxy cache_effective_group proxy

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• REST to Objects in C#

  RESTful interfaces for web services are all the rage for many Web 2.0 sites.  If you want to consume these in a very simple fashion, LINQ to XML can do the job pretty easily in C#.  If you go searching for help on this, youll find a lot of incomplete solutions and fairly large toolkits and frameworks (guess how I know this) this quick article is meant to be a no fluff just stuff approach to making this work. POCO Objects Lets assume you have a Model that you want to suck data into from a RESTful web service.  Ideally this is a Plain Old CLR Object, meaning it isnt infected with any persistence or serialization goop.  It might look something like this: public class Entry { public int Id; public int UserId; public DateTime Date; public float Hours; public string Notes; public bool Billable;   public override string ToString() { return String.Format("[{0}] User: {1} Date: {2} Hours: {3} Notes: {4} Billable {5}", Id, UserId, Date, Hours, Notes, Billable); } } Not that this isnt a completely trivial object.  Lets look at the API for the service.  RESTful HTTP Service In this case, its TickSpots API, with the following sample output: <?xml version="1.0" encoding="UTF-8"?> <entries type="array"> <entry> <id type="integer">24</id> <task_id type="integer">14</task_id> <user_id type="integer">3</user_id> <date type="date">2008-03-08</date> <hours type="float">1.00</hours> <notes>Had trouble with tribbles.</notes> <billable>true</billable> # Billable is an attribute inherited from the task <billed>true</billed> # Billed is an attribute to track whether the entry has been invoiced <created_at type="datetime">Tue, 07 Oct 2008 14:46:16 -0400</created_at> <updated_at type="datetime">Tue, 07 Oct 2008 14:46:16 -0400</updated_at> # The following attributes are derived and provided for informational purposes: <user_email>[email protected]</user_email> <task_name>Remove converter assembly</task_name> <sum_hours type="float">2.00</sum_hours> <budget type="float">10.00</budget> <project_name>Realign dilithium crystals</project_name> <client_name>Starfleet Command</client_name> </entry> </entries> Im assuming in this case that I dont necessarily care about all of the data fields the service is returning I just need some of them for my applications purposes.  Thus, you can see there are more elements in the <entry> XML than I have in my Entry class. Get The XML with C# The next step is to get the XML.  The following snippet does the heavy lifting once you pass it the appropriate URL: protected XElement GetResponse(string uri) { var request = WebRequest.Create(uri) as HttpWebRequest; request.UserAgent = ".NET Sample"; request.KeepAlive = false;   request.Timeout = 15 * 1000;   var response = request.GetResponse() as HttpWebResponse;   if (request.HaveResponse == true && response != null) { var reader = new StreamReader(response.GetResponseStream()); return XElement.Parse(reader.ReadToEnd()); } throw new Exception("Error fetching data."); } This is adapted from the Yahoo Developer article on Web Service REST calls.  Once you have the XML, the last step is to get the data back as your POCO. Use LINQ-To-XML to Deserialize POCOs from XML This is done via the following code: public IEnumerable<Entry> List(DateTime startDate, DateTime endDate) { string additionalParameters = String.Format("start_date={0}&end_date={1}", startDate.ToShortDateString(), endDate.ToShortDateString()); string uri = BuildUrl("entries", additionalParameters);   XElement elements = GetResponse(uri);   var entries = from e in elements.Elements() where e.Name.LocalName == "entry" select new Entry { Id = int.Parse(e.Element("id").Value), UserId = int.Parse(e.Element("user_id").Value), Date = DateTime.Parse(e.Element("date").Value), Hours = float.Parse(e.Element("hours").Value), Notes = e.Element("notes").Value, Billable = bool.Parse(e.Element("billable").Value) }; return entries; }   For completeness, heres the BuildUrl method for my TickSpot API wrapper: // Change these to your settings protected const string projectDomain = "DOMAIN.tickspot.com"; private const string authParams = "[email protected]&password=MyTickSpotPassword";   protected string BuildUrl(string apiMethod, string additionalParams) { if (projectDomain.Contains("DOMAIN")) { throw new ApplicationException("You must update your domain in ProjectRepository.cs."); } if (authParams.Contains("MyTickSpotPassword")) { throw new ApplicationException("You must update your email and password in ProjectRepository.cs."); } return string.Format("https://{0}/api/{1}?{2}&{3}", projectDomain, apiMethod, authParams, additionalParams); } Thats it!  Now go forth and consume XML and map it to classes you actually want to work with.  Have fun! Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• MapReduce in DryadLINQ and PLINQ

  - by JoshReuben

  MapReduce See http://en.wikipedia.org/wiki/Mapreduce The MapReduce pattern aims to handle large-scale computations across a cluster of servers, often involving massive amounts of data. "The computation takes a set of input key/value pairs, and produces a set of output key/value pairs. The developer expresses the computation as two Func delegates: Map and Reduce. Map - takes a single input pair and produces a set of intermediate key/value pairs. The MapReduce function groups results by key and passes them to the Reduce function. Reduce - accepts an intermediate key I and a set of values for that key. It merges together these values to form a possibly smaller set of values. Typically just zero or one output value is produced per Reduce invocation. The intermediate values are supplied to the user's Reduce function via an iterator." the canonical MapReduce example: counting word frequency in a text file.     MapReduce using DryadLINQ see http://research.microsoft.com/en-us/projects/dryadlinq/ and http://connect.microsoft.com/Dryad DryadLINQ provides a simple and straightforward way to implement MapReduce operations. This The implementation has two primary components: A Pair structure, which serves as a data container. A MapReduce method, which counts word frequency and returns the top five words. The Pair Structure - Pair has two properties: Word is a string that holds a word or key. Count is an int that holds the word count. The structure also overrides ToString to simplify printing the results. The following example shows the Pair implementation. public struct Pair { private string word; private int count; public Pair(string w, int c) { word = w; count = c; } public int Count { get { return count; } } public string Word { get { return word; } } public override string ToString() { return word + ":" + count.ToString(); } } The MapReduce function  that gets the results. the input data could be partitioned and distributed across the cluster. 1. Creates a DryadTable<LineRecord> object, inputTable, to represent the lines of input text. For partitioned data, use GetPartitionedTable<T> instead of GetTable<T> and pass the method a metadata file. 2. Applies the SelectMany operator to inputTable to transform the collection of lines into collection of words. The String.Split method converts the line into a collection of words. SelectMany concatenates the collections created by Split into a single IQueryable<string> collection named words, which represents all the words in the file. 3. Performs the Map part of the operation by applying GroupBy to the words object. The GroupBy operation groups elements with the same key, which is defined by the selector delegate. This creates a higher order collection, whose elements are groups. In this case, the delegate is an identity function, so the key is the word itself and the operation creates a groups collection that consists of groups of identical words. 4. Performs the Reduce part of the operation by applying Select to groups. This operation reduces the groups of words from Step 3 to an IQueryable<Pair> collection named counts that represents the unique words in the file and how many instances there are of each word. Each key value in groups represents a unique word, so Select creates one Pair object for each unique word. IGrouping.Count returns the number of items in the group, so each Pair object's Count member is set to the number of instances of the word. 5. Applies OrderByDescending to counts. This operation sorts the input collection in descending order of frequency and creates an ordered collection named ordered. 6. Applies Take to ordered to create an IQueryable<Pair> collection named top, which contains the 100 most common words in the input file, and their frequency. Test then uses the Pair object's ToString implementation to print the top one hundred words, and their frequency.   public static IQueryable<Pair> MapReduce( string directory, string fileName, int k) { DryadDataContext ddc = new DryadDataContext("file://" + directory); DryadTable<LineRecord> inputTable = ddc.GetTable<LineRecord>(fileName); IQueryable<string> words = inputTable.SelectMany(x => x.line.Split(' ')); IQueryable<IGrouping<string, string>> groups = words.GroupBy(x => x); IQueryable<Pair> counts = groups.Select(x => new Pair(x.Key, x.Count())); IQueryable<Pair> ordered = counts.OrderByDescending(x => x.Count); IQueryable<Pair> top = ordered.Take(k);   return top; }   To Test: IQueryable<Pair> results = MapReduce(@"c:\DryadData\input", "TestFile.txt", 100); foreach (Pair words in results) Debug.Print(words.ToString());   Note: DryadLINQ applications can use a more compact way to represent the query: return inputTable         .SelectMany(x => x.line.Split(' '))         .GroupBy(x => x)         .Select(x => new Pair(x.Key, x.Count()))         .OrderByDescending(x => x.Count)         .Take(k);     MapReduce using PLINQ The pattern is relevant even for a single multi-core machine, however. We can write our own PLINQ MapReduce in a few lines. the Map function takes a single input value and returns a set of mapped values àLINQ's SelectMany operator. These are then grouped according to an intermediate key à LINQ GroupBy operator. The Reduce function takes each intermediate key and a set of values for that key, and produces any number of outputs per key à LINQ SelectMany again. We can put all of this together to implement MapReduce in PLINQ that returns a ParallelQuery<T> public static ParallelQuery<TResult> MapReduce<TSource, TMapped, TKey, TResult>( this ParallelQuery<TSource> source, Func<TSource, IEnumerable<TMapped>> map, Func<TMapped, TKey> keySelector, Func<IGrouping<TKey, TMapped>, IEnumerable<TResult>> reduce) { return source .SelectMany(map) .GroupBy(keySelector) .SelectMany(reduce); } the map function takes in an input document and outputs all of the words in that document. The grouping phase groups all of the identical words together, such that the reduce phase can then count the words in each group and output a word/count pair for each grouping: var files = Directory.EnumerateFiles(dirPath, "*.txt").AsParallel(); var counts = files.MapReduce( path => File.ReadLines(path).SelectMany(line => line.Split(delimiters)), word => word, group => new[] { new KeyValuePair<string, int>(group.Key, group.Count()) });

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• Customer won't decide, how to deal?

  - by Crazy Eddie

  I write software that involves the use of measured quantities, many input by the user, most displayed, that are fed into calculation models to simulate various physical thing-a-majigs. We have created a data type that allows us to associate a numeric value with a unit, we call these "quantities" (big duh). Quantities and units are unique to dimension. You can't attach kilogram to a length for example. Math on quantities does automatic unit conversion to SI and the type is dimension safe (you can't assign a weight to a pressure for example). Custom UI components have been developed that display the value and its unit and/or allow the user to edit them. Dimensionless quantities, having no units, are a single, custom case implemented within the system. There's a set of related quantities such that our target audience apparently uses them interchangeably. The quantities are used in special units that embed the conversion factors for the related quantity dimensions...in other words, when using these units converting from one to another simply involves multiplying the value by 1 to the dimensional difference. However, conversion to/from the calculation system (SI) still involves these factors. One of these related quantities is a dimensionless one that represents a ratio. I simply can't get the "customer" to recognize the necessity of distinguishing these values and their use. They've picked one and want to use it everywhere, customizing the way we deal with it in special places. In this case they've picked one of the dimensions that has a unit...BUT, they don't want there to be a unit (GRR!!!). This of course is causing us to implement these special overrides for our UI elements and such. That of course is often times forgotten and worse...after a couple months everyone forgets why it was necessary and why we're using this dimensional value, calling it the wrong thing, and disabling the unit. I could just ignore the "customer" and implement the type as the dimensionless quantity, which makes most sense. However, that leaves the team responsible for figuring it out when they've given us a formula using one of the other quantities. We have to not only figure out that it's happening, we have to decide what to do. This isn't a trivial deal. The other option is just to say to hell with it, do it the customer's way, and let it waste continued time and effort because it's just downright confusing as hell. However, I can't count the amount of times someone has said, "Why is this being done this way, it makes no sense at all," and the team goes off the deep end trying to figure it out. What would you do? Currently I'm still attempting to convince them that even if they use terms interchangeably, we at the least can't do that within the product discussion. Don't have high hopes though.

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• PostSharp, Obfuscation, and IL

  - by simonc

  Aspect-oriented programming (AOP) is a relatively new programming paradigm. Originating at Xerox PARC in 1994, the paradigm was first made available for general-purpose development as an extension to Java in 2001. From there, it has quickly been adapted for use in all the common languages used today. In the .NET world, one of the primary AOP toolkits is PostSharp. Attributes and AOP Normally, attributes in .NET are entirely a metadata construct. Apart from a few special attributes in the .NET framework, they have no effect whatsoever on how a class or method executes within the CLR. Only by using reflection at runtime can you access any attributes declared on a type or type member. PostSharp changes this. By declaring a custom attribute that derives from PostSharp.Aspects.Aspect, applying it to types and type members, and running the resulting assembly through the PostSharp postprocessor, you can essentially declare 'clever' attributes that change the behaviour of whatever the aspect has been applied to at runtime. A simple example of this is logging. By declaring a TraceAttribute that derives from OnMethodBoundaryAspect, you can automatically log when a method has been executed: public class TraceAttribute : PostSharp.Aspects.OnMethodBoundaryAspect { public override void OnEntry(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Entering {0}.{1}.", method.DeclaringType.FullName, method.Name)); } public override void OnExit(MethodExecutionArgs args) { MethodBase method = args.Method; System.Diagnostics.Trace.WriteLine( String.Format( "Leaving {0}.{1}.", method.DeclaringType.FullName, method.Name)); } } [Trace] public void MethodToLog() { ... } Now, whenever MethodToLog is executed, the aspect will automatically log entry and exit, without having to add the logging code to MethodToLog itself. PostSharp Performance Now this does introduce a performance overhead - as you can see, the aspect allows access to the MethodBase of the method the aspect has been applied to. If you were limited to C#, you would be forced to retrieve each MethodBase instance using Type.GetMethod(), matching on the method name and signature. This is slow. Fortunately, PostSharp is not limited to C#. It can use any instruction available in IL. And in IL, you can do some very neat things. Ldtoken C# allows you to get the Type object corresponding to a specific type name using the typeof operator: Type t = typeof(Random); The C# compiler compiles this operator to the following IL: ldtoken [mscorlib]System.Random call class [mscorlib]System.Type [mscorlib]System.Type::GetTypeFromHandle( valuetype [mscorlib]System.RuntimeTypeHandle) The ldtoken instruction obtains a special handle to a type called a RuntimeTypeHandle, and from that, the Type object can be obtained using GetTypeFromHandle. These are both relatively fast operations - no string lookup is required, only direct assembly and CLR constructs are used. However, a little-known feature is that ldtoken is not just limited to types; it can also get information on methods and fields, encapsulated in a RuntimeMethodHandle or RuntimeFieldHandle: // get a MethodBase for String.EndsWith(string) ldtoken method instance bool [mscorlib]System.String::EndsWith(string) call class [mscorlib]System.Reflection.MethodBase [mscorlib]System.Reflection.MethodBase::GetMethodFromHandle( valuetype [mscorlib]System.RuntimeMethodHandle) // get a FieldInfo for the String.Empty field ldtoken field string [mscorlib]System.String::Empty call class [mscorlib]System.Reflection.FieldInfo [mscorlib]System.Reflection.FieldInfo::GetFieldFromHandle( valuetype [mscorlib]System.RuntimeFieldHandle) These usages of ldtoken aren't usable from C# or VB, and aren't likely to be added anytime soon (Eric Lippert's done a blog post on the possibility of adding infoof, methodof or fieldof operators to C#). However, PostSharp deals directly with IL, and so can use ldtoken to get MethodBase objects quickly and cheaply, without having to resort to string lookups. The kicker However, there are problems. Because ldtoken for methods or fields isn't accessible from C# or VB, it hasn't been as well-tested as ldtoken for types. This has resulted in various obscure bugs in most versions of the CLR when dealing with ldtoken and methods, and specifically, generic methods and methods of generic types. This means that PostSharp was behaving incorrectly, or just plain crashing, when aspects were applied to methods that were generic in some way. So, PostSharp has to work around this. Without using the metadata tokens directly, the only way to get the MethodBase of generic methods is to use reflection: Type.GetMethod(), passing in the method name as a string along with information on the signature. Now, this works fine. It's slower than using ldtoken directly, but it works, and this only has to be done for generic methods. Unfortunately, this poses problems when the assembly is obfuscated. PostSharp and Obfuscation When using ldtoken, obfuscators don't affect how PostSharp operates. Because the ldtoken instruction directly references the type, method or field within the assembly, it is unaffected if the name of the object is changed by an obfuscator. However, the indirect loading used for generic methods was breaking, because that uses the name of the method when the assembly is put through the PostSharp postprocessor to lookup the MethodBase at runtime. If the name then changes, PostSharp can't find it anymore, and the assembly breaks. So, PostSharp needs to know about any changes an obfuscator does to an assembly. The way PostSharp does this is by adding another layer of indirection. When PostSharp obfuscation support is enabled, it includes an extra 'name table' resource in the assembly, consisting of a series of method & type names. When PostSharp needs to lookup a method using reflection, instead of encoding the method name directly, it looks up the method name at a fixed offset inside that name table: MethodBase genericMethod = typeof(ContainingClass).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: get_Prop1 21: set_Prop1 22: DoFoo 23: GetWibble When the assembly is later processed by an obfuscator, the obfuscator can replace all the method and type names within the name table with their new name. That way, the reflection lookups performed by PostSharp will now use the new names, and everything will work as expected: MethodBase genericMethod = typeof(#kGy).GetMethod(GetNameAtIndex(22)); PostSharp.NameTable resource: ... 20: #kkA 21: #zAb 22: #EF5a 23: #2tg As you can see, this requires direct support by an obfuscator in order to perform these rewrites. Dotfuscator supports it, and now, starting with SmartAssembly 6.6.4, SmartAssembly does too. So, a relatively simple solution to a tricky problem, with some CLR bugs thrown in for good measure. You don't see those every day! Cross posted from Simple Talk.

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• On the art of self-promotion

  - by Tony Davis

  I attended Brent Ozar’s Building the Fastest SQL Servers session at Tech Ed last week, and found myself engulfed in a ‘perfect storm’ of excellent technical and presentational skills coupled with an astute awareness of the value of promoting one’s work. I spend a lot of time at such events talking to developers and DBAs about the value of blogging and writing articles, and my impression is that some could benefit from a touch less modesty and a little more self-promotion. I sense a reticence in many would-be writers. Is what I have to say important enough? Haven’t far more qualified and established commentators, MVPs and so on, already said it? While it’s a good idea to pick reasonably fresh and interesting topics, it’s more important not to let such fears lead to writer’s block. In the eyes of any future employer, your published writing is an extension of your resume. They will not care that a certain MVP knows how to solve problem x, but they will be very interested to see that you have tackled that same problem, and solved it in your own way, and described the process in your own voice. In your current job, your writing is one of the ways you can express to your peers, and to the organization as a whole, the value of what you contribute. Many Developers and DBAs seem to rely on the idea that their work will speak for itself, and that their skill shines out from it. Unfortunately, this isn’t always true. Many Development DBAs, for example, will be painfully aware of the massive effort involved in tuning and adding resilience to rapidly developed applications. However, others in the organization who are unaware of what’s involved in getting an application that is ‘done’ ready for production may dismiss such efforts as fussiness or conservatism. At the dark end of the development cycle, chickens come home to roost, but their droppings tend to land on those trying to clear up the mess. My advice is this: next time you fix a bug or improve the resilience or performance of a database or application, make sure that you use team meetings, informal discussions and so on to ensure that people understand what the problem was and what you had to do to fix it. Use your blog to describe, generally, the process you adopted, the resources you used and the insights that came from your work. Encourage your colleagues to do the same. By spreading the art of self-promotion to everyone involved in an IT project, we get a better idea of the extent of the work and the value of the contribution of all the team members. As always, we’d love to hear what you think. This very week, Simple-talk launches its new blogging platform. If any of this has moved you to ‘throw your hat into the ring’, drop us a mail at [email protected]. Cheers, Tony.

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• On the art of self-promotion

  - by Tony Davis

  I attended Brent Ozar's Building the Fastest SQL Servers session at Tech Ed last week, and found myself engulfed in a 'perfect storm' of excellent technical and presentational skills coupled with an astute awareness of the value of promoting one's work. I spend a lot of time at such events talking to developers and DBAs about the value of blogging and writing articles, and my impression is that some could benefit from a touch less modesty and a little more self-promotion. I sense a reticence in many would-be writers. Is what I have to say important enough? Haven't far more qualified and established commentators, MVPs and so on, already said it? While it's a good idea to pick reasonably fresh and interesting topics, it's more important not to let such fears lead to writer's block. In the eyes of any future employer, your published writing is an extension of your resume. They will not care that a certain MVP knows how to solve problem x, but they will be very interested to see that you have tackled that same problem, and solved it in your own way, and described the process in your own voice. In your current job, your writing is one of the ways you can express to your peers, and to the organization as a whole, the value of what you contribute. Many Developers and DBAs seem to rely on the idea that their work will speak for itself, and that their skill shines out from it. Unfortunately, this isn't always true. Many Development DBAs, for example, will be painfully aware of the massive effort involved in tuning and adding resilience to rapidly developed applications. However, others in the organization who are unaware of what's involved in getting an application that is 'done' ready for production may dismiss such efforts as fussiness or conservatism. At the dark end of the development cycle, chickens come home to roost, but their droppings tend to land on those trying to clear up the mess. My advice is this: next time you fix a bug or improve the resilience or performance of a database or application, make sure that you use team meetings, informal discussions and so on to ensure that people understand what the problem was and what you had to do to fix it. Use your blog to describe, generally, the process you adopted, the resources you used and the insights that came from your work. Encourage your colleagues to do the same. By spreading the art of self-promotion to everyone involved in an IT project, we get a better idea of the extent of the work and the value of the contribution of all the team members. As always, we'd love to hear what you think. This very week, Simple-talk launches its new blogging platform. If any of this has moved you to 'throw your hat into the ring', drop us a mail at [email protected]. Cheers, Tony.

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• Protecting Cookies: Once and For All

  - by Your DisplayName here!

  Every once in a while you run into a situation where you need to temporarily store data for a user in a web app. You typically have two options here – either store server-side or put the data into a cookie (if size permits). When you need web farm compatibility in addition – things become a little bit more complicated because the data needs to be available on all nodes. In my case I went for a cookie – but I had some requirements Cookie must be protected from eavesdropping (sent only over SSL) and client script Cookie must be encrypted and signed to be protected from tampering with Cookie might become bigger than 4KB – some sort of overflow mechanism would be nice I really didn’t want to implement another cookie protection mechanism – this feels wrong and btw can go wrong as well. WIF to the rescue. The session management feature already implements the above requirements but is built around de/serializing IClaimsPrincipals into cookies and back. But if you go one level deeper you will find the CookieHandler and CookieTransform classes which contain all the needed functionality. public class ProtectedCookie {     private List<CookieTransform> _transforms;     private ChunkedCookieHandler _handler = new ChunkedCookieHandler();     // DPAPI protection (single server)     public ProtectedCookie()     {         _transforms = new List<CookieTransform>             {                 new DeflateCookieTransform(),                 new ProtectedDataCookieTransform()             };     }     // RSA protection (load balanced)     public ProtectedCookie(X509Certificate2 protectionCertificate)     {         _transforms = new List<CookieTransform>             {                 new DeflateCookieTransform(),                 new RsaSignatureCookieTransform(protectionCertificate),                 new RsaEncryptionCookieTransform(protectionCertificate)             };     }     // custom transform pipeline     public ProtectedCookie(List<CookieTransform> transforms)     {         _transforms = transforms;     }     public void Write(string name, string value, DateTime expirationTime)     {         byte[] encodedBytes = EncodeCookieValue(value);         _handler.Write(encodedBytes, name, expirationTime);     }     public void Write(string name, string value, DateTime expirationTime, string domain, string path)     {         byte[] encodedBytes = EncodeCookieValue(value);         _handler.Write(encodedBytes, name, path, domain, expirationTime, true, true, HttpContext.Current);     }     public string Read(string name)     {         var bytes = _handler.Read(name);         if (bytes == null || bytes.Length == 0)         {             return null;         }         return DecodeCookieValue(bytes);     }     public void Delete(string name)     {         _handler.Delete(name);     }     protected virtual byte[] EncodeCookieValue(string value)     {         var bytes = Encoding.UTF8.GetBytes(value);         byte[] buffer = bytes;         foreach (var transform in _transforms)         {             buffer = transform.Encode(buffer);         }         return buffer;     }     protected virtual string DecodeCookieValue(byte[] bytes)     {         var buffer = bytes;         for (int i = _transforms.Count; i > 0; i—)         {             buffer = _transforms[i - 1].Decode(buffer);         }         return Encoding.UTF8.GetString(buffer);     } } HTH

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• Difference between IN and FIND_IN_SET

  - by Madhan ayyasamy

  Hi Friends,You may be confused with IN() and FIND_IN_SET() MYSQL functions. There are specific case/situation for both functions where to use which Mysql function. Look at below explanation about IN() and FIND_IN_SET()IN() : This function is used when you have a list of possible values and a single value in your database.Example: WHERE memberid IN (1,2,3)FIND_IN_SET() : This function is used where you have comma separated list of values stored in database and want to see if a certain value exists in that comma seperated list.Example: WHERE FIND_IN_SET( ‘table column name like id’, 'dynamic idlist' )

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• Have you used the ExecutionValue and ExecValueVariable properties?

  The ExecutionValue execution value property and it’s friend ExecValueVariable are a much undervalued feature of SSIS, and many people I talk to are not even aware of their existence, so I thought I’d try and raise their profile a bit. The ExecutionValue property is defined on the base object Task, so all tasks have it available, but it is up to the task developer to do something useful with it. The basic idea behind it is that it allows the task to return something useful and interesting about what it has performed, in addition to the standard success or failure result. The best example perhaps is the Execute SQL Task which uses the ExecutionValue property to return the number of rows affected by the SQL statement(s). This is a very useful feature, something people often want to capture into a variable, and start using the result set options to do. Unfortunately we cannot read the value of a task property at runtime from within a SSIS package, so the ExecutionValue property on its own is a bit of a let down, but enter the ExecValueVariable and we have the perfect marriage. The ExecValueVariable is another property exposed through the task (TaskHost), which lets us select a SSIS package variable. What happens now is that when the task sets the ExecutionValue, the interesting value is copied into the variable we set on the ExecValueVariable property, and a variable is something we can access and do something with. So put simply if the ExecutionValue property value is of interest, make sure you create yourself a package variable and set the name as the ExecValueVariable. Have  look at the 3 step guide below: 1 Configure your task as normal, for example the Execute SQL Task, which here calls a stored procedure to do some updates. 2 Create variable of a suitable type to match the ExecutionValue, an integer is used to match the result we want to capture, the number of rows. 3 Set the ExecValueVariable for the task, just select the variable we created in step 2. You need to do this in Properties grid for the task (Short-cut key, select the task and press F4) Now when we execute the sample task above, our variable UpdateQueueRowCount will get the number of rows we updated in our Execute SQL Task. I’ve tried to collate a list of tasks that return something useful via the ExecutionValue and ExecValueVariable mechanism, but the documentation isn’t always great. Task ExecutionValue Description Execute SQL Task Returns the number of rows affected by the SQL statement or statements. File System Task Returns the number of successful operations performed by the task. File Watcher Task Returns the full path of the file found Transfer Error Messages Task Returns the number of error messages that have been transferred Transfer Jobs Task Returns the number of jobs that are transferred Transfer Logins Task Returns the number of logins transferred Transfer Master Stored Procedures Task Returns the number of stored procedures transferred Transfer SQL Server Objects Task Returns the number of objects transferred WMI Data Reader Task Returns an object that contains the results of the task. Not exactly clear, but I assume it depends on the WMI query used.

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• SOA Suite Integration: Part 3: Loading files

  - by Anthony Shorten

  One of the most common scenarios in SOA Integration is the loading of a file into the product from an external source. In Oracle SOA Suite there is a File Adapter that can process many file types into your BPEL process. For this example I will use the File Adapter to load a file of user and emails to update the user object within the Oracle Utilities Application Framework. Remember you can repeat this process with other objects and other file types. Again I am illustrating the ease of integration. The first thing is to create an empty BPEL process that will hold our flow. In Oracle JDeveloper this can be achieved by specifying the Define Service Later template (as other templates have predefined inputs and outputs and in this case we want to specify those). So I will create simpleFileLoad process to house our process. You will start with an empty canvas so you need to first specify the load part of the process using the File Adapter. Select the File Adapter from the Component Palette under BPEL Services and drag and drop it to the left side Partner Links (left is input). You name the Service. In this case I chose LoadFile. Press Next. We will define the interface as part of the wizard so select Define from operation and schema (specified later). Press Next. We are going to choose Read File to denote that we will read the file and specify the default Operation Name as Read. Press Next. The next step is to tell the Adapter the location of the files, how to process them and what to do with them after they have been processed. I am using hardcoded locations in this example but you can have logical locations as well. Press Next. I am now going to tell the adapter how to recognize the files I want to load. In my case I am using CSV files and more importantly I am tell the adapter to run the process for each record in the file it encounters. Press Next. Now, I tell the adapter how often I want to poll for the files. I have taken the defaults. Press Next. At this stage I have no explanation of the format of the input. So I am going to invoke the Native Format Wizard which will guide me through the process of creating the file input format. Clicking the purple cog icon will start the wizard. After an introduction screen (not shown), you specify the format of the input file. The File Adapter supports multiple format types. For this example, I will use Delimited as I am going to load a CSV file. Press Next. The best way for the wizard to work is with a sample. I have a sample file and the wizard will ask how much of the file to use as a template. I will use the defaults. Note: If you are using a language that has other languages other than US-ASCII, it is at this point you specify the character set to use.  Press Next. The sample contains multiple instances of a single record type. The wizard supports complex types as well. We will use the appropriate setting for our file. Press Next. You have to specify the file element and the record element. This will be used by the input wizard to translate the CSV data into an XML structure (this will make sense later). I am using LoadUsers as my file delimiter (root element) and User Record as my record root element. Press Next. As the file is CSV the delimiter is "," so I will also specify that the End Of Line (EOL) indicator indicates the end of a record. Press Next. Up until this point your have not given the columns their names. In my case my sample includes the column names in the first record. This is not always the case but you can specify the names and formats of columns in this dialog (not shown). Press Next. The wizard now generates the schema for the input file. You can specify a name for the schema. I have used userupdate.xsd. We want to verify the schema so press Test. You can test the schema by specifying an input sample. and pressing the green play button. You will see the delimiters you specified earlier for the file and the records. Press Ok to continue. A confirmation screen will be displayed showing you the location of the schema in your project. Press Finish to return to the File Adapter configuration. You will now see the schema and elements prepopulated from the wizard. Press Next. The File Adapter configuration is now complete. Press Finish. Now you need to receive the input from the LoadFile component so we need to place a Receive node in the BPEL process by drag and dropping the Receive component from the Component Palette under BPEL Constructs onto the BPEL process. We link the receive process with the LoadFile component by dragging the left most connect node of the Receive node to the LoadFile component. Once the link is established you need to name the Receive node appropriately and as in the post of the last part of this series you need to generate input variables for the BPEL process to hold the input records in. You need to now add the product Web Service. The process is the same as described in the post of the last part of this series. You drop the Web Service BPEL Service onto the right side of the process and fill in the details of the WSDL URL . You also have to add an Invoke node to call the service and generate the input and outputs variables for the call in the Invoke node. Now, to get the inputs from File to the service. You have to use a Transform (you can use an Assign action but a Transform action is more flexible). You drag and drop the Transform component from the Component Palette under Oracle Extensions and place it between the Receive and Invoke nodes. We name the Transform Node, Mapper File and associate the source of the mapping the schema from the Receive node and the output will be the input variable from the Invoke node. We now build the transform. We first map the user and email attributes by drag and drop the elements from the left to the right. The reason we needed to use the transform is that we will be telling the AS-User service that we want to issue an update action. Remember when we registered the service we actually used Read as the default. If we do not otherwise inform the service to use the Update action it will use the Read action instead (which is not desired). To specify the update action you need to click on the transactionType node on the right and select Set Text to set the action. You need to specify the transactionType of UPD (for update). The mapping is now complete. The final BPEL process is ready for deployment. You then deploy the BPEL process to the server and to test the service by simply dropping a file, in the same pattern/name as you specified, in the directory you specified in the File Adapter. You will see each record as a separate instance entry in the Fusion Middleware Control console. You can now load files into the product. You can repeat this process for each type of file to process. While this was a simple example it illustrates the method of loading data can be achieved using SOA Suite in conjunction with our products.

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• Update Variable in TeamCity powershell script

  - by Jake Rote

  I am try to update an enviroment variable in teamcity using powershell code. But it does not update the value of the variable. How can i do this? My current code is (It gets the currentBuildNumber fine: $currentBuildNumber = "%env.currentBuildNumber%" $newBuildNumber = "" Write-Output $currentBuildNumber If ($currentBuildNumber.StartsWith("%MajorVersion%") -eq "True") { $parts = $currentBuildNumber.Split(".") $parts[2] = ([int]::Parse($parts[2]) + 1) + "" $newBuildNumber = $parts -join "." } Else { $newBuildNumber = '%MajorVersion%.1' } //What I have tried $env:currentBuildNumber = $newBuildNumber Write-Host "##teamcity[env.currentBuildNumber '$newBuildNumber']" Write-Host "##teamcity[setParameter name='currentBuildNumber' value='$newBuildNumber']"

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• Handy Generic JQuery Functions

  - by Steve Wilkes

  I was a bit of a late-comer to the JQuery party, but now I've been using it for a while it's given me a host of options for adding extra flair to the client side of my applications. Here's a few generic JQuery functions I've written which can be used to add some neat little features to a page. Just call any of them from a document ready function. Apply JQuery Themeroller Styles to all Page Buttons   The JQuery Themeroller is a great tool for creating a theme for a site based on colours and styles for particular page elements. The JQuery.UI library then provides a set of functions which allow you to apply styles to page elements. This function applies a JQuery Themeroller style to all the buttons on a page - as well as any elements which have a button class applied to them - and then makes the mouse pointer turn into a cursor when you mouse over them: function addCursorPointerToButtons() {     $("button, input[type='submit'], input[type='button'], .button") .button().css("cursor", "pointer"); } Automatically Remove the Default Value from a Select Box   Required drop-down select boxes often have a default option which reads 'Please select...' (or something like that), but once someone has selected a value, there's no need to retain that. This function removes the default option from any select boxes on the page which have a data-val-remove-default attribute once one of the non-default options has been chosen: function removeDefaultSelectOptionOnSelect() {     $("select[data-val-remove-default='']").change(function () {         var sel = $(this);         if (sel.val() != "") { sel.children("option[value='']:first").remove(); }     }); } Automatically add a Required Label and Stars to a Form   It's pretty standard to have a little * next to required form field elements. This function adds the text * Required to the top of the first form on the page, and adds *s to any element within the form with the class editor-label and a data-val-required attribute: function addRequiredFieldLabels() {     var elements = $(".editor-label[data-val-required='']");     if (!elements.length) { return; }     var requiredString = "<div class='editor-required-key'>* Required</div>";     var prependString = "<span class='editor-required-label'> * </span>"; var firstFormOnThePage = $("form:first");     if (!firstFormOnThePage.children('div.editor-required-key').length) {         firstFormOnThePage.prepend(requiredString);     }     elements.each(function (index, value) { var formElement = $(this);         if (!formElement.children('span.editor-required-label').length) {             formElement.prepend(prependString);         }     }); } I hope those come in handy :)

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• REST to Objects in C#

  RESTful interfaces for web services are all the rage for many Web 2.0 sites.  If you want to consume these in a very simple fashion, LINQ to XML can do the job pretty easily in C#.  If you go searching for help on this, youll find a lot of incomplete solutions and fairly large toolkits and frameworks (guess how I know this) this quick article is meant to be a no fluff just stuff approach to making this work. POCO Objects Lets assume you have a Model that you want to suck data into from a RESTful web service.  Ideally this is a Plain Old CLR Object, meaning it isnt infected with any persistence or serialization goop.  It might look something like this: public class Entry { public int Id; public int UserId; public DateTime Date; public float Hours; public string Notes; public bool Billable;   public override string ToString() { return String.Format("[{0}] User: {1} Date: {2} Hours: {3} Notes: {4} Billable {5}", Id, UserId, Date, Hours, Notes, Billable); } } Not that this isnt a completely trivial object.  Lets look at the API for the service.  RESTful HTTP Service In this case, its TickSpots API, with the following sample output: <?xml version="1.0" encoding="UTF-8"?> <entries type="array"> <entry> <id type="integer">24</id> <task_id type="integer">14</task_id> <user_id type="integer">3</user_id> <date type="date">2008-03-08</date> <hours type="float">1.00</hours> <notes>Had trouble with tribbles.</notes> <billable>true</billable> # Billable is an attribute inherited from the task <billed>true</billed> # Billed is an attribute to track whether the entry has been invoiced <created_at type="datetime">Tue, 07 Oct 2008 14:46:16 -0400</created_at> <updated_at type="datetime">Tue, 07 Oct 2008 14:46:16 -0400</updated_at> # The following attributes are derived and provided for informational purposes: <user_email>[email protected]</user_email> <task_name>Remove converter assembly</task_name> <sum_hours type="float">2.00</sum_hours> <budget type="float">10.00</budget> <project_name>Realign dilithium crystals</project_name> <client_name>Starfleet Command</client_name> </entry> </entries> Im assuming in this case that I dont necessarily care about all of the data fields the service is returning I just need some of them for my applications purposes.  Thus, you can see there are more elements in the <entry> XML than I have in my Entry class. Get The XML with C# The next step is to get the XML.  The following snippet does the heavy lifting once you pass it the appropriate URL: protected XElement GetResponse(string uri) { var request = WebRequest.Create(uri) as HttpWebRequest; request.UserAgent = ".NET Sample"; request.KeepAlive = false;   request.Timeout = 15 * 1000;   var response = request.GetResponse() as HttpWebResponse;   if (request.HaveResponse == true && response != null) { var reader = new StreamReader(response.GetResponseStream()); return XElement.Parse(reader.ReadToEnd()); } throw new Exception("Error fetching data."); } This is adapted from the Yahoo Developer article on Web Service REST calls.  Once you have the XML, the last step is to get the data back as your POCO. Use LINQ-To-XML to Deserialize POCOs from XML This is done via the following code: public IEnumerable<Entry> List(DateTime startDate, DateTime endDate) { string additionalParameters = String.Format("start_date={0}&end_date={1}", startDate.ToShortDateString(), endDate.ToShortDateString()); string uri = BuildUrl("entries", additionalParameters);   XElement elements = GetResponse(uri);   var entries = from e in elements.Elements() where e.Name.LocalName == "entry" select new Entry { Id = int.Parse(e.Element("id").Value), UserId = int.Parse(e.Element("user_id").Value), Date = DateTime.Parse(e.Element("date").Value), Hours = float.Parse(e.Element("hours").Value), Notes = e.Element("notes").Value, Billable = bool.Parse(e.Element("billable").Value) }; return entries; }   For completeness, heres the BuildUrl method for my TickSpot API wrapper: // Change these to your settings protected const string projectDomain = "DOMAIN.tickspot.com"; private const string authParams = "[email protected]&password=MyTickSpotPassword";   protected string BuildUrl(string apiMethod, string additionalParams) { if (projectDomain.Contains("DOMAIN")) { throw new ApplicationException("You must update your domain in ProjectRepository.cs."); } if (authParams.Contains("MyTickSpotPassword")) { throw new ApplicationException("You must update your email and password in ProjectRepository.cs."); } return string.Format("https://{0}/api/{1}?{2}&{3}", projectDomain, apiMethod, authParams, additionalParams); } Thats it!  Now go forth and consume XML and map it to classes you actually want to work with.  Have fun! Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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• How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?

  - by sathya

  How to Overcome or fix MIXED_DML_OPERATION error in Salesforce APEX without future method ?MIXED_DML_OPERATION :-one of the worst issues we have ever faced :)While trying to perform DML operation on a setup object and non-setup object in a single action you will face this error.Following are the solutions I tried and the final one worked out :-1. perform the 1st objects DML on normal apex method. Then Call the 2nd objects DML through a future method.    Drawback :- You cant get a response from the future method as its context is different and because its executing asynchronously and that its static.2. Tried the following option but it didnt work :-    1. perform the dml operation on the normal apex method.    2. tried calling the 2nd dml from trigger thinking that it would be in a different context. But it didnt work.    3. Some suggestions were given in some blogs that we could try System.runas()   Unfortunately that works only for test class.   4. Finally achieved it with response synchronously through the following solution :-    a. Created 2 apex:commandbuttons :-        1. <apex:commandButton value="Save and Send Activation Email" action="{!CreateContact}"  rerender="junkpanel" oncomplete="callSimulateUserSave()">            Note :- Oncomplete will not work if you dont have a rerender attribute. So just try refreshing a junk panel.        2. <apex:commandButton value="SimulateUserSave" id="SimulateUserSave" action="{!SaveUser}"  style="display:none;margin-left:5px;"/>        Have a junk panel as well just for rerendering  :-        <apex:outputPanel id="junkpanel"></apex:outputPanel>    b. Created this javascript function which is called from first button's oncomplete and clicks the second button :-                function callSimulateUserSave()                {                    // Specify the id of the button that needs to be clicked. This id is based on the Apex Component Hierarchy.                    // You will not get this value if you dont have the id attribute in the button which needs to be clicked from javascript                    // If you have any doubt in getting this value. Just hover over the button using Chrome developer tools to get the id.                    // But it will show like theForm:SimulateUserSave but you need to replace the colon with a dot here.                    // Note :- I have given display:none in the style of the second button to make sure that, it is not visible for the user.                    var mybtn=document.getElementById('{!$Component.theForm.SimulateUserSave}');                                    mybtn.click();                }    c. Apex Methods CreateContact and SaveUser are the pagereference methods which contains the code to create contact and user respectively.       After inserting the user inside the second apex method you can just set some public Properties in the page,        for ex:- created userid to get the user details and display in the page to show the acknowledgement to the users that the User is created.

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• No wireless connection using a conceptronic c54i (RT2561/RT61 rev B)

  - by jrosell

  Detected but not working. New install on ubuntu 11.10 using coneptronic C54Ri. As documentation says it uses Ralink drivers.... Any ideas why my wireless does not work? $ lspci -nn | grep -i 'ralink' 01:05.0 Network controller: Ralink corp. RT2561/RT61 rev B 802.11g ifconfig eth0 Link encap:Ethernet HWaddr 00:1e:90:e5:af:13 inet addr:192.168.0.197 Bcast:192.168.0.255 Mask:255.255.255.0 inet6 addr: fe80::21e:90ff:fee5:af13/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:28361 errors:0 dropped:0 overruns:0 frame:0 TX packets:16858 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:39812172 (39.8 MB) TX bytes:1633405 (1.6 MB) Interrupt:43 Base address:0xc000 lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:80 errors:0 dropped:0 overruns:0 frame:0 TX packets:80 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:6608 (6.6 KB) TX bytes:6608 (6.6 KB) iwconfig wlan0 wlan0 IEEE 802.11abg ESSIDff/any Mode:Managed Access Point: Not-Associated Tx-Power=0 dBm Retry long limit:7 RTS thrff Fragment thrff Power Managementff lsmod | grep rt rt61pci 27493 0 crc_itu_t 12627 1 rt61pci rt2x00pci 14202 1 rt61pci rt2x00lib 48114 2 rt61pci,rt2x00pci mac80211 272785 2 rt2x00pci,rt2x00lib cfg80211 172392 2 rt2x00lib,mac80211 eeprom_93cx6 12653 1 rt61pci parport_pc 32114 1 parport 40930 3 ppdev,parport_pc,lp lsmod | grep rt [ 2497.816989] phy0 -> rt2x00pci_regbusy_read: Error - Indirect register access failed: offset=0x0000308c, value=0xffffffff [ 2497.827112] phy0 -> rt2x00pci_regbusy_read: Error - Indirect register access failed: offset=0x0000308c, value=0xffffffff [ 2497.837430] phy0 -> rt2x00pci_regbusy_read: Error - Indirect register access failed: offset=0x0000308c, value=0xffffffff [ 2497.847528] phy0 -> rt2x00pci_regbusy_read: Error - Indirect register access failed: offset=0x0000308c, value=0xffffffff [ 2497.847632] phy0 -> rt61pci_wait_bbp_ready: Error - BBP register access faile d, aborting. [ 2497.847637] phy0 -> rt61pci_set_device_state: Error - Device failed to enter state 4 (-5). sudo lshw -C network *-network DISABLED description: Wireless interface product: RT2561/RT61 rev B 802.11g vendor: Ralink corp. physical id: 5 bus info: pci@0000:01:05.0 logical name: wlan0 version: 00 serial: fa:b8:14:58:62:35 width: 32 bits clock: 33MHz capabilities: pm cap_list ethernet physical wireless configuration: broadcast=yes driver=rt61pci driverversion=3.0.0-12-generic firmware=0.8 latency=0 link=no multicast=yes wireless=IEEE 802.11abg resources: irq:16 memory:fdef8000-fdefffff iwlist scan lo Interface doesn't support scanning. eth0 Interface doesn't support scanning. wlan0 Failed to read scan data : Network is down uname -mr 3.0.0-12-generic i686 Edit 1 $ rfkill list all 0: phy0: Wireless LAN Soft blocked: no Hard blocked: no On reboot, sudo lshw -C network returns network is ok. Hovever, WPA keeps on asking the wireless key

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• Styling Windows Phone Silverlight Applications

  - by Tim Murphy

  If you have not developed with styles in Silverlight/XAML then it can be challenging and resources can be sparse depending on how deep you get.  One thing that you need to understand is what level you can apply styles and how much they can cascade.  What I am finding is that this doesn’t go to the level that we are used to in HTML and CSS. While styles can be defined at a page level if you want to share styles throughout your application they should be defined in the App.xaml file.  This is of course analogous to placing a style in your HTML file versus an external CSS file.  This is the type of style I will concentrate on in this post. The first thing to look it how styles associate to elements.  TargetType defines the object type that your style will apply to.  In the example below the style is targeting the TextBlock object type. <Style x:Key="TextBlockSmallGray" TargetType="TextBlock"> Next we use a Setter which allows you to apply values for specific attributes of the target object type.  The setters can be a simple value or complex.  The first example here is simply applying a color to the background property of the target. <Setter Property="Background" Value="White"/> The second setter example here is for the same property, but we are applying a the definition of a LinearGradientBrush. <Setter Property="Background"> <Setter.Value> <LinearGradientBrush> <GradientStop Offset="0" Color="Black"/> <GradientStop Offset="1" Color="White"/> </LinearGradientBrush> </Setter.Value> </Setter> The last thing I want to cover here is that you can leverage the system styles and then override or extend them.  The BasedOn attribute of the Style tag allows this sort of inheritance.  In the example below I am going to start with the PhoneTextTitleStyle and then override properties as needed. <Style x:Key="TextBlockTitle" BasedOn="{StaticResource PhoneTextTitle1Style}" TargetType="TextBlock"> So now that we have our styles defined applying it is fairly straight forward.  Add the style name as a static resource to the style property of the element in your page and off you go. <Grid x:Name="LayoutRoot" Style="{StaticResource PageGridStyle}"> So this is one step in creating consistency in your application’s look.  In future posts I will dig a little deeper. del.icio.us Tags: windows phone 7,mobile development,windows phone 7 development,.NET,software development,design,UX

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