return on investment - Page 87

Which collection type should a reposity return results in? (.Net)

- by UpTheCreek

When using repository based persistence in a .net application, which collection type should normally be used? IList, IEnumerable? For example, the FindAll() method.

quiz ; does this compile and if so what does it return (I know the answer)

- by pm100

found this typo recently if (name.find('/' != string::npos)) I was amazed that it even compiles at -Wall -Werror (didnt try with -pedantic) so coffee quiz - does it eval to true or false

How do database servers decide which order to return rows without any "order by" statements?

Kind of a whimsical question, always something I've wondered about and I figure knowing why it does what it does might deepen my understanding a bit. Let's say I do "SELECT TOP 10 * FROM TableName". In short timeframes, the same 10 rows come back, so it doesn't seem random. They weren't the first or last created. In my massive sample size of...one table, it isn't returning the min or max auto-incrementing primary key value. I also figure the problem gets more complex when taking joins into account. My database of choice is MSSQL, but I figure this might be an interesting question regardless of the platform.

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does @@identity return the primary key or identity field?

- by elspiko

Hi, My issue is that I've got update triggers on an SQL View (MS SQL 2005) which I'm mapping to LINQ to SQL entities in C#... My SQL looks correct but it complains about trying to insert a null value into a secondary table PK field. I believe my issue relates to having the primary key and identity as seperate fields in the primary table. So my question is this....when using @@identity, does it look at the primary key of the inserted row, or does it look at the field with "IDENTITY" specified???

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Is it possible to submit data into a SQL database, wait for that to finish, and then return the ID g

- by user322478

I have an ASP form that needs to submit data to two different systems. First the data needs to go into an MS SQL database, which will get an ID. I then need to submit all that form data to an external system, along with that ID. Pretty much everything in the code works just fine, the data goes into the database, and the data will go to the external system. The problem is I am not getting my ID back from SQL when I execute that query. I am under the impression this is happening because of how fast everything occurs in the code. The database is adding it's row at the same time my post page runs it's query to get the ID back, I think. I need to know of a way to wait until SQL finished the insert or wait for a specific amount of time maybe. I already tried using the hacks to "sleep" with ASP, that did not help. I am sure I could accomplish this in .Net, my background is more .Net than ASP, but this is what I have to work with on my current project. Any ideas?

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Why does this Bash regex match return an Exit Status of "2"?

- by PreservedMoose

I'm writing a Bash script that needs to scan for the existence of non-ASCII characters in filenames. I'm using the POSIX bracket regex syntax to match the non-ASCII characters, but for some reason, when I test for the match in an if/then statement, the test always returns an Exit Status of 2, and never matches my test string. Here's the code in question: FILEREQ_SOURCEFILE="Filename–WithNonAScII-Charàcters-05sec_23.98.mov" REGEX_MATCH_NONASCII="[^[:ascii:]]" if [[ $FILEREQ_SOURCEFILE =~ $REGEX_MATCH_NONASCII ]]; then echo "Exit Status: $?" echo "Matched!" else echo "Exit Status: $?" echo "No Match" fi This code always returns: Exit Status: 2 No Match I've read and re-read the bash-hackers.org explanation of how regex matching works, as well as this previous question on SO regarding matching non-ASCII characters, but for the life of me, I can't get this to work. What am I missing here?

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ASP.NET MVC ‘Extendable-hooks’ – ControllerActionInvoker class

- by nmarun

There’s a class ControllerActionInvoker in ASP.NET MVC. This can be used as one of an hook-points to allow customization of your application. Watching Brad Wilsons’ Advanced MP3 from MVC Conf inspired me to write about this class. What MSDN says: “Represents a class that is responsible for invoking the action methods of a controller.” Well if MSDN says it, I think I can instill a fair amount of confidence into what the class does. But just to get to the details, I also looked into the source code for MVC. Seems like the base class Controller is where an IActionInvoker is initialized: 1: protected virtual IActionInvoker CreateActionInvoker() { 2: return new ControllerActionInvoker(); 3: } In the ControllerActionInvoker (the O-O-B behavior), there are different ‘versions’ of InvokeActionMethod() method that actually call the action method in question and return an instance of type ActionResult. 1: protected virtual ActionResult InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary<string, object> parameters) { 2: object returnValue = actionDescriptor.Execute(controllerContext, parameters); 3: ActionResult result = CreateActionResult(controllerContext, actionDescriptor, returnValue); 4: return result; 5: } I guess that’s enough on the ‘behind-the-screens’ of this class. Let’s see how we can use this class to hook-up extensions. Say I have a requirement that the user should be able to get different renderings of the same output, like html, xml, json, csv and so on. The user will type-in the output format in the url and should the get result accordingly. For example: http://site.com/RenderAs/ – renders the default way (the razor view) http://site.com/RenderAs/xml http://site.com/RenderAs/csv … and so on where RenderAs is my controller. There are many ways of doing this and I’m using a custom ControllerActionInvoker class (even though this might not be the best way to accomplish this). For this, my one and only route in the Global.asax.cs is: 1: routes.MapRoute("RenderAsRoute", "RenderAs/{outputType}", 2: new {controller = "RenderAs", action = "Index", outputType = ""}); Here the controller name is ‘RenderAsController’ and the action that’ll get called (always) is the Index action. The outputType parameter will map to the type of output requested by the user (xml, csv…). I intend to display a list of food items for this example. 1: public class Item 2: { 3: public int Id { get; set; } 4: public string Name { get; set; } 5: public Cuisine Cuisine { get; set; } 6: } 7: 8: public class Cuisine 9: { 10: public int CuisineId { get; set; } 11: public string Name { get; set; } 12: } Coming to my ‘RenderAsController’ class. I generate an IList<Item> to represent my model. 1: private static IList<Item> GetItems() 2: { 3: Cuisine cuisine = new Cuisine { CuisineId = 1, Name = "Italian" }; 4: Item item = new Item { Id = 1, Name = "Lasagna", Cuisine = cuisine }; 5: IList<Item> items = new List<Item> { item }; 6: item = new Item {Id = 2, Name = "Pasta", Cuisine = cuisine}; 7: items.Add(item); 8: //... 9: return items; 10: } My action method looks like 1: public IList<Item> Index(string outputType) 2: { 3: return GetItems(); 4: } There are two things that stand out in this action method. The first and the most obvious one being that the return type is not of type ActionResult (or one of its derivatives). Instead I’m passing the type of the model itself (IList<Item> in this case). We’ll convert this to some type of an ActionResult in our custom controller action invoker class later. The second thing (a little subtle) is that I’m not doing anything with the outputType value that is passed on to this action method. This value will be in the RouteData dictionary and we’ll use this in our custom invoker class as well. It’s time to hook up our invoker class. First, I’ll override the Initialize() method of my RenderAsController class. 1: protected override void Initialize(RequestContext requestContext) 2: { 3: base.Initialize(requestContext); 4: string outputType = string.Empty; 5: 6: // read the outputType from the RouteData dictionary 7: if (requestContext.RouteData.Values["outputType"] != null) 8: { 9: outputType = requestContext.RouteData.Values["outputType"].ToString(); 10: } 11: 12: // my custom invoker class 13: ActionInvoker = new ContentRendererActionInvoker(outputType); 14: } Coming to the main part of the discussion – the ContentRendererActionInvoker class: 1: public class ContentRendererActionInvoker : ControllerActionInvoker 2: { 3: private readonly string _outputType; 4: 5: public ContentRendererActionInvoker(string outputType) 6: { 7: _outputType = outputType.ToLower(); 8: } 9: //... 10: } So the outputType value that was read from the RouteData, which was passed in from the url, is being set here in a private field. Moving to the crux of this article, I now override the CreateActionResult method. 1: protected override ActionResult CreateActionResult(ControllerContext controllerContext, ActionDescriptor actionDescriptor, object actionReturnValue) 2: { 3: if (actionReturnValue == null) 4: return new EmptyResult(); 5: 6: ActionResult result = actionReturnValue as ActionResult; 7: if (result != null) 8: return result; 9: 10: // This is where the magic happens 11: // Depending on the value in the _outputType field, 12: // return an appropriate ActionResult 13: switch (_outputType) 14: { 15: case "json": 16: { 17: JavaScriptSerializer serializer = new JavaScriptSerializer(); 18: string json = serializer.Serialize(actionReturnValue); 19: return new ContentResult { Content = json, ContentType = "application/json" }; 20: } 21: case "xml": 22: { 23: XmlSerializer serializer = new XmlSerializer(actionReturnValue.GetType()); 24: using (StringWriter writer = new StringWriter()) 25: { 26: serializer.Serialize(writer, actionReturnValue); 27: return new ContentResult { Content = writer.ToString(), ContentType = "text/xml" }; 28: } 29: } 30: case "csv": 31: controllerContext.HttpContext.Response.AddHeader("Content-Disposition", "attachment; filename=items.csv"); 32: return new ContentResult 33: { 34: Content = ToCsv(actionReturnValue as IList<Item>), 35: ContentType = "application/ms-excel" 36: }; 37: case "pdf": 38: string filePath = controllerContext.HttpContext.Server.MapPath("~/items.pdf"); 39: controllerContext.HttpContext.Response.AddHeader("content-disposition", 40: "attachment; filename=items.pdf"); 41: ToPdf(actionReturnValue as IList<Item>, filePath); 42: return new FileContentResult(StreamFile(filePath), "application/pdf"); 43: 44: default: 45: controllerContext.Controller.ViewData.Model = actionReturnValue; 46: return new ViewResult 47: { 48: TempData = controllerContext.Controller.TempData, 49: ViewData = controllerContext.Controller.ViewData 50: }; 51: } 52: } A big method there! The hook I was talking about kinda above actually is here. This is where different kinds / formats of output get returned based on the output type requested in the url. When the _outputType is not set (string.Empty as set in the Global.asax.cs file), the razor view gets rendered (lines 45-50). This is the default behavior in most MVC applications where-in a view (webform/razor) gets rendered on the browser. As you see here, this gets returned as a ViewResult. But then, for an outputType of json/xml/csv, a ContentResult gets returned, while for pdf, a FileContentResult is returned. Here are how the different kinds of output look like: This is how we can leverage this feature of ASP.NET MVC to developer a better application. I’ve used the iTextSharp library to convert to a pdf format. Mike gives quite a bit of detail regarding this library here. You can download the sample code here. (You’ll get an option to download once you open the link). Verdict: Hot chocolate: $3; Reebok shoes: $50; Your first car: $3000; Being able to extend a web application: Priceless.

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Vertex buffer acting strange? [on hold]

- by Ryan Capote

I'm having a strange problem, and I don't know what could be causing it. My current code is identical to how I've done this before. I'm trying to render a rectangle using VBO and orthographic projection. My results: What I expect: 3x3 rectangle in the top left corner #include <stdio.h> #include <GL\glew.h> #include <GLFW\glfw3.h> #include "lodepng.h" static const int FALSE = 0; static const int TRUE = 1; static const char* VERT_SHADER = "#version 330\n" "layout(location=0) in vec4 VertexPosition; " "layout(location=1) in vec2 UV;" "uniform mat4 uProjectionMatrix;" /*"out vec2 TexCoords;"*/ "void main(void) {" " gl_Position = uProjectionMatrix*VertexPosition;" /*" TexCoords = UV;"*/ "}"; static const char* FRAG_SHADER = "#version 330\n" /*"uniform sampler2D uDiffuseTexture;" "uniform vec4 uColor;" "in vec2 TexCoords;"*/ "out vec4 FragColor;" "void main(void) {" /* " vec4 texel = texture2D(uDiffuseTexture, TexCoords);" " if(texel.a <= 0) {" " discard;" " }" " FragColor = texel;"*/ " FragColor = vec4(1.f);" "}"; static int g_running; static GLFWwindow *gl_window; static float gl_projectionMatrix[16]; /* Structures */ typedef struct _Vertex { float x, y, z, w; float u, v; } Vertex; typedef struct _Position { float x, y; } Position; typedef struct _Bitmap { unsigned char *pixels; unsigned int width, height; } Bitmap; typedef struct _Texture { GLuint id; unsigned int width, height; } Texture; typedef struct _VertexBuffer { GLuint bufferObj, vertexArray; } VertexBuffer; typedef struct _ShaderProgram { GLuint vertexShader, fragmentShader, program; } ShaderProgram; /* http://en.wikipedia.org/wiki/Orthographic_projection */ void createOrthoProjection(float *projection, float width, float height, float far, float near) { const float left = 0; const float right = width; const float top = 0; const float bottom = height; projection[0] = 2.f / (right - left); projection[1] = 0.f; projection[2] = 0.f; projection[3] = -(right+left) / (right-left); projection[4] = 0.f; projection[5] = 2.f / (top - bottom); projection[6] = 0.f; projection[7] = -(top + bottom) / (top - bottom); projection[8] = 0.f; projection[9] = 0.f; projection[10] = -2.f / (far-near); projection[11] = (far+near)/(far-near); projection[12] = 0.f; projection[13] = 0.f; projection[14] = 0.f; projection[15] = 1.f; } /* Textures */ void loadBitmap(const char *filename, Bitmap *bitmap, int *success) { int error = lodepng_decode32_file(&bitmap->pixels, &bitmap->width, &bitmap->height, filename); if (error != 0) { printf("Failed to load bitmap. "); printf(lodepng_error_text(error)); success = FALSE; return; } } void destroyBitmap(Bitmap *bitmap) { free(bitmap->pixels); } void createTexture(Texture *texture, const Bitmap *bitmap) { texture->id = 0; glGenTextures(1, &texture->id); glBindTexture(GL_TEXTURE_2D, texture); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bitmap->width, bitmap->height, 0, GL_RGBA, GL_UNSIGNED_BYTE, bitmap->pixels); glBindTexture(GL_TEXTURE_2D, 0); } void destroyTexture(Texture *texture) { glDeleteTextures(1, &texture->id); texture->id = 0; } /* Vertex Buffer */ void createVertexBuffer(VertexBuffer *vertexBuffer, Vertex *vertices) { glGenBuffers(1, &vertexBuffer->bufferObj); glGenVertexArrays(1, &vertexBuffer->vertexArray); glBindVertexArray(vertexBuffer->vertexArray); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj); glBufferData(GL_ARRAY_BUFFER, sizeof(Vertex) * 6, (const GLvoid*)vertices, GL_STATIC_DRAW); const unsigned int uvOffset = sizeof(float) * 4; glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, sizeof(Vertex), 0); glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)uvOffset); glEnableVertexAttribArray(0); glEnableVertexAttribArray(1); glBindBuffer(GL_ARRAY_BUFFER, 0); glBindVertexArray(0); } void destroyVertexBuffer(VertexBuffer *vertexBuffer) { glDeleteBuffers(1, &vertexBuffer->bufferObj); glDeleteVertexArrays(1, &vertexBuffer->vertexArray); } void bindVertexBuffer(VertexBuffer *vertexBuffer) { glBindVertexArray(vertexBuffer->vertexArray); glBindBuffer(GL_ARRAY_BUFFER, vertexBuffer->bufferObj); } void drawVertexBufferMode(GLenum mode) { glDrawArrays(mode, 0, 6); } void drawVertexBuffer() { drawVertexBufferMode(GL_TRIANGLES); } void unbindVertexBuffer() { glBindVertexArray(0); glBindBuffer(GL_ARRAY_BUFFER, 0); } /* Shaders */ void compileShader(ShaderProgram *shaderProgram, const char *vertexSrc, const char *fragSrc) { GLenum err; shaderProgram->vertexShader = glCreateShader(GL_VERTEX_SHADER); shaderProgram->fragmentShader = glCreateShader(GL_FRAGMENT_SHADER); if (shaderProgram->vertexShader == 0) { printf("Failed to create vertex shader."); return; } if (shaderProgram->fragmentShader == 0) { printf("Failed to create fragment shader."); return; } glShaderSource(shaderProgram->vertexShader, 1, &vertexSrc, NULL); glCompileShader(shaderProgram->vertexShader); glGetShaderiv(shaderProgram->vertexShader, GL_COMPILE_STATUS, &err); if (err != GL_TRUE) { printf("Failed to compile vertex shader."); return; } glShaderSource(shaderProgram->fragmentShader, 1, &fragSrc, NULL); glCompileShader(shaderProgram->fragmentShader); glGetShaderiv(shaderProgram->fragmentShader, GL_COMPILE_STATUS, &err); if (err != GL_TRUE) { printf("Failed to compile fragment shader."); return; } shaderProgram->program = glCreateProgram(); glAttachShader(shaderProgram->program, shaderProgram->vertexShader); glAttachShader(shaderProgram->program, shaderProgram->fragmentShader); glLinkProgram(shaderProgram->program); glGetProgramiv(shaderProgram->program, GL_LINK_STATUS, &err); if (err != GL_TRUE) { printf("Failed to link shader."); return; } } void destroyShader(ShaderProgram *shaderProgram) { glDetachShader(shaderProgram->program, shaderProgram->vertexShader); glDetachShader(shaderProgram->program, shaderProgram->fragmentShader); glDeleteShader(shaderProgram->vertexShader); glDeleteShader(shaderProgram->fragmentShader); glDeleteProgram(shaderProgram->program); } GLuint getUniformLocation(const char *name, ShaderProgram *program) { GLuint result = 0; result = glGetUniformLocation(program->program, name); return result; } void setUniformMatrix(float *matrix, const char *name, ShaderProgram *program) { GLuint loc = getUniformLocation(name, program); if (loc == -1) { printf("Failed to get uniform location in setUniformMatrix.\n"); return; } glUniformMatrix4fv(loc, 1, GL_FALSE, matrix); } /* General functions */ static int isRunning() { return g_running && !glfwWindowShouldClose(gl_window); } static void initializeGLFW(GLFWwindow **window, int width, int height, int *success) { if (!glfwInit()) { printf("Failed it inialize GLFW."); *success = FALSE; return; } glfwWindowHint(GLFW_RESIZABLE, 0); *window = glfwCreateWindow(width, height, "Alignments", NULL, NULL); if (!*window) { printf("Failed to create window."); glfwTerminate(); *success = FALSE; return; } glfwMakeContextCurrent(*window); GLenum glewErr = glewInit(); if (glewErr != GLEW_OK) { printf("Failed to initialize GLEW."); printf(glewGetErrorString(glewErr)); *success = FALSE; return; } glClearColor(0.f, 0.f, 0.f, 1.f); glViewport(0, 0, width, height); *success = TRUE; } int main(int argc, char **argv) { int err = FALSE; initializeGLFW(&gl_window, 480, 320, &err); glDisable(GL_DEPTH_TEST); if (err == FALSE) { return 1; } createOrthoProjection(gl_projectionMatrix, 480.f, 320.f, 0.f, 1.f); g_running = TRUE; ShaderProgram shader; compileShader(&shader, VERT_SHADER, FRAG_SHADER); glUseProgram(shader.program); setUniformMatrix(&gl_projectionMatrix, "uProjectionMatrix", &shader); Vertex rectangle[6]; VertexBuffer vbo; rectangle[0] = (Vertex){0.f, 0.f, 0.f, 1.f, 0.f, 0.f}; // Top left rectangle[1] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top right rectangle[2] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left rectangle[3] = (Vertex){3.f, 0.f, 0.f, 1.f, 1.f, 0.f}; // Top left rectangle[4] = (Vertex){0.f, 3.f, 0.f, 1.f, 0.f, 1.f}; // Bottom left rectangle[5] = (Vertex){3.f, 3.f, 0.f, 1.f, 1.f, 1.f}; // Bottom right createVertexBuffer(&vbo, &rectangle); bindVertexBuffer(&vbo); while (isRunning()) { glClear(GL_COLOR_BUFFER_BIT); glfwPollEvents(); drawVertexBuffer(); glfwSwapBuffers(gl_window); } unbindVertexBuffer(&vbo); glUseProgram(0); destroyShader(&shader); destroyVertexBuffer(&vbo); glfwTerminate(); return 0; }

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C# HashSet<T>

- by Ben Griswold

I hadn’t done much (read: anything) with the C# generic HashSet until I recently needed to produce a distinct collection. As it turns out, HashSet<T> was the perfect tool. As the following snippet demonstrates, this collection type offers a lot: // Using HashSet<T>: // http://www.albahari.com/nutshell/ch07.aspx var letters = new HashSet<char>("the quick brown fox"); Console.WriteLine(letters.Contains('t')); // true Console.WriteLine(letters.Contains('j')); // false foreach (char c in letters) Console.Write(c); // the quickbrownfx Console.WriteLine(); letters = new HashSet<char>("the quick brown fox"); letters.IntersectWith("aeiou"); foreach (char c in letters) Console.Write(c); // euio Console.WriteLine(); letters = new HashSet<char>("the quick brown fox"); letters.ExceptWith("aeiou"); foreach (char c in letters) Console.Write(c); // th qckbrwnfx Console.WriteLine(); letters = new HashSet<char>("the quick brown fox"); letters.SymmetricExceptWith("the lazy brown fox"); foreach (char c in letters) Console.Write(c); // quicklazy Console.WriteLine(); The MSDN documentation is a bit light on HashSet<T> documentation but if you search hard enough you can find some interesting information and benchmarks. But back to that distinct list I needed… // MSDN Add // http://msdn.microsoft.com/en-us/library/bb353005.aspx var employeeA = new Employee {Id = 1, Name = "Employee A"}; var employeeB = new Employee {Id = 2, Name = "Employee B"}; var employeeC = new Employee {Id = 3, Name = "Employee C"}; var employeeD = new Employee {Id = 4, Name = "Employee D"}; var naughty = new List<Employee> {employeeA}; var nice = new List<Employee> {employeeB, employeeC}; var employees = new HashSet<Employee>(); naughty.ForEach(x => employees.Add(x)); nice.ForEach(x => employees.Add(x)); foreach (Employee e in employees) Console.WriteLine(e); // Returns Employee A Employee B Employee C The Add Method returns true on success and, you guessed it, false if the item couldn’t be added to the collection. I’m using the Linq ForEach syntax to add all valid items to the employees HashSet. It works really great. This is just a rough sample, but you may have noticed I’m using Employee, a reference type. Most samples demonstrate the power of the HashSet with a collection of integers which is kind of cheating. With value types you don’t have to worry about defining your own equality members. With reference types, you do. internal class Employee { public int Id { get; set; } public string Name { get; set; } public override string ToString() { return Name; } public bool Equals(Employee other) { if (ReferenceEquals(null, other)) return false; if (ReferenceEquals(this, other)) return true; return other.Id == Id; } public override bool Equals(object obj) { if (ReferenceEquals(null, obj)) return false; if (ReferenceEquals(this, obj)) return true; if (obj.GetType() != typeof (Employee)) return false; return Equals((Employee) obj); } public override int GetHashCode() { return Id; } public static bool operator ==(Employee left, Employee right) { return Equals(left, right); } public static bool operator !=(Employee left, Employee right) { return !Equals(left, right); } } Fortunately, with Resharper, it’s a snap. Click on the class name, ALT+INS and then follow with the handy dialogues. That’s it. Try out the HashSet<T>. It’s good stuff.

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PeopleSoft Upgrades, Fusion, & BI for Leading European PeopleSoft Applications Customers

- by Mark Rosenberg

With so many industry-leading services firms around the globe managing their businesses with PeopleSoft, it’s always an adventure setting up times and meetings for us to keep in touch with them, especially those outside of North America who often do not get to join us at Oracle OpenWorld. Fortunately, during the first two weeks of May, Nigel Woodland (Oracle’s Service Industries Director for the EMEA region) and I successfully blocked off our calendars to visit seven different customers spanning four countries in Western Europe. We met executives and leaders at four Staffing industry firms, two Professional Services firms that engage in consulting and auditing, and a Financial Services firm. As we shared the latest information regarding product capabilities and plans, we also gained valuable insight into the hot technology topics facing these businesses. What we heard was both informative and inspiring, and I suspect other Oracle PeopleSoft applications customers can benefit from one or more of the following observations from our trip. Great IT Plans Get Executed When You Respect the Users Each of our visits followed roughly the same pattern. After introductions, Nigel outlined Oracle’s product and technology strategy, including a discussion of how we at Oracle invest in each layer of the “technology stack” to provide customers with unprecedented business management capabilities and choice. Then, I provided the specifics of the PeopleSoft product line’s investment strategy, detailing the dramatic number of rich usability and functionality enhancements added to release 9.1 since its general availability in 2009 and the game-changing capabilities slated for 9.2. What was most exciting about each of these discussions was that shortly after my talking about what customers can do with release 9.1 right now to drive up user productivity and satisfaction, I saw the wheels turning in the minds of our audiences. Business analyst and end user-configurable tools and technologies, such as WorkCenters and the Related Action Framework, that provide the ability to tailor a “central command center” to the exact needs of each recruiter, biller, and every other role in the organization were exactly what each of our customers had been looking for. Every one of our audiences agreed that these tools which demonstrate a respect for the user would finally help IT pole vault over the wall of resistance that users had often raised in the past. With these new user-focused capabilities, IT is positioned to definitively partner with the business, instead of drag the business along, to unlock the value of their investment in PeopleSoft. This topic of respecting the user emerged during our very first visit, which was at Vital Services Group at their Head Office “The Mill” in Manchester, England. (If you are a student of architecture and are ever in Manchester, you should stop in to see this amazingly renovated old mill building.) I had just finished explaining our PeopleSoft 9.2 roadmap, and Mike Code, PeopleSoft Systems Manager for this innovative staffing company, said, “Mark, the new features you’ve shown us in 9.1/9.2 are very relevant to our business. As we forge ahead with the 9.1 upgrade, the ability to configure a targeted user interface with WorkCenters, Related Actions, Pivot Grids, and Alerts will enable us to satisfy the business that this upgrade is for them and will deliver tangible benefits. In fact, you’ve highlighted that we need to start talking to the business to keep up the momentum to start reviewing the 9.2 upgrade after we get to 9.1, because as much as 9.1 and PeopleTools 8.52 offers, what you’ve shown us for 9.2 is what we’ve envisioned was ultimately possible with our investment in PeopleSoft applications.” We also received valuable feedback about our investment for the Staffing industry when we visited with Hans Wanders, CIO of Randstad (the second largest Staffing company in the world) in the Netherlands. After our visit, Hans noted, “It was very interesting to see how the PeopleSoft applications have developed. I was truly impressed by many of the new developments.” Hans and Mike, sincere thanks for the validation that our team’s hard work and dedication to “respecting the users” is worth the effort! Co-existence of PeopleSoft and Fusion Applications Just Makes Sense As a “product person,” one of the most rewarding things about visiting customers is that they actually want to talk to me. Sometimes, they want to discuss a product area that we need to enhance; other times, they are interested in learning how to extract more value from their applications; and still others, they want to tell me how they are using the applications to drive real value for the business. During this trip, I was very pleased to hear that several of our customers not only thought the co-existence of Fusion applications alongside PeopleSoft applications made sense in theory, but also that they were aggressively looking at how to deploy one or more Fusion applications alongside their PeopleSoft HCM and FSCM applications. The most common deployment plan in the works by three of the organizations is to upgrade to PeopleSoft 9.1 or 9.2, and then adopt one of the new Fusion HCM applications, such as Fusion Performance Management or the full suite of Fusion Talent Management. For example, during an applications upgrade planning discussion with the staffing company Hays plc., Mark Thomas, who is Hays’ UK IT Director, commented, “We are very excited about where we can go with the latest versions of the PeopleSoft applications in conjunction with Fusion Talent Management.” Needless to say, this news was very encouraging, because it reiterated that our applications investment strategy makes good business sense for our customers. Next Generation Business Intelligence Is the Key to the Future The third, and perhaps most exciting, lesson I learned during this journey is that our audiences already know that the latest generation of Business Intelligence technologies will be the “secret sauce” for organizations to transform business in radical ways. While a number of the organizations we visited on the trip have deployed or are deploying Oracle Business Intelligence Enterprise Edition and the associated analytics applications to provide dashboards of easy-to-understand, user-configurable metrics that help optimize business performance according to current operating procedures, what’s most exciting to them is being able to use Business Intelligence to change the way an organization does business, grows revenue, and makes a profit. In particular, several executives we met asked whether we can help them minimize the need to have perfectly structured data and at the same time generate analytics that improve order fulfillment decision-making. To them, the path to future growth lies in having the ability to analyze unstructured data rapidly and intuitively and leveraging technology’s ability to detect patterns that a human cannot reasonably be expected to see. For illustrative purposes, here is a good example of a business problem where analyzing a combination of structured and unstructured data can produce better results. If you have a resource manager trying to decide which person would be the best fit for an assignment in terms of ensuring (a) client satisfaction, (b) the individual’s satisfaction with the work, (c) least travel distance, and (d) highest margin, you traditionally compare resource qualifications to assignment needs, calculate margins on past work with the client, and measure distances. To perform these comparisons, you are likely to need the organization to have profiles setup, people ranked against profiles, margin targets setup, margins measured, distances setup, distances measured, and more. As you can imagine, this requires organizations to plan and implement data setup, capture, and quality management initiatives to ensure that dependable information is available to support resourcing analysis and decisions. In the fast-paced, tight-budget world in which most organizations operate today, the effort and discipline required to maintain high-quality, structured data like those described in the above example are certainly not desirable and in some cases are not feasible. You can imagine how intrigued our audiences were when I informed them that we are ready to help them analyze volumes of unstructured data, detect trends, and produce recommendations. Our discussions delved into examples of how the firms could leverage Oracle’s Secure Enterprise Search and Endeca technologies to keyword search against, compare, and learn from unstructured resource and assignment data. We also considered examples of how they could employ Oracle Real-Time Decisions to generate statistically significant recommendations based on similar resourcing scenarios that have produced the desired satisfaction and profit margin results. --- Although I had almost no time for sight-seeing during this trip to Europe, I have to say that it may have been one of the most energizing and engaging trips of my career. Showing these dedicated customers how they can give every user a uniquely tailored set of tools and address business problems in ways that have to date been impossible made the journey across the Atlantic more than worth it. If any of these three topics intrigue you, I’d recommend you contact your Oracle applications representative to arrange for more detailed discussions with the appropriate members of our organization.

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Unable to sign in. How to debug?

- by Dmitriy Budnik

I had to reboot system with reset button. After reboot I can't sign in. When I enter my password It seems like X-server just restarts. I can sing in as guest and also I can sign in in text TTY. Here is first 150 lines of my lightdm.log: [+0.04s] DEBUG: Logging to /var/log/lightdm/lightdm.log [+0.04s] DEBUG: Starting Light Display Manager 1.2.1, UID=0 PID=1070 [+0.04s] DEBUG: Loaded configuration from /etc/lightdm/lightdm.conf [+0.04s] DEBUG: Using D-Bus name org.freedesktop.DisplayManager [+0.04s] DEBUG: Registered seat module xlocal [+0.04s] DEBUG: Registered seat module xremote [+0.04s] DEBUG: Adding default seat [+0.04s] DEBUG: Starting seat [+0.04s] DEBUG: Starting new display for automatic login as user dmytro [+0.04s] DEBUG: Starting local X display [+3.64s] DEBUG: X server :0 will replace Plymouth [+3.66s] DEBUG: Using VT 7 [+3.66s] DEBUG: Activating VT 7 [+3.66s] DEBUG: Logging to /var/log/lightdm/x-0.log [+3.66s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0 [+3.66s] DEBUG: Launching X Server [+3.66s] DEBUG: Launching process 1154: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch -background none [+3.66s] DEBUG: Waiting for ready signal from X server :0 [+3.66s] DEBUG: Acquired bus name org.freedesktop.DisplayManager [+3.66s] DEBUG: Registering seat with bus path /org/freedesktop/DisplayManager/Seat0 [+10.78s] DEBUG: Got signal 10 from process 1154 [+10.78s] DEBUG: Got signal from X server :0 [+10.78s] DEBUG: Stopping Plymouth, X server is ready [+10.80s] DEBUG: Connecting to XServer :0 [+10.80s] DEBUG: Automatically logging in user dmytro [+10.80s] DEBUG: Started session 1303 with service 'lightdm-autologin', username 'dmytro' [+13.22s] DEBUG: Session 1303 authentication complete with return value 0: Success [+13.26s] DEBUG: Autologin user dmytro authorized [+13.27s] DEBUG: Autologin using session ubuntu [+14.44s] DEBUG: Dropping privileges to uid 1000 [+14.48s] DEBUG: Restoring privileges [+14.49s] DEBUG: Dropping privileges to uid 1000 [+14.49s] DEBUG: Writing /home/dmytro/.dmrc [+14.61s] DEBUG: Restoring privileges [+14.81s] DEBUG: Starting session ubuntu as user dmytro [+14.81s] DEBUG: Session 1303 running command /usr/sbin/lightdm-session gnome-session --session=ubuntu [+15.76s] DEBUG: New display ready, switching to it [+15.76s] DEBUG: Activating VT 7 [+15.76s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session0 [+16.63s] DEBUG: Session 1303 exited with return value 0 [+16.63s] DEBUG: User session quit [+16.63s] DEBUG: Stopping display [+16.63s] DEBUG: Sending signal 15 to process 1154 [+17.19s] DEBUG: Process 1154 exited with return value 0 [+17.19s] DEBUG: X server stopped [+17.19s] DEBUG: Removing X server authority /var/run/lightdm/root/:0 [+17.19s] DEBUG: Releasing VT 7 [+17.19s] DEBUG: Display server stopped [+17.19s] DEBUG: Display stopped [+17.19s] DEBUG: Active display stopped, switching to greeter [+17.19s] DEBUG: Switching to greeter [+17.19s] DEBUG: Starting new display for greeter [+17.19s] DEBUG: Starting local X display [+17.19s] DEBUG: Using VT 7 [+17.19s] DEBUG: Logging to /var/log/lightdm/x-0.log [+17.19s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0 [+17.19s] DEBUG: Launching X Server [+17.19s] DEBUG: Launching process 1563: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch [+17.19s] DEBUG: Waiting for ready signal from X server :0 [+17.48s] DEBUG: Got signal 10 from process 1563 [+17.48s] DEBUG: Got signal from X server :0 [+17.48s] DEBUG: Connecting to XServer :0 [+17.48s] DEBUG: Starting greeter [+17.48s] DEBUG: Started session 1575 with service 'lightdm', username 'lightdm' [+17.61s] DEBUG: Session 1575 authentication complete with return value 0: Success [+17.61s] DEBUG: Greeter authorized [+17.61s] DEBUG: Logging to /var/log/lightdm/x-0-greeter.log [+17.68s] DEBUG: Session 1575 running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter [+20.86s] DEBUG: Greeter connected version=1.2.1 [+20.86s] DEBUG: Greeter connected, display is ready [+20.86s] DEBUG: New display ready, switching to it [+20.86s] DEBUG: Activating VT 7 [+20.86s] DEBUG: Stopping greeter display being switched from [+24.90s] DEBUG: Greeter start authentication for dmytro [+24.90s] DEBUG: Started session 1746 with service 'lightdm', username 'dmytro' [+25.10s] DEBUG: Session 1746 got 1 message(s) from PAM [+25.10s] DEBUG: Prompt greeter with 1 message(s) [+31.87s] DEBUG: Continue authentication [+33.75s] DEBUG: Session 1746 authentication complete with return value 7: Authentication failure [+33.75s] DEBUG: Authenticate result for user dmytro: Authentication failure [+33.75s] DEBUG: Greeter start authentication for dmytro [+33.75s] DEBUG: Session 1746: Sending SIGTERM [+33.75s] DEBUG: Started session 2264 with service 'lightdm', username 'dmytro' [+33.75s] DEBUG: Session 2264 got 1 message(s) from PAM [+33.75s] DEBUG: Prompt greeter with 1 message(s) [+36.41s] DEBUG: Continue authentication [+36.53s] DEBUG: Session 2264 authentication complete with return value 0: Success [+36.53s] DEBUG: Authenticate result for user dmytro: Success [+36.54s] DEBUG: User dmytro authorized [+36.54s] DEBUG: Greeter requests session ubuntu [+36.54s] DEBUG: Using session ubuntu [+36.54s] DEBUG: Stopping greeter [+36.54s] DEBUG: Session 1575: Sending SIGTERM [+37.41s] DEBUG: Greeter closed communication channel [+37.41s] DEBUG: Session 1575 exited with return value 0 [+37.41s] DEBUG: Greeter quit [+37.42s] DEBUG: Dropping privileges to uid 1000 [+37.42s] DEBUG: Restoring privileges [+37.43s] DEBUG: Dropping privileges to uid 1000 [+37.43s] DEBUG: Writing /home/dmytro/.dmrc [+38.35s] DEBUG: Restoring privileges [+40.37s] DEBUG: Starting session ubuntu as user dmytro [+40.37s] DEBUG: Session 2264 running command /usr/sbin/lightdm-session gnome-session --session=ubuntu [+40.39s] DEBUG: Registering session with bus path /org/freedesktop/DisplayManager/Session1 [+50.78s] DEBUG: Session 2264 exited with return value 0 [+50.78s] DEBUG: User session quit [+50.78s] DEBUG: Stopping display [+50.78s] DEBUG: Sending signal 15 to process 1563 [+51.53s] DEBUG: Process 1563 exited with return value 0 [+51.53s] DEBUG: X server stopped [+51.53s] DEBUG: Removing X server authority /var/run/lightdm/root/:0 [+51.53s] DEBUG: Releasing VT 7 [+51.53s] DEBUG: Display server stopped [+51.53s] DEBUG: Display stopped [+51.53s] DEBUG: Active display stopped, switching to greeter [+51.53s] DEBUG: Switching to greeter [+51.53s] DEBUG: Starting new display for greeter [+51.53s] DEBUG: Starting local X display [+51.53s] DEBUG: Using VT 7 [+51.53s] DEBUG: Logging to /var/log/lightdm/x-0.log [+51.53s] DEBUG: Writing X server authority to /var/run/lightdm/root/:0 [+51.53s] DEBUG: Launching X Server [+51.53s] DEBUG: Launching process 2894: /usr/bin/X :0 -auth /var/run/lightdm/root/:0 -nolisten tcp vt7 -novtswitch [+51.53s] DEBUG: Waiting for ready signal from X server :0 [+51.75s] DEBUG: Got signal 10 from process 2894 [+51.75s] DEBUG: Got signal from X server :0 [+51.75s] DEBUG: Connecting to XServer :0 [+51.75s] DEBUG: Starting greeter [+51.75s] DEBUG: Started session 2898 with service 'lightdm', username 'lightdm' [+51.76s] DEBUG: Session 2898 authentication complete with return value 0: Success [+51.76s] DEBUG: Greeter authorized [+51.76s] DEBUG: Logging to /var/log/lightdm/x-0-greeter.log [+51.76s] DEBUG: Session 2898 running command /usr/lib/lightdm/lightdm-greeter-session /usr/sbin/unity-greeter [+53.26s] DEBUG: Greeter connected version=1.2.1 [+53.26s] DEBUG: Greeter connected, display is ready [+53.26s] DEBUG: New display ready, switching to it [+53.26s] DEBUG: Activating VT 7 [+53.26s] DEBUG: Stopping greeter display being switched from [+54.17s] DEBUG: Greeter start authentication for dmytro [+54.17s] DEBUG: Started session 3152 with service 'lightdm', username 'dmytro' [+54.18s] DEBUG: Session 3152 got 1 message(s) from PAM [+54.18s] DEBUG: Prompt greeter with 1 message(s) [+58.61s] DEBUG: Continue authentication [+58.65s] DEBUG: Session 3152 authentication complete with return value 0: Success [+58.65s] DEBUG: Authenticate result for user dmytro: Success [+58.66s] DEBUG: User dmytro authorized [+58.66s] DEBUG: Greeter requests session ubuntu [+58.66s] DEBUG: Using session ubuntu [+58.66s] DEBUG: Stopping greeter [+58.66s] DEBUG: Session 2898: Sending SIGTERM How can I fix it? What other .log files could possibly give me a clue? Update: Possibly it's duplicate of Desktop login fails, terminal works

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Blackberry Player, custom data source

- by Alex

Hello I must create a custom media player within the application with support for mp3 and wav files. I read in the documentation i cant seek or get the media file duration without a custom datasoruce. I checked the demo in the JDE 4.6 but i have still problems... I cant get the duration, it return much more then the expected so i`m sure i screwed up something while i modified the code to read the mp3 file locally from the filesystem. Somebody can help me what i did wrong ? (I can hear the mp3, so the player plays it correctly from start to end) I must support OSs = 4.6. Thank You Here is my modified datasource LimitedRateStreaminSource.java * Copyright © 1998-2009 Research In Motion Ltd. Note: For the sake of simplicity, this sample application may not leverage resource bundles and resource strings. However, it is STRONGLY recommended that application developers make use of the localization features available within the BlackBerry development platform to ensure a seamless application experience across a variety of languages and geographies. For more information on localizing your application, please refer to the BlackBerry Java Development Environment Development Guide associated with this release. */ package com.halcyon.tawkwidget.model; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import javax.microedition.io.Connector; import javax.microedition.io.file.FileConnection; import javax.microedition.media.Control; import javax.microedition.media.protocol.ContentDescriptor; import javax.microedition.media.protocol.DataSource; import javax.microedition.media.protocol.SourceStream; import net.rim.device.api.io.SharedInputStream; /** * The data source used by the BufferedPlayback's media player. / public final class LimitedRateStreamingSource extends DataSource { /* The max size to be read from the stream at one time. */ private static final int READ_CHUNK = 512; // bytes /** A reference to the field which displays the load status. */ //private TextField _loadStatusField; /** A reference to the field which displays the player status. */ //private TextField _playStatusField; /** * The minimum number of bytes that must be buffered before the media file * will begin playing. */ private int _startBuffer = 200000; /** The maximum size (in bytes) of a single read. */ private int _readLimit = 32000; /** * The minimum forward byte buffer which must be maintained in order for * the video to keep playing. If the forward buffer falls below this * number, the playback will pause until the buffer increases. */ private int _pauseBytes = 64000; /** * The minimum forward byte buffer required to resume * playback after a pause. */ private int _resumeBytes = 128000; /** The stream connection over which media content is passed. */ //private ContentConnection _contentConnection; private FileConnection _fileConnection; /** An input stream shared between several readers. */ private SharedInputStream _readAhead; /** A stream to the buffered resource. */ private LimitedRateSourceStream _feedToPlayer; /** The MIME type of the remote media file. */ private String _forcedContentType; /** A counter for the total number of buffered bytes */ private volatile int _totalRead; /** A flag used to tell the connection thread to stop */ private volatile boolean _stop; /** * A flag used to indicate that the initial buffering is complete. In * other words, that the current buffer is larger than the defined start * buffer size. */ private volatile boolean _bufferingComplete; /** A flag used to indicate that the remote file download is complete. */ private volatile boolean _downloadComplete; /** The thread which retrieves the remote media file. */ private ConnectionThread _loaderThread; /** The local save file into which the remote file is written. */ private FileConnection _saveFile; /** A stream for the local save file. */ private OutputStream _saveStream; /** * Constructor. * @param locator The locator that describes the DataSource. */ public LimitedRateStreamingSource(String locator) { super(locator); } /** * Open a connection to the locator. * @throws IOException */ public void connect() throws IOException { //Open the connection to the remote file. _fileConnection = (FileConnection)Connector.open(getLocator(), Connector.READ); //Cache a reference to the locator. String locator = getLocator(); //Report status. System.out.println("Loading: " + locator); //System.out.println("Size: " + _contentConnection.getLength()); System.out.println("Size: " + _fileConnection.totalSize()); //The name of the remote file begins after the last forward slash. int filenameStart = locator.lastIndexOf('/'); //The file name ends at the first instance of a semicolon. int paramStart = locator.indexOf(';'); //If there is no semicolon, the file name ends at the end of the line. if (paramStart < 0) { paramStart = locator.length(); } //Extract the file name. String filename = locator.substring(filenameStart, paramStart); System.out.println("Filename: " + filename); //Open a local save file with the same name as the remote file. _saveFile = (FileConnection) Connector.open("file:///SDCard/blackberry/music" + filename, Connector.READ_WRITE); //If the file doesn't already exist, create it. if (!_saveFile.exists()) { _saveFile.create(); } System.out.println("---------- 1"); //Open the file for writing. _saveFile.setReadable(true); //Open a shared input stream to the local save file to //allow many simultaneous readers. SharedInputStream fileStream = SharedInputStream.getSharedInputStream(_saveFile.openInputStream()); //Begin reading at the beginning of the file. fileStream.setCurrentPosition(0); System.out.println("---------- 2"); //If the local file is smaller than the remote file... if (_saveFile.fileSize() < _fileConnection.totalSize()) { System.out.println("---------- 3"); //Did not get the entire file, set the system to try again. _saveFile.setWritable(true); System.out.println("---------- 4"); //A non-null save stream is used as a flag later to indicate that //the file download was incomplete. _saveStream = _saveFile.openOutputStream(); System.out.println("---------- 5"); //Use a new shared input stream for buffered reading. _readAhead = SharedInputStream.getSharedInputStream(_fileConnection.openInputStream()); System.out.println("---------- 6"); } else { //The download is complete. System.out.println("---------- 7"); _downloadComplete = true; //We can use the initial input stream to read the buffered media. _readAhead = fileStream; System.out.println("---------- 8"); //We can close the remote connection. _fileConnection.close(); System.out.println("---------- 9"); } if (_forcedContentType != null) { //Use the user-defined content type if it is set. System.out.println("---------- 10"); _feedToPlayer = new LimitedRateSourceStream(_readAhead, _forcedContentType); System.out.println("---------- 11"); } else { System.out.println("---------- 12"); //Otherwise, use the MIME types of the remote file. // _feedToPlayer = new LimitedRateSourceStream(_readAhead, _fileConnection)); } System.out.println("---------- 13"); } /** * Destroy and close all existing connections. */ public void disconnect() { try { if (_saveStream != null) { //Destroy the stream to the local save file. _saveStream.close(); _saveStream = null; } //Close the local save file. _saveFile.close(); if (_readAhead != null) { //Close the reader stream. _readAhead.close(); _readAhead = null; } //Close the remote file connection. _fileConnection.close(); //Close the stream to the player. _feedToPlayer.close(); } catch (Exception e) { System.err.println(e.getMessage()); } } /** * Returns the content type of the remote file. * @return The content type of the remote file. */ public String getContentType() { return _feedToPlayer.getContentDescriptor().getContentType(); } /** * Returns a stream to the buffered resource. * @return A stream to the buffered resource. */ public SourceStream[] getStreams() { return new SourceStream[] { _feedToPlayer }; } /** * Starts the connection thread used to download the remote file. */ public void start() throws IOException { //If the save stream is null, we have already completely downloaded //the file. if (_saveStream != null) { //Open the connection thread to finish downloading the file. _loaderThread = new ConnectionThread(); _loaderThread.start(); } } /** * Stop the connection thread. */ public void stop() throws IOException { //Set the boolean flag to stop the thread. _stop = true; } /** * @see javax.microedition.media.Controllable#getControl(String) */ public Control getControl(String controlType) { // No implemented Controls. return null; } /** * @see javax.microedition.media.Controllable#getControls() */ public Control[] getControls() { // No implemented Controls. return null; } /** * Force the lower level stream to a given content type. Must be called * before the connect function in order to work. * @param contentType The content type to use. */ public void setContentType(String contentType) { _forcedContentType = contentType; } /** * A stream to the buffered media resource. */ private final class LimitedRateSourceStream implements SourceStream { /** A stream to the local copy of the remote resource. */ private SharedInputStream _baseSharedStream; /** Describes the content type of the media file. */ private ContentDescriptor _contentDescriptor; /** * Constructor. Creates a LimitedRateSourceStream from * the given InputStream. * @param inputStream The input stream used to create a new reader. * @param contentType The content type of the remote file. */ LimitedRateSourceStream(InputStream inputStream, String contentType) { System.out.println("[LimitedRateSoruceStream]---------- 1"); _baseSharedStream = SharedInputStream.getSharedInputStream(inputStream); System.out.println("[LimitedRateSoruceStream]---------- 2"); _contentDescriptor = new ContentDescriptor(contentType); System.out.println("[LimitedRateSoruceStream]---------- 3"); } /** * Returns the content descriptor for this stream. * @return The content descriptor for this stream. */ public ContentDescriptor getContentDescriptor() { return _contentDescriptor; } /** * Returns the length provided by the connection. * @return long The length provided by the connection. */ public long getContentLength() { return _fileConnection.totalSize(); } /** * Returns the seek type of the stream. */ public int getSeekType() { return RANDOM_ACCESSIBLE; //return SEEKABLE_TO_START; } /** * Returns the maximum size (in bytes) of a single read. */ public int getTransferSize() { return _readLimit; } /** * Writes bytes from the buffer into a byte array for playback. * @param bytes The buffer into which the data is read. * @param off The start offset in array b at which the data is written. * @param len The maximum number of bytes to read. * @return the total number of bytes read into the buffer, or -1 if * there is no more data because the end of the stream has been reached. * @throws IOException */ public int read(byte[] bytes, int off, int len) throws IOException { System.out.println("[LimitedRateSoruceStream]---------- 5"); System.out.println("Read Request for: " + len + " bytes"); //Limit bytes read to our readLimit. int readLength = len; System.out.println("[LimitedRateSoruceStream]---------- 6"); if (readLength > getReadLimit()) { readLength = getReadLimit(); } //The number of available byes in the buffer. int available; //A boolean flag indicating that the thread should pause //until the buffer has increased sufficiently. boolean paused = false; System.out.println("[LimitedRateSoruceStream]---------- 7"); for (;;) { available = _baseSharedStream.available(); System.out.println("[LimitedRateSoruceStream]---------- 8"); if (_downloadComplete) { //Ignore all restrictions if downloading is complete. System.out.println("Complete, Reading: " + len + " - Available: " + available); return _baseSharedStream.read(bytes, off, len); } else if(_bufferingComplete) { if (paused && available > getResumeBytes()) { //If the video is paused due to buffering, but the //number of available byes is sufficiently high, //resume playback of the media. System.out.println("Resuming - Available: " + available); paused = false; return _baseSharedStream.read(bytes, off, readLength); } else if(!paused && (available > getPauseBytes() || available > readLength)) { //We have enough information for this media playback. if (available < getPauseBytes()) { //If the buffer is now insufficient, set the //pause flag. paused = true; } System.out.println("Reading: " + readLength + " - Available: " + available); return _baseSharedStream.read(bytes, off, readLength); } else if(!paused) { //Set pause until loaded enough to resume. paused = true; } } else { //We are not ready to start yet, try sleeping to allow the //buffer to increase. try { Thread.sleep(500); } catch (Exception e) { System.err.println(e.getMessage()); } } } } /** * @see javax.microedition.media.protocol.SourceStream#seek(long) */ public long seek(long where) throws IOException { _baseSharedStream.setCurrentPosition((int) where); return _baseSharedStream.getCurrentPosition(); } /** * @see javax.microedition.media.protocol.SourceStream#tell() */ public long tell() { return _baseSharedStream.getCurrentPosition(); } /** * Close the stream. * @throws IOException */ void close() throws IOException { _baseSharedStream.close(); } /** * @see javax.microedition.media.Controllable#getControl(String) */ public Control getControl(String controlType) { // No implemented controls. return null; } /** * @see javax.microedition.media.Controllable#getControls() */ public Control[] getControls() { // No implemented controls. return null; } } /** * A thread which downloads the remote file and writes it to the local file. */ private final class ConnectionThread extends Thread { /** * Download the remote media file, then write it to the local * file. * @see java.lang.Thread#run() */ public void run() { try { byte[] data = new byte[READ_CHUNK]; int len = 0; //Until we reach the end of the file. while (-1 != (len = _readAhead.read(data))) { _totalRead += len; if (!_bufferingComplete && _totalRead > getStartBuffer()) { //We have enough of a buffer to begin playback. _bufferingComplete = true; System.out.println("Initial Buffering Complete"); } if (_stop) { //Stop reading. return; } } System.out.println("Downloading Complete"); System.out.println("Total Read: " + _totalRead); //If the downloaded data is not the same size //as the remote file, something is wrong. if (_totalRead != _fileConnection.totalSize()) { System.err.println("* Unable to Download entire file *"); } _downloadComplete = true; _readAhead.setCurrentPosition(0); //Write downloaded data to the local file. while (-1 != (len = _readAhead.read(data))) { _saveStream.write(data); } } catch (Exception e) { System.err.println(e.toString()); } } } /** * Gets the minimum forward byte buffer which must be maintained in * order for the video to keep playing. * @return The pause byte buffer. */ int getPauseBytes() { return _pauseBytes; } /** * Sets the minimum forward buffer which must be maintained in order * for the video to keep playing. * @param pauseBytes The new pause byte buffer. */ void setPauseBytes(int pauseBytes) { _pauseBytes = pauseBytes; } /** * Gets the maximum size (in bytes) of a single read. * @return The maximum size (in bytes) of a single read. */ int getReadLimit() { return _readLimit; } /** * Sets the maximum size (in bytes) of a single read. * @param readLimit The new maximum size (in bytes) of a single read. */ void setReadLimit(int readLimit) { _readLimit = readLimit; } /** * Gets the minimum forward byte buffer required to resume * playback after a pause. * @return The resume byte buffer. */ int getResumeBytes() { return _resumeBytes; } /** * Sets the minimum forward byte buffer required to resume * playback after a pause. * @param resumeBytes The new resume byte buffer. */ void setResumeBytes(int resumeBytes) { _resumeBytes = resumeBytes; } /** * Gets the minimum number of bytes that must be buffered before the * media file will begin playing. * @return The start byte buffer. */ int getStartBuffer() { return _startBuffer; } /** * Sets the minimum number of bytes that must be buffered before the * media file will begin playing. * @param startBuffer The new start byte buffer. */ void setStartBuffer(int startBuffer) { _startBuffer = startBuffer; } } And in this way i use it: LimitedRateStreamingSource source = new LimitedRateStreamingSource("file:///SDCard/music3.mp3"); source.setContentType("audio/mpeg"); mediaPlayer = javax.microedition.media.Manager.createPlayer(source); mediaPlayer.addPlayerListener(this); mediaPlayer.realize(); mediaPlayer.prefetch(); After start i use mediaPlayer.getDuration it returns lets say around 24:22 (the inbuild media player in the blackberry say the file length is 4:05) I tried to get the duration in the listener and there unfortunatly returned around 64 minutes, so im sure something is not good inside the datasoruce....

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WCF Bidirectional serialization fails

- by Gena Verdel

I'm trying to take advantage of Bidirectional serialization of some relational Linq-2-Sql generated entity classes. When using Unidirectional option everything works just fine, bu the moment I add IsReferenceType=true, objects fail to get transported over the tcp binding. Sample code: Entity class: [Table(Name="dbo.Blocks")] [DataContract()] public partial class Block : INotifyPropertyChanging, INotifyPropertyChanged { private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty); private long _ID; private int _StatusID; private string _Name; private bool _IsWithControlPoints; private long _DivisionID; private string _SHAPE; private EntitySet<BlockByWorkstation> _BlockByWorkstations; private EntitySet<PlanningPointAppropriation> _PlanningPointAppropriations; private EntitySet<Neighbor> _Neighbors; private EntitySet<Neighbor> _Neighbors1; private EntitySet<Task> _Tasks; private EntitySet<PlanningPointByBlock> _PlanningPointByBlocks; private EntitySet<ControlPointByBlock> _ControlPointByBlocks; private EntityRef<Division> _Division; private bool serializing; #region Extensibility Method Definitions partial void OnLoaded(); partial void OnValidate(System.Data.Linq.ChangeAction action); partial void OnCreated(); partial void OnIDChanging(long value); partial void OnIDChanged(); partial void OnStatusIDChanging(int value); partial void OnStatusIDChanged(); partial void OnNameChanging(string value); partial void OnNameChanged(); partial void OnIsWithControlPointsChanging(bool value); partial void OnIsWithControlPointsChanged(); partial void OnDivisionIDChanging(long value); partial void OnDivisionIDChanged(); partial void OnSHAPEChanging(string value); partial void OnSHAPEChanged(); #endregion public Block() { this.Initialize(); } [Column(Storage="_ID", AutoSync=AutoSync.OnInsert, DbType="BigInt NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)] [DataMember(Order=1)] public override long ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } [Column(Storage="_StatusID", DbType="Int NOT NULL")] [DataMember(Order=2)] public int StatusID { get { return this._StatusID; } set { if ((this._StatusID != value)) { this.OnStatusIDChanging(value); this.SendPropertyChanging(); this._StatusID = value; this.SendPropertyChanged("StatusID"); this.OnStatusIDChanged(); } } } [Column(Storage="_Name", DbType="NVarChar(255)")] [DataMember(Order=3)] public string Name { get { return this._Name; } set { if ((this._Name != value)) { this.OnNameChanging(value); this.SendPropertyChanging(); this._Name = value; this.SendPropertyChanged("Name"); this.OnNameChanged(); } } } [Column(Storage="_IsWithControlPoints", DbType="Bit NOT NULL")] [DataMember(Order=4)] public bool IsWithControlPoints { get { return this._IsWithControlPoints; } set { if ((this._IsWithControlPoints != value)) { this.OnIsWithControlPointsChanging(value); this.SendPropertyChanging(); this._IsWithControlPoints = value; this.SendPropertyChanged("IsWithControlPoints"); this.OnIsWithControlPointsChanged(); } } } [Column(Storage="_DivisionID", DbType="BigInt NOT NULL")] [DataMember(Order=5)] public long DivisionID { get { return this._DivisionID; } set { if ((this._DivisionID != value)) { if (this._Division.HasLoadedOrAssignedValue) { throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException(); } this.OnDivisionIDChanging(value); this.SendPropertyChanging(); this._DivisionID = value; this.SendPropertyChanged("DivisionID"); this.OnDivisionIDChanged(); } } } [Column(Storage="_SHAPE", DbType="Text", UpdateCheck=UpdateCheck.Never)] [DataMember(Order=6)] public string SHAPE { get { return this._SHAPE; } set { if ((this._SHAPE != value)) { this.OnSHAPEChanging(value); this.SendPropertyChanging(); this._SHAPE = value; this.SendPropertyChanged("SHAPE"); this.OnSHAPEChanged(); } } } [Association(Name="Block_BlockByWorkstation", Storage="_BlockByWorkstations", ThisKey="ID", OtherKey="BlockID")] [DataMember(Order=7, EmitDefaultValue=false)] public EntitySet<BlockByWorkstation> BlockByWorkstations { get { if ((this.serializing && (this._BlockByWorkstations.HasLoadedOrAssignedValues == false))) { return null; } return this._BlockByWorkstations; } set { this._BlockByWorkstations.Assign(value); } } [Association(Name="Block_PlanningPointAppropriation", Storage="_PlanningPointAppropriations", ThisKey="ID", OtherKey="MasterBlockID")] [DataMember(Order=8, EmitDefaultValue=false)] public EntitySet<PlanningPointAppropriation> PlanningPointAppropriations { get { if ((this.serializing && (this._PlanningPointAppropriations.HasLoadedOrAssignedValues == false))) { return null; } return this._PlanningPointAppropriations; } set { this._PlanningPointAppropriations.Assign(value); } } [Association(Name="Block_Neighbor", Storage="_Neighbors", ThisKey="ID", OtherKey="FirstBlockID")] [DataMember(Order=9, EmitDefaultValue=false)] public EntitySet<Neighbor> Neighbors { get { if ((this.serializing && (this._Neighbors.HasLoadedOrAssignedValues == false))) { return null; } return this._Neighbors; } set { this._Neighbors.Assign(value); } } [Association(Name="Block_Neighbor1", Storage="_Neighbors1", ThisKey="ID", OtherKey="SecondBlockID")] [DataMember(Order=10, EmitDefaultValue=false)] public EntitySet<Neighbor> Neighbors1 { get { if ((this.serializing && (this._Neighbors1.HasLoadedOrAssignedValues == false))) { return null; } return this._Neighbors1; } set { this._Neighbors1.Assign(value); } } [Association(Name="Block_Task", Storage="_Tasks", ThisKey="ID", OtherKey="BlockID")] [DataMember(Order=11, EmitDefaultValue=false)] public EntitySet<Task> Tasks { get { if ((this.serializing && (this._Tasks.HasLoadedOrAssignedValues == false))) { return null; } return this._Tasks; } set { this._Tasks.Assign(value); } } [Association(Name="Block_PlanningPointByBlock", Storage="_PlanningPointByBlocks", ThisKey="ID", OtherKey="BlockID")] [DataMember(Order=12, EmitDefaultValue=false)] public EntitySet<PlanningPointByBlock> PlanningPointByBlocks { get { if ((this.serializing && (this._PlanningPointByBlocks.HasLoadedOrAssignedValues == false))) { return null; } return this._PlanningPointByBlocks; } set { this._PlanningPointByBlocks.Assign(value); } } [Association(Name="Block_ControlPointByBlock", Storage="_ControlPointByBlocks", ThisKey="ID", OtherKey="BlockID")] [DataMember(Order=13, EmitDefaultValue=false)] public EntitySet<ControlPointByBlock> ControlPointByBlocks { get { if ((this.serializing && (this._ControlPointByBlocks.HasLoadedOrAssignedValues == false))) { return null; } return this._ControlPointByBlocks; } set { this._ControlPointByBlocks.Assign(value); } } [Association(Name="Division_Block", Storage="_Division", ThisKey="DivisionID", OtherKey="ID", IsForeignKey=true, DeleteOnNull=true, DeleteRule="CASCADE")] public Division Division { get { return this._Division.Entity; } set { Division previousValue = this._Division.Entity; if (((previousValue != value) || (this._Division.HasLoadedOrAssignedValue == false))) { this.SendPropertyChanging(); if ((previousValue != null)) { this._Division.Entity = null; previousValue.Blocks.Remove(this); } this._Division.Entity = value; if ((value != null)) { value.Blocks.Add(this); this._DivisionID = value.ID; } else { this._DivisionID = default(long); } this.SendPropertyChanged("Division"); } } } public event PropertyChangingEventHandler PropertyChanging; public event PropertyChangedEventHandler PropertyChanged; protected virtual void SendPropertyChanging() { if ((this.PropertyChanging != null)) { this.PropertyChanging(this, emptyChangingEventArgs); } } protected virtual void SendPropertyChanged(String propertyName) { if ((this.PropertyChanged != null)) { this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName)); } } private void attach_BlockByWorkstations(BlockByWorkstation entity) { this.SendPropertyChanging(); entity.Block = this; } private void detach_BlockByWorkstations(BlockByWorkstation entity) { this.SendPropertyChanging(); entity.Block = null; } private void attach_PlanningPointAppropriations(PlanningPointAppropriation entity) { this.SendPropertyChanging(); entity.Block = this; } private void detach_PlanningPointAppropriations(PlanningPointAppropriation entity) { this.SendPropertyChanging(); entity.Block = null; } private void attach_Neighbors(Neighbor entity) { this.SendPropertyChanging(); entity.FirstBlock = this; } private void detach_Neighbors(Neighbor entity) { this.SendPropertyChanging(); entity.FirstBlock = null; } private void attach_Neighbors1(Neighbor entity) { this.SendPropertyChanging(); entity.SecondBlock = this; } private void detach_Neighbors1(Neighbor entity) { this.SendPropertyChanging(); entity.SecondBlock = null; } private void attach_Tasks(Task entity) { this.SendPropertyChanging(); entity.Block = this; } private void detach_Tasks(Task entity) { this.SendPropertyChanging(); entity.Block = null; } private void attach_PlanningPointByBlocks(PlanningPointByBlock entity) { this.SendPropertyChanging(); entity.Block = this; } private void detach_PlanningPointByBlocks(PlanningPointByBlock entity) { this.SendPropertyChanging(); entity.Block = null; } private void attach_ControlPointByBlocks(ControlPointByBlock entity) { this.SendPropertyChanging(); entity.Block = this; } private void detach_ControlPointByBlocks(ControlPointByBlock entity) { this.SendPropertyChanging(); entity.Block = null; } private void Initialize() { this._BlockByWorkstations = new EntitySet<BlockByWorkstation>(new Action<BlockByWorkstation>(this.attach_BlockByWorkstations), new Action<BlockByWorkstation>(this.detach_BlockByWorkstations)); this._PlanningPointAppropriations = new EntitySet<PlanningPointAppropriation>(new Action<PlanningPointAppropriation>(this.attach_PlanningPointAppropriations), new Action<PlanningPointAppropriation>(this.detach_PlanningPointAppropriations)); this._Neighbors = new EntitySet<Neighbor>(new Action<Neighbor>(this.attach_Neighbors), new Action<Neighbor>(this.detach_Neighbors)); this._Neighbors1 = new EntitySet<Neighbor>(new Action<Neighbor>(this.attach_Neighbors1), new Action<Neighbor>(this.detach_Neighbors1)); this._Tasks = new EntitySet<Task>(new Action<Task>(this.attach_Tasks), new Action<Task>(this.detach_Tasks)); this._PlanningPointByBlocks = new EntitySet<PlanningPointByBlock>(new Action<PlanningPointByBlock>(this.attach_PlanningPointByBlocks), new Action<PlanningPointByBlock>(this.detach_PlanningPointByBlocks)); this._ControlPointByBlocks = new EntitySet<ControlPointByBlock>(new Action<ControlPointByBlock>(this.attach_ControlPointByBlocks), new Action<ControlPointByBlock>(this.detach_ControlPointByBlocks)); this._Division = default(EntityRef<Division>); OnCreated(); } [OnDeserializing()] [System.ComponentModel.EditorBrowsableAttribute(EditorBrowsableState.Never)] public void OnDeserializing(StreamingContext context) { this.Initialize(); } [OnSerializing()] [System.ComponentModel.EditorBrowsableAttribute(EditorBrowsableState.Never)] public void OnSerializing(StreamingContext context) { this.serializing = true; } [OnSerialized()] [System.ComponentModel.EditorBrowsableAttribute(EditorBrowsableState.Never)] public void OnSerialized(StreamingContext context) { this.serializing = false; } } App.config: <?xml version="1.0" encoding="utf-8" ?> <configuration> <system.web> <compilation debug="true" /> </system.web>  <system.serviceModel> <services> <service behaviorConfiguration="debugging" name="DBServicesLibrary.DBService"> </service> </services> <behaviors> <serviceBehaviors> <behavior name="DBServicesLibrary.DBServiceBehavior">  <serviceMetadata httpGetEnabled="True"/>  <serviceDebug includeExceptionDetailInFaults="False" /> </behavior> <behavior name="debugging"> <serviceDebug includeExceptionDetailInFaults="true"/> </behavior> </serviceBehaviors> </behaviors> </system.serviceModel> </configuration> Host part: ServiceHost svh = new ServiceHost(typeof(DBService)); svh.AddServiceEndpoint( typeof(DBServices.Contract.IDBService), new NetTcpBinding(), "net.tcp://localhost:8000"); Client part: ChannelFactory<DBServices.Contract.IDBService> scf; scf = new ChannelFactory<DBServices.Contract.IDBService>(new NetTcpBinding(),"net.tcp://localhost:8000"); _serv = scf.CreateChannel(); ((IContextChannel)_serv).OperationTimeout = new TimeSpan(0, 5, 0);

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How can I get penetration depth from Minkowski Portal Refinement / Xenocollide?

- by Raven Dreamer

I recently got an implementation of Minkowski Portal Refinement (MPR) successfully detecting collision. Even better, my implementation returns a good estimate (local minimum) direction for the minimum penetration depth. So I took a stab at adjusting the algorithm to return the penetration depth in an arbitrary direction, and was modestly successful - my altered method works splendidly for face-edge collision resolution! What it doesn't currently do, is correctly provide the minimum penetration depth for edge-edge scenarios, such as the case on the right: What I perceive to be happening, is that my current method returns the minimum penetration depth to the nearest vertex - which works fine when the collision is actually occurring on the plane of that vertex, but not when the collision happens along an edge. Is there a way I can alter my method to return the penetration depth to the point of collision, rather than the nearest vertex? Here's the method that's supposed to return the minimum penetration distance along a specific direction: public static Vector3 CalcMinDistance(List<Vector3> shape1, List<Vector3> shape2, Vector3 dir) { //holding variables Vector3 n = Vector3.zero; Vector3 swap = Vector3.zero; // v0 = center of Minkowski sum v0 = Vector3.zero; // Avoid case where centers overlap -- any direction is fine in this case //if (v0 == Vector3.zero) return Vector3.zero; //always pass in a valid direction. // v1 = support in direction of origin n = -dir; //get the differnce of the minkowski sum Vector3 v11 = GetSupport(shape1, -n); Vector3 v12 = GetSupport(shape2, n); v1 = v12 - v11; //if the support point is not in the direction of the origin if (v1.Dot(n) <= 0) { //Debug.Log("Could find no points this direction"); return Vector3.zero; } // v2 - support perpendicular to v1,v0 n = v1.Cross(v0); if (n == Vector3.zero) { //v1 and v0 are parallel, which means //the direction leads directly to an endpoint n = v1 - v0; //shortest distance is just n //Debug.Log("2 point return"); return n; } //get the new support point Vector3 v21 = GetSupport(shape1, -n); Vector3 v22 = GetSupport(shape2, n); v2 = v22 - v21; if (v2.Dot(n) <= 0) { //can't reach the origin in this direction, ergo, no collision //Debug.Log("Could not reach edge?"); return Vector2.zero; } // Determine whether origin is on + or - side of plane (v1,v0,v2) //tests linesegments v0v1 and v0v2 n = (v1 - v0).Cross(v2 - v0); float dist = n.Dot(v0); // If the origin is on the - side of the plane, reverse the direction of the plane if (dist > 0) { //swap the winding order of v1 and v2 swap = v1; v1 = v2; v2 = swap; //swap the winding order of v11 and v12 swap = v12; v12 = v11; v11 = swap; //swap the winding order of v11 and v12 swap = v22; v22 = v21; v21 = swap; //and swap the plane normal n = -n; } /// // Phase One: Identify a portal while (true) { // Obtain the support point in a direction perpendicular to the existing plane // Note: This point is guaranteed to lie off the plane Vector3 v31 = GetSupport(shape1, -n); Vector3 v32 = GetSupport(shape2, n); v3 = v32 - v31; if (v3.Dot(n) <= 0) { //can't enclose the origin within our tetrahedron //Debug.Log("Could not reach edge after portal?"); return Vector3.zero; } // If origin is outside (v1,v0,v3), then eliminate v2 and loop if (v1.Cross(v3).Dot(v0) < 0) { //failed to enclose the origin, adjust points; v2 = v3; v21 = v31; v22 = v32; n = (v1 - v0).Cross(v3 - v0); continue; } // If origin is outside (v3,v0,v2), then eliminate v1 and loop if (v3.Cross(v2).Dot(v0) < 0) { //failed to enclose the origin, adjust points; v1 = v3; v11 = v31; v12 = v32; n = (v3 - v0).Cross(v2 - v0); continue; } bool hit = false; /// // Phase Two: Refine the portal int phase2 = 0; // We are now inside of a wedge... while (phase2 < 20) { phase2++; // Compute normal of the wedge face n = (v2 - v1).Cross(v3 - v1); n.Normalize(); // Compute distance from origin to wedge face float d = n.Dot(v1); // If the origin is inside the wedge, we have a hit if (d > 0 ) { //Debug.Log("Do plane test here"); float T = n.Dot(v2) / n.Dot(dir); Vector3 pointInPlane = (dir * T); return pointInPlane; } // Find the support point in the direction of the wedge face Vector3 v41 = GetSupport(shape1, -n); Vector3 v42 = GetSupport(shape2, n); v4 = v42 - v41; float delta = (v4 - v3).Dot(n); float separation = -(v4.Dot(n)); if (delta <= kCollideEpsilon || separation >= 0) { //Debug.Log("Non-convergance detected"); //Debug.Log("Do plane test here"); return Vector3.zero; } // Compute the tetrahedron dividing face (v4,v0,v1) float d1 = v4.Cross(v1).Dot(v0); // Compute the tetrahedron dividing face (v4,v0,v2) float d2 = v4.Cross(v2).Dot(v0); // Compute the tetrahedron dividing face (v4,v0,v3) float d3 = v4.Cross(v3).Dot(v0); if (d1 < 0) { if (d2 < 0) { // Inside d1 & inside d2 ==> eliminate v1 v1 = v4; v11 = v41; v12 = v42; } else { // Inside d1 & outside d2 ==> eliminate v3 v3 = v4; v31 = v41; v32 = v42; } } else { if (d3 < 0) { // Outside d1 & inside d3 ==> eliminate v2 v2 = v4; v21 = v41; v22 = v42; } else { // Outside d1 & outside d3 ==> eliminate v1 v1 = v4; v11 = v41; v12 = v42; } } } return Vector3.zero; } }

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Developing web apps using ASP.NET MVC 3, Razor and EF Code First - Part 1

- by shiju

In this post, I will demonstrate web application development using ASP. NET MVC 3, Razor and EF code First. This post will also cover Dependency Injection using Unity 2.0 and generic Repository and Unit of Work for EF Code First. The following frameworks will be used for this step by step tutorial. ASP.NET MVC 3 EF Code First CTP 5 Unity 2.0 Define Domain Model Let’s create domain model for our simple web application Category class public class Category { public int CategoryId { get; set; } [Required(ErrorMessage = "Name Required")] [StringLength(25, ErrorMessage = "Must be less than 25 characters")] public string Name { get; set;} public string Description { get; set; } public virtual ICollection<Expense> Expenses { get; set; } } Expense class public class Expense { public int ExpenseId { get; set; } public string Transaction { get; set; } public DateTime Date { get; set; } public double Amount { get; set; } public int CategoryId { get; set; } public virtual Category Category { get; set; } } We have two domain entities - Category and Expense. A single category contains a list of expense transactions and every expense transaction should have a Category. In this post, we will be focusing on CRUD operations for the entity Category and will be working on the Expense entity with a View Model object in the later post. And the source code for this application will be refactored over time. The above entities are very simple POCO (Plain Old CLR Object) classes and the entity Category is decorated with validation attributes in the System.ComponentModel.DataAnnotations namespace. Now we want to use these entities for defining model objects for the Entity Framework 4. Using the Code First approach of Entity Framework, we can first define the entities by simply writing POCO classes without any coupling with any API or database library. This approach lets you focus on domain model which will enable Domain-Driven Development for applications. EF code first support is currently enabled with a separate API that is runs on top of the Entity Framework 4. EF Code First is reached CTP 5 when I am writing this article. Creating Context Class for Entity Framework We have created our domain model and let’s create a class in order to working with Entity Framework Code First. For this, you have to download EF Code First CTP 5 and add reference to the assembly EntitFramework.dll. You can also use NuGet to download add reference to EEF Code First. public class MyFinanceContext : DbContext { public MyFinanceContext() : base("MyFinance") { } public DbSet<Category> Categories { get; set; } public DbSet<Expense> Expenses { get; set; } } The above class MyFinanceContext is derived from DbContext that can connect your model classes to a database. The MyFinanceContext class is mapping our Category and Expense class into database tables Categories and Expenses using DbSet<TEntity> where TEntity is any POCO class. When we are running the application at first time, it will automatically create the database. EF code-first look for a connection string in web.config or app.config that has the same name as the dbcontext class. If it is not find any connection string with the convention, it will automatically create database in local SQL Express database by default and the name of the database will be same name as the dbcontext class. You can also define the name of database in constructor of the the dbcontext class. Unlike NHibernate, we don’t have to use any XML based mapping files or Fluent interface for mapping between our model and database. The model classes of Code First are working on the basis of conventions and we can also use a fluent API to refine our model. The convention for primary key is ‘Id’ or ‘<class name>Id’. If primary key properties are detected with type ‘int’, ‘long’ or ‘short’, they will automatically registered as identity columns in the database by default. Primary key detection is not case sensitive. We can define our model classes with validation attributes in the System.ComponentModel.DataAnnotations namespace and it automatically enforces validation rules when a model object is updated or saved. Generic Repository for EF Code First We have created model classes and dbcontext class. Now we have to create generic repository pattern for data persistence with EF code first. If you don’t know about the repository pattern, checkout Martin Fowler’s article on Repository Let’s create a generic repository to working with DbContext and DbSet generics. public interface IRepository<T> where T : class { void Add(T entity); void Delete(T entity); T GetById(long Id); IEnumerable<T> All(); } RepositoryBasse – Generic Repository class public abstract class RepositoryBase<T> where T : class { private MyFinanceContext database; private readonly IDbSet<T> dbset; protected RepositoryBase(IDatabaseFactory databaseFactory) { DatabaseFactory = databaseFactory; dbset = Database.Set<T>(); } protected IDatabaseFactory DatabaseFactory { get; private set; } protected MyFinanceContext Database { get { return database ?? (database = DatabaseFactory.Get()); } } public virtual void Add(T entity) { dbset.Add(entity); } public virtual void Delete(T entity) { dbset.Remove(entity); } public virtual T GetById(long id) { return dbset.Find(id); } public virtual IEnumerable<T> All() { return dbset.ToList(); } } DatabaseFactory class public class DatabaseFactory : Disposable, IDatabaseFactory { private MyFinanceContext database; public MyFinanceContext Get() { return database ?? (database = new MyFinanceContext()); } protected override void DisposeCore() { if (database != null) database.Dispose(); } } Unit of Work If you are new to Unit of Work pattern, checkout Fowler’s article on Unit of Work . According to Martin Fowler, the Unit of Work pattern "maintains a list of objects affected by a business transaction and coordinates the writing out of changes and the resolution of concurrency problems." Let’s create a class for handling Unit of Work public interface IUnitOfWork { void Commit(); } UniOfWork class public class UnitOfWork : IUnitOfWork { private readonly IDatabaseFactory databaseFactory; private MyFinanceContext dataContext; public UnitOfWork(IDatabaseFactory databaseFactory) { this.databaseFactory = databaseFactory; } protected MyFinanceContext DataContext { get { return dataContext ?? (dataContext = databaseFactory.Get()); } } public void Commit() { DataContext.Commit(); } } The Commit method of the UnitOfWork will call the commit method of MyFinanceContext class and it will execute the SaveChanges method of DbContext class. Repository class for Category In this post, we will be focusing on the persistence against Category entity and will working on other entities in later post. Let’s create a repository for handling CRUD operations for Category using derive from a generic Repository RepositoryBase<T>. public class CategoryRepository: RepositoryBase<Category>, ICategoryRepository { public CategoryRepository(IDatabaseFactory databaseFactory) : base(databaseFactory) { } } public interface ICategoryRepository : IRepository<Category> { } If we need additional methods than generic repository for the Category, we can define in the CategoryRepository. Dependency Injection using Unity 2.0 If you are new to Inversion of Control/ Dependency Injection or Unity, please have a look on my articles at http://weblogs.asp.net/shijuvarghese/archive/tags/IoC/default.aspx. I want to create a custom lifetime manager for Unity to store container in the current HttpContext. public class HttpContextLifetimeManager<T> : LifetimeManager, IDisposable { public override object GetValue() { return HttpContext.Current.Items[typeof(T).AssemblyQualifiedName]; } public override void RemoveValue() { HttpContext.Current.Items.Remove(typeof(T).AssemblyQualifiedName); } public override void SetValue(object newValue) { HttpContext.Current.Items[typeof(T).AssemblyQualifiedName] = newValue; } public void Dispose() { RemoveValue(); } } Let’s create controller factory for Unity in the ASP.NET MVC 3 application. public class UnityControllerFactory : DefaultControllerFactory { IUnityContainer container; public UnityControllerFactory(IUnityContainer container) { this.container = container; } protected override IController GetControllerInstance(RequestContext reqContext, Type controllerType) { IController controller; if (controllerType == null) throw new HttpException( 404, String.Format( "The controller for path '{0}' could not be found" + "or it does not implement IController.", reqContext.HttpContext.Request.Path)); if (!typeof(IController).IsAssignableFrom(controllerType)) throw new ArgumentException( string.Format( "Type requested is not a controller: {0}", controllerType.Name), "controllerType"); try { controller= container.Resolve(controllerType) as IController; } catch (Exception ex) { throw new InvalidOperationException(String.Format( "Error resolving controller {0}", controllerType.Name), ex); } return controller; } } Configure contract and concrete types in Unity Let’s configure our contract and concrete types in Unity for resolving our dependencies. private void ConfigureUnity() { //Create UnityContainer IUnityContainer container = new UnityContainer() .RegisterType<IDatabaseFactory, DatabaseFactory>(new HttpContextLifetimeManager<IDatabaseFactory>()) .RegisterType<IUnitOfWork, UnitOfWork>(new HttpContextLifetimeManager<IUnitOfWork>()) .RegisterType<ICategoryRepository, CategoryRepository>(new HttpContextLifetimeManager<ICategoryRepository>()); //Set container for Controller Factory ControllerBuilder.Current.SetControllerFactory( new UnityControllerFactory(container)); } In the above ConfigureUnity method, we are registering our types onto Unity container with custom lifetime manager HttpContextLifetimeManager. Let’s call ConfigureUnity method in the Global.asax.cs for set controller factory for Unity and configuring the types with Unity. protected void Application_Start() { AreaRegistration.RegisterAllAreas(); RegisterGlobalFilters(GlobalFilters.Filters); RegisterRoutes(RouteTable.Routes); ConfigureUnity(); } Developing web application using ASP.NET MVC 3 We have created our domain model for our web application and also have created repositories and configured dependencies with Unity container. Now we have to create controller classes and views for doing CRUD operations against the Category entity. Let’s create controller class for Category Category Controller public class CategoryController : Controller { private readonly ICategoryRepository categoryRepository; private readonly IUnitOfWork unitOfWork; public CategoryController(ICategoryRepository categoryRepository, IUnitOfWork unitOfWork) { this.categoryRepository = categoryRepository; this.unitOfWork = unitOfWork; } public ActionResult Index() { var categories = categoryRepository.All(); return View(categories); } [HttpGet] public ActionResult Edit(int id) { var category = categoryRepository.GetById(id); return View(category); } [HttpPost] public ActionResult Edit(int id, FormCollection collection) { var category = categoryRepository.GetById(id); if (TryUpdateModel(category)) { unitOfWork.Commit(); return RedirectToAction("Index"); } else return View(category); } [HttpGet] public ActionResult Create() { var category = new Category(); return View(category); } [HttpPost] public ActionResult Create(Category category) { if (!ModelState.IsValid) { return View("Create", category); } categoryRepository.Add(category); unitOfWork.Commit(); return RedirectToAction("Index"); } [HttpPost] public ActionResult Delete(int id) { var category = categoryRepository.GetById(id); categoryRepository.Delete(category); unitOfWork.Commit(); var categories = categoryRepository.All(); return PartialView("CategoryList", categories); } } Creating Views in Razor Now we are going to create views in Razor for our ASP.NET MVC 3 application. Let’s create a partial view CategoryList.cshtml for listing category information and providing link for Edit and Delete operations. CategoryList.cshtml @using MyFinance.Helpers; @using MyFinance.Domain; @model IEnumerable<Category> <table> <tr> <th>Actions</th> <th>Name</th> <th>Description</th> </tr> @foreach (var item in Model) { <tr> <td> @Html.ActionLink("Edit", "Edit",new { id = item.CategoryId }) @Ajax.ActionLink("Delete", "Delete", new { id = item.CategoryId }, new AjaxOptions { Confirm = "Delete Expense?", HttpMethod = "Post", UpdateTargetId = "divCategoryList" }) </td> <td> @item.Name </td> <td> @item.Description </td> </tr> } </table> <p> @Html.ActionLink("Create New", "Create") </p> The delete link is providing Ajax functionality using the Ajax.ActionLink. This will call an Ajax request for Delete action method in the CategoryCotroller class. In the Delete action method, it will return Partial View CategoryList after deleting the record. We are using CategoryList view for the Ajax functionality and also for Index view using for displaying list of category information. Let’s create Index view using partial view CategoryList Index.chtml @model IEnumerable<MyFinance.Domain.Category> @{ ViewBag.Title = "Index"; } <h2>Category List</h2> <script src="@Url.Content("~/Scripts/jquery.unobtrusive-ajax.min.js")" type="text/javascript"></script> <div id="divCategoryList"> @Html.Partial("CategoryList", Model) </div> We can call the partial views using Html.Partial helper method. Now we are going to create View pages for insert and update functionality for the Category. Both view pages are sharing common user interface for entering the category information. So I want to create an EditorTemplate for the Category information. We have to create the EditorTemplate with the same name of entity object so that we can refer it on view pages using @Html.EditorFor(model => model) . So let’s create template with name Category. Let’s create view page for insert Category information @model MyFinance.Domain.Category @{ ViewBag.Title = "Save"; } <h2>Create</h2> <script src="@Url.Content("~/Scripts/jquery.validate.min.js")" type="text/javascript"></script> <script src="@Url.Content("~/Scripts/jquery.validate.unobtrusive.min.js")" type="text/javascript"></script> @using (Html.BeginForm()) { @Html.ValidationSummary(true) <fieldset> <legend>Category</legend> @Html.EditorFor(model => model) <p> <input type="submit" value="Create" /> </p> </fieldset> } <div> @Html.ActionLink("Back to List", "Index") </div> ViewStart file In Razor views, we can add a file named _viewstart.cshtml in the views directory and this will be shared among the all views with in the Views directory. The below code in the _viewstart.cshtml, sets the Layout page for every Views in the Views folder. @{ Layout = "~/Views/Shared/_Layout.cshtml"; } Source Code You can download the source code from http://efmvc.codeplex.com/ . The source will be refactored on over time. Summary In this post, we have created a simple web application using ASP.NET MVC 3 and EF Code First. We have discussed on technologies and practices such as ASP.NET MVC 3, Razor, EF Code First, Unity 2, generic Repository and Unit of Work. In my later posts, I will modify the application and will be discussed on more things. Stay tuned to my blog for more posts on step by step application building.

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How to add items to the Document Types context menu.

- by Vizioz Limited

I am currently working on an extension to Umbraco that needed an extra menu item on the Document Types menu in the Settings section, my first thought was to use the BeforeNodeRender event to add the menu item, but this event only fires on the Content and Media menu trees.See: Codeplex Issue 21623The "temporary" solution has been to extend the "loadNodeTypes" class, I say temporary because I assume that the core team may well extend the event functionality to the entire menu tree in the future which would be much better and would prevent you from having to complete override the menu items.This was suggested by Slace on my "is it possible to add an item to the context menu in tree's other than media content" post on the our.umbraco.org site.There are three things you need to do:1) Override the loadNodeTypesusing System.Collections.Generic;using umbraco.interfaces;using umbraco.BusinessLogic.Actions;namespace Vizioz.xMind2Umbraco{ // Note: Remember these menu's might change in future versions of Umbraco public class loadNodeTypesMenu : umbraco.loadNodeTypes { public loadNodeTypesMenu(string application) : base(application) { } protected override void CreateRootNodeActions(ref List<IAction> actions) { actions.Clear(); actions.Add(ActionNew.Instance); actions.Add(xMindImportAction.Instance); actions.Add(ContextMenuSeperator.Instance); actions.Add(ActionImport.Instance); actions.Add(ContextMenuSeperator.Instance); actions.Add(ActionRefresh.Instance); } protected override void CreateAllowedActions(ref List<IAction> actions) { actions.Clear(); actions.Add(ActionCopy.Instance); actions.Add(xMindImportAction.Instance); actions.Add(ContextMenuSeperator.Instance); actions.Add(ActionExport.Instance); actions.Add(ContextMenuSeperator.Instance); actions.Add(ActionDelete.Instance); } }}2) Create a new Action to be used on the menuusing umbraco.interfaces;namespace Vizioz.xMind2Umbraco{ public class xMindImportAction : IAction { #region Implementation of IAction public static xMindImportAction Instance { get { return umbraco.Singleton<xMindImportAction>.Instance; } } public char Letter { get { return 'p'; } } public bool ShowInNotifier { get { return true; } } public bool CanBePermissionAssigned { get { return true; } } public string Icon { get { return "editor/OPEN.gif"; } } public string Alias { get { return "Import from xMind"; } } public string JsFunctionName { get { return "openModal('dialogs/xMindImport.aspx?id=' + nodeID, 'Publish Management', 550, 480);"; } } public string JsSource { get { return string.Empty; } } #endregion }}3) Update the UmbracoAppTree table, my case I changed the following:TreeHandlerTypeFrom: loadNodeTypesTo: loadNodeTypesMenuTreeHandlerAssemblyFrom: umbracoTo: Vizioz.xMind2UmbracoAnd the result is:

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Authenticating clients in the new WCF Http stack

- by cibrax

About this time last year, I wrote a couple of posts about how to use the “Interceptors” from the REST starker kit for implementing several authentication mechanisms like “SAML”, “Basic Authentication” or “OAuth” in the WCF Web programming model. The things have changed a lot since then, and Glenn finally put on our hands a new version of the Web programming model that deserves some attention and I believe will help us a lot to build more Http oriented services in the .NET stack. What you can get today from wcf.codeplex.com is a preview with some cool features like Http Processors (which I already discussed here), a new and improved version of the HttpClient library, Dependency injection and better TDD support among others. However, the framework still does not support an standard way of doing client authentication on the services (This is something planned for the upcoming releases I believe). For that reason, moving the existing authentication interceptors to this new programming model was one of the things I did in the last few days. In order to make authentication simple and easy to extend, I first came up with a model based on what I called “Authentication Interceptors”. An authentication interceptor maps to an existing Http authentication mechanism and implements the following interface, public interface IAuthenticationInterceptor{ string Scheme { get; } bool DoAuthentication(HttpRequestMessage request, HttpResponseMessage response, out IPrincipal principal);} An authentication interceptors basically needs to returns the http authentication schema that implements in the property “Scheme”, and implements the authentication mechanism in the method “DoAuthentication”. As you can see, this last method “DoAuthentication” only relies on the HttpRequestMessage and HttpResponseMessage classes, making the testing of this interceptor very simple (There is no need to do some black magic with the WCF context or messages). After this, I implemented a couple of interceptors for supporting basic authentication and brokered authentication with SAML (using WIF) in my services. The following code illustrates how the basic authentication interceptors looks like. public class BasicAuthenticationInterceptor : IAuthenticationInterceptor{ Func<UsernameAndPassword, bool> userValidation; string realm; public BasicAuthenticationInterceptor(Func<UsernameAndPassword, bool> userValidation, string realm) { if (userValidation == null) throw new ArgumentNullException("userValidation"); if (string.IsNullOrEmpty(realm)) throw new ArgumentNullException("realm"); this.userValidation = userValidation; this.realm = realm; } public string Scheme { get { return "Basic"; } } public bool DoAuthentication(HttpRequestMessage request, HttpResponseMessage response, out IPrincipal principal) { string[] credentials = ExtractCredentials(request); if (credentials.Length == 0 || !AuthenticateUser(credentials[0], credentials[1])) { response.StatusCode = HttpStatusCode.Unauthorized; response.Content = new StringContent("Access denied"); response.Headers.WwwAuthenticate.Add(new AuthenticationHeaderValue("Basic", "realm=" + this.realm)); principal = null; return false; } else { principal = new GenericPrincipal(new GenericIdentity(credentials[0]), new string[] {}); return true; } } private string[] ExtractCredentials(HttpRequestMessage request) { if (request.Headers.Authorization != null && request.Headers.Authorization.Scheme.StartsWith("Basic")) { string encodedUserPass = request.Headers.Authorization.Parameter.Trim(); Encoding encoding = Encoding.GetEncoding("iso-8859-1"); string userPass = encoding.GetString(Convert.FromBase64String(encodedUserPass)); int separator = userPass.IndexOf(':'); string[] credentials = new string[2]; credentials[0] = userPass.Substring(0, separator); credentials[1] = userPass.Substring(separator + 1); return credentials; } return new string[] { }; } private bool AuthenticateUser(string username, string password) { var usernameAndPassword = new UsernameAndPassword { Username = username, Password = password }; if (this.userValidation(usernameAndPassword)) { return true; } return false; }} This interceptor receives in the constructor a callback in the form of a Func delegate for authenticating the user and the “realm”, which is required as part of the implementation. The rest is a general implementation of the basic authentication mechanism using standard http request and response messages. I also implemented another interceptor for authenticating a SAML token with WIF. public class SamlAuthenticationInterceptor : IAuthenticationInterceptor{ SecurityTokenHandlerCollection handlers = null; public SamlAuthenticationInterceptor(SecurityTokenHandlerCollection handlers) { if (handlers == null) throw new ArgumentNullException("handlers"); this.handlers = handlers; } public string Scheme { get { return "saml"; } } public bool DoAuthentication(HttpRequestMessage request, HttpResponseMessage response, out IPrincipal principal) { SecurityToken token = ExtractCredentials(request); if (token != null) { ClaimsIdentityCollection claims = handlers.ValidateToken(token); principal = new ClaimsPrincipal(claims); return true; } else { response.StatusCode = HttpStatusCode.Unauthorized; response.Content = new StringContent("Access denied"); principal = null; return false; } } private SecurityToken ExtractCredentials(HttpRequestMessage request) { if (request.Headers.Authorization != null && request.Headers.Authorization.Scheme == "saml") { XmlTextReader xmlReader = new XmlTextReader(new StringReader(request.Headers.Authorization.Parameter)); var col = SecurityTokenHandlerCollection.CreateDefaultSecurityTokenHandlerCollection(); SecurityToken token = col.ReadToken(xmlReader); return token; } return null; }}This implementation receives a “SecurityTokenHandlerCollection” instance as part of the constructor. This class is part of WIF, and basically represents a collection of token managers to know how to handle specific xml authentication tokens (SAML is one of them). I also created a set of extension methods for injecting these interceptors as part of a service route when the service is initialized. var basicAuthentication = new BasicAuthenticationInterceptor((u) => true, "ContactManager");var samlAuthentication = new SamlAuthenticationInterceptor(serviceConfiguration.SecurityTokenHandlers); // use MEF for providing instancesvar catalog = new AssemblyCatalog(typeof(Global).Assembly);var container = new CompositionContainer(catalog);var configuration = new ContactManagerConfiguration(container); RouteTable.Routes.AddServiceRoute<ContactResource>("contact", configuration, basicAuthentication, samlAuthentication);RouteTable.Routes.AddServiceRoute<ContactsResource>("contacts", configuration, basicAuthentication, samlAuthentication); In the code above, I am injecting the basic authentication and saml authentication interceptors in the “contact” and “contacts” resource implementations that come as samples in the code preview. I will use another post to discuss more in detail how the brokered authentication with SAML model works with this new WCF Http bits. The code is available to download in this location.

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Enabling Service Availability in WCF Services

- by cibrax

It is very important for the enterprise to know which services are operational at any given point. There are many factors that can affect the availability of the services, some of them are external like a database not responding or any dependant service not working. However, in some cases, you only want to know whether a service is up or down, so a simple heart-beat mechanism with “Ping” messages would do the trick. Unfortunately, WCF does not provide a built-in mechanism to support this functionality, and you probably don’t to implement a “Ping” operation in any service that you have out there. For solving this in a generic way, there is a WCF extensibility point that comes to help us, the “Operation Invokers”. In a nutshell, an operation invoker is the class responsible invoking the service method with a set of parameters and generate the output parameters with the return value. What I am going to do here is to implement a custom operation invoker that intercepts any call to the service, and detects whether a “Ping” header was attached to the message. If the “Ping” header is detected, the operation invoker returns a new header to tell the client that the service is alive, and the real operation execution is omitted. In that way, we have a simple heart beat mechanism based on the messages that include a "Ping” header, so the client application can determine at any point whether the service is up or down. My operation invoker wraps the default implementation attached by default to any operation by WCF. internal class PingOperationInvoker : IOperationInvoker { IOperationInvoker innerInvoker; object[] outputs = null; object returnValue = null; public const string PingHeaderName = "Ping"; public const string PingHeaderNamespace = "http://tellago.serviceModel"; public PingOperationInvoker(IOperationInvoker innerInvoker, OperationDescription description) { this.innerInvoker = innerInvoker; outputs = description.SyncMethod.GetParameters() .Where(p => p.IsOut) .Select(p => DefaultForType(p.ParameterType)).ToArray(); var returnValue = DefaultForType(description.SyncMethod.ReturnType); } private static object DefaultForType(Type targetType) { return targetType.IsValueType ? Activator.CreateInstance(targetType) : null; } public object Invoke(object instance, object[] inputs, out object[] outputs) { object returnValue; if (Invoke(out returnValue, out outputs)) { return returnValue; } else { return this.innerInvoker.Invoke(instance, inputs, out outputs); } } private bool Invoke(out object returnValue, out object[] outputs) { object untypedProperty = null; if (OperationContext.Current .IncomingMessageProperties.TryGetValue(HttpRequestMessageProperty.Name, out untypedProperty)) { var httpRequestProperty = untypedProperty as HttpRequestMessageProperty; if (httpRequestProperty != null) { if (httpRequestProperty.Headers[PingHeaderName] != null) { outputs = this.outputs; if (OperationContext.Current .IncomingMessageProperties.TryGetValue(HttpRequestMessageProperty.Name, out untypedProperty)) { var httpResponseProperty = untypedProperty as HttpResponseMessageProperty; httpResponseProperty.Headers.Add(PingHeaderName, "Ok"); } returnValue = this.returnValue; return true; } } } var headers = OperationContext.Current.IncomingMessageHeaders; if (headers.FindHeader(PingHeaderName, PingHeaderNamespace) > -1) { outputs = this.outputs; MessageHeader<string> header = new MessageHeader<string>("Ok"); var untyped = header.GetUntypedHeader(PingHeaderName, PingHeaderNamespace); OperationContext.Current.OutgoingMessageHeaders.Add(untyped); returnValue = this.returnValue; return true; } returnValue = null; outputs = null; return false; } } The implementation above looks for the “Ping” header either in the Http Request or the Soap message. The next step is to implement a behavior for attaching this operation invoker to the services we want to monitor. [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class, AllowMultiple = false, Inherited = true)] public class PingBehavior : Attribute, IServiceBehavior, IOperationBehavior { public void AddBindingParameters(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase, Collection<ServiceEndpoint> endpoints, BindingParameterCollection bindingParameters) { } public void ApplyDispatchBehavior(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { } public void Validate(ServiceDescription serviceDescription, ServiceHostBase serviceHostBase) { foreach (var endpoint in serviceDescription.Endpoints) { foreach (var operation in endpoint.Contract.Operations) { if (operation.Behaviors.Find<PingBehavior>() == null) operation.Behaviors.Add(this); } } } public void AddBindingParameters(OperationDescription operationDescription, BindingParameterCollection bindingParameters) { } public void ApplyClientBehavior(OperationDescription operationDescription, ClientOperation clientOperation) { } public void ApplyDispatchBehavior(OperationDescription operationDescription, DispatchOperation dispatchOperation) { dispatchOperation.Invoker = new PingOperationInvoker(dispatchOperation.Invoker, operationDescription); } public void Validate(OperationDescription operationDescription) { } } As an operation invoker can only be added in an “operation behavior”, a trick I learned in the past is that you can implement a service behavior as well and use the “Validate” method to inject it in all the operations, so the final configuration is much easier and cleaner. You only need to decorate the service with a simple attribute to enable the “Ping” functionality. [PingBehavior] public class HelloWorldService : IHelloWorld { public string Hello(string name) { return "Hello " + name; } } On the other hand, the client application needs to send a dummy message with a “Ping” header to detect whether the service is available or not. In order to simplify this task, I created a extension method in the WCF client channel to do this work. public static class ClientChannelExtensions { const string PingNamespace = "http://tellago.serviceModel"; const string PingName = "Ping"; public static bool IsAvailable<TChannel>(this IClientChannel channel, Action<TChannel> operation) { try { using (OperationContextScope scope = new OperationContextScope(channel)) { MessageHeader<string> header = new MessageHeader<string>(PingName); var untyped = header.GetUntypedHeader(PingName, PingNamespace); OperationContext.Current.OutgoingMessageHeaders.Add(untyped); try { operation((TChannel)channel); var headers = OperationContext.Current.IncomingMessageHeaders; if (headers.Any(h => h.Name == PingName && h.Namespace == PingNamespace)) { return true; } else { return false; } } catch (CommunicationException) { return false; } } } catch (Exception) { return false; } } } This extension method basically adds a “Ping” header to the request message, executes the operation passed as argument (Action<TChannel> operation), and looks for the corresponding “Ping” header in the response to see the results. The client application can use this extension with a single line of code, var client = new ServiceReference.HelloWorldClient(); var isAvailable = client.InnerChannel.IsAvailable<IHelloWorld>((c) => c.Hello(null)); The “isAvailable” variable will tell the client application whether the service is available or not. You can download the complete implementation from this location.

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More Fun with C# Iterators and Generators

- by James Michael Hare

In my last post, I talked quite a bit about iterators and how they can be really powerful tools for filtering a list of items down to a subset of items. This had both pros and cons over returning a full collection, which, in summary, were: Pros: If traversal is only partial, does not have to visit rest of collection. If evaluation method is costly, only incurs that cost on elements visited. Adds little to no garbage collection pressure. Cons: Very slight performance impact if you know caller will always consume all items in collection. And as we saw in the last post, that con for the cost was very, very small and only really became evident on very tight loops consuming very large lists completely. One of the key items to note, though, is the garbage! In the traditional (return a new collection) method, if you have a 1,000,000 element collection, and wish to transform or filter it in some way, you have to allocate space for that copy of the collection. That is, say you have a collection of 1,000,000 items and you want to double every item in the collection. Well, that means you have to allocate a collection to hold those 1,000,000 items to return, which is a lot especially if you are just going to use it once and toss it. Iterators, though, don't have this problem. Each time you visit the node, it would return the doubled value of the node (in this example) and not allocate a second collection of 1,000,000 doubled items. Do you see the distinction? In both cases, we're consuming 1,000,000 items. But in one case we pass back each doubled item which is just an int (for example's sake) on the stack and in the other case, we allocate a list containing 1,000,000 items which then must be garbage collected. So iterators in C# are pretty cool, eh? Well, here's one more thing a C# iterator can do that a traditional "return a new collection" transformation can't! It can return **unbounded** collections! I know, I know, that smells a lot like an infinite loop, eh? Yes and no. Basically, you're relying on the caller to put the bounds on the list, and as long as the caller doesn't you keep going. Consider this example: public static class Fibonacci { // returns the infinite fibonacci sequence public static IEnumerable<int> Sequence() { int iteration = 0; int first = 1; int second = 1; int current = 0; while (true) { if (iteration++ < 2) { current = 1; } else { current = first + second; second = first; first = current; } yield return current; } } } Whoa, you say! Yes, that's an infinite loop! What the heck is going on there? Yes, that was intentional. Would it be better to have a fibonacci sequence that returns only a specific number of items? Perhaps, but that wouldn't give you the power to defer the execution to the caller. The beauty of this function is it is as infinite as the sequence itself! The fibonacci sequence is unbounded, and so is this method. It will continue to return fibonacci numbers for as long as you ask for them. Now that's not something you can do with a traditional method that would return a collection of ints representing each number. In that case you would eventually run out of memory as you got to higher and higher numbers. This method, though, never runs out of memory. Now, that said, you do have to know when you use it that it is an infinite collection and bound it appropriately. Fortunately, Linq provides a lot of these extension methods for you! Let's say you only want the first 10 fibonacci numbers: foreach(var fib in Fibonacci.Sequence().Take(10)) { Console.WriteLine(fib); } Or let's say you only want the fibonacci numbers that are less than 100: foreach(var fib in Fibonacci.Sequence().TakeWhile(f => f < 100)) { Console.WriteLine(fib); } So, you see, one of the nice things about iterators is their power to work with virtually any size (even infinite) collections without adding the garbage collection overhead of making new collections. You can also do fun things like this to make a more "fluent" interface for for loops: // A set of integer generator extension methods public static class IntExtensions { // Begins counting to inifity, use To() to range this. public static IEnumerable<int> Every(this int start) { // deliberately avoiding condition because keeps going // to infinity for as long as values are pulled. for (var i = start; ; ++i) { yield return i; } } // Begins counting to infinity by the given step value, use To() to public static IEnumerable<int> Every(this int start, int byEvery) { // deliberately avoiding condition because keeps going // to infinity for as long as values are pulled. for (var i = start; ; i += byEvery) { yield return i; } } // Begins counting to inifity, use To() to range this. public static IEnumerable<int> To(this int start, int end) { for (var i = start; i <= end; ++i) { yield return i; } } // Ranges the count by specifying the upper range of the count. public static IEnumerable<int> To(this IEnumerable<int> collection, int end) { return collection.TakeWhile(item => item <= end); } } Note that there are two versions of each method. One that starts with an int and one that starts with an IEnumerable<int>. This is to allow more power in chaining from either an existing collection or from an int. This lets you do things like: // count from 1 to 30 foreach(var i in 1.To(30)) { Console.WriteLine(i); } // count from 1 to 10 by 2s foreach(var i in 0.Every(2).To(10)) { Console.WriteLine(i); } // or, if you want an infinite sequence counting by 5s until something inside breaks you out... foreach(var i in 0.Every(5)) { if (someCondition) { break; } ... } Yes, those are kinda play functions and not particularly useful, but they show some of the power of generators and extension methods to form a fluid interface. So what do you think? What are some of your favorite generators and iterators?

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C#/.NET Little Wonders: The Generic Func Delegates

- by James Michael Hare

Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Back in one of my three original “Little Wonders” Trilogy of posts, I had listed generic delegates as one of the Little Wonders of .NET. Later, someone posted a comment saying said that they would love more detail on the generic delegates and their uses, since my original entry just scratched the surface of them. Last week, I began our look at some of the handy generic delegates built into .NET with a description of delegates in general, and the Action family of delegates. For this week, I’ll launch into a look at the Func family of generic delegates and how they can be used to support generic, reusable algorithms and classes. Quick Delegate Recap Delegates are similar to function pointers in C++ in that they allow you to store a reference to a method. They can store references to either static or instance methods, and can actually be used to chain several methods together in one delegate. Delegates are very type-safe and can be satisfied with any standard method, anonymous method, or a lambda expression. They can also be null as well (refers to no method), so care should be taken to make sure that the delegate is not null before you invoke it. Delegates are defined using the keyword delegate, where the delegate’s type name is placed where you would typically place the method name: 1: // This delegate matches any method that takes string, returns nothing 2: public delegate void Log(string message); This delegate defines a delegate type named Log that can be used to store references to any method(s) that satisfies its signature (whether instance, static, lambda expression, etc.). Delegate instances then can be assigned zero (null) or more methods using the operator = which replaces the existing delegate chain, or by using the operator += which adds a method to the end of a delegate chain: 1: // creates a delegate instance named currentLogger defaulted to Console.WriteLine (static method) 2: Log currentLogger = Console.Out.WriteLine; 3: 4: // invokes the delegate, which writes to the console out 5: currentLogger("Hi Standard Out!"); 6: 7: // append a delegate to Console.Error.WriteLine to go to std error 8: currentLogger += Console.Error.WriteLine; 9: 10: // invokes the delegate chain and writes message to std out and std err 11: currentLogger("Hi Standard Out and Error!"); While delegates give us a lot of power, it can be cumbersome to re-create fairly standard delegate definitions repeatedly, for this purpose the generic delegates were introduced in various stages in .NET. These support various method types with particular signatures. Note: a caveat with generic delegates is that while they can support multiple parameters, they do not match methods that contains ref or out parameters. If you want to a delegate to represent methods that takes ref or out parameters, you will need to create a custom delegate. We’ve got the Func… delegates Just like it’s cousin, the Action delegate family, the Func delegate family gives us a lot of power to use generic delegates to make classes and algorithms more generic. Using them keeps us from having to define a new delegate type when need to make a class or algorithm generic. Remember that the point of the Action delegate family was to be able to perform an “action” on an item, with no return results. Thus Action delegates can be used to represent most methods that take 0 to 16 arguments but return void. You can assign a method The Func delegate family was introduced in .NET 3.5 with the advent of LINQ, and gives us the power to define a function that can be called on 0 to 16 arguments and returns a result. Thus, the main difference between Action and Func, from a delegate perspective, is that Actions return nothing, but Funcs return a result. The Func family of delegates have signatures as follows: Func<TResult> – matches a method that takes no arguments, and returns value of type TResult. Func<T, TResult> – matches a method that takes an argument of type T, and returns value of type TResult. Func<T1, T2, TResult> – matches a method that takes arguments of type T1 and T2, and returns value of type TResult. Func<T1, T2, …, TResult> – and so on up to 16 arguments, and returns value of type TResult. These are handy because they quickly allow you to be able to specify that a method or class you design will perform a function to produce a result as long as the method you specify meets the signature. For example, let’s say you were designing a generic aggregator, and you wanted to allow the user to define how the values will be aggregated into the result (i.e. Sum, Min, Max, etc…). To do this, we would ask the user of our class to pass in a method that would take the current total, the next value, and produce a new total. A class like this could look like: 1: public sealed class Aggregator<TValue, TResult> 2: { 3: // holds method that takes previous result, combines with next value, creates new result 4: private Func<TResult, TValue, TResult> _aggregationMethod; 5: 6: // gets or sets the current result of aggregation 7: public TResult Result { get; private set; } 8: 9: // construct the aggregator given the method to use to aggregate values 10: public Aggregator(Func<TResult, TValue, TResult> aggregationMethod = null) 11: { 12: if (aggregationMethod == null) throw new ArgumentNullException("aggregationMethod"); 13: 14: _aggregationMethod = aggregationMethod; 15: } 16: 17: // method to add next value 18: public void Aggregate(TValue nextValue) 19: { 20: // performs the aggregation method function on the current result and next and sets to current result 21: Result = _aggregationMethod(Result, nextValue); 22: } 23: } Of course, LINQ already has an Aggregate extension method, but that works on a sequence of IEnumerable<T>, whereas this is designed to work more with aggregating single results over time (such as keeping track of a max response time for a service). We could then use this generic aggregator to find the sum of a series of values over time, or the max of a series of values over time (among other things): 1: // creates an aggregator that adds the next to the total to sum the values 2: var sumAggregator = new Aggregator<int, int>((total, next) => total + next); 3: 4: // creates an aggregator (using static method) that returns the max of previous result and next 5: var maxAggregator = new Aggregator<int, int>(Math.Max); So, if we were timing the response time of a web method every time it was called, we could pass that response time to both of these aggregators to get an idea of the total time spent in that web method, and the max time spent in any one call to the web method: 1: // total will be 13 and max 13 2: int responseTime = 13; 3: sumAggregator.Aggregate(responseTime); 4: maxAggregator.Aggregate(responseTime); 5: 6: // total will be 20 and max still 13 7: responseTime = 7; 8: sumAggregator.Aggregate(responseTime); 9: maxAggregator.Aggregate(responseTime); 10: 11: // total will be 40 and max now 20 12: responseTime = 20; 13: sumAggregator.Aggregate(responseTime); 14: maxAggregator.Aggregate(responseTime); The Func delegate family is useful for making generic algorithms and classes, and in particular allows the caller of the method or user of the class to specify a function to be performed in order to generate a result. What is the result of a Func delegate chain? If you remember, we said earlier that you can assign multiple methods to a delegate by using the += operator to chain them. So how does this affect delegates such as Func that return a value, when applied to something like the code below? 1: Func<int, int, int> combo = null; 2: 3: // What if we wanted to aggregate the sum and max together? 4: combo += (total, next) => total + next; 5: combo += Math.Max; 6: 7: // what is the result? 8: var comboAggregator = new Aggregator<int, int>(combo); Well, in .NET if you chain multiple methods in a delegate, they will all get invoked, but the result of the delegate is the result of the last method invoked in the chain. Thus, this aggregator would always result in the Math.Max() result. The other chained method (the sum) gets executed first, but it’s result is thrown away: 1: // result is 13 2: int responseTime = 13; 3: comboAggregator.Aggregate(responseTime); 4: 5: // result is still 13 6: responseTime = 7; 7: comboAggregator.Aggregate(responseTime); 8: 9: // result is now 20 10: responseTime = 20; 11: comboAggregator.Aggregate(responseTime); So remember, you can chain multiple Func (or other delegates that return values) together, but if you do so you will only get the last executed result. Func delegates and co-variance/contra-variance in .NET 4.0 Just like the Action delegate, as of .NET 4.0, the Func delegate family is contra-variant on its arguments. In addition, it is co-variant on its return type. To support this, in .NET 4.0 the signatures of the Func delegates changed to: Func<out TResult> – matches a method that takes no arguments, and returns value of type TResult (or a more derived type). Func<in T, out TResult> – matches a method that takes an argument of type T (or a less derived type), and returns value of type TResult(or a more derived type). Func<in T1, in T2, out TResult> – matches a method that takes arguments of type T1 and T2 (or less derived types), and returns value of type TResult (or a more derived type). Func<in T1, in T2, …, out TResult> – and so on up to 16 arguments, and returns value of type TResult (or a more derived type). Notice the addition of the in and out keywords before each of the generic type placeholders. As we saw last week, the in keyword is used to specify that a generic type can be contra-variant -- it can match the given type or a type that is less derived. However, the out keyword, is used to specify that a generic type can be co-variant -- it can match the given type or a type that is more derived. On contra-variance, if you are saying you need an function that will accept a string, you can just as easily give it an function that accepts an object. In other words, if you say “give me an function that will process dogs”, I could pass you a method that will process any animal, because all dogs are animals. On the co-variance side, if you are saying you need a function that returns an object, you can just as easily pass it a function that returns a string because any string returned from the given method can be accepted by a delegate expecting an object result, since string is more derived. Once again, in other words, if you say “give me a method that creates an animal”, I can pass you a method that will create a dog, because all dogs are animals. It really all makes sense, you can pass a more specific thing to a less specific parameter, and you can return a more specific thing as a less specific result. In other words, pay attention to the direction the item travels (parameters go in, results come out). Keeping that in mind, you can always pass more specific things in and return more specific things out. For example, in the code below, we have a method that takes a Func<object> to generate an object, but we can pass it a Func<string> because the return type of object can obviously accept a return value of string as well: 1: // since Func<object> is co-variant, this will access Func<string>, etc... 2: public static string Sequence(int count, Func<object> generator) 3: { 4: var builder = new StringBuilder(); 5: 6: for (int i=0; i<count; i++) 7: { 8: object value = generator(); 9: builder.Append(value); 10: } 11: 12: return builder.ToString(); 13: } Even though the method above takes a Func<object>, we can pass a Func<string> because the TResult type placeholder is co-variant and accepts types that are more derived as well: 1: // delegate that's typed to return string. 2: Func<string> stringGenerator = () => DateTime.Now.ToString(); 3: 4: // This will work in .NET 4.0, but not in previous versions 5: Sequence(100, stringGenerator); Previous versions of .NET implemented some forms of co-variance and contra-variance before, but .NET 4.0 goes one step further and allows you to pass or assign an Func<A, BResult> to a Func<Y, ZResult> as long as A is less derived (or same) as Y, and BResult is more derived (or same) as ZResult. Sidebar: The Func and the Predicate A method that takes one argument and returns a bool is generally thought of as a predicate. Predicates are used to examine an item and determine whether that item satisfies a particular condition. Predicates are typically unary, but you may also have binary and other predicates as well. Predicates are often used to filter results, such as in the LINQ Where() extension method: 1: var numbers = new[] { 1, 2, 4, 13, 8, 10, 27 }; 2: 3: // call Where() using a predicate which determines if the number is even 4: var evens = numbers.Where(num => num % 2 == 0); As of .NET 3.5, predicates are typically represented as Func<T, bool> where T is the type of the item to examine. Previous to .NET 3.5, there was a Predicate<T> type that tended to be used (which we’ll discuss next week) and is still supported, but most developers recommend using Func<T, bool> now, as it prevents confusion with overloads that accept unary predicates and binary predicates, etc.: 1: // this seems more confusing as an overload set, because of Predicate vs Func 2: public static SomeMethod(Predicate<int> unaryPredicate) { } 3: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } 4: 5: // this seems more consistent as an overload set, since just uses Func 6: public static SomeMethod(Func<int, bool> unaryPredicate) { } 7: public static SomeMethod(Func<int, int, bool> binaryPredicate) { } Also, even though Predicate<T> and Func<T, bool> match the same signatures, they are separate types! Thus you cannot assign a Predicate<T> instance to a Func<T, bool> instance and vice versa: 1: // the same method, lambda expression, etc can be assigned to both 2: Predicate<int> isEven = i => (i % 2) == 0; 3: Func<int, bool> alsoIsEven = i => (i % 2) == 0; 4: 5: // but the delegate instances cannot be directly assigned, strongly typed! 6: // ERROR: cannot convert type... 7: isEven = alsoIsEven; 8: 9: // however, you can assign by wrapping in a new instance: 10: isEven = new Predicate<int>(alsoIsEven); 11: alsoIsEven = new Func<int, bool>(isEven); So, the general advice that seems to come from most developers is that Predicate<T> is still supported, but we should use Func<T, bool> for consistency in .NET 3.5 and above. Sidebar: Func as a Generator for Unit Testing One area of difficulty in unit testing can be unit testing code that is based on time of day. We’d still want to unit test our code to make sure the logic is accurate, but we don’t want the results of our unit tests to be dependent on the time they are run. One way (of many) around this is to create an internal generator that will produce the “current” time of day. This would default to returning result from DateTime.Now (or some other method), but we could inject specific times for our unit testing. Generators are typically methods that return (generate) a value for use in a class/method. For example, say we are creating a CacheItem<T> class that represents an item in the cache, and we want to make sure the item shows as expired if the age is more than 30 seconds. Such a class could look like: 1: // responsible for maintaining an item of type T in the cache 2: public sealed class CacheItem<T> 3: { 4: // helper method that returns the current time 5: private static Func<DateTime> _timeGenerator = () => DateTime.Now; 6: 7: // allows internal access to the time generator 8: internal static Func<DateTime> TimeGenerator 9: { 10: get { return _timeGenerator; } 11: set { _timeGenerator = value; } 12: } 13: 14: // time the item was cached 15: public DateTime CachedTime { get; private set; } 16: 17: // the item cached 18: public T Value { get; private set; } 19: 20: // item is expired if older than 30 seconds 21: public bool IsExpired 22: { 23: get { return _timeGenerator() - CachedTime > TimeSpan.FromSeconds(30.0); } 24: } 25: 26: // creates the new cached item, setting cached time to "current" time 27: public CacheItem(T value) 28: { 29: Value = value; 30: CachedTime = _timeGenerator(); 31: } 32: } Then, we can use this construct to unit test our CacheItem<T> without any time dependencies: 1: var baseTime = DateTime.Now; 2: 3: // start with current time stored above (so doesn't drift) 4: CacheItem<int>.TimeGenerator = () => baseTime; 5: 6: var target = new CacheItem<int>(13); 7: 8: // now add 15 seconds, should still be non-expired 9: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(15); 10: 11: Assert.IsFalse(target.IsExpired); 12: 13: // now add 31 seconds, should now be expired 14: CacheItem<int>.TimeGenerator = () => baseTime.AddSeconds(31); 15: 16: Assert.IsTrue(target.IsExpired); Now we can unit test for 1 second before, 1 second after, 1 millisecond before, 1 day after, etc. Func delegates can be a handy tool for this type of value generation to support more testable code. Summary Generic delegates give us a lot of power to make truly generic algorithms and classes. The Func family of delegates is a great way to be able to specify functions to calculate a result based on 0-16 arguments. Stay tuned in the weeks that follow for other generic delegates in the .NET Framework! Tweet Technorati Tags: .NET, C#, CSharp, Little Wonders, Generics, Func, Delegates

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Reinventing the Paged IEnumerable, Weigert Style!

- by adweigert

I am pretty sure someone else has done this, I've seen variations as PagedList<T>, but this is my style of a paged IEnumerable collection. I just store a reference to the collection and generate the paged data when the enumerator is needed, so you could technically add to a list that I'm referencing and the properties and results would be adjusted accordingly. I don't mind reinventing the wheel when I can add some of my own personal flare ... // Extension method for easy use public static PagedEnumerable AsPaged(this IEnumerable collection, int currentPage = 1, int pageSize = 0) { Contract.Requires(collection != null); Contract.Assume(currentPage >= 1); Contract.Assume(pageSize >= 0); return new PagedEnumerable(collection, currentPage, pageSize); } public class PagedEnumerable : IEnumerable { public PagedEnumerable(IEnumerable collection, int currentPage = 1, int pageSize = 0) { Contract.Requires(collection != null); Contract.Assume(currentPage >= 1); Contract.Assume(pageSize >= 0); this.collection = collection; this.PageSize = pageSize; this.CurrentPage = currentPage; } IEnumerable collection; int currentPage; public int CurrentPage { get { if (this.currentPage > this.TotalPages) { return this.TotalPages; } return this.currentPage; } set { if (value < 1) { this.currentPage = 1; } else if (value > this.TotalPages) { this.currentPage = this.TotalPages; } else { this.currentPage = value; } } } int pageSize; public int PageSize { get { if (this.pageSize == 0) { return this.collection.Count(); } return this.pageSize; } set { this.pageSize = (value < 0) ? 0 : value; } } public int TotalPages { get { return (int)Math.Ceiling(this.collection.Count() / (double)this.PageSize); } } public IEnumerator GetEnumerator() { var pageSize = this.PageSize; var currentPage = this.CurrentPage; var startCount = (currentPage - 1) * pageSize; return this.collection.Skip(startCount).Take(pageSize).GetEnumerator(); } IEnumerator IEnumerable.GetEnumerator() { return this.GetEnumerator(); } }

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Adding complexity to remove duplicate code

- by Phil

I have several classes that all inherit from a generic base class. The base class contains a collection of several objects of type T. Each child class needs to be able to calculate interpolated values from the collection of objects, but since the child classes use different types, the calculation varies a tiny bit from class to class. So far I have copy/pasted my code from class to class and made minor modifications to each. But now I am trying to remove the duplicated code and replace it with one generic interpolation method in my base class. However that is proving to be very difficult, and all the solutions I have thought of seem way too complex. I am starting to think the DRY principle does not apply as much in this kind of situation, but that sounds like blasphemy. How much complexity is too much when trying to remove code duplication? EDIT: The best solution I can come up with goes something like this: Base Class: protected T GetInterpolated(int frame) { var index = SortedFrames.BinarySearch(frame); if (index >= 0) return Data[index]; index = ~index; if (index == 0) return Data[index]; if (index >= Data.Count) return Data[Data.Count - 1]; return GetInterpolatedItem(frame, Data[index - 1], Data[index]); } protected abstract T GetInterpolatedItem(int frame, T lower, T upper); Child class A: public IGpsCoordinate GetInterpolatedCoord(int frame) { ReadData(); return GetInterpolated(frame); } protected override IGpsCoordinate GetInterpolatedItem(int frame, IGpsCoordinate lower, IGpsCoordinate upper) { double ratio = GetInterpolationRatio(frame, lower.Frame, upper.Frame); var x = GetInterpolatedValue(lower.X, upper.X, ratio); var y = GetInterpolatedValue(lower.Y, upper.Y, ratio); var z = GetInterpolatedValue(lower.Z, upper.Z, ratio); return new GpsCoordinate(frame, x, y, z); } Child class B: public double GetMph(int frame) { ReadData(); return GetInterpolated(frame).MilesPerHour; } protected override ISpeed GetInterpolatedItem(int frame, ISpeed lower, ISpeed upper) { var ratio = GetInterpolationRatio(frame, lower.Frame, upper.Frame); var mph = GetInterpolatedValue(lower.MilesPerHour, upper.MilesPerHour, ratio); return new Speed(frame, mph); }

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SpringMvc java.lang.NullPointerException When Posting Form To Server [closed]

- by dev_darin

I have a form with a user name field on it when i tab out of the field i use a RESTFUL Web Service that makes a call to a handler method in the controller. The method makes a call to a DAO class that checks the database if the user name exists. This works fine, however when the form is posted to the server i call the same exact function i would call in the handler method however i get a java.lang.NullPointerException when it accesses the class that makes a call to the DAO object. So it does not even access the DAO object the second time. I have exception handlers around the calls in all my classes that makes calls. Any ideas as to whats happening here why i would get the java.lang.NullPointerException the second time the function is called.Does this have anything to do with Spring instantiating DAO classes using a Singleton method or something to that effect? What can be done to resolve this? This is what happens the First Time The Method is called using the Web Service(this is suppose to happen): 13011 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - Inside jdbcOfficersDAO 13031 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL query 13034 [http-8084-2] DEBUG org.springframework.jdbc.core.JdbcTemplate - Executing prepared SQL statement [SELECT userName FROM crimetrack.tblofficers WHERE userName = ?] 13071 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Fetching JDBC Connection from DataSource 13496 [http-8084-2] DEBUG org.springframework.jdbc.core.StatementCreatorUtils - Setting SQL statement parameter value: column index 1, parameter value [adminz], value class [java.lang.String], SQL type unknown 13534 [http-8084-2] DEBUG org.springframework.jdbc.datasource.DataSourceUtils - Returning JDBC Connection to DataSource 13537 [http-8084-2] INFO com.crimetrack.jdbc.JdbcOfficersDAO - No username was found in exception 13537 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz does NOT exist The Second time When The Form Is 'Post' and a validation method handles the form and calls the same method the web service would call: 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 17199 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - Inside Do UserNameExist about to validate with username : adminz 17199 [http-8084-2] INFO com.crimetrack.service.ValidateUserNameManager - UserName :adminz EXCEPTION OCCURED java.lang.NullPointerException ValidateUserNameManager.java public class ValidateUserNameManager implements ValidateUserNameIFace { private OfficersDAO officerDao; private final Logger logger = Logger.getLogger(getClass()); public boolean DoesUserNameExist(String userName) throws Exception { logger.info("Inside Do UserNameExist about to validate with username : " + userName); try{ if(officerDao.OfficerExist(userName) == true){ logger.info("UserName :" + userName + " does exist"); return true; }else{ logger.info("UserName :" + userName + " does NOT exist"); return false; } }catch(Exception e){ logger.info("UserName :" + userName + " EXCEPTION OCCURED " + e.toString()); return false; } } /** * @return the officerDao */ public OfficersDAO getOfficerDao() { return officerDao; } /** * @param officerdao the officerDao to set */ public void setOfficerDao(OfficersDAO officerDao) { this.officerDao = officerDao; } } JdbcOfficersDAO.java public boolean OfficerExist(String userName){ String dbUserName; try{ logger.info("Inside jdbcOfficersDAO"); String sql = "SELECT userName FROM crimetrack.tblofficers WHERE userName = ?"; try{ dbUserName = (String)getJdbcTemplate().queryForObject(sql, new Object[]{userName},String.class); logger.info("Just Returned from database"); }catch(Exception e){ logger.info("No username was found in exception"); return false; } if(dbUserName == null){ logger.info("Database did not find any matching records"); } logger.info("after JdbcTemplate"); if (dbUserName.equals(userName)) { logger.info("User Name Exists"); return true; }else{ logger.info("User Name Does NOT Exists"); return false; } }catch(Exception e){ logger.info("Exception Message in JdbcOfficersDAO is "+e.getMessage()); return false; } } OfficerRegistrationValidation.java public class OfficerRegistrationValidation implements Validator{ private final Logger logger = Logger.getLogger(getClass()); private ValidateUserNameManager validateUserNameManager; public boolean supports(Class<?> clazz) { return Officers.class.equals(clazz); } public void validate(Object target, Errors errors) { Officers officer = (Officers) target; if (officer.getUserName() == null){ errors.rejectValue("userName", "userName.required"); }else{ String userName = officer.getUserName(); logger.info("UserName is not null so going to check if its valid for :" + userName); try { logger.info("User Name in try.....catch block is " + userName); if (validateUserNameManager.DoesUserNameExist(userName)== true){ errors.rejectValue("userName", "userName.exist"); } } catch (Exception e) { logger.info("Error Occured When validating UserName"); errors.rejectValue("userName", "userName.error"); } } if(officer.getPassword()== null){ errors.rejectValue("password", "password.required"); } if(officer.getPassword2()== null){ errors.rejectValue("password2", "password2.required"); } if(officer.getfName() == null){ errors.rejectValue("fName","fName.required"); } if(officer.getlName() == null){ errors.rejectValue("lName", "lName.required"); } if (officer.getoName() == null){ errors.rejectValue("oName", "oName.required"); } if (officer.getEmailAdd() == null){ errors.rejectValue("emailAdd", "emailAdd.required"); } if (officer.getDob() == null){ errors.rejectValue("dob", "dob.required"); } if (officer.getGenderId().equals("A")){ errors.rejectValue("genderId","genderId.required"); } if(officer.getDivisionNo() == 1){ errors.rejectValue("divisionNo", "divisionNo.required"); } if(officer.getPositionId() == 1){ errors.rejectValue("positionId", "positionId.required"); } if (officer.getStartDate() == null){ errors.rejectValue("startDate","startDate.required"); } if(officer.getEndDate() == null){ errors.rejectValue("endDate","endDate.required"); } logger.info("The Gender ID is " + officer.getGenderId().toString()); if(officer.getPhoneNo() == null){ errors.rejectValue("phoneNo", "phoneNo.required"); } } /** * @return the validateUserNameManager */ public ValidateUserNameManager getValidateUserNameManager() { return validateUserNameManager; } /** * @param validateUserNameManager the validateUserNameManager to set */ public void setValidateUserNameManager( ValidateUserNameManager validateUserNameManager) { this.validateUserNameManager = validateUserNameManager; } } Update Error Log using Logger.Error("Message", e): 39024 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - UserName is not null so going to check if its valid for :adminz 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - User Name in try.....catch block is adminz 39025 [http-8084-2] ERROR com.crimetrack.service.OfficerRegistrationValidation - Message java.lang.NullPointerException at com.crimetrack.service.OfficerRegistrationValidation.validate(OfficerRegistrationValidation.java:47) at org.springframework.validation.DataBinder.validate(DataBinder.java:725) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.doBind(HandlerMethodInvoker.java:815) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.resolveHandlerArguments(HandlerMethodInvoker.java:367) at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:171) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:436) at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:424) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:923) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:852) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:882) at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:789) at javax.servlet.http.HttpServlet.service(HttpServlet.java:637) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:859) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:602) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Unknown Source) 39025 [http-8084-2] INFO com.crimetrack.service.OfficerRegistrationValidation - Error Occured When validating UserName

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What's the best way to expose a Model object in a ViewModel?

- by Angel

In a WPF MVVM application, I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel. Instead of creating separate VM properties, I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy class: public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel: public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM. I know this will cause a strong dependency. So: What's the best way to expose a Model object in a ViewModel? What's the best way to use DataService in VM?

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MVVM- Expose Model object in ViewModel

- by Angel

I have a wpf MVVM application , I exposed my model object into my viewModel by creating an instance of Model class (which cause dependency) into ViewModel , and instead of creating seperate VM properties , I wrap the Model properties inside my ViewModel Property. My model is just an entity framework generated proxy classes. Here is my Model class : public partial class TblProduct { public TblProduct() { this.TblPurchaseDetails = new HashSet<TblPurchaseDetail>(); this.TblPurchaseOrderDetails = new HashSet<TblPurchaseOrderDetail>(); this.TblSalesInvoiceDetails = new HashSet<TblSalesInvoiceDetail>(); this.TblSalesOrderDetails = new HashSet<TblSalesOrderDetail>(); } public int ProductId { get; set; } public string ProductCode { get; set; } public string ProductName { get; set; } public int CategoryId { get; set; } public string Color { get; set; } public Nullable<decimal> PurchaseRate { get; set; } public Nullable<decimal> SalesRate { get; set; } public string ImagePath { get; set; } public bool IsActive { get; set; } public virtual TblCompany TblCompany { get; set; } public virtual TblProductCategory TblProductCategory { get; set; } public virtual TblUser TblUser { get; set; } public virtual ICollection<TblPurchaseDetail> TblPurchaseDetails { get; set; } public virtual ICollection<TblPurchaseOrderDetail> TblPurchaseOrderDetails { get; set; } public virtual ICollection<TblSalesInvoiceDetail> TblSalesInvoiceDetails { get; set; } public virtual ICollection<TblSalesOrderDetail> TblSalesOrderDetails { get; set; } } Here is my ViewModel , public class ProductViewModel : WorkspaceViewModel { #region Constructor public ProductViewModel() { StartApp(); } #endregion //Constructor #region Properties private IProductDataService _dataService; public IProductDataService DataService { get { if (_dataService == null) { if (IsInDesignMode) { _dataService = new ProductDataServiceMock(); } else { _dataService = new ProductDataService(); } } return _dataService; } } //Get and set Model object private TblProduct _product; public TblProduct Product { get { return _product ?? (_product = new TblProduct()); } set { _product = value; } } #region Public Properties public int ProductId { get { return Product.ProductId; } set { if (Product.ProductId == value) { return; } Product.ProductId = value; RaisePropertyChanged("ProductId"); } } public string ProductName { get { return Product.ProductName; } set { if (Product.ProductName == value) { return; } Product.ProductName = value; RaisePropertyChanged(() => ProductName); } } private ObservableCollection<TblProduct> _productRecords; public ObservableCollection<TblProduct> ProductRecords { get { return _productRecords; } set { _productRecords = value; RaisePropertyChanged("ProductRecords"); } } //Selected Product private TblProduct _selectedProduct; public TblProduct SelectedProduct { get { return _selectedProduct; } set { _selectedProduct = value; if (_selectedProduct != null) { this.ProductId = _selectedProduct.ProductId; this.ProductCode = _selectedProduct.ProductCode; } RaisePropertyChanged("SelectedProduct"); } } #endregion //Public Properties #endregion // Properties #region Commands private ICommand _newCommand; public ICommand NewCommand { get { if (_newCommand == null) { _newCommand = new RelayCommand(() => ResetAll()); } return _newCommand; } } private ICommand _saveCommand; public ICommand SaveCommand { get { if (_saveCommand == null) { _saveCommand = new RelayCommand(() => Save()); } return _saveCommand; } } private ICommand _deleteCommand; public ICommand DeleteCommand { get { if (_deleteCommand == null) { _deleteCommand = new RelayCommand(() => Delete()); } return _deleteCommand; } } #endregion //Commands #region Methods private void StartApp() { LoadProductCollection(); } private void LoadProductCollection() { var q = DataService.GetAllProducts(); this.ProductRecords = new ObservableCollection<TblProduct>(q); } private void Save() { if (SelectedOperateMode == OperateModeEnum.OperateMode.New) { //Pass the Model object into Dataservice for save DataService.SaveProduct(this.Product); } else if (SelectedOperateMode == OperateModeEnum.OperateMode.Edit) { //Pass the Model object into Dataservice for Update DataService.UpdateProduct(this.Product); } ResetAll(); LoadProductCollection(); } #endregion //Methods } Here is my Service class: class ProductDataService:IProductDataService { /// <summary> /// Context object of Entity Framework model /// </summary> private MaizeEntities Context { get; set; } public ProductDataService() { Context = new MaizeEntities(); } public IEnumerable<TblProduct> GetAllProducts() { using(var context=new R_MaizeEntities()) { var q = from p in context.TblProducts where p.IsDel == false select p; return new ObservableCollection<TblProduct>(q); } } public void SaveProduct(TblProduct _product) { using(var context=new R_MaizeEntities()) { _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.TblProducts.Add(_product); context.SaveChanges(); } } public void UpdateProduct(TblProduct _product) { using (var context = new R_MaizeEntities()) { context.TblProducts.Attach(_product); context.Entry(_product).State = EntityState.Modified; _product.LastModUserId = GlobalObjects.LoggedUserID; _product.LastModDttm = DateTime.Now; _product.CompanyId = GlobalObjects.CompanyID; context.SaveChanges(); } } public void DeleteProduct(int _productId) { using (var context = new R_MaizeEntities()) { var product = (from c in context.TblProducts where c.ProductId == _productId select c).First(); product.LastModUserId = GlobalObjects.LoggedUserID; product.LastModDttm = DateTime.Now; product.IsDel = true; context.SaveChanges(); } } } I exposed my model object in my viewModel by creating an instance of it using new keyword, also I instantiated my DataService class in VM, I know this will cause a strong dependency. So , 1- Whats the best way to expose Model object in ViewModel ? 2- Whats the best way to use DataService in VM ?

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