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• A Taxonomy of Numerical Methods v1

  - by JoshReuben

  Numerical Analysis – When, What, (but not how) Once you understand the Math & know C++, Numerical Methods are basically blocks of iterative & conditional math code. I found the real trick was seeing the forest for the trees – knowing which method to use for which situation. Its pretty easy to get lost in the details – so I’ve tried to organize these methods in a way that I can quickly look this up. I’ve included links to detailed explanations and to C++ code examples. I’ve tried to classify Numerical methods in the following broad categories: Solving Systems of Linear Equations Solving Non-Linear Equations Iteratively Interpolation Curve Fitting Optimization Numerical Differentiation & Integration Solving ODEs Boundary Problems Solving EigenValue problems Enjoy – I did ! Solving Systems of Linear Equations Overview Solve sets of algebraic equations with x unknowns The set is commonly in matrix form Gauss-Jordan Elimination http://en.wikipedia.org/wiki/Gauss%E2%80%93Jordan_elimination C++: http://www.codekeep.net/snippets/623f1923-e03c-4636-8c92-c9dc7aa0d3c0.aspx Produces solution of the equations & the coefficient matrix Efficient, stable 2 steps: · Forward Elimination – matrix decomposition: reduce set to triangular form (0s below the diagonal) or row echelon form. If degenerate, then there is no solution · Backward Elimination –write the original matrix as the product of ints inverse matrix & its reduced row-echelon matrix à reduce set to row canonical form & use back-substitution to find the solution to the set Elementary ops for matrix decomposition: · Row multiplication · Row switching · Add multiples of rows to other rows Use pivoting to ensure rows are ordered for achieving triangular form LU Decomposition http://en.wikipedia.org/wiki/LU_decomposition C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-lu-decomposition-for-solving.html Represent the matrix as a product of lower & upper triangular matrices A modified version of GJ Elimination Advantage – can easily apply forward & backward elimination to solve triangular matrices Techniques: · Doolittle Method – sets the L matrix diagonal to unity · Crout Method - sets the U matrix diagonal to unity Note: both the L & U matrices share the same unity diagonal & can be stored compactly in the same matrix Gauss-Seidel Iteration http://en.wikipedia.org/wiki/Gauss%E2%80%93Seidel_method C++: http://www.nr.com/forum/showthread.php?t=722 Transform the linear set of equations into a single equation & then use numerical integration (as integration formulas have Sums, it is implemented iteratively). an optimization of Gauss-Jacobi: 1.5 times faster, requires 0.25 iterations to achieve the same tolerance Solving Non-Linear Equations Iteratively find roots of polynomials – there may be 0, 1 or n solutions for an n order polynomial use iterative techniques Iterative methods · used when there are no known analytical techniques · Requires set functions to be continuous & differentiable · Requires an initial seed value – choice is critical to convergence à conduct multiple runs with different starting points & then select best result · Systematic - iterate until diminishing returns, tolerance or max iteration conditions are met · bracketing techniques will always yield convergent solutions, non-bracketing methods may fail to converge Incremental method if a nonlinear function has opposite signs at 2 ends of a small interval x1 & x2, then there is likely to be a solution in their interval – solutions are detected by evaluating a function over interval steps, for a change in sign, adjusting the step size dynamically. Limitations – can miss closely spaced solutions in large intervals, cannot detect degenerate (coinciding) solutions, limited to functions that cross the x-axis, gives false positives for singularities Fixed point method http://en.wikipedia.org/wiki/Fixed-point_iteration C++: http://books.google.co.il/books?id=weYj75E_t6MC&pg=PA79&lpg=PA79&dq=fixed+point+method++c%2B%2B&source=bl&ots=LQ-5P_taoC&sig=lENUUIYBK53tZtTwNfHLy5PEWDk&hl=en&sa=X&ei=wezDUPW1J5DptQaMsIHQCw&redir_esc=y#v=onepage&q=fixed%20point%20method%20%20c%2B%2B&f=false Algebraically rearrange a solution to isolate a variable then apply incremental method Bisection method http://en.wikipedia.org/wiki/Bisection_method C++: http://numericalcomputing.wordpress.com/category/algorithms/ Bracketed - Select an initial interval, keep bisecting it ad midpoint into sub-intervals and then apply incremental method on smaller & smaller intervals – zoom in Adv: unaffected by function gradient à reliable Disadv: slow convergence False Position Method http://en.wikipedia.org/wiki/False_position_method C++: http://www.dreamincode.net/forums/topic/126100-bisection-and-false-position-methods/ Bracketed - Select an initial interval , & use the relative value of function at interval end points to select next sub-intervals (estimate how far between the end points the solution might be & subdivide based on this) Newton-Raphson method http://en.wikipedia.org/wiki/Newton's_method C++: http://www-users.cselabs.umn.edu/classes/Summer-2012/csci1113/index.php?page=./newt3 Also known as Newton's method Convenient, efficient Not bracketed – only a single initial guess is required to start iteration – requires an analytical expression for the first derivative of the function as input. Evaluates the function & its derivative at each step. Can be extended to the Newton MutiRoot method for solving multiple roots Can be easily applied to an of n-coupled set of non-linear equations – conduct a Taylor Series expansion of a function, dropping terms of order n, rewrite as a Jacobian matrix of PDs & convert to simultaneous linear equations !!! Secant Method http://en.wikipedia.org/wiki/Secant_method C++: http://forum.vcoderz.com/showthread.php?p=205230 Unlike N-R, can estimate first derivative from an initial interval (does not require root to be bracketed) instead of inputting it Since derivative is approximated, may converge slower. Is fast in practice as it does not have to evaluate the derivative at each step. Similar implementation to False Positive method Birge-Vieta Method http://mat.iitm.ac.in/home/sryedida/public_html/caimna/transcendental/polynomial%20methods/bv%20method.html C++: http://books.google.co.il/books?id=cL1boM2uyQwC&pg=SA3-PA51&lpg=SA3-PA51&dq=Birge-Vieta+Method+c%2B%2B&source=bl&ots=QZmnDTK3rC&sig=BPNcHHbpR_DKVoZXrLi4nVXD-gg&hl=en&sa=X&ei=R-_DUK2iNIjzsgbE5ID4Dg&redir_esc=y#v=onepage&q=Birge-Vieta%20Method%20c%2B%2B&f=false combines Horner's method of polynomial evaluation (transforming into lesser degree polynomials that are more computationally efficient to process) with Newton-Raphson to provide a computational speed-up Interpolation Overview Construct new data points for as close as possible fit within range of a discrete set of known points (that were obtained via sampling, experimentation) Use Taylor Series Expansion of a function f(x) around a specific value for x Linear Interpolation http://en.wikipedia.org/wiki/Linear_interpolation C++: http://www.hamaluik.com/?p=289 Straight line between 2 points à concatenate interpolants between each pair of data points Bilinear Interpolation http://en.wikipedia.org/wiki/Bilinear_interpolation C++: http://supercomputingblog.com/graphics/coding-bilinear-interpolation/2/ Extension of the linear function for interpolating functions of 2 variables – perform linear interpolation first in 1 direction, then in another. Used in image processing – e.g. texture mapping filter. Uses 4 vertices to interpolate a value within a unit cell. Lagrange Interpolation http://en.wikipedia.org/wiki/Lagrange_polynomial C++: http://www.codecogs.com/code/maths/approximation/interpolation/lagrange.php For polynomials Requires recomputation for all terms for each distinct x value – can only be applied for small number of nodes Numerically unstable Barycentric Interpolation http://epubs.siam.org/doi/pdf/10.1137/S0036144502417715 C++: http://www.gamedev.net/topic/621445-barycentric-coordinates-c-code-check/ Rearrange the terms in the equation of the Legrange interpolation by defining weight functions that are independent of the interpolated value of x Newton Divided Difference Interpolation http://en.wikipedia.org/wiki/Newton_polynomial C++: http://jee-appy.blogspot.co.il/2011/12/newton-divided-difference-interpolation.html Hermite Divided Differences: Interpolation polynomial approximation for a given set of data points in the NR form - divided differences are used to approximately calculate the various differences. For a given set of 3 data points , fit a quadratic interpolant through the data Bracketed functions allow Newton divided differences to be calculated recursively Difference table Cubic Spline Interpolation http://en.wikipedia.org/wiki/Spline_interpolation C++: https://www.marcusbannerman.co.uk/index.php/home/latestarticles/42-articles/96-cubic-spline-class.html Spline is a piecewise polynomial Provides smoothness – for interpolations with significantly varying data Use weighted coefficients to bend the function to be smooth & its 1st & 2nd derivatives are continuous through the edge points in the interval Curve Fitting A generalization of interpolating whereby given data points may contain noise à the curve does not necessarily pass through all the points Least Squares Fit http://en.wikipedia.org/wiki/Least_squares C++: http://www.ccas.ru/mmes/educat/lab04k/02/least-squares.c Residual – difference between observed value & expected value Model function is often chosen as a linear combination of the specified functions Determines: A) The model instance in which the sum of squared residuals has the least value B) param values for which model best fits data Straight Line Fit Linear correlation between independent variable and dependent variable Linear Regression http://en.wikipedia.org/wiki/Linear_regression C++: http://www.oocities.org/david_swaim/cpp/linregc.htm Special case of statistically exact extrapolation Leverage least squares Given a basis function, the sum of the residuals is determined and the corresponding gradient equation is expressed as a set of normal linear equations in matrix form that can be solved (e.g. using LU Decomposition) Can be weighted - Drop the assumption that all errors have the same significance –-> confidence of accuracy is different for each data point. Fit the function closer to points with higher weights Polynomial Fit - use a polynomial basis function Moving Average http://en.wikipedia.org/wiki/Moving_average C++: http://www.codeproject.com/Articles/17860/A-Simple-Moving-Average-Algorithm Used for smoothing (cancel fluctuations to highlight longer-term trends & cycles), time series data analysis, signal processing filters Replace each data point with average of neighbors. Can be simple (SMA), weighted (WMA), exponential (EMA). Lags behind latest data points – extra weight can be given to more recent data points. Weights can decrease arithmetically or exponentially according to distance from point. Parameters: smoothing factor, period, weight basis Optimization Overview Given function with multiple variables, find Min (or max by minimizing –f(x)) Iterative approach Efficient, but not necessarily reliable Conditions: noisy data, constraints, non-linear models Detection via sign of first derivative - Derivative of saddle points will be 0 Local minima Bisection method Similar method for finding a root for a non-linear equation Start with an interval that contains a minimum Golden Search method http://en.wikipedia.org/wiki/Golden_section_search C++: http://www.codecogs.com/code/maths/optimization/golden.php Bisect intervals according to golden ratio 0.618.. Achieves reduction by evaluating a single function instead of 2 Newton-Raphson Method Brent method http://en.wikipedia.org/wiki/Brent's_method C++: http://people.sc.fsu.edu/~jburkardt/cpp_src/brent/brent.cpp Based on quadratic or parabolic interpolation – if the function is smooth & parabolic near to the minimum, then a parabola fitted through any 3 points should approximate the minima – fails when the 3 points are collinear , in which case the denominator is 0 Simplex Method http://en.wikipedia.org/wiki/Simplex_algorithm C++: http://www.codeguru.com/cpp/article.php/c17505/Simplex-Optimization-Algorithm-and-Implemetation-in-C-Programming.htm Find the global minima of any multi-variable function Direct search – no derivatives required At each step it maintains a non-degenerative simplex – a convex hull of n+1 vertices. Obtains the minimum for a function with n variables by evaluating the function at n-1 points, iteratively replacing the point of worst result with the point of best result, shrinking the multidimensional simplex around the best point. Point replacement involves expanding & contracting the simplex near the worst value point to determine a better replacement point Oscillation can be avoided by choosing the 2nd worst result Restart if it gets stuck Parameters: contraction & expansion factors Simulated Annealing http://en.wikipedia.org/wiki/Simulated_annealing C++: http://code.google.com/p/cppsimulatedannealing/ Analogy to heating & cooling metal to strengthen its structure Stochastic method – apply random permutation search for global minima - Avoid entrapment in local minima via hill climbing Heating schedule - Annealing schedule params: temperature, iterations at each temp, temperature delta Cooling schedule – can be linear, step-wise or exponential Differential Evolution http://en.wikipedia.org/wiki/Differential_evolution C++: http://www.amichel.com/de/doc/html/ More advanced stochastic methods analogous to biological processes: Genetic algorithms, evolution strategies Parallel direct search method against multiple discrete or continuous variables Initial population of variable vectors chosen randomly – if weighted difference vector of 2 vectors yields a lower objective function value then it replaces the comparison vector Many params: #parents, #variables, step size, crossover constant etc Convergence is slow – many more function evaluations than simulated annealing Numerical Differentiation Overview 2 approaches to finite difference methods: · A) approximate function via polynomial interpolation then differentiate · B) Taylor series approximation – additionally provides error estimate Finite Difference methods http://en.wikipedia.org/wiki/Finite_difference_method C++: http://www.wpi.edu/Pubs/ETD/Available/etd-051807-164436/unrestricted/EAMPADU.pdf Find differences between high order derivative values - Approximate differential equations by finite differences at evenly spaced data points Based on forward & backward Taylor series expansion of f(x) about x plus or minus multiples of delta h. Forward / backward difference - the sums of the series contains even derivatives and the difference of the series contains odd derivatives – coupled equations that can be solved. Provide an approximation of the derivative within a O(h^2) accuracy There is also central difference & extended central difference which has a O(h^4) accuracy Richardson Extrapolation http://en.wikipedia.org/wiki/Richardson_extrapolation C++: http://mathscoding.blogspot.co.il/2012/02/introduction-richardson-extrapolation.html A sequence acceleration method applied to finite differences Fast convergence, high accuracy O(h^4) Derivatives via Interpolation Cannot apply Finite Difference method to discrete data points at uneven intervals – so need to approximate the derivative of f(x) using the derivative of the interpolant via 3 point Lagrange Interpolation Note: the higher the order of the derivative, the lower the approximation precision Numerical Integration Estimate finite & infinite integrals of functions More accurate procedure than numerical differentiation Use when it is not possible to obtain an integral of a function analytically or when the function is not given, only the data points are Newton Cotes Methods http://en.wikipedia.org/wiki/Newton%E2%80%93Cotes_formulas C++: http://www.siafoo.net/snippet/324 For equally spaced data points Computationally easy – based on local interpolation of n rectangular strip areas that is piecewise fitted to a polynomial to get the sum total area Evaluate the integrand at n+1 evenly spaced points – approximate definite integral by Sum Weights are derived from Lagrange Basis polynomials Leverage Trapezoidal Rule for default 2nd formulas, Simpson 1/3 Rule for substituting 3 point formulas, Simpson 3/8 Rule for 4 point formulas. For 4 point formulas use Bodes Rule. Higher orders obtain more accurate results Trapezoidal Rule uses simple area, Simpsons Rule replaces the integrand f(x) with a quadratic polynomial p(x) that uses the same values as f(x) for its end points, but adds a midpoint Romberg Integration http://en.wikipedia.org/wiki/Romberg's_method C++: http://code.google.com/p/romberg-integration/downloads/detail?name=romberg.cpp&can=2&q= Combines trapezoidal rule with Richardson Extrapolation Evaluates the integrand at equally spaced points The integrand must have continuous derivatives Each R(n,m) extrapolation uses a higher order integrand polynomial replacement rule (zeroth starts with trapezoidal) à a lower triangular matrix set of equation coefficients where the bottom right term has the most accurate approximation. The process continues until the difference between 2 successive diagonal terms becomes sufficiently small. Gaussian Quadrature http://en.wikipedia.org/wiki/Gaussian_quadrature C++: http://www.alglib.net/integration/gaussianquadratures.php Data points are chosen to yield best possible accuracy – requires fewer evaluations Ability to handle singularities, functions that are difficult to evaluate The integrand can include a weighting function determined by a set of orthogonal polynomials. Points & weights are selected so that the integrand yields the exact integral if f(x) is a polynomial of degree <= 2n+1 Techniques (basically different weighting functions): · Gauss-Legendre Integration w(x)=1 · Gauss-Laguerre Integration w(x)=e^-x · Gauss-Hermite Integration w(x)=e^-x^2 · Gauss-Chebyshev Integration w(x)= 1 / Sqrt(1-x^2) Solving ODEs Use when high order differential equations cannot be solved analytically Evaluated under boundary conditions RK for systems – a high order differential equation can always be transformed into a coupled first order system of equations Euler method http://en.wikipedia.org/wiki/Euler_method C++: http://rosettacode.org/wiki/Euler_method First order Runge–Kutta method. Simple recursive method – given an initial value, calculate derivative deltas. Unstable & not very accurate (O(h) error) – not used in practice A first-order method - the local error (truncation error per step) is proportional to the square of the step size, and the global error (error at a given time) is proportional to the step size In evolving solution between data points xn & xn+1, only evaluates derivatives at beginning of interval xn à asymmetric at boundaries Higher order Runge Kutta http://en.wikipedia.org/wiki/Runge%E2%80%93Kutta_methods C++: http://www.dreamincode.net/code/snippet1441.htm 2nd & 4th order RK - Introduces parameterized midpoints for more symmetric solutions à accuracy at higher computational cost Adaptive RK – RK-Fehlberg – estimate the truncation at each integration step & automatically adjust the step size to keep error within prescribed limits. At each step 2 approximations are compared – if in disagreement to a specific accuracy, the step size is reduced Boundary Value Problems Where solution of differential equations are located at 2 different values of the independent variable x à more difficult, because cannot just start at point of initial value – there may not be enough starting conditions available at the end points to produce a unique solution An n-order equation will require n boundary conditions – need to determine the missing n-1 conditions which cause the given conditions at the other boundary to be satisfied Shooting Method http://en.wikipedia.org/wiki/Shooting_method C++: http://ganeshtiwaridotcomdotnp.blogspot.co.il/2009/12/c-c-code-shooting-method-for-solving.html Iteratively guess the missing values for one end & integrate, then inspect the discrepancy with the boundary values of the other end to adjust the estimate Given the starting boundary values u1 & u2 which contain the root u, solve u given the false position method (solving the differential equation as an initial value problem via 4th order RK), then use u to solve the differential equations. Finite Difference Method For linear & non-linear systems Higher order derivatives require more computational steps – some combinations for boundary conditions may not work though Improve the accuracy by increasing the number of mesh points Solving EigenValue Problems An eigenvalue can substitute a matrix when doing matrix multiplication à convert matrix multiplication into a polynomial EigenValue For a given set of equations in matrix form, determine what are the solution eigenvalue & eigenvectors Similar Matrices - have same eigenvalues. Use orthogonal similarity transforms to reduce a matrix to diagonal form from which eigenvalue(s) & eigenvectors can be computed iteratively Jacobi method http://en.wikipedia.org/wiki/Jacobi_method C++: http://people.sc.fsu.edu/~jburkardt/classes/acs2_2008/openmp/jacobi/jacobi.html Robust but Computationally intense – use for small matrices < 10x10 Power Iteration http://en.wikipedia.org/wiki/Power_iteration For any given real symmetric matrix, generate the largest single eigenvalue & its eigenvectors Simplest method – does not compute matrix decomposition à suitable for large, sparse matrices Inverse Iteration Variation of power iteration method – generates the smallest eigenvalue from the inverse matrix Rayleigh Method http://en.wikipedia.org/wiki/Rayleigh's_method_of_dimensional_analysis Variation of power iteration method Rayleigh Quotient Method Variation of inverse iteration method Matrix Tri-diagonalization Method Use householder algorithm to reduce an NxN symmetric matrix to a tridiagonal real symmetric matrix vua N-2 orthogonal transforms     Whats Next Outside of Numerical Methods there are lots of different types of algorithms that I’ve learned over the decades: Data Mining – (I covered this briefly in a previous post: http://geekswithblogs.net/JoshReuben/archive/2007/12/31/ssas-dm-algorithms.aspx ) Search & Sort Routing Problem Solving Logical Theorem Proving Planning Probabilistic Reasoning Machine Learning Solvers (eg MIP) Bioinformatics (Sequence Alignment, Protein Folding) Quant Finance (I read Wilmott’s books – interesting) Sooner or later, I’ll cover the above topics as well.

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• Use Extension method to write cleaner code

  - by Fredrik N

  This blog post will show you step by step to refactoring some code to be more readable (at least what I think). Patrik Löwnedahl gave me some of the ideas when we where talking about making code much cleaner. The following is an simple application that will have a list of movies (Normal and Transfer). The task of the application is to calculate the total sum of each movie and also display the price of each movie. class Program { enum MovieType { Normal, Transfer } static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies) { if (movie == MovieType.Normal) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } else if (movie == MovieType.Transfer) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } } } private static IEnumerable<MovieType> GetMovies() { return new List<MovieType>() { MovieType.Normal, MovieType.Transfer, MovieType.Normal }; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } In the code above I’m using an enum, a good way to add types (isn’t it ;)). I also use one foreach loop to calculate the price, the loop has a condition statement to check what kind of movie is added to the list of movies. I want to reuse the foreach only to increase performance and let it do two things (isn’t that smart of me?! ;)). First of all I can admit, I’m not a big fan of enum. Enum often results in ugly condition statements and can be hard to maintain (if a new type is added we need to check all the code in our app to see if we use the enum somewhere else). I don’t often care about pre-optimizations when it comes to write code (of course I have performance in mind). I rather prefer to use two foreach to let them do one things instead of two. So based on what I don’t like and Martin Fowler’s Refactoring catalog, I’m going to refactoring this code to what I will call a more elegant and cleaner code. First of all I’m going to use Split Loop to make sure the foreach will do one thing not two, it will results in two foreach (Don’t care about performance here, if the results will results in bad performance, you can refactoring later, but computers are so fast to day, so iterating through a list is not often so time consuming.) Note: The foreach actually do four things, will come to is later. var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies) { if (movie == MovieType.Normal) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } } foreach (var movie in movies) { if (movie == MovieType.Transfer) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } To remove the condition statement we can use the Where extension method added to the IEnumerable<T> and is located in the System.Linq namespace: foreach (var movie in movies.Where( m => m == MovieType.Normal)) { totalPriceOfNormalMovie += 2; Console.WriteLine("$2"); } foreach (var movie in movies.Where( m => m == MovieType.Transfer)) { totalPriceOfTransferMovie += 3; Console.WriteLine("$3"); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The above code will still do two things, calculate the total price, and display the price of the movie. I will not take care of it at the moment, instead I will focus on the enum and try to remove them. One way to remove enum is by using the Replace Conditional with Polymorphism. So I will create two classes, one base class called Movie, and one called MovieTransfer. The Movie class will have a property called Price, the Movie will now hold the price:   public class Movie { public virtual int Price { get { return 2; } } } public class MovieTransfer : Movie { public override int Price { get { return 3; } } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The following code has no enum and will use the new Movie classes instead: class Program { static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = 0; int totalPriceOfTransferMovie = 0; foreach (var movie in movies.Where( m => m is Movie)) { totalPriceOfNormalMovie += movie.Price; Console.WriteLine(movie.Price); } foreach (var movie in movies.Where( m => m is MovieTransfer)) { totalPriceOfTransferMovie += movie.Price; Console.WriteLine(movie.Price); } } private static IEnumerable<Movie> GetMovies() { return new List<Movie>() { new Movie(), new MovieTransfer(), new Movie() }; } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; }   If you take a look at the foreach now, you can see it still actually do two things, calculate the price and display the price. We can do some more refactoring here by using the Sum extension method to calculate the total price of the movies:   static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfNormalMovie = movies.Where(m => m is Movie) .Sum(m => m.Price); int totalPriceOfTransferMovie = movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); foreach (var movie in movies.Where( m => m is Movie)) Console.WriteLine(movie.Price); foreach (var movie in movies.Where( m => m is MovieTransfer)) Console.WriteLine(movie.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now when the Movie object will hold the price, there is no need to use two separate foreach to display the price of the movies in the list, so we can use only one instead: foreach (var movie in movies) Console.WriteLine(movie.Price); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } If we want to increase the Maintainability index we can use the Extract Method to move the Sum of the prices into two separate methods. The name of the method will explain what we are doing: static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); foreach (var movie in movies) Console.WriteLine(movie.Price); } private static int TotalPriceOfMovieTransfer(IEnumerable<Movie> movies) { return movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); } private static int TotalPriceOfMovie(IEnumerable<Movie> movies) { return movies.Where(m => m is Movie) .Sum(m => m.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now to the last thing, I love the ForEach method of the List<T>, but the IEnumerable<T> doesn’t have it, so I created my own ForEach extension, here is the code of the ForEach extension method: public static class LoopExtensions { public static void ForEach<T>(this IEnumerable<T> values, Action<T> action) { Contract.Requires(values != null); Contract.Requires(action != null); foreach (var v in values) action(v); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I will now replace the foreach by using this ForEach method: static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); movies.ForEach(m => Console.WriteLine(m.Price)); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } The ForEach on the movies will now display the price of the movie, but maybe we want to display the name of the movie etc, so we can use Extract Method by moving the lamdba expression into a method instead, and let the method explains what we are displaying: movies.ForEach(DisplayMovieInfo); private static void DisplayMovieInfo(Movie movie) { Console.WriteLine(movie.Price); } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } Now the refactoring is done! Here is the complete code:   class Program { static void Main(string[] args) { var movies = GetMovies(); int totalPriceOfMovie = TotalPriceOfMovie(movies); int totalPriceOfTransferMovie = TotalPriceOfMovieTransfer(movies); movies.ForEach(DisplayMovieInfo); } private static void DisplayMovieInfo(Movie movie) { Console.WriteLine(movie.Price); } private static int TotalPriceOfMovieTransfer(IEnumerable<Movie> movies) { return movies.Where(m => m is MovieTransfer) .Sum(m => m.Price); } private static int TotalPriceOfMovie(IEnumerable<Movie> movies) { return movies.Where(m => m is Movie) .Sum(m => m.Price); } private static IEnumerable<Movie> GetMovies() { return new List<Movie>() { new Movie(), new MovieTransfer(), new Movie() }; } } public class Movie { public virtual int Price { get { return 2; } } } public class MovieTransfer : Movie { public override int Price { get { return 3; } } } pulbic static class LoopExtensions { public static void ForEach<T>(this IEnumerable<T> values, Action<T> action) { Contract.Requires(values != null); Contract.Requires(action != null); foreach (var v in values) action(v); } } .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } I think the new code is much cleaner than the first one, and I love the ForEach extension on the IEnumerable<T>, I can use it for different kind of things, for example: movies.Where(m => m is Movie) .ForEach(DoSomething); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } By using the Where and ForEach extension method, some if statements can be removed and will make the code much cleaner. But the beauty is in the eye of the beholder. What would you have done different, what do you think will make the first example in the blog post look much cleaner than my results, comments are welcome! If you want to know when I will publish a new blog post, you can follow me on twitter: http://www.twitter.com/fredrikn

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• Microsoft Introduces WebMatrix

  - by Rick Strahl

  originally published in CoDe Magazine Editorial Microsoft recently released the first CTP of a new development environment called WebMatrix, which along with some of its supporting technologies are squarely aimed at making the Microsoft Web Platform more approachable for first-time developers and hobbyists. But in the process, it also provides some updated technologies that can make life easier for existing .NET developers. Let’s face it: ASP.NET development isn’t exactly trivial unless you already have a fair bit of familiarity with sophisticated development practices. Stick a non-developer in front of Visual Studio .NET or even the Visual Web Developer Express edition and it’s not likely that the person in front of the screen will be very productive or feel inspired. Yet other technologies like PHP and even classic ASP did provide the ability for non-developers and hobbyists to become reasonably proficient in creating basic web content quickly and efficiently. WebMatrix appears to be Microsoft’s attempt to bring back some of that simplicity with a number of technologies and tools. The key is to provide a friendly and fully self-contained development environment that provides all the tools needed to build an application in one place, as well as tools that allow publishing of content and databases easily to the web server. WebMatrix is made up of several components and technologies: IIS Developer Express IIS Developer Express is a new, self-contained development web server that is fully compatible with IIS 7.5 and based on the same codebase that IIS 7.5 uses. This new development server replaces the much less compatible Cassini web server that’s been used in Visual Studio and the Express editions. IIS Express addresses a few shortcomings of the Cassini server such as the inability to serve custom ISAPI extensions (i.e., things like PHP or ASP classic for example), as well as not supporting advanced authentication. IIS Developer Express provides most of the IIS 7.5 feature set providing much better compatibility between development and live deployment scenarios. SQL Server Compact 4.0 Database access is a key component for most web-driven applications, but on the Microsoft stack this has mostly meant you have to use SQL Server or SQL Server Express. SQL Server Compact is not new-it’s been around for a few years, but it’s been severely hobbled in the past by terrible tool support and the inability to support more than a single connection in Microsoft’s attempt to avoid losing SQL Server licensing. The new release of SQL Server Compact 4.0 supports multiple connections and you can run it in ASP.NET web applications simply by installing an assembly into the bin folder of the web application. In effect, you don’t have to install a special system configuration to run SQL Compact as it is a drop-in database engine: Copy the small assembly into your BIN folder (or from the GAC if installed fully), create a connection string against a local file-based database file, and then start firing SQL requests. Additionally WebMatrix includes nice tools to edit the database tables and files, along with tools to easily upsize (and hopefully downsize in the future) to full SQL Server. This is a big win, pending compatibility and performance limits. In my simple testing the data engine performed well enough for small data sets. This is not only useful for web applications, but also for desktop applications for which a fully installed SQL engine like SQL Server would be overkill. Having a local data store in those applications that can potentially be accessed by multiple users is a welcome feature. ASP.NET Razor View Engine What? Yet another native ASP.NET view engine? We already have Web Forms and various different flavors of using that view engine with Web Forms and MVC. Do we really need another? Microsoft thinks so, and Razor is an implementation of a lightweight, script-only view engine. Unlike the Web Forms view engine, Razor works only with inline code, snippets, and markup; therefore, it is more in line with current thinking of what a view engine should represent. There’s no support for a “page model” or any of the other Web Forms features of the full-page framework, but just a lightweight scripting engine that works with plain markup plus embedded expressions and code. The markup syntax for Razor is geared for minimal typing, plus some progressive detection of where a script block/expression starts and ends. This results in a much leaner syntax than the typical ASP.NET Web Forms alligator (<% %>) tags. Razor uses the @ sign plus standard C# (or Visual Basic) block syntax to delineate code snippets and expressions. Here’s a very simple example of what Razor markup looks like along with some comment annotations: <!DOCTYPE html> <html>     <head>         <title></title>     </head>     <body>     <h1>Razor Test</h1>          <!-- simple expressions -->     @DateTime.Now     <hr />     <!-- method expressions -->     @DateTime.Now.ToString("T")          <!-- code blocks -->     @{         List<string> names = new List<string>();         names.Add("Rick");         names.Add("Markus");         names.Add("Claudio");         names.Add("Kevin");     }          <!-- structured block statements -->     <ul>     @foreach(string name in names){             <li>@name</li>     }     </ul>           <!-- Conditional code -->        @if(true) {                        <!-- Literal Text embedding in code -->        <text>         true        </text>;    }    else    {        <!-- Literal Text embedding in code -->       <text>       false       </text>;    }    </body> </html> Like the Web Forms view engine, Razor parses pages into code, and then executes that run-time compiled code. Effectively a “page” becomes a code file with markup becoming literal text written into the Response stream, code snippets becoming raw code, and expressions being written out with Response.Write(). The code generated from Razor doesn’t look much different from similar Web Forms code that only uses script tags; so although the syntax may look different, the operational model is fairly similar to the Web Forms engine minus the overhead of the large Page object model. However, there are differences: -Razor pages are based on a new base class, Microsoft.WebPages.WebPage, which is hosted in the Microsoft.WebPages assembly that houses all the Razor engine parsing and processing logic. Browsing through the assembly (in the generated ASP.NET Temporary Files folder or GAC) will give you a good idea of the functionality that Razor provides. If you look closely, a lot of the feature set matches ASP.NET MVC’s view implementation as well as many of the helper classes found in MVC. It’s not hard to guess the motivation for this sort of view engine: For beginning developers the simple markup syntax is easier to work with, although you obviously still need to have some understanding of the .NET Framework in order to create dynamic content. The syntax is easier to read and grok and much shorter to type than ASP.NET alligator tags (<% %>) and also easier to understand aesthetically what’s happening in the markup code. Razor also is a better fit for Microsoft’s vision of ASP.NET MVC: It’s a new view engine without the baggage of Web Forms attached to it. The engine is more lightweight since it doesn’t carry all the features and object model of Web Forms with it and it can be instantiated directly outside of the HTTP environment, which has been rather tricky to do for the Web Forms view engine. Having a standalone script parser is a huge win for other applications as well – it makes it much easier to create script or meta driven output generators for many types of applications from code/screen generators, to simple form letters to data merging applications with user customizability. For me personally this is very useful side effect and who knows maybe Microsoft will actually standardize they’re scripting engines (die T4 die!) on this engine. Razor also better fits the “view-based” approach where the view is supposed to be mostly a visual representation that doesn’t hold much, if any, code. While you can still use code, the code you do write has to be self-contained. Overall I wouldn’t be surprised if Razor will become the new standard view engine for MVC in the future – and in fact there have been announcements recently that Razor will become the default script engine in ASP.NET MVC 3.0. Razor can also be used in existing Web Forms and MVC applications, although that’s not working currently unless you manually configure the script mappings and add the appropriate assemblies. It’s possible to do it, but it’s probably better to wait until Microsoft releases official support for Razor scripts in Visual Studio. Once that happens, you can simply drop .cshtml and .vbhtml pages into an existing ASP.NET project and they will work side by side with classic ASP.NET pages. WebMatrix Development Environment To tie all of these three technologies together, Microsoft is shipping WebMatrix with an integrated development environment. An integrated gallery manager makes it easy to download and load existing projects, and then extend them with custom functionality. It seems to be a prominent goal to provide community-oriented content that can act as a starting point, be it via a custom templates or a complete standard application. The IDE includes a project manager that works with a single project and provides an integrated IDE/editor for editing the .cshtml and .vbhtml pages. A run button allows you to quickly run pages in the project manager in a variety of browsers. There’s no debugging support for code at this time. Note that Razor pages don’t require explicit compilation, so making a change, saving, and then refreshing your page in the browser is all that’s needed to see changes while testing an application locally. It’s essentially using the auto-compiling Web Project that was introduced with .NET 2.0. All code is compiled during run time into dynamically created assemblies in the ASP.NET temp folder. WebMatrix also has PHP Editing support with syntax highlighting. You can load various PHP-based applications from the WebMatrix Web Gallery directly into the IDE. Most of the Web Gallery applications are ready to install and run without further configuration, with Wizards taking you through installation of tools, dependencies, and configuration of the database as needed. WebMatrix leverages the Web Platform installer to pull the pieces down from websites in a tight integration of tools that worked nicely for the four or five applications I tried this out on. Click a couple of check boxes and fill in a few simple configuration options and you end up with a running application that’s ready to be customized. Nice! You can easily deploy completed applications via WebDeploy (to an IIS server) or FTP directly from within the development environment. The deploy tool also can handle automatically uploading and installing the database and all related assemblies required, making deployment a simple one-click install step. Simplified Database Access The IDE contains a database editor that can edit SQL Compact and SQL Server databases. There is also a Database helper class that facilitates database access by providing easy-to-use, high-level query execution and iteration methods: @{       var db = Database.OpenFile("FirstApp.sdf");     string sql = "select * from customers where Id > @0"; } <ul> @foreach(var row in db.Query(sql,1)){         <li>@row.FirstName @row.LastName</li> } </ul> The query function takes a SQL statement plus any number of positional (@0,@1 etc.) SQL parameters by simple values. The result is returned as a collection of rows which in turn have a row object with dynamic properties for each of the columns giving easy (though untyped) access to each of the fields. Likewise Execute and ExecuteNonQuery allow execution of more complex queries using similar parameter passing schemes. Note these queries use string-based queries rather than LINQ or Entity Framework’s strongly typed LINQ queries. While this may seem like a step back, it’s also in line with the expectations of non .NET script developers who are quite used to writing and using SQL strings in code rather than using OR/M frameworks. The only question is why was something not included from the beginning in .NET and Microsoft made developers build custom implementations of these basic building blocks. The implementation looks a lot like a DataTable-style data access mechanism, but to be fair, this is a common approach in scripting languages. This type of syntax that uses simple, static, data object methods to perform simple data tasks with one line of code are common in scripting languages and are a good match for folks working in PHP/Python, etc. Seems like Microsoft has taken great advantage of .NET 4.0’s dynamic typing to provide this sort of interface for row iteration where each row has properties for each field. FWIW, all the examples demonstrate using local SQL Compact files - I was unable to get a SQL Server connection string to work with the Database class (the connection string wasn’t accepted). However, since the code in the page is still plain old .NET, you can easily use standard ADO.NET code or even LINQ or Entity Framework models that are created outside of WebMatrix in separate assemblies as required. The good the bad the obnoxious - It’s still .NET The beauty (or curse depending on how you look at it :)) of Razor and the compilation model is that, behind it all, it’s still .NET. Although the syntax may look foreign, it’s still all .NET behind the scenes. You can easily access existing tools, helpers, and utilities simply by adding them to the project as references or to the bin folder. Razor automatically recognizes any assembly reference from assemblies in the bin folder. In the default configuration, Microsoft provides a host of helper functions in a Microsoft.WebPages assembly (check it out in the ASP.NET temp folder for your application), which includes a host of HTML Helpers. If you’ve used ASP.NET MVC before, a lot of the helpers should look familiar. Documentation at the moment is sketchy-there’s a very rough API reference you can check out here: http://www.asp.net/webmatrix/tutorials/asp-net-web-pages-api-reference Who needs WebMatrix? Uhm… good Question Clearly Microsoft is trying hard to create an environment with WebMatrix that is easy to use for newbie developers. The goal seems to be simplicity in providing a minimal development environment and an easy-to-use script engine/language that makes it easy to get started with. There’s also some focus on community features that can be used as starting points, such as Web Gallery applications and templates. The community features in particular are very nice and something that would be nice to eventually see in Visual Studio as well. The question is whether this is too little too late. Developers who have been clamoring for a simpler development environment on the .NET stack have mostly left for other simpler platforms like PHP or Python which are catering to the down and dirty developer. Microsoft will be hard pressed to win those folks-and other hardcore PHP developers-back. Regardless of how much you dress up a script engine fronted by the .NET Framework, it’s still the .NET Framework and all the complexity that drives it. While .NET is a fine solution in its breadth and features once you get a basic handle on the core features, the bar of entry to being productive with the .NET Framework is still pretty high. The MVC style helpers Microsoft provides are a good step in the right direction, but I suspect it’s not enough to shield new developers from having to delve much deeper into the Framework to get even basic applications built. Razor and its helpers is trying to make .NET more accessible but the reality is that in order to do useful stuff that goes beyond the handful of simple helpers you still are going to have to write some C# or VB or other .NET code. If the target is a hobby/amateur/non-programmer the learning curve isn’t made any easier by WebMatrix it’s just been shifted a tad bit further along in your development endeavor when you run out of canned components that are supplied either by Microsoft or the community. The database helpers are interesting and actually I’ve heard a lot of discussion from various developers who’ve been resisting .NET for a really long time perking up at the prospect of easier data access in .NET than the ridiculous amount of code it takes to do even simple data access with raw ADO.NET. It seems sad that such a simple concept and implementation should trigger this sort of response (especially since it’s practically trivial to create helpers like these or pick them up from countless libraries available), but there it is. It also shows that there are plenty of developers out there who are more interested in ‘getting stuff done’ easily than necessarily following the latest and greatest practices which are overkill for many development scenarios. Sometimes it seems that all of .NET is focused on the big life changing issues of development, rather than the bread and butter scenarios that many developers are interested in to get their work accomplished. And that in the end may be WebMatrix’s main raison d'être: To bring some focus back at Microsoft that simpler and more high level solutions are actually needed to appeal to the non-high end developers as well as providing the necessary tools for the high end developers who want to follow the latest and greatest trends. The current version of WebMatrix hits many sweet spots, but it also feels like it has a long way to go before it really can be a tool that a beginning developer or an accomplished developer can feel comfortable with. Although there are some really good ideas in the environment (like the gallery for downloading apps and components) which would be a great addition for Visual Studio as well, the rest of the development environment just feels like crippleware with required functionality missing especially debugging and Intellisense, but also general editor support. It’s not clear whether these are because the product is still in an early alpha release or whether it’s simply designed that way to be a really limited development environment. While simple can be good, nobody wants to feel left out when it comes to necessary tool support and WebMatrix just has that left out feeling to it. If anything WebMatrix’s technology pieces (which are really independent of the WebMatrix product) are what are interesting to developers in general. The compact IIS implementation is a nice improvement for development scenarios and SQL Compact 4.0 seems to address a lot of concerns that people have had and have complained about for some time with previous SQL Compact implementations. By far the most interesting and useful technology though seems to be the Razor view engine for its light weight implementation and it’s decoupling from the ASP.NET/HTTP pipeline to provide a standalone scripting/view engine that is pluggable. The first winner of this is going to be ASP.NET MVC which can now have a cleaner view model that isn’t inconsistent due to the baggage of non-implemented WebForms features that don’t work in MVC. But I expect that Razor will end up in many other applications as a scripting and code generation engine eventually. Visual Studio integration for Razor is currently missing, but is promised for a later release. The ASP.NET MVC team has already mentioned that Razor will eventually become the default MVC view engine, which will guarantee continued growth and development of this tool along those lines. And the Razor engine and support tools actually inherit many of the features that MVC pioneered, so there’s some synergy flowing both ways between Razor and MVC. As an existing ASP.NET developer who’s already familiar with Visual Studio and ASP.NET development, the WebMatrix IDE doesn’t give you anything that you want. The tools provided are minimal and provide nothing that you can’t get in Visual Studio today, except the minimal Razor syntax highlighting, so there’s little need to take a step back. With Visual Studio integration coming later there’s little reason to look at WebMatrix for tooling. It’s good to see that Microsoft is giving some thought about the ease of use of .NET as a platform For so many years, we’ve been piling on more and more new features without trying to take a step back and see how complicated the development/configuration/deployment process has become. Sometimes it’s good to take a step - or several steps - back and take another look and realize just how far we’ve come. WebMatrix is one of those reminders and one that likely will result in some positive changes on the platform as a whole. © Rick Strahl, West Wind Technologies, 2005-2010Posted in ASP.NET   IIS7  

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• Converting Lighttpd config to NginX with php-fpm

  - by Le Dude

  Having so much issue with NginX configuration since I'm new with NginX. Been using Lighttpd for quite sometime. Here are the base info. New Machine - CentOS 6.3 64 Bit - NginX 1.2.4-1.e16.ngx - Php-FPM 5.3.18-1.e16.remi Old Machine - CentOS 6.2 64Bit - Lighttpd 1.4.25-3.e16 Original Lighttpd config file: ####################################################################### ## ## /etc/lighttpd/lighttpd.conf ## ## check /etc/lighttpd/conf.d/*.conf for the configuration of modules. ## ####################################################################### ####################################################################### ## ## Some Variable definition which will make chrooting easier. ## ## if you add a variable here. Add the corresponding variable in the ## chroot example aswell. ## var.log_root = "/var/log/lighttpd" var.server_root = "/var/www" var.state_dir = "/var/run" var.home_dir = "/var/lib/lighttpd" var.conf_dir = "/etc/lighttpd" ## ## run the server chrooted. ## ## This requires root permissions during startup. ## ## If you run Chrooted set the the variables to directories relative to ## the chroot dir. ## ## example chroot configuration: ## #var.log_root = "/logs" #var.server_root = "/" #var.state_dir = "/run" #var.home_dir = "/lib/lighttpd" #var.vhosts_dir = "/vhosts" #var.conf_dir = "/etc" # #server.chroot = "/srv/www" ## ## Some additional variables to make the configuration easier ## ## ## Base directory for all virtual hosts ## ## used in: ## conf.d/evhost.conf ## conf.d/simple_vhost.conf ## vhosts.d/vhosts.template ## var.vhosts_dir = server_root + "/vhosts" ## ## Cache for mod_compress ## ## used in: ## conf.d/compress.conf ## var.cache_dir = "/var/cache/lighttpd" ## ## Base directory for sockets. ## ## used in: ## conf.d/fastcgi.conf ## conf.d/scgi.conf ## var.socket_dir = home_dir + "/sockets" ## ####################################################################### ####################################################################### ## ## Load the modules. include "modules.conf" ## ####################################################################### ####################################################################### ## ## Basic Configuration ## --------------------- ## server.port = 80 ## ## Use IPv6? ## #server.use-ipv6 = "enable" ## ## bind to a specific IP ## #server.bind = "localhost" ## ## Run as a different username/groupname. ## This requires root permissions during startup. ## server.username = "lighttpd" server.groupname = "lighttpd" ## ## enable core files. ## #server.core-files = "disable" ## ## Document root ## server.document-root = server_root + "/lighttpd" ## ## The value for the "Server:" response field. ## ## It would be nice to keep it at "lighttpd". ## #server.tag = "lighttpd" ## ## store a pid file ## server.pid-file = state_dir + "/lighttpd.pid" ## ####################################################################### ####################################################################### ## ## Logging Options ## ------------------ ## ## all logging options can be overwritten per vhost. ## ## Path to the error log file ## server.errorlog = log_root + "/error.log" ## ## If you want to log to syslog you have to unset the ## server.errorlog setting and uncomment the next line. ## #server.errorlog-use-syslog = "enable" ## ## Access log config ## include "conf.d/access_log.conf" ## ## The debug options are moved into their own file. ## see conf.d/debug.conf for various options for request debugging. ## include "conf.d/debug.conf" ## ####################################################################### ####################################################################### ## ## Tuning/Performance ## -------------------- ## ## corresponding documentation: ## http://www.lighttpd.net/documentation/performance.html ## ## set the event-handler (read the performance section in the manual) ## ## possible options on linux are: ## ## select ## poll ## linux-sysepoll ## ## linux-sysepoll is recommended on kernel 2.6. ## server.event-handler = "linux-sysepoll" ## ## The basic network interface for all platforms at the syscalls read() ## and write(). Every modern OS provides its own syscall to help network ## servers transfer files as fast as possible ## ## linux-sendfile - is recommended for small files. ## writev - is recommended for sending many large files ## server.network-backend = "linux-sendfile" ## ## As lighttpd is a single-threaded server, its main resource limit is ## the number of file descriptors, which is set to 1024 by default (on ## most systems). ## ## If you are running a high-traffic site you might want to increase this ## limit by setting server.max-fds. ## ## Changing this setting requires root permissions on startup. see ## server.username/server.groupname. ## ## By default lighttpd would not change the operation system default. ## But setting it to 2048 is a better default for busy servers. ## ## With SELinux enabled, this is denied by default and needs to be allowed ## by running the following once : setsebool -P httpd_setrlimit on server.max-fds = 2048 ## ## Stat() call caching. ## ## lighttpd can utilize FAM/Gamin to cache stat call. ## ## possible values are: ## disable, simple or fam. ## server.stat-cache-engine = "simple" ## ## Fine tuning for the request handling ## ## max-connections == max-fds/2 (maybe /3) ## means the other file handles are used for fastcgi/files ## server.max-connections = 1024 ## ## How many seconds to keep a keep-alive connection open, ## until we consider it idle. ## ## Default: 5 ## #server.max-keep-alive-idle = 5 ## ## How many keep-alive requests until closing the connection. ## ## Default: 16 ## #server.max-keep-alive-requests = 18 ## ## Maximum size of a request in kilobytes. ## By default it is unlimited (0). ## ## Uploads to your server cant be larger than this value. ## #server.max-request-size = 0 ## ## Time to read from a socket before we consider it idle. ## ## Default: 60 ## #server.max-read-idle = 60 ## ## Time to write to a socket before we consider it idle. ## ## Default: 360 ## #server.max-write-idle = 360 ## ## Traffic Shaping ## ----------------- ## ## see /usr/share/doc/lighttpd/traffic-shaping.txt ## ## Values are in kilobyte per second. ## ## Keep in mind that a limit below 32kB/s might actually limit the ## traffic to 32kB/s. This is caused by the size of the TCP send ## buffer. ## ## per server: ## #server.kbytes-per-second = 128 ## ## per connection: ## #connection.kbytes-per-second = 32 ## ####################################################################### ####################################################################### ## ## Filename/File handling ## ------------------------ ## ## files to check for if .../ is requested ## index-file.names = ( "index.php", "index.rb", "index.html", ## "index.htm", "default.htm" ) ## index-file.names += ( "index.xhtml", "index.html", "index.htm", "default.htm", "index.php" ) ## ## deny access the file-extensions ## ## ~ is for backupfiles from vi, emacs, joe, ... ## .inc is often used for code includes which should in general not be part ## of the document-root url.access-deny = ( "~", ".inc" ) ## ## disable range requests for pdf files ## workaround for a bug in the Acrobat Reader plugin. ## $HTTP["url"] =~ "\.pdf$" { server.range-requests = "disable" } ## ## url handling modules (rewrite, redirect) ## #url.rewrite = ( "^/$" => "/server-status" ) #url.redirect = ( "^/wishlist/(.+)" => "http://www.example.com/$1" ) ## ## both rewrite/redirect support back reference to regex conditional using %n ## #$HTTP["host"] =~ "^www\.(.*)" { # url.redirect = ( "^/(.*)" => "http://%1/$1" ) #} ## ## which extensions should not be handle via static-file transfer ## ## .php, .pl, .fcgi are most often handled by mod_fastcgi or mod_cgi ## static-file.exclude-extensions = ( ".php", ".pl", ".fcgi", ".scgi" ) ## ## error-handler for status 404 ## #server.error-handler-404 = "/error-handler.html" #server.error-handler-404 = "/error-handler.php" ## ## Format: <errorfile-prefix><status-code>.html ## -> ..../status-404.html for 'File not found' ## #server.errorfile-prefix = "/srv/www/htdocs/errors/status-" ## ## mimetype mapping ## include "conf.d/mime.conf" ## ## directory listing configuration ## include "conf.d/dirlisting.conf" ## ## Should lighttpd follow symlinks? ## server.follow-symlink = "enable" ## ## force all filenames to be lowercase? ## #server.force-lowercase-filenames = "disable" ## ## defaults to /var/tmp as we assume it is a local harddisk ## server.upload-dirs = ( "/var/tmp" ) ## ####################################################################### ####################################################################### ## ## SSL Support ## ------------- ## ## To enable SSL for the whole server you have to provide a valid ## certificate and have to enable the SSL engine.:: ## ## ssl.engine = "enable" ## ssl.pemfile = "/path/to/server.pem" ## ## The HTTPS protocol does not allow you to use name-based virtual ## hosting with SSL. If you want to run multiple SSL servers with ## one lighttpd instance you must use IP-based virtual hosting: :: ## ## $SERVER["socket"] == "10.0.0.1:443" { ## ssl.engine = "enable" ## ssl.pemfile = "/etc/ssl/private/www.example.com.pem" ## server.name = "www.example.com" ## ## server.document-root = "/srv/www/vhosts/example.com/www/" ## } ## ## If you have a .crt and a .key file, cat them together into a ## single PEM file: ## $ cat /etc/ssl/private/lighttpd.key /etc/ssl/certs/lighttpd.crt \ ## > /etc/ssl/private/lighttpd.pem ## #ssl.pemfile = "/etc/ssl/private/lighttpd.pem" ## ## optionally pass the CA certificate here. ## ## #ssl.ca-file = "" ## ####################################################################### ####################################################################### ## ## custom includes like vhosts. ## #include "conf.d/config.conf" #include_shell "cat /etc/lighttpd/vhosts.d/*.conf" ## ####################################################################### ####################################################################### ### Custom Added by me #url.rewrite-once = (".*\.(js|ico|gif|jpg|png|css|jar|class)$" => "$0", "" => "/index.php") url.rewrite-once = ( ".*\?(.*)$" => "/index.php?$1", "^/js/.*$" => "$0", "^.*\.(js|ico|gif|jpg|png|css|swf |jar|class)$" => "$0", "" => "/index.php" ) # expire.url = ( "" => "access 1 days" ) include "myvhost-vhosts.conf" ####################################################################### Here is my Vhost file for lighttpd $HTTP["host"] =~ "192.168.8.35$" { server.document-root = "/var/www/lighttpd/qc41022012/public" server.errorlog = "/var/log/lighttpd/error.log" accesslog.filename = "/var/log/lighttpd/access.log" server.error-handler-404 = "/e404.php" } and here is my nginx.conf file user nginx; worker_processes 5; error_log /var/log/nginx/error.log warn; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include /etc/nginx/mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log /var/log/nginx/testsite/logs/access.log main; sendfile on; #tcp_nopush on; keepalive_timeout 65; #gzip on; # include /etc/nginx/conf.d/*.conf; ## I added this ## include /etc/nginx/sites-available/*; } Here is my NginX Vhost file server { server_name 192.168.8.91; access_log /var/log/nginx/myapps/logs/access.log; error_log /var/log/nginx/myapps/logs/error.log; root /var/www/html/myapps/public; location / { index index.html index.htm index.php; } location = /favicon.ico { return 204; access_log off; log_not_found off; } # location ~ \.php$ { # try_files $uri /index.php; # include /etc/nginx/fastcgi_params; # fastcgi_pass 127.0.0.1:9000; # fastcgi_index index.php; # fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; # fastcgi_param SCRIPT_NAME $fastcgi_script_name; location ~ \.php.*$ { rewrite ^(.*.php)/ $1 last; fastcgi_pass 127.0.0.1:9000; fastcgi_index index.php; include fastcgi_params; fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name; # fastcgi_intercept_errors on; # fastcgi_param SCRIPT_FILENAME $document_root/index.php; # fastcgi_param PATH_INFO $uri; # fastcgi_pass 127.0.0.1:9000; # include fastcgi_params; } } We have a custom apps that we created that works great with lighttpd. I went through some headache also when we were trying to figure out how to make it work with lighttpd. this is the line that helps make it work in lighttpd. url.rewrite-once = ( ".*\?(.*)$" => "/index.php?$1", "^/js/.*$" => "$0", "^.*\.(js|ico|gif|jpg|png|css|swf |jar|class)$" => "$0", "" => "/index.php" ) but I couldn't figure out how to make it works in NginX. The webserver run just fine when we use the phpinfo.php test file. However as soon as I point it to my apps, nothing comes up. Check the error.log file and there's no error. Very mind boggling. I spent over 1 week trying to figure it out with no luck.. Please help?

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• Need help in setting lighttpd on Ubuntu 9.10

  - by hap497

  Hi, I am trying to run lighttpd on Ubuntu 9.10. I get the conf file from the doc directory of lighttpd source. $ sudo ./lighttpd -f lighttpd.conf $ ps -ef | grep lighttpd root 2094 1 0 19:40 ? 00:00:00 ./lighttpd -f lighttpd.conf This is my lighttpd.conf: $ more lighttpd.conf # lighttpd configuration file # # use it as a base for lighttpd 1.0.0 and above # # $Id: lighttpd.conf,v 1.7 2004/11/03 22:26:05 weigon Exp $ ############ Options you really have to take care of #################### ## modules to load # at least mod_access and mod_accesslog should be loaded # all other module should only be loaded if really neccesary # - saves some time # - saves memory server.modules = ( # "mod_rewrite", # "mod_redirect", # "mod_alias", "mod_access", # "mod_trigger_b4_dl", # "mod_auth", # "mod_status", # "mod_setenv", # "mod_fastcgi", # "mod_proxy", # "mod_simple_vhost", # "mod_evhost", # "mod_userdir", # "mod_cgi", # "mod_compress", # "mod_ssi", # "mod_usertrack", # "mod_expire", # "mod_secdownload", # "mod_rrdtool", "mod_accesslog" ) ## A static document-root. For virtual hosting take a look at the ## mod_simple_vhost module. server.document-root = "/srv/www/htdocs/" ## where to send error-messages to server.errorlog = "/var/log/lighttpd/error.log" # files to check for if .../ is requested index-file.names = ( "index.php", "index.html", "index.htm", "default.htm" ) ## set the event-handler (read the performance section in the manual) # server.event-handler = "freebsd-kqueue" # needed on OS X # mimetype mapping mimetype.assign = ( ".pdf" => "application/pdf", ".sig" => "application/pgp-signature", ".spl" => "application/futuresplash", ".class" => "application/octet-stream", ".ps" => "application/postscript", ".torrent" => "application/x-bittorrent", ".dvi" => "application/x-dvi", ".gz" => "application/x-gzip", ".pac" => "application/x-ns-proxy-autoconfig", ".swf" => "application/x-shockwave-flash", ".tar.gz" => "application/x-tgz", ".tgz" => "application/x-tgz", ".tar" => "application/x-tar", ".zip" => "application/zip", ".mp3" => "audio/mpeg", ".m3u" => "audio/x-mpegurl", ".wma" => "audio/x-ms-wma", ".wax" => "audio/x-ms-wax", ".ogg" => "application/ogg", ".wav" => "audio/x-wav", ".gif" => "image/gif", ".jar" => "application/x-java-archive", ".jpg" => "image/jpeg", ".jpeg" => "image/jpeg", ".png" => "image/png", ".xbm" => "image/x-xbitmap", ".xpm" => "image/x-xpixmap", ".xwd" => "image/x-xwindowdump", ".css" => "text/css", ".html" => "text/html", ".htm" => "text/html", ".js" => "text/javascript", ".asc" => "text/plain", ".c" => "text/plain", ".cpp" => "text/plain", ".log" => "text/plain", ".conf" => "text/plain", ".text" => "text/plain", ".txt" => "text/plain", ".dtd" => "text/xml", ".xml" => "text/xml", ".mpeg" => "video/mpeg", ".mpg" => "video/mpeg", ".mov" => "video/quicktime", ".qt" => "video/quicktime", ".avi" => "video/x-msvideo", ".asf" => "video/x-ms-asf", ".asx" => "video/x-ms-asf", ".wmv" => "video/x-ms-wmv", ".bz2" => "application/x-bzip", ".tbz" => "application/x-bzip-compressed-tar", ".tar.bz2" => "application/x-bzip-compressed-tar", # default mime type "" => "application/octet-stream", ) # Use the "Content-Type" extended attribute to obtain mime type if possible #mimetype.use-xattr = "enable" ## send a different Server: header ## be nice and keep it at lighttpd # server.tag = "lighttpd" #### accesslog module accesslog.filename = "/var/log/lighttpd/access.log" ## deny access the file-extensions # # ~ is for backupfiles from vi, emacs, joe, ... # .inc is often used for code includes which should in general not be part # of the document-root url.access-deny = ( "~", ".inc" ) $HTTP["url"] =~ "\.pdf$" { server.range-requests = "disable" } ## # which extensions should not be handle via static-file transfer # # .php, .pl, .fcgi are most often handled by mod_fastcgi or mod_cgi static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" ) ######### Options that are good to be but not neccesary to be changed ####### ## bind to port (default: 80) #server.port = 81 ## bind to localhost (default: all interfaces) #server.bind = "127.0.0.1" ## error-handler for status 404 #server.error-handler-404 = "/error-handler.html" #server.error-handler-404 = "/error-handler.php" ## to help the rc.scripts #server.pid-file = "/var/run/lighttpd.pid" ###### virtual hosts ## ## If you want name-based virtual hosting add the next three settings and load ## mod_simple_vhost ## ## document-root = ## virtual-server-root + virtual-server-default-host + virtual-server-docroot ## or ## virtual-server-root + http-host + virtual-server-docroot ## #simple-vhost.server-root = "/srv/www/vhosts/" #simple-vhost.default-host = "www.example.org" #simple-vhost.document-root = "/htdocs/" ## ## Format: <errorfile-prefix><status-code>.html ## -> ..../status-404.html for 'File not found' #server.errorfile-prefix = "/usr/share/lighttpd/errors/status-" #server.errorfile-prefix = "/srv/www/errors/status-" ## virtual directory listings #dir-listing.activate = "enable" ## select encoding for directory listings #dir-listing.encoding = "utf-8" ## enable debugging #debug.log-request-header = "enable" #debug.log-response-header = "enable" #debug.log-request-handling = "enable" #debug.log-file-not-found = "enable" ### only root can use these options # # chroot() to directory (default: no chroot() ) #server.chroot = "/" ## change uid to <uid> (default: don't care) #server.username = "wwwrun" ## change uid to <uid> (default: don't care) #server.groupname = "wwwrun" #### compress module #compress.cache-dir = "/var/cache/lighttpd/compress/" #compress.filetype = ("text/plain", "text/html") #### proxy module ## read proxy.txt for more info #proxy.server = ( ".php" => # ( "localhost" => # ( # "host" => "192.168.0.101", # "port" => 80 # ) # ) # ) #### fastcgi module ## read fastcgi.txt for more info ## for PHP don't forget to set cgi.fix_pathinfo = 1 in the php.ini #fastcgi.server = ( ".php" => # ( "localhost" => # ( # "socket" => "/var/run/lighttpd/php-fastcgi.s ocket", # "bin-path" => "/usr/local/bin/php-cgi" # ) # ) # ) #### CGI module #cgi.assign = ( ".pl" => "/usr/bin/perl", # ".cgi" => "/usr/bin/perl" ) # #### SSL engine #ssl.engine = "enable" #ssl.pemfile = "/etc/ssl/private/lighttpd.pem" #### status module #status.status-url = "/server-status" #status.config-url = "/server-config" #### auth module ## read authentication.txt for more info #auth.backend = "plain" #auth.backend.plain.userfile = "lighttpd.user" #auth.backend.plain.groupfile = "lighttpd.group" #auth.backend.ldap.hostname = "localhost" #auth.backend.ldap.base-dn = "dc=my-domain,dc=com" #auth.backend.ldap.filter = "(uid=$)" #auth.require = ( "/server-status" => # ( # "method" => "digest", # "realm" => "download archiv", # "require" => "user=jan" # ), # "/server-config" => # ( # "method" => "digest", # "realm" => "download archiv", # "require" => "valid-user" # ) # ) #### url handling modules (rewrite, redirect, access) #url.rewrite = ( "^/$" => "/server-status" ) #url.redirect = ( "^/wishlist/(.+)" => "http://www.123.org/$1" ) #### both rewrite/redirect support back reference to regex conditional using %n #$HTTP["host"] =~ "^www\.(.*)" { # url.redirect = ( "^/(.*)" => "http://%1/$1" ) #} # # define a pattern for the host url finding # %% => % sign # %0 => domain name + tld # %1 => tld # %2 => domain name without tld # %3 => subdomain 1 name # %4 => subdomain 2 name # #evhost.path-pattern = "/srv/www/vhosts/%3/htdocs/" #### expire module #expire.url = ( "/buggy/" => "access 2 hours", "/asdhas/" => "ac cess plus 1 seconds 2 minutes") #### ssi #ssi.extension = ( ".shtml" ) #### rrdtool #rrdtool.binary = "/usr/bin/rrdtool" #rrdtool.db-name = "/var/lib/lighttpd/lighttpd.rrd" #### setenv #setenv.add-request-header = ( "TRAV_ENV" => "mysql://user@host/db" ) #setenv.add-response-header = ( "X-Secret-Message" => "42" ) ## for mod_trigger_b4_dl # trigger-before-download.gdbm-filename = "/var/lib/lighttpd/trigger.db" # trigger-before-download.memcache-hosts = ( "127.0.0.1:11211" ) # trigger-before-download.trigger-url = "^/trigger/" # trigger-before-download.download-url = "^/download/" # trigger-before-download.deny-url = "http://127.0.0.1/index.html" # trigger-before-download.trigger-timeout = 10 #### variable usage: ## variable name without "." is auto prefixed by "var." and becomes "var.bar" #bar = 1 #var.mystring = "foo" ## integer add #bar += 1 ## string concat, with integer cast as string, result: "www.foo1.com" #server.name = "www." + mystring + var.bar + ".com" ## array merge #index-file.names = (foo + ".php") + index-file.names #index-file.names += (foo + ".php") #### include #include /etc/lighttpd/lighttpd-inc.conf ## same as above if you run: "lighttpd -f /etc/lighttpd/lighttpd.conf" #include "lighttpd-inc.conf" #### include_shell #include_shell "echo var.a=1" ## the above is same as: #var.a=1 When I go to browser and hit 'http://127.0.0.1', I get link not found. Any idea?

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• How to configure fastcgi to work with ligttpd in ubuntu

  - by michael

  I am able to run lighttpd on ubuntu 9.10. But when i tried to setup fastcgi with lighttpd by putting this in the ligttpd.conf file: #### fastcgi module fastcgi.server = ( "/fastcgi_scripts/" => (( "host" => "127.0.0.1", "port" => "9098", "check-local" => "disable", "bin-path" => "/usr/local/bin/cgi-fcgi", "docroot" => "/" # remote server may use # it's own docroot )) ) This is what I get in the error.log in ligttpd: 2010-03-07 21:00:11: (log.c.166) server started 2010-03-07 21:00:11: (mod_fastcgi.c.1104) the fastcgi-backend /usr/local/bin/cgi-fcgi failed to start: 2010-03-07 21:00:11: (mod_fastcgi.c.1108) child exited with status 1 /usr/local/bin/cgi-fcgi 2010-03-07 21:00:11: (mod_fastcgi.c.1111) If you're trying to run your app as a FastCGI backend, make sure you're using the FastCGI-enabled version. If this is PHP on Gentoo, add 'fastcgi' to the USE flags. 2010-03-07 21:00:11: (mod_fastcgi.c.1399) [ERROR]: spawning fcgi failed. 2010-03-07 21:00:11: (server.c.931) Configuration of plugins failed. Going down. I do have cgi-fcgi in /usr/local/bin: $ which cgi-fcgi /usr/local/bin/cgi-fcgi '/usr/local/bin/cgi-fcgi' is the executable after I download and compile fast-cgi. Here is my lighttpd conf file: $ more lighttpd.conf # lighttpd configuration file # # use it as a base for lighttpd 1.0.0 and above # # $Id: lighttpd.conf,v 1.7 2004/11/03 22:26:05 weigon Exp $ ############ Options you really have to take care of #################### ## modules to load # at least mod_access and mod_accesslog should be loaded # all other module should only be loaded if really neccesary # - saves some time # - saves memory server.modules = ( # "mod_rewrite", # "mod_redirect", # "mod_alias", "mod_access", # "mod_trigger_b4_dl", # "mod_auth", # "mod_status", # "mod_setenv", "mod_fastcgi", # "mod_proxy", # "mod_simple_vhost", # "mod_evhost", # "mod_userdir", # "mod_cgi", # "mod_compress", # "mod_ssi", # "mod_usertrack", # "mod_expire", # "mod_secdownload", # "mod_rrdtool", "mod_accesslog" ) ## A static document-root. For virtual hosting take a look at the ## mod_simple_vhost module. server.document-root = "/srv/www/htdocs/" ## where to send error-messages to server.errorlog = "/var/log/lighttpd/error.log" # files to check for if .../ is requested index-file.names = ( "index.php", "index.html", "index.htm", "default.htm" ) ## set the event-handler (read the performance section in the manual) # server.event-handler = "freebsd-kqueue" # needed on OS X # mimetype mapping mimetype.assign = ( ".pdf" => "application/pdf", ".sig" => "application/pgp-signature", ".spl" => "application/futuresplash", ".class" => "application/octet-stream", ".ps" => "application/postscript", ".torrent" => "application/x-bittorrent", ".dvi" => "application/x-dvi", ".gz" => "application/x-gzip", ".pac" => "application/x-ns-proxy-autoconfig", ".swf" => "application/x-shockwave-flash", ".tar.gz" => "application/x-tgz", ".tgz" => "application/x-tgz", ".tar" => "application/x-tar", ".zip" => "application/zip", ".mp3" => "audio/mpeg", ".m3u" => "audio/x-mpegurl", ".wma" => "audio/x-ms-wma", ".wax" => "audio/x-ms-wax", ".ogg" => "application/ogg", ".wav" => "audio/x-wav", ".gif" => "image/gif", ".jar" => "application/x-java-archive", ".jpg" => "image/jpeg", ".jpeg" => "image/jpeg", ".png" => "image/png", ".xbm" => "image/x-xbitmap", ".xpm" => "image/x-xpixmap", ".xwd" => "image/x-xwindowdump", ".css" => "text/css", ".html" => "text/html", ".htm" => "text/html", ".js" => "text/javascript", ".asc" => "text/plain", ".c" => "text/plain", ".cpp" => "text/plain", ".log" => "text/plain", ".conf" => "text/plain", ".text" => "text/plain", ".txt" => "text/plain", ".dtd" => "text/xml", ".xml" => "text/xml", ".mpeg" => "video/mpeg", ".mpg" => "video/mpeg", ".mov" => "video/quicktime", ".qt" => "video/quicktime", ".avi" => "video/x-msvideo", ".asf" => "video/x-ms-asf", ".asx" => "video/x-ms-asf", ".wmv" => "video/x-ms-wmv", ".bz2" => "application/x-bzip", ".tbz" => "application/x-bzip-compressed-tar", ".tar.bz2" => "application/x-bzip-compressed-tar", # default mime type "" => "application/octet-stream", ) # Use the "Content-Type" extended attribute to obtain mime type if possible #mimetype.use-xattr = "enable" ## send a different Server: header ## be nice and keep it at lighttpd # server.tag = "lighttpd" #### accesslog module accesslog.filename = "/var/log/lighttpd/access.log" ## deny access the file-extensions # # ~ is for backupfiles from vi, emacs, joe, ... # .inc is often used for code includes which should in general not be part # of the document-root url.access-deny = ( "~", ".inc" ) $HTTP["url"] =~ "\.pdf$" { server.range-requests = "disable" } ## # which extensions should not be handle via static-file transfer # # .php, .pl, .fcgi are most often handled by mod_fastcgi or mod_cgi static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" ) ######### Options that are good to be but not neccesary to be changed ####### ## bind to port (default: 80) server.port = 9090 ## bind to localhost (default: all interfaces) server.bind = "127.0.0.1" ## error-handler for status 404 #server.error-handler-404 = "/error-handler.html" #server.error-handler-404 = "/error-handler.php" ## to help the rc.scripts #server.pid-file = "/var/run/lighttpd.pid" ###### virtual hosts ## ## If you want name-based virtual hosting add the next three settings and load ## mod_simple_vhost ## ## document-root = ## virtual-server-root + virtual-server-default-host + virtual-server-docroot ## or ## virtual-server-root + http-host + virtual-server-docroot ## #simple-vhost.server-root = "/srv/www/vhosts/" #simple-vhost.default-host = "www.example.org" #simple-vhost.document-root = "/htdocs/" ## ## Format: <errorfile-prefix><status-code>.html ## -> ..../status-404.html for 'File not found' #server.errorfile-prefix = "/usr/share/lighttpd/errors/status-" #server.errorfile-prefix = "/srv/www/errors/status-" ## virtual directory listings #dir-listing.activate = "enable" ## select encoding for directory listings #dir-listing.encoding = "utf-8" ## enable debugging #debug.log-request-header = "enable" #debug.log-response-header = "enable" #debug.log-request-handling = "enable" #debug.log-file-not-found = "enable" ### only root can use these options # # chroot() to directory (default: no chroot() ) #server.chroot = "/" ## change uid to <uid> (default: don't care) #server.username = "wwwrun" ## change uid to <uid> (default: don't care) #server.groupname = "wwwrun" #### compress module #compress.cache-dir = "/var/cache/lighttpd/compress/" #compress.filetype = ("text/plain", "text/html") #### proxy module ## read proxy.txt for more info #proxy.server = ( ".php" => # ( "localhost" => # ( # "host" => "192.168.0.101", # "port" => 80 # ) # ) # ) #### fastcgi module fastcgi.server = ( "/fastcgi_scripts/" => (( "host" => "127.0.0.1", "port" => 1026, "check-local" => "disable", "bin-path" => "/usr/local/bin/cgi-fcgi", #"docroot" => "/" # remote server may use # it's own docroot )) ) ## read fastcgi.txt for more info ## for PHP don't forget to set cgi.fix_pathinfo = 1 in the php.ini #fastcgi.server = ( ".php" => # ( "localhost" => # ( # "socket" => "/var/run/lighttpd/php-fastcgi.s ocket", # "bin-path" => "/usr/local/bin/php-cgi" # ) # ) # ) #### CGI module #cgi.assign = ( ".pl" => "/usr/bin/perl", # ".cgi" => "/usr/bin/perl" ) # #### SSL engine #ssl.engine = "enable" #ssl.pemfile = "/etc/ssl/private/lighttpd.pem" #### status module #status.status-url = "/server-status" #status.config-url = "/server-config" #### auth module ## read authentication.txt for more info #auth.backend = "plain" #auth.backend.plain.userfile = "lighttpd.user" #auth.backend.plain.groupfile = "lighttpd.group" #auth.backend.ldap.hostname = "localhost" #auth.backend.ldap.base-dn = "dc=my-domain,dc=com" #auth.backend.ldap.filter = "(uid=$)" #auth.require = ( "/server-status" => # ( # "method" => "digest", # "realm" => "download archiv", # "require" => "user=jan" # ), # "/server-config" => # ( # "method" => "digest", # "realm" => "download archiv", # "require" => "valid-user" # ) # ) #### url handling modules (rewrite, redirect, access) #url.rewrite = ( "^/$" => "/server-status" ) #url.redirect = ( "^/wishlist/(.+)" => "http://www.123.org/$1" ) #### both rewrite/redirect support back reference to regex conditional using %n #$HTTP["host"] =~ "^www\.(.*)" { # url.redirect = ( "^/(.*)" => "http://%1/$1" ) #} # # define a pattern for the host url finding # %% => % sign # %0 => domain name + tld # %1 => tld # %2 => domain name without tld # %3 => subdomain 1 name # %4 => subdomain 2 name # #evhost.path-pattern = "/srv/www/vhosts/%3/htdocs/" #### expire module #expire.url = ( "/buggy/" => "access 2 hours", "/asdhas/" => "ac cess plus 1 seconds 2 minutes") #### ssi #ssi.extension = ( ".shtml" ) #### rrdtool #rrdtool.binary = "/usr/bin/rrdtool" #rrdtool.db-name = "/var/lib/lighttpd/lighttpd.rrd" #### setenv #setenv.add-request-header = ( "TRAV_ENV" => "mysql://user@host/db" ) #setenv.add-response-header = ( "X-Secret-Message" => "42" ) ## for mod_trigger_b4_dl # trigger-before-download.gdbm-filename = "/var/lib/lighttpd/trigger.db" # trigger-before-download.memcache-hosts = ( "127.0.0.1:11211" ) # trigger-before-download.trigger-url = "^/trigger/" # trigger-before-download.download-url = "^/download/" # trigger-before-download.deny-url = "http://127.0.0.1/index.html" # trigger-before-download.trigger-timeout = 10 #### variable usage: ## variable name without "." is auto prefixed by "var." and becomes "var.bar" #bar = 1 #var.mystring = "foo" ## integer add #bar += 1 ## string concat, with integer cast as string, result: "www.foo1.com" #server.name = "www." + mystring + var.bar + ".com" ## array merge #index-file.names = (foo + ".php") + index-file.names #index-file.names += (foo + ".php") #### include #include /etc/lighttpd/lighttpd-inc.conf ## same as above if you run: "lighttpd -f /etc/lighttpd/lighttpd.conf" #include "lighttpd-inc.conf" #### include_shell #include_shell "echo var.a=1" ## the above is same as: #var.a=1 Thank you for your help.

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• ServerRoot in my lighttpd.conf

  - by michael

  Hi, I have use the following example lighttpd.conf to launch my lighttpd. Can you please tell me where is my 'ServerRoot'? # lighttpd configuration file # # use it as a base for lighttpd 1.0.0 and above # # $Id: lighttpd.conf,v 1.7 2004/11/03 22:26:05 weigon Exp $ ############ Options you really have to take care of #################### ## modules to load # at least mod_access and mod_accesslog should be loaded # all other module should only be loaded if really neccesary # - saves some time # - saves memory server.modules = ( # "mod_rewrite", # "mod_redirect", # "mod_alias", "mod_access", # "mod_trigger_b4_dl", # "mod_auth", # "mod_status", # "mod_setenv", "mod_fastcgi", # "mod_proxy", # "mod_simple_vhost", # "mod_evhost", # "mod_userdir", # "mod_cgi", # "mod_compress", # "mod_ssi", # "mod_usertrack", # "mod_expire", # "mod_secdownload", # "mod_rrdtool", "mod_accesslog" ) ## A static document-root. For virtual hosting take a look at the ## mod_simple_vhost module. server.document-root = "/srv/www/htdocs/" ## where to send error-messages to server.errorlog = "/var/log/lighttpd/error.log" # files to check for if .../ is requested index-file.names = ( "index.php", "index.html", "index.htm", "default.htm" ) ## set the event-handler (read the performance section in the manual) # server.event-handler = "freebsd-kqueue" # needed on OS X # mimetype mapping mimetype.assign = ( ".pdf" => "application/pdf", ".sig" => "application/pgp-signature", ".spl" => "application/futuresplash", ".class" => "application/octet-stream", ".ps" => "application/postscript", ".torrent" => "application/x-bittorrent", ".dvi" => "application/x-dvi", ".gz" => "application/x-gzip", ".pac" => "application/x-ns-proxy-autoconfig", ".swf" => "application/x-shockwave-flash", ".tar.gz" => "application/x-tgz", ".tgz" => "application/x-tgz", ".tar" => "application/x-tar", ".zip" => "application/zip", ".mp3" => "audio/mpeg", ".m3u" => "audio/x-mpegurl", ".wma" => "audio/x-ms-wma", ".wax" => "audio/x-ms-wax", ".ogg" => "application/ogg", ".wav" => "audio/x-wav", ".gif" => "image/gif", ".jar" => "application/x-java-archive", ".jpg" => "image/jpeg", ".jpeg" => "image/jpeg", ".png" => "image/png", ".xbm" => "image/x-xbitmap", ".xpm" => "image/x-xpixmap", ".xwd" => "image/x-xwindowdump", ".css" => "text/css", ".html" => "text/html", ".htm" => "text/html", ".js" => "text/javascript", ".asc" => "text/plain", ".c" => "text/plain", ".cpp" => "text/plain", ".log" => "text/plain", ".conf" => "text/plain", ".text" => "text/plain", ".txt" => "text/plain", ".dtd" => "text/xml", ".xml" => "text/xml", ".mpeg" => "video/mpeg", ".mpg" => "video/mpeg", ".mov" => "video/quicktime", ".qt" => "video/quicktime", ".avi" => "video/x-msvideo", ".asf" => "video/x-ms-asf", ".asx" => "video/x-ms-asf", ".wmv" => "video/x-ms-wmv", ".bz2" => "application/x-bzip", ".tbz" => "application/x-bzip-compressed-tar", ".tar.bz2" => "application/x-bzip-compressed-tar", # default mime type "" => "application/octet-stream", ) # Use the "Content-Type" extended attribute to obtain mime type if possible #mimetype.use-xattr = "enable" ## send a different Server: header ## be nice and keep it at lighttpd # server.tag = "lighttpd" #### accesslog module accesslog.filename = "/var/log/lighttpd/access.log" ## deny access the file-extensions # # ~ is for backupfiles from vi, emacs, joe, ... # .inc is often used for code includes which should in general not be part # of the document-root url.access-deny = ( "~", ".inc" ) $HTTP["url"] =~ "\.pdf$" { server.range-requests = "disable" } ## # which extensions should not be handle via static-file transfer # # .php, .pl, .fcgi are most often handled by mod_fastcgi or mod_cgi static-file.exclude-extensions = ( ".php", ".pl", ".fcgi" ) ######### Options that are good to be but not neccesary to be changed ####### ## bind to port (default: 80) server.port = 9090 ## bind to localhost (default: all interfaces) server.bind = "127.0.0.1" ## error-handler for status 404 #server.error-handler-404 = "/error-handler.html" #server.error-handler-404 = "/error-handler.php" ## to help the rc.scripts #server.pid-file = "/var/run/lighttpd.pid" ###### virtual hosts ## ## If you want name-based virtual hosting add the next three settings and load ## mod_simple_vhost ## ## document-root = ## virtual-server-root + virtual-server-default-host + virtual-server-docroot ## or ## virtual-server-root + http-host + virtual-server-docroot ## #simple-vhost.server-root = "/srv/www/vhosts/" #simple-vhost.default-host = "www.example.org" #simple-vhost.document-root = "/htdocs/" ## ## Format: <errorfile-prefix><status-code>.html ## -> ..../status-404.html for 'File not found' #server.errorfile-prefix = "/usr/share/lighttpd/errors/status-" #server.errorfile-prefix = "/srv/www/errors/status-" ## virtual directory listings #dir-listing.activate = "enable" ## select encoding for directory listings #dir-listing.encoding = "utf-8" ## enable debugging #debug.log-request-header = "enable" #debug.log-response-header = "enable" #debug.log-request-handling = "enable" #debug.log-file-not-found = "enable" ### only root can use these options # # chroot() to directory (default: no chroot() ) #server.chroot = "/" ## change uid to <uid> (default: don't care) #server.username = "wwwrun" ## change uid to <uid> (default: don't care) #server.groupname = "wwwrun" #### compress module #compress.cache-dir = "/var/cache/lighttpd/compress/" #compress.filetype = ("text/plain", "text/html") #### proxy module ## read proxy.txt for more info #proxy.server = ( ".php" => # ( "localhost" => # ( # "host" => "192.168.0.101", # "port" => 80 # ) # ) # ) #### fastcgi module fastcgi.server = ( "/fastcgi_scripts/" => (( "host" => "127.0.0.1", "port" => 1026, "check-local" => "disable", "bin-path" => "/usr/local/bin/cgi-fcgi", #"docroot" => "/" # remote server may use # it's own docroot )) ) ## read fastcgi.txt for more info ## for PHP don't forget to set cgi.fix_pathinfo = 1 in the php.ini #fastcgi.server = ( ".php" => # ( "localhost" => # ( # "socket" => "/var/run/lighttpd/php-fastcgi.socket", # "bin-path" => "/usr/local/bin/php-cgi" # ) # ) # ) #### CGI module #cgi.assign = ( ".pl" => "/usr/bin/perl", # ".cgi" => "/usr/bin/perl" ) # #### SSL engine #ssl.engine = "enable" #ssl.pemfile = "/etc/ssl/private/lighttpd.pem" #### status module #status.status-url = "/server-status" #status.config-url = "/server-config" #### auth module ## read authentication.txt for more info #auth.backend = "plain" #auth.backend.plain.userfile = "lighttpd.user" #auth.backend.plain.groupfile = "lighttpd.group" #auth.backend.ldap.hostname = "localhost" #auth.backend.ldap.base-dn = "dc=my-domain,dc=com" #auth.backend.ldap.filter = "(uid=$)" #auth.require = ( "/server-status" => # ( # "method" => "digest", # "realm" => "download archiv", # "require" => "user=jan" # ), # "/server-config" => # ( # "method" => "digest", # "realm" => "download archiv", # "require" => "valid-user" # ) # ) #### url handling modules (rewrite, redirect, access) #url.rewrite = ( "^/$" => "/server-status" ) #url.redirect = ( "^/wishlist/(.+)" => "http://www.123.org/$1" ) #### both rewrite/redirect support back reference to regex conditional using %n #$HTTP["host"] =~ "^www\.(.*)" { # url.redirect = ( "^/(.*)" => "http://%1/$1" ) #} # # define a pattern for the host url finding # %% => % sign # %0 => domain name + tld # %1 => tld # %2 => domain name without tld # %3 => subdomain 1 name # %4 => subdomain 2 name # #evhost.path-pattern = "/srv/www/vhosts/%3/htdocs/" #### expire module #expire.url = ( "/buggy/" => "access 2 hours", "/asdhas/" => "access plus 1 seconds 2 minutes") #### ssi #ssi.extension = ( ".shtml" ) #### rrdtool #rrdtool.binary = "/usr/bin/rrdtool" #rrdtool.db-name = "/var/lib/lighttpd/lighttpd.rrd" #### setenv #setenv.add-request-header = ( "TRAV_ENV" => "mysql://user@host/db" ) #setenv.add-response-header = ( "X-Secret-Message" => "42" ) ## for mod_trigger_b4_dl # trigger-before-download.gdbm-filename = "/var/lib/lighttpd/trigger.db" # trigger-before-download.memcache-hosts = ( "127.0.0.1:11211" ) # trigger-before-download.trigger-url = "^/trigger/" # trigger-before-download.download-url = "^/download/" # trigger-before-download.deny-url = "http://127.0.0.1/index.html" # trigger-before-download.trigger-timeout = 10 #### variable usage: ## variable name without "." is auto prefixed by "var." and becomes "var.bar" #bar = 1 #var.mystring = "foo" ## integer add #bar += 1 ## string concat, with integer cast as string, result: "www.foo1.com" #server.name = "www." + mystring + var.bar + ".com" ## array merge #index-file.names = (foo + ".php") + index-file.names #index-file.names += (foo + ".php") #### include #include /etc/lighttpd/lighttpd-inc.conf ## same as above if you run: "lighttpd -f /etc/lighttpd/lighttpd.conf" #include "lighttpd-inc.conf" #### include_shell #include_shell "echo var.a=1" ## the above is same as: #var.a=1 Thank you.

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• Mysql - help me optimize this query

  - by sandeepan-nath

  About the system: -The system has a total of 8 tables - Users - Tutor_Details (Tutors are a type of User,Tutor_Details table is linked to Users) - learning_packs, (stores packs created by tutors) - learning_packs_tag_relations, (holds tag relations meant for search) - tutors_tag_relations and tags and orders (containing purchase details of tutor's packs), order_details linked to orders and tutor_details. For a more clear idea about the tables involved please check the The tables section in the end. -A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below. Following is a simpler representation (not the actual) of the more complex query which I am trying to optimize:- I have used statements like explanation of parts in the query select SUM(DISTINCT( t.tag LIKE "%Dictatorship%" )) as key_1_total_matches, SUM(DISTINCT( t.tag LIKE "%democracy%" )) as key_2_total_matches, td., u., count(distinct(od.id_od)), if (lp.id_lp > 0) then some conditional logic on lp fields else 0 as tutor_popularity from Tutor_Details AS td JOIN Users as u on u.id_user = td.id_user LEFT JOIN Learning_Packs_Tag_Relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN Learning_Packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN `some other tables on lp.id_lp - let's call learning pack tables set (including Learning_Packs table)` LEFT JOIN Order_Details as od on td.id_tutor = od.id_author LEFT JOIN Orders as o on od.id_order = o.id_order LEFT JOIN Tutors_Tag_Relations as ttagrels ON td.id_tutor = ttagrels.id_tutor JOIN Tags as t on (t.id_tag = ttagrels.id_tag) OR (t.id_tag = lptagrels.id_tag) where some condition on Users table's fields AND CASE WHEN ((t.id_tag = lptagrels.id_tag) AND (lp.id_lp 0)) THEN `some conditions on learning pack tables set` ELSE 1 END AND CASE WHEN ((t.id_tag = wtagrels.id_tag) AND (wc.id_wc 0)) THEN `some conditions on webclasses tables set` ELSE 1 END AND CASE WHEN (od.id_od0) THEN od.id_author = td.id_tutor and some conditions on Orders table's fields ELSE 1 END AND ( t.tag LIKE "%Dictatorship%" OR t.tag LIKE "%democracy%") group by td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 order by tutor_popularity desc, u.surname asc, u.name asc limit 0,20 ===================================================================== What does the above query do? Does AND logic search on the search keywords (2 in this example - "Democracy" and "Dictatorship"). Returns only those tutors for which both the keywords are present in the union of the two sets - tutors details and details of all the packs created by a tutor. To make things clear - Suppose a Tutor name "Sandeepan Nath" has created a pack "My first pack", then:- Searching "Sandeepan Nath" returns Sandeepan Nath. Searching "Sandeepan first" returns Sandeepan Nath. Searching "Sandeepan second" does not return Sandeepan Nath. ====================================================================================== The problem The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query on heavily loaded databases is like 25 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable. It is possible that some of the delay is being caused because all the possible fields have not yet been indexed, but I would appreciate a better query as a solution, optimized as much as possible, displaying the same results ========================================================================================== How tags work in this system? When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc. When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc. tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table. ==================================================================== The tables Most of the following tables contain many other fields which I have omitted here. CREATE TABLE IF NOT EXISTS users ( id_user int(10) unsigned NOT NULL AUTO_INCREMENT, name varchar(100) NOT NULL DEFAULT '', surname varchar(155) NOT NULL DEFAULT '', PRIMARY KEY (id_user) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=636 ; CREATE TABLE IF NOT EXISTS tutor_details ( id_tutor int(10) NOT NULL AUTO_INCREMENT, id_user int(10) NOT NULL DEFAULT '0', PRIMARY KEY (id_tutor), KEY Users_FKIndex1 (id_user) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=51 ; CREATE TABLE IF NOT EXISTS orders ( id_order int(10) unsigned NOT NULL AUTO_INCREMENT, PRIMARY KEY (id_order), KEY Orders_FKIndex1 (id_user), ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=275 ; ALTER TABLE orders ADD CONSTRAINT Orders_ibfk_1 FOREIGN KEY (id_user) REFERENCES users (id_user) ON DELETE NO ACTION ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS order_details ( id_od int(10) unsigned NOT NULL AUTO_INCREMENT, id_order int(10) unsigned NOT NULL DEFAULT '0', id_author int(10) NOT NULL DEFAULT '0', PRIMARY KEY (id_od), KEY Order_Details_FKIndex1 (id_order) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=284 ; ALTER TABLE order_details ADD CONSTRAINT Order_Details_ibfk_1 FOREIGN KEY (id_order) REFERENCES orders (id_order) ON DELETE NO ACTION ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS learning_packs ( id_lp int(10) unsigned NOT NULL AUTO_INCREMENT, id_author int(10) unsigned NOT NULL DEFAULT '0', PRIMARY KEY (id_lp), KEY Learning_Packs_FKIndex2 (id_author), KEY id_lp (id_lp) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=23 ; CREATE TABLE IF NOT EXISTS tags ( id_tag int(10) unsigned NOT NULL AUTO_INCREMENT, tag varchar(255) DEFAULT NULL, PRIMARY KEY (id_tag), UNIQUE KEY tag (tag), KEY id_tag (id_tag), KEY tag_2 (tag), KEY tag_3 (tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=3419 ; CREATE TABLE IF NOT EXISTS tutors_tag_relations ( id_tag int(10) unsigned NOT NULL DEFAULT '0', id_tutor int(10) DEFAULT NULL, KEY Tutors_Tag_Relations (id_tag), KEY id_tutor (id_tutor), KEY id_tag (id_tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; ALTER TABLE tutors_tag_relations ADD CONSTRAINT Tutors_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS learning_packs_tag_relations ( id_tag int(10) unsigned NOT NULL DEFAULT '0', id_tutor int(10) DEFAULT NULL, id_lp int(10) unsigned DEFAULT NULL, KEY Learning_Packs_Tag_Relations_FKIndex1 (id_tag), KEY id_lp (id_lp), KEY id_tag (id_tag) ) ENGINE=InnoDB DEFAULT CHARSET=latin1; ALTER TABLE learning_packs_tag_relations ADD CONSTRAINT Learning_Packs_Tag_Relations_ibfk_1 FOREIGN KEY (id_tag) REFERENCES tags (id_tag) ON DELETE NO ACTION ON UPDATE NO ACTION; =================================================================================== Following is the exact query (this includes classes also - tutors can create classes and search terms are matched with classes created by tutors):- select count(distinct(od.id_od)) as tutor_popularity, CASE WHEN (IF((wc.id_wc 0), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND (wccp.country_code='IE' or wccp.country_code IN ('INT'))), 0)) THEN 1 ELSE 0 END as 'classes_published', CASE WHEN (IF((lp.id_lp 0), (lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND (lpcp.country_code='IE' or lpcp.country_code IN ('INT'))),0)) THEN 1 ELSE 0 END as 'packs_published', td . * , u . * from Tutor_Details AS td JOIN Users as u on u.id_user = td.id_user LEFT JOIN Learning_Packs_Tag_Relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN Learning_Packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN Learning_Packs_Categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN Learning_Packs_Categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN Learning_Pack_Content as lpct on (lp.id_lp = lpct.id_lp) LEFT JOIN Webclasses_Tag_Relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN WebClasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN Learning_Packs_Categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN Learning_Packs_Categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN Order_Details as od on td.id_tutor = od.id_author LEFT JOIN Orders as o on od.id_order = o.id_order LEFT JOIN Tutors_Tag_Relations as ttagrels ON td.id_tutor = ttagrels.id_tutor JOIN Tags as t on (t.id_tag = ttagrels.id_tag) OR (t.id_tag = lptagrels.id_tag) OR (t.id_tag = wtagrels.id_tag) where (u.country='IE' or u.country IN ('INT')) AND CASE WHEN ((t.id_tag = lptagrels.id_tag) AND (lp.id_lp 0)) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND (lpcp.country_code='IE' or lpcp.country_code IN ('INT')) ELSE 1 END AND CASE WHEN ((t.id_tag = wtagrels.id_tag) AND (wc.id_wc 0)) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND (wccp.country_code='IE' or wccp.country_code IN ('INT')) ELSE 1 END AND CASE WHEN (od.id_od0) THEN od.id_author = td.id_tutor and o.order_status = 'paid' and CASE WHEN (od.id_wc 0) THEN od.can_attend_class=1 ELSE 1 END ELSE 1 END AND 1 group by td.id_tutor order by tutor_popularity desc, u.surname asc, u.name asc limit 0,20 Please note - The provided database structure does not show all the fields and tables as in this query

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• PHP statements, HTML and RSS

  - by poindexter

  Alrighty, I've got another little bit of code that I'm wrestling through. I'm building a conditional sidebar. The goal is to only show blog related stuff when posts in the "blog" category are being viewed. I've got part of it working, but the part where I'm trying to bring in an RSS feed of the category into the sidebar to show as recent posts. It doesn't work, and since I'm a php newb I'm not entirely sure why. Any suggestions or pointers are much appreciated. I'll post the problem section first, and then the entire php file second, so you all can see the context for the section that I'm having issues with. Problem Section: echo '<div class="panel iq-news">'; echo '<h4><span><a href="/category/blog/feed"><img src="/wp-content/themes/iq/images/rss-icon.gif" alt="Subscribe to our feed"/></a></span>IQNavigator Blog</h4>'; <?php query_posts('category_name=Blog&showposts=2'); if (have_posts()) : ?> echo '<ul>'; <?php while (have_posts()) : the_post(); ?> echo '<li><a href="<?php the_permalink();?>"><?php the_title();?> </a></li>'; <?php endwhile;?> echo '</ul>'; <?php endif;?> echo '<div class="twitter">'; echo '<p id="twitter-updates">'; <?php twitter_updates();?> echo '</p>'; echo '<p class="text-center"><a href="http://twitter.com/iqnavigator">Follow us on twitter</a></p>'; echo '</div>'; echo '</div>'; The whole darn long statement, for context reasons: <div class="sidebar"> <?php if (!is_search() && !is_page('Our Clients') && !is_archive()){ if($post->post_parent) { $children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0&depth=1&exclude=85,87,89,181,97,184"); } else { $children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0&depth=1&exclude=85,87,89,181,97,184"); } if ($children) { ?> <div class="panel links subnav"> <h3>In This Section</h3> <ul class="subnav"> <?php echo $children; ?> </ul> <p>&nbsp;</p> </div> <?php } } if(is_page('Our Clients') || in_category('Our Clients') || is_category('Our Clients')) { echo '<div class="panel links subnav">'; echo '<h3>In This Section</h3>'; echo '<ul class="subnav">'; wp_list_categories('child_of=21&title_li='); echo '</ul>'; echo '<p>&nbsp;</p>'; echo '</div>'; } else if (in_category('Blog')) { //PUT YOUR CODE HERE // echo get_page_content(34); echo '<div class="panel featured-resource">'; echo '<h4>Blog Contributors</h4>'; echo '<ul class"subnav">'; echo '<li><a href="/company/executive-team/john-f-martin/">John Martin</a></li>'; echo '<li><a href="/company/executive-team/kieran-brady/">Kieran Brady</a></li>'; echo '<li><a href="/company/executive-team/art-knapp/">Art Knapp</a></li>'; echo '</ul>'; echo '</div>'; echo '<div class="panel iq-news">'; echo '<h4><span><a href="/category/blog/feed"><img src="/wp-content/themes/iq/images/rss-icon.gif" alt="Subscribe to our feed"/></a></span>IQNavigator Blog</h4>'; <?php query_posts('category_name=Blog&showposts=2'); if (have_posts()) : ?> echo '<ul>'; <?php while (have_posts()) : the_post(); ?> echo '<li><a href="<?php the_permalink();?>"><?php the_title();?> </a></li>'; <?php endwhile;?> echo '</ul>'; <?php endif;?> echo '<div class="twitter">'; echo '<p id="twitter-updates">'; <?php twitter_updates();?> echo '</p>'; echo '<p class="text-center"><a href="http://twitter.com/iqnavigator">Follow us on twitter</a></p>'; echo '</div>'; echo '</div>'; //END CODE HERE } if (!is_page('Resources')) { ?> <div class="panel featured-resource"> <h4>Featured Resource</h4> <div class="embed"> <?php $custom_fields = get_post_custom(); $featured_video_code = $custom_fields['Featured Video Code']; if($featured_video_code) { foreach ( $featured_video_code as $key => $value ) { $the_code = $value; } $featured_video_link = $custom_fields['Featured Video Link']; foreach ( $featured_video_link as $key => $value ) { $the_link = $value; } $featured_video_text = $custom_fields['Featured Video Text']; foreach ( $featured_video_text as $key => $value ) { $the_text = $value; } if($the_code) { echo $the_code; } if($the_text) { echo '<ul>'; echo '<li>'; if($the_link) { echo '<a href="' . $the_link . '" class="video" target="_blank">' . $the_text . '</a>'; } else { echo $the_text; } echo '</li>'; echo '</ul>'; } } ?> + Visit Resource Center <div class="clr"></div> <div class="blue-bars"> <a href="<?php bloginfo('template_directory');?>/more-info.php" class="more-info" rel="facebox">Request More Info</a> <a href="<?php bloginfo('template_directory');?>/resource-form.php?id=701000000009E" class="view-demos" rel="facebox">Schedule a Demo</a> </div> </div> <div id="content">

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• change password code error

  - by ejah85

  I've created a code to change a password. Now it seem contain an error. When I fill in the form to change password, and click save the error message: Warning: mysql_real_escape_string() expects parameter 2 to be resource, null given in C:\Program Files\xampp\htdocs\e-Complaint(FYP)\userChangePass.php on line 103 Warning: mysql_real_escape_string() expects parameter 2 to be resource, null given in C:\Program Files\xampp\htdocs\e-Complaint(FYP)\userChangePass.php on line 103 I really don’t know what the error message means. Please guys. Help me fix it. Here's is the code: <?php session_start(); ?> <?php # change password.php //set the page title and include the html header. $page_title = 'Change Your Password'; //include('templates/header.inc'); if(isset($_POST['submit'])){//handle the form require_once('connectioncomplaint.php');//connect to the db. //include "connectioncomplaint.php"; //create a function for escaping the data. function escape_data($data){ global $dbc;//need the connection. if(ini_get('magic_quotes_gpc')){ $data=stripslashes($data); } return mysql_real_escape_string($data, $dbc); }//end function $message=NULL;//create the empty new variable. //check for a username if(empty($_POST['userid'])){ $u=FALSE; $message .='<p> You forgot enter your userid!</p>'; }else{ $u=escape_data($_POST['userid']); } //check for existing password if(empty($_POST['password'])){ $p=FALSE; $message .='<p>You forgot to enter your existing password!</p>'; }else{ $p=escape_data($_POST['password']); } //check for a password and match againts the comfirmed password. if(empty($_POST['password1'])) { $np=FALSE; $message .='<p> you forgot to enter your new password!</p>'; }else{ if($_POST['password1'] == $_POST['password2']){ $np=escape_data($_POST['password1']); }else{ $np=FALSE; $message .='<p> your new password did not match the confirmed new password!</p>'; } } if($u && $p && $np){//if everything's ok. $query="SELECT userid FROM access WHERE (userid='$u' AND password=PASSWORD('$p'))"; $result=@mysql_query($query); $num=mysql_num_rows($result); if($num == 1){ $row=mysql_fetch_array($result, MYSQL_NUM); //make the query $query="UPDATE access SET password=PASSWORD('$np') WHERE userid=$row[0]"; $result=@mysql_query($query);//run the query. if(mysql_affected_rows() == 1) {//if it run ok. //send an email,if desired. echo '<p><b>your password has been changed.</b></p>'; include('templates/footer.inc');//include the HTML footer. exit();//quit the script. }else{//if it did not run OK. $message= '<p>Your password could not be change due to a system error.We apolpgize for any inconvenience.</p><p>' .mysql_error() .'</p>'; } }else{ $message= '<p> Your username and password do not match our records.</p>'; } mysql_close();//close the database connection. }else{ $message .='<p>Please try again.</p>'; } }//end oh=f the submit conditional. //print the error message if there is one. if(isset($message)){ echo'<font color="red">' , $message, '</font>'; } ?> <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post"> <body> <script language="JavaScript1.2">mmLoadMenus();</script> <table width="604" height="599" border="0" align="center" cellpadding="0" cellspacing="0"> <tr> <td height="130" colspan="7"><img src="images/banner(E-Complaint)-.jpg" width="759" height="130" /></td> </tr> <tr> <td width="100" height="30" bgcolor="#ABD519"></td> <td width="100" bgcolor="#ABD519"></td> <td width="100" bgcolor="#ABD519"></td> <td width="100" bgcolor="#ABD519"></td> <td width="100" bgcolor="#ABD519"></td> <td width="160" bgcolor="#ABD519"> <?php include "header.php"; ?>&nbsp;</td> </tr> <tr> <td colspan="7" bgcolor="#FFFFFF"> <fieldset><legend> Enter your information in the form below:</legend> <p><b>User ID:</b> <input type="text" name="username" size="10" maxlength="20" value="<?php if(isset($_POST['userid'])) echo $_POST['userid']; ?>" /></p> <p><b>Current Password:</b> <input type="password" name="password" size="20" maxlength="20" /></p> <p><b>New Password:</b> <input type="password" name="password1" size="20" maxlength="20" /></p> <p><b>Confirm New Password:</b> <input type="password" name="password2" size="20" maxlength="20" /></p> </fieldset> <div align="center"> <input type="submit" name="submit" value="Change My Password" /></div> </form><!--End Form--> </td> </tr> </table> </body> </html>

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• AngularJS on top of ASP.NET: Moving the MVC framework out to the browser

  - by Varun Chatterji

  Heavily drawing inspiration from Ruby on Rails, MVC4’s convention over configuration model of development soon became the Holy Grail of .NET web development. The MVC model brought with it the goodness of proper separation of concerns between business logic, data, and the presentation logic. However, the MVC paradigm, was still one in which server side .NET code could be mixed with presentation code. The Razor templating engine, though cleaner than its predecessors, still encouraged and allowed you to mix .NET server side code with presentation logic. Thus, for example, if the developer required a certain <div> tag to be shown if a particular variable ShowDiv was true in the View’s model, the code could look like the following: Fig 1: To show a div or not. Server side .NET code is used in the View Mixing .NET code with HTML in views can soon get very messy. Wouldn’t it be nice if the presentation layer (HTML) could be pure HTML? Also, in the ASP.NET MVC model, some of the business logic invariably resides in the controller. It is tempting to use an anti­pattern like the one shown above to control whether a div should be shown or not. However, best practice would indicate that the Controller should not be aware of the div. The ShowDiv variable in the model should not exist. A controller should ideally, only be used to do the plumbing of getting the data populated in the model and nothing else. The view (ideally pure HTML) should render the presentation layer based on the model. In this article we will see how Angular JS, a new JavaScript framework by Google can be used effectively to build web applications where: 1. Views are pure HTML 2. Controllers (in the server sense) are pure REST based API calls 3. The presentation layer is loaded as needed from partial HTML only files. What is MVVM? MVVM short for Model View View Model is a new paradigm in web development. In this paradigm, the Model and View stuff exists on the client side through javascript instead of being processed on the server through postbacks. These frameworks are JavaScript frameworks that facilitate the clear separation of the “frontend” or the data rendering logic from the “backend” which is typically just a REST based API that loads and processes data through a resource model. The frameworks are called MVVM as a change to the Model (through javascript) gets reflected in the view immediately i.e. Model > View. Also, a change on the view (through manual input) gets reflected in the model immediately i.e. View > Model. The following figure shows this conceptually (comments are shown in red): Fig 2: Demonstration of MVVM in action In Fig 2, two text boxes are bound to the same variable model.myInt. Thus, changing the view manually (changing one text box through keyboard input) also changes the other textbox in real time demonstrating V > M property of a MVVM framework. Furthermore, clicking the button adds 1 to the value of model.myInt thus changing the model through JavaScript. This immediately updates the view (the value in the two textboxes) thus demonstrating the M > V property of a MVVM framework. Thus we see that the model in a MVVM JavaScript framework can be regarded as “the single source of truth“. This is an important concept. Angular is one such MVVM framework. We shall use it to build a simple app that sends SMS messages to a particular number. Application, Routes, Views, Controllers, Scope and Models Angular can be used in many ways to construct web applications. For this article, we shall only focus on building Single Page Applications (SPAs). Many of the approaches we will follow in this article have alternatives. It is beyond the scope of this article to explain every nuance in detail but we shall try to touch upon the basic concepts and end up with a working application that can be used to send SMS messages using Sent.ly Plus (a service that is itself built using Angular). Before you read on, we would like to urge you to forget what you know about Models, Views, Controllers and Routes in the ASP.NET MVC4 framework. All these words have different meanings in the Angular world. Whenever these words are used in this article, they will refer to Angular concepts and not ASP.NET MVC4 concepts. The following figure shows the skeleton of the root page of an SPA: Fig 3: The skeleton of a SPA The skeleton of the application is based on the Bootstrap starter template which can be found at: http://getbootstrap.com/examples/starter­template/ Apart from loading the Angular, jQuery and Bootstrap JavaScript libraries, it also loads our custom scripts /app/js/controllers.js /app/js/app.js These scripts define the routes, views and controllers which we shall come to in a moment. Application Notice that the body tag (Fig. 3) has an extra attribute: ng­app=”smsApp” Providing this tag “bootstraps” our single page application. It tells Angular to load a “module” called smsApp. This “module” is defined /app/js/app.js angular.module('smsApp', ['smsApp.controllers', function () {}]) Fig 4: The definition of our application module The line shows above, declares a module called smsApp. It also declares that this module “depends” on another module called “smsApp.controllers”. The smsApp.controllers module will contain all the controllers for our SPA. Routing and Views Notice that in the Navbar (in Fig 3) we have included two hyperlinks to: “#/app” “#/help” This is how Angular handles routing. Since the URLs start with “#”, they are actually just bookmarks (and not server side resources). However, our route definition (in /app/js/app.js) gives these URLs a special meaning within the Angular framework. angular.module('smsApp', ['smsApp.controllers', function () { }]) //Configure the routes .config(['$routeProvider', function ($routeProvider) { $routeProvider.when('/binding', { templateUrl: '/app/partials/bindingexample.html', controller: 'BindingController' }); }]); Fig 5: The definition of a route with an associated partial view and controller As we can see from the previous code sample, we are using the $routeProvider object in the configuration of our smsApp module. Notice how the code “asks for” the $routeProvider object by specifying it as a dependency in the [] braces and then defining a function that accepts it as a parameter. This is known as dependency injection. Please refer to the following link if you want to delve into this topic: http://docs.angularjs.org/guide/di What the above code snippet is doing is that it is telling Angular that when the URL is “#/binding”, then it should load the HTML snippet (“partial view”) found at /app/partials/bindingexample.html. Also, for this URL, Angular should load the controller called “BindingController”. We have also marked the div with the class “container” (in Fig 3) with the ng­view attribute. This attribute tells Angular that views (partial HTML pages) defined in the routes will be loaded within this div. You can see that the Angular JavaScript framework, unlike many other frameworks, works purely by extending HTML tags and attributes. It also allows you to extend HTML with your own tags and attributes (through directives) if you so desire, you can find out more about directives at the following URL: http://www.codeproject.com/Articles/607873/Extending­HTML­with­AngularJS­Directives Controllers and Models We have seen how we define what views and controllers should be loaded for a particular route. Let us now consider how controllers are defined. Our controllers are defined in the file /app/js/controllers.js. The following snippet shows the definition of the “BindingController” which is loaded when we hit the URL http://localhost:port/index.html#/binding (as we have defined in the route earlier as shown in Fig 5). Remember that we had defined that our application module “smsApp” depends on the “smsApp.controllers” module (see Fig 4). The code snippet below shows how the “BindingController” defined in the route shown in Fig 5 is defined in the module smsApp.controllers: angular.module('smsApp.controllers', [function () { }]) .controller('BindingController', ['$scope', function ($scope) { $scope.model = {}; $scope.model.myInt = 6; $scope.addOne = function () { $scope.model.myInt++; } }]); Fig 6: The definition of a controller in the “smsApp.controllers” module. The pieces are falling in place! Remember Fig.2? That was the code of a partial view that was loaded within the container div of the skeleton SPA shown in Fig 3. The route definition shown in Fig 5 also defined that the controller called “BindingController” (shown in Fig 6.) was loaded when we loaded the URL: http://localhost:22544/index.html#/binding The button in Fig 2 was marked with the attribute ng­click=”addOne()” which added 1 to the value of model.myInt. In Fig 6, we can see that this function is actually defined in the “BindingController”. Scope We can see from Fig 6, that in the definition of “BindingController”, we defined a dependency on $scope and then, as usual, defined a function which “asks for” $scope as per the dependency injection pattern. So what is $scope? Any guesses? As you might have guessed a scope is a particular “address space” where variables and functions may be defined. This has a similar meaning to scope in a programming language like C#. Model: The Scope is not the Model It is tempting to assign variables in the scope directly. For example, we could have defined myInt as $scope.myInt = 6 in Fig 6 instead of $scope.model.myInt = 6. The reason why this is a bad idea is that scope in hierarchical in Angular. Thus if we were to define a controller which was defined within the another controller (nested controllers), then the inner controller would inherit the scope of the parent controller. This inheritance would follow JavaScript prototypal inheritance. Let’s say the parent controller defined a variable through $scope.myInt = 6. The child controller would inherit the scope through java prototypical inheritance. This basically means that the child scope has a variable myInt that points to the parent scopes myInt variable. Now if we assigned the value of myInt in the parent, the child scope would be updated with the same value as the child scope’s myInt variable points to the parent scope’s myInt variable. However, if we were to assign the value of the myInt variable in the child scope, then the link of that variable to the parent scope would be broken as the variable myInt in the child scope now points to the value 6 and not to the parent scope’s myInt variable. But, if we defined a variable model in the parent scope, then the child scope will also have a variable model that points to the model variable in the parent scope. Updating the value of $scope.model.myInt in the parent scope would change the model variable in the child scope too as the variable is pointed to the model variable in the parent scope. Now changing the value of $scope.model.myInt in the child scope would ALSO change the value in the parent scope. This is because the model reference in the child scope is pointed to the scope variable in the parent. We did no new assignment to the model variable in the child scope. We only changed an attribute of the model variable. Since the model variable (in the child scope) points to the model variable in the parent scope, we have successfully changed the value of myInt in the parent scope. Thus the value of $scope.model.myInt in the parent scope becomes the “single source of truth“. This is a tricky concept, thus it is considered good practice to NOT use scope inheritance. More info on prototypal inheritance in Angular can be found in the “JavaScript Prototypal Inheritance” section at the following URL: https://github.com/angular/angular.js/wiki/Understanding­Scopes. Building It: An Angular JS application using a .NET Web API Backend Now that we have a perspective on the basic components of an MVVM application built using Angular, let’s build something useful. We will build an application that can be used to send out SMS messages to a given phone number. The following diagram describes the architecture of the application we are going to build: Fig 7: Broad application architecture We are going to add an HTML Partial to our project. This partial will contain the form fields that will accept the phone number and message that needs to be sent as an SMS. It will also display all the messages that have previously been sent. All the executable code that is run on the occurrence of events (button clicks etc.) in the view resides in the controller. The controller interacts with the ASP.NET WebAPI to get a history of SMS messages, add a message etc. through a REST based API. For the purposes of simplicity, we will use an in memory data structure for the purposes of creating this application. Thus, the tasks ahead of us are: Creating the REST WebApi with GET, PUT, POST, DELETE methods. Creating the SmsView.html partial Creating the SmsController controller with methods that are called from the SmsView.html partial Add a new route that loads the controller and the partial. 1. Creating the REST WebAPI This is a simple task that should be quite straightforward to any .NET developer. The following listing shows our ApiController: public class SmsMessage { public string to { get; set; } public string message { get; set; } } public class SmsResource : SmsMessage { public int smsId { get; set; } } public class SmsResourceController : ApiController { public static Dictionary<int, SmsResource> messages = new Dictionary<int, SmsResource>(); public static int currentId = 0; // GET api/<controller> public List<SmsResource> Get() { List<SmsResource> result = new List<SmsResource>(); foreach (int key in messages.Keys) { result.Add(messages[key]); } return result; } // GET api/<controller>/5 public SmsResource Get(int id) { if (messages.ContainsKey(id)) return messages[id]; return null; } // POST api/<controller> public List<SmsResource> Post([FromBody] SmsMessage value) { //Synchronize on messages so we don't have id collisions lock (messages) { SmsResource res = (SmsResource) value; res.smsId = currentId++; messages.Add(res.smsId, res); //SentlyPlusSmsSender.SendMessage(value.to, value.message); return Get(); } } // PUT api/<controller>/5 public List<SmsResource> Put(int id, [FromBody] SmsMessage value) { //Synchronize on messages so we don't have id collisions lock (messages) { if (messages.ContainsKey(id)) { //Update the message messages[id].message = value.message; messages[id].to = value.message; } return Get(); } } // DELETE api/<controller>/5 public List<SmsResource> Delete(int id) { if (messages.ContainsKey(id)) { messages.Remove(id); } return Get(); } } Once this class is defined, we should be able to access the WebAPI by a simple GET request using the browser: http://localhost:port/api/SmsResource Notice the commented line: //SentlyPlusSmsSender.SendMessage The SentlyPlusSmsSender class is defined in the attached solution. We have shown this line as commented as we want to explain the core Angular concepts. If you load the attached solution, this line is uncommented in the source and an actual SMS will be sent! By default, the API returns XML. For consumption of the API in Angular, we would like it to return JSON. To change the default to JSON, we make the following change to WebApiConfig.cs file located in the App_Start folder. public static class WebApiConfig { public static void Register(HttpConfiguration config) { config.Routes.MapHttpRoute( name: "DefaultApi", routeTemplate: "api/{controller}/{id}", defaults: new { id = RouteParameter.Optional } ); var appXmlType = config.Formatters.XmlFormatter. SupportedMediaTypes. FirstOrDefault( t => t.MediaType == "application/xml"); config.Formatters.XmlFormatter.SupportedMediaTypes.Remove(appXmlType); } } We now have our backend REST Api which we can consume from Angular! 2. Creating the SmsView.html partial This simple partial will define two fields: the destination phone number (international format starting with a +) and the message. These fields will be bound to model.phoneNumber and model.message. We will also add a button that we shall hook up to sendMessage() in the controller. A list of all previously sent messages (bound to model.allMessages) will also be displayed below the form input. The following code shows the code for the partial: <!--­­ If model.errorMessage is defined, then render the error div -­­> <div class="alert alert-­danger alert-­dismissable" style="margin­-top: 30px;" ng­-show="model.errorMessage != undefined"> <button type="button" class="close" data­dismiss="alert" aria­hidden="true">&times;</button> <strong>Error!</strong> <br /> {{ model.errorMessage }} </div> <!--­­ The input fields bound to the model --­­> <div class="well" style="margin-­top: 30px;"> <table style="width: 100%;"> <tr> <td style="width: 45%; text-­align: center;"> <input type="text" placeholder="Phone number (eg; +44 7778 609466)" ng­-model="model.phoneNumber" class="form-­control" style="width: 90%" onkeypress="return checkPhoneInput();" /> </td> <td style="width: 45%; text-­align: center;"> <input type="text" placeholder="Message" ng­-model="model.message" class="form-­control" style="width: 90%" /> </td> <td style="text-­align: center;"> <button class="btn btn-­danger" ng-­click="sendMessage();" ng-­disabled="model.isAjaxInProgress" style="margin­right: 5px;">Send</button> <img src="/Content/ajax-­loader.gif" ng­-show="model.isAjaxInProgress" /> </td> </tr> </table> </div> <!--­­ The past messages ­­--> <div style="margin-­top: 30px;"> <!­­-- The following div is shown if there are no past messages --­­> <div ng­-show="model.allMessages.length == 0"> No messages have been sent yet! </div> <!--­­ The following div is shown if there are some past messages --­­> <div ng-­show="model.allMessages.length == 0"> <table style="width: 100%;" class="table table-­striped"> <tr> <td>Phone Number</td> <td>Message</td> <td></td> </tr> <!--­­ The ng-­repeat directive is line the repeater control in .NET, but as you can see this partial is pure HTML which is much cleaner --> <tr ng-­repeat="message in model.allMessages"> <td>{{ message.to }}</td> <td>{{ message.message }}</td> <td> <button class="btn btn-­danger" ng-­click="delete(message.smsId);" ng­-disabled="model.isAjaxInProgress">Delete</button> </td> </tr> </table> </div> </div> The above code is commented and should be self explanatory. Conditional rendering is achieved through using the ng-­show=”condition” attribute on various div tags. Input fields are bound to the model and the send button is bound to the sendMessage() function in the controller as through the ng­click=”sendMessage()” attribute defined on the button tag. While AJAX calls are taking place, the controller sets model.isAjaxInProgress to true. Based on this variable, buttons are disabled through the ng-­disabled directive which is added as an attribute to the buttons. The ng-­repeat directive added as an attribute to the tr tag causes the table row to be rendered multiple times much like an ASP.NET repeater. 3. Creating the SmsController controller The penultimate piece of our application is the controller which responds to events from our view and interacts with our MVC4 REST WebAPI. The following listing shows the code we need to add to /app/js/controllers.js. Note that controller definitions can be chained. Also note that this controller “asks for” the $http service. The $http service is a simple way in Angular to do AJAX. So far we have only encountered modules, controllers, views and directives in Angular. The $http is new entity in Angular called a service. More information on Angular services can be found at the following URL: http://docs.angularjs.org/guide/dev_guide.services.understanding_services. .controller('SmsController', ['$scope', '$http', function ($scope, $http) { //We define the model $scope.model = {}; //We define the allMessages array in the model //that will contain all the messages sent so far $scope.model.allMessages = []; //The error if any $scope.model.errorMessage = undefined; //We initially load data so set the isAjaxInProgress = true; $scope.model.isAjaxInProgress = true; //Load all the messages $http({ url: '/api/smsresource', method: "GET" }). success(function (data, status, headers, config) { this callback will be called asynchronously //when the response is available $scope.model.allMessages = data; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }). error(function (data, status, headers, config) { //called asynchronously if an error occurs //or server returns response with an error status. $scope.model.errorMessage = "Error occurred status:" + status; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); $scope.delete = function (id) { //We are making an ajax call so we set this to true $scope.model.isAjaxInProgress = true; $http({ url: '/api/smsresource/' + id, method: "DELETE" }). success(function (data, status, headers, config) { // this callback will be called asynchronously // when the response is available $scope.model.allMessages = data; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); error(function (data, status, headers, config) { // called asynchronously if an error occurs // or server returns response with an error status. $scope.model.errorMessage = "Error occurred status:" + status; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); } $scope.sendMessage = function () { $scope.model.errorMessage = undefined; var message = ''; if($scope.model.message != undefined) message = $scope.model.message.trim(); if ($scope.model.phoneNumber == undefined || $scope.model.phoneNumber == '' || $scope.model.phoneNumber.length < 10 || $scope.model.phoneNumber[0] != '+') { $scope.model.errorMessage = "You must enter a valid phone number in international format. Eg: +44 7778 609466"; return; } if (message.length == 0) { $scope.model.errorMessage = "You must specify a message!"; return; } //We are making an ajax call so we set this to true $scope.model.isAjaxInProgress = true; $http({ url: '/api/smsresource', method: "POST", data: { to: $scope.model.phoneNumber, message: $scope.model.message } }). success(function (data, status, headers, config) { // this callback will be called asynchronously // when the response is available $scope.model.allMessages = data; //We are done with AJAX loading $scope.model.isAjaxInProgress = false; }). error(function (data, status, headers, config) { // called asynchronously if an error occurs // or server returns response with an error status. $scope.model.errorMessage = "Error occurred status:" + status // We are done with AJAX loading $scope.model.isAjaxInProgress = false; }); } }]); We can see from the previous listing how the functions that are called from the view are defined in the controller. It should also be evident how easy it is to make AJAX calls to consume our MVC4 REST WebAPI. Now we are left with the final piece. We need to define a route that associates a particular path with the view we have defined and the controller we have defined. 4. Add a new route that loads the controller and the partial This is the easiest part of the puzzle. We simply define another route in the /app/js/app.js file: $routeProvider.when('/sms', { templateUrl: '/app/partials/smsview.html', controller: 'SmsController' }); Conclusion In this article we have seen how much of the server side functionality in the MVC4 framework can be moved to the browser thus delivering a snappy and fast user interface. We have seen how we can build client side HTML only views that avoid the messy syntax offered by server side Razor views. We have built a functioning app from the ground up. The significant advantage of this approach to building web apps is that the front end can be completely platform independent. Even though we used ASP.NET to create our REST API, we could just easily have used any other language such as Node.js, Ruby etc without changing a single line of our front end code. Angular is a rich framework and we have only touched on basic functionality required to create a SPA. For readers who wish to delve further into the Angular framework, we would recommend the following URL as a starting point: http://docs.angularjs.org/misc/started. To get started with the code for this project: Sign up for an account at http://plus.sent.ly (free) Add your phone number Go to the “My Identies Page” Note Down your Sender ID, Consumer Key and Consumer Secret Download the code for this article at: https://docs.google.com/file/d/0BzjEWqSE31yoZjZlV0d0R2Y3eW8/edit?usp=sharing Change the values of Sender Id, Consumer Key and Consumer Secret in the web.config file Run the project through Visual Studio!

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• Using HTML 5 SessionState to save rendered Page Content

  - by Rick Strahl

  HTML 5 SessionState and LocalStorage are very useful and super easy to use to manage client side state. For building rich client side or SPA style applications it's a vital feature to be able to cache user data as well as HTML content in order to swap pages in and out of the browser's DOM. What might not be so obvious is that you can also use the sessionState and localStorage objects even in classic server rendered HTML applications to provide caching features between pages. These APIs have been around for a long time and are supported by most relatively modern browsers and even all the way back to IE8, so you can use them safely in your Web applications. SessionState and LocalStorage are easy The APIs that make up sessionState and localStorage are very simple. Both object feature the same API interface which  is a simple, string based key value store that has getItem, setItem, removeitem, clear and  key methods. The objects are also pseudo array objects and so can be iterated like an array with  a length property and you have array indexers to set and get values with. Basic usage  for storing and retrieval looks like this (using sessionStorage, but the syntax is the same for localStorage - just switch the objects):// set var lastAccess = new Date().getTime(); if (sessionStorage) sessionStorage.setItem("myapp_time", lastAccess.toString()); // retrieve in another page or on a refresh var time = null; if (sessionStorage) time = sessionStorage.getItem("myapp_time"); if (time) time = new Date(time * 1); else time = new Date(); sessionState stores data that is browser session specific and that has a liftetime of the active browser session or window. Shut down the browser or tab and the storage goes away. localStorage uses the same API interface, but the lifetime of the data is permanently stored in the browsers storage area until deleted via code or by clearing out browser cookies (not the cache). Both sessionStorage and localStorage space is limited. The spec is ambiguous about this - supposedly sessionStorage should allow for unlimited size, but it appears that most WebKit browsers support only 2.5mb for either object. This means you have to be careful what you store especially since other applications might be running on the same domain and also use the storage mechanisms. That said 2.5mb worth of character data is quite a bit and would go a long way. The easiest way to get a feel for how sessionState and localStorage work is to look at a simple example. You can go check out the following example online in Plunker: http://plnkr.co/edit/0ICotzkoPjHaWa70GlRZ?p=preview which looks like this: Plunker is an online HTML/JavaScript editor that lets you write and run Javascript code and similar to JsFiddle, but a bit cleaner to work in IMHO (thanks to John Papa for turning me on to it). The sample has two text boxes with counts that update session/local storage every time you click the related button. The counts are 'cached' in Session and Local storage. The point of these examples is that both counters survive full page reloads, and the LocalStorage counter survives a complete browser shutdown and restart. Go ahead and try it out by clicking the Reload button after updating both counters and then shutting down the browser completely and going back to the same URL (with the same browser). What you should see is that reloads leave both counters intact at the counted values, while a browser restart will leave only the local storage counter intact. The code to deal with the SessionStorage (and LocalStorage not shown here) in the example is isolated into a couple of wrapper methods to simplify the code: function getSessionCount() { var count = 0; if (sessionStorage) { var count = sessionStorage.getItem("ss_count"); count = !count ? 0 : count * 1; } $("#txtSession").val(count); return count; } function setSessionCount(count) { if (sessionStorage) sessionStorage.setItem("ss_count", count.toString()); } These two functions essentially load and store a session counter value. The two key methods used here are: sessionStorage.getItem(key); sessionStorage.setItem(key,stringVal); Note that the value given to setItem and return by getItem has to be a string. If you pass another type you get an error. Don't let that limit you though - you can easily enough store JSON data in a variable so it's quite possible to pass complex objects and store them into a single sessionStorage value:var user = { name: "Rick", id="ricks", level=8 } sessionStorage.setItem("app_user",JSON.stringify(user)); to retrieve it:var user = sessionStorage.getItem("app_user"); if (user) user = JSON.parse(user); Simple! If you're using the Chrome Developer Tools (F12) you can also check out the session and local storage state on the Resource tab:   You can also use this tool to refresh or remove entries from storage. What we just looked at is a purely client side implementation where a couple of counters are stored. For rich client centric AJAX applications sessionStorage and localStorage provide a very nice and simple API to store application state while the application is running. But you can also use these storage mechanisms to manage server centric HTML applications when you combine server rendering with some JavaScript to perform client side data caching. You can both store some state information and data on the client (ie. store a JSON object and carry it forth between server rendered HTML requests) or you can use it for good old HTTP based caching where some rendered HTML is saved and then restored later. Let's look at the latter with a real life example. Why do I need Client-side Page Caching for Server Rendered HTML? I don't know about you, but in a lot of my existing server driven applications I have lists that display a fair amount of data. Typically these lists contain links to then drill down into more specific data either for viewing or editing. You can then click on a link and go off to a detail page that provides more concise content. So far so good. But now you're done with the detail page and need to get back to the list, so you click on a 'bread crumbs trail' or an application level 'back to list' button and… …you end up back at the top of the list - the scroll position, the current selection in some cases even filters conditions - all gone with the wind. You've left behind the state of the list and are starting from scratch in your browsing of the list from the top. Not cool! Sound familiar? This a pretty common scenario with server rendered HTML content where it's so common to display lists to drill into, only to lose state in the process of returning back to the original list. Look at just about any traditional forums application, or even StackOverFlow to see what I mean here. Scroll down a bit to look at a post or entry, drill in then use the bread crumbs or tab to go back… In some cases returning to the top of a list is not a big deal. On StackOverFlow that sort of works because content is turning around so quickly you probably want to actually look at the top posts. Not always though - if you're browsing through a list of search topics you're interested in and drill in there's no way back to that position. Essentially anytime you're actively browsing the items in the list, that's when state becomes important and if it's not handled the user experience can be really disrupting. Content Caching If you're building client centric SPA style applications this is a fairly easy to solve problem - you tend to render the list once and then update the page content to overlay the detail content, only hiding the list temporarily until it's used again later. It's relatively easy to accomplish this simply by hiding content on the page and later making it visible again. But if you use server rendered content, hanging on to all the detail like filters, selections and scroll position is not quite as easy. Or is it??? This is where sessionStorage comes in handy. What if we just save the rendered content of a previous page, and then restore it when we return to this page based on a special flag that tells us to use the cached version? Let's see how we can do this. A real World Use Case Recently my local ISP asked me to help out with updating an ancient classifieds application. They had a very busy, local classifieds app that was originally an ASP classic application. The old app was - wait for it: frames based - and even though I lobbied against it, the decision was made to keep the frames based layout to allow rapid browsing of the hundreds of posts that are made on a daily basis. The primary reason they wanted this was precisely for the ability to quickly browse content item by item. While I personally hate working with Frames, I have to admit that the UI actually works well with the frames layout as long as you're running on a large desktop screen. You can check out the frames based desktop site here: http://classifieds.gorge.net/ However when I rebuilt the app I also added a secondary view that doesn't use frames. The main reason for this of course was for mobile displays which work horribly with frames. So there's a somewhat mobile friendly interface to the interface, which ditches the frames and uses some responsive design tweaking for mobile capable operation: http://classifeds.gorge.net/mobile  (or browse the base url with your browser width under 800px)   Here's what the mobile, non-frames view looks like:   As you can see this means that the list of classifieds posts now is a list and there's a separate page for drilling down into the item. And of course… originally we ran into that usability issue I mentioned earlier where the browse, view detail, go back to the list cycle resulted in lost list state. Originally in mobile mode you scrolled through the list, found an item to look at and drilled in to display the item detail. Then you clicked back to the list and BAM - you've lost your place. Because there are so many items added on a daily basis the full list is never fully loaded, but rather there's a "Load Additional Listings"  entry at the button. Not only did we originally lose our place when coming back to the list, but any 'additionally loaded' items are no longer there because the list was now rendering  as if it was the first page hit. The additional listings, and any filters, the selection of an item all were lost. Major Suckage! Using Client SessionStorage to cache Server Rendered Content To work around this problem I decided to cache the rendered page content from the list in SessionStorage. Anytime the list renders or is updated with Load Additional Listings, the page HTML is cached and stored in Session Storage. Any back links from the detail page or the login or write entry forms then point back to the list page with a back=true query string parameter. If the server side sees this parameter it doesn't render the part of the page that is cached. Instead the client side code retrieves the data from the sessionState cache and simply inserts it into the page. It sounds pretty simple, and the overall the process is really easy, but there are a few gotchas that I'll discuss in a minute. But first let's look at the implementation. Let's start with the server side here because that'll give a quick idea of the doc structure. As I mentioned the server renders data from an ASP.NET MVC view. On the list page when returning to the list page from the display page (or a host of other pages) looks like this: https://classifieds.gorge.net/list?back=True The query string value is a flag, that indicates whether the server should render the HTML. Here's what the top level MVC Razor view for the list page looks like:@model MessageListViewModel @{ ViewBag.Title = "Classified Listing"; bool isBack = !string.IsNullOrEmpty(Request.QueryString["back"]); } <form method="post" action="@Url.Action("list")"> <div id="SizingContainer"> @if (!isBack) { @Html.Partial("List_CommandBar_Partial", Model) <div id="PostItemContainer" class="scrollbox" xstyle="-webkit-overflow-scrolling: touch;"> @Html.Partial("List_Items_Partial", Model) @if (Model.RequireLoadEntry) { <div class="postitem loadpostitems" style="padding: 15px;"> <div id="LoadProgress" class="smallprogressright"></div> <div class="control-progress"> Load additional listings... </div> </div> } </div> } </div> </form> As you can see the query string triggers a conditional block that if set is simply not rendered. The content inside of #SizingContainer basically holds  the entire page's HTML sans the headers and scripts, but including the filter options and menu at the top. In this case this makes good sense - in other situations the fact that the menu or filter options might be dynamically updated might make you only cache the list rather than essentially the entire page. In this particular instance all of the content works and produces the proper result as both the list along with any filter conditions in the form inputs are restored. Ok, let's move on to the client. On the client there are two page level functions that deal with saving and restoring state. Like the counter example I showed earlier, I like to wrap the logic to save and restore values from sessionState into a separate function because they are almost always used in several places.page.saveData = function(id) { if (!sessionStorage) return; var data = { id: id, scroll: $("#PostItemContainer").scrollTop(), html: $("#SizingContainer").html() }; sessionStorage.setItem("list_html",JSON.stringify(data)); }; page.restoreData = function() { if (!sessionStorage) return; var data = sessionStorage.getItem("list_html"); if (!data) return null; return JSON.parse(data); }; The data that is saved is an object which contains an ID which is the selected element when the user clicks and a scroll position. These two values are used to reset the scroll position when the data is used from the cache. Finally the html from the #SizingContainer element is stored, which makes for the bulk of the document's HTML. In this application the HTML captured could be a substantial bit of data. If you recall, I mentioned that the server side code renders a small chunk of data initially and then gets more data if the user reads through the first 50 or so items. The rest of the items retrieved can be rather sizable. Other than the JSON deserialization that's Ok. Since I'm using SessionStorage the storage space has no immediate limits. Next is the core logic to handle saving and restoring the page state. At first though this would seem pretty simple, and in some cases it might be, but as the following code demonstrates there are a few gotchas to watch out for. Here's the relevant code I use to save and restore:$( function() { … var isBack = getUrlEncodedKey("back", location.href); if (isBack) { // remove the back key from URL setUrlEncodedKey("back", "", location.href); var data = page.restoreData(); // restore from sessionState if (!data) { // no data - force redisplay of the server side default list window.location = "list"; return; } $("#SizingContainer").html(data.html); var el = $(".postitem[data-id=" + data.id + "]"); $(".postitem").removeClass("highlight"); el.addClass("highlight"); $("#PostItemContainer").scrollTop(data.scroll); setTimeout(function() { el.removeClass("highlight"); }, 2500); } else if (window.noFrames) page.saveData(null); // save when page loads $("#SizingContainer").on("click", ".postitem", function() { var id = $(this).attr("data-id"); if (!id) return true; if (window.noFrames) page.saveData(id); var contentFrame = window.parent.frames["Content"]; if (contentFrame) contentFrame.location.href = "show/" + id; else window.location.href = "show/" + id; return false; }); … The code starts out by checking for the back query string flag which triggers restoring from the client cache. If cached the cached data structure is read from sessionStorage. It's important here to check if data was returned. If the user had back=true on the querystring but there is no cached data, he likely bookmarked this page or otherwise shut down the browser and came back to this URL. In that case the server didn't render any detail and we have no cached data, so all we can do is redirect to the original default list view using window.location. If we continued the page would render no data - so make sure to always check the cache retrieval result. Always! If there is data the it's loaded and the data.html data is restored back into the document by simply injecting the HTML back into the document's #SizingContainer element:$("#SizingContainer").html(data.html); It's that simple and it's quite quick even with a fully loaded list of additional items and on a phone. The actual HTML data is stored to the cache on every page load initially and then again when the user clicks on an element to navigate to a particular listing. The former ensures that the client cache always has something in it, and the latter updates with additional information for the selected element. For the click handling I use a data-id attribute on the list item (.postitem) in the list and retrieve the id from that. That id is then used to navigate to the actual entry as well as storing that Id value in the saved cached data. The id is used to reset the selection by searching for the data-id value in the restored elements. The overall process of this save/restore process is pretty straight forward and it doesn't require a bunch of code, yet it yields a huge improvement in the usability of the site on mobile devices (or anybody who uses the non-frames view). Some things to watch out for As easy as it conceptually seems to simply store and retrieve cached content, you have to be quite aware what type of content you are caching. The code above is all that's specific to cache/restore cycle and it works, but it took a few tweaks to the rest of the script code and server code to make it all work. There were a few gotchas that weren't immediately obvious. Here are a few things to pay attention to: Event Handling Logic Timing of manipulating DOM events Inline Script Code Bookmarking to the Cache Url when no cache exists Do you have inline script code in your HTML? That script code isn't going to run if you restore from cache and simply assign or it may not run at the time you think it would normally in the DOM rendering cycle. JavaScript Event Hookups The biggest issue I ran into with this approach almost immediately is that originally I had various static event handlers hooked up to various UI elements that are now cached. If you have an event handler like:$("#btnSearch").click( function() {…}); that works fine when the page loads with server rendered HTML, but that code breaks when you now load the HTML from cache. Why? Because the elements you're trying to hook those events to may not actually be there - yet. Luckily there's an easy workaround for this by using deferred events. With jQuery you can use the .on() event handler instead:$("#SelectionContainer").on("click","#btnSearch", function() {…}); which monitors a parent element for the events and checks for the inner selector elements to handle events on. This effectively defers to runtime event binding, so as more items are added to the document bindings still work. For any cached content use deferred events. Timing of manipulating DOM Elements Along the same lines make sure that your DOM manipulation code follows the code that loads the cached content into the page so that you don't manipulate DOM elements that don't exist just yet. Ideally you'll want to check for the condition to restore cached content towards the top of your script code, but that can be tricky if you have components or other logic that might not all run in a straight line. Inline Script Code Here's another small problem I ran into: I use a DateTime Picker widget I built a while back that relies on the jQuery date time picker. I also created a helper function that allows keyboard date navigation into it that uses JavaScript logic. Because MVC's limited 'object model' the only way to embed widget content into the page is through inline script. This code broken when I inserted the cached HTML into the page because the script code was not available when the component actually got injected into the page. As the last bullet - it's a matter of timing. There's no good work around for this - in my case I pulled out the jQuery date picker and relied on native <input type="date" /> logic instead - a better choice these days anyway, especially since this view is meant to be primarily to serve mobile devices which actually support date input through the browser (unlike desktop browsers of which only WebKit seems to support it). Bookmarking Cached Urls When you cache HTML content you have to make a decision whether you cache on the client and also not render that same content on the server. In the Classifieds app I didn't render server side content so if the user comes to the page with back=True and there is no cached content I have to a have a Plan B. Typically this happens when somebody ends up bookmarking the back URL. The easiest and safest solution for this scenario is to ALWAYS check the cache result to make sure it exists and if not have a safe URL to go back to - in this case to the plain uncached list URL which amounts to effectively redirecting. This seems really obvious in hindsight, but it's easy to overlook and not see a problem until much later, when it's not obvious at all why the page is not rendering anything. Don't use <body> to replace Content Since we're practically replacing all the HTML in the page it may seem tempting to simply replace the HTML content of the <body> tag. Don't. The body tag usually contains key things that should stay in the page and be there when it loads. Specifically script tags and elements and possibly other embedded content. It's best to create a top level DOM element specifically as a placeholder container for your cached content and wrap just around the actual content you want to replace. In the app above the #SizingContainer is that container. Other Approaches The approach I've used for this application is kind of specific to the existing server rendered application we're running and so it's just one approach you can take with caching. However for server rendered content caching this is a pattern I've used in a few apps to retrofit some client caching into list displays. In this application I took the path of least resistance to the existing server rendering logic. Here are a few other ways that come to mind: Using Partial HTML Rendering via AJAXInstead of rendering the page initially on the server, the page would load empty and the client would render the UI by retrieving the respective HTML and embedding it into the page from a Partial View. This effectively makes the initial rendering and the cached rendering logic identical and removes the server having to decide whether this request needs to be rendered or not (ie. not checking for a back=true switch). All the logic related to caching is made on the client in this case. Using JSON Data and Client RenderingThe hardcore client option is to do the whole UI SPA style and pull data from the server and then use client rendering or databinding to pull the data down and render using templates or client side databinding with knockout/angular et al. As with the Partial Rendering approach the advantage is that there's no difference in the logic between pulling the data from cache or rendering from scratch other than the initial check for the cache request. Of course if the app is a  full on SPA app, then caching may not be required even - the list could just stay in memory and be hidden and reactivated. I'm sure there are a number of other ways this can be handled as well especially using  AJAX. AJAX rendering might simplify the logic, but it also complicates search engine optimization since there's no content loaded initially. So there are always tradeoffs and it's important to look at all angles before deciding on any sort of caching solution in general. State of the Session SessionState and LocalStorage are easy to use in client code and can be integrated even with server centric applications to provide nice caching features of content and data. In this post I've shown a very specific scenario of storing HTML content for the purpose of remembering list view data and state and making the browsing experience for lists a bit more friendly, especially if there's dynamically loaded content involved. If you haven't played with sessionStorage or localStorage I encourage you to give it a try. There's a lot of cool stuff that you can do with this beyond the specific scenario I've covered here… Resources Overview of localStorage (also applies to sessionStorage) Web Storage Compatibility Modernizr Test Suite© Rick Strahl, West Wind Technologies, 2005-2013Posted in JavaScript  HTML5  ASP.NET  MVC   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• value types in the vm

  - by john.rose

  value types in the vm p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} p.p2 {margin: 0.0px 0.0px 14.0px 0.0px; font: 14.0px Times} p.p3 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times} p.p4 {margin: 0.0px 0.0px 15.0px 0.0px; font: 14.0px Times} p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier} p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Courier; min-height: 17.0px} p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p8 {margin: 0.0px 0.0px 0.0px 36.0px; text-indent: -36.0px; font: 14.0px Times; min-height: 18.0px} p.p9 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; min-height: 18.0px} p.p10 {margin: 0.0px 0.0px 12.0px 0.0px; font: 14.0px Times; color: #000000} li.li1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times} li.li7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 14.0px Times; min-height: 18.0px} span.s1 {font: 14.0px Courier} span.s2 {color: #000000} span.s3 {font: 14.0px Courier; color: #000000} ol.ol1 {list-style-type: decimal} Or, enduring values for a changing world. Introduction A value type is a data type which, generally speaking, is designed for being passed by value in and out of methods, and stored by value in data structures. The only value types which the Java language directly supports are the eight primitive types. Java indirectly and approximately supports value types, if they are implemented in terms of classes. For example, both Integer and String may be viewed as value types, especially if their usage is restricted to avoid operations appropriate to Object. In this note, we propose a definition of value types in terms of a design pattern for Java classes, accompanied by a set of usage restrictions. We also sketch the relation of such value types to tuple types (which are a JVM-level notion), and point out JVM optimizations that can apply to value types. This note is a thought experiment to extend the JVM’s performance model in support of value types. The demonstration has two phases.  Initially the extension can simply use design patterns, within the current bytecode architecture, and in today’s Java language. But if the performance model is to be realized in practice, it will probably require new JVM bytecode features, changes to the Java language, or both.  We will look at a few possibilities for these new features. An Axiom of Value In the context of the JVM, a value type is a data type equipped with construction, assignment, and equality operations, and a set of typed components, such that, whenever two variables of the value type produce equal corresponding values for their components, the values of the two variables cannot be distinguished by any JVM operation. Here are some corollaries: A value type is immutable, since otherwise a copy could be constructed and the original could be modified in one of its components, allowing the copies to be distinguished. Changing the component of a value type requires construction of a new value. The equals and hashCode operations are strictly component-wise. If a value type is represented by a JVM reference, that reference cannot be successfully synchronized on, and cannot be usefully compared for reference equality. A value type can be viewed in terms of what it doesn’t do. We can say that a value type omits all value-unsafe operations, which could violate the constraints on value types.  These operations, which are ordinarily allowed for Java object types, are pointer equality comparison (the acmp instruction), synchronization (the monitor instructions), all the wait and notify methods of class Object, and non-trivial finalize methods. The clone method is also value-unsafe, although for value types it could be treated as the identity function. Finally, and most importantly, any side effect on an object (however visible) also counts as an value-unsafe operation. A value type may have methods, but such methods must not change the components of the value. It is reasonable and useful to define methods like toString, equals, and hashCode on value types, and also methods which are specifically valuable to users of the value type. Representations of Value Value types have two natural representations in the JVM, unboxed and boxed. An unboxed value consists of the components, as simple variables. For example, the complex number x=(1+2i), in rectangular coordinate form, may be represented in unboxed form by the following pair of variables: /*Complex x = Complex.valueOf(1.0, 2.0):*/ double x_re = 1.0, x_im = 2.0; These variables might be locals, parameters, or fields. Their association as components of a single value is not defined to the JVM. Here is a sample computation which computes the norm of the difference between two complex numbers: double distance(/*Complex x:*/ double x_re, double x_im,         /*Complex y:*/ double y_re, double y_im) {     /*Complex z = x.minus(y):*/     double z_re = x_re - y_re, z_im = x_im - y_im;     /*return z.abs():*/     return Math.sqrt(z_re*z_re + z_im*z_im); } A boxed representation groups component values under a single object reference. The reference is to a ‘wrapper class’ that carries the component values in its fields. (A primitive type can naturally be equated with a trivial value type with just one component of that type. In that view, the wrapper class Integer can serve as a boxed representation of value type int.) The unboxed representation of complex numbers is practical for many uses, but it fails to cover several major use cases: return values, array elements, and generic APIs. The two components of a complex number cannot be directly returned from a Java function, since Java does not support multiple return values. The same story applies to array elements: Java has no ’array of structs’ feature. (Double-length arrays are a possible workaround for complex numbers, but not for value types with heterogeneous components.) By generic APIs I mean both those which use generic types, like Arrays.asList and those which have special case support for primitive types, like String.valueOf and PrintStream.println. Those APIs do not support unboxed values, and offer some problems to boxed values. Any ’real’ JVM type should have a story for returns, arrays, and API interoperability. The basic problem here is that value types fall between primitive types and object types. Value types are clearly more complex than primitive types, and object types are slightly too complicated. Objects are a little bit dangerous to use as value carriers, since object references can be compared for pointer equality, and can be synchronized on. Also, as many Java programmers have observed, there is often a performance cost to using wrapper objects, even on modern JVMs. Even so, wrapper classes are a good starting point for talking about value types. If there were a set of structural rules and restrictions which would prevent value-unsafe operations on value types, wrapper classes would provide a good notation for defining value types. This note attempts to define such rules and restrictions. Let’s Start Coding Now it is time to look at some real code. Here is a definition, written in Java, of a complex number value type. @ValueSafe public final class Complex implements java.io.Serializable {     // immutable component structure:     public final double re, im;     private Complex(double re, double im) {         this.re = re; this.im = im;     }     // interoperability methods:     public String toString() { return "Complex("+re+","+im+")"; }     public List<Double> asList() { return Arrays.asList(re, im); }     public boolean equals(Complex c) {         return re == c.re && im == c.im;     }     public boolean equals(@ValueSafe Object x) {         return x instanceof Complex && equals((Complex) x);     }     public int hashCode() {         return 31*Double.valueOf(re).hashCode()                 + Double.valueOf(im).hashCode();     }     // factory methods:     public static Complex valueOf(double re, double im) {         return new Complex(re, im);     }     public Complex changeRe(double re2) { return valueOf(re2, im); }     public Complex changeIm(double im2) { return valueOf(re, im2); }     public static Complex cast(@ValueSafe Object x) {         return x == null ? ZERO : (Complex) x;     }     // utility methods and constants:     public Complex plus(Complex c)  { return new Complex(re+c.re, im+c.im); }     public Complex minus(Complex c) { return new Complex(re-c.re, im-c.im); }     public double abs() { return Math.sqrt(re*re + im*im); }     public static final Complex PI = valueOf(Math.PI, 0.0);     public static final Complex ZERO = valueOf(0.0, 0.0); } This is not a minimal definition, because it includes some utility methods and other optional parts.  The essential elements are as follows: The class is marked as a value type with an annotation. The class is final, because it does not make sense to create subclasses of value types. The fields of the class are all non-private and final.  (I.e., the type is immutable and structurally transparent.) From the supertype Object, all public non-final methods are overridden. The constructor is private. Beyond these bare essentials, we can observe the following features in this example, which are likely to be typical of all value types: One or more factory methods are responsible for value creation, including a component-wise valueOf method. There are utility methods for complex arithmetic and instance creation, such as plus and changeIm. There are static utility constants, such as PI. The type is serializable, using the default mechanisms. There are methods for converting to and from dynamically typed references, such as asList and cast. The Rules In order to use value types properly, the programmer must avoid value-unsafe operations.  A helpful Java compiler should issue errors (or at least warnings) for code which provably applies value-unsafe operations, and should issue warnings for code which might be correct but does not provably avoid value-unsafe operations.  No such compilers exist today, but to simplify our account here, we will pretend that they do exist. A value-safe type is any class, interface, or type parameter marked with the @ValueSafe annotation, or any subtype of a value-safe type.  If a value-safe class is marked final, it is in fact a value type.  All other value-safe classes must be abstract.  The non-static fields of a value class must be non-public and final, and all its constructors must be private. Under the above rules, a standard interface could be helpful to define value types like Complex.  Here is an example: @ValueSafe public interface ValueType extends java.io.Serializable {     // All methods listed here must get redefined.     // Definitions must be value-safe, which means     // they may depend on component values only.     List<? extends Object> asList();     int hashCode();     boolean equals(@ValueSafe Object c);     String toString(); } //@ValueSafe inherited from supertype: public final class Complex implements ValueType { … The main advantage of such a conventional interface is that (unlike an annotation) it is reified in the runtime type system.  It could appear as an element type or parameter bound, for facilities which are designed to work on value types only.  More broadly, it might assist the JVM to perform dynamic enforcement of the rules for value types. Besides types, the annotation @ValueSafe can mark fields, parameters, local variables, and methods.  (This is redundant when the type is also value-safe, but may be useful when the type is Object or another supertype of a value type.)  Working forward from these annotations, an expression E is defined as value-safe if it satisfies one or more of the following: The type of E is a value-safe type. E names a field, parameter, or local variable whose declaration is marked @ValueSafe. E is a call to a method whose declaration is marked @ValueSafe. E is an assignment to a value-safe variable, field reference, or array reference. E is a cast to a value-safe type from a value-safe expression. E is a conditional expression E0 ? E1 : E2, and both E1 and E2 are value-safe. Assignments to value-safe expressions and initializations of value-safe names must take their values from value-safe expressions. A value-safe expression may not be the subject of a value-unsafe operation.  In particular, it cannot be synchronized on, nor can it be compared with the “==” operator, not even with a null or with another value-safe type. In a program where all of these rules are followed, no value-type value will be subject to a value-unsafe operation.  Thus, the prime axiom of value types will be satisfied, that no two value type will be distinguishable as long as their component values are equal. More Code To illustrate these rules, here are some usage examples for Complex: Complex pi = Complex.valueOf(Math.PI, 0); Complex zero = pi.changeRe(0);  //zero = pi; zero.re = 0; ValueType vtype = pi; @SuppressWarnings("value-unsafe")   Object obj = pi; @ValueSafe Object obj2 = pi; obj2 = new Object();  // ok List<Complex> clist = new ArrayList<Complex>(); clist.add(pi);  // (ok assuming List.add param is @ValueSafe) List<ValueType> vlist = new ArrayList<ValueType>(); vlist.add(pi);  // (ok) List<Object> olist = new ArrayList<Object>(); olist.add(pi);  // warning: "value-unsafe" boolean z = pi.equals(zero); boolean z1 = (pi == zero);  // error: reference comparison on value type boolean z2 = (pi == null);  // error: reference comparison on value type boolean z3 = (pi == obj2);  // error: reference comparison on value type synchronized (pi) { }  // error: synch of value, unpredictable result synchronized (obj2) { }  // unpredictable result Complex qq = pi; qq = null;  // possible NPE; warning: “null-unsafe" qq = (Complex) obj;  // warning: “null-unsafe" qq = Complex.cast(obj);  // OK @SuppressWarnings("null-unsafe")   Complex empty = null;  // possible NPE qq = empty;  // possible NPE (null pollution) The Payoffs It follows from this that either the JVM or the java compiler can replace boxed value-type values with unboxed ones, without affecting normal computations.  Fields and variables of value types can be split into their unboxed components.  Non-static methods on value types can be transformed into static methods which take the components as value parameters. Some common questions arise around this point in any discussion of value types. Why burden the programmer with all these extra rules?  Why not detect programs automagically and perform unboxing transparently?  The answer is that it is easy to break the rules accidently unless they are agreed to by the programmer and enforced.  Automatic unboxing optimizations are tantalizing but (so far) unreachable ideal.  In the current state of the art, it is possible exhibit benchmarks in which automatic unboxing provides the desired effects, but it is not possible to provide a JVM with a performance model that assures the programmer when unboxing will occur.  This is why I’m writing this note, to enlist help from, and provide assurances to, the programmer.  Basically, I’m shooting for a good set of user-supplied “pragmas” to frame the desired optimization. Again, the important thing is that the unboxing must be done reliably, or else programmers will have no reason to work with the extra complexity of the value-safety rules.  There must be a reasonably stable performance model, wherein using a value type has approximately the same performance characteristics as writing the unboxed components as separate Java variables. There are some rough corners to the present scheme.  Since Java fields and array elements are initialized to null, value-type computations which incorporate uninitialized variables can produce null pointer exceptions.  One workaround for this is to require such variables to be null-tested, and the result replaced with a suitable all-zero value of the value type.  That is what the “cast” method does above. Generically typed APIs like List<T> will continue to manipulate boxed values always, at least until we figure out how to do reification of generic type instances.  Use of such APIs will elicit warnings until their type parameters (and/or relevant members) are annotated or typed as value-safe.  Retrofitting List<T> is likely to expose flaws in the present scheme, which we will need to engineer around.  Here are a couple of first approaches: public interface java.util.List<@ValueSafe T> extends Collection<T> { … public interface java.util.List<T extends Object|ValueType> extends Collection<T> { … (The second approach would require disjunctive types, in which value-safety is “contagious” from the constituent types.) With more transformations, the return value types of methods can also be unboxed.  This may require significant bytecode-level transformations, and would work best in the presence of a bytecode representation for multiple value groups, which I have proposed elsewhere under the title “Tuples in the VM”. But for starters, the JVM can apply this transformation under the covers, to internally compiled methods.  This would give a way to express multiple return values and structured return values, which is a significant pain-point for Java programmers, especially those who work with low-level structure types favored by modern vector and graphics processors.  The lack of multiple return values has a strong distorting effect on many Java APIs. Even if the JVM fails to unbox a value, there is still potential benefit to the value type.  Clustered computing systems something have copy operations (serialization or something similar) which apply implicitly to command operands.  When copying JVM objects, it is extremely helpful to know when an object’s identity is important or not.  If an object reference is a copied operand, the system may have to create a proxy handle which points back to the original object, so that side effects are visible.  Proxies must be managed carefully, and this can be expensive.  On the other hand, value types are exactly those types which a JVM can “copy and forget” with no downside. Array types are crucial to bulk data interfaces.  (As data sizes and rates increase, bulk data becomes more important than scalar data, so arrays are definitely accompanying us into the future of computing.)  Value types are very helpful for adding structure to bulk data, so a successful value type mechanism will make it easier for us to express richer forms of bulk data. Unboxing arrays (i.e., arrays containing unboxed values) will provide better cache and memory density, and more direct data movement within clustered or heterogeneous computing systems.  They require the deepest transformations, relative to today’s JVM.  There is an impedance mismatch between value-type arrays and Java’s covariant array typing, so compromises will need to be struck with existing Java semantics.  It is probably worth the effort, since arrays of unboxed value types are inherently more memory-efficient than standard Java arrays, which rely on dependent pointer chains. It may be sufficient to extend the “value-safe” concept to array declarations, and allow low-level transformations to change value-safe array declarations from the standard boxed form into an unboxed tuple-based form.  Such value-safe arrays would not be convertible to Object[] arrays.  Certain connection points, such as Arrays.copyOf and System.arraycopy might need additional input/output combinations, to allow smooth conversion between arrays with boxed and unboxed elements. Alternatively, the correct solution may have to wait until we have enough reification of generic types, and enough operator overloading, to enable an overhaul of Java arrays. Implicit Method Definitions The example of class Complex above may be unattractively complex.  I believe most or all of the elements of the example class are required by the logic of value types. If this is true, a programmer who writes a value type will have to write lots of error-prone boilerplate code.  On the other hand, I think nearly all of the code (except for the domain-specific parts like plus and minus) can be implicitly generated. Java has a rule for implicitly defining a class’s constructor, if no it defines no constructors explicitly.  Likewise, there are rules for providing default access modifiers for interface members.  Because of the highly regular structure of value types, it might be reasonable to perform similar implicit transformations on value types.  Here’s an example of a “highly implicit” definition of a complex number type: public class Complex implements ValueType {  // implicitly final     public double re, im;  // implicitly public final     //implicit methods are defined elementwise from te fields:     //  toString, asList, equals(2), hashCode, valueOf, cast     //optionally, explicit methods (plus, abs, etc.) would go here } In other words, with the right defaults, a simple value type definition can be a one-liner.  The observant reader will have noticed the similarities (and suitable differences) between the explicit methods above and the corresponding methods for List<T>. Another way to abbreviate such a class would be to make an annotation the primary trigger of the functionality, and to add the interface(s) implicitly: public @ValueType class Complex { … // implicitly final, implements ValueType (But to me it seems better to communicate the “magic” via an interface, even if it is rooted in an annotation.) Implicitly Defined Value Types So far we have been working with nominal value types, which is to say that the sequence of typed components is associated with a name and additional methods that convey the intention of the programmer.  A simple ordered pair of floating point numbers can be variously interpreted as (to name a few possibilities) a rectangular or polar complex number or Cartesian point.  The name and the methods convey the intended meaning. But what if we need a truly simple ordered pair of floating point numbers, without any further conceptual baggage?  Perhaps we are writing a method (like “divideAndRemainder”) which naturally returns a pair of numbers instead of a single number.  Wrapping the pair of numbers in a nominal type (like “QuotientAndRemainder”) makes as little sense as wrapping a single return value in a nominal type (like “Quotient”).  What we need here are structural value types commonly known as tuples. For the present discussion, let us assign a conventional, JVM-friendly name to tuples, roughly as follows: public class java.lang.tuple.$DD extends java.lang.tuple.Tuple {      double $1, $2; } Here the component names are fixed and all the required methods are defined implicitly.  The supertype is an abstract class which has suitable shared declarations.  The name itself mentions a JVM-style method parameter descriptor, which may be “cracked” to determine the number and types of the component fields. The odd thing about such a tuple type (and structural types in general) is it must be instantiated lazily, in response to linkage requests from one or more classes that need it.  The JVM and/or its class loaders must be prepared to spin a tuple type on demand, given a simple name reference, $xyz, where the xyz is cracked into a series of component types.  (Specifics of naming and name mangling need some tasteful engineering.) Tuples also seem to demand, even more than nominal types, some support from the language.  (This is probably because notations for non-nominal types work best as combinations of punctuation and type names, rather than named constructors like Function3 or Tuple2.)  At a minimum, languages with tuples usually (I think) have some sort of simple bracket notation for creating tuples, and a corresponding pattern-matching syntax (or “destructuring bind”) for taking tuples apart, at least when they are parameter lists.  Designing such a syntax is no simple thing, because it ought to play well with nominal value types, and also with pre-existing Java features, such as method parameter lists, implicit conversions, generic types, and reflection.  That is a task for another day. Other Use Cases Besides complex numbers and simple tuples there are many use cases for value types.  Many tuple-like types have natural value-type representations. These include rational numbers, point locations and pixel colors, and various kinds of dates and addresses. Other types have a variable-length ‘tail’ of internal values. The most common example of this is String, which is (mathematically) a sequence of UTF-16 character values. Similarly, bit vectors, multiple-precision numbers, and polynomials are composed of sequences of values. Such types include, in their representation, a reference to a variable-sized data structure (often an array) which (somehow) represents the sequence of values. The value type may also include ’header’ information. Variable-sized values often have a length distribution which favors short lengths. In that case, the design of the value type can make the first few values in the sequence be direct ’header’ fields of the value type. In the common case where the header is enough to represent the whole value, the tail can be a shared null value, or even just a null reference. Note that the tail need not be an immutable object, as long as the header type encapsulates it well enough. This is the case with String, where the tail is a mutable (but never mutated) character array. Field types and their order must be a globally visible part of the API.  The structure of the value type must be transparent enough to have a globally consistent unboxed representation, so that all callers and callees agree about the type and order of components  that appear as parameters, return types, and array elements.  This is a trade-off between efficiency and encapsulation, which is forced on us when we remove an indirection enjoyed by boxed representations.  A JVM-only transformation would not care about such visibility, but a bytecode transformation would need to take care that (say) the components of complex numbers would not get swapped after a redefinition of Complex and a partial recompile.  Perhaps constant pool references to value types need to declare the field order as assumed by each API user. This brings up the delicate status of private fields in a value type.  It must always be possible to load, store, and copy value types as coordinated groups, and the JVM performs those movements by moving individual scalar values between locals and stack.  If a component field is not public, what is to prevent hostile code from plucking it out of the tuple using a rogue aload or astore instruction?  Nothing but the verifier, so we may need to give it more smarts, so that it treats value types as inseparable groups of stack slots or locals (something like long or double). My initial thought was to make the fields always public, which would make the security problem moot.  But public is not always the right answer; consider the case of String, where the underlying mutable character array must be encapsulated to prevent security holes.  I believe we can win back both sides of the tradeoff, by training the verifier never to split up the components in an unboxed value.  Just as the verifier encapsulates the two halves of a 64-bit primitive, it can encapsulate the the header and body of an unboxed String, so that no code other than that of class String itself can take apart the values. Similar to String, we could build an efficient multi-precision decimal type along these lines: public final class DecimalValue extends ValueType {     protected final long header;     protected private final BigInteger digits;     public DecimalValue valueOf(int value, int scale) {         assert(scale >= 0);         return new DecimalValue(((long)value << 32) + scale, null);     }     public DecimalValue valueOf(long value, int scale) {         if (value == (int) value)             return valueOf((int)value, scale);         return new DecimalValue(-scale, new BigInteger(value));     } } Values of this type would be passed between methods as two machine words. Small values (those with a significand which fits into 32 bits) would be represented without any heap data at all, unless the DecimalValue itself were boxed. (Note the tension between encapsulation and unboxing in this case.  It would be better if the header and digits fields were private, but depending on where the unboxing information must “leak”, it is probably safer to make a public revelation of the internal structure.) Note that, although an array of Complex can be faked with a double-length array of double, there is no easy way to fake an array of unboxed DecimalValues.  (Either an array of boxed values or a transposed pair of homogeneous arrays would be reasonable fallbacks, in a current JVM.)  Getting the full benefit of unboxing and arrays will require some new JVM magic. Although the JVM emphasizes portability, system dependent code will benefit from using machine-level types larger than 64 bits.  For example, the back end of a linear algebra package might benefit from value types like Float4 which map to stock vector types.  This is probably only worthwhile if the unboxing arrays can be packed with such values. More Daydreams A more finely-divided design for dynamic enforcement of value safety could feature separate marker interfaces for each invariant.  An empty marker interface Unsynchronizable could cause suitable exceptions for monitor instructions on objects in marked classes.  More radically, a Interchangeable marker interface could cause JVM primitives that are sensitive to object identity to raise exceptions; the strangest result would be that the acmp instruction would have to be specified as raising an exception. @ValueSafe public interface ValueType extends java.io.Serializable,         Unsynchronizable, Interchangeable { … public class Complex implements ValueType {     // inherits Serializable, Unsynchronizable, Interchangeable, @ValueSafe     … It seems possible that Integer and the other wrapper types could be retro-fitted as value-safe types.  This is a major change, since wrapper objects would be unsynchronizable and their references interchangeable.  It is likely that code which violates value-safety for wrapper types exists but is uncommon.  It is less plausible to retro-fit String, since the prominent operation String.intern is often used with value-unsafe code. We should also reconsider the distinction between boxed and unboxed values in code.  The design presented above obscures that distinction.  As another thought experiment, we could imagine making a first class distinction in the type system between boxed and unboxed representations.  Since only primitive types are named with a lower-case initial letter, we could define that the capitalized version of a value type name always refers to the boxed representation, while the initial lower-case variant always refers to boxed.  For example: complex pi = complex.valueOf(Math.PI, 0); Complex boxPi = pi;  // convert to boxed myList.add(boxPi); complex z = myList.get(0);  // unbox Such a convention could perhaps absorb the current difference between int and Integer, double and Double. It might also allow the programmer to express a helpful distinction among array types. As said above, array types are crucial to bulk data interfaces, but are limited in the JVM.  Extending arrays beyond the present limitations is worth thinking about; for example, the Maxine JVM implementation has a hybrid object/array type.  Something like this which can also accommodate value type components seems worthwhile.  On the other hand, does it make sense for value types to contain short arrays?  And why should random-access arrays be the end of our design process, when bulk data is often sequentially accessed, and it might make sense to have heterogeneous streams of data as the natural “jumbo” data structure.  These considerations must wait for another day and another note. More Work It seems to me that a good sequence for introducing such value types would be as follows: Add the value-safety restrictions to an experimental version of javac. Code some sample applications with value types, including Complex and DecimalValue. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. A staggered roll-out like this would decouple language changes from bytecode changes, which is always a convenient thing. A similar investigation should be applied (concurrently) to array types.  In this case, it seems to me that the starting point is in the JVM: Add an experimental unboxing array data structure to a production JVM, perhaps along the lines of Maxine hybrids.  No bytecode or language support is required at first; everything can be done with encapsulated unsafe operations and/or method handles. Create an experimental JVM which internally unboxes value types but does not require new bytecodes to do so.  Ensure the feasibility of the performance model for the sample applications. Add tuple-like bytecodes (with or without generic type reification) to a major revision of the JVM, and teach the Java compiler to switch in the new bytecodes without code changes. That’s enough musing me for now.  Back to work!

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• ASP.Net How to enforce the HTTP get URL format?

  - by Hamish Grubijan

  [Sorry about a messy question. I believe I am targeting .Net 2.0 (for now)] Hi, I am an ASP.NET noob. For starters I am building a page that parses a URL string and populates a table in a database. I want that string to be strictly of the form: http://<server>:<port>/PageName.aspx?A=1&B=2&C=3&D=4&E=5 The order of the arguments do not matter, I just do not want any of them missing, or any extras. Here is what I tried (yes, it is ugly; I just want to get it to work first): #if (DEBUG) // Maps parameter names to their human readable names. // Used for error checking. private static Dictionary<string, string> paramNameToDisplayName = new Dictionary<string, string> { { A, "a"}, { B, "b"}, { C, "c"}, { D, "d"}, { E, "e"}, { F, "f"}, }; [Conditional("DEBUG")] private void validateRequestParameters(HttpRequest request) { bool endResponse = false; // Use foreach var foreach (string expectedParameterName in paramNameToDisplayName.Keys) { if (request[expectedParameterName] == null) { Response.Write(String.Format("No parameter \"{0}\", aka {1} was passed to the configuration generator. Check your URL string / cookie.", expectedParameterName, paramNameToDisplayName[expectedParameterName])); endResponse = true; } } // Use foreach var foreach (string actualParameterName in request.Params) { if (!paramNameToDisplayName.ContainsKey(actualParameterName)) { Response.Write(String.Format("The parameter \"{0}\", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.", actualParameterName)); endResponse = true; } } if (endResponse) { Response.End(); } } #endif and it works ok, except that it complains about all sorts of other stuff: http://localhost:1796/AddStatusUpdate.aspx?X=0 No parameter "A", aka a was passed to the configuration generator. Check your URL string / cookie.No parameter "B", aka b was passed to the configuration generator. Check your URL string / cookie.No parameter "C", aka c was passed to the configuration generator. Check your URL string / cookie.No parameter "D", aka d was passed to the configuration generator. Check your URL string / cookie.No parameter "E", aka e was passed to the configuration generator. Check your URL string / cookie.No parameter "F", aka f was passed to the configuration generator. Check your URL string / cookie.The parameter "X", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ASP.NET_SessionId", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ALL_HTTP", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "ALL_RAW", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "APPL_MD_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "APPL_PHYSICAL_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_TYPE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "AUTH_PASSWORD", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "LOGON_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_USER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_COOKIE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_FLAGS", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_KEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SECRETKEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERIALNUMBER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERVER_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SERVER_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CERT_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CONTENT_LENGTH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "CONTENT_TYPE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "GATEWAY_INTERFACE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_KEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SECRETKEYSIZE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SERVER_ISSUER", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTPS_SERVER_SUBJECT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "INSTANCE_ID", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "INSTANCE_META_PATH", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "LOCAL_ADDR", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "PATH_INFO", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "PATH_TRANSLATED", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "QUERY_STRING", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_ADDR", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_HOST", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REMOTE_PORT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "REQUEST_METHOD", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SCRIPT_NAME", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_NAME", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PORT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PORT_SECURE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_PROTOCOL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "SERVER_SOFTWARE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "URL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_CACHE_CONTROL", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_CONNECTION", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_CHARSET", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_ENCODING", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_ACCEPT_LANGUAGE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_COOKIE", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_HOST", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.The parameter "HTTP_USER_AGENT", was passed to the configuration generator, but it was not expected. Check your URL string / cookie.Thread was being aborted. Is there some way for me to separate the implicit and the explicit parameters, or is it not doable? Should I even bother? Perhaps the philosophy of get is to just throw away that what is not needed. Thanks!

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• CSS Menus having cross browser problems

  - by George

  I am trying to solve a problem with a CSS menu where the menu does not display properly in IE 6 I see that the HTML has some conditional code to make it work with different browsers but I do not understand it well enough. Can someone suggest a fix so the selected tab in order displayed without the grey breaK? Thanks! #pad { height: 140px; } .dropline { position: relative; padding-bottom: 0px; list-style-type: none; margin: 0px 0px 0px 5px; padding-left: 0px; width: 860px; padding-right: 0px; background: url(../images/menus/ulback.gif) repeat-x; height: 40px; top: 0px; list-style-image: none; padding-top: 0px; left: 5px; } .dropline TABLE { margin: -3px -10px; width: 25px; border-collapse: collapse; height: 17px; } .dropline LI { margin-bottom: 0px; float: left; } .dropline LI A { padding-bottom: 0px; line-height: 40px; padding-left: 0px; padding-right: 19px; display: block; font-family: tahoma, sans-serif; float: left; height: 40px; color: #fff; font-size: 12px; text-decoration: none; padding-top: 0px; } .dropline A { text-align: right; padding-bottom: 0px; line-height: 40px; padding-left: 0px; padding-right: 19px; font-family: tahoma, sans-serif; float: right; height: 40px; color: #fff; font-size: 12px; text-decoration: none; padding-top: 0px; } .dropline A:hover { color: yellow; } .welcomeuser { text-align: right; padding-bottom: 0px; line-height: 40px; padding-left: 20px; padding-right: 0px; font-family: tahoma, sans-serif; float: right; height: 40px; color: #fff; clear: inherit; font-size: 12px; text-decoration: none; padding-top: 0px; } .dropline LI A B { padding-bottom: 0px; padding-left: 20px; padding-right: 0px; display: block; float: left; height: 40px; cursor: pointer; padding-top: 0px; } .dropline UL { z-index: 10; border-bottom: #fff 1px solid; position: absolute; padding-bottom: 0px; list-style-type: none; margin: 0px; padding-left: 0px; width: 860px; padding-right: 0px; background: #f8f8f8; height: 25px; border-top: #ff9933 3px solid; top: 40px; list-style-image: none; padding-top: 0px; left: -9999px; } .dropline UL LI { line-height: 25px; height: 25px; } .dropline UL.right LI { float: right; } .dropline UL LI A { padding-bottom: 0px; line-height: 25px; padding-left: 10px; padding-right: 10px; height: 25px; color: #000; font-size: 11px; font-weight: bold; border-right: #e60 1px solid; padding-top: 0px; } .dropline UL LI A:hover { line-height: 25px; background: none transparent scroll repeat 0% 0%; height: 25px; color: #c60; } .dropline UL.right LI A { border-left: #e60 1px solid; border-right: 0px; } .dropline UL LI A.last { border-bottom: 0px; border-left: 0px; border-top: 0px; border-right: 0px; } .dropline :hover UL { left: 0px; } .dropline LI.current UL { z-index: 1; left: 0px; } .dropline LI.current A { line-height: 36px; background: url(../images/menus/tab_a.gif) no-repeat right top; height: 44px; } .dropline LI.current A B { line-height: 36px; background: url(../images/menus/tab_b.gif) no-repeat left top; } .dropline LI.current UL LI A { padding-bottom: 0px; line-height: 25px; padding-left: 10px; padding-right: 10px; background: none transparent scroll repeat 0% 0%; height: 25px; color: #000; padding-top: 0px; } .dropline LI.current UL LI.current_sub A { color: #c60; } .dropline LI.current UL LI A:hover { color: #c60; } <div id="top_nav"> <asp:ContentPlaceHolder ID="phTopNav" runat="server"> <!-- MENU --> <ul id="dropline" class="dropline" runat="server" style="left: -6px; top: -2px; width:1000px;" clientidmode="Static"> <li runat="server" id="Home"> <a runat="server" id="lnkHome" href="../Default.aspx" title="Go to the Home page"><b>Home</b> <!--[if gte IE 7]><!--></a> <!--<![endif]--> <!--[if lte IE 6]> <table> <tr> <td> <![endif]--><!--[if lte IE 6]> </td> </tr> </table> </a><![endif]--> </li> <li runat="server" id="ApplyNow"> <a runat="server" id="lnkEditOrder" href="../OrderChinaVisa.aspx" title="Use our Price Calculator and simultaneously begin the China Visa application process!"><b>Apply Now!</b> <!--[if gte IE 7]><!--></a> <!--<![endif]--> <!--[if lte IE 6]> <table> <tr> <td> <![endif]--><!--[if lte IE 6]> </td> </tr> </table> </a><![endif]--> </li> <li runat="server" id="CheckStatus"> <a id="lnkCheckStatus" runat="server" href="../Check_Status.aspx" title="Check on the status of a placed order"><b>Check Status</b><!--[if gte IE 7]><!--></a><!--<![endif]--> <!--[if lte IE 6]> <table> <tr> <td> <![endif]--><!--[if lte IE 6]> </td> </tr> </table> </a><![endif]--></li> <li runat="server" id="Affiliate"> <a id="lnkAffiliate" runat="server" href="../Secure/VisaActivity.aspx" title=""><b>Affiliate</b><!--[if gte IE 7]><!--></a><!--<![endif]--> <!--[if lte IE 6]> <table> <tr> <td> <![endif]--><!--[if lte IE 6]> </td> </tr> </table> </a><![endif]--></li> </ul> </asp:ContentPlaceHolder> </div>

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• How to Make a Game like Space Invaders - Ray Wenderlich (why do my space invaders scroll off screen)

  - by Erv Noel

  I'm following this tutorial(http://www.raywenderlich.com/51068/how-to-make-a-game-like-space-invaders-with-sprite-kit-tutorial-part-1) and I've run into a problem right after the part where I add [self determineInvaderMovementDirection]; to my GameScene.m file (specifically to my moveInvadersForUpdate method) The tutorial states that the space invaders should be moving accordingly after adding this piece of code but when I run they move to the left and they do not come back. I'm not sure what I am doing wrong as I have followed this tutorial very carefully. Any help or clarification would be greatly appreciated. Thanks in advance ! Here is the full GameScene.m #import "GameScene.h" #import <CoreMotion/CoreMotion.h> #pragma mark - Custom Type Definitions /* The type definition and constant definitions 1,2,3 take care of the following tasks: 1.Define the possible types of invader enemies. This can be used in switch statements later when things like displaying different sprites images for each enemy type. The typedef makes InvaderType a formal Obj-C type that is type checked for method arguments and variables.This is so that the wrong method argument is not used or assigned to the wrong variable. 2. Define the size of the invaders and that they'll be laid out in a grid of rows and columns on the screen. 3. Define a name that will be used to identify invaders when searching for them. */ //1 typedef enum InvaderType { InvaderTypeA, InvaderTypeB, InvaderTypeC } InvaderType; /* Invaders move in a fixed pattern: right, right, down, left, down, right right. InvaderMovementDirection tracks the invaders' progress through this pattern */ typedef enum InvaderMovementDirection { InvaderMovementDirectionRight, InvaderMovementDirectionLeft, InvaderMovementDirectionDownThenRight, InvaderMovementDirectionDownThenLeft, InvaderMovementDirectionNone } InvaderMovementDirection; //2 #define kInvaderSize CGSizeMake(24,16) #define kInvaderGridSpacing CGSizeMake(12,12) #define kInvaderRowCount 6 #define kInvaderColCount 6 //3 #define kInvaderName @"invader" #define kShipSize CGSizeMake(30, 16) //stores the size of the ship #define kShipName @"ship" // stores the name of the ship stored on the sprite node #define kScoreHudName @"scoreHud" #define kHealthHudName @"healthHud" /* this class extension allows you to add “private” properties to GameScene class, without revealing the properties to other classes or code. You still get the benefit of using Objective-C properties, but your GameScene state is stored internally and can’t be modified by other external classes. As well, it doesn’t clutter the namespace of datatypes that your other classes see. This class extension is used in the method didMoveToView */ #pragma mark - Private GameScene Properties @interface GameScene () @property BOOL contentCreated; @property InvaderMovementDirection invaderMovementDirection; @property NSTimeInterval timeOfLastMove; @property NSTimeInterval timePerMove; @end @implementation GameScene #pragma mark Object Lifecycle Management #pragma mark - Scene Setup and Content Creation /*This method simply invokes createContent using the BOOL property contentCreated to make sure you don’t create your scene’s content more than once. This property is defined in an Objective-C Class Extension found near the top of the file()*/ - (void)didMoveToView:(SKView *)view { if (!self.contentCreated) { [self createContent]; self.contentCreated = YES; } } - (void)createContent { //1 - Invaders begin by moving to the right self.invaderMovementDirection = InvaderMovementDirectionRight; //2 - Invaders take 1 sec for each move. Each step left, right or down // takes 1 second. self.timePerMove = 1.0; //3 - Invaders haven't moved yet, so set the time to zero self.timeOfLastMove = 0.0; [self setupInvaders]; [self setupShip]; [self setupHud]; } /* Creates an invade sprite of a given type 1. Use the invadeType parameterr to determine color of the invader 2. Call spriteNodeWithColor:size: of SKSpriteNode to alloc and init a sprite that renders as a rect of the given color invaderColor with size kInvaderSize */ -(SKNode*)makeInvaderOfType:(InvaderType)invaderType { //1 SKColor* invaderColor; switch (invaderType) { case InvaderTypeA: invaderColor = [SKColor redColor]; break; case InvaderTypeB: invaderColor = [SKColor greenColor]; break; case InvaderTypeC: invaderColor = [SKColor blueColor]; break; } //2 SKSpriteNode* invader = [SKSpriteNode spriteNodeWithColor:invaderColor size:kInvaderSize]; invader.name = kInvaderName; return invader; } -(void)setupInvaders { //1 - loop over the rows CGPoint baseOrigin = CGPointMake(kInvaderSize.width / 2, 180); for (NSUInteger row = 0; row < kInvaderRowCount; ++row) { //2 - Choose a single InvaderType for all invaders // in this row based on the row number InvaderType invaderType; if (row % 3 == 0) invaderType = InvaderTypeA; else if (row % 3 == 1) invaderType = InvaderTypeB; else invaderType = InvaderTypeC; //3 - Does some math to figure out where the first invader // in the row should be positioned CGPoint invaderPosition = CGPointMake(baseOrigin.x, row * (kInvaderGridSpacing.height + kInvaderSize.height) + baseOrigin.y); //4 - Loop over the columns for (NSUInteger col = 0; col < kInvaderColCount; ++col) { //5 - Create an invader for the current row and column and add it // to the scene SKNode* invader = [self makeInvaderOfType:invaderType]; invader.position = invaderPosition; [self addChild:invader]; //6 - update the invaderPosition so that it's correct for the //next invader invaderPosition.x += kInvaderSize.width + kInvaderGridSpacing.width; } } } -(void)setupShip { //1 - creates ship using makeShip. makeShip can easily be used later // to create another ship (ex. to set up more lives) SKNode* ship = [self makeShip]; //2 - Places the ship on the screen. In SpriteKit the origin is at the lower //left corner of the screen. The anchorPoint is based on a unit square with (0, 0) at the lower left of the sprite's area and (1, 1) at its top right. Since SKSpriteNode has a default anchorPoint of (0.5, 0.5), i.e., its center, the ship's position is the position of its center. Positioning the ship at kShipSize.height/2.0f means that half of the ship's height will protrude below its position and half above. If you check the math, you'll see that the ship's bottom aligns exactly with the bottom of the scene. ship.position = CGPointMake(self.size.width / 2.0f, kShipSize.height/2.0f); [self addChild:ship]; } -(SKNode*)makeShip { SKNode* ship = [SKSpriteNode spriteNodeWithColor:[SKColor greenColor] size:kShipSize]; ship.name = kShipName; return ship; } -(void)setupHud { //Sets the score label font to Courier SKLabelNode* scoreLabel = [SKLabelNode labelNodeWithFontNamed:@"Courier"]; //1 - Give the score label a name so it becomes easy to find later when // the score needs to be updated. scoreLabel.name = kScoreHudName; scoreLabel.fontSize = 15; //2 - Color the score label green scoreLabel.fontColor = [SKColor greenColor]; scoreLabel.text = [NSString stringWithFormat:@"Score: %04u", 0]; //3 - Positions the score label near the top left corner of the screen scoreLabel.position = CGPointMake(20 + scoreLabel.frame.size.width/2, self.size.height - (20 + scoreLabel.frame.size.height/2)); [self addChild:scoreLabel]; //Applies the font of the health label SKLabelNode* healthLabel = [SKLabelNode labelNodeWithFontNamed:@"Courier"]; //4 - Give the health label a name so it can be referenced later when it needs // to be updated to display the health healthLabel.name = kHealthHudName; healthLabel.fontSize = 15; //5 - Colors the health label red healthLabel.fontColor = [SKColor redColor]; healthLabel.text = [NSString stringWithFormat:@"Health: %.1f%%", 100.0f]; //6 - Positions the health Label on the upper right hand side of the screen healthLabel.position = CGPointMake(self.size.width - healthLabel.frame.size.width/2 - 20, self.size.height - (20 + healthLabel.frame.size.height/2)); [self addChild:healthLabel]; } #pragma mark - Scene Update - (void)update:(NSTimeInterval)currentTime { //Makes the invaders move [self moveInvadersForUpdate:currentTime]; } #pragma mark - Scene Update Helpers //This method will get invoked by update -(void)moveInvadersForUpdate:(NSTimeInterval)currentTime { //1 - if it's not yet time to move, exit the method. moveInvadersForUpdate: // is invoked 60 times per second, but you don't want the invaders to move // that often since the movement would be too fast to see if (currentTime - self.timeOfLastMove < self.timePerMove) return; //2 - Recall that the scene holds all the invaders as child nodes; which were // added to the scene using addChild: in setupInvaders identifying each invader // by its name property. Invoking enumerateChildNodesWithName:usingBlock only loops over the invaders because they're named kInvaderType; which makes the loop skip the ship and the HUD. The guts og the block moves the invaders 10 pixels either right, left or down depending on the value of invaderMovementDirection [self enumerateChildNodesWithName:kInvaderName usingBlock:^(SKNode *node, BOOL *stop) { switch (self.invaderMovementDirection) { case InvaderMovementDirectionRight: node.position = CGPointMake(node.position.x - 10, node.position.y); break; case InvaderMovementDirectionLeft: node.position = CGPointMake(node.position.x - 10, node.position.y); break; case InvaderMovementDirectionDownThenLeft: case InvaderMovementDirectionDownThenRight: node.position = CGPointMake(node.position.x, node.position.y - 10); break; InvaderMovementDirectionNone: default: break; } }]; //3 - Record that you just moved the invaders, so that the next time this method is invoked (1/60th of a second from when it starts), the invaders won't move again until the set time period of one second has elapsed. self.timeOfLastMove = currentTime; //Makes it so that the invader movement direction changes only when the invaders are actually moving. Invaders only move when the check on self.timeOfLastMove passes (when conditional expression is true) [self determineInvaderMovementDirection]; } #pragma mark - Invader Movement Helpers -(void)determineInvaderMovementDirection { //1 - Since local vars accessed by block are default const(means they cannot be changed), this snippet of code qualifies proposedMovementDirection with __block so that you can modify it in //2 __block InvaderMovementDirection proposedMovementDirection = self.invaderMovementDirection; //2 - Loops over the invaders in the scene and refers to the block with the invader as an argument [self enumerateChildNodesWithName:kInvaderName usingBlock:^(SKNode *node, BOOL *stop) { switch (self.invaderMovementDirection) { case InvaderMovementDirectionRight: //3 - If the invader's right edge is within 1pt of the right edge of the scene, it's about to move offscreen. Sets proposedMovementDirection so that the invaders move down then left. You compare the invader's frame(the frame that contains its content in the scene's coordinate system) with the scene width. Since the scene has an anchorPoint of (0,0) by default and is scaled to fill it's parent view, this comparison ensures you're testing against the view's edges. if (CGRectGetMaxX(node.frame) >= node.scene.size.width - 1.0f) { proposedMovementDirection = InvaderMovementDirectionDownThenLeft; *stop = YES; } break; case InvaderMovementDirectionLeft: //4 - If the invader's left edge is within 1 pt of the left edge of the scene, it's about to move offscreen. Sets the proposedMovementDirection so invaders move down then right if (CGRectGetMinX(node.frame) <= 1.0f) { proposedMovementDirection = InvaderMovementDirectionDownThenRight; *stop = YES; } break; case InvaderMovementDirectionDownThenLeft: //5 - If invaders are moving down then left, they already moved down at this point, so they should now move left. proposedMovementDirection = InvaderMovementDirectionLeft; *stop = YES; break; case InvaderMovementDirectionDownThenRight: //6 - if the invaders are moving down then right, they already moved down so they should now move right. proposedMovementDirection = InvaderMovementDirectionRight; *stop = YES; break; default: break; } }]; //7 - if the proposed invader movement direction is different than the current invader movement direction, update the current direction to the proposed direction if (proposedMovementDirection != self.invaderMovementDirection) { self.invaderMovementDirection = proposedMovementDirection; } } #pragma mark - Bullet Helpers #pragma mark - User Tap Helpers #pragma mark - HUD Helpers #pragma mark - Physics Contact Helpers #pragma mark - Game End Helpers @end

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• Is there a better loop I could write to reduce database queries?

  - by dmanexe

  Below is some code I've written that is effective, but makes too many database queries. Is there a way I could optimize and reduce the number of queries but have conditional statements still be as effective as below? I pasted the code repeated a few times just for good measure. echo "<h3>Pool Packages</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Pool Packages") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Pool Packages") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Water Features</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Water Features") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Water Features") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Waterfall Rock Work</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE) { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Waterfall Rock Work") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Sheer Descents</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Sheer Descents") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Sheer Descents") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Booster Pump</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Booster Pump") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Booster Pump") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Pool Concrete Decking</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Pool Concrete Decking") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Pool Concrete Decking") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Solar Heating</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Solar Heating") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Solar Heating") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { } endforeach; echo "</ul>"; echo "<h3>Raised Bond Beam</h3>"; echo "<ul>"; foreach ($items as $item): $this->db->where('id', $item['id']); $query = $this->db->get('items')->row(); if ($item['quantity'] > 1 && $item['quantity'] == TRUE && $query->category == "Raised Bond Beam") { $newprice = $item['quantity'] * $query->price; $totals[] = $newprice; } else { $newprice = $query->price; $totals[] = $newprice; } if ($query->category == "Raised Bond Beam") { echo "<li>" . $query->name . " (QTY: " . $item['quantity'] . " x = " . str_ireplace(" ", "", money_format('%(#10n', $newprice)) . ")</li>"; } else { echo "<li>None</li>"; } endforeach; echo "</ul>"; It goes on beyond this to several more categories, but I don't know how to handle looping through this best. Thanks!

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