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• SOA Suite 11g Native Format Builder Complex Format Example

  - by bob.webster

  This rather long posting details the steps required to process a grouping of fixed length records using Format Builder.   If it’s 10 pm and you’re feeling beat you might want to leave this until tomorrow.  But if it’s 10 pm and you need to get a Format Builder Complex template done, read on… The goal is to process individual orders from a file using the 11g File Adapter and Format Builder Sample Data =========== 001Square Widget            0245.98 102Triagular Widget         1120.00 403Circular Widget           0099.45 ORD8898302/01/2011 301Hexagon Widget         1150.98 ORD6735502/01/2011 The records are fixed length records representing a number of logical Order records. Each order record consists of a number of item records starting with a 3 digit number, followed by a single Summary Record which starts with the constant ORD. How can this file be processed so that the first poll returns the first order? 001Square Widget            0245.98 102Triagular Widget         1120.00 403Circular Widget           0099.45 ORD8898302/01/2011 And the second poll returns the second order? 301Hexagon Widget           1150.98 ORD6735502/01/2011 Note: if you need more than one order per poll, that’s also possible, see the “Multiple Messages” field in the “File Adapter Step 6 of 9” snapshot further down.   To follow along with this example you will need - Studio Edition Version 11.1.1.4.0    with the   - SOA Extension for JDeveloper 11.1.1.4.0 installed Both can be downloaded from here:  http://www.oracle.com/technetwork/middleware/soasuite/downloads/index.html You will not need a running WebLogic Server domain to complete the steps and Format Builder tests in this article.     Start with a SOA Composite containing a File Adapter The Format Builder is part of the File Adapter so start by creating a new SOA Project and Composite. Here is a quick summary for those not familiar with these steps - Start JDeveloper - From the Main Menu choose File->New - In the New Gallery window that opens Expand the “General” category and Select the Applications node.   Then choose SOA Application from the Items section on the right.  Finally press the OK button. - In Step 1 of the “Create SOA Application wizard” that appears enter an Application Name and an Directory of your     choice,   then press the Next button. - In Step 2 of the “Create SOA Application wizard”, press the Next button leaving all entries as defaulted. - In Step 3 of the “Create SOA Application wizard”, Enter a composite name of your choice and Press the Finish   Button These steps result in a new Application and SOA Project. The SOA Project contains a composite.xml file which is opened and shown below. For our example we have not defined a Mediator or a BPEL process to minimize the steps, but one or the other would eventually be needed to use the File Adapter we are about to create. Drag and drop the File Adapter icon from the Component Pallette onto either the LEFT side of the diagram under “Exposed Services” or the right side under “External References”.  (See the Green Circle in the image below).  Placing the adapter on the left side would indicate the file being processed is inbound to the composite, if the adapter is placed on the right side then the data is outbound to a file.     Note that the same Format Builder definition can be used in both directions.  For example we could use the format with a File Adapter on the left side of the composite to parse fixed data into XML, modify the data in our Composite or BPEL process and then use the same Format Builder definition with a File adapter on the right side of the composite to write the data back out in the same fixed data format When the File Adapter is dropped on the Composite the File Adapter Wizard Appears. Skip Past the first page, Step 1 of 9 by pressing the Next button. In Step 2 enter a service name of your choice as shown below, then press Next   When the Native Format Builder appears, skip the welcome page by pressing next. Also press the Next button to accept the settings on Step 3 of 9 On Step 4, select Read File and press the Next button as shown below.   On Step 5 enter a directory that will contain a file with the input data, then  Press the Next button as shown below. In step 6, enter *.txt or another file format to select input files from the input directory mentioned in step 5. ALSO check the “Files contain Multiple Messages” checkbox and set the “Publish Messages in Batches of” field to 1.  The value can be set higher to increase the number of logical order group records returned on each poll of the file adapter.  In other words, it determines the number of Orders that will be sent to each instance of a Mediator or Composite processing using the File Adapter.   Skip Step 7 by pressing the Next button In Step 8 press the Gear Icon on the right side to load the Native Format Builder.       Native Format Builder  appears Before diving into the format, here is an overview of the process. Approach - Bottom up Assuming an Order is a grouping of item records and a summary record…. - Define a separate  Complex Type for each Record Type found in the group.    (One for itemRecord and one for summaryRecord) - Define a Complex Type to contain the Group of Record types defined above   (LogicalOrderRecord) - Define a top level element to represent an order.  (order)   The order element will be of type LogicalOrderRecord   Defining the Format In Step 1 select   “Create new”  and  “Complex Type” and “Next”   In Step two browse to and select a file containing the test data shown at the start of this article. A link is provided at the end of this article to download a file containing the test data. Press the Next button     In Step 3 Complex types must be define for each type of input record. Select the Root-Element and Click on the Add Complex Type icon This creates a new empty complex type definition shown below. The fastest way to create the definition is to highlight the first line of the Sample File data and drag the line onto the  <new_complex_type> Format Builder introspects the data and provides a grid to define additional fields. Change the “Complex Type Name” to  “itemRecord” Then click on the ruler to indicate the position of fixed columns.  Drag the red triangle icons to the exact columns if necessary. Double click on an existing red triangle to remove an unwanted entry. In the case below fields are define in columns 0-3, 4-28, 29-eol When the field definitions are correct, press the “Generate Fields” button. Field entries named C1, C2 and C3 will be created as shown below. Click on the field names and rename them from C1->itemNum, C2->itemDesc and C3->itemCost  When all the fields are correctly defined press OK to save the complex type.        Next, the process is repeated to define a Complex Type for the SummaryRecord. Select the Root-Element in the schema tree and press the new complex type icon Then highlight and drag the Summary Record from the sample data onto the <new_complex_type>   Change the complex type name to “summaryRecord” Mark the fixed fields for Order Number and Order Date. Press the Generate Fields button and rename C1 and C2 to itemNum and orderDate respectively.   The last complex type to be defined is a type to hold the group of items and the summary record. Select the Root-Element in the schema tree and click the new complex type icon Select the “<new_complex_type>” entry and click the pencil icon   On the Complex Type Details page change the name and type of each input field. Change line 1 to be named item and set the Type  to “itemRecord” Change line 2 to be named summary and set the Type to “summaryRecord” We also need to indicate that itemRecords repeat in the input file. Click the pencil icon at the right side of the item line. On the Edit Details page change the “Max Occurs” entry from 1 to UNBOUNDED. We also need to indicate how to identify an itemRecord.  Since each item record has “.” in column 32 we can use this fact to differentiate an item record from a summary record. Change the “Look Ahead” field to value 32 and enter a period in the “Look For” field Press the OK button to save entry.     Finally, its time to create a top level element to represent an order. Select the “Root-Element” in the schema tree and press the New element icon Click on the <new_element> and press the pencil icon.   Set the Element Name to “order” and change the Data Type to “logicalOrderRecord” Press the OK button to save the element definition.   The final definition should match the screenshot below. Press the Next Button to view the definition source.     Press the Test Button to test the definition   Press the Green Triangle Icon to run the test.   And we are presented with an unwelcome error. The error states that the processor ran out of data while working through the definition. The processor was unable to differentiate between itemRecords and summaryRecords and therefore treated the entire file as a list of itemRecords.  At end of file, the “summary” portion of the logicalOrderRecord remained unprocessed but mandatory.   This root cause of this error is the loss of our “lookAhead” definition used to identify itemRecords. This appears to be a bug in the  Native Format Builder 11.1.1.4.0 Luckily, a simple workaround exists. Press the Cancel button and return to the “Step 4 of 4” Window. Manually add    nxsd:lookAhead="32" nxsd:lookFor="."   attributes after the maxOccurs attribute of the item element. as shown in the highlighted text below.   When the lookAhead and lookFor attributes have been added Press the Test button and on the Test page press the Green Triangle. The test is now successful, the first order in the file is returned by the File Adapter.     Below is a complete listing of the Result XML from the right column of the screen above   Try running it The downloaded input test file and completed schema file can be used for testing without following all the Native Format Builder steps in this example. Use the following link to download a file containing the sample data. Download Sample Input Data This is the best approach rather than cutting and pasting the input data at the top of the article.  Since the data is fixed length it’s very important to watch out for trailing spaces in the data and to ensure an eol character at the end of every line. The download file is correctly formatted. The final schema definition can be downloaded at the following link Download Completed Schema Definition   - Save the inputData.txt file to a known location like the xsd folder in your project. - Save the inputData_6.xsd file to the xsd folder in your project. - At step 1 in the Native Format Builder wizard  (as shown above) check the “Edit existing” radio button,    then browse and select the inputData_6.xsd file - At step 2 of the Format Builder configuration Wizard (as shown above) supply the path and filename for    the inputData.txt file. - You can then proceed to the test page and run a test. - Remember the wizard bug will drop the lookAhead and lookFor attributes,  you will need to manually add   nxsd:lookAhead="32" nxsd:lookFor="."    after the maxOccurs attribute of the item element in the   LogicalOrderRecord Complex Type.  (as shown above)   Good Luck with your Format Project

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• Why would I need a using statement to Libary B extn methods, if they're used in Library A & it's Li

  - by Greg

  Hi, I have: Main Program Class - uses Library A Library A - has partial classes which mix in methods from Library B Library B - mix in methods & interfaces Why would I need a using statement to LibaryB just to get their extension methods working in the main class? That is given that it's Library B that defines the classes that will be extended. EDIT - Except from code // *** PROGRAM *** using TopologyDAL; using Topology; // *** THIS WAS NEEDED TO GET EXTN METHODS APPEARING *** class Program { static void Main(string[] args) { var context = new Model1Container(); Node myNode; // ** trying to get myNode mixin methods to appear seems to need using line to point to Library B *** } } // ** LIBRARY A namespace TopologyDAL { public partial class Node { // Auto generated from EF } public partial class Node : INode<int> // to add extension methods from Library B { public int Key } } // ** LIBRARY B namespace ToplogyLibrary { public static class NodeExtns { public static void FromNodeMixin<T>(this INode<T> node) { // XXXX } } public interface INode<T> { // Properties T Key { get; } // Methods } }

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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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• Getting Current Native Thread

  - by Ricardo Peres

  The native OS threads running in the current process are exposed through the Threads property of the Process class. Please note that this is not the same as a managed thread, these are the actual native threads running on the operating system. In order to get a pointer to the current executing thread, we must use P/Invoke. Here's how we do it: [DllImport("kernel32.dll")] public static extern UInt32 GetCurrentThreadId(); UInt32 id = GetCurrentThreadId(); ProcessThread thread = Process.GetCurrentProcess().Threads.Cast().Where(t = t.Id == id).Single(); SyntaxHighlighter.config.clipboardSwf = 'http://alexgorbatchev.com/pub/sh/2.0.320/scripts/clipboard.swf'; SyntaxHighlighter.brushes.CSharp.aliases = ['c#', 'c-sharp', 'csharp']; SyntaxHighlighter.all();

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• Corona SDK (Lua) vs Native Obj-C for iPhone only word puzzle type game [closed]

  - by dodgy_coder

  I am trying to decide on whether to use the Corona SDK & Lua versus native Objective-C to develop an iOS app. This will be the first game on any smartphone I have developed and so its not that ambitious - a single player word puzzle type game - something sort of like scrabble. The advantages of Corona I can see are: Lua is probably easier to learn than Obj-C (shorter learning curve) meaning a possibly quicker development time Possibility to port to Android once its finished Advantages of native Obj-C are: Access to all and latest features of iOS More / faster available libraries Has anyone made this decision before? Are there any major advantages or disadvantages I've missed or got wrong here? Thanks.

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• Handbrake-powered VidCoder gets a native 64-bit version

  A while back, VidCoder -- the Windows video disc ripping program -- added support for Blu-ray discs. With Handbrake's engine under the hood, VidCoder offers an easy-to-use interface and simple batch processing of your video files. With the release of version 0.8, there's also now a native 64-bit version for those of you running Windows x64. A number of stability tweaks have also been introduced. As Baz pointed out in our comments last time, VidCoder is particular useful on netbooks. If you've got a 1024x600 screen, Handbrake may not even launch for you -- but VidCoder will fire up just fine. Take the new 64-bit version for a spin, and share your thoughts in the comments. Download VidCoderHandbrake-powered VidCoder gets a native 64-bit version originally appeared on Download Squad on Fri, 07 Jan 2011 17:00:00 EST. Please see our terms for use of feeds.Permalink | Email this | Comments

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• HTML5 or Native Android/iOS application?

  - by Dimitris

  I would like to hear your opinion on this debate. I want to build a mobile application which will interact with a server and I was wondering what's the best way to do it. Build the entire application using the HTML5 technology and then just create native "browsing" apps for Android/iOS or to build the Android/iOS apps from scratch? Using the HTML5 will save considerable amounts of time but I don't know if the result will be equally good in both platforms. Building native apps will take much more time but the result will be definitely good. What do you think?

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• Mobile Compatibility: traditional website look vs native application ?

  - by Siddiqui

  I have a question related to mobile compatible websites, I have seen two type of websites One in which they adopt traditional website look and adjust website according to mobile screen, if they have lot of information which can not be adjust according to screen then they expand the height of page, so that user can scroll the page to see more information... In the second approach they used native application look means use navigation-bar, tab-bar, tool-bar, scroll-view just like in native applications. Height and width of page adjust according to screen size, if they have more information then they use scroll-view etc... My question is: which approach is better then other, in which approach you feel more comfortable to use website.

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• C#: Adding Functionality to 3rd Party Libraries With Extension Methods

  - by James Michael Hare

  Ever have one of those third party libraries that you love but it's missing that one feature or one piece of syntactical candy that would make it so much more useful?  This, I truly think, is one of the best uses of extension methods.  I began discussing extension methods in my last post (which you find here) where I expounded upon what I thought were some rules of thumb for using extension methods correctly.  As long as you keep in line with those (or similar) rules, they can often be useful for adding that little extra functionality or syntactical simplification for a library that you have little or no control over. Oh sure, you could take an open source project, download the source and add the methods you want, but then every time the library is updated you have to re-add your changes, which can be cumbersome and error prone.  And yes, you could possibly extend a class in a third party library and override features, but that's only if the class is not sealed, static, or constructed via factories. This is the perfect place to use an extension method!  And the best part is, you and your development team don't need to change anything!  Simply add the using for the namespace the extensions are in! So let's consider this example.  I love log4net!  Of all the logging libraries I've played with, it, to me, is one of the most flexible and configurable logging libraries and it performs great.  But this isn't about log4net, well, not directly.  So why would I want to add functionality?  Well, it's missing one thing I really want in the ILog interface: ability to specify logging level at runtime. For example, let's say I declare my ILog instance like so:     using log4net;     public class LoggingTest     {         private static readonly ILog _log = LogManager.GetLogger(typeof(LoggingTest));         ...     }     If you don't know log4net, the details aren't important, just to show that the field _log is the logger I have gotten from log4net. So now that I have that, I can log to it like so:     _log.Debug("This is the lowest level of logging and just for debugging output.");     _log.Info("This is an informational message.  Usual normal operation events.");     _log.Warn("This is a warning, something suspect but not necessarily wrong.");     _log.Error("This is an error, some sort of processing problem has happened.");     _log.Fatal("Fatals usually indicate the program is dying hideously."); And there's many flavors of each of these to log using string formatting, to log exceptions, etc.  But one thing there isn't: the ability to easily choose the logging level at runtime.  Notice, the logging levels above are chosen at compile time.  Of course, you could do some fun stuff with lambdas and wrap it, but that would obscure the simplicity of the interface.  And yes there is a Logger property you can dive down into where you can specify a Level, but the Level properties don't really match the ILog interface exactly and then you have to manually build a LogEvent and... well, it gets messy.  I want something simple and sexy so I can say:     _log.Log(someLevel, "This will be logged at whatever level I choose at runtime!");     Now, some purists out there might say you should always know what level you want to log at, and for the most part I agree with them.  For the most party the ILog interface satisfies 99% of my needs.  In fact, for most application logging yes you do always know the level you will be logging at, but when writing a utility class, you may not always know what level your user wants. I'll tell you, one of my favorite things is to write reusable components.  If I had my druthers I'd write framework libraries and shared components all day!  And being able to easily log at a runtime-chosen level is a big need for me.  After all, if I want my code to really be re-usable, I shouldn't force a user to deal with the logging level I choose. One of my favorite uses for this is in Interceptors -- I'll describe Interceptors in my next post and some of my favorites -- for now just know that an Interceptor wraps a class and allows you to add functionality to an existing method without changing it's signature.  At the risk of over-simplifying, it's a very generic implementation of the Decorator design pattern. So, say for example that you were writing an Interceptor that would time method calls and emit a log message if the method call execution time took beyond a certain threshold of time.  For instance, maybe if your database calls take more than 5,000 ms, you want to log a warning.  Or if a web method call takes over 1,000 ms, you want to log an informational message.  This would be an excellent use of logging at a generic level. So here was my personal wish-list of requirements for my task: Be able to determine if a runtime-specified logging level is enabled. Be able to log generically at a runtime-specified logging level. Have the same look-and-feel of the existing Debug, Info, Warn, Error, and Fatal calls.    Having the ability to also determine if logging for a level is on at runtime is also important so you don't spend time building a potentially expensive logging message if that level is off.  Consider an Interceptor that may log parameters on entrance to the method.  If you choose to log those parameter at DEBUG level and if DEBUG is not on, you don't want to spend the time serializing those parameters. Now, mine may not be the most elegant solution, but it performs really well since the enum I provide all uses contiguous values -- while it's never guaranteed, contiguous switch values usually get compiled into a jump table in IL which is VERY performant - O(1) - but even if it doesn't, it's still so fast you'd never need to worry about it. So first, I need a way to let users pass in logging levels.  Sure, log4net has a Level class, but it's a class with static members and plus it provides way too many options compared to ILog interface itself -- and wouldn't perform as well in my level-check -- so I define an enum like below.     namespace Shared.Logging.Extensions     {         // enum to specify available logging levels.         public enum LoggingLevel         {             Debug,             Informational,             Warning,             Error,             Fatal         }     } Now, once I have this, writing the extension methods I need is trivial.  Once again, I would typically /// comment fully, but I'm eliminating for blogging brevity:     namespace Shared.Logging.Extensions     {         // the extension methods to add functionality to the ILog interface         public static class LogExtensions         {             // Determines if logging is enabled at a given level.             public static bool IsLogEnabled(this ILog logger, LoggingLevel level)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         return logger.IsDebugEnabled;                     case LoggingLevel.Informational:                         return logger.IsInfoEnabled;                     case LoggingLevel.Warning:                         return logger.IsWarnEnabled;                     case LoggingLevel.Error:                         return logger.IsErrorEnabled;                     case LoggingLevel.Fatal:                         return logger.IsFatalEnabled;                 }                                 return false;             }             // Logs a simple message - uses same signature except adds LoggingLevel             public static void Log(this ILog logger, LoggingLevel level, object message)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         logger.Debug(message);                         break;                     case LoggingLevel.Informational:                         logger.Info(message);                         break;                     case LoggingLevel.Warning:                         logger.Warn(message);                         break;                     case LoggingLevel.Error:                         logger.Error(message);                         break;                     case LoggingLevel.Fatal:                         logger.Fatal(message);                         break;                 }             }             // Logs a message and exception to the log at specified level.             public static void Log(this ILog logger, LoggingLevel level, object message, Exception exception)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         logger.Debug(message, exception);                         break;                     case LoggingLevel.Informational:                         logger.Info(message, exception);                         break;                     case LoggingLevel.Warning:                         logger.Warn(message, exception);                         break;                     case LoggingLevel.Error:                         logger.Error(message, exception);                         break;                     case LoggingLevel.Fatal:                         logger.Fatal(message, exception);                         break;                 }             }             // Logs a formatted message to the log at the specified level.              public static void LogFormat(this ILog logger, LoggingLevel level, string format,                                          params object[] args)             {                 switch (level)                 {                     case LoggingLevel.Debug:                         logger.DebugFormat(format, args);                         break;                     case LoggingLevel.Informational:                         logger.InfoFormat(format, args);                         break;                     case LoggingLevel.Warning:                         logger.WarnFormat(format, args);                         break;                     case LoggingLevel.Error:                         logger.ErrorFormat(format, args);                         break;                     case LoggingLevel.Fatal:                         logger.FatalFormat(format, args);                         break;                 }             }         }     } So there it is!  I didn't have to modify the log4net source code, so if a new version comes out, i can just add the new assembly with no changes.  I didn't have to subclass and worry about developers not calling my sub-class instead of the original.  I simply provide the extension methods and it's as if the long lost extension methods were always a part of the ILog interface! Consider a very contrived example using the original interface:     // using the original ILog interface     public class DatabaseUtility     {         private static readonly ILog _log = LogManager.Create(typeof(DatabaseUtility));                 // some theoretical method to time         IDataReader Execute(string statement)         {             var timer = new System.Diagnostics.Stopwatch();                         // do DB magic                                    // this is hard-coded to warn, if want to change at runtime tough luck!             if (timer.ElapsedMilliseconds > 5000 && _log.IsWarnEnabled)             {                 _log.WarnFormat("Statement {0} took too long to execute.", statement);             }             ...         }     }     Now consider this alternate call where the logging level could be perhaps a property of the class          // using the original ILog interface     public class DatabaseUtility     {         private static readonly ILog _log = LogManager.Create(typeof(DatabaseUtility));                 // allow logging level to be specified by user of class instead         public LoggingLevel ThresholdLogLevel { get; set; }                 // some theoretical method to time         IDataReader Execute(string statement)         {             var timer = new System.Diagnostics.Stopwatch();                         // do DB magic                                    // this is hard-coded to warn, if want to change at runtime tough luck!             if (timer.ElapsedMilliseconds > 5000 && _log.IsLogEnabled(ThresholdLogLevel))             {                 _log.LogFormat(ThresholdLogLevel, "Statement {0} took too long to execute.",                     statement);             }             ...         }     } Next time, I'll show one of my favorite uses for these extension methods in an Interceptor.

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• How to pass a file (read from Java) most effectively to a native method?

  - by soc

  Hi, I have approx. 30000 files (1MB each) which I want to put into a native method, which requires just an byte array and the size of it as arguments. I looked through some examples and benchmarks (like http://nadeausoftware.com/articles/2008/02/java_tip_how_read_files_quickly) but all of them do some other fancy things. Basically I don't care about the contents of the file, I don't want to access something in that file or the byte array or do anything else with it. I just want to put a file into a native method which accepts an byte array as fast as possible. At the moment I'm using RandomAccessFile, but that's horribly slow (10MB/s). Is there anything like byte[] readTheWholeFile(File file){ ... } which I could put into native void fancyCMethod(readTheWholeFile(myFile), myFile.length()) What would you suggest?

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• How can I make a career in Formal Methods programming in USA?

  - by A5al Andy

  I've found that my (USA) professors recoil with a near-disgust when I ask them about how to pursue a career in Formal Methods programming. They say, "Oh, that stuff! That stuff is anal. You don't need that European POS to get a job." I'm sure I'll get a job without it, but Formal Methods interests me so much that I bet I'd like to make a career of it. I'd like to learn about Formal Methods at an American University and then work in that field here. I've found that even professors at more important universities than mine don't seem to welcome Formal Methods. Almost all FM research project webpages are semi-abandoned and moldering. Europe is where the action seems to be for this. Can anyone suggest a plan of attack, and along the way explain the antipathy to Formal Methods in the US? I'm a sophomore at a public university in the South.

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• Creating Asynchronous Methods in EJB 3.1

  - by cindo

  Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} OBE of the Month: Creating Asynchronous Methods in EJB 3.1 This OBE covers creating an EJB 3.1 application that demonstrates the use of the @Asynchronous annotation in an Enterprise Java Bean (EJB) class or specific method. In this tutorial, you will create a Java EE 6 Web Application and add the following components to it - a Stateless Session Bean with two asynchronous methods. You define a Servlet to call the asynchronous methods and to keep track of the invocation and completion times to demonstrate the asynchronous nature of the method calls. The index.jsp will contain a form with a submit button, Run allowing you to execute the application. The form will submit to the Servlet which invokes the asynchronous methods defined in the session bean and the response is re-directed to response.jsp. Information about the asynchronous handling procedure is displayed to users. From this information, users will notice that the invoker thread and the called asynchronous thread are working concurrently. Check out this new OBE on the Oracle Learning Library: Creating Asynchronous Methods in EJB 3.1. This OBE is part of the new EJB 3.1 New Features Series. Related OBE’s that might interest you: Creating a No-Interface View Session Bean and Packaging in a WAR File Creating and Accessing a Session Bean in a  Web Application

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• OpenGL 2 on Android: native window

  - by ThreaderSlash

  According to OGLES specification, we have the following definition: EGLSurface eglCreateWindowSurface(EGLDisplay display, EGLConfig config, NativeWindowType native_window, EGLint const * attrib_list) More details, here: http://www.khronos.org/opengles/documentation/opengles1_0/html/eglCreateWindowSurface.html And also by definition: int32_t ANativeWindow_setBuffersGeometry(ANativeWindow* window, int32_t width, int32_t height, int32_t format); More details, here: http://mobilepearls.com/labs/native-android-api I am running Android Native App on OGLES 2 and debugging it in a Samsung Nexus device. For setting up the 3D scene graph environment, the following variables are defined: struct android_app { ... ANativeWindow* window; }; android_app* mApplication; ... mApplication=&pApplication; And to initialize the App, we run the commands in the code: ANativeWindow_setBuffersGeometry(mApplication->window, 0, 0, lFormat); mSurface = eglCreateWindowSurface(mDisplay, lConfig, mApplication->window, NULL); Funny to say is that, the command ANativeWindow_setBuffersGeometry behaves as expected and works fine according to its definition, accepting all the parameters sent to it. But the eglCreateWindowSurface does no accept the parameter mApplication-window, as it should accept according to its definition. Instead, it looks for the following input: EGLNativeWindowType hWnd; mSurface = eglCreateWindowSurface(mDisplay,lConfig,hWnd,NULL); As an alternative, I considered to use instead: NativeWindowType hWnd=android_createDisplaySurface(); But debugger says: Function 'android_createDisplaySurface' could not be resolved Can someone tell if there is a way to convert mApplication-window? In a way that the data from the android_app get accepted to the window surface?

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• MetroTwit is a Sleek Native Twitter Client for Your Windows System

  - by Asian Angel

  Do you love the new Metro design and need a native Twitter desktop client for your Windows system too? Then you may want to have a look at MetroTwit. When you kick-start the MetroTwit exe file it will download the necessary .NET Framework components if you do not already have them installed. Once that is finished it will then download the MetroTwit installation files to ensure that you have the latest release. MetroTwit will automatically start once the setup process has finished. From there you can quickly modify the layout (i.e. visible columns, etc.), theme, and other UI features to make MetroTwit right at home on your system. UI features visible in the screenshot above: Top: Access the Settings in the center at the top of the window Bottom: Add Column, Lists, Refresh, Tweet Window, Search Twitter, User Profile, and Twitter Trends As you can see here the Settings are laid out nicely and very easy to navigate through. Features of MetroTwit: Drag and drop image support TwitLonger support for longer tweets Tweet breadcrumbs Infinite scrolling Auto-complete for user names and hashtags Themes and accents Resizable and reorderable columns What The Trend access URL shortening and previews Windows 7 Taskbar integration Quick-glance notifications Flawless high DPI support Note: Requires .NET Framework 4.0. Download MetroTwit [via DownloadSquad] Latest Features How-To Geek ETC What Can Super Mario Teach Us About Graphics Technology? Windows 7 Service Pack 1 is Released: But Should You Install It? How To Make Hundreds of Complex Photo Edits in Seconds With Photoshop Actions How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) How To Remove People and Objects From Photographs In Photoshop MetroTwit is a Sleek Native Twitter Client for Your Windows System Make Efficient Use of Tab Bar Space by Customizing Tab Width in Firefox See the Geeky Work Done Behind the Scenes to Add Sounds to Movies [Video] Use a Crayon to Enhance Engraved Lettering on Electronics Adult Swim Brings Their Programming Lineup to iOS Devices Feel the Chill of the South Atlantic with the Antarctica Theme for Windows 7

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• Manager/Container class vs static class methods

  - by Ben

  Suppose I a have a Widget class that is part of a framework used independently by many applications. I create Widget instances in many situations and their lifetimes vary. In addition to Widget's instance specified methods, I would like to be able to perform the follow class wide operations: Find a single Widget instance based on a unique id Iterate over the list of all Widgets Remove a widget from the set of all widgets In order support these operations, I have been considering two approaches: Container class - Create some container or manager class, WidgetContainer, which holds a list of all Widget instances, support iteration and provides methods for Widget addition, removal and lookup. For example in C#: public class WidgetContainer : IEnumerable<Widget { public void AddWidget(Widget); public Widget GetWidget(WidgetId id); public void RemoveWidget(WidgetId id); } Static class methods - Add static class methods to Widget. For example: public class Widget { public Widget(WidgetId id); public static Widget GetWidget(WidgetId id); public static void RemoveWidget(WidgetId id); public static IEnumerable<Widget AllWidgets(); } Using a container class has the added problem of how to access the container class. Make it a singleton?..yuck! Create some World object that provides access to all such container classes? I have seen many frameworks that use the container class approach, so what is the general consensus?

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• Give Chromium-Based Browser Desktop Notifications a Native System Look in Ubuntu

  - by Asian Angel

  Desktop notifications from Chromium-based browsers are an awesome feature, but they do not blend in well at all with the native system theming in Ubuntu. Now you can fix that small problem using the wonderful Chromify-OSD extension created by Marco Ceppi. Once you get the extension installed you can give it a quick test run using the link and information we have listed below. As you can see in the image above the new notification style looks absolutely wonderful. Chromify-OSD (Chrome Web Store) [via OMG! Ubuntu!] You can test the new look of the notifications for yourself using the following webpage. Keep in mind that the extension needs to be installed first before this will work though. Note: Enter the following image URL into the Icon Blank (http://www.rgraph.net/images/logo.png) or the URL for an appropriate image, otherwise the notification may not work properly during your test. Chromify Sample HTML5 Notification Test Page The wallpaper shown in the screenshot above can be downloaded here: anime sport [DesktopNexus] Latest Features How-To Geek ETC How to Enable User-Specific Wireless Networks in Windows 7 How to Use Google Chrome as Your Default PDF Reader (the Easy Way) How To Remove People and Objects From Photographs In Photoshop Ask How-To Geek: How Can I Monitor My Bandwidth Usage? Internet Explorer 9 RC Now Available: Here’s the Most Interesting New Stuff Here’s a Super Simple Trick to Defeating Fake Anti-Virus Malware The Citroen GT – An Awesome Video Game Car Brought to Life [Video] Final Man vs. Machine Round of Jeopardy Unfolds; Watson Dominates Give Chromium-Based Browser Desktop Notifications a Native System Look in Ubuntu Chrome Time Track Is a Simple Task Time Tracker Google Sky Map Turns Your Android Phone into a Digital Telescope Walking Through a Seaside Village Wallpaper

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• SOA Starting Point: Methods for Service Identification and Definition

  As more and more companies start to incorporate a Service Oriented Architectural design approach into their existing enterprise systems, it creates the need for a standardized integration technology. One common technology used by companies is an Enterprise Service Bus (ESB). An ESB, as defined by Progress Software, connects and mediates all communications and interactions between services. In essence an ESB is a form of middleware that allows services to communicate with one another regardless of framework, environment, or location. With the emergence of ESB, a new emphasis is now being placed on approaches that can be used to determine what Web services should be built. In addition, what order should these services be built? In May 2011, SOA Magazine published an article that identified 10 common methods for identifying and defining services. SOA’s Ten Common Methods for Service Identification and Definition: Business Process Decomposition Business Functions Business Entity Objects Ownership and Responsibility Goal-Driven Component-Based Existing Supply (Bottom-Up) Front-Office Application Usage Analysis Infrastructure Non-Functional Requirements  Each of these methods provides various pros and cons in regards to their use within the design process. I personally feel that during a design process, multiple methodologies should be used in order to accurately define a design for a system or enterprise system. Personally, I like to create a custom cocktail derived from combining these methodologies in order to ensure that my design fits with the project’s and business’s needs while still following development standards and guidelines. Of these ten methods, I am particularly fond of Business Process Decomposition, Business Functions, Goal-Driven, Component-Based, and routinely use them in my designs.  Works Cited Hubbers, J.-W., Ligthart, A., & Terlouw , L. (2007, 12 10). Ten Ways to Identify Services. Retrieved from SOA Magazine: http://www.soamag.com/I13/1207-1.php Progress.com. (2011, 10 30). ESB ARCHITECTURE AND LIFECYCLE DEFINITION. Retrieved from Progress.com: http://web.progress.com/en/esb-architecture-lifecycle-definition.html

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• Inside the DLR – Invoking methods

  - by Simon Cooper

  So, we’ve looked at how a dynamic call is represented in a compiled assembly, and how the dynamic lookup is performed at runtime. The last piece of the puzzle is how the resolved method gets invoked, and that is the subject of this post. Invoking methods As discussed in my previous posts, doing a full lookup and bind at runtime each and every single time the callsite gets invoked would be far too slow to be usable. The results obtained from the callsite binder must to be cached, along with a series of conditions to determine whether the cached result can be reused. So, firstly, how are the conditions represented? These conditions can be anything; they are determined entirely by the semantics of the language the binder is representing. The binder has to be able to return arbitary code that is then executed to determine whether the conditions apply or not. Fortunately, .NET 4 has a neat way of representing arbitary code that can be easily combined with other code – expression trees. All the callsite binder has to return is an expression (called a ‘restriction’) that evaluates to a boolean, returning true when the restriction passes (indicating the corresponding method invocation can be used) and false when it does’t. If the bind result is also represented in an expression tree, these can be combined easily like so: if ([restriction is true]) { [invoke cached method] } Take my example from my previous post: public class ClassA { public static void TestDynamic() { CallDynamic(new ClassA(), 10); CallDynamic(new ClassA(), "foo"); } public static void CallDynamic(dynamic d, object o) { d.Method(o); } public void Method(int i) {} public void Method(string s) {} } When the Method(int) method is first bound, along with an expression representing the result of the bind lookup, the C# binder will return the restrictions under which that bind can be reused. In this case, it can be reused if the types of the parameters are the same: if (thisArg.GetType() == typeof(ClassA) && arg1.GetType() == typeof(int)) { thisClassA.Method(i); } Caching callsite results So, now, it’s up to the callsite to link these expressions returned from the binder together in such a way that it can determine which one from the many it has cached it should use. This caching logic is all located in the System.Dynamic.UpdateDelegates class. It’ll help if you’ve got this type open in a decompiler to have a look yourself. For each callsite, there are 3 layers of caching involved: The last method invoked on the callsite. All methods that have ever been invoked on the callsite. All methods that have ever been invoked on any callsite of the same type. We’ll cover each of these layers in order Level 1 cache: the last method called on the callsite When a CallSite<T> object is first instantiated, the Target delegate field (containing the delegate that is called when the callsite is invoked) is set to one of the UpdateAndExecute generic methods in UpdateDelegates, corresponding to the number of parameters to the callsite, and the existance of any return value. These methods contain most of the caching, invoke, and binding logic for the callsite. The first time this method is invoked, the UpdateAndExecute method finds there aren’t any entries in the caches to reuse, and invokes the binder to resolve a new method. Once the callsite has the result from the binder, along with any restrictions, it stitches some extra expressions in, and replaces the Target field in the callsite with a compiled expression tree similar to this (in this example I’m assuming there’s no return value): if ([restriction is true]) { [invoke cached method] return; } if (callSite._match) { _match = false; return; } else { UpdateAndExecute(callSite, arg0, arg1, ...); } Woah. What’s going on here? Well, this resulting expression tree is actually the first level of caching. The Target field in the callsite, which contains the delegate to call when the callsite is invoked, is set to the above code compiled from the expression tree into IL, and then into native code by the JIT. This code checks whether the restrictions of the last method that was invoked on the callsite (the ‘primary’ method) match, and if so, executes that method straight away. This means that, the next time the callsite is invoked, the first code that executes is the restriction check, executing as native code! This makes this restriction check on the primary cached delegate very fast. But what if the restrictions don’t match? In that case, the second part of the stitched expression tree is executed. What this section should be doing is calling back into the UpdateAndExecute method again to resolve a new method. But it’s slightly more complicated than that. To understand why, we need to understand the second and third level caches. Level 2 cache: all methods that have ever been invoked on the callsite When a binder has returned the result of a lookup, as well as updating the Target field with a compiled expression tree, stitched together as above, the callsite puts the same compiled expression tree in an internal list of delegates, called the rules list. This list acts as the level 2 cache. Why use the same delegate? Stitching together expression trees is an expensive operation. You don’t want to do it every time the callsite is invoked. Ideally, you would create one expression tree from the binder’s result, compile it, and then use the resulting delegate everywhere in the callsite. But, if the same delegate is used to invoke the callsite in the first place, and in the caches, that means each delegate needs two modes of operation. An ‘invoke’ mode, for when the delegate is set as the value of the Target field, and a ‘match’ mode, used when UpdateAndExecute is searching for a method in the callsite’s cache. Only in the invoke mode would the delegate call back into UpdateAndExecute. In match mode, it would simply return without doing anything. This mode is controlled by the _match field in CallSite<T>. The first time the callsite is invoked, _match is false, and so the Target delegate is called in invoke mode. Then, if the initial restriction check fails, the Target delegate calls back into UpdateAndExecute. This method sets _match to true, then calls all the cached delegates in the rules list in match mode to try and find one that passes its restrictions, and invokes it. However, there needs to be some way for each cached delegate to inform UpdateAndExecute whether it passed its restrictions or not. To do this, as you can see above, it simply re-uses _match, and sets it to false if it did not pass the restrictions. This allows the code within each UpdateAndExecute method to check for cache matches like so: foreach (T cachedDelegate in Rules) { callSite._match = true; cachedDelegate(); // sets _match to false if restrictions do not pass if (callSite._match) { // passed restrictions, and the cached method was invoked // set this delegate as the primary target to invoke next time callSite.Target = cachedDelegate; return; } // no luck, try the next one... } Level 3 cache: all methods that have ever been invoked on any callsite with the same signature The reason for this cache should be clear – if a method has been invoked through a callsite in one place, then it is likely to be invoked on other callsites in the codebase with the same signature. Rather than living in the callsite, the ‘global’ cache for callsite delegates lives in the CallSiteBinder class, in the Cache field. This is a dictionary, typed on the callsite delegate signature, providing a RuleCache<T> instance for each delegate signature. This is accessed in the same way as the level 2 callsite cache, by the UpdateAndExecute methods. When a method is matched in the global cache, it is copied into the callsite and Target cache before being executed. Putting it all together So, how does this all fit together? Like so (I’ve omitted some implementation & performance details): That, in essence, is how the DLR performs its dynamic calls nearly as fast as statically compiled IL code. Extensive use of expression trees, compiled to IL and then into native code. Multiple levels of caching, the first of which executes immediately when the dynamic callsite is invoked. And a clever re-use of compiled expression trees that can be used in completely different contexts without being recompiled. All in all, a very fast and very clever reflection caching mechanism.

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• OpenGL ES 2 on Android: native window

  - by ThreaderSlash

  According to OGLES specification, we have the following definition: EGLSurface eglCreateWindowSurface(EGLDisplay display, EGLConfig config, NativeWindowType native_window, EGLint const * attrib_list) More details, here: http://www.khronos.org/opengles/documentation/opengles1_0/html/eglCreateWindowSurface.html And also by definition: int32_t ANativeWindow_setBuffersGeometry(ANativeWindow* window, int32_t width, int32_t height, int32_t format); More details, here: http://mobilepearls.com/labs/native-android-api I am running Android Native App on OGLES 2 and debugging it in a Samsung Nexus device. For setting up the 3D scene graph environment, the following variables are defined: struct android_app { ... ANativeWindow* window; }; android_app* mApplication; ... mApplication=&pApplication; And to initialize the App, we run the commands in the code: ANativeWindow_setBuffersGeometry(mApplication->window, 0, 0, lFormat); mSurface = eglCreateWindowSurface(mDisplay, lConfig, mApplication->window, NULL); Funny to say is that, the command ANativeWindow_setBuffersGeometry behaves as expected and works fine according to its definition, accepting all the parameters sent to it. But the eglCreateWindowSurface does no accept the parameter mApplication-window, as it should accept according to its definition. Instead, it looks for the following input: EGLNativeWindowType hWnd; mSurface = eglCreateWindowSurface(mDisplay,lConfig,hWnd,NULL); As an alternative, I considered to use instead: NativeWindowType hWnd=android_createDisplaySurface(); But debugger says: Function 'android_createDisplaySurface' could not be resolved Is 'android_createDisplaySurface' compatible only for OGLES 1 and not for OGLES 2? Can someone tell if there is a way to convert mApplication-window? In a way that the data from the android_app get accepted to the window surface?

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• Breaking up classes and methods into smaller units

  - by micahhoover

  During code reviews a couple devs have recommended I break up my methods into smaller methods. Their justification was (1) increased readability and (2) the back trace that comes back from production showing the method name is more specific to the line of code that failed. There may have also been some colorful words about functional programming. Additionally I think I may have failed an interview a while back because I didn't give an acceptable answer about when to break things up. My inclination is that when I see a bunch of methods in a class or across a bunch of files, it isn't clear to me how they flow together, and how many times each one gets called. I don't really have a good feel for the linearity of it as quickly just by eye-balling it. The other thing is a lot of people seem to place a premium of organization over content (e.g. 'Look at how organized my sock drawer is!' Me: 'Overall, I think I can get to my socks faster if you count the time it took to organize them'). Our business requirements are not very stable. I'm afraid that if the classes/methods are very granular it will take longer to refactor to requirement changes. I'm not sure how much of a factor this should be. Anyway, computer science is part art / part science, but I'm not sure how much this applies to this issue.

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• Should we rename overloaded methods?

  - by Mik378

  Assume an interface containing these methods : Car find(long id); List<Car> find(String model); Is it better to rename them like this? Car findById(long id); List findByModel(String model); Indeed, any developer who use this API won't need to look at the interface for knowing possible arguments of initial find() methods. So my question is more general : What is the benefit of using overloaded methods in code since it reduce readability?

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• Google's Going Native in Chrome With SDK

  New open source Native Client SDK debuts for Chrome, bringing C and C++ to the Web. But is it just another form of vendor lock-in?

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• Native PHP vs exec()

  - by resting

  Just wondering, assuming no security issues, that is, you're in total control of the command passed to exec(), is there a difference (in terms of speed or standards) between using exec() vs native PHP? Example just to name a few use cases: Using the DirectoryIterator vs exec(ls -1, $output), to list all files. List 100 files from the 99th file onwards (that is, file 100 to 199) Count total number of files in directory.

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• Configuring Fed Authentication Methods in OIF / IdP

  - by Damien Carru

  In this article, I will provide examples on how to configure OIF/IdP to map OAM Authentication Schemes to Federation Authentication Methods, based on the concepts introduced in my previous entry. I will show examples for the three protocols supported by OIF: SAML 2.0 SSO SAML 1.1 SSO OpenID 2.0 Enjoy the reading! Configuration As I mentioned in my previous article, mapping Federation Authentication Methods to OAM Authentication Schemes is protocol dependent, since the methods are defined in the various protocols (SAML 2.0, SAML 1.1, OpenID 2.0). As such, the WLST commands to set those mappings will involve: Either the SP Partner Profile and affect all Partners referencing that profile, which do not override the Federation Authentication Method to OAM Authentication Scheme mappings Or the SP Partner entry, which will only affect the SP Partner It is important to note that if an SP Partner is configured to define one or more Federation Authentication Method to OAM Authentication Scheme mappings, then all the mappings defined in the SP Partner Profile will be ignored. WLST Commands The two OIF WLST commands that can be used to define mapping Federation Authentication Methods to OAM Authentication Schemes are: addSPPartnerProfileAuthnMethod() to define a mapping on an SP Partner Profile, taking as parameters: The name of the SP Partner Profile The Federation Authentication Method The OAM Authentication Scheme name addSPPartnerAuthnMethod() to define a mapping on an SP Partner , taking as parameters: The name of the SP Partner The Federation Authentication Method The OAM Authentication Scheme name Note: I will discuss in a subsequent article the other parameters of those commands. In the next sections, I will show examples on how to use those methods: For SAML 2.0, I will configure the SP Partner Profile, that will apply all the mappings to SP Partners referencing this profile, unless they override mapping definition For SAML 1.1, I will configure the SP Partner. For OpenID 2.0, I will configure the SP/RP Partner SAML 2.0 Test Setup In this setup, OIF is acting as an IdP and is integrated with a remote SAML 2.0 SP partner identified by AcmeSP. In this test, I will perform Federation SSO with OIF/IdP configured to: Use LDAPScheme as the Authentication Scheme Use BasicScheme as the Authentication Scheme Map BasicSessionScheme  to  the urn:oasis:names:tc:SAML:2.0:ac:classes:Password Federation Authentication Method Use OAMLDAPPluginAuthnScheme as the Authentication Scheme Map OAMLDAPPluginAuthnScheme to  the urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport Federation Authentication Method LDAPScheme as Authentication Scheme Using the OOTB settings regarding user authentication in OAM, the user will be challenged via a FORM based login page based on the LDAPScheme. Also the default Federation Authentication Method mappings configuration maps only the urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport to LDAPScheme (also marked as the default scheme used for authentication), FAAuthScheme, BasicScheme and BasicFAScheme. After authentication via FORM, OIF/IdP would issue an Assertion similar to: <samlp:Response ...>    <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>    <samlp:Status>        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>    </samlp:Status>    <saml:Assertion ...>        <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>        <dsig:Signature>            ...        </dsig:Signature>        <saml:Subject>            <saml:NameID ...>[email protected]</saml:NameID>            <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">                <saml:SubjectConfirmationData .../>            </saml:SubjectConfirmation>        </saml:Subject>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z">            <saml:AuthnContext>                <saml:AuthnContextClassRef>                   urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport                </saml:AuthnContextClassRef>            </saml:AuthnContext>        </saml:AuthnStatement>    </saml:Assertion></samlp:Response> BasicScheme as Authentication Scheme For this test, I will switch the default Authentication Scheme for the SP Partner Profile to BasicScheme instead of LDAPScheme. I will use the OIF WLST setSPPartnerProfileDefaultScheme() command and specify which scheme to be used as the default for the SP Partner Profile referenced by AcmeSP (which is saml20-sp-partner-profile in this case: getFedPartnerProfile("AcmeSP", "sp") ): Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the setSPPartnerProfileDefaultScheme() command:setSPPartnerProfileDefaultScheme("saml20-sp-partner-profile", "BasicScheme") Exit the WLST environment:exit() The user will now be challenged via HTTP Basic Authentication defined in the BasicScheme for AcmeSP. Also, as noted earlier, the default Federation Authentication Method mappings configuration maps only the urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport to LDAPScheme (also marked as the default scheme used for authentication), FAAuthScheme, BasicScheme and BasicFAScheme. After authentication via HTTP Basic Authentication, OIF/IdP would issue an Assertion similar to: <samlp:Response ...>    <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>    <samlp:Status>        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>    </samlp:Status>    <saml:Assertion ...>        <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>        <dsig:Signature>            ...        </dsig:Signature>        <saml:Subject>            <saml:NameID ...>[email protected]</saml:NameID>            <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">                <saml:SubjectConfirmationData .../>            </saml:SubjectConfirmation>        </saml:Subject>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z">            <saml:AuthnContext>                <saml:AuthnContextClassRef>                   urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport                </saml:AuthnContextClassRef>            </saml:AuthnContext>        </saml:AuthnStatement>    </saml:Assertion></samlp:Response> Mapping BasicScheme To change the Federation Authentication Method mapping for the BasicScheme to urn:oasis:names:tc:SAML:2.0:ac:classes:Password instead of urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport for the saml20-sp-partner-profile SAML 2.0 SP Partner Profile (the profile to which my AcmeSP Partner is bound to), I will execute the addSPPartnerProfileAuthnMethod() method: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the addSPPartnerProfileAuthnMethod() command:addSPPartnerProfileAuthnMethod("saml20-sp-partner-profile", "urn:oasis:names:tc:SAML:2.0:ac:classes:Password", "BasicScheme") Exit the WLST environment:exit() After authentication via HTTP Basic Authentication, OIF/IdP would now issue an Assertion similar to (see that the AuthnContextClassRef was changed from PasswordProtectedTransport to Password): <samlp:Response ...>    <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>    <samlp:Status>        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>    </samlp:Status>    <saml:Assertion ...>        <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>        <dsig:Signature>            ...        </dsig:Signature>        <saml:Subject>            <saml:NameID ...>[email protected]</saml:NameID>            <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">                <saml:SubjectConfirmationData .../>            </saml:SubjectConfirmation>        </saml:Subject>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z">            <saml:AuthnContext>                <saml:AuthnContextClassRef>                   urn:oasis:names:tc:SAML:2.0:ac:classes:Password                </saml:AuthnContextClassRef>            </saml:AuthnContext>        </saml:AuthnStatement>    </saml:Assertion></samlp:Response> OAMLDAPPluginAuthnScheme as Authentication Scheme For this test, I will switch the default Authentication Scheme for the SP Partner Profile to OAMLDAPPluginAuthnScheme instead of BasicScheme. I will use the OIF WLST setSPPartnerProfileDefaultScheme() command and specify which scheme to be used as the default for the SP Partner Profile referenced by AcmeSP (which is saml20-sp-partner-profile in this case: getFedPartnerProfile("AcmeSP", "sp") ): Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the setSPPartnerProfileDefaultScheme() command:setSPPartnerProfileDefaultScheme("saml20-sp-partner-profile", "OAMLDAPPluginAuthnScheme") Exit the WLST environment:exit() The user will now be challenged via FORM defined in the OAMLDAPPluginAuthnScheme for AcmeSP. Contrarily to LDAPScheme and BasicScheme, the OAMLDAPPluginAuthnScheme is not mapped by default to any Federation Authentication Methods. As such, OIF/IdP will not be able to find a Federation Authentication Method and will set the method in the SAML Assertion to the OAM Authentication Scheme name. After authentication via FORM, OIF/IdP would issue an Assertion similar to (see the AuthnContextClassRef set to OAMLDAPPluginAuthnScheme): <samlp:Response ...>    <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>    <samlp:Status>        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>    </samlp:Status>    <saml:Assertion ...>        <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>        <dsig:Signature>            ...        </dsig:Signature>        <saml:Subject>            <saml:NameID ...>[email protected]</saml:NameID>            <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">                <saml:SubjectConfirmationData .../>            </saml:SubjectConfirmation>        </saml:Subject>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z">            <saml:AuthnContext>                <saml:AuthnContextClassRef> OAMLDAPPluginAuthnScheme                </saml:AuthnContextClassRef>            </saml:AuthnContext>        </saml:AuthnStatement>    </saml:Assertion></samlp:Response> Mapping OAMLDAPPluginAuthnScheme To add the OAMLDAPPluginAuthnScheme  to the Federation Authentication Method urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport mapping, I will execute the addSPPartnerProfileAuthnMethod() method: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the addSPPartnerProfileAuthnMethod() command:addSPPartnerProfileAuthnMethod("saml20-sp-partner-profile", "urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport", "OAMLDAPPluginAuthnScheme") Exit the WLST environment:exit() After authentication via FORM, OIF/IdP would now issue an Assertion similar to (see that the method was changed from OAMLDAPPluginAuthnScheme to PasswordProtectedTransport): <samlp:Response ...>    <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>    <samlp:Status>        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Success"/>    </samlp:Status>    <saml:Assertion ...>        <saml:Issuer ...>https://idp.com/oam/fed</saml:Issuer>        <dsig:Signature>            ...        </dsig:Signature>        <saml:Subject>            <saml:NameID ...>[email protected]</saml:NameID>            <saml:SubjectConfirmation Method="urn:oasis:names:tc:SAML:2.0:cm:bearer">                <saml:SubjectConfirmationData .../>            </saml:SubjectConfirmation>        </saml:Subject>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthnInstant="2014-03-21T20:53:55Z" SessionIndex="id-6i-Dm0yB-HekG6cejktwcKIFMzYE8Yrmqwfd0azz" SessionNotOnOrAfter="2014-03-21T21:53:55Z">            <saml:AuthnContext>                <saml:AuthnContextClassRef>                   urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport                </saml:AuthnContextClassRef>            </saml:AuthnContext>        </saml:AuthnStatement>    </saml:Assertion></samlp:Response> SAML 1.1 Test Setup In this setup, OIF is acting as an IdP and is integrated with a remote SAML 1.1 SP partner identified by AcmeSP. In this test, I will perform Federation SSO with OIF/IdP configured to: Use LDAPScheme as the Authentication Scheme Use OAMLDAPPluginAuthnScheme as the Authentication Scheme Map OAMLDAPPluginAuthnScheme to  the urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport Federation Authentication Method Use LDAPScheme as the Authentication Scheme Map LDAPScheme to  the urn:oasis:names:tc:SAML:2.0:ac:classes:PasswordProtectedTransport Federation Authentication Method LDAPScheme as Authentication Scheme Using the OOTB settings regarding user authentication in OAM, the user will be challenged via a FORM based login page based on the LDAPScheme. Also the default Federation Authentication Method mappings configuration maps only the urn:oasis:names:tc:SAML:1.0:am:password to LDAPScheme (also marked as the default scheme used for authentication), FAAuthScheme, BasicScheme and BasicFAScheme. After authentication via FORM, OIF/IdP would issue an Assertion similar to: <samlp:Response ...>    <samlp:Status>        <samlp:StatusCode Value="samlp:Success"/>    </samlp:Status>    <saml:Assertion Issuer="https://idp.com/oam/fed" ...>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp/ssov11</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:password">            <saml:Subject>                <saml:NameIdentifier ...>[email protected]</saml:NameIdentifier>                <saml:SubjectConfirmation>                   <saml:ConfirmationMethod>                       urn:oasis:names:tc:SAML:1.0:cm:bearer                   </saml:ConfirmationMethod>                </saml:SubjectConfirmation>            </saml:Subject>        </saml:AuthnStatement>        <dsig:Signature>            ...        </dsig:Signature>    </saml:Assertion></samlp:Response> OAMLDAPPluginAuthnScheme as Authentication Scheme For this test, I will switch the default Authentication Scheme for the SP Partner to OAMLDAPPluginAuthnScheme instead of LDAPScheme. I will use the OIF WLST setSPPartnerDefaultScheme() command and specify which scheme to be used as the default for the SP Partner: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the setSPPartnerDefaultScheme() command:setSPPartnerDefaultScheme("AcmeSP", "OAMLDAPPluginAuthnScheme") Exit the WLST environment:exit() The user will be challenged via FORM defined in the OAMLDAPPluginAuthnScheme for AcmeSP. Contrarily to LDAPScheme, the OAMLDAPPluginAuthnScheme is not mapped by default to any Federation Authentication Methods (in the SP Partner Profile). As such, OIF/IdP will not be able to find a Federation Authentication Method and will set the method in the SAML Assertion to the OAM Authentication Scheme name. After authentication via FORM, OIF/IdP would issue an Assertion similar to (see the AuthenticationMethod set to OAMLDAPPluginAuthnScheme): <samlp:Response ...>    <samlp:Status>        <samlp:StatusCode Value="samlp:Success"/>    </samlp:Status>    <saml:Assertion Issuer="https://idp.com/oam/fed" ...>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp/ssov11</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="OAMLDAPPluginAuthnScheme">            <saml:Subject>                <saml:NameIdentifier ...>[email protected]</saml:NameIdentifier>                <saml:SubjectConfirmation>                   <saml:ConfirmationMethod>                       urn:oasis:names:tc:SAML:1.0:cm:bearer                   </saml:ConfirmationMethod>                </saml:SubjectConfirmation>            </saml:Subject>        </saml:AuthnStatement>        <dsig:Signature>            ...        </dsig:Signature>    </saml:Assertion></samlp:Response> Mapping OAMLDAPPluginAuthnScheme To map the OAMLDAPPluginAuthnScheme  to the Federation Authentication Method urn:oasis:names:tc:SAML:1.0:am:password for this SP Partner only, I will execute the addSPPartnerAuthnMethod() method: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the addSPPartnerAuthnMethod() command:addSPPartnerAuthnMethod("AcmeSP", "urn:oasis:names:tc:SAML:1.0:am:password", "OAMLDAPPluginAuthnScheme") Exit the WLST environment:exit() After authentication via FORM, OIF/IdP would now issue an Assertion similar to (see that the method was changed from OAMLDAPPluginAuthnScheme to password): <samlp:Response ...>    <samlp:Status>        <samlp:StatusCode Value="samlp:Success"/>    </samlp:Status>    <saml:Assertion Issuer="https://idp.com/oam/fed" ...>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp/ssov11</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:password">            <saml:Subject>                <saml:NameIdentifier ...>[email protected]</saml:NameIdentifier>                <saml:SubjectConfirmation>                   <saml:ConfirmationMethod>                       urn:oasis:names:tc:SAML:1.0:cm:bearer                   </saml:ConfirmationMethod>                </saml:SubjectConfirmation>            </saml:Subject>        </saml:AuthnStatement>        <dsig:Signature>            ...        </dsig:Signature>    </saml:Assertion></samlp:Response> LDAPScheme as Authentication Scheme I will now show that by defining a Federation Authentication Mapping at the Partner level, this now ignores all mappings defined at the SP Partner Profile level. For this test, I will switch the default Authentication Scheme for this SP Partner back to LDAPScheme, and the Assertion issued by OIF/IdP will not be able to map this LDAPScheme to a Federation Authentication Method anymore, since A Federation Authentication Method mapping is defined at the SP Partner level and thus the mappings defined at the SP Partner Profile are ignored The LDAPScheme is not listed in the mapping at the Partner level I will use the OIF WLST setSPPartnerDefaultScheme() command and specify which scheme to be used as the default for this SP Partner: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the setSPPartnerDefaultScheme() command:setSPPartnerDefaultScheme("AcmeSP", "LDAPScheme") Exit the WLST environment:exit() After authentication via FORM, OIF/IdP would issue an Assertion similar to (see the AuthenticationMethod set to LDAPScheme): <samlp:Response ...>    <samlp:Status>        <samlp:StatusCode Value="samlp:Success"/>    </samlp:Status>    <saml:Assertion Issuer="https://idp.com/oam/fed" ...>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp/ssov11</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="LDAPScheme">            <saml:Subject>                <saml:NameIdentifier ...>[email protected]</saml:NameIdentifier>                <saml:SubjectConfirmation>                   <saml:ConfirmationMethod>                       urn:oasis:names:tc:SAML:1.0:cm:bearer                   </saml:ConfirmationMethod>                </saml:SubjectConfirmation>            </saml:Subject>        </saml:AuthnStatement>        <dsig:Signature>            ...        </dsig:Signature>    </saml:Assertion></samlp:Response> Mapping LDAPScheme at Partner Level To fix this issue, we will need to add the LDAPScheme  to the Federation Authentication Method urn:oasis:names:tc:SAML:1.0:am:password mapping for this SP Partner only. I will execute the addSPPartnerAuthnMethod() method: Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the addSPPartnerAuthnMethod() command:addSPPartnerAuthnMethod("AcmeSP", "urn:oasis:names:tc:SAML:1.0:am:password", "LDAPScheme") Exit the WLST environment:exit() After authentication via FORM, OIF/IdP would now issue an Assertion similar to (see that the method was changed from LDAPScheme to password): <samlp:Response ...>    <samlp:Status>        <samlp:StatusCode Value="samlp:Success"/>    </samlp:Status>    <saml:Assertion Issuer="https://idp.com/oam/fed" ...>        <saml:Conditions ...>            <saml:AudienceRestriction>                <saml:Audience>https://acme.com/sp/ssov11</saml:Audience>            </saml:AudienceRestriction>        </saml:Conditions>        <saml:AuthnStatement AuthenticationInstant="2014-03-21T20:53:55Z" AuthenticationMethod="urn:oasis:names:tc:SAML:1.0:am:password">            <saml:Subject>                <saml:NameIdentifier ...>[email protected]</saml:NameIdentifier>                <saml:SubjectConfirmation>                   <saml:ConfirmationMethod>                       urn:oasis:names:tc:SAML:1.0:cm:bearer                   </saml:ConfirmationMethod>                </saml:SubjectConfirmation>            </saml:Subject>        </saml:AuthnStatement>        <dsig:Signature>            ...        </dsig:Signature>    </saml:Assertion></samlp:Response> OpenID 2.0 In the OpenID 2.0 flows, the RP must request use of PAPE, in order for OIF/IdP/OP to include PAPE information. For OpenID 2.0, the configuration will involve mapping a list of OpenID 2.0 policies to a list of Authentication Schemes. The WLST command will take a list of policies, delimited by the ',' character, instead of SAML 2.0 or SAML 1.1 where a single Federation Authentication Method had to be specified. Test Setup In this setup, OIF is acting as an IdP/OP and is integrated with a remote OpenID 2.0 SP/RP partner identified by AcmeRP. In this test, I will perform Federation SSO with OIF/IdP configured to: Use LDAPScheme as the Authentication Scheme Map LDAPScheme to  the http://schemas.openid.net/pape/policies/2007/06/phishing-resistant and http://openid-policies/password-protected policies Federation Authentication Methods (the second one is a custom for this use case) LDAPScheme as Authentication Scheme Using the OOTB settings regarding user authentication in OAM, the user will be challenged via a FORM based login page based on the LDAPScheme. No Federation Authentication Method is defined OOTB for OpenID 2.0, so if the IdP/OP issue an SSO response with a PAPE Response element, it will specify the scheme name instead of Federation Authentication Methods After authentication via FORM, OIF/IdP would issue an SSO Response similar to: https://acme.com/openid?refid=id-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=id_res&openid.op_endpoint=https%3A%2F%2Fidp.com%2Fopenid&openid.claimed_id=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.identity=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.return_to=https%3A%2F%2Facme.com%2Fopenid%3Frefid%3Did-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.response_nonce=2014-03-24T19%3A20%3A06Zid-YPa2kTNNFftZkgBb460jxJGblk2g--iNwPpDI7M1&openid.assoc_handle=id-6a5S6zhAKaRwQNUnjTKROREdAGSjWodG1el4xyz3&openid.ns.ax=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.ax.mode=fetch_response&openid.ax.type.attr0=http%3A%2F%2Fsession%2Fcount&openid.ax.value.attr0=1&openid.ax.type.attr1=http%3A%2F%2Fopenid.net%2Fschema%2FnamePerson%2Ffriendly&openid.ax.value.attr1=My+name+is+Bobby+Smith&openid.ax.type.attr2=http%3A%2F%2Fschemas.openid.net%2Fax%2Fapi%2Fuser_id&openid.ax.value.attr2=bob&openid.ax.type.attr3=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.ax.value.attr3=bob%40oracle.com&openid.ax.type.attr4=http%3A%2F%2Fsession%2Fipaddress&openid.ax.value.attr4=10.145.120.253&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.auth_time=2014-03-24T19%3A20%3A05Z&openid.pape.auth_policies=LDAPScheme&openid.signed=op_endpoint%2Cclaimed_id%2Cidentity%2Creturn_to%2Cresponse_nonce%2Cassoc_handle%2Cns.ax%2Cax.mode%2Cax.type.attr0%2Cax.value.attr0%2Cax.type.attr1%2Cax.value.attr1%2Cax.type.attr2%2Cax.value.attr2%2Cax.type.attr3%2Cax.value.attr3%2Cax.type.attr4%2Cax.value.attr4%2Cns.pape%2Cpape.auth_time%2Cpape.auth_policies&openid.sig=mYMgbGYSs22l8e%2FDom9NRPw15u8%3D Mapping LDAPScheme To map the LDAP Scheme to the http://schemas.openid.net/pape/policies/2007/06/phishing-resistant and http://openid-policies/password-protected policies Federation Authentication Methods, I will execute the addSPPartnerAuthnMethod() method (the policies will be comma separated): Enter the WLST environment by executing:$IAM_ORACLE_HOME/common/bin/wlst.sh Connect to the WLS Admin server:connect() Navigate to the Domain Runtime branch:domainRuntime() Execute the addSPPartnerAuthnMethod() command:addSPPartnerAuthnMethod("AcmeRP", "http://schemas.openid.net/pape/policies/2007/06/phishing-resistant,http://openid-policies/password-protected", "LDAPScheme") Exit the WLST environment:exit() After authentication via FORM, OIF/IdP would now issue an Assertion similar to (see that the method was changed from LDAPScheme to the two policies): https://acme.com/openid?refid=id-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.ns=http%3A%2F%2Fspecs.openid.net%2Fauth%2F2.0&openid.mode=id_res&openid.op_endpoint=https%3A%2F%2Fidp.com%2Fopenid&openid.claimed_id=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.identity=https%3A%2F%2Fidp.com%2Fopenid%3Fid%3Did-38iCmmlAVEXPsFjnFVKArfn5RIiF75D5doorhEgqqPM%3D&openid.return_to=https%3A%2F%2Facme.com%2Fopenid%3Frefid%3Did-9PKVXZmRxAeDYcgLqPm36ClzOMA-&openid.response_nonce=2014-03-24T19%3A20%3A06Zid-YPa2kTNNFftZkgBb460jxJGblk2g--iNwPpDI7M1&openid.assoc_handle=id-6a5S6zhAKaRwQNUnjTKROREdAGSjWodG1el4xyz3&openid.ns.ax=http%3A%2F%2Fopenid.net%2Fsrv%2Fax%2F1.0&openid.ax.mode=fetch_response&openid.ax.type.attr0=http%3A%2F%2Fsession%2Fcount&openid.ax.value.attr0=1&openid.ax.type.attr1=http%3A%2F%2Fopenid.net%2Fschema%2FnamePerson%2Ffriendly&openid.ax.value.attr1=My+name+is+Bobby+Smith&openid.ax.type.attr2=http%3A%2F%2Fschemas.openid.net%2Fax%2Fapi%2Fuser_id&openid.ax.value.attr2=bob&openid.ax.type.attr3=http%3A%2F%2Faxschema.org%2Fcontact%2Femail&openid.ax.value.attr3=bob%40oracle.com&openid.ax.type.attr4=http%3A%2F%2Fsession%2Fipaddress&openid.ax.value.attr4=10.145.120.253&openid.ns.pape=http%3A%2F%2Fspecs.openid.net%2Fextensions%2Fpape%2F1.0&openid.pape.auth_time=2014-03-24T19%3A20%3A05Z&openid.pape.auth_policies=http%3A%2F%2Fschemas.openid.net%2Fpape%2Fpolicies%2F2007%2F06%2Fphishing-resistant+http%3A%2F%2Fopenid-policies%2Fpassword-protected&openid.signed=op_endpoint%2Cclaimed_id%2Cidentity%2Creturn_to%2Cresponse_nonce%2Cassoc_handle%2Cns.ax%2Cax.mode%2Cax.type.attr0%2Cax.value.attr0%2Cax.type.attr1%2Cax.value.attr1%2Cax.type.attr2%2Cax.value.attr2%2Cax.type.attr3%2Cax.value.attr3%2Cax.type.attr4%2Cax.value.attr4%2Cns.pape%2Cpape.auth_time%2Cpape.auth_policies&openid.sig=mYMgbGYSs22l8e%2FDom9NRPw15u8%3D In the next article, I will cover how OIF/IdP can be configured so that an SP can request a specific Federation Authentication Method to challenge the user during Federation SSO.Cheers,Damien Carru

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• Strategies for invoking subclass methods on generic objects

  - by Brad Patton

  I've run into this issue in a number of places and have solved it a bunch of different ways but looking for other solutions or opinions on how to address. The scenario is when you have a collection of objects all based off of the same superclass but you want to perform certain actions based only on instances of some of the subclasses. One contrived example of this might be an HTML document made up of elements. You could have a superclass named HTMLELement and subclasses of Headings, Paragraphs, Images, Comments, etc. To invoke a common action across all of the objects you declare a virtual method in the superclass and specific implementations in all of the subclasses. So to render the document you could loop all of the different objects in the document and call a common Render() method on each instance. It's the case where again using the same generic objects in the collection I want to perform different actions for instances of specific subclass (or set of subclasses). For example (an remember this is just an example) when iterating over the collection, elements with external links need to be downloaded (e.g. JS, CSS, images) and some might require additional parsing (JS, CSS). What's the best way to handle those special cases. Some of the strategies I've used or seen used include: Virtual methods in the base class. So in the base class you have a virtual LoadExternalContent() method that does nothing and then override it in the specific subclasses that need to implement it. The benefit being that in the calling code there is no object testing you send the same message to each object and let most of them ignore it. Two downsides that I can think of. First it can make the base class very cluttered with methods that have nothing to do with most of the hierarchy. Second it assumes all of the work can be done in the called method and doesn't handle the case where there might be additional context specific actions in the calling code (i.e. you want to do something in the UI and not the model). Have methods on the class to uniquely identify the objects. This could include methods like ClassName() which return a string with the class name or other return values like enums or booleans (IsImage()). The benefit is that the calling code can use if or switch statements to filter objects to perform class specific actions. The downside is that for every new class you need to implement these methods and can look cluttered. Also performance could be less than some of the other options. Use language features to identify objects. This includes reflection and language operators to identify the objects. For example in C# there is the is operator that returns true if the instance matches the specified class. The benefit is no additional code to implement in your object hierarchy. The only downside seems to be the lack of using something like a switch statement and the fact that your calling code is a little more cluttered. Are there other strategies I am missing? Thoughts on best approaches?

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