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  • IPv6 routing to another interface

    - by Robert
    I'm trying to get an IPv6 enabled router to forward data from one interface to the other and I'm having issues. When following this example (http://www.cisco.com/en/US/tech/tk872/technologies_configuration_example09186a0080ba6106.shtml) I am able to get full connectivity between all 3 routers in my simulator. However when I try to use only 1 router; I can't get connectivity to the other interfacs on the same router. My PC is directly attached to FA 0/1 and it can ping the router's interface. However it can not ping any other interface on the router(which unless I'm missing something it should be able to do). The router on the other hand can ping everything. I thought static routes might help; but the router already has routes for everything. I'm thinking the packet should come in; router looks up the destination in it's ipv6 routing table and then realizes it's for itself, and should respond. I thought maybe it couldn't respond directly; so I tried pinging a device like 2001:0000:0000:1000::2, but i don't get a response. I'm running on IOS 12.4. I'm missing something(hopefully simple), but I just can't see what it is. With only 1 router; how do I enable my PC to talk to the other subnets? Thank you in advance, Robert Topology: R1 FA 0/0: 2001:0000:0000:0000::1/52 FA 0/1: 2001:0000:0000:1000::1/52 FA 1/0: 2001:0000:0000:2000::1/52 Loopback 0: 2001:0000:0000:3000::1/52 PC: 2001:0000:0000:2000::2/52 PC plugs directly into FA 1/0 on the router. --- Configuration --- ipv6 cef ipv6 unicast routing interface Loopback0 no ip address ipv6 address 2001:0000:0000:3000::1/52 ipv6 enable ! interface FastEthernet0/0 no ip address duplex auto speed auto ipv6 address 2001:0000:0000::1/52 ipv6 enable ! interface FastEthernet0/1 no ip address duplex auto speed auto ipv6 address 2001:0000:0000:1000::1/52 ipv6 enable ! interface FastEthernet1/0 no ip address duplex auto speed auto ipv6 address 2001:0000:0000:2000::1/52 ipv6 enable --- end of config --- --- routing table --- IPV6Lab#show ipv6 route IPv6 Routing Table - 10 entries Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP U - Per-user Static route I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 C 2001:0000:0000::/52 [0/0] via ::, FastEthernet0/0 L 2001:0000:0000::1/128 [0/0] via ::, FastEthernet0/0 C 2001:0000:0000:1000::/52 [0/0] via ::, FastEthernet0/1 L 2001:0000:0000:1000::1/128 [0/0] via ::, FastEthernet0/1 C 2001:0000:0000:2000::/52 [0/0] via ::, FastEthernet1/0 L 2001:0000:0000:2000::1/128 [0/0] via ::, FastEthernet1/0 C 2001:0000:0000:3000::/52 [0/0] via ::, Loopback0 L 2001:0000:0000:3000::1/128 [0/0] via ::, Loopback0 L FE80::/10 [0/0] via ::, Null0 L FF00::/8 [0/0] via ::, Null0 --- end of routing table ---

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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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  • Oracle Flashback Technologies - Overview

    - by Sridhar_R-Oracle
    Oracle Flashback Technologies - IntroductionIn his May 29th 2014 blog, my colleague Joe Meeks introduced Oracle Maximum Availability Architecture (MAA) and discussed both planned and unplanned outages. Let’s take a closer look at unplanned outages. These can be caused by physical failures (e.g., server, storage, network, file deletion, physical corruption, site failures) or by logical failures – cases where all components and files are physically available, but data is incorrect or corrupt. These logical failures are usually caused by human errors or application logic errors. This blog series focuses on these logical errors – what causes them and how to address and recover from them using Oracle Database Flashback. In this introductory blog post, I’ll provide an overview of the Oracle Database Flashback technologies and will discuss the features in detail in future blog posts. Let’s get started. We are all human beings (unless a machine is reading this), and making mistakes is a part of what we do…often what we do best!  We “fat finger”, we spill drinks on keyboards, unplug the wrong cables, etc.  In addition, many of us, in our lives as DBAs or developers, must have observed, caused, or corrected one or more of the following unpleasant events: Accidentally updated a table with wrong values !! Performed a batch update that went wrong - due to logical errors in the code !! Dropped a table !! How do DBAs typically recover from these types of errors? First, data needs to be restored and recovered to the point-in-time when the error occurred (incomplete or point-in-time recovery).  Moreover, depending on the type of fault, it’s possible that some services – or even the entire database – would have to be taken down during the recovery process.Apart from error conditions, there are other questions that need to be addressed as part of the investigation. For example, what did the data look like in the morning, prior to the error? What were the various changes to the row(s) between two timestamps? Who performed the transaction and how can it be reversed?  Oracle Database includes built-in Flashback technologies, with features that address these challenges and questions, and enable you to perform faster, easier, and convenient recovery from logical corruptions. HistoryFlashback Query, the first Flashback Technology, was introduced in Oracle 9i. It provides a simple, powerful and completely non-disruptive mechanism for data verification and recovery from logical errors, and enables users to view the state of data at a previous point in time.Flashback Technologies were further enhanced in Oracle 10g, to provide fast, easy recovery at the database, table, row, and even at a transaction level.Oracle Database 11g introduced an innovative method to manage and query long-term historical data with Flashback Data Archive. The 11g release also introduced Flashback Transaction, which provides an easy, one-step operation to back out a transaction. Oracle Database versions 11.2.0.2 and beyond further enhanced the performance of these features. Note that all the features listed here work without requiring any kind of restore operation.In addition, Flashback features are fully supported with the new multi-tenant capabilities introduced with Oracle Database 12c, Flashback Features Oracle Flashback Database enables point-in-time-recovery of the entire database without requiring a traditional restore and recovery operation. It rewinds the entire database to a specified point in time in the past by undoing all the changes that were made since that time.Oracle Flashback Table enables an entire table or a set of tables to be recovered to a point in time in the past.Oracle Flashback Drop enables accidentally dropped tables and all dependent objects to be restored.Oracle Flashback Query enables data to be viewed at a point-in-time in the past. This feature can be used to view and reconstruct data that was lost due to unintentional change(s) or deletion(s). This feature can also be used to build self-service error correction into applications, empowering end-users to undo and correct their errors.Oracle Flashback Version Query offers the ability to query the historical changes to data between two points in time or system change numbers (SCN) Oracle Flashback Transaction Query enables changes to be examined at the transaction level. This capability can be used to diagnose problems, perform analysis, audit transactions, and even revert the transaction by undoing SQLOracle Flashback Transaction is a procedure used to back-out a transaction and its dependent transactions.Flashback technologies eliminate the need for a traditional restore and recovery process to fix logical corruptions or make enquiries. Using these technologies, you can recover from the error in the same amount of time it took to generate the error. All the Flashback features can be accessed either via SQL command line (or) via Enterprise Manager.  Most of the Flashback technologies depend on the available UNDO to retrieve older data. The following table describes the various Flashback technologies: their purpose, dependencies and situations where each individual technology can be used.   Example Syntax Error investigation related:The purpose is to investigate what went wrong and what the values were at certain points in timeFlashback Queries  ( select .. as of SCN | Timestamp )   - Helps to see the value of a row/set of rows at a point in timeFlashback Version Queries  ( select .. versions between SCN | Timestamp and SCN | Timestamp)  - Helps determine how the value evolved between certain SCNs or between timestamps Flashback Transaction Queries (select .. XID=)   - Helps to understand how the transaction caused the changes.Error correction related:The purpose is to fix the error and correct the problems,Flashback Table  (flashback table .. to SCN | Timestamp)  - To rewind the table to a particular timestamp or SCN to reverse unwanted updates Flashback Drop (flashback table ..  to before drop )  - To undrop or undelete a table Flashback Database (flashback database to SCN  | Restore Point )  - This is the rewind button for Oracle databases. You can revert the entire database to a particular point in time. It is a fast way to perform a PITR (point-in-time recovery). Flashback Transaction (DBMS_FLASHBACK.TRANSACTION_BACKOUT(XID..))  - To reverse a transaction and its related transactions Advanced use cases Flashback technology is integrated into Oracle Recovery Manager (RMAN) and Oracle Data Guard. So, apart from the basic use cases mentioned above, the following use cases are addressed using Oracle Flashback. Block Media recovery by RMAN - to perform block level recovery Snapshot Standby - where the standby is temporarily converted to a read/write environment for testing, backup, or migration purposes Re-instate old primary in a Data Guard environment – this avoids the need to restore an old backup and perform a recovery to make it a new standby. Guaranteed Restore Points - to bring back the entire database to an older point-in-time in a guaranteed way. and so on..I hope this introductory overview helps you understand how Flashback features can be used to investigate and recover from logical errors.  As mentioned earlier, I will take a deeper-dive into to some of the critical Flashback features in my upcoming blogs and address common use cases.

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  • Where should I start with debugging my exchange server?

    - by joadha
    I'm (foolishly?) attempting to install Exchange on top of Windows Server 2008 (64-bit) over Virtual Box running on Mac OSX Lion. Everything went smoothly until I got to the "Readiness Checks" tab. Readiness failed spectacularly on Hub Transport Role and Mailbox Role prereqs. Before I go too far down the rabbit hole in attempting to remedy this, I was hoping I could get some input on where to start in all of this. I already set up the following Active Directory roles, but it didn't seem to help: Active Directory Domain Services Active Directory Lightweight Directory Services I also enabled an Application Server role. Those three are the only roles I've set up-- I cannot locate within Server Manager the Organization Manager role or any of the other roles referenced in the list of borkedness below. Is this a typical experience in Exchange installation? Is there a tutorial created by somebody outside of Microsoft? Here's the output from Readiness Checks: Summary: 5 item(s). 2 succeeded, 3 failed. Elapsed time: 00:00:53 Configuring Prerequisites Completed Elapsed Time: 00:00:00 Languages Prerequisites Completed Elapsed Time: 00:00:09 Hub Transport Role Prerequisites Failed Error: Active Directory does not exist or cannot be contacted. Click here for help... http://go.microsoft.com/fwlink/? linkid=30939&l=en&v=ExBPA.14&id=51e5500d-8b18-4eee-bb8e-925d063b60a1 Error: You must be a member of the 'Organization Management' role group or 'Enterprise Admins' group to continue. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=1d750594-9222-44d7-8f80-45e522e889e6 Error: Setup encountered a problem while validating the state of Active Directory: Could not find information about the local domain. Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Error: You must be logged on as an Exchange organization administrator to install or upgrade the first Hub Transport server role in the topology. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=e58f51fd-2c66-4a4b-914a-628dccf9a09f Error: The 'IIS 6 Metabase Compatibility' component is not installed. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=0a71c4f6-68de-40f7-94cf-74b73cbda37b Error: The 'IIS 7 Basic Authentication' component required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 Windows Authentication' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 .NET Extensibility' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=5f29a861-f472-4f11-a23a-04155373f5ed Error: This computer is not part of a Windows domain. Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Error: The user is not logged on to a Windows domain Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Warning: This computer requires the Microsoft Office 2010 Filter Packs. Please install the software from http://go.microsoft.com/fwlink/?LinkID=191548 Warning: The 'IIS 6 Management Console' component is recommended as it allows for the administration of all server roles. Install the component via Server Manager. Warning: Setup cannot verify that the 'Host' (A) record for this computer exists within the DNS database on server 10.1.10.1. Elapsed Time: 00:00:15 Client Access Role Prerequisites Failed Error: Active Directory does not exist or cannot be contacted. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=51e5500d-8b18-4eee-bb8e-925d063b60a1 Error: Unable to read data from the Metabase. Ensure that Microsoft Internet Information Services is installed. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=a4a4d339-4009-4fb7-b842-ca2ba79f13f0 Error: The World Wide Web (W3SVC) service is either disabled or not installed on this computer. You must exit Setup, install the required component, then restart the Setup process. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=9eeaa77f-4d46-4d9a-9c36-f262a075392b Error: You must be a member of the 'Organization Management' role group or 'Enterprise Admins' group to continue. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=1d750594-9222-44d7-8f80-45e522e889e6 Error: Setup encountered a problem while validating the state of Active Directory: Could not find information about the local domain. Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Error: You must be logged on as an Exchange organization administrator to install or upgrade the first Client Access server role in the topology. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=e58f51fd-2c66-4a4b-914a-628dccf9a09f Error: The 'IIS 6 Metabase Compatibility' component is not installed. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=0a71c4f6-68de-40f7-94cf-74b73cbda37b Error: The 'IIS 6 Management Console' component is not installed. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=0a71c4f6-68de-40f7-94cf-74b73cbda37b Error: The 'IIS 7 Dynamic Content Compression' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/? linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 Static Content Compression' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 Basic Authentication' component required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 Windows Authentication' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 Digest Authentication' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 .NET Extensibility' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=5f29a861-f472-4f11-a23a-04155373f5ed Error: This computer is not part of a Windows domain. Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Error: The user is not logged on to a Windows domain Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Warning: Setup cannot verify that the 'Host' (A) record for this computer exists within the DNS database on server 10.1.10.1. Elapsed Time: 00:00:14 Mailbox Role Prerequisites Failed Error: Active Directory does not exist or cannot be contacted. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=51e5500d-8b18-4eee-bb8e-925d063b60a1 Error: Unable to read data from the Metabase. Ensure that Microsoft Internet Information Services is installed. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=a4a4d339-4009-4fb7-b842-ca2ba79f13f0 Error: The World Wide Web (W3SVC) service is either disabled or not installed on this computer. You must exit Setup, install the required component, then restart the Setup process. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=9eeaa77f-4d46-4d9a-9c36-f262a075392b Error: You must be a member of the 'Organization Management' role group or 'Enterprise Admins' group to continue. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=1d750594-9222-44d7-8f80-45e522e889e6 Error: Setup encountered a problem while validating the state of Active Directory: Could not find information about the local domain. Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Error: You must be logged on as an Exchange organization administrator to install or upgrade the first Mailbox server role in the topology. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=e58f51fd-2c66-4a4b-914a-628dccf9a09f Error: The 'IIS 6 Metabase Compatibility' component is not installed. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=0a71c4f6-68de-40f7-94cf-74b73cbda37b Error: The 'IIS 6 Management Console' component is not installed. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=0a71c4f6-68de-40f7-94cf-74b73cbda37b Error: The 'IIS 7 Basic Authentication' component required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 Windows Authentication' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=41a25c5e-0d39-4e55-a1f0-7be885982236 Error: The 'IIS 7 .NET Extensibility' component is required. Install the component via Server Manager. Click here for help... http://go.microsoft.com/fwlink/?linkid=30939&l=en&v=ExBPA.14&id=5f29a861-f472-4f11-a23a-04155373f5ed Error: This computer is not part of a Windows domain. Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Error: The user is not logged on to a Windows domain Click here for help... http://technet.microsoft.com/en-US/library/ms.exch.err.default(EXCHG.141).aspx?v=14.1.218.11&e=ms.exch.err.Ex28883C&l=0&cl=cp Warning: This computer requires the Microsoft Office 2010 Filter Packs. Please install the software from http://go.microsoft.com/fwlink/?LinkID=191548 Warning: Setup cannot verify that the 'Host' (A) record for this computer exists within the DNS database on server 10.1.10.1. Elapsed Time: 00:00:14

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  • Rotating a NetBeans Visual Library Widget

    - by Geertjan
    Trying to create a widget which, when clicked, rotates slightly further on each subsequent click: Above, the bird where the mouse is visible has been clicked a few times and so has rotated a bit further on each click. The code isn't quite right yet and I'm hoping someone will take this code, try it out, and help with a nice solution! public class BirdScene extends Scene {     public BirdScene() {         addChild(new LayerWidget(this));         getActions().addAction(ActionFactory.createAcceptAction(new AcceptProvider() {             public ConnectorState isAcceptable(Widget widget, Point point, Transferable transferable) {                 Image dragImage = getImageFromTransferable(transferable);                 if (dragImage != null) {                     JComponent view = getView();                     Graphics2D g2 = (Graphics2D) view.getGraphics();                     Rectangle visRect = view.getVisibleRect();                     view.paintImmediately(visRect.x, visRect.y, visRect.width, visRect.height);                     g2.drawImage(dragImage,                             AffineTransform.getTranslateInstance(point.getLocation().getX(),                             point.getLocation().getY()),                             null);                     return ConnectorState.ACCEPT;                 } else {                     return ConnectorState.REJECT;                 }             }             public void accept(Widget widget, final Point point, Transferable transferable) {                 addChild(new BirdWidget(getScene(), getImageFromTransferable(transferable), point));             }         }));     }     private Image getImageFromTransferable(Transferable transferable) {         Object o = null;         try {             o = transferable.getTransferData(DataFlavor.imageFlavor);         } catch (IOException ex) {         } catch (UnsupportedFlavorException ex) {         }         return o instanceof Image ? (Image) o : null;     }     private class BirdWidget extends IconNodeWidget {         private int theta = 0;         public BirdWidget(Scene scene, Image imageFromTransferable, Point point) {             super(scene);             setImage(imageFromTransferable);             setPreferredLocation(point);             setCheckClipping(true);             getActions().addAction(ActionFactory.createMoveAction());             getActions().addAction(ActionFactory.createSelectAction(new SelectProvider() {                 public boolean isAimingAllowed(Widget widget, Point localLocation, boolean invertSelection) {                     return true;                 }                 public boolean isSelectionAllowed(Widget widget, Point localLocation, boolean invertSelection) {                     return true;                 }                 public void select(final Widget widget, Point localLocation, boolean invertSelection) {                     theta = (theta + 100) % 360;                     repaint();                     getScene().validate();                 }             }));         }         @Override         public void paintWidget() {             final Image image = getImageWidget().getImage();             Graphics2D g = getGraphics();             g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);             Rectangle bounds = getClientArea();             AffineTransform newXform = g.getTransform();             int xRot = image.getWidth(null) / 2;             int yRot = image.getWidth(null) / 2;             newXform.rotate(theta * Math.PI / 180, xRot, yRot);             g.setTransform(newXform);             g.drawImage(image, bounds.x, bounds.y, null);         }     } } The problem relates to refreshing the scene after the rotation. But it would help if someone would just take the code above, add it to their own application, try it out, see the problem for yourself, and develop it a bit further!

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  • Run a JasperServer reprt via PHP and pass over the querystring.

    - by Ronedog
    I'm using Web Services to run some reports created in iReport on JasperServer. Inside the .jrxml file I can see the xml that holds the SQL for the report. Is it possible to pass this querystring over to JasperServer via Web Services, instead of hard coding the definition inside the .jrxml file. This is the string I would build in PHP, then pass over to JasperServer to be used in the execution of the report. <queryString> <![CDATA[SELECT * FROM table WHERE j=2]]> </queryString> Basically, I'm trying to find a way to dynamically create the SQL in PHP, then pass the SQL over to Jasper to run the report...is it even possible? Thanks.

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  • How can I tell if a user came to a page via a Google Adwords PPC campaign?

    - by Mike Crittenden
    I have a form with a hidden "Came from Adwords" field that will be marked true (via javascript) if the user came from a PPC campaign and will stay false if not. That way, when the user submits the form, we will have each submission stored with info about whether that submission came from adwords or not, all without the user knowing. How can I fetch this info? I know that Google sets a cookie called Conversion whenever you click a PPC link to a page, but the cookie's content is just random alphanumeric characters. Is there something in the Analytics/Adwords API that will let me test for this? Do I have to resort to adding ?ref=adwords or something onto the PPC URLs so that I can test that way?

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  • How to query the like count of a facebook object such as a album or photo via fql?

    - by hip10
    Hi, Here is a tricky question, how do you get the like count of a facebook object such as an album or a photo? I know that facebook has a fql table called link_stat that allow you to get the like count for an external url, but it does not seem to work if the object is within facebook. If you access the likes via the opengraph api on a particular object, it will only return a maximum of 4 users that like the object, even though there maybe a few thousand users that like it. Any clues?

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  • Can I pass data via JQUERY to ASP.NET MVC controller action and have a view rendered in new browser

    - by Simon Lomax
    Hi, Can anyone advise if its possible to pass data via JQUERY to an ASP.NET MVC controller action and have a view rendered in new browser tab based on the model data passed to the action method. My scenario is that I have a Jqgrid populated with product info on a page. The user would tick the items in the grid that they would like a label produced for. After they've made their slection they would click a button and I would like (if possible) to render a view of that contains a label for each selected item and have the view render in a new browser tab. All the code to allow the selections and post the relevant data back to the action method is all working fine and I know its easy to use the Jquery $(selector).load() command to populate an element on the current page with the HTML returned from the action. But is it possible to populate an element on a page in a new browser tab. If it is how would I go about it? Hope this make sense.

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  • Is there an extensible SQL like query language that is safe for exposing via a public API?

    - by Lokkju
    I want to expose some spatial (and a few non-spatial) datasets via a public API. The backend store will either be PostgreSQL/PostGIS, sqlite/spatialite, or CouchDB/GeoCouch. My goal is to find a some, preferably standard, way to allow people to make complex spatial queries against the data. I would like it to be a simple GET based request. The idea is to allow safe SQL type queries, without allowing unsafe ones. I would rather modify something that is off the shelf than doing the entire thing myself. I specifically want to support requesting specific fields from a table; joining results; and spatial functions that are already implemented by the underlying datastore. Ideas anyone?

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  • Can Hibernate automatically uppercase a column on read/insert via configuration?

    - by T Reddy
    We have some columns with data that must always be in uppercase to ensure uniqueness. I was wondering if hibernate can force all such columns to uppercase via some configuration file change? We actually use a custom UserType for encrypting/decrypting column data for some other table, but I figured that would be overkill just to uppercase everything... Alternatively, I was thinking about modifying the models such that all getters/setters will uppercase any string coming and going. The worst(?) case scenario is to modify the Oracle column constraint to ignore case while checking uniqueness. Any thoughts?

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  • ASP.NET MVC: Is it "wrong" to use HTTP 500 via an AJAX request to return invalid form content?

    - by Daniel Schaffer
    Here's the situation: I've got two partial views. One has a form. What needs to happen is when the form is posted via an AJAX request, if the operation succeeds, the area with the second partial is repopulated with the content. However, if the posted data was invalid, the original partial is repopulated with an error message. I'm using jQuery and the ajaxForm plugin to handle the form posts and responses. Would it be "wrong"/bad coding/wtf-worthy to conditionally use $.html() to replace the content in one area when it's a 200, and a different area if it's a 500? To me, this idea smells, but I'm not sure how else to accomplish the goal.

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  • Advanced Java book in the lines of CLR via c# or C# in Depth?

    - by devoured elysium
    I want to learn about how things work in depth in Java. Coming from a c# background, there were a couple of very good books that go really deep in c# (C# in depth, CLR via c#, just to name the most popular). Is there anything like that in Java? I searched it up on amazon but nothing seemed to go that deep in Java as the two above go in c#. I don't want to know more about specific classes, or how to use this library or that other library, I want to learn how the objects are created on memory, how they get created on the stack, heap, etc. A more fundamental knowledge, let's say. I've read some chapters of Effective Java and The Java Programming Language but they don't seem to go so deep as I'd want them to go. Maybe there are other people that know both c# and Java that have read any of the referred books and know any that might be useful? Thanks

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  • Why does this XML validation via XSD fail in libxml2 (but succeed in xmllint) and how do I fix it?

    - by mtree
    If I run this XML validation via xmllint: xmllint --noout --schema schema.xsd test.xml I get this success message: .../test.xml validates However if I run the same validation via libxml2's C API: int result = xmlSchemaValidateDoc(...) I get a return value of 1845 and this failure message: Element '{http://example.com/XMLSchema/1.0}foo': No matching global declaration available for the validation root. Which I can make absolutely no sense of. :( schema.xsd: <?xml version="1.0" encoding="utf-8" ?> <!DOCTYPE xs:schema PUBLIC "-//W3C//DTD XMLSCHEMA 200102//EN" "XMLSchema.dtd" > <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://example.com/XMLSchema/1.0" targetNamespace="http://example.com/XMLSchema/1.0" elementFormDefault="qualified" attributeFormDefault="unqualified"> <xs:element name="foo"> </xs:element> </xs:schema> test.xml: <?xml version="1.0" encoding="UTF-8"?> <foo xmlns="http://example.com/XMLSchema/1.0"> </foo> main.c: #include <stdio.h> #include <sys/stat.h> #include <sys/types.h> #include <string.h> #include <libxml/parser.h> #include <libxml/valid.h> #include <libxml/xmlschemas.h> u_int32_t get_file_size(const char *file_name) { struct stat buf; if ( stat(file_name, &buf) != 0 ) return(0); return (unsigned int)buf.st_size; } void handleValidationError(void *ctx, const char *format, ...) { char *errMsg; va_list args; va_start(args, format); vasprintf(&errMsg, format, args); va_end(args); fprintf(stderr, "Validation Error: %s", errMsg); free(errMsg); } int main (int argc, const char * argv[]) { const char *xsdPath = argv[1]; const char *xmlPath = argv[2]; printf("\n"); printf("XSD File: %s\n", xsdPath); printf("XML File: %s\n", xmlPath); int xmlLength = get_file_size(xmlPath); char *xmlSource = (char *)malloc(sizeof(char) * xmlLength); FILE *p = fopen(xmlPath, "r"); char c; unsigned int i = 0; while ((c = fgetc(p)) != EOF) { xmlSource[i++] = c; } printf("\n"); printf("XML Source:\n\n%s\n", xmlSource); fclose(p); printf("\n"); int result = 42; xmlSchemaParserCtxtPtr parserCtxt = NULL; xmlSchemaPtr schema = NULL; xmlSchemaValidCtxtPtr validCtxt = NULL; xmlDocPtr xmlDocumentPointer = xmlParseMemory(xmlSource, xmlLength); parserCtxt = xmlSchemaNewParserCtxt(xsdPath); if (parserCtxt == NULL) { fprintf(stderr, "Could not create XSD schema parsing context.\n"); goto leave; } schema = xmlSchemaParse(parserCtxt); if (schema == NULL) { fprintf(stderr, "Could not parse XSD schema.\n"); goto leave; } validCtxt = xmlSchemaNewValidCtxt(schema); if (!validCtxt) { fprintf(stderr, "Could not create XSD schema validation context.\n"); goto leave; } xmlSetStructuredErrorFunc(NULL, NULL); xmlSetGenericErrorFunc(NULL, handleValidationError); xmlThrDefSetStructuredErrorFunc(NULL, NULL); xmlThrDefSetGenericErrorFunc(NULL, handleValidationError); result = xmlSchemaValidateDoc(validCtxt, xmlDocumentPointer); leave: if (parserCtxt) { xmlSchemaFreeParserCtxt(parserCtxt); } if (schema) { xmlSchemaFree(schema); } if (validCtxt) { xmlSchemaFreeValidCtxt(validCtxt); } printf("\n"); printf("Validation successful: %s (result: %d)\n", (result == 0) ? "YES" : "NO", result); return 0; } console output: XSD File: /Users/dephiniteloop/Desktop/xml_validate/schema.xsd XML File: /Users/dephiniteloop/Desktop/xml_validate/test.gkml XML Source: <?xml version="1.0" encoding="UTF-8"?> <foo xmlns="http://example.com/XMLSchema/1.0"> </foo> Validation Error: Element '{http://example.com/XMLSchema/1.0}foo': No matching global declaration available for the validation root. Validation successful: NO (result: 1845) In case it matters: I'm on OSX 10.6.7 with its default libxml2.dylib (/Developer/SDKs/MacOSX10.6.sdk/usr/lib/libxml2.2.7.3.dylib)

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  • Any way to do slanted/diagonal mouseovers via css/javascript?

    - by cksubs
    Hi, I have a box built via html borders. I want to connect the bottom left corner to the top right corner with a diagonal line. Either with html/css or by using a background image, doesn't matter. I'll figure that part out later. ------ - /- - / - - / - -/---- Here's the tricky part: I want a different thing to happen depending on which side of the line the mouse is hovering over. I'll do something like make some text visible or change the background color. Is that possible in web programing? I've thought of doing a "Riemann sum" type calculation with a bunch of invisible divs. Any easier way? Thanks!

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  • What design considerations should one take to receive text and multiple attachments via web?

    - by ramesh.nagul
    I am developing a web application to accept a bunch of text and attachments (1 or more) via email, web and other methods. I am planning to build a single interface, mostly a web service to accept this content. What design considerations should I make? I am building the app using ASP.NET MVC 2. Should the attachments be saved to disk or in the database? Should the unified single interface be a web service? Pros and cons to using web services to upload files

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  • Linux periodically "losing" ability to connect to server via SSH?

    - by gct
    I know this isn't exactly a programming question, but it popped up in my use of git for programming projects at least. I've got a web server that I use to host my git repos on, but my ubuntu box seems to "lose" the ability to connect to it via SSH. I'll get a "connection refused" error when I try to ssh or use git. Rebooting my local machine will fix the problem, but only temporarily. I can still connect to the web interface just fine, and the problem manifests with other servers as well. I've been working around it by pulling my changes over to my laptop and pushing from there, but that's sub-optimal as you can imagine. Has anyone seen something like this? I'd be tempted to say it's some kind of IP caching problem, but I can't connect even using the IP address of the server directly... Running Ubuntu 9.04

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  • How to add sort function for the table via ajax in ASP.NET MVC?What is the best practice.

    - by Eric Wang
    How to add sort function for the table via ajax in ASP.NET MVC?What is the best practice. If not use Ajax, it maybe much easier, just return View, but if use AJAX, what data structure should return?I just use Json to return the data, but i found each JSON data model return to the client browser, the JS have to use different code to parse it, remove the originally table rows, add the new data rows(because the column is different) etc. It make me crazy, is there any better way to do that? Thank you for any advice.

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  • Is it actually possible to connect to ActiveMQ via XMPP and query/browse queues using "AciveMQ.Agen

    - by Oleg Kiorsak
    I tried what I think are 4 most popular XMPP (aka "Jabber") clients (Spark, Pidgin, Psi, Pandion) to connect to ActiveMQ instance (Apache ActiveMQ ver. 5.3.0) on XMMP connector with an idea to use the "AciveMQ.Agent chatroom" for querying queues/etc and no success at all Some of them fail with 'Unknown error', some don't fail but kind of "hang"... interestingly, some communication does indeed reach the ActiveMQ side, because when I close a client it spits an exception "could not close" or something to that effect... and if I try "register new user" option (present on most clients" the ActiveMQ also spits some most cryptic warning message But I was never able to get to the point when I could see or specify "ActiveMQ.Agent" as chatroom and issue any commands... Before I waste any more time on this curious feature, I would like to hear whether anyone had any success with it? Thank you! PS: BTW, the book "ActiveMQ in Action book" http://www.manning.com/snyder/ shows that it is apparently works and is very easy using some Mac client (AdiumX), but I wanted it on a Windows PC ;)

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  • Will the URL /nosuchpage get routed via my ASP.NET MVC application?

    - by Gary McGill
    [I'm trying to figure out the reason why I'm having another problem, and this question is part of the puzzle.] I have an MVC 2 website that has routing set up so that URLs such as /Customer/23/Order/47 get handled by various controllers. I do not have a rule that would match, for example, /nosuchpage and in my Cassini environment a request for that URL will trigger my Application_Error code, which lets me log the error and show a friendly response. However, when I deployed this website on IIS7 using integrated mode, my Application_Error is not triggered, and IIS shows its own 404 message. No matter what I've tried, I can't get Application_Error to fire. Now I'm thinking: is the reason it doesn't fire because the request is not getting routed via my application? Either because I didn't explicitly set up a catch-all route, or because the file-extension fools it into thinking it should use the "static file handler" (whatever that is)? Should I expect my Application_Error to be invoked?

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  • Any way using JavaScript API via iOS? and problem with FQL queries responses.

    - by Assaf b
    Hi, I'm developing an iPhone application with FB connect, the JavaScript API includes really powerful methods like wait.on for combining requests... Any way using those API methods via iOS and Xcode? about the FQL responses, I'm using both: request:didReceiveResponse: AND request:didLoad: methods. all the FQL queries I send provoke didReceiveResponse but not all of them provoke the second one (didLoad). @"SELECT uid,eid FROM event_member WHERE uid in (select uid2 from friend where uid1=%d limit 100)", userID when the limit is 1-2 it provokes them all, when it grows too 100 (friends to fetch) it provokes only the first.. does anyone know this problem? Thanks!

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  • How can I launch a system command via Javascript in Google Chrome?

    - by kvsn
    I want to execute a local program on my computer via Javascript in Chrome. In Firefox, it can be done as follows (after setting 'signed.applets.codebase_principal_support' to true in about:config): function run_cmd(cmd, args) { netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect"); var file = Components.classes["@mozilla.org/file/local;1"] .createInstance(Components.interfaces.nsILocalFile); file.initWithPath(cmd); var process = Components.classes["@mozilla.org/process/util;1"] .createInstance(Components.interfaces.nsIProcess); process.init(file); process.run(false, args, args.length); } What's the equivalent code for Chrome?

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  • How can you determine if Control.Visible is set via property or if the value is inherited

    - by JDMX
    I need to find a way to determine if the Visible property of a control is set via a property change or if is inheriting it value from its parent. Using the Reflector, I find that the functions this.GetVisibleCore() and this.GetState() are both internal methods so I cannot call them. The widgets themselves are created dynamically so I do not want to attach a method to the VisibleChanged event just after the creation of each widget so can try to monitor this property. If I have to, I guess I will but I am looking for something jsut a bit more elegant.

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  • Is it dangerous to store user-enterable text into a hidden form via javascript?

    - by KallDrexx
    In my asp.net MVC application I am using in place editors to allow users to edit fields without having a standard form view. Unfortunately, since I am using Linq to Sql combined with my data mapping layer I cannot just update one field at a time and instead need to send all fields over at once. So the solution I came up with was to store all my model fields into hidden fields, and provide span tags that contain the visible data (these span tags become editable due to my jquery plugin). When a user triggers a save of their edits of a field, jquery then takes their value and places it in the hidden form, and sends the whole form to the server to commit via ajax. When the data goes into the hidden field originally (page load) and into the span tags the data is properly encoded, but upon the user changing the data in the contenteditable span field, I just run $("#hiddenfield").val($("#spanfield").html(); Am I opening any holes this method? Obviously the server also properly encodes stuff prior to database entry.

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