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• How to map string keys to unique integer IDs?

  - by Marek

  I have some data that comes regularily as a dump from a data souce with a string natural key that is long (up to 60 characters) and not relevant to the end user. I am using this key in a url. This makes urls too long and user unfriendly. I would like to transform the string keys into integers with the following requirements: The source dataset will change over time. The ID should be: non negative integer unique and constant even if the set of input keys changes preferrably reversible back to key (not a strong requirement) The database is rebuilt from scratch every time so I can not remember the already assigned IDs and match the new data set to existing IDs and generate sequential IDs for the added keys. There are currently around 30000 distinct keys and the set is constantly growing. How to implement a function that will map string keys to integer IDs? What I have thought about: 1. Built-in string.GetHashCode: ID(key) = Math.Abs(key.GetHashCode()) is not guaranteed to be unique (not reversible) 1.1 "Re-hashing" the built-in GetHashCode until a unique ID is generated to prevent collisions. existing IDs may change if something colliding is added to the beginning of the input data set 2. a perfect hashing function I am not sure if this can generate constant IDs if the set of inputs changes (not reversible) 3. translate to base 36/64/?? does not shorten the long keys enough What are the other options?

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• VB .NET Passing a Structure containing an array of String and an array of Integer into a C++ DLL

  - by DanJunior

  Hi everyone, I'm having problems with marshalling in VB .NET to C++, here's the code : In the C++ DLL : struct APP_PARAM { int numData; LPCSTR *text; int *values; }; int App::StartApp(APP_PARAM params) { for (int i = 0; i < numLines; i++) { OutputDebugString(params.text[i]); } } In VB .NET : <StructLayoutAttribute(LayoutKind.Sequential)> _ Public Structure APP_PARAM Public numData As Integer Public text As System.IntPtr Public values As System.IntPtr End Structure Declare Function StartApp Lib "AppSupport.dll" (ByVal params As APP_PARAM) As Integer Sub Main() Dim params As APP_PARAM params.numData = 3 Dim text As String() = {"A", "B", "C"} Dim textHandle As GCHandle = GCHandle.Alloc(text) params.text = GCHandle.ToIntPtr(textHandle) Dim values As Integer() = {10, 20, 30} Dim valuesHandle As GCHandle = GCHandle.Alloc(values) params.values = GCHandle.ToIntPtr(heightHandle) StartApp(params) textHandle.Free() valuesHandle.Free() End Sub I checked the C++ side, the output from the OutputDebugString is garbage, the text array contains random characters. What is the correct way to do this?? Thanks a lot...

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• Is there any well-known paradigm for iterating enum values?

  - by SadSido

  I have some C++ code, in which the following enum is declared: enum Some { Some_Alpha = 0, Some_Beta, Some_Gamma, Some_Total }; int array[Some_Total]; The values of Alpha, Beta and Gamma are sequential, and I gladly use the following cycle to iterate through them: for ( int someNo = (int)Some_Alpha; someNo < (int)Some_Total; ++someNo ) {} This cycle is ok, until I decide to change the order of the declarations in the enum, say, making Beta the first value and Alpha - the second one. That invalidates the cycle header, because now I have to iterate from Beta to Total. So, what are the best practices of iterating through enum? I want to iterate through all the values without changing the cycle headers every time. I can think of one solution: enum Some { Some_Start = -1, Some_Alpha, ... Some_Total }; int array[Some_Total]; and iterate from (Start + 1) to Total, but it seems ugly and I have never seen someone doing it in the code. Is there any well-known paradigm for iterating through the enum, or I just have to fix the order of the enum values? (let's pretend, I really have some awesome reasons for changing the order of the enum values)...

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• In sync query calls, one query causing other query to run slower. Why?

  - by Irchi

  Sorry for the long question, but I think this is an interesting situation and I couldn't find any explanations for it: I was involved in optimization of an application that performed a large number of sequential SELECT and INSERT statements on a single dedicated SQL Server database. The process needs to INSERT a large number of records into a table, but for each of them there should be some value mappings, which performed using SELECT statements on another table in the same database. For a specific execution, it took 90 minutes to run. I used a profiler (JProfiler - the application is Java-based) to determine how much time does each part of the application take. It yields that 60% of the time was spent on INSERT method calls, and almost 20% on SELECT calls (the rest distributed in other parts). After some trials, I came to this situation: I commented out the INSERT query that took 60% of the time. I was expecting for the total run time to be around 35 minutes, as I have removed 60% of the 90 minutes. But the whole process took the same 90 minutes (doing only SELECTs and nothing else), but each SELECT took longer this time! Everything was running sync, there were no async calls. And there was only one single thread of execution. SELECT and INSERT queries are very simple, and don't have anything special, and they are on different tables, but on the same DB. I tested with both the DB on the application machine, and on a remote network machine. I can't think of any explanation for this, as the Profiler (Application profiler, not SQL Profiler) reported the changes in the method call times, and by removing INSERT statements SELECT statements took longer to run. Can anyone give me some kind of explanation of what could have happened? (there can't be cache / query optimization stuff, because the queries were run in sync, and in a single thread, and it was far from affecting the cache this much) I should note that the bottleneck of the speed was in SQL server, using most of the CPU time.

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• Speeding up a group by date query on a big table in postgres

  - by zaius

  I've got a table with around 20 million rows. For arguments sake, lets say there are two columns in the table - an id and a timestamp. I'm trying to get a count of the number of items per day. Here's what I have at the moment. SELECT DATE(timestamp) AS day, COUNT(*) FROM actions WHERE DATE(timestamp) >= '20100101' AND DATE(timestamp) < '20110101' GROUP BY day; Without any indices, this takes about a 30s to run on my machine. Here's the explain analyze output: GroupAggregate (cost=675462.78..676813.42 rows=46532 width=8) (actual time=24467.404..32417.643 rows=346 loops=1) -> Sort (cost=675462.78..675680.34 rows=87021 width=8) (actual time=24466.730..29071.438 rows=17321121 loops=1) Sort Key: (date("timestamp")) Sort Method: external merge Disk: 372496kB -> Seq Scan on actions (cost=0.00..667133.11 rows=87021 width=8) (actual time=1.981..12368.186 rows=17321121 loops=1) Filter: ((date("timestamp") >= '2010-01-01'::date) AND (date("timestamp") < '2011-01-01'::date)) Total runtime: 32447.762 ms Since I'm seeing a sequential scan, I tried to index on the date aggregate CREATE INDEX ON actions (DATE(timestamp)); Which cuts the speed by about 50%. HashAggregate (cost=796710.64..796716.19 rows=370 width=8) (actual time=17038.503..17038.590 rows=346 loops=1) -> Seq Scan on actions (cost=0.00..710202.27 rows=17301674 width=8) (actual time=1.745..12080.877 rows=17321121 loops=1) Filter: ((date("timestamp") >= '2010-01-01'::date) AND (date("timestamp") < '2011-01-01'::date)) Total runtime: 17038.663 ms I'm new to this whole query-optimization business, and I have no idea what to do next. Any clues how I could get this query running faster?

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• Is this a bad indexing strategy for a table?

  - by llamaoo7

  The table in question is part of a database that a vendor's software uses on our network. The table contains metadata about files. The schema of the table is as follows Metadata ResultID (PK, int, not null) MappedFieldname (char(50), not null) Fieldname (PK, char(50), not null) Fieldvalue (text, null) There is a clustered index on ResultID and Fieldname. This table typically contains millions of rows (in one case, it contains 500 million). The table is populated by 24 workers running 4 threads each when data is being "processed". This results in many non-sequential inserts. Later after processing, more data is inserted into this table by some of our in-house software. The fragmentation for a given table is at least 50%. In the case of the largest table, it is at 90%. We do not have a DBA. I am aware we desperately need a DB maintenance strategy. As far as my background, I'm a college student working part time at this company. My question is this, is a clustered index the best way to go about this? Should another index be considered? Are there any good references for this type and similar ad-hoc DBA tasks?

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• How is an array stored in memory?

  - by George

  In an interest to delve deeper into how memory is allocated and stored, I have written an application that can scan memory address space, find a value, and write out a new value. I developed a sample application with the end goal to be able to programatically locate my array, and overwrite it with a new sequence of numbers. In this situation, I created a single dimensional array, with 5 elements, e.g. int[] array = new int[] {8,7,6,5,4}; I ran my application and searched for a sequence of the five numbers above. I was looking for any value that fell between 4 and 8, for a total of 5 numbers in a row. Unforuntately, my the sequential numbers in my array matched hundreds of results, as the numbers 4 through 8, in no particular sequence happened to be next to each other, in memory, in many situations. Is there any way to distinguish that a set of numbers within memory, represents an array, not simply integers that are next to each other? Is there any way of knowing that if I find a certain value, that the matching values proceeding it are that of an array? I would assume that when I declare int[] array, its pointing at the first address of my array, which would provide some kind of meta-data to what existed in the array, e.g. 0x123456789 meta-data, 5 - 32 bit integers 0x123456789 + 32 "8" 0x123456789 + 64 "7" 0x123456789 + 96 "6" 0x123456789 + 128 "5" 0x123456789 + 160 "4" Am I way off base?

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• Objective-measures of the expressiveness of programming languages [closed]

  - by Casebash

  I am very interested in the expressiveness of different languages. Everyone who has programmed in multiple languages knows that sometimes a language allows you to express concepts which you can't express in other languages. You can have all kinds of subjective discussion about this, but naturally it would be better to have an objective measure. There do actually exist objective measures. One is Turing-Completeness, which means that a language is capable of generating any output that could be generated by following a sequential set of steps. There are also other lesser levels of expressiveness such as Finite State Automata. Now, except for domain specific languages, pretty much all modern languages are Turing complete. It is therefore natural to ask the following question: Can we can define any other formal measures of expressiveness which are greater than Turing completeness? Now of course we can't define this by considering the output that a program can generate, as Turing machines can already produce the same output that any other program can. But there are definitely different levels in what concepts can be expressed - surely no-one would argue that assembly language is as powerful as a modern object oriented language like Python. You could use your assembly to write a Python interpreter, so clearly any accurate objective measure would have to exclude this possibility. This also causes a problem with trying to define the expressiveness using the minimum number of symbols. How exactly to do so is not clear and indeed appears extremely difficult, but we can't assume that just because we don't know how to solve a problem, that nobody know how to. It is also doesn't really make sense to demand a definition of expressiveness before answering the question - after all the whole point of this question is to obtain such a definition. I think that my explanation will be clear enough for anyone with a strong theoretical background in computer science to understand what I am looking for. If you do have such a background and you disagree, please comment why, but if you don't thats probably why you don't understand the question.

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• look up constants based on value.

  - by PLangeberg

  I have a 3rd party struct that is comprised of the following: [StructLayout(LayoutKind.Sequential, Size=1)] public struct BigBlueReasonCodes { public const int ABC_REASONCODE_DESCRIPTION01 = 1000; public const int ABC_REASONCODE_DESCRIPTION01 = 1005; public const int ABC_REASONCODE_DESCRIPTION01 = 1010; public const int DEF_REASONCODE_DESCRIPTION01 = 2001; public const int DEF_REASONCODE_DESCRIPTION01 = 2010; public const int DEF_REASONCODE_DESCRIPTION01 = 2013; public const int GHI_REASONCODE_DESCRIPTION01 = 3050; public const int GHI_REASONCODE_DESCRIPTION01 = 3051; public const int GHI_REASONCODE_DESCRIPTION01 = 3052; public const string JKL_REASONCODE_DESCRIPTION01 = "XYZ; public const string GHI_REASONCODE_DESCRIPTION01 = "ST"; static BigblueReasonCodes(); } I am trying to look up the reason description(the field name) based on the reason code(the value) so my class can do someting like: string failureReason = GetReasonDescription(reasoncode); Somethings of mention are some have int values and some have string values. I am only worried about the ones with int values. I also only want the ones that start with GHI_ if possible but not a big deal.

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• Programação paralela no .NET Framework 4 – Parte I

  - by anobre

  Introdução O avanço de tecnologia nos últimos anos forneceu, a baixo custo, acesso  a workstations com inúmeros CPUs. Facilmente encontramos hoje máquinas clientes com 2, 4 e até 8 núcleos, sem considerar os “super-servidores” com até 36 processadores :) Da wikipedia: A Unidade central de processamento (CPU, de acordo com as iniciais em inglês) ou o processador é a parte de um sistema de computador que executa as instruções de um programa de computador, e é o elemento primordial na execução das funções de um computador. Este termo tem sido usado na indústria de computadores pelo menos desde o início dos anos 1960[1]. A forma, desenho e implementação de CPUs têm mudado dramaticamente desde os primeiros exemplos, mas o seu funcionamento fundamental permanece o mesmo. Fazendo uma analogia, seria muito interessante delegarmos tarefas no mundo real que podem ser executadas independentemente a pessoas diferentes, atingindo desta forma uma  maior performance / produtividade na sua execução. A computação paralela se baseia na idéia que um problema maior pode ser dividido em problemas menores, sendo resolvidos de forma paralela. Este pensamento é utilizado há algum tempo por HPC (High-performance computing), e através das facilidades dos últimos anos, assim como a preocupação com consumo de energia, tornaram esta idéia mais atrativa e de fácil acesso a qualquer ambiente. No .NET Framework A plataforma .NET apresenta um runtime, bibliotecas e ferramentas para fornecer uma base de acesso fácil e rápido à programação paralela, sem trabalhar diretamente com threads e thread pool. Esta série de posts irá apresentar todos os recursos disponíveis, iniciando os estudos pela TPL, ou Task Parallel Library. Task Parallel Library A TPL é um conjunto de tipos localizados no namespace System.Threading e System.Threading.Tasks, a partir da versão 4 do framework. A partir da versão 4 do framework, o TPL é a maneira recomendada para escrever código paralelo e multithreaded. http://msdn.microsoft.com/en-us/library/dd460717(v=VS.100).aspx Task Parallelism O termo “task parallelism”, ou em uma tradução live paralelismo de tarefas, se refere a uma ou mais tarefas sendo executadas de forma simultanea. Considere uma tarefa como um método. A maneira mais fácil de executar tarefas de forma paralela é o código abaixo: Parallel.Invoke(() => TrabalhoInicial(), () => TrabalhoSeguinte()); O que acontece de verdade? Por trás nos panos, esta instrução instancia de forma implícita objetos do tipo Task, responsável por representar uma operação assíncrona, não exatamente paralela: public class Task : IAsyncResult, IDisposable É possível instanciar Tasks de forma explícita, sendo uma alternativa mais complexa ao Parallel.Invoke. var task = new Task(() => TrabalhoInicial()); task.Start(); Outra opção de instanciar uma Task e já executar sua tarefa é: var t = Task<int>.Factory.StartNew(() => TrabalhoInicialComValor());var t2 = Task<int>.Factory.StartNew(() => TrabalhoSeguinteComValor()); A diferença básica entre as duas abordagens é que a primeira tem início conhecido, mais utilizado quando não queremos que a instanciação e o agendamento da execução ocorra em uma só operação, como na segunda abordagem. Data Parallelism Ainda parte da TPL, o Data Parallelism se refere a cenários onde a mesma operação deva ser executada paralelamente em elementos de uma coleção ou array, através de instruções paralelas For e ForEach. A idéia básica é pegar cada elemento da coleção (ou array) e trabalhar com diversas threads concomitantemente. A classe-chave para este cenário é a System.Threading.Tasks.Parallel // Sequential version foreach (var item in sourceCollection) { Process(item); } // Parallel equivalent Parallel.ForEach(sourceCollection, item => Process(item)); Complicado né? :) Demonstração Acesse aqui um vídeo com exemplos (screencast). Cuidado! Apesar da imensa vontade de sair codificando, tome cuidado com alguns problemas básicos de paralelismo. Neste link é possível conhecer algumas situações. Abraços.

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• Silverlight Cream for March 25, 2010 -- #820

  - by Dave Campbell

  In this Issue: René Schulte, Jeremy Likness, Hassan, Victor Gaudioso, SilverLaw, Mike Taulty, Phani Raj, Tim Heuer, Christian Schormann, Brad Abrams, David Anson, Diptimaya Patra, and Daniel Vaughan. Shoutouts: Last week, Koen Zwikstra announced Silverlight Spy at MIX10 Anand Iyer announced this for students on the Windows Team Blog: Be a Windows Phone 7 “Rockstar” Justin Angel blogged that Silverlight Isn't Fully Cross-Platform ... let him know if you think it's a yawn or important. On behalf of SilverlightShow, Cigdem Patlak posted MIX10: Laurent Bugnion on Silverlight adoption, WP7 and the EcoContest From SilverlightCream.com: Coding4Fun - Silverlight Real Time Face Detection René Schulte has a Coding 4 Fun article posted on facial recognition. Who better to be manipulating graphics like this than René? Sequential Asynchronous Workflows Part 2: Simplified Jeremy Likness follows up his previous post with another one that is 'simplified'. Remember his previous post began with a post on the Silverlight.net forum and Rob Eisenburg's MVVM presentation from MIX10 Windows Phone 7 Video Tutorial Hassan has a new video up on his AfricanGeek site, and that's a continuation of his previous WP7 video tutorial, adding a listbox and databinding it to the selected index of another listbox. The Los Angeles Silverlight Usergorup will be Streaming its March Meeting LIVE in Silverlight – Tonight! Victor Gaudioso used his Live Streaming knowledge to stream his User Group meeting last night from LA where Michael Washington presented on MVVM followed by Victor himself. That was last night. Today he has a couple of the videos up to view. Shining 3D Font Design - Silverlight 3 SilverLaw has a "Shining 3D Font" tutorial up, and a video on it here: New Video: How to create a 3D effect on a Silverlight 3 Textblock ... this is also available in the Expression Gallery. Silverlight 4 RC – Signing trusted apps with home made certificates Mike Taulty has a post up about building a hand-rolled cert to test out the XAP signing features, and then gives a nod to John Papa with a link to the Silverlight White Paper I've posted about before, because this info is in there as well. Developing a Windows Phone 7 Application that consumes OData Phani Raj has a tutorial up on consuming the NetFlix OData catalog on the WP7 emulator ... now *that* is cool! Make your Silverlight applications Speak to you with Microsoft Translator Tim Heuer used Silverlight to demonstrate Microsoft Translator as a speech synthesis tool using the Speak API included ... pretty cool, Tim ... lots of external links and code. Blend 4: About Path Layout, Sidebar – More About ListBox Than You Ever Wanted To Know Christian Schormann has another outstanding tutorial up on the ListBox and PathLayout in Expression Blend ... just check out the screen shots and you'll wanna read it! Silverlight 4 + RIA Services: Ready for Business: Updating Data in the Client This is the continuation of Brad Abrams' series on WCF RIA Services and is a tutorial on setting up to deal with updating the data. Tip: The CLR wrapper for a DependencyProperty should do its job and nothing more David Anson is posting some "Development Tips", and this is the first ... discussing making sure your DependencyProperty CLR wrapper stays on point... Create and Apply Theme Silverlight Application Diptimaya Patra has a tutorial up on creating and using themes. He states that "Themes are nothing but some predefined styles" ... check it out and see if it's really that easy :) Building a Windows Phone 7 Puzzle Game Daniel Vaughan has a great post up starting with installing all the tools and ending with a maze game for WP7 using XNA for sound... this is the first I've seen that integrates XNA (I think). Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone    MIX10

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• Silverlight Cream for March 23, 2010 -- #818

  - by Dave Campbell

  In this Issue: Max Paulousky, Jeremy Likness, Mark Tucker, Christian Schormann, Page Brooks, Brad Abrams(-2-), Jeff Wilcox, Unnir, Bea Stollnitz, John Papa and Adam Kinney, and Bill Reiss(-2-). Shoutouts: Ashish Shetty posted his material from his MIX10 presentation: Stepping outside the browser with Silverlight 4 Not Silverlight, but dang useful, Karl Shifflett posted a Visual Studio 2010 XAML Editor IntelliSense Presenter Extension Yavor Georgiev posted his MIX10 material: Two samples from today's MIX talk From SilverlightCream.com: GroupBox Sketching Control for WPF applications Using Blend Max Paulousky creates a GroupBox control for SketchFlow for WPF. He includes a link to an example of doing the same for Silverlight. Sequential Asynchronous Workflows in Silverlight using Coroutines Jeremy Likness' latest post begann with a post on the Silverlight.net forum and Rob Eisenburg's MVVM presentation from MIX10 resulting in the use of Wintellect's PowerThreading library (downloadable), and Coroutines. Windows Phone 7 UI Templates Mark Tucker has been putting a lot of thought into WP7 apps and produced 5 templates for building apps, downloadable in PowerPoint format. He's also looking to discuss this concept. Blend 4: About Path Layout, Part I Christian Schormann has a great tutorial up about Expression Blend 4 and path layout ... this is lots of great info, and it's only part 1! Custom Splash Screen for Windows Phone Page Brooks makes very quick work of showing how to add a splash screen to your WP7 app... very nice, Page! Silverlight 4 + RIA Services - Ready for Business: Exposing Data from Entity Framework Brad Abrams next post in the series is is on pulling your data from wherever it lives, and uses a DomainService to shape it for your Silverlight app. Silverlight 4 + RIA Services - Ready for Business: Consuming Data in the Silverlight Client Brad Abrams then discusses consuming that data in a Silverlight app. Not much code involvement at all.. great ROI :) Building Silverlight 3 and Silverlight 4 applications on a .NET 3.5 build machine Jeff Wilcox talks about building Silverlight 3 and Silverlight 4B both on a .NET 3.5 machine. He then adds in the Toolkit, and even WCF RIA Services. Expression Blend 4 - XAML generation tweaks Unnir demonstrates a few changes to Expression Blend 4 that produce more compact XAML. He's also asking for other examples you'd like to see tightened up. How can I sort a hierarchy? Bea Stollnitz posts plausible solutions to sorting data items at each level of a hierarchical UI, with descriptions of why they don't work, followed by the real deal... Silverlight and WPF. Silverlight Training Course (Silverlight 4) John Papa and Adam Kinney have posted a huge body of work to get us up-to-speed on Silverlight 4 -- a WhitePaper, hands-on labs, and an 8-unit course with 25 accompanying videos... geez... Silverlight game development on Windows Phone 7 Bill Reiss has a post up discussing game development on WP7 in general and then discusses his SilverSprite library, with a link to it. XNA or Silverlight for Windows Phone 7 game development? Bill Reiss next discusses the advantage of using Silverlight or XNA for your WP7 game development, and who better to discuss both? Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• WEB203 &ndash; Jump into Silverlight!&hellip; and Become Effective Immediately with Tim Huckaby, Fou

  - by Robert Burger

  Getting ready for the good stuff. Definitely wish there were more Silverlight and WCF RIA sessions, but this is a start.  Was lucky to get a coveted power-enabled seat.  Luckily, due to my trustily slow Verizon data card, I can get these notes out amidst a total Internet outage here.  This is the second breakout session of the day, and is by far standing-room only.  I stepped out before the session started to get a cool Diet COKE and wouldn’t have gotten back in if I didn’t already have a seat. Tim says this is an intro session and that he’s been begging for intro sessions at TechEd for years and that by looking at this audience, he thinks the demand is there.  Admittedly, I didn’t know this was an intro session, or I might have gone elsewhere.  But, it was the very first Silverlight session, so I had to be here. Tim says he will be providing a very good comprehensive reference application at the end of the presentation.  He has just demoed it, and it is a full CRUD-based Sales Manager application based on…  AdventureWorks! Session Agenda What it is / How to get started Declarative Programming Layout and Controls, Events and Commands Working with Data Adding Style to Your Application   Silverlight…  “WPF Light” Why is the download 4.2MB?  Because the direct competitor is a 4.2MB download.  There is no technical reason it is not the entire framework.  It is purely to “be competitive”.   Getting Started Get all of the following downloads from www.silverlight.net/getstarted Install VS2010 or Visual Web Developer Express 2010 Install Silverlight 4 Tools for VS2010 Install Expression Blend 4 Install the Silverlight 4 Toolkit   Reference Application Features Uses MVVM pattern – a way to move data access code that would normally be inline within the UI and placing it in nice data access libraries Images loaded dynamically from the database, converting GIF to PNG because Silverlight does not support GIF. LINQ to SQL is the data access model WCF is the data provider and is using binary message encoding   Declarative Programming XAML replaces code for UI representation Attributes control Layout and Style Event handlers wired-up in XAML Declarative Data Binding   Layout Overview Content rendering flows inside of parent Fixed positioning (Canvas) is seldom used Panels are used to house content Margins and Padding over fixed size   Panels StackPanel – Arranges child elements into a single line oriented horizontally or vertically Grid – A flexible grid are that consists of rows and columns Canvas – An are where positions are specifically fixed WrapPanel (in Toolkit) – Positions child elements in sequential position left to right and top to bottom. DockPanel (in Toolkit) – Positions child controls within a dockable area   Positioning Horizontal and Vertical Alignment Margin – Separates an element from neighboring elements Padding – Enlarges the effective size of an element by a thickness   Controls Overview Not all controls created equal Silverlight, as a subset of WPF, so many WPF controls do not exist in the core Siverlight release Silverlight Toolkit continues to add controls, but are released in different quality bands Plenty of good 3rd party controls to fill the gaps Windows Phone 7 is to have 95% of controls available in Silverlight Core and Toolkit.   Events and Commands Standard .NET Events Routed Events Commands – based on the ICommand interface – logical action that can be invoked in several ways   Adding Style to Your Application Resource Dictionaries – Contains a hash table of key/value pairs.  Silverlight can only use Static Resources whereas WPF can also use Dynamic Resources Visual State Manager Silverlight 4 supports Implicit styles ResourceDictionary.MergedDictionaries combines many different file-based resources   Downloads

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• JustMock is here !!

  - by mehfuzh

  As announced earlier by Hristo Kosev at Telerik blogs , we have started giving out JustMock builds from today. This is the first of early builds before the official Q2 release and we are pretty excited to get your feedbacks. Its pretty early to say anything on it. It actually depends on your feedback. To add few, with JustMock we tried to build a mocking tool with simple and intuitive syntax as possible excluding more and more noises and avoiding any smell that can be made to your code [We are still trying everyday] and we want to make the tool even better with your help. JustMock can be used to mock virtually anything. Moreover, we left an option open that it can be used to reduce / elevate the features  just though a single click. We tried to make a strong API and make stuffs fluent and guided as possible so that you never have the chance to get de-railed. Our syntax is AAA (Arrange – Act – Assert) , we don’t believe in Record – Reply model which some of the smarter mocking tools are planning to remove from their coming release or even don’t have [its always fun to lean from each other]. Overall more signals equals more complexity , reminds me of 37 signals :-). Currently, here are the things you can do with JustMock ( will cover more in-depth in coming days) Proxied mode Mock interfaces and class with virtuals Mock properties that includes indexers Set raise event for specific calls Use matchers to control mock arguments Assert specific occurrence of a mocked calls. Assert using matchers Do recursive mocks Do Sequential mocking ( same method with argument returns different values or perform different tasks) Do strict mocking (by default and i prefer loose , so that i can use it as stubs) Elevated mode Mock static calls Mock final class Mock sealed classes Mock Extension methods Partially mock a  class member directly using Mock.Arrange Mock MsCorlib (we will support more and more members in coming days) , currently we support FileInfo, File and DateTime. These are few, you need to take a look at the test project that is provided with the build to find more [Along with the document]. Also, one of feature that will i will be using it for my next OS projects is the ability to run it separately in  proxied mode which makes it easy to redistribute and do some personal development in a more DI model and my option to elevate as it go.   I’ve surely forgotten tons of other features to mention that i will cover time but  don’t for get the URL : www.telerik.com/justmock   Finally a little mock code:   var lvMock = Mock.Create<ILoveJustMock>();    // set your goal  Mock.Arrange(() => lvMock.Response(Arg.Any<string>())).Returns((int result) => result);    //perform  string ret =  lvMock.Echo("Yes");    Assert.Equal(ret, "Yes");  // make sure everything is fine  Mock.Assert(() => lvMock.Echo("Yes"), Occurs.Once());   Hope that helps to get started,  will cover if not :-).

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• The enterprise vendor con - connecting SSD's using SATA 2 (3Gbits) thus limiting there performance

  - by tonyrogerson

  When comparing SSD against Hard drive performance it really makes me cross when folk think comparing an array of SSD running on 3GBits/sec to hard drives running on 6GBits/second is somehow valid. In a paper from DELL (http://www.dell.com/downloads/global/products/pvaul/en/PowerEdge-PowerVaultH800-CacheCade-final.pdf) on increasing database performance using the DELL PERC H800 with Solid State Drives they compare four SSD drives connected at 3Gbits/sec against ten 10Krpm drives connected at 6Gbits [Tony slaps forehead while shouting DOH!]. It is true in the case of hard drives it probably doesn’t make much difference 3Gbit or 6Gbit because SAS and SATA are both end to end protocols rather than shared bus architecture like SCSI, so the hard drive doesn’t share bandwidth and probably can’t get near the 600MiBytes/second throughput that 6Gbit gives unless you are doing contiguous reads, in my own tests on a single 15Krpm SAS disk using IOMeter (8 worker threads, queue depth of 16 with a stripe size of 64KiB, an 8KiB transfer size on a drive formatted with an allocation size of 8KiB for a 100% sequential read test) I only get 347MiBytes per second sustained throughput at an average latency of 2.87ms per IO equating to 44.5K IOps, ok, if that was 3GBits it would be less – around 280MiBytes per second, oh, but wait a minute [...fingers tap desk] You’ll struggle to find in the commodity space an SSD that doesn’t have the SATA 3 (6GBits) interface, SSD’s are fast not only low latency and high IOps but they also offer a very large sustained transfer rate, consider the OCZ Agility 3 it so happens that in my masters dissertation I did the same test but on a difference box, I got 374MiBytes per second at an average latency of 2.67ms per IO equating to 47.9K IOps – cost of an 240GB Agility 3 is £174.24 (http://www.scan.co.uk/products/240gb-ocz-agility-3-ssd-25-sata-6gb-s-sandforce-2281-read-525mb-s-write-500mb-s-85k-iops), but that same drive set in a box connected with SATA 2 (3Gbits) would only yield around 280MiBytes per second thus losing almost 100MiBytes per second throughput and a ton of IOps too. So why the hell are “enterprise” vendors still only connecting SSD’s at 3GBits? Well, my conspiracy states that they have no interest in you moving to SSD because they’ll lose so much money, the argument that they use SATA 2 doesn’t wash, SATA 3 has been out for some time now and all the commodity stuff you buy uses it now. Consider the cost, not in terms of price per GB but price per IOps, SSD absolutely thrash Hard Drives on that, it was true that the opposite was also true that Hard Drives thrashed SSD’s on price per GB, but is that true now, I’m not so sure – a 300GByte 2.5” 15Krpm SAS drive costs £329.76 ex VAT (http://www.scan.co.uk/products/300gb-seagate-st9300653ss-savvio-15k3-25-hdd-sas-6gb-s-15000rpm-64mb-cache-27ms) which equates to £1.09 per GB compared to a 480GB OCZ Agility 3 costing £422.10 ex VAT (http://www.scan.co.uk/products/480gb-ocz-agility-3-ssd-25-sata-6gb-s-sandforce-2281-read-525mb-s-write-410mb-s-30k-iops) which equates to £0.88 per GB. Ok, I compared an “enterprise” hard drive with a “commodity” SSD, ok, so things get a little more complicated here, most “enterprise” SSD’s are SLC and most commodity are MLC, SLC gives more performance and wear, I’ll talk about that another day. For now though, don’t get sucked in by vendor marketing, SATA 2 (3Gbit) just doesn’t cut it, SSD need 6Gbit to breath and even that SSD’s are pushing. Alas, SSD’s are connected using SATA so all the controllers I’ve seen thus far from HP and DELL only do SATA 2 – deliberate? Well, I’ll let you decide on that one.

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• Creating a Synchronous BPEL composite using File Adapter

  - by [email protected]

  By default, the JDeveloper wizard generates asynchronous WSDLs when you use technology adapters. Typically, a user follows these steps when creating an adapter scenario in 11g: 1) Create a SOA Application with either "Composite with BPEL" or an "Empty Composite". Furthermore, if  the user chooses "Empty Composite", then he or she is required to drop the "BPEL Process" from the "Service Components" pane onto the SOA Composite Editor. Either way, the user comes to the screen below where he/she fills in the process details. Please note that the user is required to choose "Define Service Later" as the template. 2) Creates the inbound service and outbound references and wires them with the BPEL component:     3) And, finally creates the BPEL process with the initiating <receive> activity to retrieve the payload and an <invoke> activity to write the payload.     This is how most BPEL processes that use Adapters are modeled. And, if we scrutinize the generated WSDL, we can clearly see that the generated WSDL is one way and that makes the BPEL process asynchronous (see below)   In other words, the inbound FileAdapter would poll for files in the directory and for every file that it finds there, it would translate the content into XML and publish to BPEL. But, since the BPEL process is asynchronous, the adapter would return immediately after the publish and perform the required post processing e.g. deletion/archival and so on.  The disadvantage with such asynchronous BPEL processes is that it becomes difficult to throttle the inbound adapter. In otherwords, the inbound adapter would keep sending messages to BPEL without waiting for the downstream business processes to complete. This might lead to several issues including higher memory usage, CPU usage and so on. In order to alleviate these problems, we will manually tweak the WSDL and BPEL artifacts into synchronous processes. Once we have synchronous BPEL processes, the inbound adapter would automatically throttle itself since the adapter would be forced to wait for the downstream process to complete with a <reply> before processing the next file or message and so on. Please see the tweaked WSDL below and please note that we have converted the one-way to a two-way WSDL and thereby making the WSDL synchronous: Add a <reply> activity to the inbound adapter partnerlink at the end of your BPEL process e.g.   Finally, your process will look like this:   You are done.   Please remember that such an excercise is NOT required for Mediator since the Mediator routing rules are sequential by default. In other words, the Mediator uses the caller thread (inbound file adapter thread) for processing the routing rules. This is the case even if the WSDL for mediator is one-way.

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• SQL SERVER – Partition Parallelism Support in expressor 3.6

  - by pinaldave

  I am very excited to learn that there is a new version of expressor’s data integration platform coming out in March of this year.  It will be version 3.6, and I look forward to using it and telling everyone about it.  Let me describe a little bit more about what will be so great in expressor 3.6: Greatly enhanced user interface Parallel Processing Bulk Artifact Upgrading The User Interface First let me cover the most obvious enhancements. The expressor Studio user interface (UI) has had some significant work done. Kudos to the expressor Engineering team; the entire UI is a visual masterpiece that is very responsive and intuitive. The improvements are more than just eye candy; they provide significant productivity gains when developing expressor Dataflows. Operator shape icons now include a description that identifies the function of each operator, instead of having to guess at the function by the icon. Operator shapes and highlighting depict the current function and status: Disabled, enabled, complete, incomplete, and error. Each status displays an appropriate message in the message panel with correction suggestions. Floating or docking property panels provide descriptive tool tips for each property as well as auto resize when adjusting the canvas, without having to search Help or the need to scroll around to get access to the property. Progress and status indicators let you know when an operation is working. “No limit” canvas with snap-to-grid allows automatic sizing and accurate positioning when you have numerous operators in the Dataflow. The inline tool bar offers quick access to pan, zoom, fit and overview functions. Selecting multiple artifacts with a right click context allows you to easily manage your workspace more efficiently. Partitioning and Parallel Processing Partitioning allows each operator to process multiple subsets of records in parallel as opposed to processing all records that flow through that operator in a single sequential set. This capability allows the user to configure the expressor Dataflow to run in a way that most efficiently utilizes the resources of the hardware where the Dataflow is running. Partitions can exist in most individual operators. Using partitions increases the speed of an expressor data integration application, therefore improving performance and load times. With the expressor 3.6 Enterprise Edition, expressor simplifies enabling parallel processing by adding intuitive partition settings that are easy to configure. Bulk Artifact Upgrading Bulk Artifact Upgrading sounds a bit intimidating, but it actually is not and it is a welcome addition to expressor Studio. In past releases, users were prompted to confirm that they wanted to upgrade their individual artifacts only when opened. This was a cumbersome and repetitive process. Now with bulk artifact upgrading, a user can easily select what artifact or group of artifacts to upgrade all at once. As you can see, there are many new features and upgrade options that will prove to make expressor Studio quicker and more efficient.  I hope I’m not the only one who is excited about all these new upgrades, and that I you try expressor and share your experience with me. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Technology

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• How to write simple code using TDD [migrated]

  - by adeel41

  Me and my colleagues do a small TDD-Kata practice everyday for 30 minutes. For reference this is the link for the excercise http://osherove.com/tdd-kata-1/ The objective is to write better code using TDD. This is my code which I've written public class Calculator { public int Add( string numbers ) { const string commaSeparator = ","; int result = 0; if ( !String.IsNullOrEmpty( numbers ) ) result = numbers.Contains( commaSeparator ) ? AddMultipleNumbers( GetNumbers( commaSeparator, numbers ) ) : ConvertToNumber( numbers ); return result; } private int AddMultipleNumbers( IEnumerable getNumbers ) { return getNumbers.Sum(); } private IEnumerable GetNumbers( string separator, string numbers ) { var allNumbers = numbers .Replace( "\n", separator ) .Split( new string[] { separator }, StringSplitOptions.RemoveEmptyEntries ); return allNumbers.Select( ConvertToNumber ); } private int ConvertToNumber( string number ) { return Convert.ToInt32( number ); } } and the tests for this class are [TestFixture] public class CalculatorTests { private int ArrangeAct( string numbers ) { var calculator = new Calculator(); return calculator.Add( numbers ); } [Test] public void Add_WhenEmptyString_Returns0() { Assert.AreEqual( 0, ArrangeAct( String.Empty ) ); } [Test] [Sequential] public void Add_When1Number_ReturnNumber( [Values( "1", "56" )] string number, [Values( 1, 56 )] int expected ) { Assert.AreEqual( expected, ArrangeAct( number ) ); } [Test] public void Add_When2Numbers_AddThem() { Assert.AreEqual( 3, ArrangeAct( "1,2" ) ); } [Test] public void Add_WhenMoreThan2Numbers_AddThemAll() { Assert.AreEqual( 6, ArrangeAct( "1,2,3" ) ); } [Test] public void Add_SeparatorIsNewLine_AddThem() { Assert.AreEqual( 6, ArrangeAct( @"1 2,3" ) ); } } Now I'll paste code which they have written public class StringCalculator { private const char Separator = ','; public int Add( string numbers ) { const int defaultValue = 0; if ( ShouldReturnDefaultValue( numbers ) ) return defaultValue; return ConvertNumbers( numbers ); } private int ConvertNumbers( string numbers ) { var numberParts = GetNumberParts( numbers ); return numberParts.Select( ConvertSingleNumber ).Sum(); } private string[] GetNumberParts( string numbers ) { return numbers.Split( Separator ); } private int ConvertSingleNumber( string numbers ) { return Convert.ToInt32( numbers ); } private bool ShouldReturnDefaultValue( string numbers ) { return String.IsNullOrEmpty( numbers ); } } and the tests [TestFixture] public class StringCalculatorTests { [Test] public void Add_EmptyString_Returns0() { ArrangeActAndAssert( String.Empty, 0 ); } [Test] [TestCase( "1", 1 )] [TestCase( "2", 2 )] public void Add_WithOneNumber_ReturnsThatNumber( string numberText, int expected ) { ArrangeActAndAssert( numberText, expected ); } [Test] [TestCase( "1,2", 3 )] [TestCase( "3,4", 7 )] public void Add_WithTwoNumbers_ReturnsSum( string numbers, int expected ) { ArrangeActAndAssert( numbers, expected ); } [Test] public void Add_WithThreeNumbers_ReturnsSum() { ArrangeActAndAssert( "1,2,3", 6 ); } private void ArrangeActAndAssert( string numbers, int expected ) { var calculator = new StringCalculator(); var result = calculator.Add( numbers ); Assert.AreEqual( expected, result ); } } Now the question is which one is better? My point here is that we do not need so many small methods initially because StringCalculator has no sub classes and secondly the code itself is so simple that we don't need to break it up too much that it gets confusing after having so many small methods. Their point is that code should read like english and also its better if they can break it up earlier than doing refactoring later and third when they will do refactoring it would be much easier to move these methods quite easily into separate classes. My point of view against is that we never made a decision that code is difficult to understand so why we are breaking it up so early. So I need a third person's opinion to understand which option is much better.

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 6

  - by MarkPearl

  Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity flowing through a coil produces a magnetic field. Electric pulses are sent to the write head, and the resulting magnetic patterns are recorded on the surface below with different patterns for positive and negative currents The physical characteristics of a magnetic disk   Summarize from book   The factors that play a role in the performance of a disk Seek time – the time it takes to position the head at the track Rotational delay / latency – the time it takes for the beginning of the sector to reach the head Access time – the sum of the seek time and rotational delay Transfer time – the time it takes to transfer data RAID The rate of improvement in secondary storage performance has been considerably less than the rate for processors and main memory. Thus secondary storage has become a bit of a bottleneck. RAID works on the concept that if one disk can be pushed so far, additional gains in performance are to be had by using multiple parallel components. Points to note about RAID… RAID is a set of physical disk drives viewed by the operating system as a single logical drive Data is distributed across the physical drives of an array in a scheme known as striping Redundant disk capacity is used to store parity information, which guarantees data recoverability in case of a disk failure (not supported by RAID 0 or RAID 1) Interesting to note that the increase in the number of drives, increases the probability of failure. To compensate for this decreased reliability RAID makes use of stored parity information that enables the recovery of data lost due to a disk failure.   The RAID scheme consists of 7 levels…   Category Level Description Disks Required Data Availability Large I/O Data Transfer Capacity Small I/O Request Rate Striping 0 Non Redundant N Lower than single disk Very high Very high for both read and write Mirroring 1 Mirrored 2N Higher than RAID 2 – 5 but lower than RAID 6 Higher than single disk Up to twice that of a signle disk for read Parallel Access 2 Redundant via Hamming Code N + m Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Parallel Access 3 Bit interleaved parity N + 1 Much higher than single disk Highest of all listed alternatives Approximately twice that of a single disk Independent Access 4 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, significantly lower than single disk for write Similar to RAID 0 for read, significantly lower than single disk for write Independent Access 5 Block interleaved parity N + 1 Much higher than single disk Similar to RAID 0 for read, lower than single disk for write Similar to RAID 0 for read, generally  lower than single disk for write Independent Access 6 Block interleaved parity N + 2 Highest of all listed alternatives Similar to RAID 0 for read; lower than RAID 5 for write Similar to RAID 0 for read, significantly lower than RAID 5  for write   Read page 215 – 221 for detailed explanation on RAID levels Optical Memory There are a variety of optical-disk systems available. Read through the table on page 222 – 223 Some of the devices include… CD CD-ROM CD-R CD-RW DVD DVD-R DVD-RW Blue-Ray DVD Magnetic Tape Most modern systems use serial recording – data is lade out as a sequence of bits along each track. The typical recording used in serial is referred to as serpentine recording. In this technique when data is being recorded, the first set of bits is recorded along the whole length of the tape. When the end of the tape is reached the heads are repostioned to record a new track, and the tape is again recorded on its whole length, this time in the opposite direction. That process continued back and forth until the tape is full. To increase speed, the read-write head is capable of reading and writing a number of adjacent tracks simultaneously. Data is still recorded serially along individual tracks, but blocks in sequence are stored on adjacent tracks as suggested. A tape drive is a sequential access device. Magnetic tape was the first kind of secondary memory. It is still widely used as the lowest-cost, slowest speed member of the memory hierarchy.

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• Easy Made Easier - Networking

  - by dragonfly

      In my last post, I highlighted the feature of the Appliance Manager Configurator to auto-fill some fields based on previous field values, including host names based on System Name and sequential IP addresses from the first IP address entered. This can make configuration a little faster and a little less subject to data entry errors, particularly if you are doing the configuration on the Oracle Database Appliance itself.     The Oracle Database Appliance Appliance Manager Configurator is available for download here. But why would you download it, if it comes pre-installed on the Oracle Database Appliance? A common reason for customers interested in this new Engineered System is to get a good idea of how easy it is to configure. Beyond that, you can save the resulting configuration as a file, and use it on an Oracle Database Appliance. This allows you to verify the data entered in advance, and in the comfort of your office. In addition, the topic of this post is another strong reason to download and use the Appliance Manager Configurator prior to deploying your Oracle Database Appliance.     The most common source of hiccups in deploying an Oracle Database Appliance, based on my experiences with a variety of customers, involves the network configuration. It is during Step 11, when network validation occurs, that these come to light, which is almost half way through the 24 total steps, and can be frustrating, whether it was a typo, DNS mis-configuration or IP address already in use. This is why I recommend as a best practice taking advantage of the Appliance Manager Configurator prior to deploying an Oracle Database Appliance.     Why? Not only do you get the benefit of being able to double check your entries before you even start on the Oracle Database Appliance, you can also take advantage of the Network Validation step. This is the final step before you review all the data and can save it to a text file. It can be skipped, if you aren't ready or are not connected to the network that the Oracle Database Appliance will be on. My recommendation, though, is to run the Appliance Manager Configurator on your laptop, enter the data or re-load a previously saved file of the data, and then connect to the network that the Oracle Database Appliance will be on. Now run the Network Validation. It will check to make sure that the host names you entered are in DNS and do resolve to the IP addresses you specifiied. It will also ping the IP Addresses you specified, so that you can verify that no other machine is already using them (yes, that has happened at customer sites).     After you have completed the validation, as seen in the screen shot below, you can review the results and move on to saving your settings to a file for use on your Oracle Database Appliance, or if there are errors, you can use the Back button to return to the appropriate screen and correct the data. Once you are satisfied with the Network Validation, just check the Skip/Ignore Network Validation checkbox at the top of the screen, then click Next. Is the Network Validation in the Appliance Manager Configurator required? No, but it can save you time later. I should also note that the Network Validation screen is not part of the Appliance Manager Configurator that currently ships on the Oracle Database Appliance, so this is the easiest way to verify your network configuration.     I hope you are finding this series of posts useful. My next post will cover some aspects of the windowing environment that gets run by the 'startx' command on the Oracle Database Appliance, since this is needed to run the Appliance Manager Configurator via a direct connected monitor, keyboard and mouse, or via the ILOM. If it's been a while since you've used an OpenWindows environment, you'll want to check it out.

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• WiX, MSDeploy and an appealing configuration/deployment paradigm

  - by alexhildyard

  I do a lot of application and server configuration; I've done this for many years and have tended to view the complexity of this strictly in terms of the complexity of the ultimate configuration to be deployed. For example, specific APIs aside, I would tend to regard installing a server certificate as a more complex activity than, say, copying a file or adding a Registry entry.My prejudice revolved around the idea of a sequential deployment script that not only had the explicit prescription to apply a specific server configuration, but also made the implicit presumption that the server in question was in a good known state. Scripts like this fail for hundreds of reasons -- the Default Website didn't exist; the application had already been deployed; the application had already been partially deployed and failed to rollback fully, and so on. And so the problem is that the more complex the configuration activity, the more scope for error in any individual part of that activity, and therefore the greater the chance the server in question will not end up at exactly the desired configuration level.Recently I was introduced to a completely different mindset, which, for want of a better turn of phrase, I will call the "make it so" mindset. It's extremely simple both to explain and to implement. In place of the head-down, imperative script you used to use, you substitute a set of checks -- much like exception handlers -- around each configuration activity, starting with a check of the current system state. Thus the configuration logic becomes: "IF these services aren't started then start them, and IF XYZ website doesn't exist then create it, and IF these shares don't exist then create them, and IF these shares aren't permissioned in some particular way, then permission them so." This works. Really well, in my experience. Scenario 1: You want to get a system into a good known state; it's already in a good known state; you quickly realise there is nothing to do.Scenario 2: You want to get the system into a good known state; your script is flawed or the system is bust; it cannot be put into that state. You know exactly where (at least part of) the problem is and why.Scenario 3: You want to get the system into a good known state; people are fiddling around with the system just now. That's fine. You do what you can, and later you come back and try it againScenario 4: No one wants to deploy anything; they want you to prove that the previous deployment was successful. So you re-run the deployment script with the "-WhatIf" flag. It reports that there was nothing to change. There's your proof.I mentioned two technologies in the title -- MSI and MSDeploy. I am thinking specifically of the conversation that took place here. Having worked with both technologies, I think Rob Mensching's response is appropriately nuanced, and in essence the difference is this: sometimes your target is either to achieve a specific new server state, or to rollback to a known good one. Then again, your target may be to configure what you can, and to understand what you can't. Implicitly MSDeploy's "rollback" is simply to redeploy the previous version, whereas a well-crafted MSI will actively put your system into that state without further intervention. Either way, if all goes well it will leave you with a system in one of two states, whereas MSDeploy could leave your system in one of many states. The key is that MSDeploy and MSI are complementary technologies; which suits you best depends as much on Operational guidance as your Configuration remit.What I wanted to say was that I have always been for atomic, transactional-based configuration, but having worked with the "make it so" paradigm, I have been favourably impressed by the actual results. I'm tempted to put a more technical post up on this in due course.

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• How to make a stack stable? Need help for an explicit resting contact scheme (2-dimensional)

  - by Register Sole

  Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based method with Projected-Gauss-Seidel (PGS) iterative solver as described by Erin Catto (mentioned in the reference of the paper as [Catt05]). So here's how it currently is: The simulation handles 2-dimensional rotating convex polygons. Detection is using separating-axis test, with a SKIN, meaning closest points between two polygons is detected and determined if their distance is less than SKIN. To resolve collision, simultaneous impulse-based method is used. It is solved using iterative solver (PGS-solver) as in Erin Catto's paper. Error-correction is implemented using Baumgarte's stabilization (you can refer to either paper for this) using J V = beta/dt*overlap, J is the Jacobian for the constraints, V the matrix containing the velocities of the bodies, beta an error-correction parameter that is better be < 1, dt the time-step taken by the engine, and overlap, the overlap between the bodies (true overlap, so SKIN is ignored). However, it is still less stable than I expected :s I tried to stack hexagons (or squares, doesn't really matter), and even with only 4 to 5 of them, they would swing! Also note that I am not looking for a sleeping scheme. But I would settle if you have any explicit scheme to handle resting contacts. That said, I would be more than happy if you have a way of treating it generally (as continuous collision, instead of explicitly as a special state). Ideas I have tried: Using simultaneous position based error correction as described in the paper in section 5.3.2, turned out to be worse than the current scheme. If you want to know the parameters I used: Hexagons, side 50 (pixels) gravity 2400 (pixels/sec^2) time-step 1/60 (sec) beta 0.1 restitution 0 to 0.2 coeff. of friction 0.2 PGS iteration 10 initial separation 10 (pixels) mass 1 (unit is irrelevant for now, i modified velocity directly<-impulse method) inertia 1/1000 Thanks in advance! I really appreciate any help from you guys!! :) EDIT In response to Cholesky's comment about warm starting the solver and Baumgarte: Oh right, I forgot to mention! I do save the contact history and the impulse determined in this time step to be used as initial guess in the next time step. As for the Baumgarte, here's what actually happens in the code. Collision is detected when the bodies' closest distance is less than SKIN, meaning they are actually still separated. If at this moment, I used the PGS solver without Baumgarte, restitution of 0 alone would be able to stop the bodies, separated by a distance of ~SKIN, in mid-air! So this isn't right, I want to have the bodies touching each other. So I turn on the Baumgarte, where its role is actually to pull the bodies together! Weird I know, a scheme intended to push the body apart becomes useful for the reverse. Also, I found that if I increase the number of iteration to 100, stacks become much more stable, though the program becomes so slow. UPDATE Since the stack swings left and right, could it be something is wrong with my friction model? Current friction constraint: relative_tangential_velocity = 0

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• A* algorithm very slow

  - by Amaranth

  I have an programming a RTS game (I use XNA with C#). The pathfinding is working fine, except that when it has a lot of node to search in, there is a lag period of one or two seconds, it happens mainly when there is no path to the target destination, since it that situation there is more nodes to explore. I have the same problem when the path is shorter but selected more than 3 units (can't take the same path since the selected units can be in different part of the map). private List<NodeInfo> FindPath(Unit u, NodeInfo start, NodeInfo end) { Map map = GameInfo.GetInstance().GameMap; _nearestToTarget = start; start.MoveCost = 0; Vector2 endPosition = map.getTileByPos(end.X, end.Y).Position; //getTileByPos simply gets the tile in a 2D array with the X and Y indexes start.EstimatedRemainingCost = (int)(endPosition - map.getTileByPos(start.X, start.Y).Position).Length(); start.Parent = null; List<NodeInfo> openedNodes = new List<NodeInfo>(); ; List<NodeInfo> closedNodes = new List<NodeInfo>(); Point[] movements = GetMovements(u.UnitType); openedNodes.Add(start); while (!closedNodes.Contains(end) && openedNodes.Count > 0) { //Loop in nodes to find lowest cost NodeInfo currentNode = FindLowestCostOpenedNode(openedNodes); openedNodes.Remove(currentNode); closedNodes.Add(currentNode); Vector2 previousMouvement; if (currentNode.Parent == null) { previousMouvement = ConvertRotationToDirectionVector(u.Rotation); } else { previousMouvement = map.getTileByPos(currentNode.X, currentNode.Y).Position - map.getTileByPos(currentNode.Parent.X, currentNode.Parent.Y).Position; previousMouvement.Normalize(); } //For each neighbor foreach (Point movement in movements) { Point exploredGridPos = new Point(currentNode.X + movement.X, currentNode.Y + movement.Y); //Checks if valid move and checks if not if closed nodes list if (ValidNavigableNode(u.UnitType, new Point(currentNode.X, currentNode.Y), exploredGridPos) && !closedNodes.Contains(_gridMap[exploredGridPos.Y, exploredGridPos.X])) { NodeInfo exploredNode = _gridMap[exploredGridPos.Y, exploredGridPos.X]; Tile.TileType exploredTerrain = map.getTileByPos(exploredGridPos.X, exploredGridPos.Y).TerrainType; if(openedNodes.Contains(exploredNode)) { int newCost = currentNode.MoveCost + GetMoveCost(previousMouvement, movement, exploredTerrain); if (newCost < exploredNode.MoveCost) { exploredNode.Parent = currentNode; exploredNode.MoveCost = newCost; //Find nearest tile to the target (in case doesn't find path to target) //Only compares the node to the current nearest FindNearest(exploredNode); } } else { exploredNode.Parent = currentNode; exploredNode.MoveCost = currentNode.MoveCost + GetMoveCost(previousMouvement, movement, exploredTerrain); Vector2 exploredNodeWorldPos = map.getTileByPos(exploredGridPos.X, exploredGridPos.Y).Position; exploredNode.EstimatedRemainingCost = (int)(endPosition - exploredNodeWorldPos).Length(); //Find nearest tile to the target (in case doesn't find path to target) //Only compares the node to the current nearest FindNearest(exploredNode); openedNodes.Add(exploredNode); } } } } return closedNodes; } After that, I simply check if the end node is contained in the returned nodes. If so, I add the end node and each parent until I reach the start. If not, I add the nearestToTarget and each parent until I reach the start. I added a condition before calling FindPath so that only one unit can call a find path each frame (60 frame per second), but it makes no difference. I thought maybe I could solve this by allowing the find path to run in background while the game continues to run correctly, even if it takes a few frame (it is currently sequential sonce it is called in the update() of the unit if there's a target location but no path), but I don't really know how... I also though about sorting my opened nodes list by cost so I don't have to loop them, but I don't know if that would have an effect on the performance... Would there be other solutions? P.S. In the code, when I get the Move Cost, I check if the unit has to turn to perform the move, and the terrain type, nothing hard to do.

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• IRP_MJ_WRITE latency up to 15 seconds

  - by racitup

  We have written an application that performs small (22kB) writes to multiple files at once (one thread performing asynchronous queued writes to multiple locations on behalf of other threads) on the same local volume (RAID1). 99.9% of the writes are low-latency but occasionally (maybe every minute or two) we get one or two huge latency writes (I have seen 10 seconds and above) without any real explanation. Platform: Win2003 Server with NTFS. Monitoring: Sysinternals Process Monitor (see link below) and our own application logging. We have tried multiple things to try and solve this that have been gleaned from a few websites, e.g.: Making the first part of file names unique to aid 8.3 name generation Writing files to multiple directories Changing Intel Disk Write Caching Windows File/Printer Sharing Minimize memory used Balance Maximize data throughput for file sharing Maximize data throughput for network applications System-Advanced-Performance-Advanced NtfsDisableLastAccessUpdate - use fsutil behavior set disablelastaccess 1 disable 8.3 name generation - use "fsutil behavior set disable8dot3 1" + restart Enable a large size file system cache Disable paging of the kernel code IO Page Lock Limit Turn Off (or On) the Indexing Service But nothing seems to make much difference. There's a whole host of things we haven't tried yet but we wondered if anyone had come across the same problem, a reason and a solution (programmatic or not)? We can reproduce the problem using IOMeter and a simple setup: Start IOMeter and remove all but the first worker thread in 'Topology' using the disconnect button. Select the Worker thread and put a cross in the box next to the disk you want to use in the Disk Targets tab and put '2000000' in Maximum Disk Size (NOTE: must have at least 1GB free space; sector size is 512 bytes) Next create a new access specification and add it to the worker thread: Transfer Request Size = 22kB 100% Sequential Percent of Access Spec = 100% Percent Read/Write = 100% Write Change Results Display Update Frequency to 5 seconds, Test Setup Run Time to 20 seconds and both 'Number of Workers to Spawn Automatically' settings to zero. Select the Worker Thread in the Topology panel and hit the Duplicate Worker button 59 times to create 60 threads with identical settings. Hit the 'Go' button (green flag) and monitor the Results tab. The 'Maximum I/O Response Time (ms)' always hits at least 3500 on our machine. Our machine isn't exactly slow (Xeon 8 core rack server with 4GB and onboard RAID). I'd be interested to see what other people get. We have a feeling it might be something to do with the NTFS filesystem (ours is currently 75% full of fragmented files) and we are going to try a few things around this principle. But it is also related to disk performance since we don't see it on a RAMDisk and it's not as severe on a RAID10 array. Any help is much appreciated. Richard Right-click and select 'Open Link in New Tab': ProcMon Result

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• networking tunnel adapter connections?

  - by Karthik Balaguru

  I understand that Tunnel Adapter LAN is for encapsulating IPv6 packets with an IPv4 header so that they can be sent across an IPv4 network. Few queries popped up in my mind based on this :- If i do 'ipconfig', Apart from ethernet adapter LAN details, I get a series of statments as below - Tunnel adapter Local Area Connection* 6 Tunnel adapter Local Area Connection* 7 Tunnel adapter Local Area Connection* 12 Tunnel adapter Local Area Connection* 13 Tunnel adapter Local Area Connection* 14 Tunnel adapter Local Area Connection* 15 Tunnel adapter Local Area Connection* 16 Except for the *16, all the other Tunnel Adapter Local Area Connections show Media Disconnected. Why is the numbering for the Tunnel adapter LAN not sequential? It is like 6, 7, 12, 13, 14, 15, 16. A strange numbering scheme! I tried to figure it out by thinking of some arithmetic series. But, it does not seem to fit in. There is a huge gap between 7 and 12. Any ideas? What is the need for so many Tunnel Adapter LAN connections? Can you tell me a scenario that requires all of those ? I did ipconfig /all to get more information. From the listing, I understand that: 16, 15, 14, 12 are Microsoft 6to4 Adapters 13, 6 are isatap Adapters 7 is Teredo Tunneling Pseudo-interface I understand that the above are for automatic tunneling so that the tunnel endpoints are determined automatically by the routing infrastructure. 6to4 is recommended by RFC3056 for automatic tunneling that uses protocol 41 for encapsulation. It is typically used when an end-user wants to connect to the IPv6 Internet using their existing IPv4 connection. Teredo is an automatic tunneling technique that uses UDP encapsulation across multiple NATs. That is, It is to grant IPv6 connectivity to nodes that are located behind IPv6-unaware NAT devices ISATAP treats the IPv4 network as a virtual IPv6 local link, with mappings from each IPv4 address to a link-local IPv6 address. That is to transmit IPv6 packets between dual-stack nodes on top of an IPv4 network. That is, to put in simple words, ISATAP is an intra-site mechanism, while the 6to4 and Teredo are for inter-site tunnelling mechanisms. It seems that Teredo should alone enabled by default in Vista, But my system does not show it to be enabled by default. Interestingly, it shows a 6to4 tunnel adapter (Tunnel adapter LAN connection 16) to be enabled by default? Any specific reasons for it? If i do ipconfig /all, why is only one Teredo present while four 6to4 are present ? I searched the internet for answers to the above queries, but I am unable to find clear answers.

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