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  • How to make natural-looking paths with A* on a grid?

    - by user11177
    I've been reading this: http://theory.stanford.edu/~amitp/GameProgramming/Heuristics.html But there are some things I don't understand, for example the article says to use something like this for pathfinding with diagonal movement: function heuristic(node) = dx = abs(node.x - goal.x) dy = abs(node.y - goal.y) return D * max(dx, dy) I don't know how do set D to get a natural looking path like in the article, I set D to the lowest cost between adjacent squares like it said, and I don't know what they meant by the stuff about the heuristic should be 4*D, that does not seem to change any thing. This is my heuristic function and move function: def heuristic(self, node, goal): D = 10 dx = abs(node.x - goal.x) dy = abs(node.y - goal.y) return D * max(dx, dy) def move_cost(self, current, node): cross = abs(current.x - node.x) == 1 and abs(current.y - node.y) == 1 return 19 if cross else 10 Result: The smooth sailing path we want to happen: The rest of my code: http://pastebin.com/TL2cEkeX

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  • Efficient Way to Draw Grids in XNA

    - by sm81095
    So I am working on a game right now, using Monogame as my framework, and it has come time to render my world. My world is made up of a grid (think Terraria but top-down instead of from the side), and it has multiple layers of grids in a single world. Knowing how inefficient it is to call SpriteBatch.Draw() a lot of times, I tried to implement a system where the tile would only be drawn if it wasn't hidden by the layers above it. The problem is, I'm getting worse performance by checking if it's hidden than when I just let everything draw even if it's not visible. So my question is: how to I efficiently check if a tile is hidden to cut down on the draw() calls? Here is my draw code for a single layer, drawing floors, and then the tiles (which act like walls): public void Draw(GameTime gameTime) { int drawAmt = 0; int width = Tile.TILE_DIM; int startX = (int)_parent.XOffset; int startY = (int)_parent.YOffset; //Gets the starting tiles and the dimensions to draw tiles, so only onscreen tiles are drawn, allowing for the drawing of large worlds int tileDrawWidth = ((CIGame.Instance.Graphics.PreferredBackBufferWidth / width) + 4); int tileDrawHeight = ((CIGame.Instance.Graphics.PreferredBackBufferHeight / width) + 4); int tileStartX = (int)MathHelper.Clamp((-startX / width) - 2, 0, this.Width); int tileStartY = (int)MathHelper.Clamp((-startY / width) - 2, 0, this.Height); #region Draw Floors and Tiles CIGame.Instance.GraphicsDevice.SetRenderTarget(_worldTarget); CIGame.Instance.GraphicsDevice.Clear(Color.Black); CIGame.Instance.SpriteBatch.Begin(); //Draw floors for (int x = tileStartX; x < (int)MathHelper.Clamp(tileStartX + tileDrawWidth, 0, this.Width); x++) { for (int y = tileStartY; y < (int)MathHelper.Clamp(tileStartY + tileDrawHeight, 0, this.Height); y++) { //Check if this tile is hidden by layer above it bool visible = true; for (int i = this.LayerNumber; i <= _parent.ActiveLayer; i++) { if (this.LayerNumber != (_parent.Layers - 1) && (_parent.GetTileAt(x, y, i + 1).Opacity >= 1.0f || _parent.GetFloorAt(x, y, i + 1).Opacity >= 1.0f)) { visible = false; break; } } //Only draw if visible under the tile above it if (visible && this.GetTileAt(x, y).Opacity < 1.0f) { Texture2D tex = WorldTextureManager.GetFloorTexture((Floor)_floors[x, y]); Rectangle source = WorldTextureManager.GetSourceForIndex(((Floor)_floors[x, y]).GetTextureIndexFromSurroundings(x, y, this), tex); Rectangle draw = new Rectangle(startX + x * width, startY + y * width, width, width); CIGame.Instance.SpriteBatch.Draw(tex, draw, source, Color.White * ((Floor)_floors[x, y]).Opacity); drawAmt++; } } } //Draw tiles for (int x = tileStartX; x < (int)MathHelper.Clamp(tileStartX + tileDrawWidth, 0, this.Width); x++) { for (int y = tileStartY; y < (int)MathHelper.Clamp(tileStartY + tileDrawHeight, 0, this.Height); y++) { //Check if this tile is hidden by layers above it bool visible = true; for (int i = this.LayerNumber; i <= _parent.ActiveLayer; i++) { if (this.LayerNumber != (_parent.Layers - 1) && (_parent.GetTileAt(x, y, i + 1).Opacity >= 1.0f || _parent.GetFloorAt(x, y, i + 1).Opacity >= 1.0f)) { visible = false; break; } } if (visible) { Texture2D tex = WorldTextureManager.GetTileTexture((Tile)_tiles[x, y]); Rectangle source = WorldTextureManager.GetSourceForIndex(((Tile)_tiles[x, y]).GetTextureIndexFromSurroundings(x, y, this), tex); Rectangle draw = new Rectangle(startX + x * width, startY + y * width, width, width); CIGame.Instance.SpriteBatch.Draw(tex, draw, source, Color.White * ((Tile)_tiles[x, y]).Opacity); drawAmt++; } } } CIGame.Instance.SpriteBatch.End(); Console.WriteLine(drawAmt); CIGame.Instance.GraphicsDevice.SetRenderTarget(null); //TODO: Change to new rendertarget instead of null #endregion } So I was wondering if this is an efficient way, but I'm going about it wrongly, or if there is a different, more efficient way to check if the tiles are hidden. EDIT: For example of how much it affects performance: using a world with three layers, allowing everything to draw no matter what gives me 60FPS, but checking if its visible with all of the layers above it gives me only 20FPS, while checking only the layer immediately above it gives me a fluctuating FPS between 30 and 40FPS.

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  • How is Basic Physics applied in CS/SE?

    - by Wulf
    What basic physics principles do software engineers and/or computer scientists use to help solve specific or common problems? The first one that came to my head was creating a Physics engine for a game; physics is involved, as it requires knowledge of: Forces and Motion: Kinematics, Dynamics, Circular Motion However, I need another example, but haven't come across one that involves basic physics. Please consider the following basic physics (grade 12 level) concepts: Energy and Momentum: Work and Energy, Momentum and Collisions, Gravitational and Celestial Mechanics Electric, Gravitational & Magnetic Field: Electric Charges and Electric Field, Magnetic Fields and Electomagnetism The Wave Nature of Light: Waves and Light, Wave Effects of Light Matter-Energy Interface: Einstein’s Special Theory of Relativity, Waves, Photons and Matter, Radioactivity and Elementary Particles I will be happy with any response; Keywords for google, names of methods like raycasting, etc.

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  • Overlay scrollbars disabled on upgrade - how to reenable?

    - by Aibara Iduas
    When I upgraded from Natty to Oneiric and then immediately to Precise, for some reason the overlay scrollbars stopped appearing. They were enabled and worked just fine in Natty, and are still enabled in theory. I've purged and reinstalled these packages: overlay-scrollbar, liboverlay-scrollbar-0.2-0, and liboverlay-scrollbar3-0.2-0. That did nothing. I also tried using both Ubuntu Tweak and Unsettings, but both showed that overlay scrollbars were turned on (and turning the settings off and back on again did nothing either). Any ideas how to get them back? Thanks!

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  • Advice: should I focus on PHP + MySQL, or split my time for more JS and CSS? [closed]

    - by fakaff
    I started learning web development about three months ago (in between working my regular job), and I'm finally starting to get some vague, distant notion of understanding. I find the server-side stuff the most interesting; though I've not gone anywhere near Apache quite yet, which I assume will be necessary at some point. As cool as toying around with visuals and UI is, programming and database stuff inspires me with new ideas and possibilities every minute (I've even bought, on a whim, a wonderfully dry bunch of books on database theory and relational algebra). And whatever CSS or Javascript tutorial I'm doing, it often feels like a distraction from the PHP/MySQL stuff I'd rather be playing with. For someone like me who's just starting out, which is the most advisable course of action? (in terms of being marketable as a programmer): To focus on PHP and SQL stuff exclusively, and only once I master those to diversify my skills. To first learn all three (PHP/MySQL, Javascript, CSS and design) and only once I'm fluent in all three focus on PHP and databases?

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  • test coverage reality

    - by iPhoneDeveloper
    I am NOT doing test driven development and I write my test classes after the actual code is written. In my current project I have a test coverage of(Line coverage) %70 for 3000 lines of Java code.(Using JUnit, Mockito and Sonar for testing) But while I feel actually I am not covering and catching %70 of the problems that can occur. So my question is in theory is that possible to have a %100 Line coverage but in reality it is meaningless because of low quality of the test code and maybe a %40 well written test code is much better than a bad %100 coverage? or we can always say line coverage more or less gives the percentage of all covered issues?

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  • 2D fighting bounding boxes

    - by user36420
    I'm prototyping a 2D platformer/brawler game for uni and I'm having some trouble with creating collision/bounding boxes. This is most likely going to end up on a Vita so I do have some library constraints as well as performance implications. None of this has yet been implemented but is all theory. My idea was to have the artist create a sprite sheet for the character animation and then a second identical sprite sheet with the corresponding collisions in a solid colour (e.g green for where the character can be hit and red for dealing damage, near the foot if kicking etc.) With this, I would then parse the collision sheet and generate the various collisions required storing them in the character model. This is the point I feel would be most inefficient. While I think this is a possible solution, I was wondering if there was a more standard way of doing this or a more efficient way as I feel this would have severe performance problems.

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  • Algorithm development in jobs

    - by dbeacham
    I have a mathematics background but also consider career in some form of software development. In particular I'm interested in finding out what sort of industries are most likely to have more algorithm development/mathematical and logical problem solving slant rather than pure application development etc. Obviously, I'm assuming that some subset of the canonical data structures and associated algorithms (trees, lists, hash tables, sets, maps with search, insert, traversals etc.) are mostly going to be present in software development. However, where am I more likely to encounter problems of more discrete maths nature (combinatorial, graph theory, sets, strings, ...) explicitly or more likely in disguise. Any pointers much appreciated (including possible open source projects that I could use for my further search for applications and also possibly contribute to).

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  • is it possible to get a programming job in the bay area?

    - by user475119
    Is it my perception or is it reality that it is harder to get software development work in Silicon Valley, than in other population centers? My theory is that some of the best and brightest (and youngest) are all here. All working for the top tech companies. And, little ol' me, over 40, math degree (not at Standford or Berkeley), ok at algorithms, and with many skills with many programming tools and concepts, but not published, and not top my class has a bit of a tough time competing. (I'm a Python programmer, by the way.) Thanks

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  • Is it possible to work with a dedicated server in XNA?

    - by Jake
    Hi I want to release my XNA game to the XBOX platform, but I'm worried about the networking limitations. Basically, I want to have a dedicated (authoritative) server, but it sounds like that is not possible. Which is why I'm wondering about: Using port 80 web calls to php-driven database Using an xbox as a master-server (is that possible?) I like the sound of #1, because I could write my own application to run on the xbox, and I would assume other users could connect to it similar to the p2p architecture. Anyone able to expand on theory #2 above? or #1 as worst-case scenario?

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  • New WebKit tests

    I have updated the WebKit comparison table with data from Safari 5, Chrome 5, and Android 2.1. Improvements throughout!The top five WebKit browsers according to these tests are now: Chrome 5 Safari 5 Safari 4 Samsung WebKit (on bada) Android 2.1Interesting findings: Chrome and Android now support localStorage (Safari already did). Chrome and Android now support geolocation. Safari does in theory, but it doesn’t give the actual coordinates, making the whole exercise a bit pointless. Chrome and Android...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Stairway to T-SQL DML Level 4: The Mathematics of SQL: Part 1

    A relational database contains tables that relate to each other by key values. When querying data from these related tables you may choose to select data from a single table or many tables. If you select data from many tables, you normally join those tables together using specified join criteria. The concepts of selecting data from tables and joining tables together is all about managing and manipulating sets of data. In Level 4 of this Stairway we will explore the concepts of set theory and mathematical operators to join, merge, and return data from multiple SQL Server tables. Get Smart with SQL Backup Pro Powerful centralised management, encryption and more.SQL Backup Pro was the smartest kid at school Discover why.

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  • CSS hover behavior inconsistent on desktop/mobile devices [migrated]

    - by tbart
    I have a strange problem: This page looks good on desktop browsers, but the hovering effect does not seem to work correctly on at least my CM7 Android 2.3.7 device. I know hovering is not supposed to work on touch displays as it does with a mouse, but I'd like to have touch feedback, i.e. the highlight color should show once the user has tapped a menu item. This does work when the link is just a href="#" but it does not when it is a real link. I tried all sorts of stuff as you can see, to no avail. If you go back in the browser history after having tapped a real link, the item is highlighted, so the browser understands the CSS I am throwing at it. However, the javascript alert makes it clear that it only seems to interpret the link opening action and does not care about the color changing stuff. Weird that is. Workarounds welcome, preferable without javascript, but if it has to be JS, then go ahead! either go here: http://orpheus.co.at/hoverprob and Use the source, Luke! or see it here in all its glory: <html> <head> <meta name="viewport" content="width=320"> <style> #nav, #nav ul { width: 100%; float: left; list-style: none; line-height: 1; background: #fff; font-weight: bold; padding: 0; margin: 0 0 5px 0; } #nav a { display: block; color: #001834; text-decoration: none; padding: 5px 7px; } #nav li { float: left; padding: 0; width: 33%; } #nav li ul { position: absolute; left: -9999px; height: auto; margin: 0; opacity: .95; width: 100%; } #nav li a { text-align: center; height: 20px; line-height: 20px; } #nav li ul li a { text-align: left; } #nav li ul li { float: none; /* width: 316px; */ width: 100%; } #nav li:hover ul ul, #nav li:hover ul ul ul, #nav li.sfhover ul ul, #nav li.sfhover ul ul ul { left: -9999px; } #nav li:hover ul, #nav li li:hover ul, #nav li li li:hover ul, #nav li.sfhover ul, #nav li li.sfhover ul, #nav li li li.sfhover ul { left: 0; } #nav li.educate { background: #FFF0B8; /* background: #FF0000; */ /* border-radius: 5px; */ border: 5px; } #nav li.educate:hover { background: #FFCE00; /* border-radius: 5px; */ } </style> </head> <body> <div id="mobMenu"> <ul id="nav" class="nav"> <li class="educate"><a href="#">menu</a> <ul class="educate"> <li class="educate"><a href="#">href=&quot#&quot;, works</a></li> <!--(+emtpy onmouseover for iPose devices)--> <li class="educate"><a onmouseover="" href="index.html">does not work, real link</a></li> <li class="educate" id="bla"><a onmousedown="document.getElementById('bla').style.backgroundColor='Blue'; alert('Done');document.location='index.html';" href="#">JS, not interpreted in corr order</a></li> </ul> </li> </div> </body>

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  • Attributes and Behaviours in game object design

    - by Brukwa
    Recently I have read interesting slides about game object design written by Marcin Chady Theory and Practice of the Game Object Component Architecture. I have prototyped quick sample that utilize all Attributes\Behaviour idea with some sample data. Now I have faced a little problem when I added a RenderingSystem to my prototype application. I have created an object with RenderBehaviour which listens for messages (OnMessage function) like MovedObject in order to mark them as invalid and in OnUpdate pass I am inserting a new renderable object to rederer queue. I have noticed that rendering updates should be the last thing made in single frame and this causes RenderBehaviour to depend on any other Behaviour that changes object position (i.ex. PhysicsSystem and PhysicsBehaviour). I am not even sure if I am doing this the way it should be. Do you have any clues that might put me on the right track?

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  • What are good/fast methods to pull data from a database using JavaScript?

    - by Yatrix
    I'm pretty new to web technologies and I am creating a filter control that will have cascading controls. We are doing a lot of this through JavaScript and are debating the best route to take to the database. HTTPHandlers, WebServices and Ajax are all being considered (or a combination of them). We want to be able to handle a million rows in theory, so it has to be scalable to at that. We are going through JavaScript as our page must not do post-backs, if your'e wondering. I'm asking from an architectural standpoint, but will take any useful information. Links, control suggestions - anything you have, I'll happily listen to.

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  • How can I perform a masked erase in SDL2?

    - by Kvisle
    I'm trying to implement some shadow/lighting effects in my 2D-project, and I've concluded that if there is an easy way to perform a masked erase on an SDL_Texture, it would make the drawing operations quite cheap. Let's say I have a texture of the part of the level where light is not meant to be rendered. I also have a texture with my "light map"; I want to use this to just draw omni lights from my light sources. Then I want to use the first image to 'subtract' the portions of the light map that are not to be rendered on the final scene. Then I draw my "light map" texture on top of my scene, with additive blending enabled. This sounds like a good theory in my head, but I can't see any functions in the SDL2 API that let me do masked erase from a texture. Am I overlooking something? Does anything like this exist?

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  • Two Values Enter, One Value Leaves

    - by Bunch
    This is a fairly easy way to compare values for two different controls. In this example a user needs to enter in a street address and zip code OR pick a county. After that the application will display location(s) based on the value. The application only wants a specific street/zip combination or a county, not both. This code shows how to check for that on an ASP.Net page using some JavaScript. The control code: <table>     <tr>         <td>             <label style="color: Red;">Required Fields</label>         </td>         <td style="width: 300px;">             <label style="color: Red; font-weight: bold;" id="reqAlert" ></label>         </td>     </tr>     <tr>         <td>             <asp:Label ID="Label3" runat="server" Text="Street Address"></asp:Label>         </td>         <td style="width: 200px;">             <input id="Street" type="text" style="width: 200px;" />         </td>     </tr>      <tr>         <td>             <asp:Label ID="Label5" runat="server" Text="Zip Code"></asp:Label>             &nbsp;         </td>         <td style="width: 200px;">             <input id="Zip" type="text" style="width: 200px;"/>         </td>     </tr>     <tr>         <td>             <label style="color: Red; font-size: large;">-- OR --</label>         </td>     </tr>     <tr>         <td>             <asp:Label ID="Label2" runat="server" Text="County"></asp:Label>         </td>         <td style="width: 200px;">             <asp:DropDownList ID="ddlCounty" runat="server">                 <asp:ListItem Value="0" Text="" />                 <asp:ListItem Value="1" Text="County A" />                 <asp:ListItem Value="2" Text="County B" />                 <asp:ListItem Value="3" Text="County C" />                                </asp:DropDownList>         </td>     </tr> </table> <input id="btnMapSearch" type="button" value="Search" onclick="requiredVal()" class="actionButton" /> The onclick for the button runs the requiredVal javascript function. That is where the checks take place. If only one item (street/zip or county) has been entered the application will carry on with it’s locateAddr function; otherwise it will show an error message in the label reqAlert. The javascript: function requiredVal() {     var street = document.getElementById("Street").value;     var zip = document.getElementById("Zip").value;     var countyDdl = document.getElementById("ctl00_Content_ddlCounty");     var county = countyDdl.options[countyDdl.selectedIndex].text;     var reqAlert = document.getElementById("reqAlert");     reqAlert.innerHTML = '';   //clears out any previous messages     if (street != '' || zip != '') {         if (county != '') {             reqAlert.innerHTML = 'Please select only one required option';  //values for both were entered         }         else {             locateAddr();         }     }     else if (street == '' && zip == '' && county == '') {         reqAlert.innerHTML = 'Please select a required option';  //no values entered     }     else {         locateAddr();     } } Technorati Tags: ASP.Net,JavaScript

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  • 12.04 Software "RAID 0" on desktop replacement, 2 HDD?

    - by gregzeng
    Hardware: HP Pavilion DV7 notebook: 8GB DDR3, 2x 750GB SATA2 HDD, I7 c+ Radeon GPU, eSATA, Bluray, etc. Currently multiboot with Win7-64 + choice of 5 'buntu-64. Prefer Xubuntu-64-alternate, but not able to install software RAID-0 at the last active partition on both HDDs. Tried many types: real boot partition, etc. All my Linux op sys boot successfully from the extended partitions on both drives, but without RAID of any kind. Theory - yes. But has anyone really succeeded with 12.04 software RAID-0?

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  • How do I connect the seams between my terrain?

    - by gnomgrol
    I'm using c++ and D3D11 and I'm trying to create a (pretty) large terrain, lets say 4096x4096, maybe larger. I've got the basics of terrain creation and already split it up into chunks. But, when I'm rendering them (every chunk has its own vertex and index buffer, as well as its own heightmap), there are still little pieces missing between them. I read a lot about LOD(Level Of Detail) and GMM(Geometry Mipmap), but I can't really implement the theory I read. At the moment, it looks like this: I could really use some help, everything is welcome. If you have some good tutorials on any of this, please share them.

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  • Difference between '\n' and '\r\n'

    - by sukhbir
    Yes yes, I am aware that '\n' writes a newline in UNIX while for Windows there is the two character sequence: '\r\n'. All this is very nice in theory, but my question is why? Why the carriage return character is extra in Windows? If UNIX can do it in \n why does it take Windows two characters to do this? I am reading David Beazley's Python book and he says: For example, on Windows, writing the character '\n' actually outputs the two- character sequence '\r\n' (and when reading the file back, '\r\n' is translated back into a single '\n' character). Why the extra effort? I will be honest. I have known the difference for a long time but have never bothered to ask WHY. I hope that is answered today. Thanks for your time.

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  • Storing Projects on Google Drive (Cloud)

    - by JamesKraw
    I've started using Google Drive for my cloud needs and backing up pretty much everything. I've got the app installed so it auto-sync's all my content in most things. My question is this, I am currently coding for iOS (although this applies to any coding project) and am split on storing my project files on Google Drive while using sync. My theory is that if I did use it, I'd never have to worry about system crashes or lost code before backups, but if I do use it it will be sync'ing a-lot and I thought there might be problems with it detecting changes and trying to sync for example half way through compiling. Bandwidth isn't an issue as I have fast connection and unlimited monthly allowance. Has anyone ever used this, or similar cloud-based sync'ing (dropbox etc) for this and knows whether it works or not or whether there are any potential problems etc.

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  • What is the difference from the push and pull development models?

    - by michelpm
    I was reading Extreme Programming Explained, Second Edition and in the chapter 11 "The Theory of Constraints" the authors talk about the old and obsolete "push" development model and the XP way, the "pull" development model. It looks like a quite important concept, but it takes only a very small paragraph and two images that are mere illustrations of the "waterfall" and iterative process, nothing specific about these models except by the image caption. I searched and it doesn't go any further about it in the rest of the book. I couldn't find any further explanations or discussions about it in the Internet either. If the only difference about those is that one is "waterfall" and the other is iterative, them why push and why pull? Does anyone understand what is really the difference between those two and give some good examples?

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  • Start programming at 26? [closed]

    - by user663250
    Possible Duplicate: Is it too late to start programming? Hi, i am 26 and have a mathematics degree (specialized in logic and set theory). I feel i need a change and wanted to start programming, i have some experience (low-midd) with python and lisp, right now i am starting with c++ (stroustrup book)... My problem is that i am not sure where is a good place to start getting real experience (jobs, projects, etc... to keep motivation up), how much do i need to know to start looking for this and what other things i need to know to be a better programmer... My areas of interest are AI and gaming. But right now i just want to learn all i need or more...

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  • Inheritance Mapping Strategies with Entity Framework Code First CTP5: Part 3 – Table per Concrete Type (TPC) and Choosing Strategy Guidelines

    - by mortezam
    This is the third (and last) post in a series that explains different approaches to map an inheritance hierarchy with EF Code First. I've described these strategies in previous posts: Part 1 – Table per Hierarchy (TPH) Part 2 – Table per Type (TPT)In today’s blog post I am going to discuss Table per Concrete Type (TPC) which completes the inheritance mapping strategies supported by EF Code First. At the end of this post I will provide some guidelines to choose an inheritance strategy mainly based on what we've learned in this series. TPC and Entity Framework in the Past Table per Concrete type is somehow the simplest approach suggested, yet using TPC with EF is one of those concepts that has not been covered very well so far and I've seen in some resources that it was even discouraged. The reason for that is just because Entity Data Model Designer in VS2010 doesn't support TPC (even though the EF runtime does). That basically means if you are following EF's Database-First or Model-First approaches then configuring TPC requires manually writing XML in the EDMX file which is not considered to be a fun practice. Well, no more. You'll see that with Code First, creating TPC is perfectly possible with fluent API just like other strategies and you don't need to avoid TPC due to the lack of designer support as you would probably do in other EF approaches. Table per Concrete Type (TPC)In Table per Concrete type (aka Table per Concrete class) we use exactly one table for each (nonabstract) class. All properties of a class, including inherited properties, can be mapped to columns of this table, as shown in the following figure: As you can see, the SQL schema is not aware of the inheritance; effectively, we’ve mapped two unrelated tables to a more expressive class structure. If the base class was concrete, then an additional table would be needed to hold instances of that class. I have to emphasize that there is no relationship between the database tables, except for the fact that they share some similar columns. TPC Implementation in Code First Just like the TPT implementation, we need to specify a separate table for each of the subclasses. We also need to tell Code First that we want all of the inherited properties to be mapped as part of this table. In CTP5, there is a new helper method on EntityMappingConfiguration class called MapInheritedProperties that exactly does this for us. Here is the complete object model as well as the fluent API to create a TPC mapping: public abstract class BillingDetail {     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } }          public class BankAccount : BillingDetail {     public string BankName { get; set; }     public string Swift { get; set; } }          public class CreditCard : BillingDetail {     public int CardType { get; set; }     public string ExpiryMonth { get; set; }     public string ExpiryYear { get; set; } }      public class InheritanceMappingContext : DbContext {     public DbSet<BillingDetail> BillingDetails { get; set; }              protected override void OnModelCreating(ModelBuilder modelBuilder)     {         modelBuilder.Entity<BankAccount>().Map(m =>         {             m.MapInheritedProperties();             m.ToTable("BankAccounts");         });         modelBuilder.Entity<CreditCard>().Map(m =>         {             m.MapInheritedProperties();             m.ToTable("CreditCards");         });                 } } The Importance of EntityMappingConfiguration ClassAs a side note, it worth mentioning that EntityMappingConfiguration class turns out to be a key type for inheritance mapping in Code First. Here is an snapshot of this class: namespace System.Data.Entity.ModelConfiguration.Configuration.Mapping {     public class EntityMappingConfiguration<TEntityType> where TEntityType : class     {         public ValueConditionConfiguration Requires(string discriminator);         public void ToTable(string tableName);         public void MapInheritedProperties();     } } As you have seen so far, we used its Requires method to customize TPH. We also used its ToTable method to create a TPT and now we are using its MapInheritedProperties along with ToTable method to create our TPC mapping. TPC Configuration is Not Done Yet!We are not quite done with our TPC configuration and there is more into this story even though the fluent API we saw perfectly created a TPC mapping for us in the database. To see why, let's start working with our object model. For example, the following code creates two new objects of BankAccount and CreditCard types and tries to add them to the database: using (var context = new InheritanceMappingContext()) {     BankAccount bankAccount = new BankAccount();     CreditCard creditCard = new CreditCard() { CardType = 1 };                      context.BillingDetails.Add(bankAccount);     context.BillingDetails.Add(creditCard);     context.SaveChanges(); } Running this code throws an InvalidOperationException with this message: The changes to the database were committed successfully, but an error occurred while updating the object context. The ObjectContext might be in an inconsistent state. Inner exception message: AcceptChanges cannot continue because the object's key values conflict with another object in the ObjectStateManager. Make sure that the key values are unique before calling AcceptChanges. The reason we got this exception is because DbContext.SaveChanges() internally invokes SaveChanges method of its internal ObjectContext. ObjectContext's SaveChanges method on its turn by default calls AcceptAllChanges after it has performed the database modifications. AcceptAllChanges method merely iterates over all entries in ObjectStateManager and invokes AcceptChanges on each of them. Since the entities are in Added state, AcceptChanges method replaces their temporary EntityKey with a regular EntityKey based on the primary key values (i.e. BillingDetailId) that come back from the database and that's where the problem occurs since both the entities have been assigned the same value for their primary key by the database (i.e. on both BillingDetailId = 1) and the problem is that ObjectStateManager cannot track objects of the same type (i.e. BillingDetail) with the same EntityKey value hence it throws. If you take a closer look at the TPC's SQL schema above, you'll see why the database generated the same values for the primary keys: the BillingDetailId column in both BankAccounts and CreditCards table has been marked as identity. How to Solve The Identity Problem in TPC As you saw, using SQL Server’s int identity columns doesn't work very well together with TPC since there will be duplicate entity keys when inserting in subclasses tables with all having the same identity seed. Therefore, to solve this, either a spread seed (where each table has its own initial seed value) will be needed, or a mechanism other than SQL Server’s int identity should be used. Some other RDBMSes have other mechanisms allowing a sequence (identity) to be shared by multiple tables, and something similar can be achieved with GUID keys in SQL Server. While using GUID keys, or int identity keys with different starting seeds will solve the problem but yet another solution would be to completely switch off identity on the primary key property. As a result, we need to take the responsibility of providing unique keys when inserting records to the database. We will go with this solution since it works regardless of which database engine is used. Switching Off Identity in Code First We can switch off identity simply by placing DatabaseGenerated attribute on the primary key property and pass DatabaseGenerationOption.None to its constructor. DatabaseGenerated attribute is a new data annotation which has been added to System.ComponentModel.DataAnnotations namespace in CTP5: public abstract class BillingDetail {     [DatabaseGenerated(DatabaseGenerationOption.None)]     public int BillingDetailId { get; set; }     public string Owner { get; set; }     public string Number { get; set; } } As always, we can achieve the same result by using fluent API, if you prefer that: modelBuilder.Entity<BillingDetail>()             .Property(p => p.BillingDetailId)             .HasDatabaseGenerationOption(DatabaseGenerationOption.None); Working With The Object Model Our TPC mapping is ready and we can try adding new records to the database. But, like I said, now we need to take care of providing unique keys when creating new objects: using (var context = new InheritanceMappingContext()) {     BankAccount bankAccount = new BankAccount()      {          BillingDetailId = 1                          };     CreditCard creditCard = new CreditCard()      {          BillingDetailId = 2,         CardType = 1     };                      context.BillingDetails.Add(bankAccount);     context.BillingDetails.Add(creditCard);     context.SaveChanges(); } Polymorphic Associations with TPC is Problematic The main problem with this approach is that it doesn’t support Polymorphic Associations very well. After all, in the database, associations are represented as foreign key relationships and in TPC, the subclasses are all mapped to different tables so a polymorphic association to their base class (abstract BillingDetail in our example) cannot be represented as a simple foreign key relationship. For example, consider the the domain model we introduced here where User has a polymorphic association with BillingDetail. This would be problematic in our TPC Schema, because if User has a many-to-one relationship with BillingDetail, the Users table would need a single foreign key column, which would have to refer both concrete subclass tables. This isn’t possible with regular foreign key constraints. Schema Evolution with TPC is Complex A further conceptual problem with this mapping strategy is that several different columns, of different tables, share exactly the same semantics. This makes schema evolution more complex. For example, a change to a base class property results in changes to multiple columns. It also makes it much more difficult to implement database integrity constraints that apply to all subclasses. Generated SQLLet's examine SQL output for polymorphic queries in TPC mapping. For example, consider this polymorphic query for all BillingDetails and the resulting SQL statements that being executed in the database: var query = from b in context.BillingDetails select b; Just like the SQL query generated by TPT mapping, the CASE statements that you see in the beginning of the query is merely to ensure columns that are irrelevant for a particular row have NULL values in the returning flattened table. (e.g. BankName for a row that represents a CreditCard type). TPC's SQL Queries are Union Based As you can see in the above screenshot, the first SELECT uses a FROM-clause subquery (which is selected with a red rectangle) to retrieve all instances of BillingDetails from all concrete class tables. The tables are combined with a UNION operator, and a literal (in this case, 0 and 1) is inserted into the intermediate result; (look at the lines highlighted in yellow.) EF reads this to instantiate the correct class given the data from a particular row. A union requires that the queries that are combined, project over the same columns; hence, EF has to pad and fill up nonexistent columns with NULL. This query will really perform well since here we can let the database optimizer find the best execution plan to combine rows from several tables. There is also no Joins involved so it has a better performance than the SQL queries generated by TPT where a Join is required between the base and subclasses tables. Choosing Strategy GuidelinesBefore we get into this discussion, I want to emphasize that there is no one single "best strategy fits all scenarios" exists. As you saw, each of the approaches have their own advantages and drawbacks. Here are some rules of thumb to identify the best strategy in a particular scenario: If you don’t require polymorphic associations or queries, lean toward TPC—in other words, if you never or rarely query for BillingDetails and you have no class that has an association to BillingDetail base class. I recommend TPC (only) for the top level of your class hierarchy, where polymorphism isn’t usually required, and when modification of the base class in the future is unlikely. If you do require polymorphic associations or queries, and subclasses declare relatively few properties (particularly if the main difference between subclasses is in their behavior), lean toward TPH. Your goal is to minimize the number of nullable columns and to convince yourself (and your DBA) that a denormalized schema won’t create problems in the long run. If you do require polymorphic associations or queries, and subclasses declare many properties (subclasses differ mainly by the data they hold), lean toward TPT. Or, depending on the width and depth of your inheritance hierarchy and the possible cost of joins versus unions, use TPC. By default, choose TPH only for simple problems. For more complex cases (or when you’re overruled by a data modeler insisting on the importance of nullability constraints and normalization), you should consider the TPT strategy. But at that point, ask yourself whether it may not be better to remodel inheritance as delegation in the object model (delegation is a way of making composition as powerful for reuse as inheritance). Complex inheritance is often best avoided for all sorts of reasons unrelated to persistence or ORM. EF acts as a buffer between the domain and relational models, but that doesn’t mean you can ignore persistence concerns when designing your classes. SummaryIn this series, we focused on one of the main structural aspect of the object/relational paradigm mismatch which is inheritance and discussed how EF solve this problem as an ORM solution. We learned about the three well-known inheritance mapping strategies and their implementations in EF Code First. Hopefully it gives you a better insight about the mapping of inheritance hierarchies as well as choosing the best strategy for your particular scenario. Happy New Year and Happy Code-Firsting! References ADO.NET team blog Java Persistence with Hibernate book a { color: #5A99FF; } a:visited { color: #5A99FF; } .title { padding-bottom: 5px; font-family: Segoe UI; font-size: 11pt; font-weight: bold; padding-top: 15px; } .code, .typeName { font-family: consolas; } .typeName { color: #2b91af; } .padTop5 { padding-top: 5px; } .padTop10 { padding-top: 10px; } .exception { background-color: #f0f0f0; font-style: italic; padding-bottom: 5px; padding-left: 5px; padding-top: 5px; padding-right: 5px; }

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  • Enterprise Process Maps: A Process Picture worth a Million Words

    - by raul.goycoolea
    p { margin-bottom: 0.08in; }h1 { margin-top: 0.33in; margin-bottom: 0in; color: rgb(54, 95, 145); page-break-inside: avoid; }h1.western { font-family: "Cambria",serif; font-size: 14pt; }h1.cjk { font-family: "DejaVu Sans"; font-size: 14pt; }h1.ctl { font-size: 14pt; } Getting Started with Business Transformations A well-known proverb states that "A picture is worth a thousand words." In relation to Business Process Management (BPM), a credible analyst might have a few questions. What if the picture was taken from some particular angle, like directly overhead? What if it was taken from only an inch away or a mile away? What if the photographer did not focus the camera correctly? Does the value of the picture depend on who is looking at it? Enterprise Process Maps are analogous in this sense of relative value. Every BPM project (holistic BPM kick-off, enterprise system implementation, Service-oriented Architecture, business process transformation, corporate performance management, etc.) should be begin with a clear understanding of the business environment, from the biggest picture representations down to the lowest level required or desired for the particular project type, scope and objectives. The Enterprise Process Map serves as an entry point for the process architecture and is defined: the single highest level of process mapping for an organization. It is constructed and evaluated during the Strategy Phase of the Business Process Management Lifecycle. (see Figure 1) Fig. 1: Business Process Management Lifecycle Many organizations view such maps as visual abstractions, constructed for the single purpose of process categorization. This, in turn, results in a lesser focus on the inherent intricacies of the Enterprise Process view, which are explored in the course of this paper. With the main focus of a large scale process documentation effort usually underlying an ERP or other system implementation, it is common for the work to be driven by the desire to "get to the details," and to the type of modeling that will derive near-term tangible results. For instance, a project in American Pharmaceutical Company X is driven by the Director of IT. With 120+ systems in place, and a lack of standardized processes across the United States, he and the VP of IT have decided to embark on a long-term ERP implementation. At the forethought of both are questions, such as: How does my application architecture map to the business? What are each application's functionalities, and where do the business processes utilize them? Where can we retire legacy systems? Well-developed BPM methodologies prescribe numerous model types to capture such information and allow for thorough analysis in these areas. Process to application maps, Event Driven Process Chains, etc. provide this level of detail and facilitate the completion of such project-specific questions. These models and such analysis are appropriately carried out at a relatively low level of process detail. (see figure 2) Fig. 2: The Level Concept, Generic Process HierarchySome of the questions remaining are ones of documentation longevity, the continuation of BPM practice in the organization, process governance and ownership, process transparency and clarity in business process objectives and strategy. The Level Concept in Brief Figure 2 shows a generic, four-level process hierarchy depicting the breakdown of a "Process Area" into progressively more detailed process classifications. The number of levels and the names of these levels are flexible, and can be fit to the standards of the organization's chosen terminology or any other chosen reference model that makes logical sense for both short and long term process description. It is at Level 1 (in this case the Process Area level), that the Enterprise Process Map is created. This map and its contained objects become the foundation for a top-down approach to subsequent mapping, object relationship development, and analysis of the organization's processes and its supporting infrastructure. Additionally, this picture serves as a communication device, at an executive level, describing the design of the business in its service to a customer. It seems, then, imperative that the process development effort, and this map, start off on the right foot. Figuring out just what that right foot is, however, is critical and trend-setting in an evolving organization. Key Considerations Enterprise Process Maps are usually not as living and breathing as other process maps. Just as it would be an extremely difficult task to change the foundation of the Sears Tower or a city plan for the entire city of Chicago, the Enterprise Process view of an organization usually remains unchanged once developed (unless, of course, an organization is at a stage where it is capable of true, high-level process innovation). Regardless, the Enterprise Process map is a key first step, and one that must be taken in a precise way. What makes this groundwork solid depends on not only the materials used to construct it (process areas), but also the layout plan and knowledge base of what will be built (the entire process architecture). It seems reasonable that care and consideration are required to create this critical high level map... but what are the important factors? Does the process modeler need to worry about how many process areas there are? About who is looking at it? Should he only use the color pink because it's his boss' favorite color? Interestingly, and perhaps surprisingly, these are all valid considerations that may just require a bit of structure. Below are Three Key Factors to consider when building an Enterprise Process Map: Company Strategic Focus Process Categorization: Customer is Core End-to-end versus Functional Processes Company Strategic Focus As mentioned above, the Enterprise Process Map is created during the Strategy Phase of the Business Process Management Lifecycle. From Oracle Business Process Management methodology for business transformation, it is apparent that business processes exist for the purpose of achieving the strategic objectives of an organization. In a prescribed, top-down approach to process development, it must be ensured that each process fulfills its objectives, and in an aggregated manner, drives fulfillment of the strategic objectives of the company, whether for particular business segments or in a broader sense. This is a crucial point, as the strategic messages of the company must therefore resound in its process maps, in particular one that spans the processes of the complete business: the Enterprise Process Map. One simple example from Company X is shown below (see figure 3). Fig. 3: Company X Enterprise Process Map In reviewing Company X's Enterprise Process Map, one can immediately begin to understand the general strategic mindset of the organization. It shows that Company X is focused on its customers, defining 10 of its process areas belonging to customer-focused categories. Additionally, the organization views these end-customer-oriented process areas as part of customer-fulfilling value chains, while support process areas do not provide as much contiguous value. However, by including both support and strategic process categorizations, it becomes apparent that all processes are considered vital to the success of the customer-oriented focus processes. Below is an example from Company Y (see figure 4). Fig. 4: Company Y Enterprise Process Map Company Y, although also a customer-oriented company, sends a differently focused message with its depiction of the Enterprise Process Map. Along the top of the map is the company's product tree, overarching the process areas, which when executed deliver the products themselves. This indicates one strategic objective of excellence in product quality. Additionally, the view represents a less linear value chain, with strong overlaps of the various process areas. Marketing and quality management are seen as a key support processes, as they span the process lifecycle. Often, companies may incorporate graphics, logos and symbols representing customers and suppliers, and other objects to truly send the strategic message to the business. Other times, Enterprise Process Maps may show high level of responsibility to organizational units, or the application types that support the process areas. It is possible that hundreds of formats and focuses can be applied to an Enterprise Process Map. What is of vital importance, however, is which formats and focuses are chosen to truly represent the direction of the company, and serve as a driver for focusing the business on the strategic objectives set forth in that right. Process Categorization: Customer is Core In the previous two examples, processes were grouped using differing categories and techniques. Company X showed one support and three customer process categorizations using encompassing chevron objects; Customer Y achieved a less distinct categorization using a gradual color scheme. Either way, and in general, modeling of the process areas becomes even more valuable and easily understood within the context of business categorization, be it strategic or otherwise. But how one categorizes their processes is typically more complex than simply choosing object shapes and colors. Previously, it was stated that the ideal is a prescribed top-down approach to developing processes, to make certain linkages all the way back up to corporate strategy. But what about external influences? What forces push and pull corporate strategy? Industry maturity, product lifecycle, market profitability, competition, etc. can all drive the critical success factors of a particular business segment, or the company as a whole, in addition to previous corporate strategy. This may seem to be turning into a discussion of theory, but that is far from the case. In fact, in years of recent study and evolution of the way businesses operate, cross-industry and across the globe, one invariable has surfaced with such strength to make it undeniable in the game plan of any strategy fit for survival. That constant is the customer. Many of a company's critical success factors, in any business segment, relate to the customer: customer retention, satisfaction, loyalty, etc. Businesses serve customers, and so do a business's processes, mapped or unmapped. The most effective way to categorize processes is in a manner that visualizes convergence to what is core for a company. It is the value chain, beginning with the customer in mind, and ending with the fulfillment of that customer, that becomes the core or the centerpiece of the Enterprise Process Map. (See figure 5) Fig. 5: Company Z Enterprise Process Map Company Z has what may be viewed as several different perspectives or "cuts" baked into their Enterprise Process Map. It has divided its processes into three main categories (top, middle, and bottom) of Management Processes, the Core Value Chain and Supporting Processes. The Core category begins with Corporate Marketing (which contains the activities of beginning to engage customers) and ends with Customer Service Management. Within the value chain, this company has divided into the focus areas of their two primary business lines, Foods and Beverages. Does this mean that areas, such as Strategy, Information Management or Project Management are not as important as those in the Core category? No! In some cases, though, depending on the organization's understanding of high-level BPM concepts, use of category names, such as "Core," "Management" or "Support," can be a touchy subject. What is important to understand, is that no matter the nomenclature chosen, the Core processes are those that drive directly to customer value, Support processes are those which make the Core processes possible to execute, and Management Processes are those which steer and influence the Core. Some common terms for these three basic categorizations are Core, Customer Fulfillment, Customer Relationship Management, Governing, Controlling, Enabling, Support, etc. End-to-end versus Functional Processes Every high and low level of process: function, task, activity, process/work step (whatever an organization calls it), should add value to the flow of business in an organization. Suppose that within the process "Deliver package," there is a documented task titled "Stop for ice cream." It doesn't take a process expert to deduce the room for improvement. Though stopping for ice cream may create gain for the one person performing it, it likely benefits neither the organization nor, more importantly, the customer. In most cases, "Stop for ice cream" wouldn't make it past the first pass of To-Be process development. What would make the cut, however, would be a flow of tasks that, each having their own value add, build up to greater and greater levels of process objective. In this case, those tasks would combine to achieve a status of "package delivered." Figure 3 shows a simple example: Just as the package can only be delivered (outcome of the process) without first being retrieved, loaded, and the travel destination reached (outcomes of the process steps), some higher level of process "Play Practical Joke" (e.g., main process or process area) cannot be completed until a package is delivered. It seems that isolated or functionally separated processes, such as "Deliver Package" (shown in Figure 6), are necessary, but are always part of a bigger value chain. Each of these individual processes must be analyzed within the context of that value chain in order to ensure successful end-to-end process performance. For example, this company's "Create Joke Package" process could be operating flawlessly and efficiently, but if a joke is never developed, it cannot be created, so the end-to-end process breaks. Fig. 6: End to End Process Construction That being recognized, it is clear that processes must be viewed as end-to-end, customer-to-customer, and in the context of company strategy. But as can also be seen from the previous example, these vital end-to-end processes cannot be built without the functionally oriented building blocks. Without one, the other cannot be had, or at least not in a complete and organized fashion. As it turns out, but not discussed in depth here, the process modeling effort, BPM organizational development, and comprehensive coverage cannot be fully realized without a semi-functional, process-oriented approach. Then, an Enterprise Process Map should be concerned with both views, the building blocks, and access points to the business-critical end-to-end processes, which they construct. Without the functional building blocks, all streams of work needed for any business transformation would be lost mess of process disorganization. End-to-end views are essential for utilization in optimization in context, understanding customer impacts, base-lining all project phases and aligning objectives. Including both views on an Enterprise Process Map allows management to understand the functional orientation of the company's processes, while still providing access to end-to-end processes, which are most valuable to them. (See figures 7 and 8). Fig. 7: Simplified Enterprise Process Map with end-to-end Access Point The above examples show two unique ways to achieve a successful Enterprise Process Map. The first example is a simple map that shows a high level set of process areas and a separate section with the end-to-end processes of concern for the organization. This particular map is filtered to show just one vital end-to-end process for a project-specific focus. Fig. 8: Detailed Enterprise Process Map showing connected Functional Processes The second example shows a more complex arrangement and categorization of functional processes (the names of each process area has been removed). The end-to-end perspective is achieved at this level through the connections (interfaces at lower levels) between these functional process areas. An important point to note is that the organization of these two views of the Enterprise Process Map is dependent, in large part, on the orientation of its audience, and the complexity of the landscape at the highest level. If both are not apparent, the Enterprise Process Map is missing an opportunity to serve as a holistic, high-level view. Conclusion In the world of BPM, and specifically regarding Enterprise Process Maps, a picture can be worth as many words as the thought and effort that is put into it. Enterprise Process Maps alone cannot change an organization, but they serve more purposes than initially meet the eye, and therefore must be designed in a way that enables a BPM mindset, business process understanding and business transformation efforts. Every Enterprise Process Map will and should be different when looking across organizations. Its design will be driven by company strategy, a level of customer focus, and functional versus end-to-end orientations. This high-level description of the considerations of the Enterprise Process Maps is not a prescriptive "how to" guide. However, a company attempting to create one may not have the practical BPM experience to truly explore its options or impacts to the coming work of business process transformation. The biggest takeaway is that process modeling, at all levels, is a science and an art, and art is open to interpretation. It is critical that the modeler of the highest level of process mapping be a cognoscente of the message he is delivering and the factors at hand. Without sufficient focus on the design of the Enterprise Process Map, an entire BPM effort may suffer. For additional information please check: Oracle Business Process Management.

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