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• Impressions from VMworld - Clearing up Misconceptions

  - by Monica Kumar

  Gorgeous sunny weather…none of the usual summer fog…the Oracle Virtualization team has been busy at VMworld in San Francisco this week. From the time exhibits opened on Sunday, our booth staff was fully engaged with visitors. It was great to meet with customers and prospects, and there were many…most with promises to meet again in October at Oracle OpenWorld 2012. Interests and questions ran the gamut - from implementation details to consolidating applications to how does Oracle VM enable rapid application deployment to Oracle support and licensing. All good stuff! Some inquiries are poignant and really help us get at the customer pain points. Some are just based on misconceptions. We’d like to address a couple of common misconceptions that we heard: 1) Rapid deployment of enterprise applications is great but I don’t do this all the time. So why bother? While production applications don’t get updated or upgraded as often, development and QA staging environments are much more dynamic. Also, in today’s Cloud based computing environments, end users expect an entire solution, along with the virtual machine, to be provisioned instantly, on-demand, as and when they need to scale. Whether it’s adding a new feature to meet customer demands or updating applications to meet business/service compliance, these environments undergo change frequently. The ability to rapidly stand up an entire application stack with all the components such as database tier, mid-tier, OS, and applications tightly integrated, can offer significant value. Hand patching, installation of the OS, application and configurations to ensure the entire stack works well together can take days and weeks. Oracle VM Templates provide a much faster path to standing up a development, QA or production stack in a matter of hours or minutes. I see lots of eyes light up as we get to this point of the conversation. 2) Oracle Software licensing on VMware vSphere In the world of multi-vendor IT stacks, understanding license boundaries and terms and conditions for each product in the stack can be challenging.  Oracle’s licensing, though, is straightforward.  Oracle software is licensed per physical processor in the server or cluster where the Oracle software is installed and/or running.  The use of third party virtualization technologies such as VMware is not allowed as a means to change the way Oracle software is licensed.  Exceptions are spelled out in the licensing document labeled “Hard Partitioning". Here are some fun pictures! Visitors to our booth told us they loved the Oracle SUV courtesy shuttles that are helping attendees get to/from hotels. Also spotted were several taxicabs sporting an Oracle banner! Stay tuned for more highlights across desktop and server virtualization as we wrap up our participation at VMworld.

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• Visual Studio 2010 Launch Events

  - by Jim Duffy

  Don’t miss out on the opportunity to learn about the new features in Visual Studio 2010. Check out the MSDN Events page and find out when the talented folks of the Developer & Evangelism group will be visiting your city to prove to you that /*Life Runs On Code*/. I’ll be attending the Raleigh event June 2, 2010 from 1:00 - 5:00 PM. North Carolina State University, Jane S. McKimmon Conference Center 1101 Gorman St Raleigh North Carolina 27606 United States From the Raleigh Event page: Event Overview Learn about the rich application platforms that Microsoft® Visual Studio® 2010 supports, including Windows® 7, the Web, SharePoint®, Windows Azure™, SQL®, and Windows® Phone 7 Series. From tighter tester and dev collaboration to new ALM tools, there’s a lot that’s new. Here’s what you can expect: Windows Development with Visual Studio 2010 Visual Studio has always been the best way to build compelling visual solutions for Windows. Visual Studio 2010 continues this trend with great new tooling support for Silverlight 4, WPF, and native development. In this demo heavy session, you’ll see how you can build rich Windows applications with Silverlight 4 using new trusted application features including out-of-browser execution, saving to the file system, and even COM Automation. You’ll also see how you can use the new Task Parallel Library from within a WPF application to take advantage of all those cores in today’s modern computers. Web and Cloud Development with Visual Studio 2010 If you build solutions for the web, then this session is for you. Come see how your existing skills move forward with Visual Studio 2010 both for in-house ASP.NET development and the new frontier of the Cloud. In this session, you’ll see improved designers, new HTML and JavaScript snippets, Web Forms enhancements, and how you can quickly build great web sites using Dynamic Data. You’ll see the changes made to testable web sites with MVC 2.0 and how we’ve integrated JQuery support into the platform. You’ll then see how easy it is to leverage your existing code and move to the cloud with Windows Azure. Windows Phone 7 Developer Tools and Platform Overview This session provides an overview of Visual Studio® 2010 for Windows Phone. Learn about the powerful capabilities of this new application platform and the developer tools experience including basic IDE usage, debugging, packaging, and deployment. This session also shows how you can use Microsoft Expression® Blend™ for Windows Phone to build great Silverlight applications. Have a day. :-|

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• Base Pages and Interfaces for ASP.NET Pages

  - by geekrutherford

  For quite a while I have been using the concept of base pages when developing pages in ASP.NET applications. It is a wonderful method for exposing common functions to all of your applications pages and also overriding certain events for various purposes (i.e. dynamic themes).  Recently I found out a new developer will be joining my team. This prompted me to review the applications code for readability and ease of maintenance. I began adding comments through out the code behind for all pages within the application. While doing so I noted that I had used common method names for such things as loading data, configuring controls, applying filters, etc.   Bringing a new developer on board, I wanted to make the transition as seamless as possible while also ensuring they follow existing coding practices we already have in place. While I could have created virtual methods for the common page methods allowing them to overridden, what I really needed was a way to ensure the new developer implemented the same methods for each and every page. Thus I created an interface to force the issue.   Now, every page not only inherits the base page class but also implements an interface. This provides every page not only common functions and overridden page events but also imposes rules for implementing certain common methods :-)   Interface   public interface BasePageInterface { /// Configures page based on users security permissions. void CheckPermissions(); /// Configures Filter Form control for current page.  /// Ensure you have set the FilteredGrid and PageAjaxManager properties of the FilterForm control in PageLoad!!!  void ConfigureFilters(); /// Sets event handlers and default settings for controls on the current page. void ConfigureControls(); /// Exports data bound to grid in selected format. void ExportGridData(ExportFormat fmt); /// Loads data and binds to grid. /// Columns are turned on/off in grid depending on tab selected and users permissions.  void LoadData(); }   Page code-behind class definition:   public partial class MyPage : BasePage, BasePageInterface Note, you could not use an abstract class to accomplish this considering C# does not allow for multiple inheritance.  Nor could the base page class be abstract since it needs to inherit from the System.Web.UI.Page class in order to override page events.

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• What causes Box2D revolute joints to separate?

  - by nbolton

  I have created a rag doll using dynamic bodies (rectangles) and simple revolute joints (with lower and upper angles). When my rag doll hits the ground (which is a static body) the bodies seem to fidget and the joints separate. It looks like the bodies are sticking to the ground, and the momentum of the rag doll pulls the joint apart (see screenshot below). I'm not sure if it's related, but I'm using the Badlogic GDX Java wrapper for Box2D. Here's some snippets of what I think is the most relevant code: private RevoluteJoint joinBodyParts( Body a, Body b, Vector2 anchor, float lowerAngle, float upperAngle) { RevoluteJointDef jointDef = new RevoluteJointDef(); jointDef.initialize(a, b, a.getWorldPoint(anchor)); jointDef.enableLimit = true; jointDef.lowerAngle = lowerAngle; jointDef.upperAngle = upperAngle; return (RevoluteJoint)world.createJoint(jointDef); } private Body createRectangleBodyPart( float x, float y, float width, float height) { PolygonShape shape = new PolygonShape(); shape.setAsBox(width, height); BodyDef bodyDef = new BodyDef(); bodyDef.type = BodyType.DynamicBody; bodyDef.position.y = y; bodyDef.position.x = x; Body body = world.createBody(bodyDef); FixtureDef fixtureDef = new FixtureDef(); fixtureDef.shape = shape; fixtureDef.density = 10; fixtureDef.filter.groupIndex = -1; fixtureDef.filter.categoryBits = FILTER_BOY; fixtureDef.filter.maskBits = FILTER_STUFF | FILTER_WALL; body.createFixture(fixtureDef); shape.dispose(); return body; } I've skipped the method for creating the head, as it's pretty much the same as the rectangle method (just using a cricle shape). Those methods are used like so: torso = createRectangleBodyPart(x, y + 5, 0.25f, 1.5f); Body head = createRoundBodyPart(x, y + 7.4f, 1); Body leftLegTop = createRectangleBodyPart(x, y + 2.7f, 0.25f, 1); Body rightLegTop = createRectangleBodyPart(x, y + 2.7f, 0.25f, 1); Body leftLegBottom = createRectangleBodyPart(x, y + 1, 0.25f, 1); Body rightLegBottom = createRectangleBodyPart(x, y + 1, 0.25f, 1); Body leftArm = createRectangleBodyPart(x, y + 5, 0.25f, 1.2f); Body rightArm = createRectangleBodyPart(x, y + 5, 0.25f, 1.2f); joinBodyParts(torso, head, new Vector2(0, 1.6f), headAngle); leftLegTopJoint = joinBodyParts(torso, leftLegTop, new Vector2(0, -1.2f), 0.1f, legAngle); rightLegTopJoint = joinBodyParts(torso, rightLegTop, new Vector2(0, -1.2f), 0.1f, legAngle); leftLegBottomJoint = joinBodyParts(leftLegTop, leftLegBottom, new Vector2(0, -1), -legAngle * 1.5f, 0); rightLegBottomJoint = joinBodyParts(rightLegTop, rightLegBottom, new Vector2(0, -1), -legAngle * 1.5f, 0); leftArmJoint = joinBodyParts(torso, leftArm, new Vector2(0, 1), -armAngle * 0.7f, armAngle); rightArmJoint = joinBodyParts(torso, rightArm, new Vector2(0, 1), -armAngle * 0.7f, armAngle);

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• What are the drawbacks of sending XML to browsers and let them apply XSLT?

  - by MainMa

  Context Working as a freelance developer, I often made websites completely based on XSLT. In other words, on every request, an XML file is generated, containing everything we need to know about the page content: the name of the user currently logged in, the top menu entries, if this menu is dynamic/configurable, the text to display in a specific area of the page, etc. Then XSL process (caches, etc.) it to HTML/XHTML page to send to the browser. It has a good point to make it easier to create small-scale websites, especially with PHP. It is a sort of template engine, but which I prefer to other template engines because it's much more powerful than most of template engines, and because I know it better and like it. It is also possible, when need, to give an access to raw XML data on demand for an automated access, without the need to create separate APIs. Of course, it will fail completely on any medium-scale or large-scale website, since, even with good caching techniques, XSL still degrades overall website performance and requires more CPU serverside. Question Modern browsers have the ability to take an XML file and to transform it with an associated XSL file declared in XML like <?xml-stylesheet href="demo.xslt" type="text/xsl"?>. Firefox 3 can do it. Internet Explorer 8 can do it too. It means that it is possible to migrate XSL processing from the server to the client side for 50% of users (according on browser statistics on several websites where I may want to implement this). It means that those 50% of users will receive only the XML file at each request, thus reducing their and server's bandwidth (XML file being much shorter than its processed HTML analog), and reducing server's CPU usage. What are the drawbacks of this technique? I thought about several ones, but it doesn't apply in this situation: Difficult implementation and the need to choose, based on the browser request, when to send raw XML and when to transform it to HTML instead. Obviously, the system will not be much more difficult then the actual one. The only change to make is to add XSL file link to every XML, and to add a browser check. More IO and bandwidth usage, since the XSLT file will be downloaded by the browsers, instead of being cached by the server. I don't think it will be a problem, since XSLT file will be cached by the browsers (like images, or CSS, or JavaScript files are cached actually). Possibly some problems on client side, like maybe problems when saving a page in some browsers. Difficulty to debug code: it is impossible to obtain an HTML source the browser is actually using, since the only displayed source is the downloaded XML. On the other hand, I rarely go look at HTML code on client side, and in most cases, it is unusable directly (whitespace being removed).

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• Sharing on Github

  - by Alan

  Over the past couple weeks I have gotten a lot of help from StackOverflow users on a project, and rather than keep the finished product to myself I wanted to share it unencumbered by licenses, but don't want there to be so much legwork during installation that users shy away from trying it. I am about to post it to Github and choosing public domain licensing. I would like to to be super simple for users to make use of and just FTP it up and go. That being said, do I need to make sure I remove things like the JQuery file, and other GPL / MIT licensed dependencies that I didn't write but that my code depends on? I haven't removed any copyright notices from the other code and all of it open source, it would just be nice if users could download everything at once while of course not trying to represent that I am the license holder of the dependencies. Inside my files are also some snippets, do those have to be externalized with installation instructions or can it be posted as is? Here is an example, my nav.php file is 115 lines long and I have these at the top: <script type="text/javascript" src="./js/ddaccordion.js"> /*********************************************** * Accordion Content script- (c) Dynamic Drive DHTML code library (www.dynamicdrive.com) * Visit http://www.dynamicDrive.com for hundreds of DHTML scripts * This notice must stay intact for legal use ***********************************************/ </script> <link href="css/admin.css" rel="stylesheet"> <script type="text/javascript"> ddaccordion.init({ headerclass: "submenuheader", //Shared CSS class name of headers group contentclass: "submenu", //Shared CSS class name of contents group revealtype: "click", //Reveal content when user clicks or onmouseover the header? Valid value: "click", "clickgo", or "mouseover" mouseoverdelay: 200, //if revealtype="mouseover", set delay in milliseconds before header expands onMouseover collapseprev: false, //Collapse previous content (so only one open at any time)? true/false defaultexpanded: [], //index of content(s) open by default [index1, index2, etc] [] denotes no content onemustopen: false, //Specify whether at least one header should be open always (so never all headers closed) animatedefault: false, //Should contents open by default be animated into view? persiststate: true, //persist state of opened contents within browser session? toggleclass: ["", ""], //Two CSS classes to be applied to the header when it's collapsed and expanded, respectively ["class1", "class2"] togglehtml: ["suffix", "<img src='./images/plus.gif' class='statusicon' />", "<img src='./images/minus.gif' class='statusicon' />"], //Additional HTML added to the header when it's collapsed and expanded, respectively ["position", "html1", "html2"] (see docs) animatespeed: "fast", //speed of animation: integer in milliseconds (ie: 200), or keywords "fast", "normal", or "slow" oninit:function(headers, expandedindices){ //custom code to run when headers have initalized //do nothing }, onopenclose:function(header, index, state, isuseractivated){ //custom code to run whenever a header is opened or closed //do nothing } }) </script>

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• Creating smooth lighting transitions using tiles in HTML5/JavaScript game

  - by user12098

  I am trying to implement a lighting effect in an HTML5/JavaScript game using tile replacement. What I have now is kind of working, but the transitions do not look smooth/natural enough as the light source moves around. Here's where I am now: Right now I have a background map that has a light/shadow spectrum PNG tilesheet applied to it - going from darkest tile to completely transparent. By default the darkest tile is drawn across the entire level on launch, covering all other layers etc. I am using my predetermined tile sizes (40 x 40px) to calculate the position of each tile and store its x and y coordinates in an array. I am then spawning a transparent 40 x 40px "grid block" entity at each position in the array The engine I'm using (ImpactJS) then allows me to calculate the distance from my light source entity to every instance of this grid block entity. I can then replace the tile underneath each of those grid block tiles with a tile of the appropriate transparency. Currently I'm doing the calculation like this in each instance of the grid block entity that is spawned on the map: var dist = this.distanceTo( ig.game.player ); var percentage = 100 * dist / 960; if (percentage < 2) { // Spawns tile 64 of the shadow spectrum tilesheet at the specified position ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 64 ); } else if (percentage < 4) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 63 ); } else if (percentage < 6) { ig.game.backgroundMaps[2].setTile( this.pos.x, this.pos.y, 62 ); } // etc... (sorry about the weird spacing, I still haven't gotten the hang of pasting code in here properly) The problem is that like I said, this type of calculation does not make the light source look very natural. Tile switching looks too sharp whereas ideally they would fade in and out smoothly using the spectrum tilesheet (I copied the tilesheet from another game that manages to do this, so I know it's not a problem with the tile shades. I'm just not sure how the other game is doing it). I'm thinking that perhaps my method of using percentages to switch out tiles could be replaced with a better/more dynamic proximity forumla of some sort that would allow for smoother transitions? Might anyone have any ideas for what I can do to improve the visuals here, or a better way of calculating proximity with the information I'm collecting about each tile? (PS: I'm reposting this from Stack Overflow at someone's suggestion, sorry about the duplicate!)

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• Are there any concerns with using a static read-only unit of work so that it behaves like a cache?

  - by Rowan Freeman

  Related question: How do I cache data that rarely changes? I'm making an ASP.NET MVC4 application. On every request the security details about the user will need to be checked with the area/controller/action that they are accessing to see if they are allowed to view it. The security information is stored in the database. For example: User Permission UserPermission Action ActionPermission A "Permission" is a token that is applied to an MVC action to indicate that the token is required in order to access the action. Once a user is given the permission (via the UserPermission table) then they have the token and can therefore access the action. I've been looking in to how to cache this data (since it rarely changes) so that I'm only querying in-memory data and not hitting a database (which is a considerable performance hit at the moment). I've tried storing things in lists, using a caching provider but I either run in to problems or performance doesn't improve. One problem that I constantly run in to is that I'm using lazy loading and dynamic proxies with EntityFramework. This means that even if I ToList() everything and store them somewhere static, the relationships are never populated. For example, User.Permissions is an ICollection but it's always null. I don't want to Include() everything because I'm trying to keep things simple and generic (and easy to modify). One thing I know is that an EntityFramework DbContext is a unit of work that acts with 1st-level caching. That is, for the duration of the unit of work, everything that is accessed is cached in memory. I want to create a read-only DbContext that will exist indefinitely and will only be used to read about permission data. Upon testing this it worked perfectly; my page load times went from 200ms+ to 20ms. I can easily force the data to refresh at certain intervals or simply leave it to refresh when the application pool is recycled. Basically it will behave like a cache. Note that the rest of the application will interact with other contexts that exist per request as normal. Is there any disadvantage to this approach? Could I be doing something different?

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• Was I wrong about JavaScript?

  - by jboyer

  Yes, I was. Recently, I’ve taken a good hard look at JavaScript. I’ve used it before but mostly in the capacity of web design. Using JQuery to make your web page do cool stuff is different than really creating a JavaScript application using all of the language constructs. What I’m finding as I use it more is that I may have been wrong about my assumptions about it. Let me explain.   I enjoyed doing cool stuff with JQuery but the limited experience with JavaScript as a language coupled with the bad things that I heard about it led me to not have any real interest in it. However, JavaScript is ubiquitous on the web and if I want to do any web development, which I do, I need to learn it. So here I am, diving deep into the language with the help of the JavaScript Fundamentals training course at Pluralsight (great training for a low price) and the JavaScript: The Good Parts book by Douglas Crockford.   Now, there are certainly parts of JavaScript that are bad. I think these are well known by any developer that uses it. The parts that I feel are especially egregious are the following: The global object null vs. undefined truthy and falsy limited (nearly nonexistent) scoping ‘==’ and ‘===’ (I just don’t get the reason for coercion)   However, what I am finding hiding under the covers of the bad things is a good language. I am finding that I am legitimately enjoying JavaScript. This I was not expecting. I’m not going to go into a huge dissertation on what I like about it, but some things include: Object literal notation dynamic typing functional style (JavaScript: The Good Parts describes it as LISP in C clothing) JSON (better than XML) There are parts of JavaScript that seem strange to OOP developers like myself. However, just because it is different or seems strange does not mean it is bad. Some differences are quite interesting and useful.   I feel that it is important for developers to challenge their assumptions and also to be able to admit when they are wrong on a topic. Many different situations can arise that lead to this, such as choosing the wrong technology for a problem’s solution, misunderstanding the requirements, etc. I decided to challenge my assumptions about JavaScript instead of moving straight into CoffeeScript or Dart. After exploring it, I find that I am beginning to enjoy it the more I use it. As long as there are those like Crockford to help guide me in the right way to code in JavaScript, I can create elegant and efficient solutions to problems and add another ‘arrow’ to the ‘quiver’, so to speak. I do still intend to learn CoffeeScript to see what the hub-bub is about, but now I no longer have to be afraid of JavaScript as a legitimate programming language.   Has something similar ever happened to you? Tell me about it in the comments below.

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• Wrapping REST based Web Service

  - by PaulPerry

  I am designing a system that will be running online under Microsoft Windows Azure. One component is a REST based web service which will really be a wrapper (using proxy pattern) which calls the REST web services of a business partner, which has to do with BLOB storage (note: we are not using azure storage). The majority of the functionality will be taking a request, calling our partner web service, receiving the request and then passing that back to the client. There are a number of reasons for doing this, but one of the big ones is that we are going to support three clients: our desktop application (win and mac), mobile apps (iOS), and a web front end. Having a single API which we then send to our partner protects us if that partner ever changes. I want our service to support both JSON and XML for the data transfer format, JSON for web and probably XML for the desktop and mobile (we already have an XML parser in those products). Our partner also supports both of these formats. I was planning on using ASP.NET MVC 4 with the Web API. As I design this, the thing that concerns me is the static type checking of C#. What if the partner adds or removes elements from the data? We can probably defensively code for that, but I still feel some concern. Also, we have to do a fair amount of tedious coding, to setup our API and then to turn around and call our partner’s API. There probably is not much choice on it though. But, in the back of my mind I wonder if maybe a more dynamic language would be a better choice. I want to reach out and see if anybody has had to do this before, what technology solutions they have used to (I am not attached to this one, these days Azure can host other technologies), and if anybody who has done something like this can point out any issues that came up. Thanks! Researching the issue seems to only find solutions which focus on connecting a SOAP web service over a proxy server, and not what I am referring to here. Note: Cross posted (by suggestion) from http://stackoverflow.com/questions/11906802/wrapping-rest-based-web-service Thank you!

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• Pretty URL in ADF Faces of JDeveloper 11.1.2.2

  - by Frank Nimphius

  Many features planned for Oracle JDeveloper 12c find their way into current releases of Oracle JDeveloper 11g R1 and JDeveloper 11g R2. One example of such a feature is "pretty URL" - or "clean URL" as the Oracle JDeveloper 11g R2 (11.1.2.2) documentation puts it. "A.2.3.24 Clean URLs Historically, ADF Faces has used URL parameters to hold information, such as window IDs and state. However, URL parameters can prevent search engines from recognizing when URLs are actually the same, and therefore interfere with analytics. URL parameters can also interfere with bookmarking. By default, ADF Faces removes URL parameters using the HTML5 History Management API. If that API is unavailable, then session cookies are used.You can also manually configure how URL parameters are removed using the context parameter oracle.adf.view.rich.prettyURL.OPTIONS. Set the parameter to off so that no parameters are removed. Set the parameter to useHistoryApi to only use the HTML5 History Management API. If a browser does not support this API, then no parameters will be removed. Set the parameter to useCookies to use session cookies to remove parameters. If the browser does not support cookies, then no parameters will be removed." See: http://docs.oracle.com/cd/E26098_01/web.1112/e16181/ap_config.htm#ADFUI12856 So basically, what this part in the documentation says is: In JDeveloper 11g R2 (11.1.2.2), Oracle ADF Faces automatically removes its internally used dynamic parameters from the URL You can influence the setting with the prettyURL.OPTIONS context option, which however is not recommended you to do because the default behavior is able to detect if the browser client supports HTML 5 History management or not. In the latter case it the uses a session cookie and if this doesn't work, falls back to the "old" URL parameter adding. The information that is not so explicit and clearly mentioned in the documentation is that this is only for ADF Faces parameters (such as _afrLoop, Adf-Window-Id, etc.), but not the ADF controller token (_adf.ctrl-state)! Removing the ADF controller token is an enhancement request that will be implemented in Oracle JDeveloper 12c

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• Event Driven Behavior Tree: deterministic traversal order with parallel

  - by Heisenbug

  I've studied several articles and listen some talks about behavior trees (mostly the resources available on AIGameDev by Alex J. Champandard). I'm particularly interested on event driven behavior trees, but I have still some doubts on how to implement them correctly using a scheduler. Just a quick recap: Standard Behavior Tree Each execution tick the tree is traversed from the root in depth-first order The execution order is implicitly expressed by the tree structure. So in the case of behaviors parented to a parallel node, even if both children are executed during the same traversing, the first leaf is always evaluated first. Event Driven BT During the first traversal the nodes (tasks) are enqueued using a scheduler which is responsible for updating only running ones every update The first traversal implicitly produce a depth-first ordered queue in the scheduler Non leaf nodes stays suspended mostly of the time. When a leaf node terminate(either with success or fail status) the parent (observer) is waked up allowing the tree traversing to continue and new tasks will be enqueued in the scheduler Without parallel nodes in the tree there will be up to 1 task running in the scheduler Without parallel nodes, the tasks in the queue(excluding dynamic priority implementation) will be always ordered in a depth-first order (is this right?) Now, from what is my understanding of a possible implementation, there are 2 requirements I think must be respected(I'm not sure though): Now, some requirements I think needs to be guaranteed by a correct implementation are: The result of the traversing should be independent from which implementation strategy is used. The traversing result must be deterministic. I'm struggling trying to guarantee both in the case of parallel nodes. Here's an example: Parallel_1 -->Sequence_1 ---->leaf_A ---->leaf_B -->leaf_C Considering a FIFO policy of the scheduler, before leaf_A node terminates the tasks in the scheduler are: P1(suspended),S1(suspended),leaf_A(running),leaf_C(running) When leaf_A terminate leaf_B will be scheduled (at the end of the queue), so the queue will become: P1(suspended),S1(suspended),leaf_C(running),leaf_B(running) In this case leaf_B will be executed after leaf_C at every update, meanwhile with a non event-driven traversing from the root node, the leaf_B will always be evaluated before leaf_A. So I have a couple of question: do I have understand correctly how event driven BT work? How can I guarantee the depth first order is respected with such an implementation? is this a common issue or am I missing something?

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• Jitter during wall collisions with Bullet Physics: contact/penetration tolerance?

  - by Niriel

  I use the bullet physics engine through Panda3d. My scene is still very simple, think 'Wolfenstein3d': tile-based, walls are solid cubes. I expect walls to block the player, and I expect the player to slide along the walls in case of non-normal incidence. What I get is what I expect, with one difference: there is some jitter. If I try to force myself into the wall, then I see the frames blinking quickly between two positions. These differ by about 0.04 units of distance, which corresponds to 4 cm in my game. I noticed a 4 cm elsewhere: the bottom of my player capsule is 4 cm below ground, when at rest. Does that mean that there is somewhere in the Bullet engine a default 0.04-units-long tolerance to differentiate contact from collision? If so, what should I do ? Should I change the scale of my game so that these 0.04 units correspond to 0.4 cm, making the jitter ten times smaller? Or can I ask bullet to change its tolerance to a smaller value? Edit This is the jitter I get: 6.155 - 6.118 = 0.036 LPoint3f(0, 6.11694, 0.835) LPoint3f(0, 6.15499, 0.835) LPoint3f(0, 6.11802, 0.835) LPoint3f(0, 6.15545, 0.835) LPoint3f(0, 6.11817, 0.835) LPoint3f(0, 6.15726, 0.835) LPoint3f(0, 6.11876, 0.835) LPoint3f(0, 6.15911, 0.835) LPoint3f(0, 6.11937, 0.835) I found a setMargin method. I set it to 5 mm both on the BoxShape for the walls and on the Capsule shape for the player. It still jitters by about 35 mm as illustrated by this log (11.117 - 11.082 = 0.035): LPoint3f(0, 11.0821, 0.905) LPoint3f(0, 11.1169, 0.905) LPoint3f(0, 11.082, 0.905) LPoint3f(0, 11.117, 0.905) LPoint3f(0, 11.082, 0.905) LPoint3f(0, 11.117, 0.905) LPoint3f(0, 11.0821, 0.905) LPoint3f(0, 11.1175, 0.905) LPoint3f(0, 11.0822, 0.905) LPoint3f(0, 11.1178, 0.905) LPoint3f(0, 11.0823, 0.905) LPoint3f(0, 11.1183, 0.905) The margin on the capsule did change my penetration with the floor though, I'm a bit higher (0.905 instead of 0.835). However, it did not change anything when colliding with the walls. How can I make the collisions against the walls less jittery? Edit, the day after: After more investigation, it appears that dynamic objects behave well. My problem comes from the btKinematicCharacterController that I use for moving my character; that stuff is totally bugged, according to the whole Internet :/.

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• ArchBeat Link-o-Rama for 2012-10-12

  - by Bob Rhubart

  This is your brain on IT architecture. Oracle Technology Network Architect Day in Los Angeles, Oct 25 This is your brain on IT architecture. Stuff your cranium with architecture by attending Oracle Technology Network Architect Day in Los Angeles, October 25, 2012, at the Sofitel Los Angeles, 8555 Beverly Boulevard, Los Angeles, CA 90048. Technical sessions, panel Q&A, and peer roundtables--plus a free lunch. Register now. WebCenter Sites Gadget Development Concepts Quickstart | John Brunswick What are Gadgets? "At their most basic level they can be thought of as lightweight portlets that run largely on the client side of an architecture," says John Brunswick. "Gadgets provide a cross-platform container to run reusable UI modules that generally expose dynamic information to an end user, allowing for some level of end user customization." ORCLville: OOW 2012 - A Not So Brief Recap Oracle ACE Director Floyd Teter, an Applications & Apps Technology specialists, shares his personal, frank, and and extensive recap or Oracle OpenWorld 2012. Fusion Applications Technical Tips | Naveen Nahata "Setting memory parameters for Admin and Managed servers of various domains in Fusion Applications can be, let us say, a little daunting," says Oracle Fusion Middleware A-Team member Naveen Nahata. "While all this may look complicated and intimidating, it is actually relatively simple once you understand how it all works." Following the Thread in OSB | Antony Reynolds Antony Reynolds recently led an Oracle Service Bus POC in which his team needed to get high throughput from an OSB pipeline. "Imagine our surprise when, on stressing the system, we saw it lock up, with large numbers of blocked threads." He shares the details of the problem and the solution in this extensive technical post. ExaLogic Hackers Night - November 19th Nürnberg Germany | WebLogic Partner Community EMEA Want to get your hands on Oracle Exalogic? Make your way to Nürnberg, Germany for this Exalogic Hacker's Night on November 19, 2012. Experts will be on hand to help you test your ideas. (The blog post is in English, but the event registration page is in German.) Thought for the Day "A foolish consistency is the hobgoblin of little minds…" — Ralph Waldo Emerson (May 25, 1803 – April 27, 1882) Source: SoftwareQuotes.com

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• Unable to find good parameters for behavior of a puck in Farseer

  - by Krumelur

  EDIT: I have tried all kinds of variations now. The last one was to adjust the linear velocity in each step: newVel = oldVel * 0.9f - all of this including your proposals kind of work, however in the end if the velocity is little enough, the puck sticks to the wall and slides either vertically or horizontally. I can't get rid of this behavior. I want it to bounce, no matter how slow it is. Retitution is 1 for all objects, Friction is 0 for all. There is no gravity. What am I possibly doing wrong? In my battle to learn and understand Farseer I'm trying to setup a simple Air Hockey like table with a puck on it. The table's border body is made up from: Vertices aBorders = new Vertices( 4 ); aBorders.Add( new Vector2( -fHalfWidth, fHalfHeight ) ); aBorders.Add( new Vector2( fHalfWidth, fHalfHeight ) ); aBorders.Add( new Vector2( fHalfWidth, -fHalfHeight ) ); aBorders.Add( new Vector2( -fHalfWidth, -fHalfHeight ) ); FixtureFactory.AttachLoopShape( aBorders, this ); this.CollisionCategories = Category.All; this.CollidesWith = Category.All; this.Position = Vector2.Zero; this.Restitution = 1f; this.Friction = 0f; The puck body is defined with: FixtureFactory.AttachCircle( DIAMETER_PHYSIC_UNITS / 2f, 0.5f, this ); this.Restitution = 0.1f; this.Friction = 0.5f; this.BodyType = FarseerPhysics.Dynamics.BodyType.Dynamic; this.LinearDamping = 0.5f; this.Mass = 0.2f; I'm applying a linear force to the puck: this.oPuck.ApplyLinearImpulse( new Vector2( 1f, 1f ) ); The problem is that the puck and the walls appear to be sticky. This means that the puck's velocity drops to zero to quickly below a certain velocity. The puck gets reflected by the walls a couple of times and then just sticks to the left wall and continues sliding downwards the left wall. This looks very unrealistic. What I'm really looking for is that a puck-wall-collision does slow down the puck only a tiny little bit. After tweaking all values left and right I was wondering if I'm doing something wrong. Maybe some expert can comment on the parameters?

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• A solution for a PHP website without a framework

  - by lortabac

  One of our customers asked us to add some dynamic functionality to an existent website, made of several static HTML pages. We normally work with an MVC framework (mostly CodeIgniter), but in this case moving everything to a framework would require too much time. Since it is not a big project, not having the full functionality of a framework is not a problem. But the question is how to keep code clean. The solution I came up with is to divide code in libraries (the application's API) and models. So inside HTML there will only be API calls, and readability will not be sacrificed. I implemented this with a sort of static Registry (sorry if I'm wrong, I am not a design pattern expert): <?php class Custom_framework { //Global database instance private static $db; //Registered models private static $models = array(); //Registered libraries private static $libraries = array(); //Returns a database class instance static public function get_db(){ if(isset(self::$db)){ //If instance exists, returns it return self::$db; } else { //If instance doesn't exists, creates it self::$db = new DB; return self::$db; } } //Returns a model instance static public function get_model($model_name){ if(isset(self::$models[$model_name])){ //If instance exists, returns it return self::$models[$model_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/models/' . $model_name . '.php')){ include_once ROOT_DIR . 'application/models/' . $model_name . '.php'; self::$models[$model_name] = new $model_name; return self::$models[$model_name]; } else { return FALSE; } } } //Returns a library instance static public function get_library($library_name){ if(isset(self::$libraries[$library_name])){ //If instance exists, returns it return self::$libraries[$library_name]; } else { //If instance doesn't exists, creates it if(is_file(ROOT_DIR . 'application/libraries/' . $library_name . '.php')){ include_once ROOT_DIR . 'application/libraries/' . $library_name . '.php'; self::$libraries[$library_name] = new $library_name; return self::$libraries[$library_name]; } else { return FALSE; } } } } Inside HTML, API methods are accessed like this: <?php echo Custom_framework::get_library('My_library')->my_method(); ?> It looks to me as a practical solution. But I wonder what its drawbacks are, and what the possible alternatives.

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• Ubuntu 13.XX unable to mount USB HDD. Tried everything. I/O error boot sector/file system

  - by XaviGG

  I know that there are many posts related but none of them helped me. I will jump to the last test because it is the one that should work, but it does not. An external HDD with single partition slow NTFS formatted in Windows, empty and clean. Checked for errors, it tells that not errors where found. Moving to Ubutnu 13.04... Gparted throws the first error when trying to read the disk: Input/output error It appears as unknown the content of the disk. Unable to create partition table or format it, getting the same error when trying. If I try to mount it in the terminal it tells me the same, specifying that also there is an I/O error reading the boot sector. I have this problem since I upgraded (always with fresh install) to 13.04. I thought it will be solved by the 13.10 but it has the same behavior. I tried with two different HDD (HD and SSHD) that work perfectly in Windows 7. In 13.04 at least I got a trying of mounting where the icon of the drive started showing and disappearing until finally it disappeared. But now it doesn't even try. Possible causes: -The HDD was my old main HDD, so it had WIN,RECOVERY,SYSTEM,UBU,SWAP partitions. Maybe the way or place where the partition table is defined is not the best for an external HDD but I don't know a lot in that topic. I would appreciate a lot if someone can give me a guideline to convert one of these HDD in a working external HDD. No files to recover, nothing to care about. Just format completely the disk and be able to use it for storing backups without having to move the files first to the windows partition, load windows and then copy them to the external HDD. Because I want to use a file comparator for the backups. Thanks a lot Edit 1: I found an option in Windows to convert it to a dynamic HDD that warns me that I wont be able to run O.S. after changing. I suppose that is what I need because in the current mode I cannot safely extract it. But it tells me an error that it couldn't change the mode.

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• WHERE x = @x OR @x IS NULL

  - by steveh99999

  Every SQL DBA and developer should read the blog of MVP Erland Sommarskog – but particularly  his article on dynamic search conditions in T-SQL. I’ve linked above to his SQL 2005 article but his 2008 version is also a must-read. I seem to regularly come across uses of the SQL in the title above… Erland’s article explains in detail why this is inefficient, but I came across a nice example recently… A stored procedure contained the following code :- WHERE @Name is null or [Name] like @Name as a nonclustered index exists on the Name column, you might assume this would be handled efficiently by SQL Server. However, I got the following output from SET STATISTICS IO Table 'xxxxx'. Scan count 15, logical reads 47760, physical reads 9, read-ahead reads 13872, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. Note the high number of logical reads… After a bit of investigation, we found that @Name could never actually be set to NULL in this particular example. ie the @x IS NULL was spurious… So, we changed the call to WHERE  [Name] like @Name Now, how much more efficient is this code ? Table 'xxxxx'. Scan count 3, logical reads 24, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0 A nice easy win in this case…… a full index scan has been replaced by a significantly more efficient index seek. I managed to recreate the same behaviour on Adventureworks – here’s a quick query to demonstrate :- USE adventureworks SET STATISTICS IO ON DECLARE @id INT = 51721 SELECT * FROM Sales.SalesOrderDetail WHERE @id IS NULL OR salesorderid = @id SELECT * FROM Sales.SalesOrderDetail WHERE salesorderid = @id Take a look at the STATISTICS IO output and compare the actual query plans used to prove the impact of  WHERE @id IS NULL. And just to follow some of Erland’s advice – here’s how you could get similar performance if it was possible that @id could actually sometimes contain NULL. DECLARE @sql NVARCHAR(4000), @parameterlist NVARCHAR(4000) DECLARE @id INT = 51721 – or change to NULL to prove query is functionally correct SET @sql = 'SELECT * FROM Sales.SalesOrderDetail WHERE 1 = 1' IF @id IS NOT NULL SET @sql = @sql + ' AND salesorderid = @id' IF @id IS NULL SET @sql = @sql + ' AND salesorderid IS NULL' SET @parameterlist = '@id INT' EXEC sp_executesql @sql, @parameterlist,@id Sometimes I think we focus too much on hardware and SQL Server configuration – when really the answer is focus on writing efficient SQL.

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• Is there a factory pattern to prevent multiple instances for same object (instance that is Equal) good design?

  - by dsollen

  I have a number of objects storing state. There are essentially two types of fields. The ones that uniquely define what the object is (what node, what edge etc), and the others that store state describing how these things are connected (this node is connected to these edges, this edge is part of these paths) etc. My model is updating the state variables using package methods, so all these objects act as immutable to anyone not in Model scope. All Objects extend one base type. I've toyed with the idea of a Factory approach which accepts a Builder object and constructs the applicable object. However, if an instance of the object already exists (ie would return true if I created the object defined by the builder and passed it to the equal method for the existing instance) the factory returns the current object instead of creating a new instance. Because the Equal method would only compare what uniquely defines the type of object (this is node A to node B) but won't check the dynamic state stuff (node A is currently connected to nodes C and E) this would be a way of ensuring anyone that wants my Node A automatically knows its state connections. More importantly it would prevent aliasing nightmares of someone trying to pass an instance of node A with different state then the node A in my model has. I've never heard of this pattern before, and it's a bit odd. I would have to do some overriding of serialization methods to make it work (ensure that when I read in a serilized object I add it to my facotry list of known instances, and/or return an existing factory in its place), as well as using a weakHashMap as if it was a weakHashSet to know whether an instance exists without worrying about a quasi-memory leak occuring. I don't know if this is too confusing or prone to its own obscure bugs. One thing I know is that plugins interface with lowest level hardware. The plugins have to be able to return state that is different than my memory; to tell my memory when its own state is inconsistent. I believe this is possible despite their fetching objects that exist in my memory; we allow building of objects without checking their consistency with the model until the addToModel is called anyways; and the existing plugins design was written before all this extra state existed and worked fine without ever being aware of it. Should I just be using some other design to avoid this crazyness? (I have another question to that affect that I'm posting).

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• Practices for domain models in Javascript (with frameworks)

  - by AndyBursh

  This is a question I've to-and-fro'd with for a while, and searched for and found nothing on: what're the accepted practices surrounding duplicating domain models in Javascript for a web application, when using a framework like Backbone or Knockout? Given a web application of a non-trivial size with a set of domain models on the server side, should we duplicate these models in the web application (see the example at the bottom)? Or should we use the dynamic nature to load these models from the server? To my mind, the arguments for duplicating the models are in easing validation of fields, ensuring that fields that expected to be present are in fact present etc. My approach is to treat the client-side code like an almost separate application, doing trivial things itself and only relying on the server for data and complex operations (which require data the client-side doesn't have). I think treating the client-side code like this is akin to separation between entities from an ORM and the models used with the view in the UI layer: they may have the same fields and relate to the same domain concept, but they're distinct things. On the other hand, it seems to me that duplicating these models on the server side is a clear violation of DRY and likely to lead to differing results on the client- and server-side (where one piece gets updated but the other doesn't). To avoid this violation of DRY we can simply use Javascripts dynamism to get the field names and data from the server as and when they're neeed. So: are there any accepted guidelines around when (and when not) to repeat yourself in these situations? Or this a purely subjective thing, based on the project and developer(s)? Example Server-side model class M { int A DateTime B int C int D = (A*C) double SomeComplexCalculation = ServiceLayer.Call(); } Client-side model function M(){ this.A = ko.observable(); this.B = ko.observable(); this.C = ko.observable(); this.D = function() { return A() * C(); } this.SomeComplexCalculation = ko.observalbe(); return this; }l M.GetComplexValue = function(){ this.SomeComplexCalculation(Ajax.CallBackToServer()); }; I realise this question is quite similar to this one, but I think this is more about almost wholly untying the web application from the server, where that question is about doing this only in the case of complex calculation.

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• is a factory pattern to prevent multuple instances for same object (instance that is Equal) good design?

  - by dsollen

  I have a number of objects storing state. There are essentially two types of fields. The ones that uniquly define what the object is (what node, what edge etc), and the oens that store state describing how these things are connected (this node is connected to these edges, this edge is part of these paths) etc. My model is updating the state variables using package methdos, so these objects all act as immutable to anyone not in Model scope. All Objects extend one base type. I've toyed with the idea of a Factory approch which accepts a Builder object and construct the applicable object. However, if an instance of the object already exists (ie would return true if I created the object defined by the builder and passed it to the equal method for the existing instance) the factory returns the current object instead of creating a new instance. Because the Equal method would only compare what uniquly defines the type of object (this is node A nto node B) but won't check the dynamic state stuff (node A is currently connected to nodes C and E) this would be a way of ensuring anyone that wants my Node A automatically knows it's state connections. More importantly it would prevent aliasing nightmares of someone trying to pass an instance of node A with different state then the node A in my model has. I've never heard of this pattern before, and it's a bit odd. I would have to do some overiding of serlization methods to make it work (ensure when I read in a serilized object I add it to my facotry list of known instances, and/or return an existing factory in it's place), as well as using a weakHashMap as if it was a weakHashSet to know rather an instance exists without worrying about a quasi-memory leak occuring. I don't know if this is too confusing or prone to it's own obscure bugs. One thing I know is that plugins interface with lowest level hardware. The plugins have to be able to return state taht is different then my memory; to tell my memory when it's own state is inconsistent. I believe this is possible despit their fetching objects that exist in my memory; we allow building of objects without checking their consistency with the model until the addToModel is called anyways; and the existing plugins design was written before all this extra state existed and worked fine without ever being aware of it. Should I just be using some other design to avoid this crazyness? (I have another question to that affect I'm posting).

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• Developing web sites that imitate desktop apps. How to fight that paradigm? [closed]

  - by user1598390

  Supposse there's a company where web sites/apps are designed to resemble desktop apps. They struggle to add: Splash screens Drop-down menus Tab-pages Pages that don't grow downward with content, context is inside scrollable area so page is of a fixed size, as if resembling the one-screen limitation of desktop apps. Modal windows, pop-ups, etc. Tree views Absolutely no access to content unless you login-first, even with non-sensitive content. After splash screen desapears, you are presented with a login screen. No links - just simulated buttons. Fixed page-size. Cannot open a linked in other tab Print button that prints directly ( not showing printable page so the user can't print via the browser's print command ) Progress bars for loading content even when the browser indicates it with its own animation Fonts and color amulate a desktop app made with Visual Basic, PowerBuilder etc. Every app seems almost as if were made in Visual Basic. They reject this elements: Breadcrumbs Good old underlined links Generated/dynamic navigation, usage-based suggestions Ability to open links in multiple tabs Pagination Printable pages Ability to produce a URL you can save or share that links to an item, like when you send someone the link to an especific StackExchange question. The only URL is the main one. Back button To achieve this, tons of javascript code is needed. Lots and lots of Javascript and Ajax code for things not related with the business but with the necessity to hide/show that button, refresh this listbox, grey-out that label, etc. The coplexity generated by forcing one paradigm into another means most lines of code are dedicated to maintain the illusion of a desktop app. What is the best way to change this mindset, and make them embrace the web, and start producing modern, web apps instead of desktop imitations ? EDIT: These sites are intranet sites. Users hate these apps. They constantly whine about them, but they have to use them to do their daily work. These sites are in-house solutions, the end-users have no choice but to use them. They are a "captive audience". Also, substitution will not happen because of high costs. But at least if that mindset is changed, new developments would be more web-like.

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• Get Proactive With AutoVue Support!

  - by GrahamOracle

  v\:* {behavior:url(#default#VML);} o\:* {behavior:url(#default#VML);} w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);} I’m pleased to announce the AutoVue “Get Proactive” page within the My Oracle Support portal. This new dynamic document links to valuable resources for AutoVue users, administrators, and integrators – Not only to remain up-to-date on Support and technical topics, but also to enhance your knowledge in planning for upgrade and maintenance activities for your AutoVue products. To access the AutoVue Get Proactive page, log into the MOS portal, search for note number 432.1 in the search field at the top-right, and once in the document select “Agile and AutoVue” from the dropdown (as shown in the following screenshot): The Get Proactive page is a working document, and we plan to include new resources as they become available. Therefore make sure to bookmark the document, and if you have any suggestions please post them using the ‘Add Comment’ feature within the document, or through the AutoVue Community. Normal 0 false false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}

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• How to set up an rsync backup to Ubuntu securely?

  - by ws_e_c421

  I have been following various other tutorials and blog posts on setting up a Ubuntu machine as a backup "server" (I'll call it a server, but it's just running Ubuntu desktop) that I push new files to with rsync. Right now, I am able to connect to the server from my laptop using rsync and ssh with an RSA key that I created and no password prompt when my laptop is connected to my home router that the server is also connected to. I would like to be able to send files from my laptop when I am away from home. Some of the tutorials I have looked at had some brief suggestions about security, but they didn't focus on them. What do I need to do to let my laptop with send files to the server without making it too easy for someone else to hack into the server? Here is what I have done so far: Ran ssh-keygen and ssh-copy-id to create a key pair for my laptop and server. Created a script on the server to write its public ip address to a file, encrypt the file, and upload to an ftp server I have access to (I know I could sign up for a free dynamic DNS account for this part, but since I have the ftp account and don't really need to make the ip publicly accessible I thought this might be better). Here are the things I have seen suggested: Port forwarding: I know I need to assign the server a fixed ip address on the router and then tell the router to forward a port or ports to it. Should I just use port 22 or choose a random port and use that? Turn on the firewall (ufw). Will this do anything, or will my router already block everything except the port I want? Run fail2ban. Are all of those things worth doing? Should I do anything else? Could I set up the server to allow connections with the RSA key only (and not with a password), or will fail2ban provide enough protection against malicious connection attempts? Is it possible to limit the kinds of connections the server allows (e.g. only ssh)? I hope this isn't too many questions. I am pretty new to Ubuntu (but use the shell and bash scripts on OSX). I don't need to have the absolute most secure set up. I'd like something that is reasonably secure without being so complicated that it could easily break in a way that would be hard for me to fix.

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• Development Approach: User Interface In or Domain Model Out?

  - by Berin Loritsch

  While I've never delivered anything using Smalltalk, my brief time playing with it has definitely left its mark. The only way to describe the experience is MVC the way it was meant to be. Essentially, all the heavy lifting for your application is done in the business objects (or domain model if you are so inclined). The standard controls are bound to the business objects in some way. For example, a text box is mapped to an object's field (the field itself is an object so it's easy to do). A button would mapped to a method. This is all done with a very simple and natural API. We don't have to think about binding objects, etc. It just works. Yet, in many newer languages and APIs you are forced to think from the outside in. First with C++ and MFC, and now with C# and WPF, Microsoft has gotten it's developer world hooked on GUI builders where you build your application by implementing event handlers. Java Swing development isn't so different, only you are writing the code to instantiate the controls on the form yourself. For some projects, there may never even be a domain model--just event handlers. I've been in and around this model for most of my carreer. Each way forces you to think differently. With the Smalltalk approach, your domain is smart while your GUI is dumb. With the default VisualStudio approach, your GUI is smart while your domain model (if it exists) is rather anemic. Many developers that I work with see value in the Smalltalk approach, and try to shoehorn that approach into the VisualStudio environment. WPF has some dynamic binding features that makes it possible; but there are limitations. Inevitably some code that belongs in the domain model ends up in the GUI classes. So, which way do you design/develop your code? Why? GUI first. User interaction is paramount. Domain first. I need to make sure the system is correct before we put a UI on it. There's pros and cons for either approach. Domain model fits in there with crystal cathedrals and pie in the sky. GUI fits in there with quick and dirty (sometimes really dirty). And for an added bonus: How do you make sure the code is maintainable?

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