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  • Upcoming EBS Webcasts for June, July, August 2012

    - by user793553
    See the following upcoming webcasts for June, July and August 2012. Flag Doc ID 740966.1 as a favourite, to keep up to date with latest advisor schedule. Additionally, see Doc ID 740964.1 for access to all archived advisor webcasts Oracle E-Business Suite Oracle E-Business Suite Title Date Summary None at this time.     EBS Agile Title Date Summary None at this time.     EBS Applications Technologies Group (ATG) Title Date Summary EBS – OAM Tuning and Monitoring EMEA July 10, 2012 Abstract EBS – OAM Tuning and Monitoring US July 11, 2012 Abstract Workflow Analyzer Followup EMEA July 24, 2012 Abstract Workflow Analyzer Followup US July 25, 2012 Abstract EBS CRM & Industries Title Date Summary None at this time.     EBS Financials Title Date Summary EBS Fixed Assets: Achieve Success Using Proactive Tools For Fixed Assets Support July 10, 2012 Abstract Overview and Flow of Oracle Project Resource Management July 17, 2012 Abstract Leveraging My Oracle Support To Increase Knowledge July 30, 2012 Abstract EBS HCM (HRMS) Title Date Summary Oracle Time and Labor (OTL) Rollback Functionality Session 1 July 25, 2012 Abstract Oracle Time and Labor (OTL) Rollback Functionality Session 2 July 25, 2012 Abstract EBS Manufacturing Title Date Summary Using Personalization in Oracle eAM June 21, 2012 Abstract OM Guided Resolutions - Finding Known Resolutions Easily July 17, 2012 Abstract Material Move Orders Flow July 25, 2012 Abstract Diagnosing Signal 11 Issues In ASCP Planning August 9, 2012 Abstract Interface Trip Stop - Best Practices and Debugging August 21, 2012 Abstract EBS Procurement Title Date Summary Punchout in iProcurement June 26, 2012 Abstract

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  • My Feelings About Microsoft Surface

    - by Valter Minute
    Advice: read the title carefully, I’m talking about “feelings” and not about advanced technical points proved in a scientific and objective way I still haven’t had a chance to play with a MS Surface tablet (I would love to, of course) and so my ideas just came from reading different articles on the net and MS official statements. Remember also that the MVP motto begins with “Independent” (“Independent Experts. Real World Answers.”) and this is just my humble opinion about a product and a technology. I know that, being an MS MVP you can be called an “MS-fanboy”, I don’t care, I hope that people can appreciate my opinion, even if it doesn’t match theirs. The “Surface” brand can be confusing for techies that knew the “original” surface concept but I think that will be a fresh new brand name for most of the people out there. But marketing department are here to confuse people… so I can understand this “recycle” of an existing name. So Microsoft is entering the hardware arena… for me this is good news. Microsoft developed some nice hardware in the past: the xbox, zune (even if the commercial success was quite limited) and, last but not least, the two arc mices (old and new model) that I use and appreciate. In the past Microsoft worked with OEMs and that model lead to good and bad things. Good thing (for microsoft, at least) is market domination by windows-based PCs that only in the last years has been reduced by the return of the Mac and tablets. Google is also moving in the hardware business with its acquisition of Motorola, and Apple leveraged his control of both the hardware and software sides to develop innovative products. Microsoft can scare OEMs and make them fly away from windows (but where?) or just lead the pack, showing how devices should be designed to compete in the market and bring back some of the innovation that disappeared from recent PC products (look at the shelves of your favorite electronics store and try to distinguish a laptop between the huge mass of anonymous PCs on displays… only Macs shine out there…). Having to compete with MS “official” hardware will force OEMs to develop better product and bring back some real competition in a market that was ruled only by prices (the lower the better even when that means low quality) and no innovative features at all (when it was the last time that a new PC surprised you?). Moving into a new market is a big and risky move, but with Windows 8 Microsoft is playing a crucial move for its future, trying to be back in the innovation run against apple and google. MS can’t afford to fail this time. I saw the new devices (the WinRT and Pro) and the specifications are scarce, misleading and confusing. The first impression is that the device looks like an iPad with a nice keyboard cover… Using “HD” and “full HD” to define display resolution instead of using the real figures and reviving the “ClearType” brand (now dead on Win8 as reported here and missed by people who hate to read text on displays, like myself) without providing clear figures (couldn’t you count those damned pixels?) seems to imply that MS was caught by surprise by apple recent “retina” displays that brought very high definition screens on tablets.Also there are no specifications about the processors used (even if some sources report NVidia Tegra for the ARM tablet and i5 for the x86 one) and expected battery life (a critical point for tablets and the point that killed Windows7 x86 based tablets). Also nothing about the price, and this will be another critical point because other platform out there already provide lots of applications and have a good user base, if MS want to enter this market tablets pricing must be competitive. There are some expansion ports (SD and USB), so no fixed storage model (even if the specs talks about 32-64GB for RT and 128-256GB for pro). I like this and don’t like the apple model where flash memory (that it’s dirt cheap used in thumdrives or SD cards) is as expensive as gold (or cocaine to have a more accurate per gram measurement) when mounted inside a tablet/phone. For big files you’ll be able to use external media and an SD card could be used to store files that don’t require super-fast SSD-like access times, I hope. To be honest I really don’t like the marketplace model and the limitation of Windows RT APIs (no local database? from a company that based a good share of its success on VB6+Access!) and lack of desktop support on the ARM (even if the support is here and has been used to port office). It’s a step toward the consumer market (where competitors are making big money), but may impact enterprise (and embedded) users that may not appreciate Windows 8 new UI or the limitations of the new app model (if you aren’t connected you are dead ). Not having compatibility with the desktop will require brand new applications and honestly made all the CPU cycles spent to convert .NET IL into real machine code in the past like a huge waste of time… as soon as a new processor architecture is supported by Windows you still have to rewrite part of your application (and MS is pushing HTML5+JS and native code more than .NET in my perception). On the other side I believe that the development experience provided by Visual Studio is still miles (or kilometres) ahead of the competition and even the all-uppercase menu of VS2012 hasn’t changed this situation. The new metro UI got mixed reviews. On my side I should say that is very pleasant to use on a touch screen, I like the minimalist design (even if sometimes is too minimal and hides stuff that, in my opinion, should be visible) but I should also say that using it with mouse and keyboard is like trying to pick your nose with boxing gloves… Metro is also very interesting for embedded devices where touch screen usage is quite common and where having an application taking all the screen is the norm. For devices like kiosks, vending machines etc. this kind of UI can be a great selling point. I don’t need a new tablet (to be honest I’m pretty happy with my wife’s iPad and with my PC), but I may change my opinion after having a chance to play a little bit with those new devices and understand what’s hidden under all this mysterious and generic announcements and specifications!

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  • Clock drift even though NTPD running

    - by droffo
    I'm having a problem with the clock drifting on my PC. I'M running Ubuntu 10.10 on an somewhat crusty IBM e-server (1.5GB RAM, 2.4GHz CPU) ntpd is running (started at run level 2) servers are defined: server 1.us.pool.ntp.org server 2.us.pool.ntp.org server 3.us.pool.ntp.org server time.nrc.ca server ntp1.cmc.ec.gc.ca server ntp2.cmc.ec.gc.ca server wuarchive.wustl.edu server clock.psu.edu Looking at the log file, it would seem that the ntp daemon is running, but the system clock never seems to be set, however. If I manually set the time from a Casio "atomic" watch, the date/time displayed by the Clock applet drifts out of sync over time. Looking at the log file (below) it would seem the ntp daemon started ok and is running. So I am totally flummoxed right now :-( Here's a copy of my ntp.log file.

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  • Why do we keep using CSV?

    - by Stephen
    Why do we keep using CSV? I recently made a shift to working the health domain and despite the wonderful work in data transfer standards, all data transfer is in CSV, both for reporting to external organisations, and for data migrations when implementing new systems. Unfortunately the use of CSV is the cause of the endless repetition of the same stupid errors, with the same waste of developer time. (bad escaping, failing to handle null fields etc.) I know we can do better, and anything between JSON and XML (depending on the instance) would be fine. (Most of the time this is data going from one MS SQLserver 2005 to another!) I feel as if each time I see this happening I am literally watching one developer waste anothers time. So why do we keep shafting each other? When will we stop?

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  • Best way to handle realtime melee AI in authoritative network environment

    - by PrimeDerektive
    So i've been working on a multiplayer game for a bit; it's a co-op action RPG with real-time combat. If you've seen or played TERA, I'd say it's comparable to that, but not an MMO, heh. I'm currently handling the AI units authoritatively, the server calculates their pathing, movement, and pursue/attack logic, and syncs the movement to the clients 15x per second, and the state changes when they happen. When I emulate 200ms ping, though, the client can perceive being out of range to an AI's attack, but still take the hit, because on the server he hadn't moved that far yet. This also plays hell with my real-time blocking. I don't really want to allow the clients to be allowed to say "that was out of range" or "I blocked that", but I'm not really sure how else to handle it.

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  • Unity3D - Android pause screen - double click issue

    - by user3666251
    I made a pause script for the game im developing for android. I added the script to the GUITexture I created and placed on the top right side of the screen.The issue stands at the part where if the player clicks the pause button then clicks resume then he wants to pause the game again.When he clicks pause the second time the buttons dont show up unless he clicks again. This is the script : #pragma strict var paused = false; var isButtonVisible : boolean = true; function OnMouseDown(){ this.paused = !this.paused; Time.timeScale = 0; isButtonVisible = true; } function OnGUI(){ if ( isButtonVisible ) { if(this.paused){ if (GUI.Button(Rect(Screen.width/2-100,Screen.height/2+3,200,50),"Restart")){ Application.LoadLevel(Application.loadedLevel); Time.timeScale = 1; isButtonVisible = false; } if (GUI.Button(Rect(Screen.width/2-100,Screen.height/2-50,200,50),"Resume")){ Time.timeScale = 1; isButtonVisible = false; } // Insert the rest of the pause menu logic if (GUI.Button(Rect(Screen.width/2-100,Screen.height/2+56,200,50),"Main Menu")){ Application.LoadLevel ("MainMenu"); isButtonVisible = false; Time.timeScale = 1; } } } } Thank you.

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  • Problems building clamcour

    - by user10778
    Hello People, when i try to install clamcour from terminal, it gives me this error, somebody can help me? calmcourdir# ./configure checking for libraries containing socket functions... -lc checking for socket... yes checking for bind... yes checking for listen... yes checking for accept... yes checking for shutdown... yes checking for socklen_t... yes checking for struct sockaddr_un.sun_len... no System log functions checking syslog.h usability... yes checking syslog.h presence... yes checking for syslog.h... yes checking for openlog... yes checking for syslog... yes checking for closelog... yes Time functions checking whether time.h and sys/time.h may both be included... yes checking whether struct tm is in sys/time.h or time.h... time.h checking for localtime_r... yes checking for strftime... yes checking for unistd.h... (cached) yes checking limits.h usability... yes checking limits.h presence... yes checking for limits.h... yes checking for sysconf... yes BZip2 support checking bzlib.h usability... no checking bzlib.h presence... no checking for bzlib.h... no checking for BZ2_bzWriteOpen in -lbz2... no GZip support checking zlib.h usability... no checking zlib.h presence... no checking for zlib.h... no checking for gzopen in -lz... no LibClamAV support checking for /usr/bin/clamav-config... no checking for /usr/local/bin/courier-config... no checking for /usr/clamav/bin/clamav-config... no checking for /usr/local/clamav/bin/clamav-config... no ./configure: line 25234: : command not found configure: error: Cannot find clamav-config

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  • How is Sencha Touch performing on Android in practice ?

    - by Vidar Vestnes
    Hi I'm just about to start a project using Sencha Touch, and just done some minor testing on my HTC desire device. All tutorial videos at Vimeo seems to be using an iPhone emulator running on a Mac. Im not sure how fast this emulator is compared to a real iPhone device or even an real Android device, but from what i have experienced, it seems that my HTC desire is not performing that nicly as this emulator. All animations (sliding, fading, etc) seems abit laggy. You can easily notice that the FPS is much less than on the Vimeo videos. HTC desire is a relativly new and modern Android 2.2 phone, running with decent hardware, so im wondering if Sencha Touch is "ready" for the Android platform. Anybody with practical experience with Android and Sencha Touch ?

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  • Why does Google Analytics show false referrals?

    - by Peter Merrill
    Ever since Google revamped their Analytics interface I've been noticing a weird "bug" while viewing the "Real-Time" overview area. From this area I can obviously see live stats of visitors to my website but when I visit my website by opening a new tab (Chrome) and manually visit website the real time stats sometimes look like the image linked below. http://i.stack.imgur.com/mfniY.png Is there any reason why Google is saying that I was referred by Stack Overflow when I'm visiting my website from a new tab? Could this be something do to with how I installed the analytics on my site or could this be an issue with browser cookies? Have anyone else noticed this? I am mainly concerned about this because in the standard reporting area of my Analytics panel my referral stats are getting thrown off every time I visit my own website.

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  • CodePlex Daily Summary for Sunday, August 26, 2012

    CodePlex Daily Summary for Sunday, August 26, 2012Popular ReleasesPhysics Helper XAML: Physics Helper XAML 1.1.0.0: This release supports creation of 2D Physics apps for Windows 8 RTM, Windows Phone 7.1 development, and Silverlight 5. It includes source code and samples in three separate solutions.TouchInjector: TouchInjector 1.0: Version 1.0BlackJumboDog: Ver5.7.1: 2012.08.25 Ver5.7.1 (1)?????·?????LING?????????????? (2)SMTP???(????)????、?????\?????????????????????Peulot Heshbon: Peulot Heshbon version 3.0.0: Available quizzes:Plus for Natural, Real and fragments Minus for Natural, Real and fragments Multiplication for Natural, Real and fragments Divide for Natural, Real and fragments Random for Natural, Real and fragments Compare 2 percentages Compare 2 fragments (Just for easy difficulty) Check if a number can be divided with another number exactly. Available Languages:Hebrew English Russian What's NewAdded new quiz: Compare 2 fragments. It is available only if you are in Eas...Visual Studio Team Foundation Server Branching and Merging Guide: v2 - Visual Studio 2012: Welcome to the Branching and Merging Guide Quality-Bar Details Documentation has been reviewed by Visual Studio ALM Rangers Documentation has been through an independent technical review Documentation has been reviewed by the quality and recording team All critical bugs have been resolved Known Issues / Bugs Spelling, grammar and content revisions are in progress. Hotfix will be published.Microsoft Ajax Minifier: Microsoft Ajax Minifier 4.62: Fix for issue #18525 - escaped characters in CSS identifiers get double-escaped if the character immediately after the backslash is not normally allowed in an identifier. fixed symbol problem with nuget package. 4.62 should have nuget symbols available again.nopCommerce. Open source shopping cart (ASP.NET MVC): nopcommerce 2.65: As some of you may know we were planning to release version 2.70 much later (the end of September). But today we have to release this intermediate version (2.65). It fixes a critical issue caused by a third-party assembly when running nopCommerce on a server with .NET 4.5 installed. No major features have been introduced with this release as our development efforts were focused on further enhancements and fixing bugs. To see the full list of fixes and changes please visit the release notes p...MyRouter (Virtual WiFi Router): MyRouter 1.2.9: . Fix: Some missing changes for fixing the window subclassing crash. · Fix: fixed bug when Run MyRouter at the first Time. · Fix: Log File · Fix: improve performance speed application · fix: solve some Exception.eel Browser: eel 1.1.0.41 beta: Improved UI New features Bug fixesDynamics CRM 2011 Dummy Entity: First Release: This has been tested on CRM 2011 RU8 On-Premise IFD. Known Issue: The Test Dummy CRM page load event may throw an exception loading the first time as the iframe may not have finished loading. I have not been able to get the iframe OnReadyStateChange event to fire. But it is only a sample anyway. The zip file contains: Dummy Entity Visual studio solution. Test Dummy Visual Studio solution. Dummy Entity CRM Solution Test Dummy CRM Solution Installation: Unzip and import the CRM Solutions...Private cloud DMS: Essential server-client full package: Requirements: - SQL server >= 2008 (minimal Express - for Essential recommended) - .NET 4.0 (Server) - .NET 4.0 Client profile (Client) This version allow: - full file system functionality Restrictions: - Maximum 2 parallel users - No share spaces - No hosted business groups - No digital sign functionality - No ActiveDirectory connector - No Performance cache - No workflow - No messagingJavaScript Prototype Extensions: Release 1.1.0.0: Release 1.1.0.0 Add prototype extension for object. Add prototype extension for array.Glyphx: Version 1.2: This release includes the SdlDotNet.dll dependency in the setup, which you will need.TFS Project Test Migrator: TestPlanMigration v1.0.0: Release 1.0.0 This first version do not create the test cases in the target project because the goal was to restore a Test Plan + Test Suite hierarchy after a manual user deletion without restoring all the Project Collection Database. As I discovered, deleting a Test Plan will do the following : - Delete all TestSuiteEntry (the link between a Test Suite node and a Test Case) - Delete all TestSuite (the nodes in the test hierarchy), including root TestSuite - Delete the TestPlan Test c...ERPStore eCommerce FrontOffice: ERPStore.Core V4.0.0.2 MVC4 RTM: ERPStore.Core V4.0.0.2 MVC4 RTM (Code Source)ZXing.Net: ZXing.Net 0.8.0.0: sync with rev. 2393 of the java version improved API, direct support for multiple barcode decoding, wrapper for barcode generating many other improvements and fixes encoder and decoder command line clients demo client for emguCV dev documentation startedScintillaNET: ScintillaNET 2.5.1: This release has been built from the 2.5 branch. Issues closed: Issue # Title 32524 32524 32550 32550 32552 32552 25148 25148 32449 32449 32551 32551 32711 32711 MFCMAPI: August 2012 Release: Build: 15.0.0.1035 Full release notes at SGriffin's blog. If you just want to run the MFCMAPI or MrMAPI, get the executables. If you want to debug them, get the symbol files and the source. The 64 bit builds will only work on a machine with Outlook 2010 64 bit installed. All other machines should use the 32 bit builds, regardless of the operating system. Facebook BadgeDocument.Editor: 2013.2: Whats new for Document.Editor 2013.2: New save as Html document Improved Traslate support Minor Bug Fix's, improvements and speed upsPulse: Pulse Beta 5: Whats new in this release? Well to start with we now have Wallbase.cc Authentication! so you can access favorites or NSFW. This version requires .NET 4.0, you probably already have it, but if you don't it's a free and easy download from Microsoft. Pulse can bet set to start on Windows startup now too. The Wallpaper setter has settings now, so you can change the background color of the desktop and the Picture Position (Tile/Center/Fill/etc...) I've switched to Windows Forms instead of WPF...New Projects508 Compliance Validator: This tool checks aspx and ascx pages against 508 Accessibilty guidelines and also allows you to add your own rules.BF for WP: BF for WP is a visual Brainfuck interpter for Windows Phone.Climate Control: App lets you vote on whether you're too hot or too cold so the dummy next to the air con controls can adjust the thermostat.Custom Captcha Plugin for Kooboo CMS for adding content or sending feedback: Custom Captcha Plugin for Kooboo CMS for adding content or sending feedbackGalleryDownloader: This project takes aim on downloading free photogalleries through the Internet. Highly Maintainable Web Services: The Highly Maintainable Web Services project is a reference architecture application for .NET that demonstrates how to build highly maintainable web services.Its.Validation: A C# DSL for writing rules in a composable, functional style.Kaku by wifi: The projects purpose: Make your phone a part of your house hold by being able to control certail elektric devices with your phone such as, light, electric curtaLogin with Google in ASP.Net MVC3 & Get data from Google User: ASP.Net developer can use this code: asp.net mvc3 web project which contains login with google and pull data from user's google accountMabiCommerce: MabiCommerce is an advanced Commerce Calculator for the MMORPG Mabinogi.Mapture the FLAG: A location based game for wp7mn: sumSharePoint 2010: SharePoint 2010 utilitiesSHIORI.NET: ???SHIORI????????????????????Temp and Stress: Tieni sotto controllo le temperature della tua CPU e effettua Stress Test e Benchmark!VisiblityControl – An Alternative to Converters: A templated content control hosting to remove the pain of using the BooleanToVisibilityConverter. The property IsTrue determines what is shown.Whatsnexx Integration for Orchard CMS: Orchard Whatsnexx makes it easier for Orchard users to send an event to the Whatsnexx Ticket Bus service API, of the Whatsnexx GatewayWINRT \ Metro Store \ open marketing solution: This project is aimed at creating a public shopping cart, that is available to all windows 8 users free. products are screened added by administrators

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  • PCLinuxOS 2010 (KDE) Review

    <b>Desktop Linux Reviews:</b> "The last time I looked at PCLinuxOS was back in 2009 when I was working full-time for ExtremeTech. There's a new release out and it's a good time for a review of it here on DLR."

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  • Cloud to On-Premise Connectivity Patterns

    - by Rajesh Raheja
    Do you have a requirement to convert an Opportunity in Salesforce.com to an Order/Quote in Oracle E-Business Suite? Or maybe you want the creation of an Oracle RightNow Incident to trigger an on-premise Oracle E-Business Suite Service Request creation for RMA and Field Scheduling? If so, read on. In a previous blog post, I discussed integrating TO cloud applications, however the use cases above are the reverse i.e. receiving data FROM cloud applications (SaaS) TO on-premise applications/databases that sit behind a firewall. Oracle SOA Suite is assumed to be on-premise with with Oracle Service Bus as the mediation and virtualization layer. The main considerations for the patterns are are security i.e. shielding enterprise resources; and scalability i.e. minimizing firewall latency. Let me use an analogy to help visualize the patterns: the on-premise system is your home - with your most valuable possessions - and the SaaS app is your favorite on-line store which regularly ships (inbound calls) various types of parcels/items (message types/service operations). You need the items at home (on-premise) but want to safe guard against misguided elements of society (internet threats) who may masquerade as postal workers and vandalize property (denial of service?). Let's look at the patterns. Pattern: Pull from Cloud The on-premise system polls from the SaaS apps and picks up the message instead of having it delivered. This may be done using Oracle RightNow Object Query Language or SOAP APIs. This is particularly suited for certain integration approaches wherein messages are trickling in, can be centralized and batched e.g. retrieving event notifications on an hourly schedule from the Oracle Messaging Service. To compare this pattern with the home analogy, you are avoiding any deliveries to your home and instead go to the post office/UPS/Fedex store to pick up your parcel. Every time. Pros: On-premise assets not exposed to the Internet, firewall issues avoided by only initiating outbound connections Cons: Polling mechanisms may affect performance, may not satisfy near real-time requirements Pattern: Open Firewall Ports The on-premise system exposes the web services that needs to be invoked by the cloud application. This requires opening up firewall ports, routing calls to the appropriate internal services behind the firewall. Fusion Applications uses this pattern, and auto-provisions the services on the various virtual hosts to secure the topology. This works well for service integration, but may not suffice for large volume data integration. Using the home analogy, you have now decided to receive parcels instead of going to the post office every time. A door mail slot cut out allows the postman can drop small parcels, but there is still concern about cutting new holes for larger packages. Pros: optimal pattern for near real-time needs, simpler administration once the service is provisioned Cons: Needs firewall ports to be opened up for new services, may not suffice for batch integration requiring direct database access Pattern: Virtual Private Networking The on-premise network is "extended" to the cloud (or an intermediary on-demand / managed service offering) using Virtual Private Networking (VPN) so that messages are delivered to the on-premise system in a trusted channel. Using the home analogy, you entrust a set of keys with a neighbor or property manager who receives the packages, and then drops it inside your home. Pros: Individual firewall ports don't need to be opened, more suited for high scalability needs, can support large volume data integration, easier management of one connection vs a multitude of open ports Cons: VPN setup, specific hardware support, requires cloud provider to support virtual private computing Pattern: Reverse Proxy / API Gateway The on-premise system uses a reverse proxy "API gateway" software on the DMZ to receive messages. The reverse proxy can be implemented using various mechanisms e.g. Oracle API Gateway provides firewall and proxy services along with comprehensive security, auditing, throttling benefits. If a firewall already exists, then Oracle Service Bus or Oracle HTTP Server virtual hosts can provide reverse proxy implementations on the DMZ. Custom built implementations are also possible if specific functionality (such as message store-n-forward) is needed. In the home analogy, this pattern sits in between cutting mail slots and handing over keys. Instead, you install (and maintain) a mailbox in your home premises outside your door. The post office delivers the parcels in your mailbox, from where you can securely retrieve it. Pros: Very secure, very flexible Cons: Introduces a new software component, needs DMZ deployment and management Pattern: On-Premise Agent (Tunneling) A light weight "agent" software sits behind the firewall and initiates the communication with the cloud, thereby avoiding firewall issues. It then maintains a bi-directional connection either with pull or push based approaches using (or abusing, depending on your viewpoint) the HTTP protocol. Programming protocols such as Comet, WebSockets, HTTP CONNECT, HTTP SSH Tunneling etc. are possible implementation options. In the home analogy, a resident receives the parcel from the postal worker by opening the door, however you still take precautions with chain locks and package inspections. Pros: Light weight software, IT doesn't need to setup anything Cons: May bypass critical firewall checks e.g. virus scans, separate software download, proliferation of non-IT managed software Conclusion The patterns above are some of the most commonly encountered ones for cloud to on-premise integration. Selecting the right pattern for your project involves looking at your scalability needs, security restrictions, sync vs asynchronous implementation, near real-time vs batch expectations, cloud provider capabilities, budget, and more. In some cases, the basic "Pull from Cloud" may be acceptable, whereas in others, an extensive VPN topology may be well justified. For more details on the Oracle cloud integration strategy, download this white paper.

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  • Cloud to On-Premise Connectivity Patterns

    - by Rajesh Raheja
    Do you have a requirement to convert an Opportunity in Salesforce.com to an Order/Quote in Oracle E-Business Suite? Or maybe you want the creation of an Oracle RightNow Incident to trigger an on-premise Oracle E-Business Suite Service Request creation for RMA and Field Scheduling? If so, read on. In a previous blog post, I discussed integrating TO cloud applications, however the use cases above are the reverse i.e. receiving data FROM cloud applications (SaaS) TO on-premise applications/databases that sit behind a firewall. Oracle SOA Suite is assumed to be on-premise with with Oracle Service Bus as the mediation and virtualization layer. The main considerations for the patterns are are security i.e. shielding enterprise resources; and scalability i.e. minimizing firewall latency. Let me use an analogy to help visualize the patterns: the on-premise system is your home - with your most valuable possessions - and the SaaS app is your favorite on-line store which regularly ships (inbound calls) various types of parcels/items (message types/service operations). You need the items at home (on-premise) but want to safe guard against misguided elements of society (internet threats) who may masquerade as postal workers and vandalize property (denial of service?). Let's look at the patterns. Pattern: Pull from Cloud The on-premise system polls from the SaaS apps and picks up the message instead of having it delivered. This may be done using Oracle RightNow Object Query Language or SOAP APIs. This is particularly suited for certain integration approaches wherein messages are trickling in, can be centralized and batched e.g. retrieving event notifications on an hourly schedule from the Oracle Messaging Service. To compare this pattern with the home analogy, you are avoiding any deliveries to your home and instead go to the post office/UPS/Fedex store to pick up your parcel. Every time. Pros: On-premise assets not exposed to the Internet, firewall issues avoided by only initiating outbound connections Cons: Polling mechanisms may affect performance, may not satisfy near real-time requirements Pattern: Open Firewall Ports The on-premise system exposes the web services that needs to be invoked by the cloud application. This requires opening up firewall ports, routing calls to the appropriate internal services behind the firewall. Fusion Applications uses this pattern, and auto-provisions the services on the various virtual hosts to secure the topology. This works well for service integration, but may not suffice for large volume data integration. Using the home analogy, you have now decided to receive parcels instead of going to the post office every time. A door mail slot cut out allows the postman can drop small parcels, but there is still concern about cutting new holes for larger packages. Pros: optimal pattern for near real-time needs, simpler administration once the service is provisioned Cons: Needs firewall ports to be opened up for new services, may not suffice for batch integration requiring direct database access Pattern: Virtual Private Networking The on-premise network is "extended" to the cloud (or an intermediary on-demand / managed service offering) using Virtual Private Networking (VPN) so that messages are delivered to the on-premise system in a trusted channel. Using the home analogy, you entrust a set of keys with a neighbor or property manager who receives the packages, and then drops it inside your home. Pros: Individual firewall ports don't need to be opened, more suited for high scalability needs, can support large volume data integration, easier management of one connection vs a multitude of open ports Cons: VPN setup, specific hardware support, requires cloud provider to support virtual private computing Pattern: Reverse Proxy / API Gateway The on-premise system uses a reverse proxy "API gateway" software on the DMZ to receive messages. The reverse proxy can be implemented using various mechanisms e.g. Oracle API Gateway provides firewall and proxy services along with comprehensive security, auditing, throttling benefits. If a firewall already exists, then Oracle Service Bus or Oracle HTTP Server virtual hosts can provide reverse proxy implementations on the DMZ. Custom built implementations are also possible if specific functionality (such as message store-n-forward) is needed. In the home analogy, this pattern sits in between cutting mail slots and handing over keys. Instead, you install (and maintain) a mailbox in your home premises outside your door. The post office delivers the parcels in your mailbox, from where you can securely retrieve it. Pros: Very secure, very flexible Cons: Introduces a new software component, needs DMZ deployment and management Pattern: On-Premise Agent (Tunneling) A light weight "agent" software sits behind the firewall and initiates the communication with the cloud, thereby avoiding firewall issues. It then maintains a bi-directional connection either with pull or push based approaches using (or abusing, depending on your viewpoint) the HTTP protocol. Programming protocols such as Comet, WebSockets, HTTP CONNECT, HTTP SSH Tunneling etc. are possible implementation options. In the home analogy, a resident receives the parcel from the postal worker by opening the door, however you still take precautions with chain locks and package inspections. Pros: Light weight software, IT doesn't need to setup anything Cons: May bypass critical firewall checks e.g. virus scans, separate software download, proliferation of non-IT managed software Conclusion The patterns above are some of the most commonly encountered ones for cloud to on-premise integration. Selecting the right pattern for your project involves looking at your scalability needs, security restrictions, sync vs asynchronous implementation, near real-time vs batch expectations, cloud provider capabilities, budget, and more. In some cases, the basic "Pull from Cloud" may be acceptable, whereas in others, an extensive VPN topology may be well justified. For more details on the Oracle cloud integration strategy, download this white paper.

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  • Comparing Apples and Pairs

    - by Tony Davis
    A recent study, High Costs and Negative Value of Pair Programming, by Capers Jones, pulls no punches in its assessment of the costs-to- benefits ratio of pair programming, two programmers working together, at a single computer, rather than separately. He implies that pair programming is a method rushed into production on a wave of enthusiasm for Agile or Extreme Programming, without any real regard for its effectiveness. Despite admitting that his data represented a far from complete study of the economics of pair programming, his conclusions were stark: it was 2.5 times more expensive, resulted in a 15% drop in productivity, and offered no significant quality benefits. The author provides a more scientific analysis than Jon Evans’ Pair Programming Considered Harmful, but the theme is the same. In terms of upfront-coding costs, pair programming is surely more expensive. The claim of productivity loss is dubious and contested by other studies. The third claim, though, did surprise me. The author’s data suggests that if both the pair and the individual programmers employ static code analysis and testing, then there is no measurable difference in the resulting code quality, in terms of defects per function point. In other words, pair programming incurs a massive extra cost for no tangible return in investment. There were, inevitably, many criticisms of his data and his conclusions, a few of which are persuasive. Firstly, that the driver/observer model of pair programming, on which the study bases its findings, is far from the most effective. For example, many find Ping-Pong pairing, based on use of test-driven development, far more productive. Secondly, that it doesn’t distinguish between “expert” and “novice” pair programmers– that is, independently of other programming skills, how skilled was an individual at pair programming. Thirdly, that his measure of quality is too narrow. This point rings true, certainly at Red Gate, where developers don’t pair program all the time, but use the method in short bursts, while tackling a tricky problem and needing a fresh perspective on the best approach, or more in-depth knowledge in a particular domain. All of them argue that pair programming, and collective code ownership, offers significant rewards, if not in terms of immediate “bug reduction”, then in removing the likelihood of single points of failure, and improving the overall quality and longer-term adaptability/maintainability of the design. There is also a massive learning benefit for both participants. One developer told me how he once worked in the same team over consecutive summers, the first time with no pair programming and the second time pair-programming two-thirds of the time, and described the increased rate of learning the second time as “phenomenal”. There are a great many theories on how we should develop software (Scrum, XP, Lean, etc.), but woefully little scientific research in their effectiveness. For a group that spends so much time crunching other people’s data, I wonder if developers spend enough time crunching data about themselves. Capers Jones’ data may be incomplete, but should cause a pause for thought, especially for any large IT departments, supporting commerce and industry, who are considering pair programming. It certainly shouldn’t discourage teams from exploring new ways of developing software, as long as they also think about how to gather hard data to gauge their effectiveness.

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  • How do I improve my problem-solving ability

    - by gcc
    How can I improve my problem-solving ability? Every one says same thing "a real programmer knows how to handle real problem", but they forget how they learn this ability, or where (I know in school, no one gives us any ability, of course in my opinion). If you have any idea except above ones, feel free when you give your advice solve more problems do more exercises, write code, search google then write more ... For me, my question is like "Use complex/known library instead of using your own." In other words, I want your experience, book recommendation, web page on problem solving

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  • Are the National Computer Science Academy certifications worth it?

    - by Horacio Nuñez
    Hi to every one. I have a question regarding the real value of having NCSA's certifications. Today I reach their site and I easily passed the JavaScript certification within minutes, but I never reach questions related to Literal Javascript Notation (Json), closures or browser specific apis. This facts let me to doubt a bit of the real value of the test (and the proper certification you can have if you pay them $34), but maybe Im wrong and just earned a respected certification within the States for easy questions... in wich case I can spend some time doing other certifications on the same site. Did you have an NCSA certification and think is worth having it in your resume, or you know of a better certification program? thanks in advance, and looking forward to see your considerations.

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  • Developing Schema Compare for Oracle (Part 6): 9i Query Performance

    - by Simon Cooper
    All throughout the EAP and beta versions of Schema Compare for Oracle, our main request was support for Oracle 9i. After releasing version 1.0 with support for 10g and 11g, our next step was then to get version 1.1 of SCfO out with support for 9i. However, there were some significant problems that we had to overcome first. This post will concentrate on query execution time. When we first tested SCfO on a 9i server, after accounting for various changes to the data dictionary, we found that database registration was taking a long time. And I mean a looooooong time. The same database that on 10g or 11g would take a couple of minutes to register would be taking upwards of 30 mins on 9i. Obviously, this is not ideal, so a poke around the query execution plans was required. As an example, let's take the table population query - the one that reads ALL_TABLES and joins it with a few other dictionary views to get us back our list of tables. On 10g, this query takes 5.6 seconds. On 9i, it takes 89.47 seconds. The difference in execution plan is even more dramatic - here's the (edited) execution plan on 10g: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 108K| 939 || 1 | SORT ORDER BY | | 108K| 939 || 2 | NESTED LOOPS OUTER | | 108K| 938 ||* 3 | HASH JOIN RIGHT OUTER | | 103K| 762 || 4 | VIEW | ALL_EXTERNAL_LOCATIONS | 2058 | 3 ||* 20 | HASH JOIN RIGHT OUTER | | 73472 | 759 || 21 | VIEW | ALL_EXTERNAL_TABLES | 2097 | 3 ||* 34 | HASH JOIN RIGHT OUTER | | 39920 | 755 || 35 | VIEW | ALL_MVIEWS | 51 | 7 || 58 | NESTED LOOPS OUTER | | 39104 | 748 || 59 | VIEW | ALL_TABLES | 6704 | 668 || 89 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2025 | 5 || 106 | VIEW | ALL_PART_TABLES | 277 | 11 |------------------------------------------------------------------------------- And the same query on 9i: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 16P| 55G|| 1 | SORT ORDER BY | | 16P| 55G|| 2 | NESTED LOOPS OUTER | | 16P| 862M|| 3 | NESTED LOOPS OUTER | | 5251G| 992K|| 4 | NESTED LOOPS OUTER | | 4243M| 2578 || 5 | NESTED LOOPS OUTER | | 2669K| 1440 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 ||* 50 | VIEW PUSHED PREDICATE | ALL_TAB_COMMENTS | 2043 | ||* 66 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_TABLES | 1777K| ||* 80 | VIEW PUSHED PREDICATE | ALL_EXTERNAL_LOCATIONS | 1744K| ||* 96 | VIEW | ALL_PART_TABLES | 852K| |------------------------------------------------------------------------------- Have a look at the cost column. 10g's overall query cost is 939, and 9i is 55,000,000,000 (or more precisely, 55,496,472,769). It's also having to process far more data. What on earth could be causing this huge difference in query cost? After trawling through the '10g New Features' documentation, we found item 1.9.2.21. Before 10g, Oracle advised that you do not collect statistics on data dictionary objects. From 10g, it advised that you do collect statistics on the data dictionary; for our queries, Oracle therefore knows what sort of data is in the dictionary tables, and so can generate an efficient execution plan. On 9i, no statistics are present on the system tables, so Oracle has to use the Rule Based Optimizer, which turns most LEFT JOINs into nested loops. If we force 9i to use hash joins, like 10g, we get a much better plan: -------------------------------------------------------------------------------| Id | Operation | Name | Bytes | Cost |-------------------------------------------------------------------------------| 0 | SELECT STATEMENT | | 7587K| 3704 || 1 | SORT ORDER BY | | 7587K| 3704 ||* 2 | HASH JOIN OUTER | | 7587K| 822 ||* 3 | HASH JOIN OUTER | | 5262K| 616 ||* 4 | HASH JOIN OUTER | | 2980K| 465 ||* 5 | HASH JOIN OUTER | | 710K| 432 ||* 6 | HASH JOIN OUTER | | 398K| 302 || 7 | VIEW | ALL_TABLES | 342K| 276 || 29 | VIEW | ALL_MVIEWS | 51 | 20 || 50 | VIEW | ALL_PART_TABLES | 852K| 104 || 78 | VIEW | ALL_TAB_COMMENTS | 2043 | 14 || 93 | VIEW | ALL_EXTERNAL_LOCATIONS | 1744K| 31 || 106 | VIEW | ALL_EXTERNAL_TABLES | 1777K| 28 |------------------------------------------------------------------------------- That's much more like it. This drops the execution time down to 24 seconds. Not as good as 10g, but still an improvement. There are still several problems with this, however. 10g introduced a new join method - a right outer hash join (used in the first execution plan). The 9i query optimizer doesn't have this option available, so forcing a hash join means it has to hash the ALL_TABLES table, and furthermore re-hash it for every hash join in the execution plan; this could be thousands and thousands of rows. And although forcing hash joins somewhat alleviates this problem on our test systems, there's no guarantee that this will improve the execution time on customers' systems; it may even increase the time it takes (say, if all their tables are partitioned, or they've got a lot of materialized views). Ideally, we would want a solution that provides a speedup whatever the input. To try and get some ideas, we asked some oracle performance specialists to see if they had any ideas or tips. Their recommendation was to add a hidden hook into the product that allowed users to specify their own query hints, or even rewrite the queries entirely. However, we would prefer not to take that approach; as well as a lot of new infrastructure & a rewrite of the population code, it would have meant that any users of 9i would have to spend some time optimizing it to get it working on their system before they could use the product. Another approach was needed. All our population queries have a very specific pattern - a base table provides most of the information we need (ALL_TABLES for tables, or ALL_TAB_COLS for columns) and we do a left join to extra subsidiary tables that fill in gaps (for instance, ALL_PART_TABLES for partition information). All the left joins use the same set of columns to join on (typically the object owner & name), so we could re-use the hash information for each join, rather than re-hashing the same columns for every join. To allow us to do this, along with various other performance improvements that could be done for the specific query pattern we were using, we read all the tables individually and do a hash join on the client. Fortunately, this 'pure' algorithmic problem is the kind that can be very well optimized for expected real-world situations; as well as storing row data we're not using in the hash key on disk, we use very specific memory-efficient data structures to store all the information we need. This allows us to achieve a database population time that is as fast as on 10g, and even (in some situations) slightly faster, and a memory overhead of roughly 150 bytes per row of data in the result set (for schemas with 10,000 tables in that means an extra 1.4MB memory being used during population). Next: fun with the 9i dictionary views.

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  • How do I maintain a really poorly written code base?

    - by onlineapplab.com
    Recently I got hired to work on existing web application because of NDA I'm not at liberty to disclose any details but this application is working online in sort of a beta testing stage before official launch. We have a few hundred users right now but this number is supposed to significantly increase after official launch. The application is written in PHP (but it is irrelevant to my question) and is running on a dual xeon processor standalone server with severe performance problems. I have seen a lot of bad PHP code but this really sets new standards, especially knowing how much time and money was invested in developing it. it is as badly coded as possible there is PHP, HTML, SQL mixed together and code is repeated whenever it is necessary (especially SQL queries). there are not any functions used, not mentioning any OOP there are four versions of the app (desktop, iPhone, Android + other mobile) each version has pretty much the same functionality but was created by copying the whole code base, so now there are some differences between each version and it is really hard to maintain the database is really badly designed, which is causing severe performance problems also for fixing some errors in PHP code there is a lot of database triggers used which are updating data on SELECT and on INSERT so any testing is a nightmare Basically, any sin of a bad programming you can imagine is there for example it is not only possible to use SQL injections in literally every place but you can log into app if you use a login which doesn't exist and an empty password. The team which created this app is not working on it any more and there is an outsourced team which suggested that there are some problems but was never willing to deal with the elephant in the room partially because they've got a very comfortable contract and partially due to lack of skills (just my opinion). My job was supposed to be fixing some performance problems and extending existing functionality but first thing I was asked to do was a review of the existing code base. I've made my review and it was quite a shock for the management but my conclusions were after some time finally confirmed by other programmers. Management made it clear that it is not possible to start rewriting this app from scratch (which in my opinion should be done). We have to maintain its operable state and at the same time fix performance errors and extend the functionality. My question is, as I don't want just to patch the existing code, how to transform this into properly written app while keeping the existing code working at the same time? My plan is: Unify four existing versions into common code base (fixing only most obvious errors). Redesign db and use triggers to populate it with data (so data will be maintained in two formats at the same time) All new functionality will be written as separate project. Step by step transfer existing functionality into the new project After some time everything will be in the new project Some explanation about #2, right now it is practically impossible to make any updates in existing db any change requires reviewing whole code and making changes in many places. Is such plan feasible at all? Another solution is to walk away and leave the headache to someone else.

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  • 2D vector graphic html5 framework

    - by Yury
    I trying to find html5 game framework by following criteria: 1)Real good performance. 2)Good support of vector graphic( objects which contains canvas elements -line, rec,bezierCurve etc.) 3)Easy port to mobile. Optional- Physics Engine. I found 1)Pixi.js- it looks like real good, but i didn't find any info about "vector objects" support. 2) i found "vector objects" support in paper.js I need something like these: http://paperjs.org/examples/chain/ and http://paperjs.org/examples/path-intersections/. But it looks like paper.js- not so good performance as pixi.js. And it is not game engine. Is there any good framework meets these requirements? P.S. I found similar question here Which free HTML5-based game engine meets these requirements?. But it was a long time ago. A lot of new things were created since 2011.

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  • Coherence Webcast for Developers July 11

    - by jeckels
    Coming on July 11th, we look forward to having you join us for a special Coherence webcast - just for developers! Want to learn how you, the developer, can make applications Big Data and Fast data ready? Want to be able to customize and manage your applications and services to provide real-time data and processing with ease? Then this webcast is for you. Coherence Live Webcast Developers: Deploy Highly-Available Custom Services on Your Data Grid Products July 11, 10am Pacific Time >> Register now! <<  (of course, it's free)Join Brian Oliver of the Coherence team to see how you can create and deploy customized, highly-available services for your data grid, and how real-time data processing will allow you to provide unmatched end-user experiences. We look forward to having you join us.

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  • Is OO-programming really as important as hiring companies place it?

    - by ale
    I am just finishing my masters degree (in computing) and applying for jobs.. I've noticed many companies specifically ask for an understanding of object orientation. Popular interview questions are about inheritance, polymorphism, accessors etc. Is OO really that crucial? I even had an interview for a programming job in C and half the interview was OO. In the real world, developing real applications, is object orientation nearly always used? Are key features like polymorphism used A LOT? I think my question comes from one of my weaknesses.. although I know about OO.. I don't seem to be able to incorporate it a great deal into my programs. I would be really interested to get peoples' thoughts on this!

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  • Upgrading from Express Edition to Standard Edition

    - by TiborKaraszi
    Say you encounter an SQL Server which is Express Edition, and it really should have been some higher edition. Sounds familiar? It is common for me as a consultant to find plenty of SQL Servers at a customer's site. Many of the databases in these will be moved (typically using backup and restore) to a "real" SQL Server. But in some cases, this might not be desirable. You want to convert the whole instance, from Express to a "real" SQL Server edition. I'm attending a great SharePoint course for Daniel...(read more)

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  • excel 2010 search function?

    - by Tom
    can a cell A1:A200 be searched for a "name" then once found, imput the cell location into a formula? such as find "tom"(a1:a200), [found location at cell a22] IF(a22),=IF(MINUTE(Auto_Agent!G27)+(SECOND(Auto_Agent!G27))=0,"",(MINUTE(Auto_Agent!G27)*60+(SECOND(Auto_Agent!G27)))) the problem I'm having is each time I import data names can be in different cell locations depending on who is working that day. example: Agent: Tom 07:59:49 02:31:04 00:00:00 00:42:44 01:33:02 00:00:43 00:02:00 03:09:05 Avg Skillset Talk Time: 00:06:52 07:59:49 02:31:04 00:00:00 00:42:44 01:33:02 00:00:43 00:02:00 03:09:05 () 9/19/2012 Avg Skillset Talk Time: 00:06:52 07:59:49 02:31:04 00:00:00 00:42:44 01:33:02 00:00:43 00:02:00 03:09:05 Agent: Bill 07:59:49 02:31:04 00:00:00 00:42:44 01:33:02 00:00:43 00:02:00 03:09:05 Avg Skillset Talk Time: 00:06:52 07:59:49 02:31:04 00:00:00 00:42:44 01:33:02 00:00:43 00:02:00 03:09:05 () 9/19/2012 Avg Skillset Talk Time: 00:06:52 07:59:49 02:31:04 00:00:00 00:42:44 01:33:02 00:00:43 00:02:00 03:09:05

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  • Organization &amp; Architecture UNISA Studies &ndash; Chap 4

    - by MarkPearl
    Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users perspective the two most important characteristics of memory are… Capacity Performance – access time, memory cycle time, transfer rate The trade off for memory happens along three axis… Faster access time, greater cost per bit Greater capacity, smaller cost per bit Greater capacity, slower access time This leads to people using a tiered approach in their use of memory   As one goes down the hierarchy, the following occurs… Decreasing cost per bit Increasing capacity Increasing access time Decreasing frequency of access of the memory by the processor The use of two levels of memory to reduce average access time works in principle, but only if conditions 1 to 4 apply. A variety of technologies exist that allow us to accomplish this. Thus it is possible to organize data across the hierarchy such that the percentage of accesses to each successively lower level is substantially less than that of the level above. A portion of main memory can be used as a buffer to hold data temporarily that is to be read out to disk. This is sometimes referred to as a disk cache and improves performance in two ways… Disk writes are clustered. Instead of many small transfers of data, we have a few large transfers of data. This improves disk performance and minimizes processor involvement. Some data designed for write-out may be referenced by a program before the next dump to disk. In that case the data is retrieved rapidly from the software cache rather than slowly from disk. Cache Memory Principles Cache memory is substantially faster than main memory. A caching system works as follows.. When a processor attempts to read a word of memory, a check is made to see if this in in cache memory… If it is, the data is supplied, If it is not in the cache, a block of main memory, consisting of a fixed number of words is loaded to the cache. Because of the phenomenon of locality of references, when a block of data is fetched into the cache, it is likely that there will be future references to that same memory location or to other words in the block. Elements of Cache Design While there are a large number of cache implementations, there are a few basic design elements that serve to classify and differentiate cache architectures… Cache Addresses Cache Size Mapping Function Replacement Algorithm Write Policy Line Size Number of Caches Cache Addresses Almost all non-embedded processors support virtual memory. Virtual memory in essence allows a program to address memory from a logical point of view without needing to worry about the amount of physical memory available. When virtual addresses are used the designer may choose to place the cache between the MMU (memory management unit) and the processor or between the MMU and main memory. The disadvantage of virtual memory is that most virtual memory systems supply each application with the same virtual memory address space (each application sees virtual memory starting at memory address 0), which means the cache memory must be completely flushed with each application context switch or extra bits must be added to each line of the cache to identify which virtual address space the address refers to. Cache Size We would like the size of the cache to be small enough so that the overall average cost per bit is close to that of main memory alone and large enough so that the overall average access time is close to that of the cache alone. Also, larger caches are slightly slower than smaller ones. Mapping Function Because there are fewer cache lines than main memory blocks, an algorithm is needed for mapping main memory blocks into cache lines. The choice of mapping function dictates how the cache is organized. Three techniques can be used… Direct – simplest technique, maps each block of main memory into only one possible cache line Associative – Each main memory block to be loaded into any line of the cache Set Associative – exhibits the strengths of both the direct and associative approaches while reducing their disadvantages For detailed explanations of each approach – read the text book (page 148 – 154) Replacement Algorithm For associative and set associating mapping a replacement algorithm is needed to determine which of the existing blocks in the cache must be replaced by a new block. There are four common approaches… LRU (Least recently used) FIFO (First in first out) LFU (Least frequently used) Random selection Write Policy When a block resident in the cache is to be replaced, there are two cases to consider If no writes to that block have happened in the cache – discard it If a write has occurred, a process needs to be initiated where the changes in the cache are propagated back to the main memory. There are several approaches to achieve this including… Write Through – all writes to the cache are done to the main memory as well at the point of the change Write Back – when a block is replaced, all dirty bits are written back to main memory The problem is complicated when we have multiple caches, there are techniques to accommodate for this but I have not summarized them. Line Size When a block of data is retrieved and placed in the cache, not only the desired word but also some number of adjacent words are retrieved. As the block size increases from very small to larger sizes, the hit ratio will at first increase because of the principle of locality, which states that the data in the vicinity of a referenced word are likely to be referenced in the near future. As the block size increases, more useful data are brought into cache. The hit ratio will begin to decrease as the block becomes even bigger and the probability of using the newly fetched information becomes less than the probability of using the newly fetched information that has to be replaced. Two specific effects come into play… Larger blocks reduce the number of blocks that fit into a cache. Because each block fetch overwrites older cache contents, a small number of blocks results in data being overwritten shortly after they are fetched. As a block becomes larger, each additional word is farther from the requested word and therefore less likely to be needed in the near future. The relationship between block size and hit ratio is complex, and no set approach is judged to be the best in all circumstances.   Pentium 4 and ARM cache organizations The processor core consists of four major components: Fetch/decode unit – fetches program instruction in order from the L2 cache, decodes these into a series of micro-operations, and stores the results in the L2 instruction cache Out-of-order execution logic – Schedules execution of the micro-operations subject to data dependencies and resource availability – thus micro-operations may be scheduled for execution in a different order than they were fetched from the instruction stream. As time permits, this unit schedules speculative execution of micro-operations that may be required in the future Execution units – These units execute micro-operations, fetching the required data from the L1 data cache and temporarily storing results in registers Memory subsystem – This unit includes the L2 and L3 caches and the system bus, which is used to access main memory when the L1 and L2 caches have a cache miss and to access the system I/O resources

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