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• Adding a Network Loopback Adapter to Windows 8

  - by Greg Low

  I have to say that I continue to be frustrated with finding out how to do things in Windows 8. Here's another one and it's recorded so it might help someone else. I've also documented what I tried so that if anyone from the product group ever reads this, they'll understand how I searched for it and might try to make it easier.I wanted to add a network loopback adapter, to have a fixed IP address to work with when using an "internal" network with Hyper-V. (The fact that I even need to do this is also painful. I don't know why Hyper-V can't make it easy to work with host system folders, etc. as easily as I can with VirtualPC, VirtualBox, etc. but that's a topic for another day).In the end, what I needed was a known IP address on the same network that my guest OS was using, via the internal network (which allows connectivity from the host OS to/from guest OS's).I started by looking in the network adapters areas but there is no "add" functionality there. Realising that this was likely to be another unexpected challenge, I resorted to searching for info on doing this. I found KB article 2777200 entitled "Installing the Microsoft Loopback Adapter in Windows 8 and Windows Server 2012". Aha, I thought that's what I'd need. It describes the symptom as "You are trying to install the Microsoft Loopback Adapter, but are unable to find it." and that certainly sounded like me. There's a certain irony in documenting that something's hard to find instead of making it easier to find. Anyway, you'd hope that in that article, they'd then provide a step by step example of how to do it, but what they supply is this: The Microsoft Loopback Adapter was renamed in Windows 8 and Windows Server 2012. The new name is "Microsoft KM-TEST Loopback Adapter". When using the Add Hardware Wizard to manually add a network adapter, choose Manufacturer "Microsoft" and choose network adapter "Microsoft KM-TEST Loopback Adapter".The trick with this of course is finding the "Add Hardware Wizard". In Control Panel -> Hardware and Sound, there are options to "Add a device" and for "Device Manager". I tried the "Add a device" wizard (seemed logical to me) but after that wizard tries it's best, it just tells you that there isn't any hardware that it thinks it needs to install. It offers a link for when you can't find what you're looking for, but that leads to a generic help page that tells you how to do things like turning on your printer.In Device Manager, I checked the options in the program menus, and nothing useful was present. I even tried right-clicking "Network adapters", hoping that would lead to an option to add one, also to no avail.So back to the search engine I went, to try to find out where the "Add Hardware Wizard" is. Turns out I was in the right place in Device Manager, but I needed to right-click the computer's name, and choose "Add Legacy Hardware". No doubt that hasn't changed location lately but it's a while since I needed to add one so I'd forgotten. Regardless, I'm left wondering why it couldn't be in the menu as well.Anyway, for a step by step list, you need to do the following:1. From Control Panel, select "Device Manager" under the "Devices and Printers" section of the "Hardware and Sound" tab.2. Right-click the name of the computer at the top of the tree, and choose "Add Legacy Hardware".3. In the "Welcome to the Add Hardware Wizard" window, click Next.4. In the "The wizard can help you install other hardware" window, choose "Install the hardware that I manually select from a list" option and click Next.5. In the "The wizard did not find any new hardware on your computer" window, click Next.6. In the "From the list below, select the type of hardware you are installing" window, select "Network Adapters" from the list, and click Next.7. In the "Select Network Adapter" window, from the Manufacturer list, choose Microsoft, then in the Network Adapter window, choose "Microsoft KM-TEST Loopback Adapter", then click Next.8. In the "The wizard is ready to install your hardware" window, click Next.9. In the "Completing the Add Hardware Wizard" window, click Finish.Then you need to continue to set the IP address, etc.10. Back in Control Panel, select the "Network and Internet" tab, click "View Network Status and Tasks".11. In the "View your basic network information and set up connections" window, click "Change adapter settings".12. Right-click the new adapter that has been added (find it in the list by checking the device name of "Microsoft KM-TEST Loopback Adapter"), and click Properties.   

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• Some mail details about Orange Mauritius

  Being an internet service provider is not easy after all for a lot of companies. Luckily, there are quite some good international operators in this world. For example Orange Mauritius aka Mauritius Telecom aka Wanadoo(?) aka MyT here in Mauritius. The local circumstances give them a quasi-monopol position on fixed lines for telephony and therefore cable-based DSL internet connectivity. So far, not bad but as usual... the details. Just for the records, I am only using the services of Orange for mobile but friends and customers are bound, eh stuck, with other services of Orange Mauritius. And usually, being the IT guy, they get in touch with me to complain about problems or to ask questions on either their ADSL / MyT connection, mail services or whatever. Most of those issues are user-related and easily to solve by tweaking the configuration of their computer a little bit but sometimes it's getting weird. Using Orange ADSL... somewhere else Now, let's imagine we are an Orange ADSL customer for ages and we are using their mail services with our very own mail address like "[email protected]". We configured our mail client like Thunderbird, Outlook Express, Outlook or Windows Mail as publicly described, and we are able to receive and send emails like a champion. No problems at all, the world is green. Did I mention that we have a laptop? Ok, let's take our movable piece of information technology and visit a friend here on the island. Not surprising, he is also customer of Orange, so we can read and answer emails. But Orange is not the online internet service provider and one day, we happen to hang out with someone that uses Emtel via WiMAX or UMTS.. And the fun starts... We can still receive and read emails from our Orange mail account and the IT world is still bright but try to send mails to someone outside the domain "@intnet.mu" or "@orange.mu". Your mail client will deny sending mail with SMTP message 5.1.0 "blah not allowed". First guess, there is problem with the mail client, maybe magically the configuration changed over-night. But no it is still working at home... So, there is for sure a problem with the guy's internet connection. At least, it is his fault not to have Orange internet services, so it can not work properly... The Orange Mail FAQ After some more frustation we finally checkout the Orange Mail FAQ to see whether this (obviously?) common problem has been described already. Sorry, but those FAQ entries are even more confusing as it is not really clear how to handle this scenario. Best of all is that most of the entries are still refering to use servers of the domain "intnet.mu". I mean Orange will disable those systems in favour of the domain "orange.mu" in the near future and does not amend their FAQs. Come on, guys! Ok, settings for POP3 are there. Hm, what about the secure version POP3S? No signs at all... Even changing your mail client to use password encryption with STARTTLS is not allowed at all. Use "bow.intnet.mu" for incoming mail... Ahhh, pretty obvious host name. I mean, at least something like pop.intnet.mu or pop3.intnet.mu would have been more accurate. Funny of all, the hostname "pop.orange.mu" is accessible to receive your mail account. Alright, checking SMTP options for authentication or other like POP-before-SMTP or whatever well-known and established mechanism to send emails are described. I guess that spotting a whale or shark in Mauritian waters would be easier. Trial and error on SMTP settings reveal that neither STARTTLS or any other connection / password encryption is available. Using SSL/TLS on SMTP only reveals that there is no service answering your request. Calling customer service So, we have to bite into the bitter apple and get in touch with Orange customer service and complain/explain them our case and ask for advice. After some hiccups, we finally manage to get hold of someone competent in mail services and we receive the golden spoon of mail configuration made by Orange Mauritius: SMTP hostname: smtpauth.intnet.mu And the world of IT is surprisingly green again. Customer satisfaction? Dear Orange Mauritius, what's the problem with this information? Are you scared of mail spammer? Why isn't there any case in your FAQs? Ok, talking about your FAQs - simply said: they are badly outdated! Configure your mail client to use server name based in the domain intnet.mu but specify your account username with orange.mu as domain part. Although, that there are servers available on the domain orange.mu after all. So, why don't you provide current information like this: POP3 server name: pop.orange.muSMTP server name: smtp.orange.muSMTP authenticated: smtpauth.orange.mu It's not difficult, is it? In my humble opinion not really and you would provide clean, consistent and up-to-date information for your customers. This would produce less frustation and so less traffic on your customer service lines. Which after all, would improve the total user experience and satisfaction level on both sides. Without knowing these facts. Now, imagine you would take your laptop abroad and have to use other internet service providers to be able to be online... Calling your customer service would be unnecessary expensive!

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• How to Tell If Your Computer is Overheating and What to Do About It

  - by Chris Hoffman

  Heat is a computer’s enemy. Computers are designed with heat dispersion and ventilation in mind so they don’t overheat. If too much heat builds up, your computer may become unstable or suddenly shut down. The CPU and graphics card produce much more heat when running demanding applications. If there’s a problem with your computer’s cooling system, an excess of heat could even physically damage its components. Is Your Computer Overheating? When using a typical computer in a typical way, you shouldn’t have to worry about overheating at all. However, if you’re encountering system instability issues like abrupt shut downs, blue screens, and freezes — especially while doing something demanding like playing PC games or encoding video — your computer may be overheating. This can happen for several reasons. Your computer’s case may be full of dust, a fan may have failed, something may be blocking your computer’s vents, or you may have a compact laptop that was never designed to run at maximum performance for hours on end. Monitoring Your Computer’s Temperature First, bear in mind that different CPUs and GPUs (graphics cards) have different optimal temperature ranges. Before getting too worried about a temperature, be sure to check your computer’s documentation — or its CPU or graphics card specifications — and ensure you know the temperature ranges your hardware can handle. You can monitor your computer’s temperatures in a variety of different ways. First, you may have a way to monitor temperature that is already built into your system. You can often view temperature values in your computer’s BIOS or UEFI settings screen. This allows you to quickly see your computer’s temperature if Windows freezes or blue screens on you — just boot the computer, enter the BIOS or UEFI screen, and check the temperatures displayed there. Note that not all BIOSes or UEFI screens will display this information, but it is very common. There are also programs that will display your computer’s temperature. Such programs just read the sensors inside your computer and show you the temperature value they report, so there are a wide variety of tools you can use for this, from the simple Speccy system information utility to an advanced tool like SpeedFan. HWMonitor also offer this feature, displaying a wide variety of sensor information. Be sure to look at your CPU and graphics card temperatures. You can also find other temperatures, such as the temperature of your hard drive, but these components will generally only overheat if it becomes extremely hot in the computer’s case. They shouldn’t generate too much heat on their own. If you think your computer may be overheating, don’t just glance as these sensors once and ignore them. Do something demanding with your computer, such as running a CPU burn-in test with Prime 95, playing a PC game, or running a graphical benchmark. Monitor the computer’s temperature while you do this, even checking a few hours later — does any component overheat after you push it hard for a while? Preventing Your Computer From Overheating If your computer is overheating, here are some things you can do about it: Dust Out Your Computer’s Case: Dust accumulates in desktop PC cases and even laptops over time, clogging fans and blocking air flow. This dust can cause ventilation problems, trapping heat and preventing your PC from cooling itself properly. Be sure to clean your computer’s case occasionally to prevent dust build-up. Unfortunately, it’s often more difficult to dust out overheating laptops. Ensure Proper Ventilation: Put the computer in a location where it can properly ventilate itself. If it’s a desktop, don’t push the case up against a wall so that the computer’s vents become blocked or leave it near a radiator or heating vent. If it’s a laptop, be careful to not block its air vents, particularly when doing something demanding. For example, putting a laptop down on a mattress, allowing it to sink in, and leaving it there can lead to overheating — especially if the laptop is doing something demanding and generating heat it can’t get rid of. Check if Fans Are Running: If you’re not sure why your computer started overheating, open its case and check that all the fans are running. It’s possible that a CPU, graphics card, or case fan failed or became unplugged, reducing air flow. Tune Up Heat Sinks: If your CPU is overheating, its heat sink may not be seated correctly or its thermal paste may be old. You may need to remove the heat sink and re-apply new thermal paste before reseating the heat sink properly. This tip applies more to tweakers, overclockers, and people who build their own PCs, especially if they may have made a mistake when originally applying the thermal paste. This is often much more difficult when it comes to laptops, which generally aren’t designed to be user-serviceable. That can lead to trouble if the laptop becomes filled with dust and needs to be cleaned out, especially if the laptop was never designed to be opened by users at all. Consult our guide to diagnosing and fixing an overheating laptop for help with cooling down a hot laptop. Overheating is a definite danger when overclocking your CPU or graphics card. Overclocking will cause your components to run hotter, and the additional heat will cause problems unless you can properly cool your components. If you’ve overclocked your hardware and it has started to overheat — well, throttle back the overclock! Image Credit: Vinni Malek on Flickr     

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• Organization &amp; Architecture UNISA Studies &ndash; Chap 5

  - by MarkPearl

  Learning Outcomes Describe the operation of a memory cell Explain the difference between DRAM and SRAM Discuss the different types of ROM Explain the concepts of a hard failure and a soft error respectively Describe SDRAM organization Semiconductor Main Memory The two traditional forms of RAM used in computers are DRAM and SRAM DRAM (Dynamic RAM) Divided into two technologies… Dynamic Static Dynamic RAM is made with cells that store data as charge on capacitors. The presence or absence of charge in a capacitor is interpreted as a binary 1 or 0. Because capacitors have natural tendency to discharge, dynamic RAM requires periodic charge refreshing to maintain data storage. The term dynamic refers to the tendency of the stored charge to leak away, even with power continuously applied. Although the DRAM cell is used to store a single bit (0 or 1), it is essentially an analogue device. The capacitor can store any charge value within a range, a threshold value determines whether the charge is interpreted as a 1 or 0. SRAM (Static RAM) SRAM is a digital device that uses the same logic elements used in the processor. In SRAM, binary values are stored using traditional flip flop logic configurations. SRAM will hold its data as along as power is supplied to it. Unlike DRAM, no refresh is required to retain data. SRAM vs. DRAM DRAM is simpler and smaller than SRAM. Thus it is more dense and less expensive than SRAM. The cost of the refreshing circuitry for DRAM needs to be considered, but if the machine requires a large amount of memory, DRAM turns out to be cheaper than SRAM. SRAMS are somewhat faster than DRAM, thus SRAM is generally used for cache memory and DRAM is used for main memory. Types of ROM Read Only Memory (ROM) contains a permanent pattern of data that cannot be changed. ROM is non volatile meaning no power source is required to maintain the bit values in memory. While it is possible to read a ROM, it is not possible to write new data into it. An important application of ROM is microprogramming, other applications include library subroutines for frequently wanted functions, System programs, Function tables. A ROM is created like any other integrated circuit chip, with the data actually wired into the chip as part of the fabrication process. To reduce costs of fabrication, we have PROMS. PROMS are… Written only once Non-volatile Written after fabrication Another variation of ROM is the read-mostly memory, which is useful for applications in which read operations are far more frequent than write operations, but for which non volatile storage is required. There are three common forms of read-mostly memory, namely… EPROM EEPROM Flash memory Error Correction Semiconductor memory is subject to errors, which can be classed into two categories… Hard failure – Permanent physical defect so that the memory cell or cells cannot reliably store data Soft failure – Random error that alters the contents of one or more memory cells without damaging the memory (common cause includes power supply issues, etc.) Most modern main memory systems include logic for both detecting and correcting errors. Error detection works as follows… When data is to be read into memory, a calculation is performed on the data to produce a code Both the code and the data are stored When the previously stored word is read out, the code is used to detect and possibly correct errors The error checking provides one of 3 possible results… No errors are detected – the fetched data bits are sent out An error is detected, and it is possible to correct the error. The data bits plus error correction bits are fed into a corrector, which produces a corrected set of bits to be sent out An error is detected, but it is not possible to correct it. This condition is reported Hamming Code See wiki for detailed explanation. We will probably need to know how to do a hemming code – refer to the textbook (pg. 188 – 189) Advanced DRAM organization One of the most critical system bottlenecks when using high-performance processors is the interface to main memory. This interface is the most important pathway in the entire computer system. The basic building block of main memory remains the DRAM chip. In recent years a number of enhancements to the basic DRAM architecture have been explored, and some of these are now on the market including… SDRAM (Synchronous DRAM) DDR-DRAM RDRAM SDRAM (Synchronous DRAM) SDRAM exchanges data with the processor synchronized to an external clock signal and running at the full speed of the processor/memory bus without imposing wait states. SDRAM employs a burst mode to eliminate the address setup time and row and column line precharge time after the first access In burst mode a series of data bits can be clocked out rapidly after the first bit has been accessed SDRAM has a multiple bank internal architecture that improves opportunities for on chip parallelism SDRAM performs best when it is transferring large blocks of data serially There is now an enhanced version of SDRAM known as double data rate SDRAM or DDR-SDRAM that overcomes the once-per-cycle limitation of SDRAM

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• How to Achieve Real-Time Data Protection and Availabilty....For Real

  - by JoeMeeks

  There is a class of business and mission critical applications where downtime or data loss have substantial negative impact on revenue, customer service, reputation, cost, etc. Because the Oracle Database is used extensively to provide reliable performance and availability for this class of application, it also provides an integrated set of capabilities for real-time data protection and availability. Active Data Guard, depicted in the figure below, is the cornerstone for accomplishing these objectives because it provides the absolute best real-time data protection and availability for the Oracle Database. This is a bold statement, but it is supported by the facts. It isn’t so much that alternative solutions are bad, it’s just that their architectures prevent them from achieving the same levels of data protection, availability, simplicity, and asset utilization provided by Active Data Guard. Let’s explore further. Backups are the most popular method used to protect data and are an essential best practice for every database. Not surprisingly, Oracle Recovery Manager (RMAN) is one of the most commonly used features of the Oracle Database. But comparing Active Data Guard to backups is like comparing apples to motorcycles. Active Data Guard uses a hot (open read-only), synchronized copy of the production database to provide real-time data protection and HA. In contrast, a restore from backup takes time and often has many moving parts - people, processes, software and systems – that can create a level of uncertainty during an outage that critical applications can’t afford. This is why backups play a secondary role for your most critical databases by complementing real-time solutions that can provide both data protection and availability. Before Data Guard, enterprises used storage remote-mirroring for real-time data protection and availability. Remote-mirroring is a sophisticated storage technology promoted as a generic infrastructure solution that makes a simple promise – whatever is written to a primary volume will also be written to the mirrored volume at a remote site. Keeping this promise is also what causes data loss and downtime when the data written to primary volumes is corrupt – the same corruption is faithfully mirrored to the remote volume making both copies unusable. This happens because remote-mirroring is a generic process. It has no  intrinsic knowledge of Oracle data structures to enable advanced protection, nor can it perform independent Oracle validation BEFORE changes are applied to the remote copy. There is also nothing to prevent human error (e.g. a storage admin accidentally deleting critical files) from also impacting the remote mirrored copy. Remote-mirroring tricks users by creating a false impression that there are two separate copies of the Oracle Database. In truth; while remote-mirroring maintains two copies of the data on different volumes, both are part of a single closely coupled system. Not only will remote-mirroring propagate corruptions and administrative errors, but the changes applied to the mirrored volume are a result of the same Oracle code path that applied the change to the source volume. There is no isolation, either from a storage mirroring perspective or from an Oracle software perspective.  Bottom line, storage remote-mirroring lacks both the smarts and isolation level necessary to provide true data protection. Active Data Guard offers much more than storage remote-mirroring when your objective is protecting your enterprise from downtime and data loss. Like remote-mirroring, an Active Data Guard replica is an exact block for block copy of the primary. Unlike remote-mirroring, an Active Data Guard replica is NOT a tightly coupled copy of the source volumes - it is a completely independent Oracle Database. Active Data Guard’s inherent knowledge of Oracle data block and redo structures enables a separate Oracle Database using a different Oracle code path than the primary to use the full complement of Oracle data validation methods before changes are applied to the synchronized copy. These include: physical check sum, logical intra-block checking, lost write validation, and automatic block repair. The figure below illustrates the stark difference between the knowledge that remote-mirroring can discern from an Oracle data block and what Active Data Guard can discern. An Active Data Guard standby also provides a range of additional services enabled by the fact that it is a running Oracle Database - not just a mirrored copy of data files. An Active Data Guard standby database can be open read-only while it is synchronizing with the primary. This enables read-only workloads to be offloaded from the primary system and run on the active standby - boosting performance by utilizing all assets. An Active Data Guard standby can also be used to implement many types of system and database maintenance in rolling fashion. Maintenance and upgrades are first implemented on the standby while production runs unaffected at the primary. After the primary and standby are synchronized and all changes have been validated, the production workload is quickly switched to the standby. The only downtime is the time required for user connections to transfer from one system to the next. These capabilities further expand the expectations of availability offered by a data protection solution beyond what is possible to do using storage remote-mirroring. So don’t be fooled by appearances.  Storage remote-mirroring and Active Data Guard replication may look similar on the surface - but the devil is in the details. Only Active Data Guard has the smarts, the isolation, and the simplicity, to provide the best data protection and availability for the Oracle Database. Stay tuned for future blog posts that dive into the many differences between storage remote-mirroring and Active Data Guard along the dimensions of data protection, data availability, cost, asset utilization and return on investment. For additional information on Active Data Guard, see: Active Data Guard Technical White Paper Active Data Guard vs Storage Remote-Mirroring Active Data Guard Home Page on the Oracle Technology Network

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• Community Branching

  - by Dane Morgridge

  As some may have noticed, I have taken a liking to Ruby (and Rails in particular) quite a bit recently. This last weekend I spoke at the NYC Code Camp on a comparison of ASP.NET and Rails as well as an intro to Entity Framework talk.  I am speaking at RubyNation in April and have submitted to other ruby conferences around the area and I am also doing a Rails and MongoDB talk at the Philly Code Camp in April. Before you start to think this is my "I'm leaving .NET post", which it isn't so I need to clarify. I am not, nor do I intend to any time in the near future plan on abandoning .NET.  I am simply branching out into another community based on a development technology that I very much enjoy.  If you look at my twitter bio, you will see that I am into Entity Framework, Ruby on Rails, C++ and ASP.NET MVC, and not necessarily in that order.  I know you're probably thinking to your self that I am crazy, which is probably true on several levels (especially the C++ part). I was actually crazy enough at the NYC Code Camp to show up wearing a Linux t-shirt, presenting with my MacBook Pro on Entity Framework, ASP.NET MVC and Rails. (I did get pelted in the head with candy by Rachel Appel for it though) At all of the code camps I am submitting to this year, i will be submitting sessions on likely all four topics, and some sessions will be a combination of 2 or more.  For example, my "ASP.NET MVC: A Gateway To Rails?" talk touches ASP.NET MVC, Entity Framework Code First and Rails. Simply put (and I talk about this in my MVC & Rails talk) is that learning and using Rails has made me a better ASP.NET MVC developer. Just one example of this is helper methods.  When I started working with ASP.NET MVC, I didn't really want to use helpers and preferred to just use standard html tags, especially where links were concerned.  It was just me being stubborn and not really seeing all of the benefit of the helpers.  To my defense, coming from WebForms, I wanted to be as bare metal as possible and it seemed at first like a lot of the helpers were an unnecessary abstraction. I took my first look at Rails back in v1 and didn't spend very much time with it so I dismissed it and went on my merry ASP.NET WebForms way.  Then I picked up ASP.NET MVC and grasped the MVC pattern itself much better. After this, I took another look at Rails and everything made sense.  I decided then to learn Rails. (I think it is important for developers to learn new languages and platforms regularly so it was a natural progression for me) I wanted to learn it the right way, so when I dug into code, everyone used helpers everywhere for pretty much everything possible. I took some time to dig in and found out how helpful they were and subsequently realized how awesome they were in ASP.NET MVC also and started using them. In short, I love Rails (and Ruby in general).  I also love ASP.NET MVC and Entity Framework and yes I still love C++.  I have varying degrees of love for them individually at any given moment and it is likely to shift based on the current project I am working on.  I know you're thinking it so before you ask the question. "Which do I use when?", I'm going to give the standard developer answer of: It depends.  There are a lot of factors that I am not going to even go into that would go into a decision.  The most basic question I would ask though is,  does this project depend on .NET?  If it does, then I'd say that ASP.NET MVC is probably going to be the more logical choice and I am going to leave it at that.  I am working on projects right now in both technologies and I don't see that changing anytime soon (one project even uses both). With all that being said, you'll find me at code camps, conferences and user groups presenting on .NET, Ruby or both, writing about .NET and Ruby and I will likely be blogging on both in the future.  I know of others that have successfully branched out to other communities and with any luck I'll be successful at it too. On a (sorta) side note, I read a post by Justin Etheredge the other day that pretty much sums up my feelings about Ruby as a language.  I highly recommend checking it out: What Is So Great About Ruby?

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• Displaying text letter by letter

  - by Evi

  I am planing to Write a Text adventure and I don't know how to make the text draw letter by letter in any other way than changing the variable from h to he to hel to hell to hello That would be a terrible amount of work since there are tons of dialogue. Here is the source code so far { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; Texture2D sampleBG; Texture2D TextBG; SpriteFont defaultfont; KeyboardState keyboardstate; public bool spacepress = false; public bool mspress = false; public int textheight = 425; public int rowspace = 40; public string namebox = "(null)"; public string Row1 = "(null)"; public string Row2 = "(null)"; public string Row3 = "(null)"; public string Row4 = "(null)"; public int Dialogue = 0; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; graphics.PreferredBackBufferHeight = 600; graphics.PreferredBackBufferWidth = 800; IsMouseVisible = true; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); // TODO: use this.Content to load your game content here sampleBG = Content.Load <Texture2D>("SampleBG"); defaultfont = Content.Load<SpriteFont>("SpriteFont1"); TextBG = Content.Load<Texture2D>("textbg"); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState keyboardstate = Keyboard.GetState(); MouseState mousestate = Mouse.GetState(); // Changes Dialgue by pressing Left Mouse Button or Space #region Dialogue changer if (mousestate.LeftButton == ButtonState.Pressed && mspress == false) { mspress = true; Dialogue = Dialogue + 1; } if (mousestate.LeftButton == ButtonState.Released && mspress == true) { mspress = false; } if (keyboardstate.IsKeyDown(Keys.Space) && spacepress == false) { spacepress = true; Dialogue = Dialogue + 1; } if (keyboardstate.IsKeyUp(Keys.Space) && spacepress == true) { spacepress = false; } #endregion // ------------------------------------------------------ // Dialgue Content #region Dialgue if (Dialogue == 1) { Row1 = "Input Text 1 Here."; Row2 = "Input Text 2 Here."; Row3 = "Input Text 3 Here."; Row4 = "Input Text 4 Here."; } if (Dialogue == 2) { Row1 = "Text 1"; Row2 = "Text 2"; Row3 = "Text 3"; Row4 = "Text 4"; } #endregion // ------------------------------------------------------ base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); // TODO: Add your drawing code here spriteBatch.Begin(); spriteBatch.Draw(sampleBG, new Rectangle(0, 0, 800, 600), Color.White); spriteBatch.Draw(TextBG, new Rectangle(0, 400, 800, 200), Color.White); spriteBatch.DrawString(defaultfont, Row1, new Vector2(10, (textheight + (rowspace * 0))), Color.Black); spriteBatch.DrawString(defaultfont, Row2, new Vector2(10, (textheight + (rowspace * 1))), Color.Black); spriteBatch.DrawString(defaultfont, Row3, new Vector2(10, (textheight + (rowspace * 2))), Color.Black); spriteBatch.DrawString(defaultfont, Row4, new Vector2(10, (textheight + (rowspace * 3))), Color.Black); spriteBatch.End(); base.Draw(gameTime); } } }

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• 2D Platformer Collision Handling

  - by defender-zone

  Hello, everyone! I am trying to create a 2D platformer (Mario-type) game and I am some having some issues with handling collisions properly. I am writing this game in C++, using SDL for input, image loading, font loading, etcetera. I am also using OpenGL via the FreeGLUT library in conjunction with SDL to display graphics. My method of collision detection is AABB (Axis-Aligned Bounding Box), which is really all I need to start with. What I need is an easy way to both detect which side the collision occurred on and handle the collisions properly. So, basically, if the player collides with the top of the platform, reposition him to the top; if there is a collision to the sides, reposition the player back to the side of the object; if there is a collision to the bottom, reposition the player under the platform. I have tried many different ways of doing this, such as trying to find the penetration depth and repositioning the player backwards by the penetration depth. Sadly, nothing I've tried seems to work correctly. Player movement ends up being very glitchy and repositions the player when I don't want it to. Part of the reason is probably because I feel like this is something so simple but I'm over-thinking it. If anyone thinks they can help, please take a look at the code below and help me try to improve on this if you can. I would like to refrain from using a library to handle this (as I want to learn on my own) or the something like the SAT (Separating Axis Theorem) if at all possible. Thank you in advance for your help! void world1Level1CollisionDetection() { for(int i; i < blocks; i++) { if (de2dCheckCollision(ball,block[i],0.0f,0.0f)==true) { int up = 0; int left = 0; int right = 0; int down = 0; if(ball.coords[0] < block[i].coords[0] && block[i].coords[0] < ball.coords[2] && ball.coords[2] < block[i].coords[2]) { left = 1; } if(block[i].coords[0] < ball.coords[0] && ball.coords[0] < block[i].coords[2] && block[i].coords[2] < ball.coords[2]) { right = 1; } if(ball.coords[1] < block[i].coords[1] && block[i].coords[1] < ball.coords[3] && ball.coords[3] < block[i].coords[3]) { up = 1; } if(block[i].coords[1] < ball.coords[1] && ball.coords[1] < block[i].coords[3] && block[i].coords[3] < ball.coords[3]) { down = 1; } cout << left << ", " << right << ", " << up << ", " << down << ", " << endl; if (left == 1) { ball.coords[0] = block[i].coords[0] - 16.0f; ball.coords[2] = block[i].coords[0] - 0.0f; } if (right == 1) { ball.coords[0] = block[i].coords[2] + 0.0f; ball.coords[2] = block[i].coords[2] + 16.0f; } if (down == 1) { ball.coords[1] = block[i].coords[3] + 0.0f; ball.coords[3] = block[i].coords[3] + 16.0f; } if (up == 1) { ball.yspeed = 0.0f; ball.gravity = 0.0f; ball.coords[1] = block[i].coords[1] - 16.0f; ball.coords[3] = block[i].coords[1] - 0.0f; } } if (de2dCheckCollision(ball,block[i],0.0f,0.0f)==false) { ball.gravity = -0.5f; } } } To explain what some of this code means: The blocks variable is basically an integer that is storing the amount of blocks, or platforms. I am checking all of the blocks using a for loop, and the number that the loop is currently on is represented by integer i. The coordinate system might seem a little weird, so that's worth explaining. coords[0] represents the x position (left) of the object (where it starts on the x axis). coords[1] represents the y position (top) of the object (where it starts on the y axis). coords[2] represents the width of the object plus coords[0] (right). coords[3] represents the height of the object plus coords[1] (bottom). de2dCheckCollision performs an AABB collision detection. Up is negative y and down is positive y, as it is in most games. Hopefully I have provided enough information for someone to help me successfully. If there is something I left out that might be crucial, let me know and I'll provide the necessary information. Finally, for anyone who can help, providing code would be very helpful and much appreciated. Thank you again for your help!

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• Unable to keep the connecting using a wireless bridge

  - by dan

  I am running Ubuntu 12.04 on a dell inspiron desktop (core 2 duo) and am using wicd to manage my network/wifi. I've found that the WiFi card in the machine has trouble staying connected to my router (I believe this is a function of distance between the two), so I've taken an old Belkin F5d7231 wireless router and installed dd-wrt on it to use as a wireless bridge hoping that it will have better reception. I think everything up through the wireless bridge is working OK since I have no problems accessing the internet through it with my MacBook. The problem arises when I try to hook the ubuntu machine up to the wireless bridge. It will connect for a few minutes, but it will quickly disconnect without clear triggering event; it may be more likely to disconnect if there is a heavy traffic load going over it (could be something as simple as "cat big_text_file" in an ssh session). I've tried switching from dhclient to dhcpcd without much improvement. Here is the output from the syslog when it connects: Jun 30 17:10:08 Chicabuntu dhcpcd[28278]: wlan1: dhcpcd not running Jun 30 17:10:08 Chicabuntu dhcpcd[28278]: wlan1: exiting Jun 30 17:10:08 Chicabuntu dhcpcd[28312]: eth0: dhcpcd not running Jun 30 17:10:08 Chicabuntu dhcpcd[28312]: eth0: exiting Jun 30 17:10:08 Chicabuntu avahi-daemon[1041]: Interface eth0.IPv6 no longer relevant for mDNS. Jun 30 17:10:08 Chicabuntu avahi-daemon[1041]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::21c:c4ff:fe31:1a83. Jun 30 17:10:08 Chicabuntu avahi-daemon[1041]: Withdrawing address record for fe80::21c:c4ff:fe31:1a83 on eth0. Jun 30 17:10:08 Chicabuntu kernel: [15184.976127] tg3 0000:3f:00.0: irq 44 for MSI/MSI-X Jun 30 17:10:08 Chicabuntu kernel: [15185.010805] ADDRCONF(NETDEV_UP): eth0: link is not ready Jun 30 17:10:08 Chicabuntu dhcpcd[28347]: eth0: dhcpcd not running Jun 30 17:10:08 Chicabuntu dhcpcd[28347]: eth0: exiting Jun 30 17:10:08 Chicabuntu kernel: [15185.180156] tg3 0000:3f:00.0: irq 44 for MSI/MSI-X Jun 30 17:10:08 Chicabuntu kernel: [15185.212785] ADDRCONF(NETDEV_UP): eth0: link is not ready Jun 30 17:10:10 Chicabuntu kernel: [15187.027445] tg3 0000:3f:00.0: eth0: Link is up at 100 Mbps, full duplex Jun 30 17:10:10 Chicabuntu kernel: [15187.027452] tg3 0000:3f:00.0: eth0: Flow control is on for TX and on for RX Jun 30 17:10:10 Chicabuntu kernel: [15187.028300] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready Jun 30 17:10:10 Chicabuntu dhcpcd[28353]: eth0: dhcpcd 3.2.3 starting Jun 30 17:10:10 Chicabuntu dhcpcd[28353]: eth0: hardware address = 00:1c:c4:31:1a:83 Jun 30 17:10:10 Chicabuntu dhcpcd[28353]: eth0: DUID = 00:01:00:01:17:81:85:79:00:1c:c4:31:1a:83 Jun 30 17:10:10 Chicabuntu dhcpcd[28353]: eth0: broadcasting for a lease Jun 30 17:10:11 Chicabuntu avahi-daemon[1041]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::21c:c4ff:fe31:1a83. Jun 30 17:10:11 Chicabuntu avahi-daemon[1041]: New relevant interface eth0.IPv6 for mDNS. Jun 30 17:10:11 Chicabuntu avahi-daemon[1041]: Registering new address record for fe80::21c:c4ff:fe31:1a83 on eth0.*. Jun 30 17:10:20 Chicabuntu kernel: [15197.568016] eth0: no IPv6 routers present Jun 30 17:10:29 Chicabuntu dhcpcd[28353]: eth0: offered 192.168.1.111 from 192.168.1.254 Jun 30 17:10:29 Chicabuntu dhcpcd[28353]: eth0: checking 192.168.1.111 is available on attached networks Jun 30 17:10:30 Chicabuntu dhcpcd[28353]: eth0: leased 192.168.1.111 for 86400 seconds Jun 30 17:10:30 Chicabuntu dhcpcd[28353]: eth0: adding IP address 192.168.1.111/24 Jun 30 17:10:30 Chicabuntu avahi-daemon[1041]: Joining mDNS multicast group on interface eth0.IPv4 with address 192.168.1.111. Jun 30 17:10:30 Chicabuntu dhcpcd[28353]: eth0: adding default route via 192.168.1.254 metric 0 Jun 30 17:10:30 Chicabuntu dhcpcd[28353]: eth0: exiting Jun 30 17:10:30 Chicabuntu avahi-daemon[1041]: New relevant interface eth0.IPv4 for mDNS. Jun 30 17:10:30 Chicabuntu avahi-daemon[1041]: Registering new address record for 192.168.1.111 on eth0.IPv4. Jun 30 17:10:30 Chicabuntu dhcpcd.sh: interface eth0 has been configured with new IP=192.168.1.111 Jun 30 17:10:39 Chicabuntu ntpdate[28439]: adjust time server 91.189.94.4 offset 0.001915 sec And here is the syslog from when it shuts down the connection without reason: Jun 30 17:12:15 Chicabuntu kernel: [15312.575455] tg3 0000:3f:00.0: eth0: Link is down Jun 30 17:12:16 Chicabuntu dhcpcd[28603]: eth0: sending signal 1 to pid 28361 Jun 30 17:12:16 Chicabuntu dhcpcd[28361]: eth0: received SIGHUP, releasing lease Jun 30 17:12:16 Chicabuntu dhcpcd[28603]: eth0: exiting Jun 30 17:12:16 Chicabuntu avahi-daemon[1041]: Withdrawing address record for 192.168.1.111 on eth0. Jun 30 17:12:16 Chicabuntu avahi-daemon[1041]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.1.111. Jun 30 17:12:16 Chicabuntu avahi-daemon[1041]: Interface eth0.IPv4 no longer relevant for mDNS. Jun 30 17:12:16 Chicabuntu dhcpcd[28361]: eth0: removing default route via 192.168.1.254 metric 0 Jun 30 17:12:16 Chicabuntu avahi-daemon[1041]: Interface eth0.IPv6 no longer relevant for mDNS. Jun 30 17:12:16 Chicabuntu avahi-daemon[1041]: Leaving mDNS multicast group on interface eth0.IPv6 with address fe80::21c:c4ff:fe31:1a83. Jun 30 17:12:16 Chicabuntu avahi-daemon[1041]: Withdrawing address record for fe80::21c:c4ff:fe31:1a83 on eth0. Jun 30 17:12:16 Chicabuntu dhcpcd[28361]: eth0: netlink: No such process Jun 30 17:12:16 Chicabuntu dhcpcd[28361]: eth0: removing IP address 192.168.1.111/24 Jun 30 17:12:16 Chicabuntu dhcpcd[28361]: eth0: netlink: Cannot assign requested address Jun 30 17:12:16 Chicabuntu dhcpcd[28361]: eth0: exiting Jun 30 17:12:16 Chicabuntu dhcpcd.sh: interface eth0 has been brought down Jun 30 17:12:17 Chicabuntu kernel: [15313.612141] tg3 0000:3f:00.0: irq 44 for MSI/MSI-X Jun 30 17:12:17 Chicabuntu kernel: [15313.644703] ADDRCONF(NETDEV_UP): eth0: link is not ready Jun 30 17:12:17 Chicabuntu dhcpcd[28674]: wlan1: dhcpcd not running Jun 30 17:12:17 Chicabuntu dhcpcd[28674]: wlan1: exiting Jun 30 17:12:17 Chicabuntu dhcpcd[28708]: eth0: dhcpcd not running Jun 30 17:12:17 Chicabuntu dhcpcd[28708]: eth0: exiting Jun 30 17:12:17 Chicabuntu kernel: [15313.912147] tg3 0000:3f:00.0: irq 44 for MSI/MSI-X Jun 30 17:12:17 Chicabuntu kernel: [15313.944746] ADDRCONF(NETDEV_UP): eth0: link is not ready Jun 30 17:12:18 Chicabuntu kernel: [15315.592569] tg3 0000:3f:00.0: eth0: Link is up at 100 Mbps, full duplex Jun 30 17:12:18 Chicabuntu kernel: [15315.592576] tg3 0000:3f:00.0: eth0: Flow control is on for TX and on for RX Jun 30 17:12:18 Chicabuntu kernel: [15315.593399] ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready Jun 30 17:12:20 Chicabuntu avahi-daemon[1041]: Joining mDNS multicast group on interface eth0.IPv6 with address fe80::21c:c4ff:fe31:1a83. Jun 30 17:12:20 Chicabuntu avahi-daemon[1041]: New relevant interface eth0.IPv6 for mDNS. Jun 30 17:12:20 Chicabuntu avahi-daemon[1041]: Registering new address record for fe80::21c:c4ff:fe31:1a83 on eth0.*. Jun 30 17:12:29 Chicabuntu kernel: [15325.680019] eth0: no IPv6 routers present If this isn't useful, I can also post the wicd log, but that is kind of long. If anyone could help me I would be eternally grateful.

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• Computer Networks UNISA - Chap 15 &ndash; Network Management

  - by MarkPearl

  After reading this section you should be able to Understand network management and the importance of documentation, baseline measurements, policies, and regulations to assess and maintain a network’s health. Manage a network’s performance using SNMP-based network management software, system and event logs, and traffic-shaping techniques Identify the reasons for and elements of an asset managements system Plan and follow regular hardware and software maintenance routines Fundamentals of Network Management Network management refers to the assessment, monitoring, and maintenance of all aspects of a network including checking for hardware faults, ensuring high QoS, maintaining records of network assets, etc. Scope of network management differs depending on the size and requirements of the network. All sub topics of network management share the goals of enhancing the efficiency and performance while preventing costly downtime or loss. Documentation The way documentation is stored may vary, but to adequately manage a network one should at least record the following… Physical topology (types of LAN and WAN topologies – ring, star, hybrid) Access method (does it use Ethernet 802.3, token ring, etc.) Protocols Devices (Switches, routers, etc) Operating Systems Applications Configurations (What version of operating system and config files for serve / client software) Baseline Measurements A baseline is a report of the network’s current state of operation. Baseline measurements might include the utilization rate for your network backbone, number of users logged on per day, etc. Baseline measurements allow you to compare future performance increases or decreases caused by network changes or events with past network performance. Obtaining baseline measurements is the only way to know for certain whether a pattern of usage has changed, or whether a network upgrade has made a difference. There are various tools available for measuring baseline performance on a network. Policies, Procedures, and Regulations Following rules helps limit chaos, confusion, and possibly downtime. The following policies and procedures and regulations make for sound network management. Media installations and management (includes designing physical layout of cable, etc.) Network addressing policies (includes choosing and applying a an addressing scheme) Resource sharing and naming conventions (includes rules for logon ID’s) Security related policies Troubleshooting procedures Backup and disaster recovery procedures In addition to internal policies, a network manager must consider external regulatory rules. Fault and Performance Management After documenting every aspect of your network and following policies and best practices, you are ready to asses you networks status on an on going basis. This process includes both performance management and fault management. Network Management Software To accomplish both fault and performance management, organizations often use enterprise-wide network management software. There various software packages that do this, each collect data from multiple networked devices at regular intervals, in a process called polling. Each managed device runs a network management agent. So as not to affect the performance of a device while collecting information, agents do not demand significant processing resources. The definition of a managed devices and their data are collected in a MIB (Management Information Base). Agents communicate information about managed devices via any of several application layer protocols. On modern networks most agents use SNMP which is part of the TCP/IP suite and typically runs over UDP on port 161. Because of the flexibility and sophisticated network management applications are a challenge to configure and fine-tune. One needs to be careful to only collect relevant information and not cause performance issues (i.e. pinging a device every 5 seconds can be a problem with thousands of devices). MRTG (Multi Router Traffic Grapher) is a simple command line utility that uses SNMP to poll devices and collects data in a log file. MRTG can be used with Windows, UNIX and Linux. System and Event Logs Virtually every condition recognized by an operating system can be recorded. This is typically done using event logs. In Windows there is a GUI event log viewer. Similar information is recorded in UNIX and Linux in a system log. Much of the information collected in event logs and syslog files does not point to a problem, even if it is marked with a warning so it is important to filter your logs appropriately to reduce the noise. Traffic Shaping When a network must handle high volumes of network traffic, users benefit from performance management technique called traffic shaping. Traffic shaping involves manipulating certain characteristics of packets, data streams, or connections to manage the type and amount of traffic traversing a network or interface at any moment. Its goals are to assure timely delivery of the most important traffic while offering the best possible performance for all users. Several types of traffic prioritization exist including prioritizing traffic according to any of the following characteristics… Protocol IP address User group DiffServr VLAN tag in a Data Link layer frame Service or application Caching In addition to traffic shaping, a network or host might use caching to improve performance. Caching is the local storage of frequently needed files that would otherwise be obtained from an external source. By keeping files close to the requester, caching allows the user to access those files quickly. The most common type of caching is Web caching, in which Web pages are stored locally. To an ISP, caching is much more than just convenience. It prevents a significant volume of WAN traffic, thus improving performance and saving money. Asset Management Another key component in managing networks is identifying and tracking its hardware. This is called asset management. The first step to asset management is to take an inventory of each node on the network. You will also want to keep records of every piece of software purchased by your organization. Asset management simplifies maintaining and upgrading the network chiefly because you know what the system includes. In addition, asset management provides network administrators with information about the costs and benefits of certain types of hardware or software. Change Management Networks are always in a stage of flux with various aspects including… Software changes and patches Client Upgrades Shared Application Upgrades NOS Upgrades Hardware and Physical Plant Changes Cabling Upgrades Backbone Upgrades For a detailed explanation on each of these read the textbook (Page 750 – 761)

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• Best way to store a large amount of game objects and update the ones onscreen

  - by user3002473

  Good afternoon guys! I'm a young beginner game developer working on my first large scale game project and I've run into a situation where I'm not quite sure what the best solution may be (if there is a lone solution). The question may be vague (if anyone can think of a better title after having read the question, please edit it) or broad but I'm not quite sure what to do and I thought it would help just to discuss the problem with people more educated in the field. Before we get started, here are some of the questions I've looked at for help in the past: Best way to keep track of game objects Elegant way to simulate large amounts of entities within a game world What is the most efficient container to store dynamic game objects in? I've also read articles about different data structures commonly used in games to store game objects such as this one about slot maps, but none of them are really what I'm looking for. Also, if it helps at all I'm using Python 3 to design the game. It has to be Python 3, if I could I would use C++ or Unityscript or something else, but I'm restricted to having to use Python 3. My game will be a form of side scroller shooter game. In said game the player will traverse large rooms with large amounts of enemies and other game objects to update (think some of the larger areas in Cave Story or Iji). The player obviously can't see the entire room all at once, so there is a viewport that follows the player around and renders only a selection of the room and the game objects that it contains. This is not a foreign concept. The part that's getting me confused has to do with how certain game objects are updated. Some of them are to be updated constantly, regardless of whether or not they can be seen. Other objects however are only to be updated when they are onscreen (for example, an enemy would only be updated to react to the player when it is onscreen or when it is in a certain range of the screen). Another problem is that game objects have to be easily referable by other game objects; something that happens in the player's update() method may affect another object in the world. Collision detection in games is always a serious problem. I need a way of containing the game objects such that it minimizes the number of cases when testing for collisions against one another. The final problem is that of creating and destroying game objects. I think this problem is pretty self explanatory. To store the game objects then I've considered a number of different methods. The original method I had was to simply store all the objects in a hash table by an id. This method was simple, and decently fast as it allows all the objects to be looked up in O(1) complexity, and also allows them to be deleted fairly easily. Hash collisions would not be a major problem; I wasn't originally planning on using computer generated ids to store the game objects I was going to rely on them all using ids given to them by the game designer (such names would be strings like 'Player' or 'EnemyWeapon4'), and even if I did use computer generated ids, if I used a decent hashing algorithm then the chances of collisions would be around 1 in 4 billion. The problem with using a hash table however is that it is inefficient in checking to see what objects are in range of the viewport. Considering the fact that certain game objects move (as well as the viewport itself), the only solution I could think of in order to only update objects that are in the viewport would be to iterate through every object in the hash table and check if it is in the viewport or not, updating only the ones that are in the valid area. This would be incredibly slow in scenarios where the amount of game objects exceeds 500, or even 200. The second solution was to store everything in a 2-d list. The world is partitioned up into cells (a tilemap essentially), where each cell or tile is the same size and is square. Each cell would contain a list of the game objects that are currently occupying it (each game object would be inserted into a cell depending on the center of the object's collision mask). A 2-d list would allow me to take the top-left and bottom-right corners of the viewport and easily grab a rectangular area of the grid containing only the cells containing entities that are in valid range to be updated. This method also solves the problem of collision detection; when I take an entity I can find the cell that it is currently in, then check only against entities in it's cell and the 8 cells around it. One problem with this system however is that it prohibits easy lookup of game objects. One solution I had would be to simultaneously keep a hash table that would contain all the positions of the objects in the 2-d list indexed by the id of said object. The major problem with a 2-d list is that it would need to be rebuilt every single game frame (along with the hash table of object positions), which may be a serious detriment to game speed. Both systems have ups and downs and seem to solve some of each other's problems, however using them both together doesn't seem like the best solution either. If anyone has any thoughts, ideas, suggestions, comments, opinions or solutions on new data structures or better implementations of the existing data structures I have in mind, please post, any and all criticism and help is welcome. Thanks in advance! EDIT: Please don't close the question because it has a bad title, I'm just bad with names!

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• Computer Networks UNISA - Chap 14 &ndash; Insuring Integrity &amp; Availability

  - by MarkPearl

  After reading this section you should be able to Identify the characteristics of a network that keep data safe from loss or damage Protect an enterprise-wide network from viruses Explain network and system level fault tolerance techniques Discuss issues related to network backup and recovery strategies Describe the components of a useful disaster recovery plan and the options for disaster contingencies What are integrity and availability? Integrity – the soundness of a networks programs, data, services, devices, and connections Availability – How consistently and reliably a file or system can be accessed by authorized personnel A number of phenomena can compromise both integrity and availability including… security breaches natural disasters malicious intruders power flaws human error users etc Although you cannot predict every type of vulnerability, you can take measures to guard against the most damaging events. The following are some guidelines… Allow only network administrators to create or modify NOS and application system users. Monitor the network for unauthorized access or changes Record authorized system changes in a change management system’ Install redundant components Perform regular health checks on the network Check system performance, error logs, and the system log book regularly Keep backups Implement and enforce security and disaster recovery policies These are just some of the basics… Malware Malware refers to any program or piece of code designed to intrude upon or harm a system or its resources. Types of Malware… Boot sector viruses Macro viruses File infector viruses Worms Trojan Horse Network Viruses Bots Malware characteristics Some common characteristics of Malware include… Encryption Stealth Polymorphism Time dependence Malware Protection There are various tools available to protect you from malware called anti-malware software. These monitor your system for indications that a program is performing potential malware operations. A number of techniques are used to detect malware including… Signature Scanning Integrity Checking Monitoring unexpected file changes or virus like behaviours It is important to decide where anti-malware tools will be installed and find a balance between performance and protection. There are several general purpose malware policies that can be implemented to protect your network including… Every compute in an organization should be equipped with malware detection and cleaning software that regularly runs Users should not be allowed to alter or disable the anti-malware software Users should know what to do in case the anti-malware program detects a malware virus Users should be prohibited from installing any unauthorized software on their systems System wide alerts should be issued to network users notifying them if a serious malware virus has been detected. Fault Tolerance Besides guarding against malware, another key factor in maintaining the availability and integrity of data is fault tolerance. Fault tolerance is the ability for a system to continue performing despite an unexpected hardware or software malfunction. Fault tolerance can be realized in varying degrees, the optimal level of fault tolerance for a system depends on how critical its services and files are to productivity. Generally the more fault tolerant the system, the more expensive it is. The following describe some of the areas that need to be considered for fault tolerance. Environment (Temperature and humidity) Power Topology and Connectivity Servers Storage Power Typical power flaws include Surges – a brief increase in voltage due to lightening strikes, solar flares or some idiot at City Power Noise – Fluctuation in voltage levels caused by other devices on the network or electromagnetic interference Brownout – A sag in voltage for just a moment Blackout – A complete power loss The are various alternate power sources to consider including UPS’s and Generators. UPS’s are found in two categories… Standby UPS – provides continuous power when mains goes down (brief period of switching over) Online UPS – is online all the time and the device receives power from the UPS all the time (the UPS is charged continuously) Servers There are various techniques for fault tolerance with servers. Server mirroring is an option where one device or component duplicates the activities of another. It is generally an expensive process. Clustering is a fault tolerance technique that links multiple servers together to appear as a single server. They share processing and storage responsibilities and if one unit in the cluster goes down, another unit can be brought in to replace it. Storage There are various techniques available including the following… RAID Arrays NAS (Storage (Network Attached Storage) SANs (Storage Area Networks) Data Backup A backup is a copy of data or program files created for archiving or safekeeping. Many different options for backups exist with various media including… These vary in cost and speed. Optical Media Tape Backup External Disk Drives Network Backups Backup Strategy After selecting the appropriate tool for performing your servers backup, devise a backup strategy to guide you through performing reliable backups that provide maximum data protection. Questions that should be answered include… What data must be backed up At what time of day or night will the backups occur How will you verify the accuracy of the backups Where and for how long will backup media be stored Who will take responsibility for ensuring that backups occurred How long will you save backups Where will backup and recovery documentation be stored Different backup methods provide varying levels of certainty and corresponding labour cost. There are also different ways to determine which files should be backed up including… Full backup – all data on all servers is copied to storage media Incremental backup – Only data that has changed since the last full or incremental backup is copied to a storage medium Differential backup – Only data that has changed since the last backup is coped to a storage medium Disaster Recovery Disaster recovery is the process of restoring your critical functionality and data after an enterprise wide outage has occurred. A disaster recovery plan is for extreme scenarios (i.e. fire, line fault, etc). A cold site is a place were the computers, devices, and connectivity necessary to rebuild a network exist but they are not appropriately configured. A warm site is a place where the computers, devices, and connectivity necessary to rebuild a network exists with some appropriately configured devices. A hot site is a place where the computers, devices, and connectivity necessary to rebuild a network exists and all are appropriately configured.

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• Which of these algorithms is best for my goal?

  - by JonathonG

  I have created a program that restricts the mouse to a certain region based on a black/white bitmap. The program is 100% functional as-is, but uses an inaccurate, albeit fast, algorithm for repositioning the mouse when it strays outside the area. Currently, when the mouse moves outside the area, basically what happens is this: A line is drawn between a pre-defined static point inside the region and the mouse's new position. The point where that line intersects the edge of the allowed area is found. The mouse is moved to that point. This works, but only works perfectly for a perfect circle with the pre-defined point set in the exact center. Unfortunately, this will never be the case. The application will be used with a variety of rectangles and irregular, amorphous shapes. On such shapes, the point where the line drawn intersects the edge will usually not be the closest point on the shape to the mouse. I need to create a new algorithm that finds the closest point to the mouse's new position on the edge of the allowed area. I have several ideas about this, but I am not sure of their validity, in that they may have far too much overhead. While I am not asking for code, it might help to know that I am using Objective C / Cocoa, developing for OS X, as I feel the language being used might affect the efficiency of potential methods. My ideas are: Using a bit of trigonometry to project lines would work, but that would require some kind of intense algorithm to test every point on every line until it found the edge of the region... That seems too resource intensive since there could be something like 200 lines that would have each have to have as many as 200 pixels checked for black/white.... Using something like an A* pathing algorithm to find the shortest path to a black pixel; however, A* seems resource intensive, even though I could probably restrict it to only checking roughly in one direction. It also seems like it will take more time and effort than I have available to spend on this small portion of the much larger project I am working on, correct me if I am wrong and it would not be a significant amount of code (100 lines or around there). Mapping the border of the region before the application begins running the event tap loop. I think I could accomplish this by using my current line-based algorithm to find an edge point and then initiating an algorithm that checks all 8 pixels around that pixel, finds the next border pixel in one direction, and continues to do this until it comes back to the starting pixel. I could then store that data in an array to be used for the entire duration of the program, and have the mouse re-positioning method check the array for the closest pixel on the border to the mouse target position. That last method would presumably execute it's initial border mapping fairly quickly. (It would only have to map between 2,000 and 8,000 pixels, which means 8,000 to 64,000 checked, and I could even permanently store the data to make launching faster.) However, I am uncertain as to how much overhead it would take to scan through that array for the shortest distance for every single mouse move event... I suppose there could be a shortcut to restrict the number of elements in the array that will be checked to a variable number starting with the intersecting point on the line (from my original algorithm), and raise/lower that number to experiment with the overhead/accuracy tradeoff. Please let me know if I am over thinking this and there is an easier way that will work just fine, or which of these methods would be able to execute something like 30 times per second to keep mouse movement smooth, or if you have a better/faster method. I've posted relevant parts of my code below for reference, and included an example of what the area might look like. (I check for color value against a loaded bitmap that is black/white.) // // This part of my code runs every single time the mouse moves. // CGPoint point = CGEventGetLocation(event); float tX = point.x; float tY = point.y; if( is_in_area(tX,tY, mouse_mask)){ // target is inside O.K. area, do nothing }else{ CGPoint target; //point inside restricted region: float iX = 600; // inside x float iY = 500; // inside y // delta to midpoint between iX,iY and tX,tY float dX; float dY; float accuracy = .5; //accuracy to loop until reached do { dX = (tX-iX)/2; dY = (tY-iY)/2; if(is_in_area((tX-dX),(tY-dY),mouse_mask)){ iX += dX; iY += dY; } else { tX -= dX; tY -= dY; } } while (abs(dX)>accuracy || abs(dY)>accuracy); target = CGPointMake(roundf(tX), roundf(tY)); CGDisplayMoveCursorToPoint(CGMainDisplayID(),target); } Here is "is_in_area(int x, int y)" : bool is_in_area(NSInteger x, NSInteger y, NSBitmapImageRep *mouse_mask){ NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSUInteger pixel[4]; [mouse_mask getPixel:pixel atX:x y:y]; if(pixel[0]!= 0){ [pool release]; return false; } [pool release]; return true; }

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• How to draw textures on a model

  - by marc wellman

  The following code is a complete XNA 3.1 program almost unaltered to that code skeleton Visual Studio is creating when creating a new project. The only things I have changed are imported a .x model to the content folder of the VS solution. (the model is a simple square with a texture spanning over it - made in Google Sketchup and exported with several .x exporters) in the Load() method I am loading the .x model into the game. The Draw() method uses a BasicEffect to render the model. Except these three things I haven't added any code. Why does the model does not show the texture ? What can I do to make the texture visible ? This is the texture file (a standard SketchUp texture from the palette): And this is what my program looks like - as you can see: No texture! Find below the complete source code of the program AND the complete .x file: namespace WindowsGame1 { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } Model newModel; /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); // TODO: usse this.Content to load your game content here newModel = Content.Load<Model>(@"aau3d"); foreach (ModelMesh mesh in newModel.Meshes) { foreach (ModelMeshPart meshPart in mesh.MeshParts) { meshPart.Effect = new BasicEffect(this.GraphicsDevice, null); } } } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { // TODO: Unload any non ContentManager content here } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { // Allows the game to exit if (GamePad.GetState(PlayerIndex.One).Buttons.Back == ButtonState.Pressed) this.Exit(); // TODO: Add your update logic here base.Update(gameTime); } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { if (newModel != null) { GraphicsDevice.Clear(Color.CornflowerBlue); Matrix[] transforms = new Matrix[newModel.Bones.Count]; newModel.CopyAbsoluteBoneTransformsTo(transforms); foreach (ModelMesh mesh in newModel.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.EnableDefaultLighting(); effect.TextureEnabled = true; effect.World = transforms[mesh.ParentBone.Index] * Matrix.CreateRotationY(0) * Matrix.CreateTranslation(new Vector3(0, 0, 0)); effect.View = Matrix.CreateLookAt(new Vector3(200, 1000, 200), Vector3.Zero, Vector3.Up); effect.Projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), 0.75f, 1.0f, 10000.0f); } mesh.Draw(); } } base.Draw(gameTime); } } } This is the model I am using (.x): xof 0303txt 0032 // SketchUp 6 -> DirectX (c)2008 edecadoudal, supports: faces, normals and textures Material Default_Material{ 1.0;1.0;1.0;1.0;; 3.2; 0.000000;0.000000;0.000000;; 0.000000;0.000000;0.000000;; } Material _Groundcover_RiverRock_4inch_{ 0.568627450980392;0.494117647058824;0.427450980392157;1.0;; 3.2; 0.000000;0.000000;0.000000;; 0.000000;0.000000;0.000000;; TextureFilename { "aau3d.xGroundcover_RiverRock_4inch.jpg"; } } Mesh mesh_0{ 4; -81.6535;0.0000;74.8031;, -0.0000;0.0000;0.0000;, -81.6535;0.0000;0.0000;, -0.0000;0.0000;74.8031;; 2; 3;0,1,2, 3;1,0,3;; MeshMaterialList { 2; 2; 1, 1; { Default_Material } { _Groundcover_RiverRock_4inch_ } } MeshTextureCoords { 4; -2.1168,-3.4022; 1.0000,-0.0000; 1.0000,-3.4022; -2.1168,-0.0000;; } MeshNormals { 4; 0.0000;1.0000;-0.0000; 0.0000;1.0000;-0.0000; 0.0000;1.0000;-0.0000; 0.0000;1.0000;-0.0000;; 2; 3;0,1,2; 3;1,0,3;; } }

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• Gamification at OOW

  - by erikanollwebb

  Last week was Oracle OpenWorld, and for those of you not in tech or downtown San Francisco, that might not mean a whole lot.  However, if you are familiar with it, Oracle OpenWorld is our premier customer event.  This year, more than 50,000 people attended.  It's not a good week to visit San Francisco on vacation because Oracle customers take over all the hotels in town!  It was crazy, but a lot of fun and it's a great opportunity for the Apps UX group to do customer research with a range of customers.  This year, more than 100+ customers and partners took the time to team up with our UX experts and provide feedback on new designs and ideas. Over three days,  UX teams conducted 8  one-on-one user feedback sessions, 4 focus groups and 7 surveys. In addition, we conducted a voice capture activity and were able to collect close to 70 speech samples at the lab and DEMOgrounds. This was a great opportunity for us to do some testing on some specific gamification concepts with a set of business analysts.  We pulled in 8 folks for a focus group on gamification concepts and whether they thought those would work for their teams. To get ready for this, my designer extraordinaire, Andrea Cantú, flew into town and we spent almost a week locked in a room together brainstorming design ideas.  We killed a few trees trying to get all of our concepts and other examples together in the process, but in the end, we put together a whole series of examples of how you might gamify an Oracle app (in this case, CRM).  Andrea is a genius for this kind of thing and the comps she created looked great.  Here's a picture of her hard at work!  We also had the good fortune to have my boss, Laurie Pattison and my usability contractor, Shobana Subramanian there to note take and observe as well.  Here's a few shots of us, hard at work preparing for the day (or checking out something on Laurie's iPhone...) To start things off, we gave an overview of gamification and I talked about what it's used for.  Then we gave the participants a scenario about our sales person and what we were trying to get her to do. It was a great opportunity to highlight what our business goals might be and why we might want to add game mechanics.  It was also a good way to get them thinking about how that might work for them in their environments and workplaces. There were some surprises for the day.  We asked how many of them were already familiar with the concept of gamification--only two people had heard of it and only one was using game mechanics in his work.  That's in contrast to a survey we just ran internally with folks in a dev org where almost 50% of about 450 respondents had heard of gamification.  As we discussed the ways game mechanics could be used, it became clear that many of the folks had seen some game mechanics in action but didn't know that's what they were.  We also noticed that the folks in this group felt that if they were trying to sell the concept in their orgs, they wouldn't call it gamification.  That's not a huge surprise to me--they said what we've heard in the past, that gamification does not seem like a serious term for enterprise software.  They said they'd sell it with the goals--as a means to increase behaviors by rewarding users for activities.  It's a funny problem.  The word puts some folks off, but at the same time, I haven't seen another one word description that quite captures the range of things that "gamification" can cover.  My guess is that the more mainstream the term becomes, the more desensitized we'll become to the idea the it's trivializing enterprise software in some way.  Still, it was interesting to note that this group still felt that they would not take this concept to their bosses or teams and call it "gamification".  They focused on the goals, and how we could incentivize desired behaviors with game mechanics.  As I have already stated in other posts, I feel like my org is more receptive to discussing how this is just a more transparent type of usability and user experience methods than talking about gamification.  That's the argument they said they would use. All in all, it was a good session.  I love getting to talk to customers, present ideas and concepts, and get their feedback and input.  It's the type of thing that really helps drive our designs and keeps us grounded in what our customers need/want.  We're already planning where to get more feedback opportunities in the coming months. 

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• What to do after a servicing fails on TFS 2010

  - by Martin Hinshelwood

  What do you do if you run a couple of hotfixes against your TFS 2010 server and you start to see seem odd behaviour? A customer of mine encountered that very problem, but they could not just, or at least not easily, go back a version.   You see, around the time of the TFS 2010 launch this company decided to upgrade their entire 250+ development team from TFS 2008 to TFS 2010. They encountered a few problems, owing mainly to the size of their TFS deployment, and the way they were using TFS. They were not doing anything wrong, but when you have the largest deployment of TFS outside of Microsoft you tend to run into problems that most people will never encounter. We are talking half a terabyte of source control in TFS with over 80 proxy servers. Its certainly the largest deployment I have ever heard of. When they did their upgrade way back in April, they found two major flaws in the product that meant that they had to back out of the upgrade and wait for a couple of hotfixes. KB983504 – Hotfix KB983578 – Patch KB2401992 -Hotfix In the time since they got the hotfixes they have run 6 successful trial migrations, but we are not talking minutes or hours here. When you have 400+ GB of data it takes time to copy it around. It takes time to do the upgrade and it takes time to do a backup. Well, last week it was crunch time with their developers off for Christmas they had a window of opportunity to complete the upgrade. Now these guys are good, but they wanted Northwest Cadence to be available “just in case”. They did not expect any problems as they already had 6 successful trial upgrades. The problems surfaced around 20 hours in after the first set of hotfixes had been applied. The new Team Project Collection, the only thing of importance, had disappeared from the Team Foundation Server Administration console. The collection would not reattach either. It would not even list the new collection as attachable! Figure: We know there is a database there, but it does not This was a dire situation as 20+ hours to repeat would leave the customer over time with 250+ developers sitting around doing nothing. We tried everything, and then we stumbled upon the command of last resort. TFSConfig Recover /ConfigurationDB:SQLServer\InstanceName;TFS_ConfigurationDBName /CollectionDB:SQLServer\instanceName;"Collection Name" -http://msdn.microsoft.com/en-us/library/ff407077.aspx WARNING: Never run this command! Now this command does something a little nasty. It assumes that there really should not be anything wrong and sets about fixing it. It ignores any servicing levels in the Team Project Collection database and forcibly applies the latest version of the schema. I am sure you can imagine the types of problems this may cause when the schema is updated leaving the data behind. That said, as far as we could see this collection looked good, and we were even able to find and attach the team project collection to the Configuration database. Figure: After attaching the TPC it enters a servicing mode After reattaching the team project collection we found the message “Re-Attaching”. Well, fair enough that sounds like something that may need to happen, and after checking that there was disk IO we left it to it. 14+ hours later, it was still not done so the customer raised a priority support call with MSFT and an engineer helped them out. Figure: Everything looks good, it is just offline. Tip: Did you know that these logs are not represented in the ~/Logs/* folder until they are opened once? The engineer dug around a bit and listened to our situation. He knew that we had run the dreaded “tfsconfig restore”, but was not phased. Figure: This message looks suspiciously like the wrong servicing version As it turns out, the servicing version was slightly out of sync with the schema. KB Schema Successful           KB983504 341 Yes   KB983578 344 sort of   KB2401992 360 nope   Figure: KB, Schema table with notation to its success The Schema version above represents the final end of run version for that hotfix or patch. The only way forward The problem was that the version was somewhere between 341 and 344. This is not a nice place to be in and the engineer give us the  only way forward as the removal of the servicing number from the database so that the re-attach process would apply the latest schema. if his sounds a little like the “tfsconfig recover” command then you are exactly right. Figure: Sneakily changing that 3 to a 1 should do the trick Figure: Changing the status and dropping the version should do it Now that we have done that we should be able to safely reattach and enable the Team Project Collection. Figure: The TPC is now all attached and running You may think that this is the end of the story, but it is not. After a while of mulling and seeking expert advice we came to the opinion that the database was, for want of a better term, “hosed”. There could well be orphaned data in there and the likelihood that we would have problems later down the line is pretty high. We contacted the customer back and made them aware that in all likelihood the repaired database was more like a “cut and shut” than anything else, and at the first sign of trouble later down the line was likely to split in two. So with 40+ hours invested in getting this new database ready the customer threw it away and started again. What would you do? Would you take the “cut and shut” to production and hope for the best?

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• Loading XML file containing leading zeros with SSIS preserving the zeros

  - by Compudicted

  Visiting the MSDN SQL Server Integration Services Forum oftentimes I could see that people would pop up asking this question: “why I am not able to load an element from an XML file that contains zeros so the leading/trailing zeros would remain intact?”. I started to suspect that such a trivial and often-required operation perhaps is being misunderstood by the developer community. I would also like to add that the whole state of affairs surrounding the XML today is probably also going to be increasingly affected by a motion of people who dislike XML in general and many aspects of it as XSD and XSLT invoke a negative reaction at best. Nevertheless, XML is in wide use today and its importance as a bridge between diverse systems is ever increasing. Therefore, I deiced to write up an example of loading an arbitrary XML file that contains leading zeros in one of its elements using SSIS so the leading zeros would be preserved keeping in mind the goal on simplicity into a table in SQL Server database. To start off bring up your BIDS (running as admin) and add a new Data Flow Task (DFT). This DFT will serve as container to adding our XML processing elements (besides, the XML Source is not available anywhere else other than from within the DFT). Double-click your DFT and drag and drop the XMS Source component from the Tool Box’s Data Flow Sources. Now, let the fun begin! Being inspired by the upcoming Christmas I created a simple XML file with one set of data that contains an imaginary SSN number of Rudolph containing several leading zeros like 0000003. This file can be viewed here. To configure the XML Source of course it is quite intuitive to point it to our XML file, next what the XML source needs is either an embedded schema (XSD) or it can generate one for us. In lack of the one I opted to auto-generate it for me and I ended up with an XSD that looked like: <?xml version="1.0"?> <xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:element name="XMasEvent"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="CaseInfo"> <xs:complexType> <xs:sequence> <xs:element minOccurs="0" name="ID" type="xs:unsignedByte" /> <xs:element minOccurs="0" name="CreatedDate" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="LastName" type="xs:string" /> <xs:element minOccurs="0" name="FirstName" type="xs:string" /> <xs:element minOccurs="0" name="SSN" type="xs:unsignedByte" /> <!-- Becomes string -- > <xs:element minOccurs="0" name="DOB" type="xs:unsignedInt" /> <xs:element minOccurs="0" name="Event" type="xs:string" /> <xs:element minOccurs="0" name="ClosedDate" /> </xs:sequence> </xs:complexType> </xs:element> </xs:sequence> </xs:complexType> </xs:element> </xs:schema> As an aside on the XML file: if your XML file does not contain the outer node (<XMasEvent>) then you may end up in a situation where you see just one field in the output. Now please note that the SSN element’s data type was chosen to be of unsignedByte (and this is for a reason). The reason is stemming from the fact all our figures in the element are digits, this is good, but this is not exactly what we need, because if we will attempt to load the data with this XSD then we are going to either get errors on the destination or most typically lose the leading zeros. So the next intuitive choice is to change the data type to string. Besides, if a SSIS package was already created based on this XSD and the data type change was done thereafter, one should re-set the metadata by right-clicking the XML Source and choosing “Advanced Editor” in which there is a refresh button at the bottom left which will do the trick. So far so good, we are ready to load our XML file, well actually yes, and no, in my experience typically some data conversion may be required. So depending on your data destination you may need to tweak the data types targeted. Let’s add a Data Conversion Task to our DFT. Your package should look like: To make the story short I only will cover the SSN field, so in my data source the target SQL Table has it as nchar(10) and we chose string in our XSD (yes, this is a big difference), under such circumstances the SSIS will complain. So will go and manipulate on the data type of SSN by making it Unicode String (DT_WSTR), World String per se. The conversion should look like: The peek at the Metadata: We are almost there, now all we need is to configure the destination. For simplicity I chose SQL Server Destination. The mapping is a breeze, F5 and I am able to insert my data into SQL Server now! Checking the zeros – they are all intact!

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• Computer Networks UNISA - Chap 8 &ndash; Wireless Networking

  - by MarkPearl

  After reading this section you should be able to Explain how nodes exchange wireless signals Identify potential obstacles to successful transmission and their repercussions, such as interference and reflection Understand WLAN architecture Specify the characteristics of popular WLAN transmission methods including 802.11 a/b/g/n Install and configure wireless access points and their clients Describe wireless MAN and WAN technologies, including 802.16 and satellite communications The Wireless Spectrum All wireless signals are carried through the air by electromagnetic waves. The wireless spectrum is a continuum of the electromagnetic waves used for data and voice communication. The wireless spectrum falls between 9KHZ and 300 GHZ. Characteristics of Wireless Transmission Antennas Each type of wireless service requires an antenna specifically designed for that service. The service’s specification determine the antenna’s power output, frequency, and radiation pattern. A directional antenna issues wireless signals along a single direction. An omnidirectional antenna issues and receives wireless signals with equal strength and clarity in all directions The geographical area that an antenna or wireless system can reach is known as its range Signal Propagation LOS (line of sight) uses the least amount of energy and results in the reception of the clearest possible signal. When there is an obstacle in the way, the signal may… pass through the object or be obsrobed by the object or may be subject to reflection, diffraction or scattering. Reflection – waves encounter an object and bounces off it. Diffraction – signal splits into secondary waves when it encounters an obstruction Scattering – is the diffusion or the reflection in multiple different directions of a signal Signal Degradation Fading occurs as a signal hits various objects. Because of fading, the strength of the signal that reaches the receiver is lower than the transmitted signal strength. The further a signal moves from its source, the weaker it gets (this is called attenuation) Signals are also affected by noise – the electromagnetic interference) Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wired signal. Frequency Ranges Older wireless devices used the 2.4 GHZ band to send and receive signals. This had 11 communication channels that are unlicensed. Newer wireless devices can also use the 5 GHZ band which has 24 unlicensed bands Narrowband, Broadband, and Spread Spectrum Signals Narrowband – a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies Broadband – uses a relatively wide band of the wireless spectrum and offers higher throughputs than narrowband technologies The use of multiple frequencies to transmit a signal is known as spread-spectrum technology. In other words a signal never stays continuously within one frequency range during its transmission. One specific implementation of spread spectrum is FHSS (frequency hoping spread spectrum). Another type is known as DSS (direct sequence spread spectrum) Fixed vs. Mobile Each type of wireless communication falls into one of two categories Fixed – the location of the transmitted and receiver do not move (results in energy saved because weaker signal strength is possible with directional antennas) Mobile – the location can change WLAN (Wireless LAN) Architecture There are two main types of arrangements Adhoc – data is sent directly between devices – good for small local devices Infrastructure mode – a wireless access point is placed centrally, that all devices connect with 802.11 WLANs The most popular wireless standards used on contemporary LANs are those developed by IEEE’s 802.11 committee. Over the years several distinct standards related to wireless networking have been released. Four of the best known standards are also referred to as Wi-Fi. They are…. 802.11b 802.11a 802.11g 802.11n These four standards share many characteristics. i.e. All 4 use half duplex signalling Follow the same access method Access Method 802.11 standards specify the use of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) to access a shared medium. Using CSMA/CA before a station begins to send data on an 802.11 network, it checks for existing wireless transmissions. If the source node detects no transmission activity on the network, it waits a brief period of time and then sends its transmission. If the source does detect activity, it waits a brief period of time before checking again. The destination node receives the transmission and, after verifying its accuracy, issues an acknowledgement (ACT) packet to the source. If the source receives the ACK it assumes the transmission was successful, – if it does not receive an ACK it assumes the transmission failed and sends it again. Association Two types of scanning… Active – station transmits a special frame, known as a prove, on all available channels within its frequency range. When an access point finds the probe frame, it issues a probe response. Passive – wireless station listens on all channels within its frequency range for a special signal, known as a beacon frame, issued from an access point – the beacon frame contains information necessary to connect to the point. Re-association occurs when a mobile user moves out of one access point’s range and into the range of another. Frames Read page 378 – 381 about frames and specific 802.11 protocols Bluetooth Networks Sony Ericson originally invented the Bluetooth technology in the early 1990s. In 1998 other manufacturers joined Ericsson in the Special Interest Group (SIG) whose aim was to refine and standardize the technology. Bluetooth was designed to be used on small networks composed of personal communications devices. It has become popular wireless technology for communicating among cellular telephones, phone headsets, etc. Wireless WANs and Internet Access Refer to pages 396 – 402 of the textbook for details.

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• Mixing Forms and Token Authentication in a single ASP.NET Application (the Details)

  - by Your DisplayName here!

  The scenario described in my last post works because of the design around HTTP modules in ASP.NET. Authentication related modules (like Forms authentication and WIF WS-Fed/Sessions) typically subscribe to three events in the pipeline – AuthenticateRequest/PostAuthenticateRequest for pre-processing and EndRequest for post-processing (like making redirects to a login page). In the pre-processing stage it is the modules’ job to determine the identity of the client based on incoming HTTP details (like a header, cookie, form post) and set HttpContext.User and Thread.CurrentPrincipal. The actual page (in the ExecuteHandler event) “sees” the identity that the last module has set. So in our case there are three modules in effect: FormsAuthenticationModule (AuthenticateRequest, EndRequest) WSFederationAuthenticationModule (AuthenticateRequest, PostAuthenticateRequest, EndRequest) SessionAuthenticationModule (AuthenticateRequest, PostAuthenticateRequest) So let’s have a look at the different scenario we have when mixing Forms auth and WS-Federation. Anoymous request to unprotected resource This is the easiest case. Since there is no WIF session cookie or a FormsAuth cookie, these modules do nothing. The WSFed module creates an anonymous ClaimsPrincipal and calls the registered ClaimsAuthenticationManager (if any) to transform it. The result (by default an anonymous ClaimsPrincipal) gets set. Anonymous request to FormsAuth protected resource This is the scenario where an anonymous user tries to access a FormsAuth protected resource for the first time. The principal is anonymous and before the page gets rendered, the Authorize attribute kicks in. The attribute determines that the user needs authentication and therefor sets a 401 status code and ends the request. Now execution jumps to the EndRequest event, where the FormsAuth module takes over. The module then converts the 401 to a redirect (302) to the forms login page. If authentication is successful, the login page sets the FormsAuth cookie.   FormsAuth authenticated request to a FormsAuth protected resource Now a FormsAuth cookie is present, which gets validated by the FormsAuth module. This cookie gets turned into a GenericPrincipal/FormsIdentity combination. The WS-Fed module turns the principal into a ClaimsPrincipal and calls the registered ClaimsAuthenticationManager. The outcome of that gets set on the context. Anonymous request to STS protected resource This time the anonymous user tries to access an STS protected resource (a controller decorated with the RequireTokenAuthentication attribute). The attribute determines that the user needs STS authentication by checking the authentication type on the current principal. If this is not Federation, the redirect to the STS will be made. After successful authentication at the STS, the STS posts the token back to the application (using WS-Federation syntax). Postback from STS authentication After the postback, the WS-Fed module finds the token response and validates the contained token. If successful, the token gets transformed by the ClaimsAuthenticationManager, and the outcome is a) stored in a session cookie, and b) set on the context. STS authenticated request to an STS protected resource This time the WIF Session authentication module kicks in because it can find the previously issued session cookie. The module re-hydrates the ClaimsPrincipal from the cookie and sets it.     FormsAuth and STS authenticated request to a protected resource This is kind of an odd case – e.g. the user first authenticated using Forms and after that using the STS. This time the FormsAuth module does its work, and then afterwards the session module stomps over the context with the session principal. In other words, the STS identity wins.   What about roles? A common way to set roles in ASP.NET is to use the role manager feature. There is a corresponding HTTP module for that (RoleManagerModule) that handles PostAuthenticateRequest. Does this collide with the above combinations? No it doesn’t! When the WS-Fed module turns existing principals into a ClaimsPrincipal (like it did with the FormsIdentity), it also checks for RolePrincipal (which is the principal type created by role manager), and turns the roles in role claims. Nice! But as you can see in the last scenario above, this might result in unnecessary work, so I would rather recommend consolidating all role work (and other claims transformations) into the ClaimsAuthenticationManager. In there you can check for the authentication type of the incoming principal and act accordingly. HTH

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• Using Resources the Right Way

  - by BuckWoody

  It’s an interesting time in computing technology. At one point there was a dearth of information available for solving a given problem, or educating ourselves on broader topics so that we can solve problems in the future. With dozens, perhaps hundreds or thousands of web sites and content available (for free, in many cases) from vendors, peers, even colleges and universities, it seems like there is actually too much information. Who has the time to absorb all this information and training? Even if you had the inclination, where to start? In fact, it seems so overwhelming that I often hear people saying that they can’t find the training they need, or that vendor X or Y “doesn’t help their users”. On questioning these folks, however, I often find that they – and sometimes I - haven’t put in the effort to learn what resources we have. That’s where blogs, like this one, can help. If you follow a blog, either by checking it often or perhaps subscribing to the Really Simple Syndication (RSS) feed, you’ll be able to spread out the search or create a mental filter for the information you need. But it’s not enough just read a blog or a web page. The creators need real feedback – what doesn’t work, and what does. Yes, you’re allowed to tell a vendor or writer “This helped me because…” so that you reinforce the positives. To be sure, bring up what doesn’t work as well –  that’s fine. But be specific, and be constructive. You’d be surprised at how much it matters. I know for a fact at Microsoft we listen – there is a real live person that reads your comments. I’m sure this is true of other vendors, and I also know that most blog authors – yours truly most especially – wants to know what you think.   In this blog entry I’d to call your attention to three resources you have at your disposal, and how you can use them to help. I’ll try to bring up things like this from time to time that I find useful, and cover in them in more depth like this. Think of this as a synopsis of a longer set of resources that you can use to filter whether you want to research further, bookmark, or forward on to a circle of friends where you think it might help them.   Data Driven Design Concepts http://msdn.microsoft.com/en-us/library/windowsazure/jj156154 I’ll start with a great site that walks you through the process of designing a solution from a data-first perspective. As you know, I believe all computing is merely re-arranging data. If you follow that logic as well, you’ll realize that whenever you create a solution, you should start at the data-end of the application. This resource helps you do that. Even if you don’t use the specific technologies the instructions use, the concepts hold for almost any other technology that deals with data. This should be a definite bookmark for a developer, DBA, or Data Architect. When I mentioned my admiration for this resource here at Microsoft, the team that created it contacted me and asked if I’d share an e-mail address to my readers so that you can comment on it. You’re guaranteed to be heard – you can suggest changes, talk about how useful – or not – it is, and so on. Here’s that address:  [email protected]   End-to-End Example of a complete Hybrid Application – with Live Demo https://azurestocktrader.cloudapp.net/Default.aspx I learn by example. I also like having ready-made, live, functional demos that show the completed solution at work. If you’ve ever wanted to learn how a complex, complete, hybrid application that bridges on-premises systems with cloud-based databases, code, functions and more, this is it. It’s a stock-trading simulator, and you can get everything from the design to the code itself, or you can just play with the application. It’s running on Windows Azure, the actual production servers we use for everything else. Using a Cloud-Based Service https://azureconfigweb.cloudapp.net/Default.aspx Along with that stock-trading application, you have a full demonstration and usable code sample of a web-based service available. If you’re a developer, this is a style of code you need to understand for everything from iPhone development to a full Service-Oriented Architecture (SOA) environment. So check out these resources. I’ll post more from time to time as I run across them. Hopefully they’ll be as useful to you as they are to me. Oh, and if you have a comment on any of the resources, let them know. And if you have any comments about these or any of my entries, feel free to post away. To quote a famous TV Show: “Hello Seattle – I’m listening…”

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• Data Source Security Part 5

  - by Steve Felts

  If you read through the first four parts of this series on data source security, you should be an expert on this focus area.  There is one more small topic to cover related to WebLogic Resource permissions.  After that comes the test, I mean example, to see with a real set of configuration parameters what the results are with some concrete values. WebLogic Resource Permissions All of the discussion so far has been about database credentials that are (eventually) used on the database side.  WLS has resource credentials to control what WLS users are allowed to access JDBC resources.  These can be defined on the Policies tab on the Security tab associated with the data source.  There are four permissions: “reserve” (get a new connection), “admin”, “shrink”, and reset (plus the all-inclusive “ALL”); we will focus on “reserve” here because we are talking about getting connections.  By default, JDBC resource permissions are completely open – anyone can do anything.  As soon as you add one policy for a permission, then all other users are restricted.  For example, if I add a policy so that “weblogic” can reserve a connection, then all other users will fail to reserve connections unless they are also explicitly added.  The validation is done for WLS user credentials only, not database user credentials.  Configuration of resources in general is described at “Create policies for resource instances” http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/security/CreatePoliciesForResourceInstances.html.  This feature can be very useful to restrict what code and users can get to your database. There are the three use cases: API Use database credentials User for permission checking getConnection() True or false Current WLS user getConnection(user,password) False User/password from API getConnection(user,password) True Current WLS user If a simple getConnection() is used or database credentials are enabled, the current user that is authenticated to the WLS system is checked. If database credentials are not enabled, then the user and password on the API are used. Example The following is an actual example of the interactions between identity-based-connection-pooling-enabled, oracle-proxy-session, and use-database-credentials. On the database side, the following objects are configured.- Database users scott; jdbcqa; jdbcqa3- Permission for proxy: alter user jdbcqa3 grant connect through jdbcqa;- Permission for proxy: alter user jdbcqa grant connect through jdbcqa; The following WebLogic Data Source objects are configured.- Users weblogic, wluser- Credential mapping “weblogic” to “scott”- Credential mapping "wluser" to "jdbcqa3"- Data source descriptor configured with user “jdbcqa”- All tests are run with Set Client ID set to true (more about that below).- All tests are run with oracle-proxy-session set to false (more about that below). The test program:- Runs in servlet- Authenticates to WLS as user “weblogic” Use DB Credentials Identity based getConnection(scott,***) getConnection(weblogic,***) getConnection(jdbcqa3,***) getConnection()  true  true Identity scottClient weblogicProxy null weblogic fails - not a db user User jdbcqa3Client weblogicProxy null Default user jdbcqaClient weblogicProxy null  false  true scott fails - not a WLS user User scottClient scottProxy null jdbcqa3 fails - not a WLS user User scottClient scottProxy null  true  false Proxy for scott fails weblogic fails - not a db user User jdbcqa3Client weblogicProxy jdbcqa Default user jdbcqaClient weblogicProxy null  false  false scott fails - not a WLS user Default user jdbcqaClient scottProxy null jdbcqa3 fails - not a WLS user Default user jdbcqaClient scottProxy null If Set Client ID is set to false, all cases would have Client set to null. If this was not an Oracle thin driver, the one case with the non-null Proxy in the above table would throw an exception because proxy session is only supported, implicitly or explicitly, with the Oracle thin driver. When oracle-proxy-session is set to true, the only cases that will pass (with a proxy of "jdbcqa") are the following.1. Setting use-database-credentials to true and doing getConnection(jdbcqa3,…) or getConnection().2. Setting use-database-credentials to false and doing getConnection(wluser, …) or getConnection(). Summary There are many options to choose from for data source security.  Considerations include the number and volatility of WLS and Database users, the granularity of data access, the depth of the security identity (property on the connection or a real user), performance, coordination of various components in the software stack, and driver capabilities.  Now that you have the big picture (remember that table in part 1), you can make a more informed choice.

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• Right-Time Retail Part 2

  - by David Dorf

  This is part two of the three-part series. Normal 0 false false false EN-US X-NONE X-NONE /* 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:0in 5.4pt 0in 5.4pt; mso-para-margin-top:0in; mso-para-margin-right:0in; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0in; 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;} Right-Time Integration Of course these real-time enabling technologies are only as good as the systems that utilize them, and it only takes one bottleneck to slow everyone else down. What good is an immediate stock-out notification if the supply chain can’t react until tomorrow? Since being formed in 2006, Oracle Retail has been not only adding more integrations between systems, but also modernizing integrations for appropriate speed. Notice I tossed in the word “appropriate.” Not everything needs to be real-time – again, we’re talking about Right-Time Retail. The speed of data capture, analysis, and execution must be synchronized or you’re wasting effort. Unfortunately, there isn’t an enterprise-wide dial that you can crank-up for your estate. You’ll need to improve things piecemeal, with people and processes as limiting factors while choosing the appropriate types of integrations. There are three integration styles we see in the retail industry. First is batch. I know, the word “batch” just sounds slow, but this pattern is less about velocity and more about volume. When there are large amounts of data to be moved, you’ll want to use batch processes. Our technology of choice here is Oracle Data Integrator (ODI), which provides a fast version of Extract-Transform-Load (ETL). Instead of the three-step process, the load and transform steps are combined to save time. ODI is a key technology for moving data into Retail Analytics where we can apply science. Performing analytics on each sale as it occurs doesn’t make any sense, so we batch up a statistically significant amount and submit all at once. The second style is fire-and-forget. For some types of data, we want the data to arrive ASAP but immediacy is not necessary. Speed is less important than guaranteed delivery, so we use message-oriented middleware available in both Weblogic and the Oracle database. For example, Point-of-Service transactions are queued for delivery to Central Office at corporate. If the network is offline, those transactions remain in the queue and will be delivered when the network returns. Transactions cannot be lost and they must be delivered in order. (Ever tried processing a return before the sale?) To enhance the standard queues, we offer the Retail Integration Bus (RIB) to help the management and monitoring of fire-and-forget messaging in the enterprise. The third style is request-response and is most commonly implemented as Web services. This is a synchronous message where the sender waits for a response. In this situation, the volume of data is small, guaranteed delivery is not necessary, but speed is very important. Examples include the website checking inventory, a price lookup, or processing a credit card authorization. The Oracle Service Bus (OSB) typically handles the routing of such messages, and we’ve enhanced its abilities with the Retail Service Backbone (RSB). To better understand these integration patterns and where they apply within the retail enterprise, we’re providing the Retail Reference Library (RRL) at no charge to Oracle Retail customers. The library is composed of a large number of industry business processes, including those necessary to support Commerce Anywhere, as well as detailed architectural diagrams. These diagrams allow implementers to understand the systems involved in integrations and the specific data payloads. Furthermore, with our upcoming release we’ll be providing a new tool called the Retail Integration Console (RIC) that allows IT to monitor and manage integrations from a single point. Using RIC, retailers can quickly discern where integration activity is occurring, volume statistics, average response times, and errors. The dashboards provide the ability to dive down into the architecture documentation to gather information all the way down to the specific payload. Retailers that want real-time integrations will also need real-time monitoring of those integrations to ensure service-level agreements are maintained. Part 3 looks at marketing.

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• Understanding the 'High Performance' meaning in Extreme Transaction Processing

  - by kyap

  Despite my previous blogs entries on SOA/BPM and Identity Management, the domain where I'm the most passionated is definitely the Extreme Transaction Processing, commonly called XTP.I came across XTP back to 2007 while I was still FMW Product Manager in EMEA. At that time Oracle acquired a company called Tangosol, which owned an unique product called Coherence that we renamed to Oracle Coherence. Beside this innovative renaming of the product, to be honest, I didn't know much about it, except being a "distributed in-memory cache for Extreme Transaction Processing"... not very helpful still.In general when people doesn't fully understand a technology or a concept, they tend to find some shortcuts, either correct or not, to justify their lack-of understanding... and of course I was part of this category of individuals. And the shortcut was "Oracle Coherence Cache helps to improve Performance". Excellent marketing slogan... but not very meaningful still. By chance I was able to get away quickly from that group in July 2007* at Thames Valley Park (UK), after I attended one of the most interesting workshops, in my 10 years career in Oracle, delivered by Brian Oliver. The biggest mistake I made was to assume that performance improvement with Coherence was related to the response time. Which can be considered as legitimus at that time, because after-all caches help to reduce latency on cached data access, hence reduce the response-time. But like all caches, you need to define caching and expiration policies, thinking about the cache-missed strategy, and most of the time you have to re-write partially your application in order to work with the cache. At a result, the expected benefit vanishes... so, not very useful then?The key mistake I made was my perception or obsession on how performance improvement should be driven, but I strongly believe this is still a common problem to most of the developers. In fact we all know the that the performance of a system is generally presented by the Capacity (or Throughput), with the 2 important dimensions Speed (response-time) and Volume (load) :Capacity (TPS) = Volume (T) / Speed (S)To increase the Capacity, we can either reduce the Speed(in terms of response-time), or to increase the Volume. However we tend to only focus on reducing the Speed dimension, perhaps it is more concrete and tangible to measure, and nicer to present to our management because there's a direct impact onto the end-users experience. On the other hand, we assume the Volume can be addressed by the underlying hardware or software stack, so if we need more capacity (scale out), we just add more hardware or software. Unfortunately, the reality proves that IT is never as ideal as we assume...The challenge with Speed improvement approach is that it is generally difficult and costly to make things already fast... faster. And by adding Coherence will not necessarily help either. Even though we manage to do so, the Capacity can not increase forever because... the Speed can be influenced by the Volume. For all system, we always have a performance illustration as follow: In all traditional system, the increase of Volume (Transaction) will also increase the Speed (Response-Time) as some point. The reason is simple: most of the time the Application logics were not designed to scale. As an example, if you have a while-loop in your application, it is natural to conceive that parsing 200 entries will require double execution-time compared to 100 entries. If you need to "Speed-up" the execution, you can only upgrade your hardware (scale-up) with faster CPU and/or network to reduce network latency. It is technically limited and economically inefficient. And this is exactly where XTP and Coherence kick in. The primary objective of XTP is about designing applications which can scale-out for increasing the Volume, by applying coding techniques to keep the execution-time as constant as possible, independently of the number of runtime data being manipulated. It is actually not just about having an application running as fast as possible, but about having a much more predictable system, with constant response-time and linearly scale, so we can easily increase throughput by adding more hardwares in parallel. It is in general combined with the Low Latency Programming model, where we tried to optimize the network usage as much as possible, either from the programmatic angle (less network-hoops to complete a task), and/or from a hardware angle (faster network equipments). In this picture, Oracle Coherence can be considered as software-level XTP enabler, via the Distributed-Cache because it can guarantee: - Constant Data Objects access time, independently from the number of Objects and the Coherence Cluster size - Data Objects Distribution by Affinity for in-memory data grouping - In-place Data Processing for parallel executionTo summarize, Oracle Coherence is indeed useful to improve your application performance, just not in the way we commonly think. It's not about the Speed itself, but about the overall Capacity with Extreme Load while keeping consistant Speed. In the future I will keep adding new blog entries around this topic, with some sample codes experiences sharing that I capture in the last few years. In the meanwhile if you want to know more how Oracle Coherence, I strongly suggest you to start with checking how our worldwide customers are using Oracle Coherence first, then you can start playing with the product through our tutorial.Have Fun !

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• Avoiding coupling

  - by Seralize

  It is also true that a system may become so coupled, where each class is dependent on other classes that depend on other classes, that it is no longer possible to make a change in one place without having a ripple effect and having to make subsequent changes in many places.[1] This is why using an interface or an abstract class can be valuable in any object-oriented software project. Quote from Wikipedia Starting from scratch I'm starting from scratch with a project that I recently finished because I found the code to be too tightly coupled and hard to refactor, even when using MVC. I will be using MVC on my new project aswell but want to try and avoid the pitfalls this time, hopefully with your help. Project summary My issue is that I really wish to keep the Controller as clean as possible, but it seems like I can't do this. The basic idea of the program is that the user picks wordlists which is sent to the game engine. It will pick random words from the lists until there are none left. Problem at hand My main problem is that the game will have 'modes', and need to check the input in different ways through a method called checkWord(), but exactly where to put this and how to abstract it properly is a challenge to me. I'm new to design patterns, so not sure whether there exist any might fit my problem. My own attempt at abstraction Here is what I've gotten so far after hours of 'refactoring' the design plans, and I know it's long, but it's the best I could do to try and give you an overview (Note: As this is the sketch, anything is subject to change, all help and advice is very welcome. Also note the marked coupling points): Wordlist class Wordlist { // Basic CRUD etc. here! // Other sample methods: public function wordlistCount($user_id) {} // Returns count of how many wordlists a user has public function getAll($user_id) {} // Returns all wordlists of a user } Word class Word { // Basic CRUD etc. here! // Other sample methods: public function wordCount($wordlist_id) {} // Returns count of words in a wordlist public function getAll($wordlist_id) {} // Returns all words from a wordlist public function getWordInfo($word_id) {} // Returns information about a word } Wordpicker class Wordpicker { // The class needs to know which words and wordlists to exclude protected $_used_words = array(); protected $_used_wordlists = array(); // Wordlists to pick words from protected $_wordlists = array(); /* Public Methods */ public function setWordlists($wordlists = array()) {} public function setUsedWords($used_words = array()) {} public function setUsedWordlists($used_wordlists = array()) {} public function getRandomWord() {} // COUPLING POINT! Will most likely need to communicate with both the Wordlist and Word classes /* Protected Methods */ protected function _checkAvailableWordlists() {} // COUPLING POINT! Might need to check if wordlists are deleted etc. protected function _checkAvailableWords() {} // COUPLING POINT! Method needs to get all words in a wordlist from the Word class } Game class Game { protected $_session_id; // The ID of a game session which gets stored in the database along with game details protected $_game_info = array(); // Game instantiation public function __construct($user_id) { if (! $this->_session_id = $this->_gameExists($user_id)) { // New game } else { // Resume game } } // This is the method I tried to make flexible by using abstract classes etc. // Does it even belong in this class at all? public function checkWord($answer, $native_word, $translation) {} // This method checks the answer against the native word / translation word, depending on game mode public function getGameInfo() {} // Returns information about a game session, or creates it if it does not exist public function deleteSession($session_id) {} // Deletes a game session from the database // Methods dealing with game session information protected function _gameExists($user_id) {} protected function _getProgress($session_id) {} protected function _updateProgress($game_info = array()) {} } The Game /* CONTROLLER */ /* "Guess the word" page */ // User input $game_type = $_POST['game_type']; // Chosen with radio buttons etc. $wordlists = $_POST['wordlists']; // Chosen with checkboxes etc. // Starts a new game or resumes one from the database $game = new Game($_SESSION['user_id']); $game_info = $game->getGameInfo(); // Instantiates a new Wordpicker $wordpicker = new Wordpicker(); $wordpicker->setWordlists((isset($game_info['wordlists'])) ? $game_info['wordlists'] : $wordlists); $wordpicker->setUsedWordlists((isset($game_info['used_wordlists'])) ? $game_info['used_wordlists'] : NULL); $wordpicker->setUsedWords((isset($game_info['used_words'])) ? $game_info['used_words'] : NULL); // Fetches an available word if (! $word_id = $wordpicker->getRandomWord()) { // No more words left - game over! $game->deleteSession($game_info['id']); redirect(); } else { // Presents word details to the user $word = new Word(); $word_info = $word->getWordInfo($word_id); } The Bit to Finish /* CONTROLLER */ /* "Check the answer" page */ // ?????????????????? ( http://pastebin.com/cc6MtLTR ) Make sure you toggle the 'Layout Width' to the right for a better view. Thanks in advance. Questions To which extent should objects be loosely coupled? If object A needs info from object B, how is it supposed to get this without losing too much cohesion? As suggested in the comments, models should hold all business logic. However, as objects should be independent, where to glue them together? Should the model contain some sort of "index" or "client" area which connects the dots? Edit: So basically what I should do for a start is to make a new model which I can more easily call with oneliners such as $model->doAction(); // Lots of code in here which uses classes! How about the method for checking words? Should it be it's own object? I'm not sure where I should put it as it's pretty much part of the 'game'. But on another hand, I could just leave out the 'abstraction and OOPness' and make it a method of the 'client model' which will be encapsulated from the controller anyway. Very unsure about this.

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• iOS Support with Windows Azure Mobile Services – now with Push Notifications

  - by ScottGu

  A few weeks ago I posted about a number of improvements to Windows Azure Mobile Services. One of these was the addition of an Objective-C client SDK that allows iOS developers to easily use Mobile Services for data and authentication.  Today I'm excited to announce a number of improvement to our iOS SDK and, most significantly, our new support for Push Notifications via APNS (Apple Push Notification Services).  This makes it incredibly easy to fire push notifications to your iOS users from Windows Azure Mobile Service scripts. Push Notifications via APNS We've provided two complete tutorials that take you step-by-step through the provisioning and setup process to enable your Windows Azure Mobile Service application with APNS (Apple Push Notification Services), including all of the steps required to configure your application for push in the Apple iOS provisioning portal: Getting started with Push Notifications - iOS Push notifications to users by using Mobile Services - iOS Once you've configured your application in the Apple iOS provisioning portal and uploaded the APNS push certificate to the Apple provisioning portal, it's just a matter of uploading your APNS push certificate to Mobile Services using the Windows Azure admin portal: Clicking the “upload” within the “Push” tab of your Mobile Service allows you to browse your local file-system and locate/upload your exported certificate.  As part of this you can also select whether you want to use the sandbox (dev) or production (prod) Apple service: Now, the code to send a push notification to your clients from within a Windows Azure Mobile Service is as easy as the code below: push.apns.send(deviceToken, {      alert: 'Toast: A new Mobile Services task.',      sound: 'default' }); This will cause Windows Azure Mobile Services to connect to APNS (Apple Push Notification Service) and send a notification to the iOS device you specified via the deviceToken: Check out our reference documentation for full details on how to use the new Windows Azure Mobile Services apns object to send your push notifications. Feedback Scripts An important part of working with any PNS (Push Notification Service) is handling feedback for expired device tokens and channels. This typically happens when your application is uninstalled from a particular device and can no longer receive your notifications. With Windows Notification Services you get an instant response from the HTTP server.  Apple’s Notification Services works in a slightly different way and provides an additional endpoint you can connect to poll for a list of expired tokens. As with all of the capabilities we integrate with Mobile Services, our goal is to allow developers to focus more on building their app and less on building infrastructure to support their ideas. Therefore we knew we had to provide a simple way for developers to integrate feedback from APNS on a regular basis.  This week’s update now includes a new screen in the portal that allows you to optionally provide a script to process your APNS feedback – and it will be executed by Mobile Services on an ongoing basis: This script is invoked periodically while your service is active. To poll the feedback endpoint you can simply call the apns object's getFeedback method from within this script: push.apns.getFeedback({       success: function(results) {           // results is an array of objects with a deviceToken and time properties      } }); This returns you a list of invalid tokens that can now be removed from your database. iOS Client SDK improvements Over the last month we've continued to work with a number of iOS advisors to make improvements to our Objective-C SDK. The SDK is being developed under an open source license (Apache 2.0) and is available on github. Many of the improvements are behind the scenes to improve performance and memory usage. However, one of the biggest improvements to our iOS Client API is the addition of an even easier login method.  Below is the Objective-C code you can now write to invoke it: [client loginWithProvider:@"twitter"                     onController:self                        animated:YES                      completion:^(MSUser *user, NSError *error) {      // if no error, you are now logged in via twitter }]; This code will automatically present and dismiss our login view controller as a modal dialog on the specified controller.  This does all the hard work for you and makes login via Twitter, Google, Facebook and Microsoft Account identities just a single line of code. My colleague Josh just posted a short video demonstrating these new features which I'd recommend checking out: Summary The above features are all now live in production and are available to use immediately.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using Mobile Services today. Visit the Windows Azure Mobile Developer Center to learn more about how to build apps with Mobile Services. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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