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• Achieving decoupling in Model classes

  - by Guven

  I am trying to test-drive (or at least write unit tests) my Model classes but I noticed that my classes end up being too coupled. Since I can't break this coupling, writing unit tests is becoming harder and harder. To be more specific: Model Classes: These are the classes that hold the data in my application. They resemble pretty much the POJO (plain old Java objects), but they also have some methods. The application is not too big so I have around 15 model classes. Coupling: Just to give an example, think of a simple case of Order Header - Order Item. The header knows the item and the item knows the header (needs some information from the header for performing certain operations). Then, let's say there is the relationship between Order Item - Item Report. The item report needs the item as well. At this point, imagine writing tests for Item Report; you need have a Order Header to carry out the tests. This is a simple case with 3 classes; things get more complicated with more classes. I can come up with decoupled classes when I design algorithms, persistence layers, UI interactions, etc... but with model classes, I can't think of a way to separate them. They currently sit as one big chunk of classes that depend on each other. Here are some workarounds that I can think of: Data Generators: I have a package that generates sample data for my model classes. For example, the OrderHeaderGenerator class creates OrderHeaders with some basic data in it. I use the OrderHeaderGenerator from my ItemReport unit-tests so that I get an instance to OrderHeader class. The problem is these generators get complicated pretty fast and then I also need to test these generators; defeating the purpose a little bit. Interfaces instead of dependencies: I can come up with interfaces to get rid of the hard dependencies. For example, the OrderItem class would depend on the IOrderHeader interface. So, in my unit tests, I can easily mock the behaviour of an OrderHeader with a FakeOrderHeader class that implements the IOrderHeader interface. The problem with this approach is the complexity that the Model classes would end up having. Would you have other ideas on how to break this coupling in the model classes? Or, how to make it easier to unit-test the model classes?

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• Bootloader Problems Grub Won't Load Windows 7

  - by user108805

  I sent this to [email protected], still no response thought I could get a faster solution here. I am running Windows 7 64-bit and Ubuntu 12.04 LTS on separate partitions. The message is sent is: Boot-Repair URL: http://paste.ubuntu.com/1365163/ Originally I was unable to access Ubuntu after a windows update (Ubuntu was installed using wubi). Rather than logging into Ubuntu from the Windows 7 Bootloader, it lead to the grub command prompt. No matter what I did here, it would not log me into linux. As a result I uninstalled Ubuntu from the Add/Remove Programs application in Windows 7. I then re-installed Ubuntu 12.04 LTS using a liveCD-USB. This time however, I created a partition. I then restarted and got the GRUB bootloader which loads Ubuntu 12.04 LTS with no problems, however when I select windows (listed as "Windows 7 (loader)"), it just refreshes the grub bootloader instead of loading Windows 7. I then used the Windows 7 repair disk to run bootrec/fixmbr and bootrec/fixboot. This led to no bootloader coming up when I started my computer. Instead I got a blank black screen with a flashing white cursor. I went on to do a bootrec/buildbcd and bootrec/scanos. These did nothing to change the situation. When I ran bootrec/scanos it said that no Windows 7 installations were present. After this I decided to reinstall WIndows 7 only for this to do nothing to change the situation. Afterwards I did a boot-repair in which I began to get the GRUB bootloader, which would load ubuntu 12.04 LTS, but still would not load Windows 7. I also did a sudo update-grub which recognized Windows 7 as being installed, but still didn't fix the issue of loading Windows 7. While running Ubuntu I have no problem accessing my WIndows 7 partition which is formatted as NTFS. It shows all the files and folders reflecting that the re-install did take place, and it also shows all of my old applications and folders in the Windows.old folder. I am completely stuck at this point and have no clue what I should do next. Any help you can offer me will be greatly appreciate. Thank You --gap

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• Loading levels from .txt or .XML for XNA

  - by Dave Voyles

  I'm attemptin to add multiple levels to my pong game. I'd like to simply exchange a few elements with each level, nothing crazy. Just the background texture, the color of the AI paddle (the one on the right side), and the music. It seems that the best way to go about this is by utilizing the StreamReader to read and write the files from XML. If there is a better, or more efficient alternative way then I'm all for it. In looking over the XNA Starter Platformer Kit provided by MS it seems that they've done it in this manner as well. I'm perplexed by a few things, however, namely parts within the Level class which aren't commented. /// <summary> /// Iterates over every tile in the structure file and loads its /// appearance and behavior. This method also validates that the /// file is well-formed with a player start point, exit, etc. /// </summary> /// <param name="fileStream"> /// A stream containing the tile data. /// </param> private void LoadTiles(Stream fileStream) { // Load the level and ensure all of the lines are the same length. int width; List<string> lines = new List<string>(); using (StreamReader reader = new StreamReader(fileStream)) { string line = reader.ReadLine(); width = line.Length; while (line != null) { lines.Add(line); if (line.Length != width) throw new Exception(String.Format("The length of line {0} is different from all preceeding lines.", lines.Count)); line = reader.ReadLine(); } } What does width = line.Length mean exactly? I mean I know how it reads the line, but what difference does it make if one line is longer than any of the others? Finally, their levels are simply text files that look like this: .................... .................... .................... .................... .................... .................... .................... .........GGG........ .........###........ .................... ....GGG.......GGG... ....###.......###... .................... .1................X. #################### It can't be that easy..... Can it?

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• F# Objects &ndash; Integrating with the other .Net Languages &ndash; Part 1

  - by MarkPearl

  In the next few blog posts I am going to explore objects in F#. Up to now, my dabbling in F# has really been a few liners and while I haven’t reached the point where F# is my language of preference – I am already seeing the benefits of the language when solving certain types of programming problems. For me I believe that the F# language will be used in a silo like architecture and that the real benefit of having F# under your belt is so that you can solve problems that F# lends itself towards and then interact with other .Net languages in doing the rest. When I was still very new to the F# language I did the following post covering how to get F# & C# to talk to each other. Today I am going to use a similar approach to demonstrate the structure of F# objects when inter-operating with other languages. Lets start with an empty F# class … type Person() = class end   Very simple, and all we really have done is declared an object that has nothing in it. We could if we wanted to make an object that takes a constructor with parameters… the code for this would look something like this… type Person =     {         Firstname : string         Lastname : string     }   What’s interesting about this syntax is when you try and interop with this object from another .Net language like C# - you would see the following…   Not only has a constructor been created that accepts two parameters, but Firstname and Lastname are also exposed on the object. Now it’s important to keep in mind that value holders in F# are immutable by default, so you would not be able to change the value of Firstname after the construction of the object – in C# terms it has been set to readonly. One could however explicitly state that the value holders were mutable, which would then allow you to change the values after the actual creation of the object. type Person = { mutable Firstname : string mutable Lastname : string }   Something that bugged me for a while was what if I wanted to have an F# object that requires values in its constructor, but does not expose them as part of the object. After bashing my head for a few moments I came up with the following syntax – which achieves this result. type Person(Firstname : string, Lastname : string) = member v.Fullname = Firstname + " " + Lastname What I haven’t figured out yet is what is the difference between the () & {} brackets when declaring an object.

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• OOF checklist

  - by Daniel Moth

  When going on vacation or otherwise being out of office (known as OOF in Microsoft), it is polite and professional that our absence creates the minimum disruption possible to the rest of the business, and especially our colleagues. Below is my OOF checklist - I try to do these as soon as I know I'll be OOF, rather than leave it for the night before. Let the relevant folks on the team know the planned dates of absence and check if anybody was expecting something from you during that timeframe. Reset expectations with them, and as applicable try to find another owner for individual activities that cannot wait. Go through your calendar for the OOF period and decline every meeting occurrence so the owner of the meeting knows that you won't be attending (similar to my post about responding to invites). If it is your meeting cancel it so that people don’t turn up without the meeting organizer being there. Do this even for meetings were the folks should know due to step #1. Over-communicating is a good thing here and keeps calendars all around up to date. Enter your OOF dates in whatever tool your company uses. Typically that is the notification to your manager. In your Outlook calendar, create a local Appointment (don't invite anyone) for the date range (All day event) setting the "Show As" dropdown to "Out of Office". This way, people won’t try to schedule meetings with you on that day. If you use Lync, set the status to "Off Work" for that period. If you won't be responding to email (which when on your vacation you definitely shouldn't) then in Outlook setup "Automatic Replies (Out of Office)" for that period. This way people won’t think you are rude when not replying to their emails. In your OOF message point to an alias (ideally of many people) as a fallback for urgent queries. If you want to proactively notify individuals of your OOFage then schedule and send a multi-day meeting request for the entire period. Remember to set the "Show As" to "Free" (so their calendar doesn’t show busy/oof to others), set the "Reminder" to "None" (so they don’t get a reminder about it), set "Low Importance", and uncheck both "Response Options" so if they don't want this on their calendar, it is just one click for them to get rid of it. Aside: I have another post with advice on sending invites. If you care about people who would not observe the above but could drop by your office, stick a physical OOF note at your office door or chair/monitor or desk. Have I missed any? Comments about this post by Daniel Moth welcome at the original blog.

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• Cone of Uncertainty in classic and agile projects

  - by DigiMortal

  David Starr from Scrum.org made interesting session in TechEd Europe 2012 - Implementing Scrum Using Team Foundation Server 2012. One of interesting things for me was how Cone of Uncertainty looks like in agile projects (or how agile methodologies distort the cone we know from waterfall projects). This posting illustrates two cones – one for waterfall and one for agile world. Cone of Uncertainty Cone of Uncertainty was introduced to software development community by Steve McConnell and it visualizes how accurate are our estimates over project timeline. Here is the Cone of Uncertainty when we deal with waterfall and Big Design Up-Front (BDUF). Cone of Uncertainty. Taken from MSDN Library page Estimating. The closer we are to project end the more accurate are our estimates. When project ends we know exactly how much every task took time. As we can see then cone is wide when we usually have to give our estimates – it happens somewhere between Initial Project Concept and Requirements Complete. Don’t ask me why Initial Project Concept is the stage where some companies give their best estimates – they just do it every time and doesn’t learn a thing later. This cone is inevitable for software development and agile methodologies that try to make software world better are also able to change the cone. Cone of Uncertainty in agile projects Agile methodologies usually try to avoid BDUF, waterfalls and other things that make all our mistakes highly expensive. Of course, we are not the only ones who make mistakes – don’t also forget our dear customers. Agile methodologies take development as creational work and focus on making it better. One main trick is to focus on small and short iterations. What it means? We are estimating functionalities that are easier for us to understand and implement. Therefore our estimates are more accurate. As we move from few big iterations to many small iterations we also distort and slice Cone of Uncertainty. This is how cone looks when agile methodologies are used. Cone of Uncertainty in agile projects. We have more cones to live with but they are way smaller. I don’t have any numbers to put here because I found any but still this “chart” should give you the point: more smaller iterations cause more but way smaller cones of uncertainty. We can handle these small uncertainties because steps we take to complete small tasks are more predictable and doesn’t grow very often above our heads. One more note. Consider that both of charts given in this posting describe exactly the same phase of same project – just uncertainties are different.

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• What to do when you inherit an unmaintainable codebase?

  - by GordonM

  I'm currently working at a company with 2 other PHP developers aside from me, and 1 junior developer. The senior developer who originally built the system we're all working on has resigned and will only be here for a matter of weeks. The other developer, who is the only other guy who knows anything about the system, is unhappy here and is looking for a new job. I'm very real danger of being left behind as the only experienced developer on this codebase. Since I've joined this company I've tried to push for better coding standards, project documentation, etc and I do think I've made some headway, but the vast majority of the code is simply unmaintainable and uncommented. A lot of this has to do with the need to get things done fast at points in the project before I joined, but now the technical debt is enormous, even with the two developers who do understand the system on board. Without them, it will simply be impossible to do anything with it. The senior developer is working on trying to at least comment all his code before he leaves but I think the codebase is simply too vast to properly document in the remaining time. Besides, when he does comment it still doesn't make things as clear as it could. If the system was better organized and documented I could probably start refactoring it incrementally, but the whole thing is so tightly coupled that it's very difficult to make any changes in one module without having unintended knock-on effects in other modules. Naturally, there's no unit tests either, and I honestly don't think this codebase could possibly be unit tested anyway given how it's implemented. There also never seems to be enough time to get things done even with 3 developers and 1 junior developer. With one developer and one junior, neither of which had significant input into the early design of the system, I don't see how we could possibly get anything done with keeping the current system working, implementing new features as needed and developing a replacement for the current codebase that is better organized. Is there an approach I can take to cope with this situation, or should I be getting my own CV in order as well at this point? If it was just me and the junior designer who would be left I'd go for the latter option almost without question. However, there's a team of front-end developers and content managers as well, and I'm worried what would become of them if I left and put them in a position where there would be no developers at all. The department might just be closed down altogether under such circumstances, and then I'd have their unemployment on my conscience as well!

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• Collision in PyGame for spinning rectangular object.touching circles

  - by OverAchiever

  I'm creating a variation of Pong. One of the differences is that I use a rectangular structure as the object which is being bounced around, and I use circles as paddles. So far, all the collision handling I've worked with was using simple math (I wasn't using the collision "feature" in PyGame). The game is contained within a 2-dimensional continuous space. The idea is that the rectangular structure will spin at different speed depending on how far from the center you touch it with the circle. Also, any extremity of the rectangular structure should be able to touch any extremity of the circle. So I need to keep track of where it has been touched on both the circle and the rectangle to figure out the direction it will be bounced to. I intend to have basically 8 possible directions (Up, down, left, right and the half points between each one of those). I can work out the calculation of how the objected will be dislocated once I get the direction it will be dislocated to based on where it has been touch. I also need to keep track of where it has been touched to decide if the rectangular structure will spin clockwise or counter-clockwise after it collided. Before I started coding, I read the resources available at the PyGame website on the collision class they have (And its respective functions). I tried to work out the logic of what I was trying to achieve based on those resources and how the game will function. The only thing I could figure out that I could do was to make each one of these objects as a group of rectangular objects, and depending on which rectangle was touched the other would behave accordingly and give the illusion it is a single object. However, not only I don't know if this will work, but I also don't know if it is gonna look convincing based on how PyGame redraws the objects. Is there a way I can use PyGame to handle these collision detections by still having a single object? Can I figure out the point of collision on both objects using functions within PyGame precisely enough to achieve what I'm looking for? P.s: I hope the question was specific and clear enough. I apologize if there were any grammar mistakes, English is not my native language.

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• external USB HD doesn't show up on 'sudo fdisk -l' on one Ubuntu, shows up on another (both 'precise')

  - by Menelaos

  I have a 1.5TB WD external USB HDD and two Ubuntu systems, both 'precise'. When I plug the disk on system A it doesn't show up on the output of sudo fdisk -l nor is it automatically mounted (note that that wasn't always the case - it used to appear in the past). When I plug it on system B (again Ubuntu precise) it shows up when I do a sudo fdisk -l (output appended at the end) and mounts automatically just fine. What does this discrepancy point to and what kind of diagnostics should I run / tools I should use to troubleshoot the problem? I followed the suggestion I received to do a sudo tail -f /var/log/syslog and the output is the following when I plug, unplug and replug the USB cable on System A: Sep 14 23:27:09 thorin mtp-probe: checking bus 2, device 3: "/sys/devices/pci0000:00/0000:00:13.2/usb2/2-2" Sep 14 23:27:09 thorin mtp-probe: bus: 2, device: 3 was not an MTP device Sep 14 23:28:01 thorin kernel: [ 338.994295] usb 2-2: USB disconnect, device number 3 Sep 14 23:28:04 thorin kernel: [ 341.808139] usb 2-2: new high-speed USB device number 4 using ehci_hcd Sep 14 23:28:04 thorin mtp-probe: checking bus 2, device 4: "/sys/devices/pci0000:00/0000:00:13.2/usb2/2-2" Sep 14 23:28:04 thorin mtp-probe: bus: 2, device: 4 was not an MTP device Sep 14 23:29:54 thorin AptDaemon: INFO: Quitting due to inactivity Sep 14 23:29:54 thorin AptDaemon: INFO: Quitting was requested (I guess the last two message are irrelevant). Output of sudo fdisk -l on System B $ sudo fdisk -l Disk /dev/sda: 1500.3 GB, 1500301910016 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00070db4 Device Boot Start End Blocks Id System /dev/sda1 * 2048 2905114623 1452556288 83 Linux /dev/sda2 2905116670 2930276351 12579841 5 Extended /dev/sda5 2905116672 2930276351 12579840 82 Linux swap / Solaris Disk /dev/sdb: 250.1 GB, 250059350016 bytes 255 heads, 63 sectors/track, 30401 cylinders, total 488397168 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x9c849c84 Device Boot Start End Blocks Id System /dev/sdb1 * 63 488375999 244187968+ 7 HPFS/NTFS/exFAT Disk /dev/sdg: 1500.3 GB, 1500299395072 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930272256 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x0003e17f Device Boot Start End Blocks Id System /dev/sdg1 2048 2930272255 1465135104 7 HPFS/NTFS/exFAT

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• following a moving sprite

  - by iQue

  Im trying to get my enemies to follow my main-character of the game (2D), but for some reason the game starts lagging like crazy when I do it the way I want to do it, and the following-part dosnt work 100% either, its just 1/24 enemies that comes to my sprite, the other 23 move towards it but stay at a certain point. Might be a poor explenation but dont know how else to put it. Code for moving my enemies: private int enemyX(){ int x = 0; for (int i = 0; i < enemies.size(); i++){ if (controls.pointerPosition.x > enemies.get(i).getX()){//pointerPosition is the position of my main-sprite. x = 5; } else{ x=-5; } Log.d(TAG, "happyX HERE: " + controls.pointerPosition.x); Log.d(TAG, "enemyX HERE: " + enemies.get(i).getX()); } return x; } private int enemyY(){ int y = 0; for (int i = 0; i < enemies.size(); i++){ if (controls.pointerPosition.y > enemies.get(i).getY()){ y = 5; } else{ y=-5; } } return y; } I send it to the update-method in my Enemy-class: private void drawEnemy(Canvas canvas){ addEnemies(); // a method where I add enemies to my arrayList, no parameters except bitmap. for(int i = 0; i < enemies.size(); i++){ enemies.get(i).update(enemyX(), enemyY()); } for(int i = 0; i < enemies.size(); i++){ enemies.get(i).draw(canvas); } } and finally, the update-method itself, located in my Enemy-class: public void update(int velX, int velY) { x += velX; //sets x before I draw y += velY; //sets y before I draw currentFrame = ++currentFrame % BMP_COLUMNS; } So can any1 figure out why it starts lagging so much and how I can fix it? Thanks for your time!

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• Pro SharePoint 2010 Business Intelligence Solutions

  - by Sahil Malik

  Ad:: SharePoint 2007 Training in .NET 3.5 technologies (more information). Oh yeah baby, it’s out finally! This book is what I wanted to write for so long now, but never really got a chance to. For SharePoint 2007, I authored the SharePoint section of “Smart BI Solutions with SQL Server 2008” for MS Press. But never really got the time, to author a full book that this topic deserved. Until SharePoint 2010, we actually have a full book on this topic. So first things first, I didn’t actually write it. My role was limited to the overall concept, the outline, the layout, completion of it, code samples, identifying what we need in here, vouching for technical accuracy, identifying authors etc. The real work was done by Srini (5 chapters), and Steve (1 chapter). So credit given where it is due. But, with that said, this is a pretty good book. It has always been a challenge to find the superman that knows both, data ware housing concepts, and SharePoint concepts. The data ware housing concepts include basic stuff you need to know to work in the BI area such as cubes, MDX queries, etc. So chapter 1 covers that – and if you’re a hardcore DBA, feel free to skip Chapter 1. Then beyond that, we take every single SharePoint 2010 BI topic, and slice and dice it in detail. The topics we deal with are - Visio Services Reporting services Business Connectivity Services Excel Services PerformancePoint Services And in covering each of these topics, we ensure that a general layout was followed for each topic, to ensure completeness of content. We make sure we cover Setup related issues and advice Point and click usage Code usage, i.e. extensibility using visual studio and a walkthrough of the administration side of things, including powershell. (Yes, I insisted on that in being there in every chapter). Writing a book is always a lot of work, so we hope you find it useful. And it should go very well with the other book I just reviewed, which is Microsoft ADO.NET 4, step by step. Comment on the article ....

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• Criteria for selecting timeout value?

  - by stijn

  Situation: a piece of software reads frames of data from a file in a seperate thread and puts it on a queue, emptied by another thread. That second thread periodically checks on the queue and fails rather gracefully, by showing an error message stating the read timed out, if no data is available within a certain amount of time. Initially this timeout was set to 200mSec. There was no real reasoning behind that constant though, but it worked fine. We measured on a couple of machines and for large data frames, larger than what would be used by customers, a read took like 20mSec whith no other load on the machine. However one customer now gets timeout errors now and then (on the second try all is fine, probably the file is in cache or the virus scanner leaves it alone). The programmers are like 'well, yeah, but that customer's machine is full of cruft, virus scanners, tons of unneeded background processes etc'. Of course the customer is like 'hey this should just work, shouldn't it'? While the programers have a point, since the software is heavy enough to validate the need for a dedicated machine, that does not make the customer happy. Increasing the timeout to 2 seconds, for example, solves the problem. But I'd like to make a proper decision now instead of just randomly pick some magic constant that is probably ok in 99% of cases. What criteria should be used for that? We could just pick a large number, but that feels wrong. (and then we end up with a program that has the horrible bahaviour of hanging when trying to read from a disconnected drive for instance, whereas we'd rather make it show an error right away). Or we could make the timeout value a user setting, but then we need to ducument it clearly and even then not all customers are tech savy enough to really understand what it does. Or we could try and wait until another customer reports timeouts and increase the value again. And again. Until we find something ok for 99.99% of the cases.. Any good practice for this type of situation?

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• Got Samba, Got PyNeighbourhood but still no connection. What else do I need?

  - by Frank A

  I am sure I had already hit post before but then could only find it by backing through browser. Was it deleted? is the question too dumb, sorry that I do not know the right jargon just trying to get answers to my problem anyway have reworded stuff a bit This seems to be a number one requirement for lots of people and 2 months on from setting up my Ubuntu pc, I am still unable to get a lasting connection in either direction. Adding a windows pc to a network is so easy... just a few clicks and get on with using it all. Using all command approaches and modifying configuration files is hardly user friendly. Googling brings up thousands of solutions but mostly they are too techy or assume the user is fully aware of how to use Linux. I do realise that their must be a lot of flavours for connecting to networks. So far I have installed Samba and fiddled with its config file. The day I did all that it worked from XP to Ubuntu. When I came back two days later to transfer my data over it would not connect. Although the the share does show up in Windows (XP) My Network Places. Today I installed PyNeighbourhood and this shows the Ubuntu box and all of the shares I had created at some point on Ubuntu and it even shows this under the XP workgroup name. But instructions on setting the connection up seem to relate to an earlier version and nothing seems to work there either. (I unshared most of those test folders but they still show up her but that is another question. When I click on mount- I can only click on one on the Ubuntu machine, there is one with no name so I assume this to be my attempt to add one XP Shared drive using ipaddress, I get errors. (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", (gksu:9767): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap", mount error(6): No such device or address Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) OK tried to find the manual referred to... only an old comment that manual would be produced for future versions. I saw in another thread that Winbind is needed as well or at least I assume as well? Totally lost again? Please help, what else needs to be installed to connect to win pcs on the network.

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• Behaviour Trees with irregular updates

  - by Robominister

  I'm interested in behaviour trees that aren't iterated every game tick, but every so often. (Edit: the tree could specify how many frames within the main game loop to wait before running its tick function again). Every theoretical implementation I have seen of behaviour trees talks of the tree search being carried out every game update - which seems necessary, because a leaf node (eg a behaviour, like 'return to base') needs to be constantly checked to see if is still running, failed or completed. Can anyone suggest how I might start implementing a tree that isnt run every tick, or point me in the direction of good material specific to this case (I am struggling to find anything)? My thoughts so far: action leaf nodes (when they start) must only push some kind of action object onto a list for an entity, rather than directly calling any code that makes the entity do something. The list of actions for the entity would be run every frame (update any that need to run, pop any that have completed from the list). the return state from a given action must be fed back into the tree, so that when we run the tree iteration again (and reach the same action leaf node - so the tree has so far determined that we ought to still be trying this action) - that the action has completed, or is still running etc. If my actual action code is running from an action list on an entity, then I possibly need to cancel previously running actions in the list - i am thinking that I can just delete the entire stack of queued up actions. I've seen the idea of ActionLists which block lower priority actions when a higher priority one is added, but this seems like very close logic to behaviour trees, and I dont want to be duplicating behaviour. This leaves me with some questions 1) How would I feed the action return state back into the tree? Its obvious I need to store some information relating to 'currently executing actions' on the entity, and check that in the tree tick, but I can't imagine how. 2) Does having a seperate behaviour tree (for deciding behaviour) and action list (for carrying out actual queued up actions) sound like a reasonable approach? 3) Is the approach of updating a behaviour tree irregularly actually used by anyone? It seems like a nice idea for budgeting ai search time when you have a lot of ai entities to process. (Edit) - I am also thinking about storing a single instance of a given behaviour tree in memory, and providing it by reference to any entity that uses it. So any information about what action was last selected for execution on an entity must be stored in a data context relative to the entity (which the tree can check). (I am probably answering my own questions as i go!) I hope I have expressed my questions adequately! Thanks in advance for any help :)

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• How are you coping with Ubuntu's Unity app launcher? (It auto-hides, can't minimize apps)

  - by Bad Learner

  [Firstly, let me tell you that this cannot be subjective in anyway, as I think at least Ubuntu beginners will have these questions boggling in their mind; and yes, this is a question that has a definite answer - - so, I am completely within the rules.] Okay, coming to the point, I see that Ubuntu uses Unity since v10.xx (netbook edition?) and carried the same to v11.04 & v11.10. As someone who's stuck to Windows for all these years, it's somewhat difficult to cope with Ubuntu's Unity, for the following reasons: [1] The Unity app launcher (to the screen's left) auto-hides when a window is maximized. [2]- And once launched, apps cannot be minimized by clicking the app's icon in the launcher. I have to go to the top-left of the screen and click the "_" button. I do know I can fix these issues by installing some configuration tool. But the thing is, if that's how it's meant to work, Canonical/Ubuntu would have designed it that way. But they didn't. Why? w.r.t above points [1], [2]: [1] EDITED: So, does it mean, it's good to work without maximizing the windows? Because if I maximize the window, the app launcher hides. And I need to hover the mouse to the left of the screen, wait a bit (even if it's a sec or even less, I can still feel the lag), and then click on the next app icon in the launcher to switch to it. I do know, I can use Alt+TAB to switch, but I am not sure which window comes next. This, I feel, isn't productive. Also, this makes me feel, Ubuntu is designed for large screens (it's nice on my 1920x1080p screen), because I can have two windows side-by-side or something like that on a large screen. This is not possible on smaller screens. [2]- Being able to minimize an application's window by clicking on its icon in the launcher (just like it works on Windows & probably elsewhere) would have been great, rather than having to go to the top-left and clicking the _ (minimize) button which brings up the app launcher itself (from hiding) most of the time. It's too tiring to have these small issues in the UI. I really would like to know how you are coping with these issues the way they are?

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• Quaternion based rotation and pivot position

  - by Michael IV

  I can't figure out how to perform matrix rotation using Quaternion while taking into account pivot position in OpenGL.What I am currently getting is rotation of the object around some point in the space and not a local pivot which is what I want. Here is the code [Using Java] Quaternion rotation method: public void rotateTo3(float xr, float yr, float zr) { _rotation.x = xr; _rotation.y = yr; _rotation.z = zr; Quaternion xrotQ = Glm.angleAxis((xr), Vec3.X_AXIS); Quaternion yrotQ = Glm.angleAxis((yr), Vec3.Y_AXIS); Quaternion zrotQ = Glm.angleAxis((zr), Vec3.Z_AXIS); xrotQ = Glm.normalize(xrotQ); yrotQ = Glm.normalize(yrotQ); zrotQ = Glm.normalize(zrotQ); Quaternion acumQuat; acumQuat = Quaternion.mul(xrotQ, yrotQ); acumQuat = Quaternion.mul(acumQuat, zrotQ); Mat4 rotMat = Glm.matCast(acumQuat); _model = new Mat4(1); scaleTo(_scaleX, _scaleY, _scaleZ); _model = Glm.translate(_model, new Vec3(_pivot.x, _pivot.y, 0)); _model =rotMat.mul(_model);//_model.mul(rotMat); //rotMat.mul(_model); _model = Glm.translate(_model, new Vec3(-_pivot.x, -_pivot.y, 0)); translateTo(_x, _y, _z); notifyTranformChange(); } Model matrix scale method: public void scaleTo(float x, float y, float z) { _model.set(0, x); _model.set(5, y); _model.set(10, z); _scaleX = x; _scaleY = y; _scaleZ = z; notifyTranformChange(); } Translate method: public void translateTo(float x, float y, float z) { _x = x - _pivot.x; _y = y - _pivot.y; _z = z; _position.x = _x; _position.y = _y; _position.z = _z; _model.set(12, _x); _model.set(13, _y); _model.set(14, _z); notifyTranformChange(); } But this method in which I don't use Quaternion works fine: public void rotate(Vec3 axis, float angleDegr) { _rotation.add(axis.scale(angleDegr)); // change to GLM: Mat4 backTr = new Mat4(1.0f); backTr = Glm.translate(backTr, new Vec3(_pivot.x, _pivot.y, 0)); backTr = Glm.rotate(backTr, angleDegr, axis); backTr = Glm.translate(backTr, new Vec3(-_pivot.x, -_pivot.y, 0)); _model =_model.mul(backTr);///backTr.mul(_model); notifyTranformChange(); }

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• How to keep a data structure synchronized over a network?

  - by David Gouveia

  Context In the game I'm working on (a sort of a point and click graphic adventure), pretty much everything that happens in the game world is controlled by an action manager that is structured a bit like: So for instance if the result of examining an object should make the character say hello, walk a bit and then sit down, I simply spawn the following code: var actionGroup = actionManager.CreateGroup(); actionGroup.Add(new TalkAction("Guybrush", "Hello there!"); actionGroup.Add(new WalkAction("Guybrush", new Vector2(300, 300)); actionGroup.Add(new SetAnimationAction("Guybrush", "Sit")); This creates a new action group (an entire line in the image above) and adds it to the manager. All of the groups are executed in parallel, but actions within each group are chained together so that the second one only starts after the first one finishes. When the last action in a group finishes, the group is destroyed. Problem Now I need to replicate this information across a network, so that in a multiplayer session, all players see the same thing. Serializing the individual actions is not the problem. But I'm an absolute beginner when it comes to networking and I have a few questions. I think for the sake of simplicity in this discussion we can abstract the action manager component to being simply: var actionManager = new List<List<string>>(); How should I proceed to keep the contents of the above data structure syncronized between all players? Besides the core question, I'm also having a few other concerns related to it (i.e. all possible implications of the same problem above): If I use a server/client architecture (with one of the players acting as both a server and a client), and one of the clients has spawned a group of actions, should he add them directly to the manager, or only send a request to the server, which in turn will order every client to add that group? What about packet losses and the like? The game is deterministic, but I'm thinking that any discrepancy in the sequence of actions executed in a client could lead to inconsistent states of the world. How do I safeguard against that sort of problem? What if I add too many actions at once, won't that cause problems for the connection? Any way to alleviate that?

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• Function like C# properties?

  - by alan2here

  I was directed here from SO as a better stack exchange site for this question. I've been thinking about the neatness and expression of C# properties over functions, although they only currently work where no parameters are used, and wondered. Is is possible, and if so why not, to have a stand alone function like C# property. For example: public class test { private byte n = 4; public test() { func = 2; byte n2 = func; func; } private byte func { get { return n; } set { n = value; } func { n++; } } } edit: Sorry for the vagueness first time round. I'm going to add some info and motivation. The 'n++' here is just a simple example, a placeholder, it's not intended to be representative of the actual code that would be used. I'm also looking at this from the point of view of looking at the property command as is, not in the context of using it for 'get_xyz' and 'set_xyz' member functions, which is certainly useful, but of instead comparing it more abstractly to functions and other programic elements. A 'get' property can be used instead of a function that takes no parameters, and syntactically they are perhaps only aesthetically, but as I see it noticeably nicer. However, properties also add the potential for an extra layer of polymorphism, one that relates to the 'func = 4;' getting, 'int n = func;' setting or 'func;' function like context in which they are used as well as the more common parameter based polymorphism. Potentially allowing for a lot of expression and contextual information reguarding how other would use your functions. As in many places uses and definitions would remain the same, it shouldn't break existing code. private byte func { get { } get bool { } set { } func { } func(bool) { } func(byte, myType) { } // etc... } So a read only function would look like this: private byte func { get { } } A normal function like this: private void func { func { } } A function with parameter polymorphism like this: private byte func { func(bool) { } func(byte, myType) { } } And a function that could return a value, or just compute, depending on the context it is used, that also has more conventional parameter polymorphism as well, like so: private byte func { get { } func(bool) { } func(byte, myType) { } }

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• How can I achieve a 3D-like effect with spritebatch's rotation and scale parameters

  - by Alic44

  I'm working on a 2d game with a top-down perspective similar to Secret of Mana and the 2D Final Fantasy games, with one big difference being that it's an action rpg using a 3-dimensional physics engine. I'm trying to draw an aimer graphic (basically an arrow) at my characters' feet when they're aiming a ranged weapon. At first I just converted the character's aim vector to radians and passed that into spritebatch, but there was a problem. The position of every object in my world is scaled for perspective when it's drawn to the screen. So if the physics engine coordinates are (1, 0, 1), the screen coords are actually (1, .707) -- the Y and Z axis are scaled by a perspective factor of .707 and then added together to get the screen coordinates. This meant that the direction the aimer graphic pointed (thanks to its rotation value passed into spritebatch) didn't match up with the direction the projectile actually traveled over time. Things looked fine when the characters fired left, right, up, or down, but if you fired on a diagonal the perspective of the physics engine didn't match with the simplistic way I was converting the character's aim direction to a screen rotation. Ok, fast forward to now: I've got the aimer's rotation matched up with the path the projectile will actually take, which I'm doing by decomposing a transform matrix which I build from two rotation matrices (one to represent the aimer's rotation, and one to represent the camera's 45 degree rotation on the x axis). My question is, is there a way to get not just rotation from a series of matrix transformations, but to also get a Vector2 scale which would give the aimer the appearance of being a 3d object, being warped by perspective? Orthographic perspective is what I'm going for, I think. So, the aimer arrow would get longer when facing sideways, and shorter when facing north and south because of the perspective. At the same time, it would get wider when facing north and south, and less wide when facing right or left. I'd like to avoid actually drawing the aimer texture in 3d because I'm still using spritebatch's layerdepth parameter at this point in my project, and I don't want to have to figure out how to draw a 3d object within the depth sorting system I already have. I can provide code and more details if this is too vague as a question... This is my first post on stack exchange. Thanks a lot for reading! Note: (I think) I realize it can't be a technically correct 3D perspective, because the spritebatch's vector2 scaling argument doesn't allow for an object to be skewed the way it actually should be. What I'm really interested in is, is there a good way to fake the effect, or should I just drop it and not scale at all? Edit to clarify without the help of a picture (apparently I can't post them yet): I want the aimer arrow to look like it has been painted on the ground at the character's feet, so it should appear to be drawn on the ground plane (in my case the XZ plane) which should be tilted at a 45 degree angle (around the X axis) from the viewing perspective. Alex

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• 4.8M wasn't enough so we went for 5.055M tpmc with Unbreakable Enterprise Kernel r2 :-)

  - by wcoekaer

  We released a new set of benchmarks today. One is an updated tpc-c from a few months ago where we had just over 4.8M tpmc at $0.98 and we just updated it to go to 5.05M and $0.89. The other one is related to Java Middleware performance. You can find the press release here. Now, I don't want to talk about the actual relevance of the benchmark numbers, as I am not in the benchmark team. I want to talk about why these numbers and these efforts, unrelated to what they mean to your workload, matter to customers. The actual benchmark effort is a very big, long, expensive undertaking where many groups work together as a big virtual team. Having the virtual team be within a single company of course helps tremendously... We already start with a very big server setup with tons of storage, many disks, lots of ram, lots of cpu's, cores, threads, large database setups. Getting the whole setup going to start tuning, by itself, is no easy task, but then the real fun starts with tuning the system for optimal performance -and- stability. A benchmark is not just revving an engine at high rpm, it's actually hitting the circuit. The tests require long runs, require surviving availability tests, such as surviving crashes -and- recovery under load. In the TPC-C example, the x4800 system had 4TB ram, 160 threads (8 sockets, hyperthreaded, 10 cores/socket), tons of storage attached, tons of luns visible to the OS. flash storage, non flash storage... many things at high scale that all have to be perfectly synchronized. During this process, we find bugs, we fix bugs, we find performance issues, we fix performance issues, we find interesting potential features to investigate for the future, we start new development projects for future releases and all this goes back into the products. As more and more customers, for Oracle Linux, are running larger and larger, faster and faster, more mission critical, higher available databases..., these things are just absolutely critical. Unrelated to what anyone's specific opinion is about tpc-c or tpc-h or specjenterprise etc, there is a ton of effort that the customer benefits from. All this work makes Oracle Linux and/or Oracle Solaris better platforms. Whether it's faster, more stable, more scalable, more resilient. It helps. Another point that I always like to re-iterate around UEK and UEK2 : we have our kernel source git repository online. Complete changelog of the mainline kernel, and our changes, easy to pull, easy to dissect, easy to know what went in when, why and where. No need to go log into a website and manually click through pages to hopefully discover changes or patches. No need to untar 2 tar balls and run a diff.

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• Wrapping REST based Web Service

  - by PaulPerry

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

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• Get AutoHotkey Script To Run As Admin At Startup

  - by deadlydog

  A few weeks back I posted some problems with running AutoHotkey (AHK) in Windows 8, and that the solution was to run your AHK script as admin.  I also showed how to have the script start automatically when you logged into Windows.  What I didn’t realize at the time though was that the method only worked because I had disabled UAC in the registry (which prevents most Metro apps from working in Windows 8, and likely isn’t acceptable for most people). So here is a Windows 8, UAC-friendly method to accomplish the same task (also works in previous versions of Windows).  The trick is to use the Task Scheduler: 1. Open the Task Scheduler (also known as “Schedule tasks” in Windows 8 Settings).   2. Create a new Basic Task. 3. Give it a name and description (something like “launch AutoHotkey script at login”), and then specify to have it run “When I log on”.  Then specify that you want it to “Start a program”, and then point it towards your AutoHotkey script.  Before you finish the wizard, check off “Open the Properties dialog for this task when I click Finish”.   4. When that Properties dialog opens up, go to the Conditions tab and make sure none of the checkboxes under the Power category are checked off; this will ensure the script still launches if you are on a laptop and not plugged into AC power.   5. Now here is the important part; To have your script “Run as admin”, on the General tab check off “Run with highest privileges”. Now your AHK script should start automatically as soon as you log into Windows; even when UAC is enabled   6. If your AHK script uses an #Include statement to include other files, you may get an error similar to this one when your task runs: “#Include file … cannot be opened. The program will exit.” The solution to this is to tell your AHK script to start in the same directory as the file that you want to include.  So you will need to edit your scheduled task’s Action to specify the Start In directory. Happy coding!

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• How granular should a command be in a CQ[R]S model?

  - by Aaronaught

  I'm considering a project to migrate part of our WCF-based SOA over to a service bus model (probably nServiceBus) and using some basic pub-sub to achieve Command-Query Separation. I'm not new to SOA, or even to service bus models, but I confess that until recently my concept of "separation" was limited to run-of-the-mill database mirroring and replication. Still, I'm attracted to the idea because it seems to provide all the benefits of an eventually-consistent system while sidestepping many of the obvious drawbacks (most notably the lack of proper transactional support). I've read a lot on the subject from Udi Dahan who is basically the guru on ESB architectures (at least in the Microsoft world), but one thing he says really puzzles me: As we get larger entities with more fields on them, we also get more actors working with those same entities, and the higher the likelihood that something will touch some attribute of them at any given time, increasing the number of concurrency conflicts. [...] A core element of CQRS is rethinking the design of the user interface to enable us to capture our users’ intent such that making a customer preferred is a different unit of work for the user than indicating that the customer has moved or that they’ve gotten married. Using an Excel-like UI for data changes doesn’t capture intent, as we saw above. -- Udi Dahan, Clarified CQRS From the perspective described in the quotation, it's hard to argue with that logic. But it seems to go against the grain with respect to SOAs. An SOA (and really services in general) are supposed to deal with coarse-grained messages so as to minimize network chatter - among many other benefits. I realize that network chatter is less of an issue when you've got highly-distributed systems with good message queuing and none of the baggage of RPC, but it doesn't seem wise to dismiss the issue entirely. Udi almost seems to be saying that every attribute change (i.e. field update) ought to be its own command, which is hard to imagine in the context of one user potentially updating hundreds or thousands of combined entities and attributes as it often is with a traditional web service. One batch update in SQL Server may take a fraction of a second given a good highly-parameterized query, table-valued parameter or bulk insert to a staging table; processing all of these updates one at a time is slow, slow, slow, and OLTP database hardware is the most expensive of all to scale up/out. Is there some way to reconcile these competing concerns? Am I thinking about it the wrong way? Does this problem have a well-known solution in the CQS/ESB world? If not, then how does one decide what the "right level" of granularity in a Command should be? Is there some "standard" one can use as a starting point - sort of like 3NF in databases - and only deviate when careful profiling suggests a potentially significant performance benefit? Or is this possibly one of those things that, despite several strong opinions being expressed by various experts, is really just a matter of opinion?

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• Attaching two objects and changing their world matrices accordingly

  - by A-Type

  I'm having a hard time wrapping my head around the transformations required to bind two objects together in either a two-way or one-way relationship. I will need to implement both types. For the first case, I want to be able to 'couple' two ships together in space. The ships have different mass, of course. Forces applied to either ship will use combined mass and moment of inertia to calculate and move both ships. The trick is, being sure that the point at which they are coupled remains the same, and they don't move at all relative to each other. The second case is similar: I want a ship to be able to enter the atmosphere of a planet and move relative to the planet. The planet will be orbiting the sun, which is fixed at 0,0,0. Essentially, when the ship is sitting still outside of the atmosphere, the planet will move past it on its course-- but when the ship is sitting still inside the atmosphere, it moves and rotates with the planet, so that it is always relative to the horizon. Essentially, the vertices which make up the ship are now transformed just like the ones that make up the planet, except that the ship can move itself around relative to the planet. I get the feeling I can implement both of these with the same code. Essentially, I am thinking of giving each object (which I call Fixtures) a list of "slave" Fixtures onto which that Fixture's world matrix is imposed. So, this would be the planet imposing its world on any contained ships. In the case of coupling, I would simply make each ship a slave of the other, somehow. Obviously I can't just multiply the ship's world matrix by the planet's, or each ship by the others. What I'd like some help with is what calculations to make in order to get a nice, seamless relative world to the other object. I was thinking maybe I could just multiply the world of the slave by the inverse of the master, but then when you couple two ships you would lose all that world data. So, perhaps I need an intermediate "world" which is the absolute world, but use a secondary "final world" to actually transform the objects?

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• SOA Summit - Oracle Session Replay

  - by Bruce Tierney

  If you think you missed the most recent Integration Developer News (IDN) "SOA Summit" 2013...good news, you didn't.  At least not the replay of the Oracle session titled: Three Solutionsfor Simplifying Cloud/On-Premises Integration As you will see in the reply below, this session introduces Three common reasons for integration complexity: Disparate Toolkits Lack of API Management Rigid, Brittle Infrastructure and then the Three solutions to these challenges: Unify Cloud On-premises Integration Enable Multi-channel Development with API Management Plan for the Unexpected - Future Readiness The last solution on future readiness describes how you can transition from being reactive to new trends, such as the Internet of Things (IoT), by modifying your integration strategy to enable business agility and how to recognize trends through Fast Data event processing ahead of your competition. Oracle SOA Suite customer SFpark's (San Francisco Metropolitan Transit Authority) implementation with API Management is covered as shown in the screenshot to the right This case study covers the core areas of API Management for partners to build their own applications by leveraging parking availability and real-time pricing as well as mobile enablement of data integrated by SOA Suite underneath.  Download the free SFpark app from the Apple and Android app stores to check it out. When looking into the future, the discussion starts with a historical look to better prepare for what comes next.   As shown in the image below, one of the next frontiers after mobile and cloud integration is a deeper level of direct "enterprise to customer" interaction.  Much of this relates to the Internet of Things.  Examples of IoT from the perspective of SOA and integration is also covered in the session. For example, early adopter Turkcell and their tracking of mobile phone users as they move from point A to B to C is shown in the image the right.   As you look into more "smart services" such as Location-Based Services, how "future ready" is your application infrastructure?  . . . Check out the replay by clicking the video image below to learn about these three challenges and solution including how to "future ready" your application infrastructure:

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