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  • 2D Grid Map Connectivity Check (avoiding stack overflow)

    - by SombreErmine
    I am trying to create a routine in C++ that will run before a more expensive A* algorithm that checks to see if two nodes on a 2D grid map are connected or not. What I need to know is a good way to accomplish this sequentially rather than recursively to avoid overflowing the stack. What I've Done Already I've implemented this with ease using a recursive algorithm; however, depending upon different situations it will generate a stack overflow. Upon researching this, I've come to the conclusion that it is overflowing the stack because of too many recursive function calls. I am sure that my recursion does not enter an infinite loop. I generate connected sets at the beginning of the level, and then I use those connected sets to determine connectivity on the fly later. Basically, the generating algorithm starts from left-to-right top-to-bottom. It skips wall nodes and marks them as visited. Whenever it reaches a walkable node, it recursively checks in all four cardinal directions for connected walkable nodes. Every node that gets checked is marked as visited so they aren't handled twice. After checking a node, it is added to either a walls set, a doors set, or one of multiple walkable nodes sets. Once it fills that area, it continues the original ltr ttb loop skipping already-visited nodes. I've also looked into flood-fill algorithms, but I can't make sense of the sequential algorithms and how to adapt them. Can anyone suggest a better way to accomplish this without causing a stack overflow? The only way I can think of is to do the left-to-right top-to-bottom loop generating connected sets on a row basis. Then check the previous row to see if any of the connected sets are connected and then join the sets that are. I haven't decided on the best data structures to use for that though. I also just thought about having the connected sets pre-generated outside the game, but I wouldn't know where to start with creating a tool for that. Any help is appreciated. Thanks!

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  • Sparse virtual machine disk image resizing weirdness?

    - by Matt H
    I have a partitioned virtual machine disk image created by vmware. What I want to do is resize that by 10GB. The file size is showing as 64424509440. Or 60GB. So I ran this: dd if=/dev/zero of=./win7.img seek=146800640 count=0 It ran without errors and I can verify the new size is in fact 75161927680 bytes or 70GB. This is where it gets a little odd. I started the guest domain in xen which is a Windows 7 enterprise machine. What I was expecting to see in diskmgmt.msc is 2 partitions. 1 system partition at the start of around 100MB and near 60GB partition (which is C drive) followed by around 10GB of free space. Actually what I saw was a 70GB partition!?! That confused me... so I decided to run the Check Disk which when you set it on the C drive it asks you to reboot so it'll run on boot. So I did that and during the boot it ran the checks. It got all the way through stage 3 and didn't show any errors at all. Looked at the partitions in disk manager and now C drive has shrunk back to 60GB and there is no free space. What gives? Ok, I thought I'd try mounting it under Dom0 and examining it with fdisk. This is what I get when mounted sudo xl block-attach 0 tap:aio:/home/xen/vms/otoy_v1202-xen.img xvda w sudo fdisk -l /dev/xvda Disk /dev/xvda: 64.4 GB, 64424509440 bytes 255 heads, 63 sectors/track, 7832 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x582dfc96 Device Boot Start End Blocks Id System /dev/xvda1 * 1 13 102400 7 HPFS/NTFS Partition 1 does not end on cylinder boundary. /dev/xvda2 13 7833 62810112 7 HPFS/NTFS Note the cylinder boundary comment. When I run sudo cfdisk /dev/xvda I get: FATAL ERROR: Bad primary partition 1: Partition ends in the final partial cylinder Press any key to exit cfdisk So I guess this is a bigger problem than first thought. How can I fix this? EDIT: Oops, the cylinder boundary thing is not a problem at all since disks have used LBA etc. So that threw me for a moment... still the problem exists... Now this output looks a little different. sudo sfdisk -uS -l /dev/xvda Disk /dev/xvda: 7832 cylinders, 255 heads, 63 sectors/track Units = sectors of 512 bytes, counting from 0 Device Boot Start End #sectors Id System /dev/xvda1 * 2048 206847 204800 7 HPFS/NTFS /dev/xvda2 206848 125827071 125620224 7 HPFS/NTFS /dev/xvda3 0 - 0 0 Empty /dev/xvda4 0 - 0 0 Empty BTW: I do have a backup of the image so if you help me mess it up that's ok. EDIT: sudo parted /dev/xvda print free Model: Xen Virtual Block Device (xvd) Disk /dev/xvda: 64.4GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 32.3kB 1049kB 1016kB Free Space 1 1049kB 106MB 105MB primary ntfs boot 2 106MB 64.4GB 64.3GB primary ntfs 64.4GB 64.4GB 1049kB Free Space Cool. Linux is showing free space is 10GB which is what I expect. The problem is windows isn't seeing this?

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  • CMS vs Admin Panel?

    - by Bob
    Okay, so this probably seems like an unusual, more grammar related question, but I was unsure of what to call it. If you use a software such as vBulletin or MyBB or even Blogger and you're the administrator (or other, lesser position such as moderator) of the forum, or publisher/author of the blog, you generally have access to something of an "admin panel". For example, vBulletin's admin panel looks like this and Blogger's admin panel looks something like this. While they both look different and do different things, the goal is fundamentally the same: to provide the user with a method for adding, modifying, or deleting content... to let them control and administrate their forum or blog. Also, they're both made specifically by the company for use in a specific product. Now, there's also options like Drupal. It seems to offer quite a bit more and be quite a bit more generalized. How does something like this work? If you were freelancing, would you deploy a website with Drupal, or would it be something the client might already have installed on their own server? I've never really used Drupal, only heard about it, so please let me know. Also, there seems to be other options like cPanel, a sort of global CMS that allows you to administrate over your entire website. How do those work in comparison to Drupal, or the administrative panels with vBulletin? They seem to serve related, but different purposes. Basically, what is the norm? If I'm developing a web application for a group that needs to be able to edit their website without the need to go into the code or the database (or rather, wants to act in a graphical, easy-to-use content-management/admin panel), would it also be necessary to write my own miniature admin panel? Or would I be able to send them off knowing that they have cPanel? Or could something like Drupal fill this void? Again, I'm a little new to web development, and I'm working on planning out my first, real, large website. So I need a little advice on the standards and expectations for web development - security and coding practices aside, what should I be looking for as far as usability and administration for the client (who will be running the site once I'm done creating the website)? Any extra tips would also be appreciated! Oh, and just a little bit: I'm writing the website using Ruby on the Sinatra framework (both Ruby and Sinatra are things I'm fairly comfortable with) and I'm not being paid to make the website (and I will also be a user, and one of the three administrators of the website) - it's being built for a club I'm in.

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  • Don't Forget To Enjoy Life

    - by Justin
    I have a pretty clear stance on posting personal information in my blogs. I tend to avoid it almost instinctively. Part of that is because I am a somewhat private person. And the other is because I know how easy it is for personal information to be gathered and collected from sources such as blogs. So, this has remained a tech only blog for me. I've only posted topics mostly related to issues I have encountered at work. In a way this blog is a 'bookmark' for me. If I post something here and run into the issue again it allows me to refer back to a convenient place where the 'fix' is documented in a way that I understand. But today, I am posting something that speaks to everyone. Something PERSONAL. Honestly, I expect this entry to receive zero views. But if nothing else, I can come back to this blog one day when I'm having a bad day or something and run across this post. And I will be reminded... DON'T FORGET TO ENJOY LIFE. Say this to yourself out loud, right now. People, we can get caught up in some rather mundane details as we trek through life. It's so easy to lose track of what really matters that it should be no surprise to find yourself reading something like this and thinking to yourself 'Yeah. You are right, man. Some of this crap I'm clinging on to right now is so small in the grand scheme of things'. I have no reservation, no shame, in saying that I am more often than not caught up in the ever evolving world of 'shit that does not matter'. When you work in technology, you are surrounded by deadlines, upgrades, new versions, support 'end of life', etc. And by time you get done with your 8 hours you go home and put in a few more because you are STILL CAUGHT UP in the things you dealt with at work all day. DO YOURSELF A FAVOR. DO YOUR FAMILY AND FRIEND A FAVOR. When you are done for the day, and you drive home, get those work-related things out of your head before you pull into the driveway. If you are still thinking on them when you park the car, leave the engine running, close your eyes and take a deep breath. If you believe in God, pray. If you don't then meditate for a second with the INTENTION of letting go of the day and becoming the 'real you'. You may have forgotten who the real you is so I'll remind you.... THE REAL YOU IS THAT GUY OR GAL THAT LAUGHS, LOVES, AND LIVES. Be the real you as often as possible. If you can't do it during your 9 - 5, do it at home. YOUR RELATIONSHIPS AND YOUR PERSONAL HAPPINESS DEPEND ON IT. I am going to make you a promise right now. If you do what I've just said, your days will be longer and your joy will be exponential. I can't explain why I know this to be true. But I do know it. And if you are there reading this right now, you know it is true too. We both know it is true because it COMES FROM WITHIN EVERY MAN, WOMAN and CHILD. We are born into love and happiness. Lets not fade away into the darkness so easily found in this world. Lets keep the flame burning. The flame of passion. Passion for LIFE. Peace be with you.

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  • How views are changing in future versions of SQL

    - by Rob Farley
    April is here, and this weekend, SQL v11.0 (previous known as Denali, now known as SQL Server 2012) reaches general availability. And so I thought I’d share some news about what’s coming next. I didn’t hear this at the MVP Summit earlier this year (where there was lots of NDA information given, but I didn’t go), so I think I’m free to share it. I’ve written before about CTEs being query-scoped views. Well, the actual story goes a bit further, and will continue to develop in future versions. A CTE is a like a “temporary temporary view”, scoped to a single query. Due to globally-scoped temporary objects using a two-hashes naming style, and session-scoped (or ‘local’) temporary objects a one-hash naming style, this query-scoped temporary object uses a cunning zero-hash naming style. We see this implied in Books Online in the CREATE TABLE page, but as we know, temporary views are not yet supported in the SQL Server. However, in a breakaway from ANSI-SQL, Microsoft is moving towards consistency with their naming. We know that a CTE is a “common table expression” – this is proving to be a more strategic than you may have appreciated. Within the Microsoft product group, the term “Table Expression” is far more widely used than just CTEs. Anything that can be used in a FROM clause is referred to as a Table Expression, so long as it doesn’t actually store data (which would make it a Table, rather than a Table Expression). You can see this is not just restricted to the product group by doing an internet search for how the term is used without ‘common’. In the past, Books Online has referred to a view as a “virtual table” (but notice that there is no SQL 2012 version of this page). However, it was generally decided that “virtual table” was a poor name because it wasn’t completely accurate, and it’s typically accepted that virtualisation and SQL is frowned upon. That page I linked to says “or stored query”, which is slightly better, but when the SQL 2012 version of that page is actually published, the line will be changed to read: “A view is a stored table expression (STE)”. This change will be the first of many. During the SQL 2012 R2 release, the keyword VIEW will become deprecated (this will be SQL v11 SP1.5). Three versions later, in SQL 14.5, you will need to be in compatibility mode 140 to allow “CREATE VIEW” to work. Also consistent with Microsoft’s deprecation policy, the execution of any query that refers to an object created as a view (rather than the new “CREATE STE”), will cause a Deprecation Event to fire. This will all be in preparation for the introduction of Single-Column Table Expressions (to be introduced in SQL 17.3 SP6) which will finally shut up those people waiting for a decent implementation of Inline Scalar Functions. And of course, CTEs are “Common” because the Table Expression definition needs to be repeated over and over throughout a stored procedure. ...or so I think I heard at some point. Oh, and congratulations to all the new MVPs on this April 1st. @rob_farley

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  • Mouse Clicks, Reactive Extensions and StreamInsight Mashup

    I had an hour spare this afternoon so I wanted to have another play with Reactive Extensions in .Net and StreamInsight.  I also didn’t want to simply use a console window as a way of gathering events so I decided to use a windows form instead. The task I set myself was this. Whenever I click on my form I want to subscribe to the event and output its location to the console window and also the timestamp of the event.  In addition to this I want to know for every mouse click I do, how many mouse clicks have happened in the last 5 seconds. The second point here is really interesting.  I have often found this when working with people on problems.  It is how you ask the question that determines how you tackle the problem.  I will show 2 ways of possibly answering the second question depending on how the question was interpreted. As a side effect of this example I will show how time in StreamInsight can stand still.  This is an important concept and we can see it in the output later. Now to the code.  I will break it all down in this blogpost but you can download the solution and see it all together. I created a Console application and then instantiate a windows form.   frm = new Form(); Thread g = new Thread(CallUI); g.SetApartmentState(ApartmentState.STA); g.Start();   Call UI looks like this   static void CallUI() { System.Windows.Forms.Application.Run(frm); frm.Activate(); frm.BringToFront(); }   Now what we need to do is create an observable from the MouseClick event on the form.  For this we use the Reactive Extensions.   var lblevt = Observable.FromEvent<MouseEventArgs>(frm, "MouseClick").Timestamp();   As mentioned earlier I have two objectives in this example and to solve the first I am going to again use the Reactive extensions.  Let’s subscribe to the MouseClick event and output the location and timestamp to the console. lblevt.Subscribe(evt => { Console.WriteLine("Clicked: {0}, {1} ", evt.Value.EventArgs.Location,evt.Timestamp); }); That should take care of obective #1 but what about the second objective.  For that we need some temporal windowing and this means StreamInsight.  First we need to turn our Observable collection of MouseClick events into a PointStream Server s = Server.Create("Default"); Microsoft.ComplexEventProcessing.Application a = s.CreateApplication("MouseClicks"); var input = lblevt.ToPointStream( a, evt => PointEvent.CreateInsert( evt.Timestamp, new { loc = evt.Value.EventArgs.Location.ToString(), ts = evt.Timestamp.ToLocalTime().ToString() }), AdvanceTimeSettings.IncreasingStartTime);   Now that we have created out PointStream we need to do something with it and this is where we get to our second objective.  It is pretty clear that we want some kind of windowing but what? Here is one way of doing it.  It might not be what you wanted but again it is how the second objective is interpreted   var q = from i in input.TumblingWindow(TimeSpan.FromSeconds(5), HoppingWindowOutputPolicy.ClipToWindowEnd) select new { CountOfClicks = i.Count() };   The above code creates tumbling windows of 5 seconds and counts the number of events in the windows.  If there are no events in the window then no result is output.  Likewise until an event (MouseClick) is issued then we do not see anything in the output (that is not strictly true because it is the CTI strapped to our MouseClick events that flush the events through the StreamInsight engine not the events themselves).  This approach is centred around the windows and not the events.  Until the windows complete and a CTI is issued then no events are pushed through. An alternate way of answering our second question is below   var q = from i in input.AlterEventDuration(evt => TimeSpan.FromSeconds(5)).SnapshotWindow(SnapshotWindowOutputPolicy.Clip) select new { CountOfClicks = i.Count() };   In this code we extend the duration of each MouseClick to five seconds.  We then create  Snapshot Windows over those events.  Snapshot windows are discussed in detail here.  With this solution we are centred around the events.  It is the events that are driving the output.  Let’s have a look at the output from this solution as it may be a little confusing. First though let me show how we get the output from StreamInsight into the Console window. foreach (var x in q.ToPointEnumerable().Where(e => e.EventKind != EventKind.Cti)) { Console.WriteLine(x.Payload.CountOfClicks); }   Ok so now to the output.   The table at the top shows the output from our routine and the table at the bottom helps to explain the output.  One of the things that will help as well is, you will note that for our PointStream we set the issuing of CTIs to be IncreasingStartTime.  What this means is that the CTI is placed right at the start of the event so will not flush the event with which it was issued but will flush those prior to it.  In the bottom table the Blue fill is where we issued a click.  Yellow fill is the duration and boundaries of our events.  The numbers at the bottom indicate the count of events   Clicked 22:40:16                                 Clicked 23:40:18                                 1                                   Clicked 23:40:20                                 2                                   Clicked 23:40:22                                 3                                   2                                   Clicked 23:40:24                                 3                                   2                                   Clicked 23:40:32                                 3                                   2                                   1                                                                                                         secs 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32                                                                                                                                                                                                                         counts   1   2 3 2 3 2 3   2   1           What we can see here in the output is that the counts include all the end edges that have occurred between the mouse clicks.  If we look specifically at the mouse click at 22:40:32. then we see that 3 events are returned to us. These include the following End Edge count at 22:40:25 End Edge count at 22:40:27 End Edge count at 22:40:29 Another thing we notice is that until we actually issue a CTI at 22:40:32 then those last 3 snapshot window counts will never be reported. Hopefully this has helped to explain  a few concepts around StreamInsight and the IObservable() pattern.   You can download this solution from here and play.  You will need the Reactive Framework from here and StreamInsight 1.1

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  • JavaOne User Group Sunday

    - by Tori Wieldt
    Before any "official" sessions of JavaOne 2012, the Java community was already sizzling. User Group Sunday was a great success, with several sessions offered by Java community members for anyone wanting to attend. Sessions were both about Java and best practices for running a JUG. Technical sessions included "Autoscaling Web Java Applications: Handle Peak Traffic with Zero Downtime and Minimized Cost,"  "Using Java with HTML5 and CSS3," and "Gooey and Sticky Bits: Everything You Ever Wanted to Know About Java." Several sessions were about how to start and run a JUG, like "Getting Speakers, Finding Sponsors, Planning Events: A Day in the Life of a JUG" and "JCP and OpenJDK: Using the JUGs’ “Adopt” Programs in Your Group." Badr ElHouari and Faiçal Boutaounte presented the session "Why Communities Are Important and How to Start One." They used the example of the Morocco JUG, which they started. Before the JUG, there was no "Java community," they explained. They shared their best practices, including: have fun, enjoy what you are doing get a free venue to have regular meetings, a University is a good choice run a conference, it gives you visibility and brings in new members students are a great way to grow a JUG Badr was proud to mention JMaghreb, a first-time conference that the Morocco JUG is hosting in November. They have secured sponsors and international speakers, and are able to offer a free conference for Java developers in North Africa. The session also included a free-flowing discussion about recruiters (OK to come to meetings, but not to dominate them), giving out email addresses (NEVER do without permission), no-show rates (50% for free events) and the importance of good content (good speakers really help!). Trisha Gee, member of the London Java Community (LJC) was one of the presenters for the session "Benefits of Open Source." She explained how open sourcing the LMAX Disruptor (a high performance inter-thread messaging library) gave her company LMAX several benefits, including more users, more really good quality new hires, and more access to 3rd party companies. Being open source raised the visibility of the company and the product, which was good in many ways. "We hired six really good coders in three months," Gee said. They also got community contributors for their code and more cred with technologists. "We had been unsuccessful at getting access to executives from other companies in the high-performance space. But once we were open source, the techies at the company had heard of us, knew our code was good, and that opened lots of doors for us." So, instead of "giving away the secret sauce," by going open source, LMAX gained many benefits. "It was a great day," said Bruno Souza, AKA The Brazilian Java Man, "the sessions were well attended and there was lots of good interaction." Sizzle and steak!

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  • Why Is Hibernation Still Used?

    - by Jason Fitzpatrick
    With the increased prevalence of fast solid-state hard drives, why do we still have system hibernation? Today’s Question & Answer session comes to us courtesy of SuperUser—a subdivision of Stack Exchange, a community-driven grouping of Q&A web sites. The Question SuperUser reader Moses wants to know why he should use hibernate on a desktop machine: I’ve never quite understood the original purpose of the Hibernation power state in Windows. I understand how it works, what processes take place, and what happens when you boot back up from Hibernate, but I’ve never truly understood why it’s used. With today’s technology, most notably with SSDs, RAM and CPUs becoming faster and faster, a cold boot on a clean/efficient Windows installation can be pretty fast (for some people, mere seconds from pushing the power button). Standby is even faster, sometimes instantaneous. Even SATA drives from 5-6 years ago can accomplish these fast boot times. Hibernation seems pointless to me [on desktop computers] when modern technology is considered, but perhaps there are applications that I’m not considering. What was the original purpose behind hibernation, and why do people still use it? Quite a few people use hibernate, so what is Moses missing in the big picture? The Answer SuperUser contributor Vignesh4304 writes: Normally hibernate mode saves your computer’s memory, this includes for example open documents and running applications, to your hard disk and shuts down the computer, it uses zero power. Once the computer is powered back on, it will resume everything where you left off. You can use this mode if you won’t be using the laptop/desktop for an extended period of time, and you don’t want to close your documents. Simple Usage And Purpose: Save electric power and resuming of documents. In simple terms this comment serves nice e.g (i.e. you will sleep but your memories are still present). Why it’s used: Let me describe one sample scenario. Imagine your battery is low on power in your laptop, and you are working on important projects on your machine. You can switch to hibernate mode – it will result your documents being saved, and when you power on, the actual state of application gets restored. Its main usage is like an emergency shutdown with an auto-resume of your documents. MagicAndre1981 highlights the reason we use hibernate everyday: Because it saves the status of all running programs. I leave all my programs open and can resume working the next day very easily. Doing a real boot would require to start all programs again, load all the same files into those programs, get to the same place that I was at before, and put all my windows in exactly the same place. Hibernating saves a lot of work pulling these things back up again. It’s not unusual to find computers around the office here that have been hibernated day in and day out for months without an actual full system shutdown and restart. It’s enormously convenient to freeze your work space at the exact moment you stopped working and to turn right around and resume there the next morning. Have something to add to the explanation? Sound off in the the comments. Want to read more answers from other tech-savvy Stack Exchange users? Check out the full discussion thread here.     

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  • Oracle GoldenGate 11g Release 2 Launch Webcast Replay Available

    - by Irem Radzik
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman","serif"; mso-fareast-font-family:"Times New Roman";} For those of you who missed Oracle GoldenGate 11g Release 2 launch webcasts last week, the replay is now available from the following url. Harnessing the Power of the New Release of Oracle GoldenGate 11g I would highly recommend watching the webcast to meet many new features of the new release and hear the product management team respond to the questions from the audience in a nice long Q&A section. In my blog last week I listed the media coverage for this new release. There is a new article published by ITJungle talking about Oracle GoldenGate’s heterogeneity and support for DB2 for iSeries: Oracle Completes DB2/400 Support in Data Replication Tool As mentioned in last week’s blog, we received over 150 questions from the audience and in this blog I'd like to continue to post some of the frequently asked,  questions and their answers: Question: What are the fundamental differences between classic data capture and integrated data capture? Do both use the redo logs in the source database? Answer: Yes, they both use redo logs. Classic capture parses the redo log data directly, whereas the Integrated Capture lets the Oracle database parse the redo log record using an internal API. Question: Does GoldenGate version need to match Oracle Database version? Answer: No, they are not directly linked. Oracle GoldenGate 11g Release 2 supports Oracle Database version 10gR2 as well. For Oracle Database version 10gR1 and Oracle Database version 9i you will need GoldenGate11g Release 1 or lower. And for Oracle Database 8i you need Oracle GoldenGate 10 or earlier versions. Question: If I already use Data Guard, do I need GoldenGate? Answer: Data Guard is designed as the best disaster recovery solution for Oracle Database. If you would like to implement a bidirectional Active-Active replication solution or need to move data between heterogeneous systems, you will need GoldenGate. Question: On Compression and GoldenGate, if the source uses compression, is it required that the target also use compression? Answer: No, the source and target do not need to have the same compression settings. Question: Does GG support Advance Security Option on the Source database? Answer: Yes it does. Question: Can I use GoldenGate to upgrade the Oracle Database to 11g and do OS migration at the same time? Answer: Yes, this is a very common project where GoldenGate can eliminate downtime, give flexibility to test the target as needed, and minimize risks with fail-back option to the old environment. For more information on database upgrades please check out the following white papers: Best Practices for Migrating/Upgrading Oracle Database Using Oracle GoldenGate 11g Zero-Downtime Database Upgrades Using Oracle GoldenGate Question: Does GoldenGate create any trigger in the source database table level or row level to for real-time data integration? Answer: No, GoldenGate does not create triggers. Question: Can transformation be done after insert to destination table or need to be done before? Answer: It can happen in the Capture (Extract) process, in the  Delivery (Replicat) process, or in the target database. For more resources on Oracle GoldenGate 11gR2 please check out our Oracle GoldenGate 11gR2 resource kit as well.

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  • Cloud hosted CI for .NET projects

    - by Scott Dorman
    Originally posted on: http://geekswithblogs.net/sdorman/archive/2014/06/02/cloud-hosted-ci-for-.net-projects.aspxContinuous integration (CI) is important. If you don’t have it set up…you should. There are a lot of different options available for hosting your own CI server, but they all require you to maintain your own infrastructure. If you’re a business, that generally isn’t a problem. However, if you have some open source projects hosted, for example on GitHub, there haven’t really been any options. That has changed with the latest release of AppVeyor, which bills itself as “Continuous integration for busy developers.” What’s different about AppVeyor is that it’s a hosted solution. Why is that important? By being a hosted solution, it means that I don’t have to maintain my own infrastructure for a build server. How does that help if you’re hosting an open source project? AppVeyor has a really competitive pricing plan. For an unlimited amount of public repositories, it’s free. That gives you a cloud hosted CI system for all of your GitHub projects for the cost of some time to set them up, which actually isn’t hard to do at all. I have several open source projects (hosted at https://github.com/scottdorman), so I signed up using my GitHub credentials. AppVeyor fully supported my two-factor authentication with GitHub, so I never once had to enter my password for GitHub into AppVeyor. Once it was done, I authorized GitHub and it instantly found all of the repositories I have (both the ones I created and the ones I cloned from elsewhere). You can even add “build badges” to your markdown files in GitHub, so anyone who visits your project can see the status of the lasted build. Out of the box, you can simply select a repository, add the build project, click New Build and wait for the build to complete. You now have a complete CI server running for your project. The best part of this, besides the fact that it “just worked” with almost zero configuration is that you can configure it through a web-based interface which is very streamlined, clean and easy to use or you can use a appveyor.yml file. This means that you can define your CI build process (including any scripts that might need to be run, etc.) in a standard file format (the YAML format) and store it in your repository. The benefits to that are huge. The file becomes a versioned artifact in your source control system, so it can be branched, merged, and is completely transparent to anyone working on the project. By the way, AppVeyor isn’t limited to just GitHub. It currently supports GitHub, BitBucket, Visual Studio Online, and Kiln. I did have a few issues getting one of my projects to build, but the same day I posted the problem to the support forum a fix was deployed, and I had a functioning CI build about 5 minutes after that. Since then, I’ve provided some additional feature requests and had a few other questions, all of which have seen responses within a 24-hour period. I have to say that it’s easily been one of the best customer support experiences I’ve seen in a long time. AppVeyor is still young, so it doesn’t yet have full feature parity with some of the older (more established) CI systems available,  but it’s getting better all the time and I have no doubt that it will quickly catch up to those other CI systems and then pass them. The bottom line, if you’re looking for a good cloud-hosted CI system for your .NET-based projects, look at AppVeyor.

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  • The Future of Air Travel: Intelligence and Automation

    - by BobEvans
    Remember those white-knuckle flights through stormy weather where unexpected plunges in altitude result in near-permanent relocations of major internal organs? Perhaps there’s a better way, according to a recent Wall Street Journal article: “Pilots of a Honeywell International Inc. test plane stayed on their initial flight path, relying on the company's latest onboard radar technology to steer through the worst of the weather. The specially outfitted Boeing 757 barely shuddered as it gingerly skirted some of the most ferocious storm cells over Fort Walton Beach and then climbed above the rest in zero visibility.” Or how about the multifaceted check-in process, which might not wreak havoc on liver location but nevertheless makes you wonder if you’ve been trapped in some sort of covert psychological-stress test? Another WSJ article, called “The Self-Service Airport,” says there’s reason for hope there as well: “Airlines are laying the groundwork for the next big step in the airport experience: a trip from the curb to the plane without interacting with a single airline employee. At the airport of the near future, ‘your first interaction could be with a flight attendant,’ said Ben Minicucci, chief operating officer of Alaska Airlines, a unit of Alaska Air Group Inc.” And in the topsy-turvy world of air travel, it’s not just the passengers who’ve been experiencing bumpy rides: the airlines themselves are grappling with a range of challenges—some beyond their control, some not—that make profitability increasingly elusive in spite of heavy demand for their services. A recent piece in The Economist illustrates one of the mega-challenges confronting the airline industry via a striking set of contrasting and very large numbers: while the airlines pay $7 billion per year to third-party computerized reservation services, the airlines themselves earn a collective profit of only $3 billion per year. In that context, the anecdotes above point unmistakably to the future that airlines must pursue if they hope to be able to manage some of the factors outside of their control (e.g., weather) as well as all of those within their control (operating expenses, end-to-end visibility, safety, load optimization, etc.): more intelligence, more automation, more interconnectedness, and more real-time awareness of every facet of their operations. Those moves will benefit both passengers and the air carriers, says the WSJ piece on The Self-Service Airport: “Airlines say the advanced technology will quicken the airport experience for seasoned travelers—shaving a minute or two from the checked-baggage process alone—while freeing airline employees to focus on fliers with questions. ‘It's more about throughput with the resources you have than getting rid of humans,’ said Andrew O'Connor, director of airport solutions at Geneva-based airline IT provider SITA.” Oracle’s attempting to help airlines gain control over these challenges by blending together a range of its technologies into a solution called the Oracle Airline Data Model, which suggests the following steps: • To retain and grow their customer base, airlines need to focus on the customer experience. • To personalize and differentiate the customer experience, airlines need to effectively manage their passenger data. • The Oracle Airline Data Model can help airlines jump-start their customer-experience initiatives by consolidating passenger data into a customer data hub that drives realtime business intelligence and strategic customer insight. • Oracle’s Airline Data Model brings together multiple types of data that can jumpstart your data-warehousing project with rich out-of-the-box functionality. • Oracle’s Intelligent Warehouse for Airlines brings together the powerful capabilities of Oracle Exadata and the Oracle Airline Data Model to give you real-time strategic insights into passenger demand, revenues, sales channels and your flight network. The airline industry aside, the bullet points above offer a broad strategic outline for just about any industry because the customer experience is becoming pre-eminent in each and there is simply no way to deliver world-class customer experiences unless a company can capture, manage, and analyze all of the relevant data in real-time. I’ll leave you with two thoughts from the WSJ article about the new in-flight radar system from Honeywell: first, studies show that a single episode of serious turbulence can wrack up $150,000 in additional costs for an airline—so, it certainly behooves the carriers to gain the intelligence to avoid turbulence as much as possible. And second, it’s back to that top-priority customer-experience thing and the value that ever-increasing levels of intelligence can deliver. As the article says: “In the cabin, reporters watched screens showing the most intense parts of the nearly 10-mile wide storm, which churned some 7,000 feet below, in vibrant red and other colors. The screens also were filled with tiny symbols depicting likely locations of lightning and hail, which can damage planes and wreak havoc on the nerves of white-knuckle flyers.”  (Bob Evans is senior vice-president, communications, for Oracle.)  

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  • An invitation to join a JDeveloper and ADF productivity clinic (and more!) at KScope

    - by Chris Muir
    Would you like a chance to influence Oracle's decisions on tool usability and productivity? If you're attending ODTUG's Kaleidoscope conference this year in San Antonio, Oracle would like to invite you to participate in our Usability Activity Research and separately our JDeveloper and ADF Productivity Clinics with our experienced user experience teams.  The teams are keen to hear what you have to say about your experiences with our tools in general and specifically JDeveloper and ADF.  The details of each event are described below. Invitation to Usability Activity - Sunday June 24th to Wednesday June 27th Oracle is constantly working on new tools and new features for developers, and invites YOU to become a key part of the process!  As a special addition to Kscope 12, Oracle will be conducting onsite usability research in the Alyssum room, from Sunday June 24 to Wednesday June 27. Usability activities are scheduled ahead of time for participants' convenience.  If you would like to take part, please fill out this form to let us know of the session(s) that you would like to attend and your development experience. You will be emailed with your scheduled session before the start of the conference. JDeveloper and ADF Productivity Clinic - Thursday June 28th Are you concerned that Java, Oracle ADF or JDeveloper is difficult? Is JDeveloper making you jump through hoops?  Do you hate a particular dialog or feature of JDeveloper? Well, come and get things off your chest! Oracle is hosting a product management and user experience clinic where we want to hear about your issues and concerns. What's difficult to use?  What doesn't work the way you want, and how would you want it to work?  What isn't behaving like your current favorite tool?  If we can't help on you the spot, we'll take your feedback and use it to improve the product experience.  A great opportunity to get answers, or get improvements. Drop by the Alyssum room, anytime from 8:30 to 10:30 on Thursday, June 28. We look forward to seeing you at KScope soon! 

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  • Observing flow control idle time in TCP

    - by user12820842
    Previously I described how to observe congestion control strategies during transmission, and here I talked about TCP's sliding window approach for handling flow control on the receive side. A neat trick would now be to put the pieces together and ask the following question - how often is TCP transmission blocked by congestion control (send-side flow control) versus a zero-sized send window (which is the receiver saying it cannot process any more data)? So in effect we are asking whether the size of the receive window of the peer or the congestion control strategy may be sub-optimal. The result of such a problem would be that we have TCP data that we could be transmitting but we are not, potentially effecting throughput. So flow control is in effect: when the congestion window is less than or equal to the amount of bytes outstanding on the connection. We can derive this from args[3]-tcps_snxt - args[3]-tcps_suna, i.e. the difference between the next sequence number to send and the lowest unacknowledged sequence number; and when the window in the TCP segment received is advertised as 0 We time from these events until we send new data (i.e. args[4]-tcp_seq = snxt value when window closes. Here's the script: #!/usr/sbin/dtrace -s #pragma D option quiet tcp:::send / (args[3]-tcps_snxt - args[3]-tcps_suna) = args[3]-tcps_cwnd / { cwndclosed[args[1]-cs_cid] = timestamp; cwndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); } tcp:::send / cwndclosed[args[1]-cs_cid] && args[4]-tcp_seq = cwndsnxt[args[1]-cs_cid] / { @meantimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = avg(timestamp - cwndclosed[args[1]-cs_cid]); @stddevtimeclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = stddev(timestamp - cwndclosed[args[1]-cs_cid]); @numclosed["cwnd", args[2]-ip_daddr, args[4]-tcp_dport] = count(); cwndclosed[args[1]-cs_cid] = 0; cwndsnxt[args[1]-cs_cid] = 0; } tcp:::receive / args[4]-tcp_window == 0 && (args[4]-tcp_flags & (TH_SYN|TH_RST|TH_FIN)) == 0 / { swndclosed[args[1]-cs_cid] = timestamp; swndsnxt[args[1]-cs_cid] = args[3]-tcps_snxt; @numclosed["swnd", args[2]-ip_saddr, args[4]-tcp_dport] = count(); } tcp:::send / swndclosed[args[1]-cs_cid] && args[4]-tcp_seq = swndsnxt[args[1]-cs_cid] / { @meantimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = avg(timestamp - swndclosed[args[1]-cs_cid]); @stddevtimeclosed["swnd", args[2]-ip_daddr, args[4]-tcp_sport] = stddev(timestamp - swndclosed[args[1]-cs_cid]); swndclosed[args[1]-cs_cid] = 0; swndsnxt[args[1]-cs_cid] = 0; } END { printf("%-6s %-20s %-8s %-25s %-8s %-8s\n", "Window", "Remote host", "Port", "TCP Avg WndClosed(ns)", "StdDev", "Num"); printa("%-6s %-20s %-8d %@-25d %@-8d %@-8d\n", @meantimeclosed, @stddevtimeclosed, @numclosed); } So this script will show us whether the peer's receive window size is preventing flow ("swnd" events) or whether congestion control is limiting flow ("cwnd" events). As an example I traced on a server with a large file transfer in progress via a webserver and with an active ssh connection running "find / -depth -print". Here is the output: ^C Window Remote host Port TCP Avg WndClosed(ns) StdDev Num cwnd 10.175.96.92 80 86064329 77311705 125 cwnd 10.175.96.92 22 122068522 151039669 81 So we see in this case, the congestion window closes 125 times for port 80 connections and 81 times for ssh. The average time the window is closed is 0.086sec for port 80 and 0.12sec for port 22. So if you wish to change congestion control algorithm in Oracle Solaris 11, a useful step may be to see if congestion really is an issue on your network. Scripts like the one posted above can help assess this, but it's worth reiterating that if congestion control is occuring, that's not necessarily a problem that needs fixing. Recall that congestion control is about controlling flow to prevent large-scale drops, so looking at congestion events in isolation doesn't tell us the whole story. For example, are we seeing more congestion events with one control algorithm, but more drops/retransmission with another? As always, it's best to start with measures of throughput and latency before arriving at a specific hypothesis such as "my congestion control algorithm is sub-optimal".

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  • How do you update live web sites with code changes?

    - by Aaron Anodide
    I know this is a very basic question. If someone could humor me and tell me how they would handle this, I'd be greatful. I decided to post this because I am about to install SynchToy to remedy the issue below, and I feel a bit unprofessional using a "Toy" but I can't think of a better way. Many times I find when I am in this situation, I am missing some painfully obvious way to do things - this comes from being the only developer in the company. ASP.NET web application developed on my computer at work Solution has 2 projects: Website (files) WebsiteLib (C#/dll) Using a Git repository Deployed on a GoGrid 2008R2 web server Deployment: Make code changes. Push to Git. Remote desktop to server. Pull from Git. Overwrite the live files by dragging/dropping with windows explorer. In Step 5 I delete all the files from the website root.. this can't be a good thing to do. That's why I am about to install SynchToy... UPDATE: THANKS for all the useful responses. I can't pick which one to mark answer - between using a web deployment - it looks like I have several useful suggesitons: Web Project = whole site packaged into a single DLL - downside for me I can't push simple updates - being a lone developer in a company of 50, this remains something that is simpler at times. Pulling straight from SCM into web root of site - i originally didn't do this out of fear that my SCM hidden directory might end up being exposed, but the answers here helped me get over that (although i still don't like having one more thing to worry about forgetting to make sure is still true over time) Using a web farm, and systematically deploying to nodes - this is the ideal solution for zero downtime, which is actually something I care about since the site is essentially a real time revenue source for my company - i might have a hard time convincing them to double the cost of the servers though. -- finally, the re-enforcement of the basic principal that there needs to be a single click deployment for the site OR ELSE THERE SOMETHING WRONG is probably the most useful thing I got out of the answers. UPDATE 2: I thought I come back to this and update with the actual solution that's been in place for many months now and is working perfectly (for my single web server solution). The process I use is: Make code changes Push to Git Remote desktop to server Pull from Git Run the following batch script: cd C:\Users\Administrator %systemroot%\system32\inetsrv\appcmd.exe stop site "/site.name:Default Web Site" robocopy Documents\code\da\1\work\Tree\LendingTreeWebSite1 c:\inetpub\wwwroot /E /XF connectionsconfig Web.config %systemroot%\system32\inetsrv\appcmd.exe start site "/site.name:Default Web Site" As you can see this brings the site down, uses robocopy to intelligently copy the files that have changed then brings the site back up. It typically runs in less than 2 seconds. Since peak traffic on this site is about 2 requests per second, missing 4 requests per site update is acceptable. Sine I've gotten more proficient with Git I've found that the first four steps above being a "manual process" is also acceptable, although I'm sure I could roll the whole thing into a single click if I wanted to. The documentation for AppCmd.exe is here. The documentation for Robocopy is here.

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  • Essbase BSO Data Fragmentation

    - by Ann Donahue
    Essbase BSO Data Fragmentation Data fragmentation naturally occurs in Essbase Block Storage (BSO) databases where there are a lot of end user data updates, incremental data loads, many lock and send, and/or many calculations executed.  If an Essbase database starts to experience performance slow-downs, this is an indication that there may be too much fragmentation.  See Chapter 54 Improving Essbase Performance in the Essbase DBA Guide for more details on measuring and eliminating fragmentation: http://docs.oracle.com/cd/E17236_01/epm.1112/esb_dbag/daprcset.html Fragmentation is likely to occur in the following situations: Read/write databases that users are constantly updating data Databases that execute calculations around the clock Databases that frequently update and recalculate dense members Data loads that are poorly designed Databases that contain a significant number of Dynamic Calc and Store members Databases that use an isolation level of uncommitted access with commit block set to zero There are two types of data block fragmentation Free space tracking, which is measured using the Average Fragmentation Quotient statistic. Block order on disk, which is measured using the Average Cluster Ratio statistic. Average Fragmentation Quotient The Average Fragmentation Quotient ratio measures free space in a given database.  As you update and calculate data, empty spaces occur when a block can no longer fit in its original space and will either append at the end of the file or fit in another empty space that is large enough.  These empty spaces take up space in the .PAG files.  The higher the number the more empty spaces you have, therefore, the bigger the .PAG file and the longer it takes to traverse through the .PAG file to get to a particular record.  An Average Fragmentation Quotient value of 3.174765 means the database is 3% fragmented with free space. Average Cluster Ratio Average Cluster Ratio describes the order the blocks actually exist in the database. An Average Cluster Ratio number of 1 means all the blocks are ordered in the correct sequence in the order of the Outline.  As you load data and calculate data blocks, the sequence can start to be out of order.  This is because when you write to a block it may not be able to place back in the exact same spot in the database that it existed before.  The lower this number the more out of order it becomes and the more it affects performance.  An Average Cluster Ratio value of 1 means no fragmentation.  Any value lower than 1 i.e. 0.01032828 means the data blocks are getting further out of order from the outline order. Eliminating Data Block Fragmentation Both types of data block fragmentation can be removed by doing a dense restructure or export/clear/import of the data.  There are two types of dense restructure: 1. Implicit Restructures Implicit dense restructure happens when outline changes are done using EAS Outline Editor or Dimension Build. Essbase restructures create new .PAG files restructuring the data blocks in the .PAG files. When Essbase restructures the data blocks, it regenerates the index automatically so that index entries point to the new data blocks. Empty blocks are NOT removed with implicit restructures. 2. Explicit Restructures Explicit dense restructure happens when a manual initiation of the database restructure is executed. An explicit dense restructure is a full restructure which comprises of a dense restructure as outlined above plus the removal of empty blocks Empty Blocks vs. Fragmentation The existence of empty blocks is not considered fragmentation.  Empty blocks can be created through calc scripts or formulas.  An empty block will add to an existing database block count and will be included in the block counts of the database properties.  There are no statistics for empty blocks.  The only way to determine if empty blocks exist in an Essbase database is to record your current block count, export the entire database, clear the database then import the exported data.  If the block count decreased, the difference is the number of empty blocks that had existed in the database.

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  • How to interview a natural scientist for a dev position?

    - by Silas
    I already did some interviews for my company, mostly computer scientists for dev positions but also some testers and project managers. Now I have to fill a vacancy in our research group within the R&D department (side note: “research” means that we try to solve problems in our professional domain/market niche using software in research projects together with universities, other companies, research centres and end user organisations. It’s not computer science research; we’re not going to solve the P=NP problem). Now we invited a guy holding an MSc in chemistry (with a lot of physics in his CV, too), who never had any computer science lesson. I already talked with him about half an hour at a local university’s career days and there’s no doubt the guy is smart. Also his marks are excellent and he graduated with distinction. For his BSc he needed to teach himself programming in Mathematica and told me believably that he liked programming a lot. Also he solved some physical chemistry problem that I probably don’t understand using his own software, implemented in Mathematica, for his MSc thesis. It includes a GUI and a notable size of 8,000 LoC. He seems to be very attracted by what we’re doing in our research group and to be honest it’s quite difficult for an SME like us to get good people. I also am very interested in hiring him since he could assist me in writing project proposals, reports, doing presentations and so on. He would probably fit to our team, too. The only question left is: How can I check if he will get the programming skills he needs to do software implementation in our projects since this will be a significant part of the job? Of course I will ask him what it is, that is fascinating him about programming. I’ll also ask how he proceeded to write his natural science software and how he structured it. I’ll ask about how he managed to obtain the skills and information about software development he needed. But is there something more I could ask? Something more concrete perhaps? Should I ask him to explain his Mathematica solution? To be clear: I’m not looking for knowledge in a particular language or technology stack. We’re a .NET shop in product development but I want to have a free choice for our research projects. So I’m interested in the meta-competence being able to learn whatever is actually needed. I hope this question is answerable and not open-ended since I really like to know if there is a default way to check for the ability to get further programming skills on the job. If something is not clear to you please give me some comments and let me improve my question.

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  • Best approach to depth streaming via existing codec

    - by Kevin
    I'm working on a development system (and game) intended for games set mostly in static third-person views. We produce our scenery by CG and photographic techniques. Our background art is rendered off-line by a production-grade renderer. To allow the runtime imagery to properly interact with the background art, I wrote a program to convert from depth output by Mental Ray into a texture, and a pixel shader to draw a quad such that the Z data comes from the texture. This technique is working out very well, but now we've decided that some of the camera angle changes between scenes should be animated. The animation itself is straightforward to produce from our CG models. We intend to encode it to some HD video codec such as H.264. The problem is that in order to maintain our runtime imagery on the screen, the depth buffer will need to be loaded for each video frame. Due to the bandwidth, the video's depth data will need to be compressed efficiently. I've looked into methods for performing temporal compression of depth info and found an interesting research paper here: http://web4.cs.ucl.ac.uk/staff/j.kautz/publications/depth-streaming.pdf The method establishes a mapping between 16-bit depth values and YCbCr values. The mapping is tuned to the properties of existing video codecs in order to maximize precision of the decoded depths after the YCbCr has undergone video compression. It allows an existing, unmodified video codec to be used on the backend. I'm looking at how to pull this off with the least possible work. (This design change was unplanned.) Our game engine itself is native C++, presently for Win32 and DirectX, although we've worked hard to keep platform dependence segregated because we intend other ports. We don't have motion video facilities in the engine yet but will ultimately need that anyway for cinematics. I was planning on using some off-the-shelf motion video solution we can plug into our engine, and haven't chosen one yet. This new added requirement makes selecting one harder since, among other things, we'll now need to bypass colourspace conversion on one of the streams, and also will need to be playing two streams simultaneously in lockstep, on top of in some cases audio on one of them (for the cinematics). I'm also wondering if it's possible (or even useful) to do the conversion from YCbCr to depth in a pixel shader, or if it's better to just do it in CPU and separately load the resulting depth values into a locked tex. The conversion unfortunately does involve branching logic per-pixel. (There are more naive mappings that don't need branching, but they produce inferior results.) It could be reduced to a table lookup but the table would be 32MB. Programming is second-nature to me but I'm not that experienced with pix shaders and have zero knowledge of off-the-shelf video solutions. I'd therefore be interested in advice from others who may have dealt more with depth streaming, pixel shaders, and/or off-the-shelf codecs, regarding how feasible the proposed application is and what off-the-shelf video systems out there would best get along with this usage case.

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  • Caching items in Orchard

    - by Bertrand Le Roy
    Orchard has its own caching API that while built on top of ASP.NET's caching feature adds a couple of interesting twists. In addition to its usual work, the Orchard cache API must transparently separate the cache entries by tenant but beyond that, it does offer a more modern API. Here's for example how I'm using the API in the new version of my Favicon module: _cacheManager.Get( "Vandelay.Favicon.Url", ctx => { ctx.Monitor(_signals.When("Vandelay.Favicon.Changed")); var faviconSettings = ...; return faviconSettings.FaviconUrl; }); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } There is no need for any code to test for the existence of the cache entry or to later fill that entry. Seriously, how many times have you written code like this: var faviconUrl = (string)cache["Vandelay.Favicon.Url"]; if (faviconUrl == null) { faviconUrl = ...; cache.Add("Vandelay.Favicon.Url", faviconUrl, ...); } Orchard's cache API takes that control flow and internalizes it into the API so that you never have to write it again. Notice how even casting the object from the cache is no longer necessary as the type can be inferred from the return type of the Lambda. The Lambda itself is of course only hit when the cache entry is not found. In addition to fetching the object we're looking for, it also sets up the dependencies to monitor. You can monitor anything that implements IVolatileToken. Here, we are monitoring a specific signal ("Vandelay.Favicon.Changed") that can be triggered by other parts of the application like so: _signals.Trigger("Vandelay.Favicon.Changed"); In other words, you don't explicitly expire the cache entry. Instead, something happens that triggers the expiration. Other implementations of IVolatileToken include absolute expiration or monitoring of the files under a virtual path, but you can also come up with your own.

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  • Why does my code dividing a 2D array into chunks fail?

    - by Borog
    I have a 2D-Array representing my world. I want to divide this huge thing into smaller chunks to make collision detection easier. I have a Chunk class that consists only of another 2D Array with a specific width and height and I want to iterate through the world, create new Chunks and add them to a list (or maybe a Map with Coordinates as the key; we'll see about that). world = new World(8192, 1024); Integer[][] chunkArray; for(int a = 0; a < map.getHeight() / Chunk.chunkHeight; a++) { for(int b = 0; b < map.getWidth() / Chunk.chunkWidth; b++) { Chunk chunk = new Chunk(); chunkArray = new Integer[Chunk.chunkWidth][Chunk.chunkHeight]; for(int x = Chunk.chunkHeight*a; x < Chunk.chunkHeight*(a+1); x++) { for(int y = Chunk.chunkWidth*b; y < Chunk.chunkWidth*(b+1); y++) { // Yes, the tileMap actually is [height][width] I'll have // to fix that somewhere down the line -.- chunkArray[y][x] = map.getTileMap()[x*a][y*b]; // TODO:Attach to chunk } } chunkList.add(chunk); } } System.out.println(chunkList.size()); The two outer loops get a new chunk in a specific row and column. I do that by dividing the overall size of the map by the chunkSize. The inner loops then fill a new chunkArray and attach it to the chunk. But somehow my maths is broken here. Let's assume the chunkHeight = chunkWidth = 64. For the first Array I want to start at [0][0] and go until [63][63]. For the next I want to start at [64][64] and go until [127][127] and so on. But I get an out of bounds exception and can't figure out why. Any help appreciated! Actually I think I know where the problem lies: chunkArray[y][x] can't work, because y goes from 0-63 just in the first iteration. Afterwards it goes from 64-127, so sure it is out of bounds. Still no nice solution though :/ EDIT: if(y < Chunk.chunkWidth && x < Chunk.chunkHeight) chunkArray[y][x] = map.getTileMap()[y][x]; This works for the first iteration... now I need to get the commonly accepted formula.

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  • C Minishell Command Expansion Printing Gibberish

    - by Optimus_Pwn
    I'm writing a unix minishell in C, and am at the point where I'm adding command expansion. What I mean by this is that I can nest commands in other commands, for example: $> echo hello $(echo world! ... $(echo and stuff)) hello world! ... and stuff I think I have it working mostly, however it isn't marking the end of the expanded string correctly, for example if I do: $> echo a $(echo b $(echo c)) a b c $> echo d $(echo e) d e c See it prints the c, even though I didn't ask it to. Here is my code: msh.c - http://pastebin.com/sd6DZYwB expand.c - http://pastebin.com/uLqvFGPw I have a more code, but there's a lot of it, and these are the parts that I'm having trouble with at the moment. I'll try to tell you the basic way I'm doing this. Main is in msh.c, here it gets a line of input from either the commandline or a shellfile, and then calls processline (char *line, int outFD, int waitFlag), where line is the line we just got, outFD is the file descriptor of the output file, and waitFlag tells us whether or not we should wait if we fork. When we call this from main we do it like this: processline (buffer, 1, 1); In processline, we allocate a new line: char expanded_line[EXPANDEDLEN]; We then call expand, in expand.c: expand(line, expanded_line, EXPANDEDLEN); In expand, we copy the characters literally from line to expanded_line until we find a $(, which then calls: static int expCmdOutput(char *orig, char *new, int *oldl_ind, int *newl_ind) orig is line, and new is expanded line. oldl_ind and newl_ind are the current positions in the line and expanded line, respectively. Then we pipe, and recursively call processline, passing it the nested command(for example, if we had "echo a $(echo b)", we would pass processline "echo b"). This is where I get confused, each time expand is called, is it allocating a new chunk of memory EXPANDEDLEN long? If so, this is bad because I'll run out of stack room really quickly(in the case of a hugely nested commandline input). In expand I insert a null character at the end of the expanded string, so why is it printing past it? If you guys need any more code, or explanations, just ask. Secondly, I put the code in pastebin because there's a ton of it, and in my experience people don't like it when I fill up several pages with code. Thanks.

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  • HERMES Medical Solutions Helps Save Lives with MySQL

    - by Bertrand Matthelié
    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:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} HERMES Medical Solutions was established in 1976 in Stockholm, Sweden, and is a leading innovator in medical imaging hardware/software products for health care facilities worldwide. HERMES delivers a plethora of different medical imaging solutions to optimize hospital workflow. 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:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Cambria","serif"; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin;} HERMES advanced algorithms make it possible to detect the smallest changes under therapies important and necessary to optimize different therapeutic methods and doses. Challenges Fighting illness & disease requires state-of-the-art imaging modalities and software in order to diagnose accurately, stage disease appropriately and select the best treatment available. Selecting and implementing a new database platform that would deliver the needed performance, reliability, security and flexibility required by the high-end medical solutions offered by HERMES. Solution Decision to migrate from in-house database to an embedded SQL database powering the HERMES products, delivered either as software, integrated hardware and software solutions, or via the cloud in a software-as-a-service configuration. Evaluation of several databases and selection of MySQL based on its high performance, ease of use and integration, and low Total Cost of Ownership. On average, between 4 and 12 Terabytes of data are stored in MySQL databases underpinning the HERMES solutions. The data generated by each medical study is indeed stored during 10 years or more after the treatment was performed. MySQL-based HERMES systems also allow doctors worldwide to conduct new drug research projects leveraging the large amount of medical data collected. Hospitals and other HERMES customers worldwide highly value the “zero administration” capabilities and reliability of MySQL, enabling them to perform medical analysis without any downtime. Relying on MySQL as their embedded database, the HERMES team has been able to increase their focus on further developing their clinical applications. HERMES Medical Solutions could leverage the Oracle Financing payment plan to spread its investment over time and make the MySQL choice even more valuable. “MySQL has proven to be an excellent database choice for us. We offer high-end medical solutions, and MySQL delivers the reliability, security and performance such solutions require.” Jan Bertling, CEO.

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  • 2D Collision in Canvas - Balls Overlapping When Velocity is High

    - by kushsolitary
    I am doing a simple experiment in canvas using Javascript in which some balls will be thrown on the screen with some initial velocity and then they will bounce on colliding with each other or with the walls. I managed to do the collision with walls perfectly but now the problem is with the collision with other balls. I am using the following code for it: //Check collision between two bodies function collides(b1, b2) { //Find the distance between their mid-points var dx = b1.x - b2.x, dy = b1.y - b2.y, dist = Math.round(Math.sqrt(dx*dx + dy*dy)); //Check if it is a collision if(dist <= (b1.r + b2.r)) { //Calculate the angles var angle = Math.atan2(dy, dx), sin = Math.sin(angle), cos = Math.cos(angle); //Calculate the old velocity components var v1x = b1.vx * cos, v2x = b2.vx * cos, v1y = b1.vy * sin, v2y = b2.vy * sin; //Calculate the new velocity components var vel1x = ((b1.m - b2.m) / (b1.m + b2.m)) * v1x + (2 * b2.m / (b1.m + b2.m)) * v2x, vel2x = (2 * b1.m / (b1.m + b2.m)) * v1x + ((b2.m - b1.m) / (b2.m + b1.m)) * v2x, vel1y = v1y, vel2y = v2y; //Set the new velocities b1.vx = vel1x; b2.vx = vel2x; b1.vy = vel1y; b2.vy = vel2y; } } You can see the experiment here. The problem is, some balls overlap each other and stick together while some of them rebound perfectly. I don't know what is causing this issue. Here's my balls object if that matters: function Ball() { //Random Positions this.x = 50 + Math.random() * W; this.y = 50 + Math.random() * H; //Random radii this.r = 15 + Math.random() * 30; this.m = this.r; //Random velocity components this.vx = 1 + Math.random() * 4; this.vy = 1 + Math.random() * 4; //Random shade of grey color this.c = Math.round(Math.random() * 200); this.draw = function() { ctx.beginPath(); ctx.fillStyle = "rgb(" + this.c + ", " + this.c + ", " + this.c + ")"; ctx.arc(this.x, this.y, this.r, 0, Math.PI*2, false); ctx.fill(); ctx.closePath(); } }

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  • My 2011 Professional Development Goals

    - by kerry
    I thought it might be a good idea to post some professional goals for 2011.  Hopefully, I can look at this list at the end of the year and have accomplished most of them. Release an Android app to the marketplace – I figured I would put this first because I have one that I have been working on for a while and it is about ready.  Along with this, I would like to start another one and continue to develop my Android skills. Contribute free software to the community – Again, I have an SMF plugin that will fill this requirement nicely.  Just need to give it some polish and release it.  That’s not all, I would like to add a few more libraries on github, or possibly contribute to an open source project. Regularly attend a user group meetings outside of Java – A great way to meet people and learn new things. Obtain the Oracle Certified Web Developer Certification – I got the SCJP a few years ago and would like to obtain another one.  One step closer to Certified Enterprise Architect. Learn scala – As a language geek, I like to stick to the Pragmatic Programmer’s ‘learn a new language every year’ rule (last year was Ruby).  Scala presents some new concepts all wrapped in a JVM-based OOP language.  Time to dig in. Write an app using JSF – New JEE 6 features are pretty slick.  I want to really leverage them in an app. Present at a user group meeting – Last but not least, I would like to improve my public speaking and skills in presenting.  Also, is a great reason to dig in to some latest and greatest tech. Use git more, and more effectively – Trying to move all my personal projects from Subversion to Git. That’s it.  A little daunting, but I am confident I can at least touch on most of these and it’s a great roadmap to my professional development.

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  • AABB vs OBB Collision Resolution jitter on corners

    - by patt4179
    I've implemented a collision library for a character who is an AABB and am resolving collisions between AABB vs AABB and AABB vs OBB. I wanted slopes for certain sections, so I've toyed around with using several OBBs to make one, and it's working great except for one glaring issue; The collision resolution on the corner of an OBB makes the player's AABB jitter up and down constantly. I've tried a few things I've thought of, but I just can't wrap my head around what's going on exactly. Here's a video of what's happening as well as my code: Here's the function to get the collision resolution (I'm likely not doing this the right way, so this may be where the issue lies): public Vector2 GetCollisionResolveAmount(RectangleCollisionObject resolvedObject, OrientedRectangleCollisionObject b) { Vector2 overlap = Vector2.Zero; LineSegment edge = GetOrientedRectangleEdge(b, 0); if (!SeparatingAxisForRectangle(edge, resolvedObject)) { LineSegment rEdgeA = new LineSegment(), rEdgeB = new LineSegment(); Range axisRange = new Range(), rEdgeARange = new Range(), rEdgeBRange = new Range(), rProjection = new Range(); Vector2 n = edge.PointA - edge.PointB; rEdgeA.PointA = RectangleCorner(resolvedObject, 0); rEdgeA.PointB = RectangleCorner(resolvedObject, 1); rEdgeB.PointA = RectangleCorner(resolvedObject, 2); rEdgeB.PointB = RectangleCorner(resolvedObject, 3); rEdgeARange = ProjectLineSegment(rEdgeA, n); rEdgeBRange = ProjectLineSegment(rEdgeB, n); rProjection = GetRangeHull(rEdgeARange, rEdgeBRange); axisRange = ProjectLineSegment(edge, n); float axisMid = (axisRange.Maximum + axisRange.Minimum) / 2; float projectionMid = (rProjection.Maximum + rProjection.Minimum) / 2; if (projectionMid > axisMid) { overlap.X = axisRange.Maximum - rProjection.Minimum; } else { overlap.X = rProjection.Maximum - axisRange.Minimum; overlap.X = -overlap.X; } } edge = GetOrientedRectangleEdge(b, 1); if (!SeparatingAxisForRectangle(edge, resolvedObject)) { LineSegment rEdgeA = new LineSegment(), rEdgeB = new LineSegment(); Range axisRange = new Range(), rEdgeARange = new Range(), rEdgeBRange = new Range(), rProjection = new Range(); Vector2 n = edge.PointA - edge.PointB; rEdgeA.PointA = RectangleCorner(resolvedObject, 0); rEdgeA.PointB = RectangleCorner(resolvedObject, 1); rEdgeB.PointA = RectangleCorner(resolvedObject, 2); rEdgeB.PointB = RectangleCorner(resolvedObject, 3); rEdgeARange = ProjectLineSegment(rEdgeA, n); rEdgeBRange = ProjectLineSegment(rEdgeB, n); rProjection = GetRangeHull(rEdgeARange, rEdgeBRange); axisRange = ProjectLineSegment(edge, n); float axisMid = (axisRange.Maximum + axisRange.Minimum) / 2; float projectionMid = (rProjection.Maximum + rProjection.Minimum) / 2; if (projectionMid > axisMid) { overlap.Y = axisRange.Maximum - rProjection.Minimum; overlap.Y = -overlap.Y; } else { overlap.Y = rProjection.Maximum - axisRange.Minimum; } } return overlap; } And here is what I'm doing to resolve it right now: if (collisionDetection.OrientedRectangleAndRectangleCollide(obb, player.PlayerCollision)) { var resolveAmount = collisionDetection.GetCollisionResolveAmount(player.PlayerCollision, obb); if (Math.Abs(resolveAmount.Y) < Math.Abs(resolveAmount.X)) { var roundedAmount = (float)Math.Floor(resolveAmount.Y); player.PlayerCollision._position.Y -= roundedAmount; } else if (Math.Abs(resolveAmount.Y) <= 30.0f) //Catch cases where the player should be able to step over the top of something { var roundedAmount = (float)Math.Floor(resolveAmount.Y); player.PlayerCollision._position.Y -= roundedAmount; } else { var roundedAmount = (float)Math.Floor(resolveAmount.X); player.PlayerCollision._position.X -= roundedAmount; } } Can anyone see what might be the issue here, or has anyone experienced this before that knows a possible solution? I've tried for a few days to figure this out on my own, but I'm just stumped.

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  • concurrency::extent<N> from amp.h

    - by Daniel Moth
    Overview We saw in a previous post how index<N> represents a point in N-dimensional space and in this post we'll see how to define the N-dimensional space itself. With C++ AMP, an N-dimensional space can be specified with the template class extent<N> where you define the size of each dimension. From a look and feel perspective, you'd expect the programmatic interface of a point type and size type to be similar (even though the concepts are different). Indeed, exactly like index<N>, extent<N> is essentially a coordinate vector of N integers ordered from most- to least- significant, BUT each integer represents the size for that dimension (and hence cannot be negative). So, if you read the description of index, you won't be surprised with the below description of extent<N> There is the rank field returning the value of N you passed as the template parameter. You can construct one extent from another (via the copy constructor or the assignment operator), you can construct it by passing an integer array, or via convenience constructor overloads for 1- 2- and 3- dimension extents. Note that the parameterless constructor creates an extent of the specified rank with all bounds initialized to 0. You can access the components of the extent through the subscript operator (passing it an integer). You can perform some arithmetic operations between extent objects through operator overloading, i.e. ==, !=, +=, -=, +, -. There are operator overloads so that you can perform operations between an extent and an integer: -- (pre- and post- decrement), ++ (pre- and post- increment), %=, *=, /=, +=, –= and, finally, there are additional overloads for plus and minus (+,-) between extent<N> and index<N> objects, returning a new extent object as the result. In addition to the usual suspects, extent offers a contains function that tests if an index is within the bounds of the extent (assuming an origin of zero). It also has a size function that returns the total linear size of this extent<N> in units of elements. Example code extent<2> e(3, 4); _ASSERT(e.rank == 2); _ASSERT(e.size() == 3 * 4); e += 3; e[1] += 6; e = e + index<2>(3,-4); _ASSERT(e == extent<2>(9, 9)); _ASSERT( e.contains(index<2>(8, 8))); _ASSERT(!e.contains(index<2>(8, 9))); grid<N> Our upcoming pre-release bits also have a similar type to extent, grid<N>. The way you create a grid is by passing it an extent, e.g. extent<3> e(4,2,6); grid<3> g(e); I am not going to dive deeper into grid, suffice for now to think of grid<N> simply as an alias for the extent<N> object, that you create when you encounter a function that expects a grid object instead of an extent object. Usage The extent class on its own simply defines the size of the N-dimensional space. We'll see in future posts that when you create containers (arrays) and wrappers (array_views) for your data, it is an extent<N> object that you'll need to use to create those (and use an index<N> object to index into them). We'll also see that it is a grid<N> object that you pass to the new parallel_for_each function that I'll cover in the next post. Comments about this post by Daniel Moth welcome at the original blog.

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