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• I Hereby Resolve… (T-SQL Tuesday #14)

  - by smisner

  It’s time for another T-SQL Tuesday, hosted this month by Jen McCown (blog|twitter), on the topic of resolutions. Specifically, “what techie resolutions have you been pondering, and why?” I like that word – pondering – because I ponder a lot. And while there are many things that I do already because of my job, there are many more things that I ponder about doing…if only I had the time. Then I ponder about making time, but then it’s back to work! In 2010, I was moderately more successful in making time for things that I ponder about than I had been in years past, and I hope to continue that trend in 2011. If Jen hadn’t settled on this topic, I could keep my ponderings to myself and no one would ever know the outcome, but she’s egged me on (and everyone else that chooses to participate)! So here goes… For me, having resolve to do something means that I wouldn’t be doing that something as part of my ordinary routine. It takes extra effort to make time for it. It’s not something that I do once and check off a list, but something that I need to commit to over a period of time. So with that in mind, I hereby resolve… To Learn Something New… One of the things I love about my job is that I get to do a lot of things outside of my ordinary routine. It’s a veritable smorgasbord of opportunity! So what more could I possibly add to that list of things to do? Well, the more I learn, the more I realize I have so much more to learn. It would be much easier to remain in ignorant bliss, but I was born to learn. Constantly. (And apparently to teach, too– my father will tell you that as a small child, I had the neighborhood kids gathered together to play school – in the summer. I’m sure they loved that – but they did it!) These are some of things that I want to dedicate some time to learning this year: Spatial data. I have a good understanding of how maps in Reporting Services works, and I can cobble together a simple T-SQL spatial query, but I know I’m only scratching the surface here. Rob Farley (blog|twitter) posted interesting examples of combining maps and PivotViewer, and I think there’s so many more creative possibilities. I’ve always felt that pictures (including charts and maps) really help people get their minds wrapped around data better, and because a lot of data has a geographic aspect to it, I believe developing some expertise here will be beneficial to my work. PivotViewer. Not only is PivotViewer combined with maps a useful way to visualize data, but it’s an interesting way to work with data. If you haven’t seen it yet, check out this interactive demonstration using Netflx OData feed. According to Rob Farley, learning how to work with PivotViewer isn’t trivial. Just the type of challenge I like! Security. You’ve heard of the accidental DBA? Well, I am the accidental security person – is there a word for that role? My eyes used to glaze over when having to study about security, or  when reading anything about it. Then I had a problem long ago that no one could figure out – not even the vendor’s tech support – until I rolled up my sleeves and painstakingly worked through the myriad of potential problems to resolve a very thorny security issue. I learned a lot in the process, and have been able to share what I’ve learned with a lot of people. But I’m not convinced their eyes weren’t glazing over, too. I don’t take it personally – it’s just a very dry topic! So in addition to deepening my understanding about security, I want to find a way to make the subject as it relates to SQL Server and business intelligence more accessible and less boring. Well, there’s actually a lot more that I could put on this list, and a lot more things I have plans to do this coming year, but I run the risk of overcommitting myself. And then I wouldn’t have time… To Have Fun! My name is Stacia and I’m a workaholic. When I love what I do, it’s difficult to separate out the work time from the fun time. But there are some things that I’ve been meaning to do that aren’t related to business intelligence for which I really need to develop some resolve. And they are techie resolutions, too, in a roundabout sort of way! Photography. When my husband and I went on an extended camping trip in 2009 to Yellowstone and the Grand Tetons, I had a nice little digital camera that took decent pictures. But then I saw the gorgeous cameras that other tourists were toting around and decided I needed one too. So I bought a Nikon D90 and have started to learn to use it, but I’m definitely still in the beginning stages. I traveled so much in 2010 and worked on two book projects that I didn’t have a lot of free time to devote to it. I was very inspired by Kimberly Tripp’s (blog|twitter) and Paul Randal’s (blog|twitter) photo-adventure in Alaska, though, and plan to spend some dedicated time with my camera this year. (And hopefully before I move to Alaska – nothing set in stone yet, but we hope to move to a remote location – with Internet access – later this year!) Astronomy. I have this cool telescope, but it suffers the same fate as my camera. I have been gone too much and busy with other things that I haven’t had time to work with it. I’ll figure out how it works, and then so much time passes by that I forget how to use it. I have this crazy idea that I can actually put the camera and the telescope together for astrophotography, but I think I need to start simple by learning how to use each component individually. As long as I’m living in Las Vegas, I know I’ll have clear skies for nighttime viewing, but when we move to Alaska, we’ll be living in a rain forest. I have no idea what my opportunities will be like there – except I know that when the sky is clear, it will be far more amazing than anything I can see in Vegas – even out in the desert - because I’ll be so far away from city light pollution. I’ve been contemplating putting together a blog on these topics as I learn. As many of my fellow bloggers in the SQL Server community know, sometimes the best way to learn something is to sit down and write about it. I’m just stumped by coming up with a clever name for the new blog, which I was thinking about inaugurating with my move to Alaska. Except that I don’t know when that will be exactly, so we’ll just have to wait and see which comes first!

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• How to get SQL Railroad Diagrams from MSDN BNF syntax notation.

  - by Phil Factor

  pre {margin-bottom:.0001pt; font-size:8.0pt; font-family:"Courier New"; margin-left: 0cm; margin-right: 0cm; margin-top: 0cm; } On SQL Server Books-On-Line, in the Transact-SQL Reference (database Engine), every SQL Statement has its syntax represented in  ‘Backus–Naur Form’ notation (BNF)  syntax. For a programmer in a hurry, this should be ideal because It is the only quick way to understand and appreciate all the permutations of the syntax. It is a great feature once you get your eye in. It isn’t the only way to get the information;  You can, of course, reverse-engineer an understanding of the syntax from the examples, but your understanding won’t be complete, and you’ll have wasted time doing it. BNF is a good start in representing the syntax:  Oracle and SQLite go one step further, and have proper railroad diagrams for their syntax, which is a far more accessible way of doing it. There are three problems with the BNF on MSDN. Firstly, it is isn’t a standard version of  BNF, but an ancient fork from EBNF, inherited from Sybase. Secondly, it is excruciatingly difficult to understand, and thirdly it has a number of syntactic and semantic errors. The page describing DML triggers, for example, currently has the absurd BNF error that makes it state that all statements in the body of the trigger must be separated by commas.  There are a few other detail problems too. Here is the offending syntax for a DML trigger, pasted from MSDN. Trigger on an INSERT, UPDATE, or DELETE statement to a table or view (DML Trigger) CREATE TRIGGER [ schema_name . ]trigger_name ON { table | view } [ WITH <dml_trigger_option> [ ,...n ] ] { FOR | AFTER | INSTEAD OF } { [ INSERT ] [ , ] [ UPDATE ] [ , ] [ DELETE ] } [ NOT FOR REPLICATION ] AS { sql_statement [ ; ] [ ,...n ] | EXTERNAL NAME <method specifier [ ; ] > }   <dml_trigger_option> ::=     [ ENCRYPTION ]     [ EXECUTE AS Clause ]   <method_specifier> ::=  This should, of course, be /* Trigger on an INSERT, UPDATE, or DELETE statement to a table or view (DML Trigger) */ CREATE TRIGGER [ schema_name . ]trigger_name ON { table | view } [ WITH <dml_trigger_option> [ ,...n ] ] { FOR | AFTER | INSTEAD OF } { [ INSERT ] [ , ] [ UPDATE ] [ , ] [ DELETE ] } [ NOT FOR REPLICATION ] AS { {sql_statement [ ; ]} [ ...n ] | EXTERNAL NAME <method_specifier> [ ; ] }   <dml_trigger_option> ::=     [ ENCRYPTION ]     [ EXECUTE AS CLAUSE ]   <method_specifier> ::=     assembly_name.class_name.method_name I’d love to tell Microsoft when I spot errors like this so they can correct them but I can’t. Obviously, there is a mechanism on MSDN to get errors corrected by using comments, but that doesn’t work for me (*Error occurred while saving your data.”), and when I report that the comment system doesn’t work to MSDN, I get no reply. I’ve been trying to create railroad diagrams for all the important SQL Server SQL statements, as good as you’d find for Oracle, and have so far published the CREATE TABLE and ALTER TABLE railroad diagrams based on the BNF. Although I’ve been aware of them, I’ve never realised until recently how many errors there are. Then, Colin Daley created a translator for the SQL Server dialect of  BNF which outputs standard EBNF notation used by the W3C. The example MSDN BNF for the trigger would be rendered as … /* Trigger on an INSERT, UPDATE, or DELETE statement to a table or view (DML Trigger) */ create_trigger ::= 'CREATE TRIGGER' ( schema_name '.' ) ? trigger_name 'ON' ( table | view ) ( 'WITH' dml_trigger_option ( ',' dml_trigger_option ) * ) ? ( 'FOR' | 'AFTER' | 'INSTEAD OF' ) ( ( 'INSERT' ) ? ( ',' ) ? ( 'UPDATE' ) ? ( ',' ) ? ( 'DELETE' ) ? ) ( 'NOT FOR REPLICATION' ) ? 'AS' ( ( sql_statement ( ';' ) ? ) + | 'EXTERNAL NAME' method_specifier ( ';' ) ? )   dml_trigger_option ::= ( 'ENCRYPTION' ) ? ( 'EXECUTE AS CLAUSE' ) ?   method_specifier ::= assembly_name '.' class_name '.' method_name Colin’s intention was to allow anyone to paste SQL Server’s BNF notation into his website-based parser, and from this generate classic railroad diagrams via Gunther Rademacher's Railroad Diagram Generator.  Colin's application does this for you: you're not aware that you are moving to a different site.  Because Colin's 'translator' it is a parser, it will pick up syntax errors. Once you’ve fixed the syntax errors, you will get the syntax in the form of a human-readable railroad diagram and, in this form, the semantic mistakes become flamingly obvious. Gunter’s Railroad Diagram Generator is brilliant. To be able, after correcting the MSDN dialect of BNF, to generate a standard EBNF, and from thence to create railroad diagrams for SQL Server’s syntax that are as good as Oracle’s, is a great boon, and many thanks to Colin for the idea. Here is the result of the W3C EBNF from Colin’s application then being run through the Railroad diagram generator. create_trigger: dml_trigger_option: method_specifier:   Now that’s much better, you’ll agree. This is pretty easy to understand, and at this point any error is immediately obvious. This should be seriously useful, and it is to me. However  there is that snag. The BNF is generally incorrect, and you can’t expect the average visitor to mess about with it. The answer is, of course, to correct the BNF on MSDN and maybe even add railroad diagrams for the syntax. Stop giggling! I agree it won’t happen. In the meantime, we need to collaboratively store and publish these corrected syntaxes ourselves as we do them. How? GitHub?  SQL Server Central?  Simple-Talk? What should those of us who use the system  do with our corrected EBNF so that anyone can use them without hassle?

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• MVC 3 AdditionalMetadata Attribute with ViewBag to Render Dynamic UI

  - by Steve Michelotti

  A few months ago I blogged about using Model metadata to render a dynamic UI in MVC 2. The scenario in the post was that we might have a view model where the questions are conditionally displayed and therefore a dynamic UI is needed. To recap the previous post, the solution was to use a custom attribute called [QuestionId] in conjunction with an “ApplicableQuestions” collection to identify whether each question should be displayed. This allowed me to have a view model that looked like this: 1: [UIHint("ScalarQuestion")] 2: [DisplayName("First Name")] 3: [QuestionId("NB0021")] 4: public string FirstName { get; set; } 5: 6: [UIHint("ScalarQuestion")] 7: [DisplayName("Last Name")] 8: [QuestionId("NB0022")] 9: public string LastName { get; set; } 10: 11: [UIHint("ScalarQuestion")] 12: [QuestionId("NB0023")] 13: public int Age { get; set; } 14: 15: public IEnumerable<string> ApplicableQuestions { get; set; } At the same time, I was able to avoid repetitive IF statements for every single question in my view: 1: <%: Html.EditorFor(m => m.FirstName, new { applicableQuestions = Model.ApplicableQuestions })%> 2: <%: Html.EditorFor(m => m.LastName, new { applicableQuestions = Model.ApplicableQuestions })%> 3: <%: Html.EditorFor(m => m.Age, new { applicableQuestions = Model.ApplicableQuestions })%> by creating an Editor Template called “ScalarQuestion” that encapsulated the IF statement: 1: <%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl" %> 2: <%@ Import Namespace="DynamicQuestions.Models" %> 3: <%@ Import Namespace="System.Linq" %> 4: <% 5: var applicableQuestions = this.ViewData["applicableQuestions"] as IEnumerable<string>; 6: var questionAttr = this.ViewData.ModelMetadata.ContainerType.GetProperty(this.ViewData.ModelMetadata.PropertyName).GetCustomAttributes(typeof(QuestionIdAttribute), true) as QuestionIdAttribute[]; 7: string questionId = null; 8: if (questionAttr.Length > 0) 9: { 10: questionId = questionAttr[0].Id; 11: } 12: if (questionId != null && applicableQuestions.Contains(questionId)) { %> 13: <div> 14: <%: Html.Label("") %> 15: <%: Html.TextBox("", this.Model)%> 16: </div> 17: <% } %> You might want to go back and read the full post in order to get the full context. MVC 3 offers a couple of new features that make this scenario more elegant to implement. The first step is to use the new [AdditionalMetadata] attribute which, so far, appears to be an under appreciated new feature of MVC 3. With this attribute, I don’t need my custom [QuestionId] attribute anymore - now I can just write my view model like this: 1: [UIHint("ScalarQuestion")] 2: [DisplayName("First Name")] 3: [AdditionalMetadata("QuestionId", "NB0021")] 4: public string FirstName { get; set; } 5:   6: [UIHint("ScalarQuestion")] 7: [DisplayName("Last Name")] 8: [AdditionalMetadata("QuestionId", "NB0022")] 9: public string LastName { get; set; } 10:   11: [UIHint("ScalarQuestion")] 12: [AdditionalMetadata("QuestionId", "NB0023")] 13: public int Age { get; set; } Thus far, the documentation seems to be pretty sparse on the AdditionalMetadata attribute. It’s buried in the Other New Features section of the MVC 3 home page and, after showing the attribute on a view model property, it just says, “This metadata is made available to any display or editor template when a product view model is rendered. It is up to you to interpret the metadata information.” But what exactly does it look like for me to “interpret the metadata information”? Well, it turns out it makes the view much easier to work with. Here is the re-implemented ScalarQuestion template updated for MVC 3 and Razor: 1: @{ 2: object questionId; 3: ViewData.ModelMetadata.AdditionalValues.TryGetValue("QuestionId", out questionId); 4: if (ViewBag.applicableQuestions.Contains((string)questionId)) { 5: <div> 6: @Html.LabelFor(m => m) 7: @Html.TextBoxFor(m => m) 8: </div> 9: } 10: } So we’ve gone from 17 lines of code (in the MVC 2 version) to about 7-8 lines of code here. The first thing to notice is that in MVC 3 we now have a property called “AdditionalValues” that hangs off of the ModelMetadata property. This is automatically populated by any [AdditionalMetadata] attributes on the property. There is no more need for me to explicitly write Reflection code to GetCustomAttributes() and then check to see if those attributes were present. I can just call TryGetValue() on the dictionary to see if they were present. Secondly, the “applicableQuestions” anonymous type that I passed in from the calling view – in MVC 3 I now have a dynamic ViewBag property where I can just “dot into” the applicableQuestions with a nicer syntax than dictionary square bracket syntax. And there’s no problems calling the Contains() method on this dynamic object because at runtime the DLR has resolved that it is a generic List<string>. At this point you might be saying that, yes the view got much nicer than the MVC 2 version, but my view model got slightly worse.  In the previous version I had a nice [QuestionId] attribute but now, with the [AdditionalMetadata] attribute, I have to type the string “QuestionId” for every single property and hope that I don’t make a typo. Well, the good news is that it’s easy to create your own attributes that can participate in the metadata’s additional values. The key is that the attribute must implement that IMetadataAware interface and populate the AdditionalValues dictionary in the OnMetadataCreated() method: 1: public class QuestionIdAttribute : Attribute, IMetadataAware 2: { 3: public string Id { get; set; } 4:   5: public QuestionIdAttribute(string id) 6: { 7: this.Id = id; 8: } 9:   10: public void OnMetadataCreated(ModelMetadata metadata) 11: { 12: metadata.AdditionalValues["QuestionId"] = this.Id; 13: } 14: } This now allows me to encapuslate my “QuestionId” string in just one place and get back to my original attribute which can be used like this: [QuestionId(“NB0021”)]. The [AdditionalMetadata] attribute is a powerful and under-appreciated new feature of MVC 3. Combined with the dynamic ViewBag property, you can do some really interesting things with your applications with less code and ceremony.

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• Thread placement policies on NUMA systems - update

  - by Dave

  In a prior blog entry I noted that Solaris used a "maximum dispersal" placement policy to assign nascent threads to their initial processors. The general idea is that threads should be placed as far away from each other as possible in the resource topology in order to reduce resource contention between concurrently running threads. This policy assumes that resource contention -- pipelines, memory channel contention, destructive interference in the shared caches, etc -- will likely outweigh (a) any potential communication benefits we might achieve by packing our threads more densely onto a subset of the NUMA nodes, and (b) benefits of NUMA affinity between memory allocated by one thread and accessed by other threads. We want our threads spread widely over the system and not packed together. Conceptually, when placing a new thread, the kernel picks the least loaded node NUMA node (the node with lowest aggregate load average), and then the least loaded core on that node, etc. Furthermore, the kernel places threads onto resources -- sockets, cores, pipelines, etc -- without regard to the thread's process membership. That is, initial placement is process-agnostic. Keep reading, though. This description is incorrect. On Solaris 10 on a SPARC T5440 with 4 x T2+ NUMA nodes, if the system is otherwise unloaded and we launch a process that creates 20 compute-bound concurrent threads, then typically we'll see a perfect balance with 5 threads on each node. We see similar behavior on an 8-node x86 x4800 system, where each node has 8 cores and each core is 2-way hyperthreaded. So far so good; this behavior seems in agreement with the policy I described in the 1st paragraph. I recently tried the same experiment on a 4-node T4-4 running Solaris 11. Both the T5440 and T4-4 are 4-node systems that expose 256 logical thread contexts. To my surprise, all 20 threads were placed onto just one NUMA node while the other 3 nodes remained completely idle. I checked the usual suspects such as processor sets inadvertently left around by colleagues, processors left offline, and power management policies, but the system was configured normally. I then launched multiple concurrent instances of the process, and, interestingly, all the threads from the 1st process landed on one node, all the threads from the 2nd process landed on another node, and so on. This happened even if I interleaved thread creating between the processes, so I was relatively sure the effect didn't related to thread creation time, but rather that placement was a function of process membership. I this point I consulted the Solaris sources and talked with folks in the Solaris group. The new Solaris 11 behavior is intentional. The kernel is no longer using a simple maximum dispersal policy, and thread placement is process membership-aware. Now, even if other nodes are completely unloaded, the kernel will still try to pack new threads onto the home lgroup (socket) of the primordial thread until the load average of that node reaches 50%, after which it will pick the next least loaded node as the process's new favorite node for placement. On the T4-4 we have 64 logical thread contexts (strands) per socket (lgroup), so if we launch 48 concurrent threads we will find 32 placed on one node and 16 on some other node. If we launch 64 threads we'll find 32 and 32. That means we can end up with our threads clustered on a small subset of the nodes in a way that's quite different that what we've seen on Solaris 10. So we have a policy that allows process-aware packing but reverts to spreading threads onto other nodes if a node becomes too saturated. It turns out this policy was enabled in Solaris 10, but certain bugs suppressed the mixed packing/spreading behavior. There are configuration variables in /etc/system that allow us to dial the affinity between nascent threads and their primordial thread up and down: see lgrp_expand_proc_thresh, specifically. In the OpenSolaris source code the key routine is mpo_update_tunables(). This method reads the /etc/system variables and sets up some global variables that will subsequently be used by the dispatcher, which calls lgrp_choose() in lgrp.c to place nascent threads. Lgrp_expand_proc_thresh controls how loaded an lgroup must be before we'll consider homing a process's threads to another lgroup. Tune this value lower to have it spread your process's threads out more. To recap, the 'new' policy is as follows. Threads from the same process are packed onto a subset of the strands of a socket (50% for T-series). Once that socket reaches the 50% threshold the kernel then picks another preferred socket for that process. Threads from unrelated processes are spread across sockets. More precisely, different processes may have different preferred sockets (lgroups). Beware that I've simplified and elided details for the purposes of explication. The truth is in the code. Remarks: It's worth noting that initial thread placement is just that. If there's a gross imbalance between the load on different nodes then the kernel will migrate threads to achieve a better and more even distribution over the set of available nodes. Once a thread runs and gains some affinity for a node, however, it becomes "stickier" under the assumption that the thread has residual cache residency on that node, and that memory allocated by that thread resides on that node given the default "first-touch" page-level NUMA allocation policy. Exactly how the various policies interact and which have precedence under what circumstances could the topic of a future blog entry. The scheduler is work-conserving. The x4800 mentioned above is an interesting system. Each of the 8 sockets houses an Intel 7500-series processor. Each processor has 3 coherent QPI links and the system is arranged as a glueless 8-socket twisted ladder "mobius" topology. Nodes are either 1 or 2 hops distant over the QPI links. As an aside the mapping of logical CPUIDs to physical resources is rather interesting on Solaris/x4800. On SPARC/Solaris the CPUID layout is strictly geographic, with the highest order bits identifying the socket, the next lower bits identifying the core within that socket, following by the pipeline (if present) and finally the logical thread context ("strand") on the core. But on Solaris on the x4800 the CPUID layout is as follows. [6:6] identifies the hyperthread on a core; bits [5:3] identify the socket, or package in Intel terminology; bits [2:0] identify the core within a socket. Such low-level details should be of interest only if you're binding threads -- a bad idea, the kernel typically handles placement best -- or if you're writing NUMA-aware code that's aware of the ambient placement and makes decisions accordingly. Solaris introduced the so-called critical-threads mechanism, which is expressed by putting a thread into the FX scheduling class at priority 60. The critical-threads mechanism applies to placement on cores, not on sockets, however. That is, it's an intra-socket policy, not an inter-socket policy. Solaris 11 introduces the Power Aware Dispatcher (PAD) which packs threads instead of spreading them out in an attempt to be able to keep sockets or cores at lower power levels. Maximum dispersal may be good for performance but is anathema to power management. PAD is off by default, but power management polices constitute yet another confounding factor with respect to scheduling and dispatching. If your threads communicate heavily -- one thread reads cache lines last written by some other thread -- then the new dense packing policy may improve performance by reducing traffic on the coherent interconnect. On the other hand if your threads in your process communicate rarely, then it's possible the new packing policy might result on contention on shared computing resources. Unfortunately there's no simple litmus test that says whether packing or spreading is optimal in a given situation. The answer varies by system load, application, number of threads, and platform hardware characteristics. Currently we don't have the necessary tools and sensoria to decide at runtime, so we're reduced to an empirical approach where we run trials and try to decide on a placement policy. The situation is quite frustrating. Relatedly, it's often hard to determine just the right level of concurrency to optimize throughput. (Understanding constructive vs destructive interference in the shared caches would be a good start. We could augment the lines with a small tag field indicating which strand last installed or accessed a line. Given that, we could augment the CPU with performance counters for misses where a thread evicts a line it installed vs misses where a thread displaces a line installed by some other thread.)

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• .NET to iOS: From WinForms to the iPad

  - by RobertChipperfield

  One of the great things about working at Red Gate is getting to play with new technology - and right now, that means mobile. A few weeks ago, we decided that a little research into the tablet computing arena was due, and purely from a numbers point of view, that suggested the iPad as a good target device. A quick trip to iPhoneDevCon in San Diego later, and Marine and I came back full of ideas, and with some concept of how iOS development was meant to work. Here's how we went from there to the release of Stacks & Heaps, our geeky take on the classic "Snakes & Ladders" game. Step 1: Buy a Mac I've played with many operating systems in my time: from the original BBC Model B, through DOS, Windows, Linux, and others, but I'd so far managed to avoid buying fruit-flavoured computer hardware! If you want to develop for the iPhone, iPad or iPod Touch, that's the first thing that needs to change. If you've not used OS X before, the first thing you'll realise is that everything is different! In the interests of avoiding a flame war in the comments section, I'll only go so far as to say that a lot of my Windows-flavoured muscle memory no longer worked. If you're in the UK, you'll also realise your keyboard is lacking a # key, and that " and @ are the other way around from normal. The wonderful Ukelele keyboard layout editor restores some sanity here, as long as you don't look at the keyboard when you're typing. I couldn't give up the PC entirely, but a handy application called Synergy comes to the rescue - it lets you share a single keyboard and mouse between multiple machines. There's a few limitations: Alt-Tab always seems to go to the Mac, and Windows 7's UAC dialogs require the local mouse for security reasons, but it gets you a long way at least. Step 2: Register as an Apple Developer You can register as an Apple Developer free of charge, and that lets you download XCode and the iOS SDK. You also get the iPhone / iPad emulator, which is handy, since you'll need to be a paid member before you can deploy your apps to a real device. You can either enroll as an individual, or as a company. They both cost the same ($99/year), but there's a few differences between them. If you register as a company, you can add multiple developers to your team (all for the same $99 - not $99 per developer), and you get to use your company name in the App Store. However, you'll need to send off significantly more documentation to Apple, and I suspect the process takes rather longer than for an individual, where they just need to verify some credit card details. Here's a tip: if you're registering as a company, do so as early as possible. The approval process can take a while to complete, so get the application in in plenty of time. Step 3: Learn to love the square brackets! Objective-C is the language of the iPad. C and C++ are also supported, and if you're doing some serious game development, you'll probably spend most of your time in C++ talking OpenGL, but for forms-based apps, you'll be interacting with a lot of the Objective-C SDK. Like shifting from Ctrl-C to Cmd-C, it feels a little odd at first, with the familiar string.format(.) turning into: NSString *myString = [NSString stringWithFormat:@"Hello world, it's %@", [NSDate date]]; Thankfully XCode's auto-complete is normally passable, if not up to Visual Studio's standards, which coupled with a huge amount of content on Stack Overflow means you'll soon get to grips with the API. You'll need to get used to some terminology changes, though; here's an incomplete approximation: Coming from a .NET background, there's some luxuries you no longer have developing Objective C in XCode: Generics! Remember back in .NET 1.1, when all collections were just objects? Yup, we're back there now. ReSharper. Or, more generally, very much refactoring support. The not-many-keystrokes to rename a class, its file, and al references to it in Visual Studio turns into a much more painful experience in XCode. Garbage collection. This is actually rather less of an issue than you might expect: if you follow the rules, the reference counting provided by Objective C gets you a long way without too much pain. Circular references are their usual problematic self, though. Decent exception handling. You do have exceptions, but they're nowhere near as widely used. Generally, if something goes wrong, you get nil (see translation table above) back. Which brings me on to. Calling a method on a nil object isn't a failure - it just returns nil itself! There's many arguments for and against this, but personally I fall into the "stuff should fail as quickly and explicitly as possible" camp. Less specifically, I found that there's more chance of code failing at runtime rather than getting caught at compile-time: using the @selector(.) syntax to pass a method signature isn't (can't be) checked at compile-time, so the first you know about a typo is a crash when you try and call it. The solution to this is of course lots of great testing, both automated and manual, but I still find comfort in provably correct type safety being enforced in addition to testing. Step 4: Submit to the App Store Assuming you want to distribute to more than a handful of devices, you're going to need to submit your app to the Apple App Store. There's a few gotchas in terms of getting builds signed with the right certificates, and you'll be bouncing around between XCode and iTunes Connect a fair bit, but eventually you get everything checked off the to-do list, and are ready to upload your first binary! With some amount of anticipation, I pressed the Upload button in XCode, ready to release our creation into the world, but was instead greeted by an error informing me my XML file was malformed. Uh. A little Googling later, and it turned out that a simple rename from "Stacks&Heaps.app" to "StacksAndHeaps.app" worked around an XML escaping bug, and we were good to go. The next step is to wait for approval (or otherwise). After a couple of weeks of intensive development, this part is agonising. Did we make it? The Apple jury is still out at the moment, but our fingers are firmly crossed! In the meantime, you can see some screenshots and leave us your email address if you'd like us to get in touch when it does go live at the MobileFoo website. Step 5: Profit! Actually, that wasn't the idea here: Stacks & Heaps is free; there's no adverts, and we're not going to sell all your data either. So why did we do it? We wanted to get an idea of what it's like to move from coding for a desktop environment, to something completely different. We don't know whether in a year's time, the iPad will still be the dominant force, or whether Android will have smoothed out some bugs, tweaked the performance, and polished the UI, but I think it's a fairly sure bet that the tablet form factor is here to stay. We want to meet people who are using it, start chatting to them, and find out about some of the pain they're feeling. What better way to do that than do it ourselves, and get to write a cool game in the process?

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• A Good Developer is So Hard to Find

  - by James Michael Hare

  Let me start out by saying I want to damn the writers of the Toughest Developer Puzzle Ever – 2. It is eating every last shred of my free time! But as I've been churning through each puzzle and marvelling at the brain teasers and trivia within, I began to think about interviewing developers and why it seems to be so hard to find good ones.  The problem is, it seems like no matter how hard we try to find the perfect way to separate the chaff from the wheat, inevitably someone will get hired who falls far short of expectations or someone will get passed over for missing a piece of trivia or a tricky brain teaser that could have been an excellent team member.   In shops that are primarily software-producing businesses or other heavily IT-oriented businesses (Microsoft, Amazon, etc) there often exists a much tighter bond between HR and the hiring development staff because development is their life-blood. Unfortunately, many of us work in places where IT is viewed as a cost or just a means to an end. In these shops, too often, HR and development staff may work against each other due to differences in opinion as to what a good developer is or what one is worth.  It seems that if you ask two different people what makes a good developer, often you will get three different opinions.   With the exception of those shops that are purely development-centric (you guys have it much easier!), most other shops have management who have very little knowledge about the development process.  Their view can often be that development is simply a skill that one learns and then once aquired, that developer can produce widgets as good as the next like workers on an assembly-line floor.  On the other side, you have many developers that feel that software development is an art unto itself and that the ability to create the most pure design or know the most obscure of keywords or write the shortest-possible obfuscated piece of code is a good coder.  So is it a skill?  An Art?  Or something entirely in between?   Saying that software is merely a skill and one just needs to learn the syntax and tools would be akin to saying anyone who knows English and can use Word can write a 300 page book that is accurate, meaningful, and stays true to the point.  This just isn't so.  It takes more than mere skill to take words and form a sentence, join those sentences into paragraphs, and those paragraphs into a document.  I've interviewed candidates who could answer obscure syntax and keyword questions and once they were hired could not code effectively at all.  So development must be more than a skill.   But on the other end, we have art.  Is development an art?  Is our end result to produce art?  I can marvel at a piece of code -- see it as concise and beautiful -- and yet that code most perform some stated function with accuracy and efficiency and maintainability.  None of these three things have anything to do with art, per se.  Art is beauty for its own sake and is a wonderful thing.  But if you apply that same though to development it just doesn't hold.  I've had developers tell me that all that matters is the end result and how you code it is entirely part of the art and I couldn't disagree more.  Yes, the end result, the accuracy, is the prime criteria to be met.  But if code is not maintainable and efficient, it would be just as useless as a beautiful car that breaks down once a week or that gets 2 miles to the gallon.  Yes, it may work in that it moves you from point A to point B and is pretty as hell, but if it can't be maintained or is not efficient, it's not a good solution.  So development must be something less than art.   In the end, I think I feel like development is a matter of craftsmanship.  We use our tools and we use our skills and set about to construct something that satisfies a purpose and yet is also elegant and efficient.  There is skill involved, and there is an art, but really it boils down to being able to craft code.  Crafting code is far more than writing code.  Anyone can write code if they know the syntax, but so few people can actually craft code that solves a purpose and craft it well.  So this is what I want to find, I want to find code craftsman!  But how?   I used to ask coding-trivia questions a long time ago and many people still fall back on this.  The thought is that if you ask the candidate some piece of coding trivia and they know the answer it must follow that they can craft good code.  For example:   What C++ keyword can be applied to a class/struct field to allow it to be changed even from a const-instance of that class/struct?  (answer: mutable)   So what do we prove if a candidate can answer this?  Only that they know what mutable means.  One would hope that this would infer that they'd know how to use it, and more importantly when and if it should ever be used!  But it rarely does!  The problem with triva questions is that you will either: Approve a really good developer who knows what some obscure keyword is (good) Reject a really good developer who never needed to use that keyword or is too inexperienced to know how to use it (bad) Approve a really bad developer who googled "C++ Interview Questions" and studied like hell but can't craft (very bad) Many HR departments love these kind of tests because they are short and easy to defend if a legal issue arrises on hiring decisions.  After all it's easy to say a person wasn't hired because they scored 30 out of 100 on some trivia test.  But unfortunately, you've eliminated a large part of your potential developer pool and possibly hired a few duds.  There are times I've hired candidates who knew every trivia question I could throw out them and couldn't craft.  And then there are times I've interviewed candidates who failed all my trivia but who I took a chance on who were my best finds ever.    So if not trivia, then what?  Brain teasers?  The thought is, these type of questions measure the thinking power of a candidate.  The problem is, once again, you will either: Approve a good candidate who has never heard the problem and can solve it (good) Reject a good candidate who just happens not to see the "catch" because they're nervous or it may be really obscure (bad) Approve a candidate who has studied enough interview brain teasers (once again, you can google em) to recognize the "catch" or knows the answer already (bad). Once again, you're eliminating good candidates and possibly accepting bad candidates.  In these cases, I think testing someone with brain teasers only tests their ability to answer brain teasers, not the ability to craft code. So how do we measure someone's ability to craft code?  Here's a novel idea: have them code!  Give them a computer and a compiler, or a whiteboard and a pen, or paper and pencil and have them construct a piece of code.  It just makes sense that if we're going to hire someone to code we should actually watch them code.  When they're done, we can judge them on several criteria: Correctness - does the candidate's solution accurately solve the problem proposed? Accuracy - is the candidate's solution reasonably syntactically correct? Efficiency - did the candidate write or use the more efficient data structures or algorithms for the job? Maintainability - was the candidate's code free of obfuscation and clever tricks that diminish readability? Persona - are they eager and willing or aloof and egotistical?  Will they work well within your team? It may sound simple, or it may sound crazy, but when I'm looking to hire a developer, I want to see them actually develop well-crafted code.

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• Slick2d/Nifty-gui input

  - by eerongal

  I'm trying to get input from slick2d into nifty gui. Ive searched online, and I've seen a few examples, but I can't seem to get it working right. i've tried the example on here but I can't seem to get everything working. I'm not entirely sure what I'm doing wrong. I've also looked at examples using the JMonkeyEngine to help point me in the right direction, but still having issues with input. I can get everything else working like i need. Here's the code for my element controller: package gui; import java.util.Properties; import de.lessvoid.nifty.Nifty; import de.lessvoid.nifty.controls.Controller; import de.lessvoid.nifty.elements.Element; import de.lessvoid.nifty.input.NiftyInputEvent; import de.lessvoid.nifty.screen.Screen; import de.lessvoid.xml.xpp3.Attributes; public class BaseElementController implements Controller { private Element element; public void bind(Nifty arg0, Screen arg1, Element arg2, Properties arg3, Attributes arg4) { this.element = element; } public void init(Properties arg0, Attributes arg1) { // TODO Auto-generated method stub } public boolean inputEvent(NiftyInputEvent arg0) { // TODO Auto-generated method stub return false; } public void onFocus(boolean arg0) { // TODO Auto-generated method stub } public void onStartScreen() { // TODO Auto-generated method stub } public void test() { System.out.println("test"); } public void bam() { System.out.println("bam"); } } Here's my XML file: <?xml version="1.0" encoding="UTF-8" standalone="no"?> <nifty> <useStyles filename="nifty-default-styles.xml"/> <useControls filename="nifty-default-controls.xml"/> <screen id="screen2" controller="gui.BaseScreenController"> <layer backgroundColor="#fff0" childLayout="absolute" id="layer4" controller="gui.BaseElementController"> <panel childLayout="center" height="30%" id="panel1" style="nifty-panel-simple" width="50%" x="282" y="334" controller="gui.BaseElementController"> <control id="checkbox1" name="checkbox"/> <control childLayout="center" id="button2" label="button2" name="button" x="381" y="224" visibleToMouse="true" controller="gui.BaseElementController"> <interact onClick="bam()"/> </control> </panel> <text text="${CALL.getPlayerName()}" style="nifty-label" width="100%" height="100%" x="0" y="10" /> </layer> </screen> </nifty> Here's how I'm trying to bind the controller: public void init(GameContainer gc) throws SlickException { Input input = gc.getInput(); inputSystem = new PlainSlickInputSystem(); inputSystem.setInput(input); gui = new Gui(); gui.init(gc, inputSystem, "gui/tset.xml", "screen2"); input.removeListener(this); input.removeListener(inputSystem); input.addListener(inputSystem); } Essentially, all that happens right now is the screen loads up and displays, and it grabs the variable correctly in the label, but none of the input seems to be getting forwarded to Nifty from slick. I assume there's something I'm missing, but I can't seem to figure out what that is. In so far as what I have tried, I attempted to define a custom input listener to pick up events and assign that to my game in order to pick up input, which did not work, so i dropped that implementation, at current i'm trying to take the default inputs and bind then with a PlainSlickInputSystem and assigning that to the input (as shown in the first example link). On code execution, all the code is hit, and i've put several system.out.println's to get ouput of what is happening (the code above has been cleaned for presentation), and i even see the elements getting bound to the controller, yet it doesn't pick up controller events. As far as EXACTLY what's wrong, that I don't know, because I've followed all implementations i can find of this, and none of them seem to do anything it's like the input is just getting thrown out. None of the objects from niftyGui appear to be recognizing any input. Here is the binding from my objects at run time: ******INITIALIZED SCREEN: de.lessvoid.nifty.screen.Screen@4a1ab1c1 ******INITIALIZED ELEMENT: button2 (de.lessvoid.nifty.elements.Element@1e8c1be9) ******INITIALIZED ELEMENT: focusable => true, width => 100px {nifty-button#panel}, backgroundImage => button/button.png {nifty-button#panel}, label => button2, paddingLeft => 7px {nifty-button#panel}, imageMode => sprite-resize:100,23,0,2,96,2,2,2,96,2,19,2,96,2,2 {nifty-button#panel}, paddingRight => 7px {nifty-button#panel}, id => button2, visibleToMouse => true, height => 23px {nifty-button#panel}, style => nifty-button, name => button, inputMapping => de.lessvoid.nifty.input.mapping.MenuInputMapping, childLayout => center, controller => gui.BaseElementController, y => 224, x => 381 ******INITIALIZED SCREEN: de.lessvoid.nifty.screen.Screen@4a1ab1c1 ******INITIALIZED ELEMENT: panel1 (de.lessvoid.nifty.elements.Element@373ec894) ******INITIALIZED ELEMENT: id => panel1, height => 30%, style => nifty-panel-simple, width => 50%, backgroundImage => panel/nifty-panel-simple.png {nifty-panel-simple}, controller => gui.BaseElementController, childLayout => center, padding => 5px {nifty-panel-simple}, imageMode => resize:9,2,9,9,9,2,9,2,9,2,9,9 {nifty-panel-simple}, y => 334, x => 282 ******INITIALIZED SCREEN: de.lessvoid.nifty.screen.Screen@4a1ab1c1 ******INITIALIZED ELEMENT: layer4 (de.lessvoid.nifty.elements.Element@6427d489) ******INITIALIZED ELEMENT: id => layer4, backgroundColor => #fff0, controller => gui.BaseElementController, childLayout => absolute the button2 object is getting bound to my BaseElementController, but i can't seem to get it into the defined "onClick" call.

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• Custom Lookup Provider For NetBeans Platform CRUD Tutorial

  - by Geertjan

  For a long time I've been planning to rewrite the second part of the NetBeans Platform CRUD Application Tutorial to integrate the loosely coupled capabilities introduced in a seperate series of articles based on articles by Antonio Vieiro (a great series, by the way). Nothing like getting into the Lookup stuff right from the get go (rather than as an afterthought)! The question, of course, is how to integrate the loosely coupled capabilities in a logical way within that tutorial. Today I worked through the tutorial from scratch, up until the point where the prototype is completed, i.e., there's a JTextArea displaying data pulled from a database. That brought me to the place where I needed to be. In fact, as soon as the prototype is completed, i.e., the database connection has been shown to work, the whole story about Lookup.Provider and InstanceContent should be introduced, so that all the subsequent sections, i.e., everything within "Integrating CRUD Functionality" will be done by adding new capabilities to the Lookup.Provider. However, before I perform open heart surgery on that tutorial, I'd like to run the scenario by all those reading this blog who understand what I'm trying to do! (I.e., probably anyone who has read this far into this blog entry.) So, this is what I propose should happen and in this order: Point out the fact that right now the database access code is found directly within our TopComponent. Not good. Because you're mixing view code with data code and, ideally, the developers creating the user interface wouldn't need to know anything about the data access layer. Better to separate out the data access code into a separate class, within the CustomerLibrary module, i.e., far away from the module providing the user interface, with this content: public class CustomerDataAccess { public List<Customer> getAllCustomers() { return Persistence.createEntityManagerFactory("CustomerLibraryPU"). createEntityManager().createNamedQuery("Customer.findAll").getResultList(); } } Point out the fact that there is a concept of "Lookup" (which readers of the tutorial should know about since they should have followed the NetBeans Platform Quick Start), which is a registry into which objects can be published and to which other objects can be listening. In the same way as a TopComponent provides a Lookup, as demonstrated in the NetBeans Platform Quick Start, your own object can also provide a Lookup. So, therefore, let's provide a Lookup for Customer objects.  import org.openide.util.Lookup; import org.openide.util.lookup.AbstractLookup; import org.openide.util.lookup.InstanceContent; public class CustomerLookupProvider implements Lookup.Provider { private Lookup lookup; private InstanceContent instanceContent; public CustomerLookupProvider() { // Create an InstanceContent to hold capabilities... instanceContent = new InstanceContent(); // Create an AbstractLookup to expose the InstanceContent... lookup = new AbstractLookup(instanceContent); // Add a "Read" capability to the Lookup of the provider: //...to come... // Add a "Update" capability to the Lookup of the provider: //...to come... // Add a "Create" capability to the Lookup of the provider: //...to come... // Add a "Delete" capability to the Lookup of the provider: //...to come... } @Override public Lookup getLookup() { return lookup; } } Point out the fact that, in the same way as we can publish an object into the Lookup of a TopComponent, we can now also publish an object into the Lookup of our CustomerLookupProvider. Instead of publishing a String, as in the NetBeans Platform Quick Start, we'll publish an instance of our own type. And here is the type: public interface ReadCapability { public void read() throws Exception; } And here is an implementation of our type added to our Lookup: public class CustomerLookupProvider implements Lookup.Provider { private Set<Customer> customerSet; private Lookup lookup; private InstanceContent instanceContent; public CustomerLookupProvider() { customerSet = new HashSet<Customer>(); // Create an InstanceContent to hold capabilities... instanceContent = new InstanceContent(); // Create an AbstractLookup to expose the InstanceContent... lookup = new AbstractLookup(instanceContent); // Add a "Read" capability to the Lookup of the provider: instanceContent.add(new ReadCapability() { @Override public void read() throws Exception { ProgressHandle handle = ProgressHandleFactory.createHandle("Loading..."); handle.start(); customerSet.addAll(new CustomerDataAccess().getAllCustomers()); handle.finish(); } }); // Add a "Update" capability to the Lookup of the provider: //...to come... // Add a "Create" capability to the Lookup of the provider: //...to come... // Add a "Delete" capability to the Lookup of the provider: //...to come... } @Override public Lookup getLookup() { return lookup; } public Set<Customer> getCustomers() { return customerSet; } } Point out that we can now create a new instance of our Lookup (in some other module, so long as it has a dependency on the module providing the CustomerLookupProvider and the ReadCapability), retrieve the ReadCapability, and then do something with the customers that are returned, here in the rewritten constructor of the TopComponent, without needing to know anything about how the database access is actually achieved since that is hidden in the implementation of our type, above: public CustomerViewerTopComponent() { initComponents(); setName(Bundle.CTL_CustomerViewerTopComponent()); setToolTipText(Bundle.HINT_CustomerViewerTopComponent()); // EntityManager entityManager = Persistence.createEntityManagerFactory("CustomerLibraryPU").createEntityManager(); // Query query = entityManager.createNamedQuery("Customer.findAll"); // List<Customer> resultList = query.getResultList(); // for (Customer c : resultList) { // jTextArea1.append(c.getName() + " (" + c.getCity() + ")" + "\n"); // } CustomerLookupProvider lookup = new CustomerLookupProvider(); ReadCapability rc = lookup.getLookup().lookup(ReadCapability.class); try { rc.read(); for (Customer c : lookup.getCustomers()) { jTextArea1.append(c.getName() + " (" + c.getCity() + ")" + "\n"); } } catch (Exception ex) { Exceptions.printStackTrace(ex); } } Does the above make as much sense to others as it does to me, including the naming of the classes? Feedback would be appreciated! Then I'll integrate into the tutorial and do the same for the other sections, i.e., "Create", "Update", and "Delete". (By the way, of course, the tutorial ends up showing that, rather than using a JTextArea to display data, you can use Nodes and explorer views to do so.)

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• Source-control 'wet-work'?

  - by Phil Factor

  When a design or creative work is flawed beyond remedy, it is often best to destroy it and start again. The other day, I lost the code to a long and intricate SQL batch I was working on. I’d thought it was impossible, but it happened. With all the technology around that is designed to prevent this occurring, this sort of accident has become a rare event.  If it weren’t for a deranged laptop, and my distraction, the code wouldn’t have been lost this time.  As always, I sighed, had a soothing cup of tea, and typed it all in again.  The new code I hastily tapped in  was much better: I’d held in my head the essence of how the code should work rather than the details: I now knew for certain  the start point, the end, and how it should be achieved. Instantly the detritus of half-baked thoughts fell away and I was able to write logical code that performed better.  Because I could work so quickly, I was able to hold the details of all the columns and variables in my head, and the dynamics of the flow of data. It was, in fact, easier and quicker to start from scratch rather than tidy up and refactor the existing code with its inevitable fumbling and half-baked ideas. What a shame that technology is now so good that developers rarely experience the cleansing shock of losing one’s code and having to rewrite it from scratch.  If you’ve never accidentally lost  your code, then it is worth doing it deliberately once for the experience. Creative people have, until Technology mistakenly prevented it, torn up their drafts or sketches, threw them in the bin, and started again from scratch.  Leonardo’s obsessive reworking of the Mona Lisa was renowned because it was so unusual:  Most artists have been utterly ruthless in destroying work that didn’t quite make it. Authors are particularly keen on writing afresh, and the results are generally positive. Lawrence of Arabia actually lost the entire 250,000 word manuscript of ‘The Seven Pillars of Wisdom’ by accidentally leaving it on a train at Reading station, before rewriting a much better version.  Now, any writer or artist is seduced by technology into altering or refining their work rather than casting it dramatically in the bin or setting a light to it on a bonfire, and rewriting it from the blank page.  It is easy to pick away at a flawed work, but the real creative process is far more brutal. Once, many years ago whilst running a software house that supplied commercial software to local businesses, I’d been supervising an accounting system for a farming cooperative. No packaged system met their needs, and it was all hand-cut code.  For us, it represented a breakthrough as it was for a government organisation, and success would guarantee more contracts. As you’ve probably guessed, the code got mangled in a disk crash just a week before the deadline for delivery, and the many backups all proved to be entirely corrupted by a faulty tape drive.  There were some fragments left on individual machines, but they were all of different versions.  The developers were in despair.  Strangely, I managed to re-write the bulk of a three-month project in a manic and caffeine-soaked weekend.  Sure, that elegant universally-applicable input-form routine was‘nt quite so elegant, but it didn’t really need to be as we knew what forms it needed to support.  Yes, the code lacked architectural elegance and reusability. By dawn on Monday, the application passed its integration tests. The developers rose to the occasion after I’d collapsed, and tidied up what I’d done, though they were reproachful that some of the style and elegance had gone out of the application. By the delivery date, we were able to install it. It was a smaller, faster application than the beta they’d seen and the user-interface had a new, rather Spartan, appearance that we swore was done to conform to the latest in user-interface guidelines. (we switched to Helvetica font to look more ‘Bauhaus’ ). The client was so delighted that he forgave the new bugs that had crept in. I still have the disk that crashed, up in the attic. In IT, we have had mixed experiences from complete re-writes. Lotus 123 never really recovered from a complete rewrite from assembler into C, Borland made the mistake with Arago and Quattro Pro  and Netscape’s complete rewrite of their Navigator 4 browser was a white-knuckle ride. In all cases, the decision to rewrite was a result of extreme circumstances where no other course of action seemed possible.   The rewrite didn’t come out of the blue. I prefer to remember the rewrite of Minix by young Linus Torvalds, or the rewrite of Bitkeeper by a slightly older Linus.  The rewrite of CP/M didn’t do too badly either, did it? Come to think of it, the guy who decided to rewrite the windowing system of the Xerox Star never regretted the decision. I’ll agree that one should often resist calls for a rewrite. One of the worst habits of the more inexperienced programmer is to denigrate whatever code he or she inherits, and then call loudly for a complete rewrite. They are buoyed up by the mistaken belief that they can do better. This, however, is a different psychological phenomenon, more related to the idea of some motorcyclists that they are operating on infinite lives, or the occasional squaddies that if they charge the machine-guns determinedly enough all will be well. Grim experience brings out the humility in any experienced programmer.  I’m referring to quite different circumstances here. Where a team knows the requirements perfectly, are of one mind on methodology and coding standards, and they already have a solution, then what is wrong with considering  a complete rewrite? Rewrites are so painful in the early stages, until that point where one realises the payoff, that even I quail at the thought. One needs a natural disaster to push one over the edge. The trouble is that source-control systems, and disaster recovery systems, are just too good nowadays.   If I were to lose this draft of this very blog post, I know I’d rewrite it much better. However, if you read this, you’ll know I didn’t have the nerve to delete it and start again.  There was a time that one prayed that unreliable hardware would deliver you from an unmaintainable mess of a codebase, but now technology has made us almost entirely immune to such a merciful act of God. An old friend of mine with long experience in the software industry has long had the idea of the ‘source-control wet-work’,  where one hires a malicious hacker in some wild eastern country to hack into one’s own  source control system to destroy all trace of the source to an application. Alas, backup systems are just too good to make this any more than a pipedream. Somehow, it would be difficult to promote the idea. As an alternative, could one construct a source control system that, on doing all the code-quality metrics, would systematically destroy all trace of source code that failed the quality test? Alas, I can’t see many managers buying into the idea. In reading the full story of the near-loss of Toy Story 2, it set me thinking. It turned out that the lucky restoration of the code wasn’t the happy ending one first imagined it to be, because they eventually came to the conclusion that the plot was fundamentally flawed and it all had to be rewritten anyway.  Was this an early  case of the ‘source-control wet-job’?’ It is very hard nowadays to do a rapid U-turn in a development project because we are far too prone to cling to our existing source-code.

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• SQL Sentry First Impressions

  - by AjarnMark

  After struggling to defend my SQL Servers from a political attack recently, I realized that I needed better tools to back me up, and SQL Sentry is the leading candidate. A couple of weeks ago, seemingly from out of nowhere, complaints from the business users started coming in that one of the core internal applications was running dramatically slower than normal, and fingers were being pointed at the SQL Server.  Unfortunately, we don’t have a production DBA whose entire job is to monitor and maintain our SQL Servers.  The responsibility falls to me to do the best I can, investing only a small portion of my time, because there are so many other responsibilities to take care of, and our industry is still deep in recession.  I inherited these SQL Servers and have made significant improvements in process and procedure, but I had not yet made the time to take real baseline measurements or keep a really close eye on the performance.  Like many DBAs, I wrote several of my own tools and used the “built-in tools” like Profiler, PerfMon, and sp_who2 (did I mention most of our instances are SQL Server 2000?).  These have all served me well for in-the-moment troubleshooting and maintenance, but they really fell down on the job when I was called upon to “prove” that SQL Server performance was acceptable and more importantly had not degraded recently (i.e. historical comparisons).  I really didn’t have anything from a historical comparison perspective, but I was able to show that current performance was acceptable, and deflect attention back onto other components (which in fact turned out to be the real culprit). That experience dramatically illustrated the need for better monitoring tools.  Coincidentally, I had been talking recently to my boss about the mini nightmare of monitoring several critical and interdependent overnight jobs that operate on separate instances of SQL Server.  Among other tools, I had been using Idera’s SQL Job Manager which is a free tool and did a nice job of showing me job schedules and histories in a nice calendar view.  This worked fairly well, and for the money (did I mention it was free?) it couldn’t be beat.  But it is based on the stored job history in MSDB, and there were other performance problems that we ran into when we started changing the settings for how much job history to retain, in order to be able to look back a month or more in the calendar view.  Another coincidence (if you believe in such things) was that when we had some of those performance challenges, I posted a couple of questions to the #sqlhelp hashtag on Twitter and Greg Gonzalez (@SQLSensei) suggested I check out SQL Sentry’s Event Manager.  At the time, I just thought he worked there, but later found out that he founded the company.  When I took a quick look at the features & benefits, the one that really jumped out at me is Chaining and Queueing which sounded like it would really help with our “interdependent jobs on different servers” issue. I know that is a lot of background story and coincidences, but hopefully you have stuck with me so far, and now we have arrived at the point where last week I downloaded and installed the 30-day trial of the SQL Sentry Power Suite, which is Event Manager plus Performance Advisor.  And I must say that I really like what I see so far.  Here are a few highlights: Great Support.  I had two issues getting the trial setup and monitoring a handful of our servers.  One of which was entirely my fault (missed a security setting in SQL 2008) and the other was mostly my fault (late change to some config settings that were apparently cached and did not get refreshed properly).  In both cases, the support staff at SQL Sentry were very responsive and rather quickly figured out what the cause and fix was for each of them.  This left me with a great impression of the company.  Kudos to them! Chaining and Queueing.  While I have not yet activated this feature, I am very excited about the possibilities.  We have jobs on three different instances of SQL Server that have to be run in a certain order, and each has to finish before the next can successfully begin, and I believe this feature will ensure just that.  It has been a real pain in the backside when one of those jobs runs just a little too long and does not finish before the job on another instance starts, thus triggering a chain reaction of either outright job failures, or worse, successful completion of completely invalid processing. Calendar View.  I really, really like the Event Manager calendar view where I can see all jobs and events across all instances and identify potential resource contention as well as windows of opportunity for maintenance activity.  Very well done, and based on Event Manager’s own database of accumulated historical information rather than querying the source instances every time. Performance Advisor Dashboard History View.  This view let’s me quickly select a date and time range and it displays graphs of key SQL Server and Windows metrics.  This is exactly the thing I needed to answer the “has performance changed recently” question at the beginning of this post. Reporting Services Subscription Jobs with Report Name.  This was a big and VERY pleasant surprise.  If you have ever looked at the list of SQL Server jobs that SQL Server Reporting Services creates when you make a Subscription, you will notice that they all have some sort of GUID as the name of the job.  This is really ugly, and really annoying because when you are just looking at the SQL Agent and Job Activity Monitor, if you see that Job X failed, you really do not have any indication in the name or the properties of the Job itself, as to what Report that was for.  But with SQL Sentry Event Manager you do.  The Jobs list in the Navigator pane in SQL Sentry, amazingly, displays the name of the Report that the Subscription Job is for.  And when you open it to see more details, it shows you the full Reporting Services path to that Report, so you can immediately track it down in the Report Manager in case you want to identify/notify the owner or edit the Subscription information.  I did not expect this at all, but I sure do like it.  HOORAY! That is just my first impressions from using the tools for a few days.  And I haven’t even gotten into how it showed me where I was completely mistaken about one aspect of my SQL Server disk configurations.  I’ll share that lesson in another blog entry.  But I have to say it again, the combination of Event Manager and Performance Advisor working together have really made me a fan.

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• Quaternion Camera Orbiting around a Sphere

  - by jessejuicer

  Background: I'm trying to create a game where the camera is always rotating around a single sphere. I'm using the DirectX D3DX math functions in C++ on Windows. The Problem: I cannot get both the camera position and orientation both working properly at the same time. Either one works but not both together. Here's the code for my quaternion camera that revolves around a sphere, always looking at the centerpoint of the sphere, ... as far as I understand it (but which isn't working properly): (I'm only going to present rotation around the X axis here, to simplify this post) Whenever the UP key is pressed or held down, the camera should rotate around the X axis, while looking at the centerpoint of the sphere (which is at 0,0,0 in the world). So, I build a quaternion that represents a small angle of rotation around the x axis like this (where 'deltaAngle' is a small enough number for a slow rotation): D3DXVECTOR3 rotAxis; D3DXQUATERNION tempQuat; tempQuat.x = 0.0f; tempQuat.y = 0.0f; tempQuat.z = 0.0f; tempQuat.w = 1.0f; rotAxis.x = 1.0f; rotAxis.y = 0.0f; rotAxis.z = 0.0f; D3DXQuaternionRotationAxis(&tempQuat, &rotAxis, deltaAngle); ...and I accumulate the result into the camera's current orientation quat, like this: D3DXQuaternionMultiply(&cameraOrientationQuat, &cameraOrientationQuat, &tempQuat); ...which all works fine. Now I need to build a view matrix to pass to DirectX SetTransform function. So I build a rotation matrix from the camera orientation quat as follows: D3DXMATRIXA16 rotationMatrix; D3DXMatrixIdentity(&rotationMatrix); D3DXMatrixRotationQuaternion(&rotationMatrix, &cameraOrientationQuat); ...Now (as seen below) if I just transpose that rotationMatrix and plug it into the 3x3 section of the view matrix, then negate the camera's position and plug it into the translation section of the view matrix, the rotation magically works. Perfectly. (even when I add in rotations for all three axes). There's no gimbal lock, just a smooth rotation all around in any direction. BUT- this works even though I never change the camera's position. At all. Which sorta blows my mind. I even display the camera position and can watch it stay constant at it's starting point (0.0, 0.0, -4000.0). It never moves, but the rotation around the sphere is perfect. I don't understand that. For proper view rotation, the camera position should be revolving around the sphere. Here's the rest of building the view matrix (I'll talk about the commented code below). Note that the camera starts out at (0.0, 0.0, -4000.0) and m_camDistToTarget is 4000.0: /* D3DXVECTOR3 vec1; D3DXVECTOR4 vec2; vec1.x = 0.0f; vec1.y = 0.0f; vec1.z = -1.0f; D3DXVec3Transform(&vec2, &vec1, &rotationMatrix); g_cameraActor->pos.x = vec2.x * g_cameraActor->m_camDistToTarget; g_cameraActor->pos.y = vec2.y * g_cameraActor->m_camDistToTarget; g_cameraActor->pos.z = vec2.z * g_cameraActor->m_camDistToTarget; */ D3DXMatrixTranspose(&g_viewMatrix, &rotationMatrix); g_viewMatrix._41 = -g_cameraActor->pos.x; g_viewMatrix._42 = -g_cameraActor->pos.y; g_viewMatrix._43 = -g_cameraActor->pos.z; g_viewMatrix._44 = 1.0f; g_direct3DDevice9->SetTransform( D3DTS_VIEW, &g_viewMatrix ); ...(The world matrix is always an identity, and the perspective projection works fine). ...So, without the commented code being compiled, the rotation works fine. But to be proper, for obvious reasons, the camera position should be rotating around the sphere, which it currently is not. That's what the commented code is supposed to do. And when I add in that chunk of code to do that, and look at all the data as I hold the keys down (using UP, DOWN, LEFT, RIGHT to rotate different directions) all the values look correct! The camera position is rotating around the sphere just fine, and I can watch that happen visually too. The problem is that the camera orientation does not lookat the center of the sphere. It always looks straight forward down the z axis (toward positive z) as it revolves around the sphere. Yet the values of both the rotation matrix and the view matrix seem to be behaving correctly. (The view matrix orientation is the same as the rotation matrix, just transposed). For instance if I just hold down the key to spin around the x axis, I can watch the values of the three axes represented in the view matrix (x, y, and z axes)... view x-axis stays at (1.0, 0.0, 0.0), and view y-axis and z-axis both spin around the x axis just fine. All the numbers are changing as they should be... well, almost. As far as I can tell, the position of the view matrix is spinning around the sphere one direction (like clockwise), and the orientation (the axes in the view matrix) are spinning the opposite direction (like counter-clockwise). Which I guess explains why the orientation appears to stay straight ahead. I know the position is correct. It revolves properly. It's the orientation that's wrong. Can anyone see what am I doing wrong? Am I using these functions incorrectly? Or is my algorithm flawed? As usual I've been combing my code for simple mistakes for many hours. I'm willing to post the actual code, and a video of the behavior, but that will take much more effort. Thought I'd ask this way first.

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• Learnings from trying to write better software: Loud errors from the very start

  - by theo.spears

  Microsoft made a very small number of backwards incompatible changes between .NET 1.1 and 2.0, because they wanted to make it as easy and safe as possible to port applications to the new runtime. (Here’s a list.) However, one thing they did change was what happens when a background thread fails with an unhanded exception - in .NET 1.1 nothing happened, the thread terminated, and the application continued oblivious. Try the same trick in .NET 2.0 and the entire application, including all threads, will rudely terminate. There are three reasons for this. Firstly if a background thread has crashed, it may have left the entire application in an inconsistent state, in a way that will affect other threads. It’s better to terminate the entire application than continue and have the application perform actions based on a broken state, for example take customer orders, or write corrupt files to disk.  Secondly, during software development, it is far better for errors to be loud and obtrusive. Even if you have unit tests and integration tests (and you should), a key part of ensuring software works properly is to actually try using it, both through systematic testing and through the casual use all software gets by its developers during use. Subtle errors are easy to miss if you are not actually doing real work using the application, loud errors are obvious. Thirdly, and most importantly, even if catching and swallowing exceptions indiscriminately doesn't cause any problems in your application, the presence of unexpected exceptions shows you do not fully understand the behavior of your code. The currently released version of your application may be absolutely correct. However, because your mental model of the behavior is wrong, any future change you make to the program could and probably will introduce critical errors.  This applies to more than just exceptions causing threads to exit, any unexpected state should make the application blow up in an un-ignorable way. The worst thing you can do is silently swallow errors and continue. And let's be clear, writing to a log file does not count as blowing up in an un-ignorable way.  This is all simple as long as the call stack only contains your code, but when your functions start to be called by third party or .NET framework code, it's surprisingly easy for exceptions to start vanishing. Let's look at two examples.   1. Windows forms drag drop events  Usually if you throw an exception from a winforms event handler it will bring up the "application has crashed" dialog with abort and continue options. This is a good default behavior - the error is big and loud, but it is possible for the user to ignore the error and hopefully save their data, if somehow this bug makes it past testing. However drag and drop are different - throw an exception from one of these and it will just be silently swallowed with no explanation.  By the way, it's not just drag and drop events. Timer events do it too.  You can research how exceptions are treated in different handlers and code appropriately, but the safest and most user friendly approach is to always catch exceptions in your event handlers and show your own error message. I'll talk about one good approach to handling these exceptions at the end of this post.   2. SSMS integration for SQL Tab Magic  A while back wrote an SSMS add-in called SQL Tab Magic (learn more about the process here). It works by listening to certain SSMS events and remembering what documents are opened and closed. I deployed it internally and it was used for a few months by a number of people without problems, so I was reasonably confident in its quality. Before releasing I made a few cleanups, including introducing error reporting. Bam. A few days later I was looking at over 1,000 error reports in my inbox. In turns out I wasn't handling table designers properly. The exceptions were there, but again SSMS was helpfully swallowing them all for me, so I was blissfully unaware. Had I made my errors loud from the start, I would have noticed these issues long before and fixed them.   Handling exceptions  Now you are systematically catching exceptions throughout your application, you need to do something with them. I've tried 3 options: log them, alert the user, and automatically send them home.  There are a few good options for logging in .NET. The most widespread is Apache log4net, which provides a very capable and configurable logging framework. There is also NLog which has a compatible interface, with a greater emphasis on fluent rather than XML configuration.  Alerting the user serves two purposes. Firstly it means they understand their action has failed to they don't just assume it worked (Silent file copy failure is a problem if you then delete the originals) or that they should keep waiting for a background task to complete. Secondly, it means the users can report the bug to your support team, and then you can fix it. This means the message you show the user should contain the information you need as a developer to identify and fix it. And the user will probably just send you a screenshot of the dialog, so it shouldn't be hidden by scroll bars.  This leads us to the third option, automatically sending error reports home. By automatic I mean with minimal effort on the part of the user, rather than doing it silently behind their backs. The advantage of this is you can send back far more detailed and precise information than you can expect a user to include in an email, and by making it easier to report errors, you make it more likely users will do so.  We do this using a great tool called SmartAssembly (full disclosure: this is a product made by Red Gate). It captures complete stack traces including the values of all local variables and then allows the user to send all this information back with a single click. We also capture log files to help understand what lead up to the error. We then use the free SmartAssembly Sync for Jira to dedupe these reports and raise them as bugs in our bug tracking system.  The combined effect of loud errors during development and then automatic error reporting once software is deployed allows us to find and fix more bugs, correct misunderstandings on how our software works, and overall is a key piece in delivering higher quality software. However it is no substitute for having motivated cunning testers in the building - and we're looking to hire more of those too.   If you found this post interesting you should follow me on twitter.  

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• Corsair Hackers Reboot

  It wasn't easy for me to attend but it was absolutely worth to go. The Linux User Group of Mauritius (LUGM) organised another get-together for any open source enthusiast here on the island. Strangely named "Corsair Hackers Reboot" but it stands for a positive cause: "Corsair Hackers Reboot Event A collaborative activity involving LUGM, UoM Computer Club, Fortune Way Shopping Mall and several geeks from around the island, striving to put FOSS into homes & offices. The public is invited to discover and explore Free Software & Open Source." And it was a good opportunity for me and the kids to visit the east coast of Mauritius, too. Perfect timing It couldn't have been better... Why? Well, for two important reasons (in terms of IT): End of support for Microsoft Windows XP - 08.04.2014 Release of Ubuntu 14.04 Long Term Support - 17.04.2014 Quite funnily, those two IT dates weren't the initial reasons and only during the weeks of preparations we put those together. And therefore it was even more positive to promote the use of Linux and open source software in general to a broader audience. Getting there ... Thanks to the new motor way M3 and all the additional road work which has been completed recently it was very simple to get across the island in a very quick and relaxed manner. Compared to my trips in the early days of living in Mauritius (and riding on a scooter) it was very smooth and within less than an hour we hit Centrale de Flacq. Well, being in the city doesn't necessarily mean that one has arrived at the destination. But thanks to modern technology I had a quick look on Google Maps, and we finally managed to get a parking behind the huge bus terminal in Flacq. From there it was just a short walk to Fortune Way. The children were trying to count the number of buses... Well, lots and lots of buses - really impressive actually. What was presented? There were different areas set up. Right at the entrance one's attention was directly drawn towards the elevated hacker's stage. Similar to rock stars performing their gig there was bunch of computers, laptops and networking equipment in order to cater the right working conditions for coding/programming challenge(s) on the one hand and for the pen-testing or system hacking competition on the other hand. Personally, I was very impresses that actually Nitin took care of the pen-testing competition. He hardly started one year back with Linux in general, and Kali Linux specifically. Seeing his personal development from absolute newbie to a decent Linux system administrator within such a short period of time, is really impressive. His passion to open source software made him a living. Next, clock-wise seen, was the Kid's Corner with face-painting as the main attraction. Additionally, there were numerous paper print outs to colour. Plus a decent workstation with the educational suite GCompris. Of course, my little ones were into that. They already know GCompris since a while as they are allowed to use it on an IGEL thin client terminal here at home. To simplify my life, I set up GCompris as full-screen guest session on the server, and they can pass the login screen without any further obstacles. And because it's a thin client hooked up to a XDMCP remote session I don't have to worry about the hardware on their desk, too. The next section was the main attraction of the event: BYOD - Bring Your Own Device Well, compared to the usual context of BYOD the corsairs had a completely different intention. Here, you could bring your own laptop and a team of knowledgeable experts - read: geeks and so on - offered to fully convert your system on any Linux distribution of your choice. And even though I came later, I was told that the USB pen drives had been in permanent use. From being prepared via dd command over launching LiveCD session to finally installing a fresh Linux system on bare metal. Most interestingly, I did a similar job already a couple of months ago, while upgrading an existing Windows XP system to Xubuntu 13.10. So far, the female owner is very happy and enjoys her system almost every evening to go shopping online, checking mails, and reading latest news from the Anime world. Back to the Hackers event, Ish told me that they managed approximately 20 conversion during the day. Furthermore, Ajay and others gladly assisted some visitors with some tricky issues and by the end of the day you can call is a success. While I was around, there was a elderly male visitor that got a full-fledged system conversion to a Linux system running completely in French language. A little bit more to the centre it was Yasir's turn to demonstrate his Arduino hardware that he hooked up with an experimental electrical circuit board connected to an LCD matrix display. That's the real spirit of hacking, and he showed some minor adjustments on the fly while demo'ing the system. Also, very interesting there was a thermal sensor around. Personally, I think that platforms like the Arduino as well as the Raspberry Pi have a great potential at a very affordable price in order to bring a better understanding of electronics as well as computer programming to a broader audience. It would be great to see more of those experiments during future activities. And last but not least there were a small number of vendors. Amongst them was Emtel - once again as sponsor of the general internet connectivity - and another hardware supplier from Riche Terre shopping mall. They had a good collection of Android related gimmicks, like a autonomous web cam that can convert any TV with HDMI connector into an online video chat system given WiFi. It's actually kind of awesome to have a Skype or Google hangout video session on the big screen rather than on the laptop. Some pictures of the event LUGM: Great conversations on Linux, open source and free software during the Corsair Hackers Reboot LUGM: Educational workstation running GCompris suite attracted the youngest attendees of the day. Of course, face painting had to be done prior to hacking... LUGM: Nadim demoing some Linux specifics to interested visitors. Everyone was pretty busy during the whole day LUGM: The hacking competition, here pen-testing a wireless connection and access point between multiple machines LUGM: Well prepared workstations to be able to 'upgrade' visitors' machines to any Linux operating system Final thoughts Gratefully, during the preparations of the event I was invited to leave some comments or suggestions, and the team of the LUGM did a great job. The outdoor banner was a eye-catcher, the various flyers and posters for the event were clearly written and as far as I understood from the quick chats I had with Ish, Nadim, Nitin, Ajay, and of course others all were very happy about the event execution. Great job, LUGM! And I'm already looking forward to the next Corsair Hackers Reboot event ... Crossing fingers: Very soon and hopefully this year again :) Update: In the media The event had been announced in local media, too. L'Express: Salon informatique: Hacking Challenge à Flacq

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• Source-control 'wet-work'?

  - by Phil Factor

  When a design or creative work is flawed beyond remedy, it is often best to destroy it and start again. The other day, I lost the code to a long and intricate SQL batch I was working on. I’d thought it was impossible, but it happened. With all the technology around that is designed to prevent this occurring, this sort of accident has become a rare event.  If it weren’t for a deranged laptop, and my distraction, the code wouldn’t have been lost this time.  As always, I sighed, had a soothing cup of tea, and typed it all in again.  The new code I hastily tapped in  was much better: I’d held in my head the essence of how the code should work rather than the details: I now knew for certain  the start point, the end, and how it should be achieved. Instantly the detritus of half-baked thoughts fell away and I was able to write logical code that performed better.  Because I could work so quickly, I was able to hold the details of all the columns and variables in my head, and the dynamics of the flow of data. It was, in fact, easier and quicker to start from scratch rather than tidy up and refactor the existing code with its inevitable fumbling and half-baked ideas. What a shame that technology is now so good that developers rarely experience the cleansing shock of losing one’s code and having to rewrite it from scratch.  If you’ve never accidentally lost  your code, then it is worth doing it deliberately once for the experience. Creative people have, until Technology mistakenly prevented it, torn up their drafts or sketches, threw them in the bin, and started again from scratch.  Leonardo’s obsessive reworking of the Mona Lisa was renowned because it was so unusual:  Most artists have been utterly ruthless in destroying work that didn’t quite make it. Authors are particularly keen on writing afresh, and the results are generally positive. Lawrence of Arabia actually lost the entire 250,000 word manuscript of ‘The Seven Pillars of Wisdom’ by accidentally leaving it on a train at Reading station, before rewriting a much better version.  Now, any writer or artist is seduced by technology into altering or refining their work rather than casting it dramatically in the bin or setting a light to it on a bonfire, and rewriting it from the blank page.  It is easy to pick away at a flawed work, but the real creative process is far more brutal. Once, many years ago whilst running a software house that supplied commercial software to local businesses, I’d been supervising an accounting system for a farming cooperative. No packaged system met their needs, and it was all hand-cut code.  For us, it represented a breakthrough as it was for a government organisation, and success would guarantee more contracts. As you’ve probably guessed, the code got mangled in a disk crash just a week before the deadline for delivery, and the many backups all proved to be entirely corrupted by a faulty tape drive.  There were some fragments left on individual machines, but they were all of different versions.  The developers were in despair.  Strangely, I managed to re-write the bulk of a three-month project in a manic and caffeine-soaked weekend.  Sure, that elegant universally-applicable input-form routine was‘nt quite so elegant, but it didn’t really need to be as we knew what forms it needed to support.  Yes, the code lacked architectural elegance and reusability. By dawn on Monday, the application passed its integration tests. The developers rose to the occasion after I’d collapsed, and tidied up what I’d done, though they were reproachful that some of the style and elegance had gone out of the application. By the delivery date, we were able to install it. It was a smaller, faster application than the beta they’d seen and the user-interface had a new, rather Spartan, appearance that we swore was done to conform to the latest in user-interface guidelines. (we switched to Helvetica font to look more ‘Bauhaus’ ). The client was so delighted that he forgave the new bugs that had crept in. I still have the disk that crashed, up in the attic. In IT, we have had mixed experiences from complete re-writes. Lotus 123 never really recovered from a complete rewrite from assembler into C, Borland made the mistake with Arago and Quattro Pro  and Netscape’s complete rewrite of their Navigator 4 browser was a white-knuckle ride. In all cases, the decision to rewrite was a result of extreme circumstances where no other course of action seemed possible.   The rewrite didn’t come out of the blue. I prefer to remember the rewrite of Minix by young Linus Torvalds, or the rewrite of Bitkeeper by a slightly older Linus.  The rewrite of CP/M didn’t do too badly either, did it? Come to think of it, the guy who decided to rewrite the windowing system of the Xerox Star never regretted the decision. I’ll agree that one should often resist calls for a rewrite. One of the worst habits of the more inexperienced programmer is to denigrate whatever code he or she inherits, and then call loudly for a complete rewrite. They are buoyed up by the mistaken belief that they can do better. This, however, is a different psychological phenomenon, more related to the idea of some motorcyclists that they are operating on infinite lives, or the occasional squaddies that if they charge the machine-guns determinedly enough all will be well. Grim experience brings out the humility in any experienced programmer.  I’m referring to quite different circumstances here. Where a team knows the requirements perfectly, are of one mind on methodology and coding standards, and they already have a solution, then what is wrong with considering  a complete rewrite? Rewrites are so painful in the early stages, until that point where one realises the payoff, that even I quail at the thought. One needs a natural disaster to push one over the edge. The trouble is that source-control systems, and disaster recovery systems, are just too good nowadays.   If I were to lose this draft of this very blog post, I know I’d rewrite it much better. However, if you read this, you’ll know I didn’t have the nerve to delete it and start again.  There was a time that one prayed that unreliable hardware would deliver you from an unmaintainable mess of a codebase, but now technology has made us almost entirely immune to such a merciful act of God. An old friend of mine with long experience in the software industry has long had the idea of the ‘source-control wet-work’,  where one hires a malicious hacker in some wild eastern country to hack into one’s own  source control system to destroy all trace of the source to an application. Alas, backup systems are just too good to make this any more than a pipedream. Somehow, it would be difficult to promote the idea. As an alternative, could one construct a source control system that, on doing all the code-quality metrics, would systematically destroy all trace of source code that failed the quality test? Alas, I can’t see many managers buying into the idea. In reading the full story of the near-loss of Toy Story 2, it set me thinking. It turned out that the lucky restoration of the code wasn’t the happy ending one first imagined it to be, because they eventually came to the conclusion that the plot was fundamentally flawed and it all had to be rewritten anyway.  Was this an early  case of the ‘source-control wet-job’?’ It is very hard nowadays to do a rapid U-turn in a development project because we are far too prone to cling to our existing source-code.

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• Reviewing Retail Predictions for 2011

  - by David Dorf

  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:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} I've been busy thinking about what 2012 and beyond will look like for retail, and I have some interesting predictions to share.  But before I go there, let’s first review this year’s predictions before making new ones for 2012. 1. Alternate Payments We've seen several alternate payment schemes emerge over the last two years, and 2011 may be the year one of them takes hold. Any competition that can drive down fees will be good for everyone. I'm betting that Apple will add NFC chips to their next version of the iPhone, then enable payments in stores using iTunes accounts on the backend. Paypal will continue to make inroads, and Isis will announce a pilot. The iPhone 4S did not contain an NFC chip, so we’ll have to continuing waiting for the iPhone 5. PayPal announced its moving into in-store payments, and Google launched its wallet in selected cities.  Overall I think the payment scene is heating up and that trend will continue. 2. Engineered Systems The industry is moving toward purpose-built appliances that are optimized across the entire stack. Oracle calls these "engineered systems" and the first two examples are Exadata and Exalogic, but there are other examples from other vendors. These are particularly important to the retail industry because of the volume of data that must be processed. There should be continued adoption in 2011. Oracle reports that Exadata is its fasting growing product, and at the recent OpenWorld it announced the SuperCluster and Exalytics products, both continuing the engineered systems trend. SAP’s HANA continues to receive attention, and IBM also seems to be moving in this direction. 3. Social Analytics There are lots of tools that provide insight into how a brand is perceived across popular internet sites, but as far as I know, these tools are not industry specific. The next step needs to mine the data and determine how it should influence retail operations. The data needs to help retailers determine how they create promotions, which products to stock, and how to keep consumers engaged. Social data alone does not provide the answers, but its one more data point that will help retailers make better decisions. Look for some vendor consolidation to help make this happen. In March, Salesforce.com acquired leading social monitoring vendor Radian6 and followed up with acquisitions of Heroku and Model Metrics. The notion of Social CRM seems to be going more mainstream now. 4. 2-D Barcodes Look for more QRCodes on shelf-tags, in newspaper circulars, and on billboards. It's a great portal from the physical world into the digital one that buys us time until augmented reality matures further. Nobody wants to type "www", backslash, and ".com" on their phones. QRCodes are everywhere. ‘Nuff said. 5. In the words of Microsoft, "To the Cloud!" My favorite "cloud application" is Evernote. If you take notes on your work laptop, you will inevitably need those notes on your home PC. And if you manage to solve that problem, you'll need to access them from your mobile phone. Evernote stores your notes in the cloud and provides easy ways to access them. Being able to access a service from anywhere and not having to worry about backups, upgrades, etc. is great. Retailers will start to rely on cloud services, both public and private, in the coming year. There were no shortage of announcements in this area: Amazon’s cloud-based Kindle Fire, Apple’s iCloud, Oracle’s Public Cloud, etc. I saw an interesting presentation showing how BevMo moved their systems to the cloud.  Seems like retailers are starting to consider the cloud for specific uses. 6. F-CommerceTop of Form Move over "E" and "M" so we can introduce "F-Commerce," which should go mainstream in 2011. Already several retailers have created small stores on Facebook, and it won't be long before Facebook becomes a full-fledged channel in the omni-channel world of retail. The battle between Facebook and Google will heat up over retail, where both stand to make lots of money. JCPenney and ASOS both put their entire catalogs on Facebook, and lots of other retailers have connected Facebook to their e-commerce site. I still think selling from the newsfeed is the best approach, and several retailers are trying that approach as well. I just don’t see Google+ as a threat to Facebook, so I think that battle is over.  I called 2011 The Year of F-Commerce, and that was probably accurate. Its good to look back at predictions, but we also have to think about what was missed.  I didn't see Amazon entering the tablet business with such a splash, although in hindsight it was obvious. Nor did I think HP would fall so far so fast.  Look for my 2012 predictions coming soon.

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• Silverlight IConvertible TypeConverter

  - by codingbloke

  I recently answered the following question on stackoverflow:  Silverlight 3 custom control: only ‘int’ as numeric type for a property? [e.g. long or int64 seems to break] I quickly knocked up the class ConvertibleTypeConverter<T> that I posted in the question (listed later here as well). Afterward I fully expected to find that of the usual clever “bods who blog” to have covered this probably with a better solution than I.  So far though I’ve not found one so I thought I’d blog it myself. The Problem Here is a classic gotcha I’ve seen asked more than once on stackoverflow :- public class MyClass {     public float SomeValue { get; set; } } <local:MyClass SomeValue="45.15" /> This fails with the error  “Failed to create a 'System.Single' from the text '45.15'”  and results in much premature hair loss.  Fortunately this is SL4, in SL3 the error message is almost meaningless.  So what gives, how can it be that this fails when we can see other very similar values parsing happily all over the place? It comes down the fact that the Xaml parser only handles a few of the primitive data types namely: bool, int, string and double.  Since the parser has no idea how to convert a string to a float we get the above error. The Solution The sensible solution is “use double not float” but lets not dwell on that, there has to be occasions where such an answer isn’t acceptable. In order to achieve parsing of other types we need an implementation of TypeConverter for the type of the property and then we need to use the TypeConverterAttribute to decorate the property .  As an example the Silverlight SDK provides one for DateTime the DateTimeTypeConverter (yes I know DateTime isn’t really a primitive). The following class will parse in Xaml:- public class MyClass {     [TypeConverter(typeof(DateTimeTypeConverter))]     public DateTime SomeValue {get; set; } } So far though we would need to create a TypeConverter for each primitive type we are using, what if I had the following mad class to support in Xaml:- public class StrangePrimitives {     public Boolean BooleanProp { get; set; }     public Byte ByteProp { get; set; }     public Char CharProp { get; set; }     public DateTime DateTimeProp { get; set; }     public Decimal DecimalProp { get; set; }     public Double DoubleProp { get; set; }     public Int16 Int16Prop { get; set; }     public Int32 Int32Prop { get; set; }     public Int64 Int64Prop { get; set; }     public SByte SByteProp { get; set; }     public Single SingleProp { get; set; }     public String StringProp { get; set; }     public UInt16 UInt16Prop { get; set; }     public UInt32 UInt32Prop { get; set; }     public UInt64 UInt64Prop { get; set; } } Then I want to fill an instance of StrangePrimitives with the following Xaml which of course fails. <local:StrangePrimitives x:Key="MyStrangePrimitives"                          BooleanProp="True"                          ByteProp="156"                          CharProp="A"                          DateTimeProp="06 Jun 2010"                          DecimalProp="123.56"                          DoubleProp="8372.937803"                          Int16Prop="16532"                          Int32Prop="73738248"                          Int64Prop="12345678909298"                          SByteProp="-123"                          SingleProp="39.0"                          StringProp="Hello, World!"                          UInt16Prop="40000"                          UInt32Prop="4294967295"                          UInt64Prop="18446744073709551615"      /> I got to thinking, though, one thing all these primitive types have in common is that they all implement IConvertible so it should be possible to write just one converter to handle them all.  Here it is:- The ConvertibleTypeConverter public class ConvertibleTypeConverter<T> : TypeConverter where T : IConvertible {     public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)     {         return sourceType.GetInterface("IConvertible", false) != null;     }     public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)     {         return destinationType.GetInterface("IConvertible", false) != null;     }     public override object ConvertFrom(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)     {         return ((IConvertible)value).ToType(typeof(T), culture);     }     public override object ConvertTo(ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)     {         return ((IConvertible)value).ToType(destinationType, culture);     } } I won’t bore you with an explanation of how it works, it simply adapts one existing interface (the IConvertible) and exposes it as another (the TypeConverter).   With that in place the previous strange primitives class can be modified as:- public class StrangePrimitives {     public Boolean BooleanProp { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<Byte>))]     public Byte ByteProp { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<Char>))]     public Char CharProp { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<DateTime>))]     public DateTime DateTimeProp { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<Decimal>))]     public Decimal DecimalProp { get; set; }     public Double DoubleProp {get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<Int16>))]     public Int16 Int16Prop { get; set; }     public Int32 Int32Prop { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<Int64>))]     public Int64 Int64Prop { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<SByte>))]     public SByte SByteProp { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<Single>))]     public Single SingleProp { get; set; }     public String StringProp { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<UInt16>))]     public UInt16 UInt16Prop { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<UInt32>))]     public UInt32 UInt32Prop { get; set; }     [TypeConverter(typeof(ConvertibleTypeConverter<UInt64>))]     public UInt64 UInt64Prop { get; set; } } This results in the previous Xaml parsing happily.  Now it seems such an obvious thing to do that one may wonder why such a class doesn’t already existing in Silverlight or at least in the SDK.   I would not be surprised if there were some very good reasons hence use the ConvertibleTypeConverter with caution.  It does seem to me to be a useful little class to have lying around in the toolbox for the odd occasion where it may be needed.

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• To SYNC or not to SYNC – Part 3

  - by AshishRay

  I can't believe it has been almost a year since my last blog post. I know, that's an absolute no-no in the blogosphere. And I know that "I have been busy" is not a good excuse. So - without trying to come up with an excuse - let me state this - my apologies for taking such a long time to write the next Part. Without further ado, here goes. This is Part 3 of a multi-part blog article where we are discussing various aspects of setting up Data Guard synchronous redo transport (SYNC). In Part 1 of this article, I debunked the myth that Data Guard SYNC is similar to a two-phase commit operation. In Part 2, I discussed the various ways that network latency may or may not impact a Data Guard SYNC configuration. In this article, I will talk in details regarding why Data Guard SYNC is a good thing. I will also talk about distance implications for setting up such a configuration. So, Why Good? Why is Data Guard SYNC a good thing? Because, at the end of the day, this gives you the assurance of zero data loss - it doesn’t matter what outage may befall your primary system. Befall! Boy, that sounds theatrical. But seriously - think about this - it minimizes your data risks. That’s a big deal. Whether you have an outage due to bad disks, faulty hardware components, hardware / software bugs, physical data corruptions, power failures, lightning that takes out significant part of your data center, fire that melts your assets, water leakage from the cooling system, human errors such as accidental deletion of online redo log files - it doesn’t matter - you can have that “Om - peace” look on your face and then you can failover to the standby system, without losing a single bit of data in your Oracle database. You will be a hero, as shown in this not so imaginary conversation: IT Manager: Well, what’s the status? You: John is doing the trace analysis on the storage array. IT Manager: So? How long is that gonna take? You: Well, he is stuck, waiting for a response from <insert your not-so-favorite storage vendor here>. IT Manager: So, no root cause yet? You: I told you, he is stuck. We have escalated with their Support, but you know how long these things take. IT Manager: Darn it - the site is down! You: Not really … IT Manager: What do you mean? You: John is stuck, but Sreeni has already done a failover to the Data Guard standby. IT Manager: Whoa, whoa - wait! Failover means we lost some data, why did you do this without letting the Business group know? You: We didn’t lose any data. Remember, we had set up Data Guard with SYNC? So now, any problems on the production – we just failover. No data loss, and we are up and running in minutes. The Business guys don’t need to know. IT Manager: Wow! Are we great or what!! You: I guess … Ok, so you get it - SYNC is good. But as my dear friend Larry Carpenter says, “TANSTAAFL”, or "There ain't no such thing as a free lunch". Yes, of course - investing in Data Guard SYNC means that you have to invest in a low-latency network, you have to monitor your applications and database especially in peak load conditions, and you cannot under-provision your standby systems. But all these are good and necessary things, if you are supporting mission-critical apps that are supposed to be running 24x7. The peace of mind that this investment will give you is priceless, especially if you are serious about HA. How Far Can We Go? Someone may say at this point - well, I can’t use Data Guard SYNC over my coast-to-coast deployment. Most likely - true. So how far can you go? Well, we have customers who have deployed Data Guard SYNC over 300+ miles! Does this mean that you can also deploy over similar distances? Duh - no! I am going to say something here that most IT managers don’t like to hear - “It depends!” It depends on your application design, application response time / throughput requirements, network topology, etc. However, because of the optimal way we do SYNC, customers have been able to stretch Data Guard SYNC deployments over longer distances compared to traditional, storage-centric ways of doing this. The MAA Database 10.2 best practices paper Data Guard Redo Transport & Network Configuration, and Oracle Database 11.2 High Availability Best Practices Manual talk about some of these SYNC-related metrics. For example, a test deployment of Data Guard SYNC over 330 miles with 10ms latency showed an impact less than 5% for a busy OLTP application. Even if you can’t deploy Data Guard SYNC over your WAN distance, or if you already have an ASYNC standby located 1000-s of miles away, here’s another nifty way to boost your HA. Have a local standby, configured SYNC. How local is “local”? Again - it depends. One customer runs a local SYNC standby across the campus. Another customer runs it across 15 miles in another data center. Both of these customers are running Data Guard SYNC as their HA standard. If a localized outage affects their primary system, no problem! They have all the data available on the standby, to which they can failover. Very fast. In seconds. Wait - did I say “seconds”? Yes, Virginia, there is a Santa Claus. But you have to wait till the next blog article to find out more. I assure you tho’ that this time you won’t have to wait for another year for this.

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• Feedback on meeting of the Linux User Group of Mauritius

  Once upon a time in a country far far away... Okay, actually it's not that bad but it has been a while since the last meeting of the Linux User Group of Mauritius (LUGM). There have been plans in the past but it never really happened. Finally, Selven took the opportunity and organised a new meetup with low administrative overhead, proper scheduling on alternative dates and a small attendee's survey on the preferred option. All the pre-work was nicely executed. First, I wasn't sure whether it would be possible to attend. Luckily I got some additional information, like children should come, too, and I was sold to this community gathering. According to other long-term members of the LUGM it was the first time 'ever' that a gathering was organised outside of Quatre Bornes, and I have to admit it was great! LUGM - user group meeting on the 15.06.2013 in L'Escalier Quick overview of Linux & the LUGM With a little bit of delay the LUGM meeting officially started with a quick overview and introduction to Linux presented by Avinash. During the session he told the audience that there had been quite some activity over the island some years ago but unfortunately it had been quiet during recent times. Of course, we also spoke about the acknowledged world dominance of Linux - thanks to Android - and the interesting possibilities for countries like Mauritius. It is known that a couple of public institutions have there back-end infrastructure running on Red Hat Linux systems but the presence on the desktop is still very low. Users are simply hanging on to Windows XP and older versions of Microsoft Office. Following the introduction of the LUGM Ajay joined into the session and it quickly changed into a panel discussion with lots of interesting questions and answers, sharing of first-hand experience either on the job or in private use of Linux, and a couple of ideas about how the LUGM could promote Linux a bit more in Mauritius. It was great to get an insight into other attendee's opinion and activities. Especially taking into consideration that I'm already using Linux since around 1996/97. Frankly speaking, I bought a SuSE 4.x distribution back in those days because I couldn't achieve certain tasks on Windows NT 4.0 without spending a fortune. OpenELEC Mediacenter Next, Selven gave us decent introduction on OpenELEC: Open Embedded Linux Entertainment Center (OpenELEC) is a small Linux distribution built from scratch as a platform to turn your computer into an XBMC media center. OpenELEC is designed to make your system boot fast, and the install is so easy that anyone can turn a blank PC into a media machine in less than 15 minutes. I didn't know about it until this presentation. In the past, I was mainly attached to Video Disk Recorder (VDR) as it allows the use of satellite receiver cards very easily. Hm, somehow I'm still missing my precious HTPC that I had to leave back in Germany years ago. It was great piece of hardware and software; self-built PC in a standard HiFi-sized (43cm) black desktop casing with 2 full-featured Hauppauge DVB-s cards, an old-fashioned Voodoo graphics card, WiFi card, Pioneer slot-in DVD drive, and fully remote controlled via infra-red thanks to Debian, VDR and LIRC. With EP Guide, scheduled recordings and general multimedia centre it offered all the necessary comfort in the living room, besides a Nintendo game console; actually a GameCube at that time... But I have to admit that putting OpenELEC on a Raspberry Pi would be a cool DIY project in the near future. LUGM - our next generation of linux users (15.06.2013) Project Evil Genius (PEG) Don't be scared of the paragraph header. Ish gave us a cool explanation why he named it PEG - Project Evil Genius; it's because of the time of the day when he was scripting down his ideas to be able to build, package and provide software applications to various Linux distributions. The main influence came from openSuSE but the platform didn't cater for his needs and ideas, so he started to work out something on his own. During his passionate session he also talked about the amazing experience he had due to other Linux users from all over the world. During the next couple of days Ish promised to put his script to GitHub... Looking forward to that. Check out Ish's personal blog over at hacklog.in. Highly recommended to read. Why India? Simply because the registration fees per year for an Indian domain are approximately 20 times less than for a Mauritian domain (.mu). Exploring the beach of L'Escalier af the meeting 'After-party' at the beach of L'Escalier Puh, after such interesting sessions, ideas around Linux and good conversation during the breaks and over lunch it was time for a little break-out. Selven suggested that we all should head down to the beach of L'Escalier and get some impressions of nature down here in the south of the island. Talking about 'beach' ;-) - absolutely not comparable to the white-sanded ones here in Flic en Flac... There are no lagoons down at the south coast of Mauriitus, and watching the breaking waves is a different experience and joy after all. Unfortunately, I was a little bit worried about the thoughtless littering at such a remote location. You have to drive on natural paths through the sugar cane fields and I was really shocked by the amount of rubbish lying around almost everywhere. Sad, really sad and it concurs with Yasir's recent article on the same topic. Resumé & outlook It was a great event. I met with new people, had some good conversations, and even my children enjoyed themselves the whole day. The location was well-chosen, enough space for each and everyone, parking spaces and even a playground for the children. Also, a big "Thank You" to Selven and his helpers for the organisation and preparation of lunch. I'm kind of sure that this was an exceptional meeting of LUGM and I'm really looking forward to the next gathering of Linux geeks. Hopefully, soon. All images are courtesy of Avinash Meetoo. More pictures are available on Flickr.

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• Metrics - A little knowledge can be a dangerous thing (or 'Why you're not clever enough to interpret metrics data')

  - by Jason Crease

  At RedGate Software, I work on a .NET obfuscator  called SmartAssembly.  Various features of it use a database to store various things (exception reports, name-mappings, etc.) The user is given the option of using either a SQL-Server database (which requires them to have Microsoft SQL Server), or a Microsoft Access MDB file (which requires nothing). MDB is the default option, but power-users soon switch to using a SQL Server database because it offers better performance and data-sharing. In the fashionable spirit of optimization and metrics, an obvious product-management question is 'Which is the most popular? SQL Server or MDB?' We've collected data about this fact, using our 'Feature-Usage-Reporting' technology (available as part of SmartAssembly) and more recently our 'Application Metrics' technology: Parameter Number of users % of total users Number of sessions Number of usages SQL Server 28 19.0 8115 8115 MDB 114 77.6 1449 1449 (As a disclaimer, please note than SmartAssembly has far more than 132 users . This data is just a selection of one build) So, it would appear that SQL-Server is used by fewer users, but more often. Great. But here's why these numbers are useless to me: Only the original developers understand the data What does a single 'usage' of 'MDB' mean? Does this happen once per run? Once per option change? On clicking the 'Obfuscate Now' button? When running the command-line version or just from the UI version? Each question could skew the data 10-fold either way, and the answers only known by the developer that instrumented the application in the first place. In other words, only the original developer can interpret the data - product-managers cannot interpret the data unaided. Most of the data is from uninterested users About half of people who download and run a free-trial from the internet quit it almost immediately. Only a small fraction use it sufficiently to make informed choices. Since the MDB option is the default one, we don't know how many of those 114 were people CHOOSING to use the MDB, or how many were JUST HAPPENING to use this MDB default for their 20-second trial. This is a problem we see across all our metrics: Are people are using X because it's the default or are they using X because they want to use X? We need to segment the data further - asking what percentage of each percentage meet our criteria for an 'established user' or 'informed user'. You end up spending hours writing sophisticated and dubious SQL queries to segment the data further. Not fun. You can't find out why they used this feature Metrics can answer the when and what, but not the why. Why did people use feature X? If you're anything like me, you often click on random buttons in unfamiliar applications just to explore the feature-set. If we listened uncritically to metrics at RedGate, we would eliminate the most-important and more-complex features which people actually buy the software for, leaving just big buttons on the main page and the About-Box. "Ah, that's interesting!" rather than "Ah, that's actionable!" People do love data. Did you know you eat 1201 chickens in a lifetime? But just 4 cows? Interesting, but useless. Often metrics give you a nice number: '5.8% of users have 3 or more monitors' . But unless the statistic is both SUPRISING and ACTIONABLE, it's useless. Most metrics are collected, reviewed with lots of cooing. and then forgotten. Unless a piece-of-data could change things, it's useless collecting it. People get obsessed with significance levels The first things that lots of people do with this data is do a t-test to get a significance level ("Hey! We know with 99.64% confidence that people prefer SQL Server to MDBs!") Believe me: other causes of error/misinterpretation in your data are FAR more significant than your t-test could ever comprehend. Confirmation bias prevents objectivity If the data appears to match our instinct, we feel satisfied and move on. If it doesn't, we suspect the data and dig deeper, plummeting down a rabbit-hole of segmentation and filtering until we give-up and move-on. Data is only useful if it can change our preconceptions. Do you trust this dodgy data more than your own understanding, knowledge and intelligence?  I don't. There's always multiple plausible ways to interpret/action any data Let's say we segment the above data, and get this data: Post-trial users (i.e. those using a paid version after the 14-day free-trial is over): Parameter Number of users % of total users Number of sessions Number of usages SQL Server 13 9.0 1115 1115 MDB 5 4.2 449 449 Trial users: Parameter Number of users % of total users Number of sessions Number of usages SQL Server 15 10.0 7000 7000 MDB 114 77.6 1000 1000 How do you interpret this data? It's one of: Mostly SQL Server users buy our software. People who can't afford SQL Server tend to be unable to afford or unwilling to buy our software. Therefore, ditch MDB-support. Our MDB support is so poor and buggy that our massive MDB user-base doesn't buy it.  Therefore, spend loads of money improving it, and think about ditching SQL-Server support. People 'graduate' naturally from MDB to SQL Server as they use the software more. Things are fine the way they are. We're marketing the tool wrong. The large number of MDB users represent uninformed downloaders. Tell marketing to aggressively target SQL Server users. To choose an interpretation you need to segment again. And again. And again, and again. Opting-out is correlated with feature-usage Metrics tends to be opt-in. This skews the data even further. Between 5% and 30% of people choose to opt-in to metrics (often called 'customer improvement program' or something like that). Casual trial-users who are uninterested in your product or company are less likely to opt-in. This group is probably also likely to be MDB users. How much does this skew your data by? Who knows? It's not all doom and gloom. There are some things metrics can answer well. Environment facts. How many people have 3 monitors? Have Windows 7? Have .NET 4 installed? Have Japanese Windows? Minor optimizations.  Is the text-box big enough for average user-input? Performance data. How long does our app take to start? How many databases does the average user have on their server? As you can see, questions about who-the-user-is rather than what-the-user-does are easier to answer and action. Conclusion Use SmartAssembly. If not for the metrics (called 'Feature-Usage-Reporting'), then at least for the obfuscation/error-reporting. Data raises more questions than it answers. Questions about environment are the easiest to answer.

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• How to implement smooth flocking

  - by Craig

  I'm working on a simple survival game, avoid the big guy and chase the the small guys to stay alive for as long as possible. I have taken the chase and evade example from MSDN create and drawn 20 mice on the screen. I want the small guys to flock when they arent evading. They are doing this, but it isnt as smooth as I would like it to be. How do i make the movement smoother? Its very jittery.# Below is what I have going at the moment, flocking code is within the IF statement, when it isnt set to evading. Any help would be greatly appreciated! :) namespace ChaseAndEvade { class MouseSprite { public enum MouseAiState { // evading the cat Evading, // the mouse can't see the "cat", and it's wandering around. Wander } // how fast can the mouse move? public float MaxMouseSpeed = 4.5f; // and how fast can it turn? public float MouseTurnSpeed = 0.20f; // MouseEvadeDistance controls the distance at which the mouse will flee from // cat. If the mouse is further than "MouseEvadeDistance" pixels away, he will // consider himself safe. public float MouseEvadeDistance = 100.0f; // this constant is similar to TankHysteresis. The value is larger than the // tank's hysteresis value because the mouse is faster than the tank: with a // higher velocity, small fluctuations are much more visible. public float MouseHysteresis = 60.0f; public Texture2D mouseTexture; public Vector2 mouseTextureCenter; public Vector2 mousePosition; public MouseAiState mouseState = MouseAiState.Wander; public float mouseOrientation; public Vector2 mouseWanderDirection; int separationImpact = 4; int cohesionImpact = 6; int alignmentImpact = 2; int sensorDistance = 50; public void UpdateMouse(Vector2 position, MouseSprite [] mice, int numberMice, int index) { Vector2 catPosition = position; int enemies = numberMice; // first, calculate how far away the mouse is from the cat, and use that // information to decide how to behave. If they are too close, the mouse // will switch to "active" mode - fleeing. if they are far apart, the mouse // will switch to "idle" mode, where it roams around the screen. // we use a hysteresis constant in the decision making process, as described // in the accompanying doc file. float distanceFromCat = Vector2.Distance(mousePosition, catPosition); // the cat is a safe distance away, so the mouse should idle: if (distanceFromCat > MouseEvadeDistance + MouseHysteresis) { mouseState = MouseAiState.Wander; } // the cat is too close; the mouse should run: else if (distanceFromCat < MouseEvadeDistance - MouseHysteresis) { mouseState = MouseAiState.Evading; } // if neither of those if blocks hit, we are in the "hysteresis" range, // and the mouse will continue doing whatever it is doing now. // the mouse will move at a different speed depending on what state it // is in. when idle it won't move at full speed, but when actively evading // it will move as fast as it can. this variable is used to track which // speed the mouse should be moving. float currentMouseSpeed; // the second step of the Update is to change the mouse's orientation based // on its current state. if (mouseState == MouseAiState.Evading) { // If the mouse is "active," it is trying to evade the cat. The evasion // behavior is accomplished by using the TurnToFace function to turn // towards a point on a straight line facing away from the cat. In other // words, if the cat is point A, and the mouse is point B, the "seek // point" is C. // C // B // A Vector2 seekPosition = 2 * mousePosition - catPosition; // Use the TurnToFace function, which we introduced in the AI Series 1: // Aiming sample, to turn the mouse towards the seekPosition. Now when // the mouse moves forward, it'll be trying to move in a straight line // away from the cat. mouseOrientation = ChaseAndEvadeGame.TurnToFace(mousePosition, seekPosition, mouseOrientation, MouseTurnSpeed); // set currentMouseSpeed to MaxMouseSpeed - the mouse should run as fast // as it can. currentMouseSpeed = MaxMouseSpeed; } else { // if the mouse isn't trying to evade the cat, it should just meander // around the screen. we'll use the Wander function, which the mouse and // tank share, to accomplish this. mouseWanderDirection and // mouseOrientation are passed by ref so that the wander function can // modify them. for more information on ref parameters, see // http://msdn2.microsoft.com/en-us/library/14akc2c7(VS.80).aspx ChaseAndEvadeGame.Wander(mousePosition, ref mouseWanderDirection, ref mouseOrientation, MouseTurnSpeed); // if the mouse is wandering, it should only move at 25% of its maximum // speed. currentMouseSpeed = .25f * MaxMouseSpeed; Vector2 separate = Vector2.Zero; Vector2 moveCloser = Vector2.Zero; Vector2 moveAligned = Vector2.Zero; // What the AI does when it sees other AIs for (int j = 0; j < enemies; j++) { if (index != j) { // Calculate a vector towards another AI Vector2 separation = mice[index].mousePosition - mice[j].mousePosition; // Only react if other AI is within a certain distance if ((separation.Length() < this.sensorDistance) & (separation.Length()> 0) ) { moveAligned += mice[j].mouseWanderDirection; float distance = Math.Abs(separation.Length()); if (distance == 0) distance = 1; moveCloser += mice[j].mousePosition; separation.Normalize(); separate += separation / distance; } } } if (moveAligned.LengthSquared() != 0) { moveAligned.Normalize(); } if (moveCloser.LengthSquared() != 0) { moveCloser.Normalize(); } moveCloser /= enemies; mice[index].mousePosition += (separate * separationImpact) + (moveCloser * cohesionImpact) + (moveAligned * alignmentImpact); } // The final step is to move the mouse forward based on its current // orientation. First, we construct a "heading" vector from the orientation // angle. To do this, we'll use Cosine and Sine to tell us the x and y // components of the heading vector. See the accompanying doc for more // information. Vector2 heading = new Vector2( (float)Math.Cos(mouseOrientation), (float)Math.Sin(mouseOrientation)); // by multiplying the heading and speed, we can get a velocity vector. the // velocity vector is then added to the mouse's current position, moving him // forward. mousePosition += heading * currentMouseSpeed; } } }

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• Struct Method for Loops Problem

  - by Annalyne

  I have tried numerous times how to make a do-while loop using the float constructor for my code but it seems it does not work properly as I wanted. For summary, I am making a TBRPG in C++ and I encountered few problems. But before that, let me post my code. #include <iostream> #include <string> #include <ctime> #include <cstdlib> using namespace std; int char_level = 1; //the starting level of the character. string town; //town string town_name; //the name of the town the character is in. string charname; //holds the character's name upon the start of the game int gems = 0; //holds the value of the games the character has. const int MAX_ITEMS = 15; //max items the character can carry string inventory [MAX_ITEMS]; //the inventory of the character in game int itemnum = 0; //number of items that the character has. bool GameOver = false; //boolean intended for the game over scr. string monsterTroop [] = {"Slime", "Zombie", "Imp", "Sahaguin, Hounds, Vampire"}; //monster name float monsterTroopHealth [] = {5.0f, 10.0f, 15.0f, 20.0f, 25.0f}; // the health of the monsters int monLifeBox; //life carrier of the game's enemy troops int enemNumber; //enemy number //inventory[itemnum++] = "Sword"; class RPG_Game_Enemy { public: void enemyAppear () { srand(time(0)); enemNumber = 1+(rand()%3); if (enemNumber == 1) cout << monsterTroop[1]; //monster troop 1 else if (enemNumber == 2) cout << monsterTroop[2]; //monster troop 2 else if (enemNumber == 3) cout << monsterTroop[3]; //monster troop 3 else if (enemNumber == 4) cout << monsterTroop[4]; //monster troop 4 } void enemDefeat () { cout << "The foe has been defeated. You are victorious." << endl; } void enemyDies() { //if the enemy dies: //collapse declaration cout << "The foe vanished and you are victorious!" << endl; } }; class RPG_Scene_Battle { public: RPG_Scene_Battle(float ini_health) : health (ini_health){}; float getHealth() { return health; } void setHealth(float rpg_val){ health = rpg_val;}; private: float health; }; //---------------------------------------------------------------// // Conduct Damage for the Scene Battle's Damage //---------------------------------------------------------------// float conductDamage(RPG_Scene_Battle rpg_tr, float damage) { rpg_tr.setHealth(rpg_tr.getHealth() - damage); return rpg_tr.getHealth(); }; // ------------------------------------------------------------- // void RPG_Scene_DisplayItem () { cout << "Items: \n"; for (int i=0; i < itemnum; ++i) cout << inventory[i] <<endl; }; In this code I have so far, the problem I have is the battle scene. For example, the player battles a Ghost with 10 HP, when I use a do while loop to subtract the HP of the character and the enemy, it only deducts once in the do while. Some people said I should use a struct, but I have no idea how to make it. Is there a way someone can display a code how to implement it on my game? Edit: I made the do-while by far like this: do RPG_Scene_Battle (player, 20.0f); RPG_Scene_Battle (enemy, 10.0f); cout << "Battle starts!" <<endl; cout << "You used a blade skill and deducted 2 hit points to the enemy!" conductDamage (enemy, 2.0f); while (enemy!=0) also, I made something like this: #include <iostream> using namespace std; int gems = 0; class Entity { public: Entity(float startingHealth) : health(startingHealth){}; // initialize health float getHealth(){return health;} void setHealth(float value){ health = value;}; private: float health; }; float subtractHealthFrom(Entity& ent, float damage) { ent.setHealth(ent.getHealth() - damage); return ent.getHealth(); }; int main () { Entity character(10.0f); Entity enemy(10.0f); cout << "Hero Life: "; cout << subtractHealthFrom(character, 2.0f) <<endl; cout << "Monster Life: "; cout << subtractHealthFrom(enemy, 2.0f) <<endl; cout << "Hero Life: "; cout << subtractHealthFrom(character, 2.0f) <<endl; cout << "Monster Life: "; cout << subtractHealthFrom(enemy, 2.0f) <<endl; }; Struct method, they say, should solve this problem. How can I continously deduct hp from the enemy? Whenever I deduct something, it would return to its original value -_-

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• Globe SSL with NGINX SSL certificate problem, please help

  - by PartySoft

  I have a big problem with installing a certificat for nginx (same happends with apache though) I have 3 files __domain_com.crt __domain_com.ca-bundle and ssl.key. I tried to append cat __domain_com.crt __leechpack_com.ca-bundle bundle.crt but if I do it like this i get an error: [emerg]: SSL_CTX_use_certificate_chain_file("/etc/nginx/__leechpack_com.crt") failed (SSL: error:0906D066:PEM routines:PEM_read_bio:bad end line error:140DC009:SSL routines:SSL_CTX_use_certificate_chain_file:PEM lib) And that's because the delimiters of the certificates arren't separated. ZqTjb+WBJQ== -----END CERTIFICATE----------BEGIN CERTIFICATE----- MIIE6DCCA9CgAwIBAgIQdIYhlpUQySkmKUvMi/gpLDANBgkqhkiG9w0BAQUFADBv If i separate them with an enter between certificated it will at least start but i will get the same warning from Firefox: This Connection is Untrusted You have asked Firefox to connect securely to domain.com, but we can't confirm that your connection is secure. The concatenate solution it is given by Globe SSL and the NGINX site but it doesn't work. I think the bundle is ignored though. http://customer.globessl.com/knowledgebase/55/Certificate-Installation--Nginx.html http://nginx.org/en/docs/http/configuring_https_servers.html#chains%20http://wiki.nginx.org/NginxHttpSslModule if i do openssl s_client -connect down.leechpack.com:443 CONNECTED(00000003) depth=0 /OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com verify error:num=20:unable to get local issuer certificate verify return:1 depth=0 /OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com verify error:num=27:certificate not trusted verify return:1 depth=0 /OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com verify error:num=21:unable to verify the first certificate verify return:1 --- Certificate chain 0 s:/OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com i:/C=RO/O=GLOBE HOSTING CERTIFICATION AUTHORITY/CN=GLOBE SSL Domain Validated CA 1 s:/C=US/O=Globe Hosting, Inc./OU=GlobeSSL DV Certification Authority/CN=GlobeSSL CA i:/C=SE/O=AddTrust AB/OU=AddTrust External TTP Network/CN=AddTrust External CA Root --- Server certificate -----BEGIN CERTIFICATE----- MIIFQzCCBCugAwIBAgIQRnpCmtwX7z7GTla0QktE6DANBgkqhkiG9w0BAQUFADBl MQswCQYDVQQGEwJSTzEuMCwGA1UEChMlR0xPQkUgSE9TVElORyBDRVJUSUZJQ0FU SU9OIEFVVEhPUklUWTEmMCQGA1UEAxMdR0xPQkUgU1NMIERvbWFpbiBWYWxpZGF0 ZWQgQ0EwHhcNMTAwMjExMDAwMDAwWhcNMTEwMjExMjM1OTU5WjCBjTEhMB8GA1UE CxMYRG9tYWluIENvbnRyb2wgVmFsaWRhdGVkMSgwJgYDVQQLEx9Qcm92aWRlZCBi eSBHbG9iZSBIb3N0aW5nLCBJbmMuMSQwIgYDVQQLExtHbG9iZSBTdGFuZGFyZCBX aWxkY2FyZCBTU0wxGDAWBgNVBAMUDyoubGVlY2hwYWNrLmNvbTCCASIwDQYJKoZI hvcNAQEBBQADggEPADCCAQoCggEBAKX7jECMlYEtcvqVWQVUpXNxO/VaHELghqy/ Ml8dOfOXG29ZMZsKUMqS0jXEwd+Bdpm31lBxOALkj8o79hX0tspLMjgtCnreaker 49y62BcjfguXRFAaiseXTNbMer5lDWiHlf1E7uCoTTiczGqBNfl6qSJlpe4rYBtq XxBAiygaNba6Owghuh19+Uj8EICb2pxbJNFfNzU1D9InFdZSVqKHYBem4Cdrtxua W4+YONsfLnnfkRQ6LOLeYExHziTQhSavSv9XaCl9Zqzm5/eWbQqLGRpSJoEPY/0T GqnmeMIq5M35SWZgOVV10j3pOCS8o0zpp7hMJd2R/HwVaPCLjukCAwEAAaOCAcQw ggHAMB8GA1UdIwQYMBaAFB9UlnKtPUDnlln3STFTCWb5DWtyMB0GA1UdDgQWBBT0 8rPIMr7JDa2Xs5he5VXAvMWArjAOBgNVHQ8BAf8EBAMCBaAwDAYDVR0TAQH/BAIw ADAdBgNVHSUEFjAUBggrBgEFBQcDAQYIKwYBBQUHAwIwVQYDVR0gBE4wTDBKBgsr BgEEAbIxAQICGzA7MDkGCCsGAQUFBwIBFi1odHRwOi8vd3d3Lmdsb2Jlc3NsLmNv bS9kb2NzL0dsb2JlU1NMX0NQUy5wZGYwRgYDVR0fBD8wPTA7oDmgN4Y1aHR0cDov L2NybC5nbG9iZXNzbC5jb20vR0xPQkVTU0xEb21haW5WYWxpZGF0ZWRDQS5jcmww dwYIKwYBBQUHAQEEazBpMEEGCCsGAQUFBzAChjVodHRwOi8vY3J0Lmdsb2Jlc3Ns LmNvbS9HTE9CRVNTTERvbWFpblZhbGlkYXRlZENBLmNydDAkBggrBgEFBQcwAYYY aHR0cDovL29jc3AuZ2xvYmVzc2wuY29tMCkGA1UdEQQiMCCCDyoubGVlY2hwYWNr LmNvbYINbGVlY2hwYWNrLmNvbTANBgkqhkiG9w0BAQUFAAOCAQEAB2Y7vQsq065K s+/n6nJ8ZjOKbRSPEiSuFO+P7ovlfq9OLaWRHUtJX0sLntnWY1T9hVPvS5xz/Ffl w9B8g/EVvvfMyOw/5vIyvHq722fAAC1lWU1rV3ww0ng5bgvD20AgOlIaYBvRq8EI 5Dxo2og2T1UjDN44GOSWsw5jetvVQ+SPeNPQLWZJS9pNCzFQ/3QDWNPOvHqEeRcz WkOTCqbOSZYvoSPvZ3APh+1W6nqiyoku/FCv9otSCtXPKtyVa23hBQ+iuxqIM4/R gncnUKASi6KQrWMQiAI5UDCtq1c09uzjw+JaEzAznxEgqftTOmXAJSQGqZGd6HpD ZqTjb+WBJQ== -----END CERTIFICATE----- subject=/OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com issuer=/C=RO/O=GLOBE HOSTING CERTIFICATION AUTHORITY/CN=GLOBE SSL Domain Validated CA --- No client certificate CA names sent --- SSL handshake has read 3313 bytes and written 343 bytes --- New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-SHA Server public key is 2048 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE SSL-Session: Protocol : TLSv1 Cipher : DHE-RSA-AES256-SHA Session-ID: 5F9C8DC277A372E28A4684BAE5B311533AD30E251369D144A13DECA3078E067F Session-ID-ctx: Master-Key: 9B531A75347E6E7D19D95365C1208F2ED37E4004AA8F71FC614A18937BEE2ED9F82D58925E0B3931492AD3D2AA6EFD3B Key-Arg : None Start Time: 1288618211 Timeout : 300 (sec) Verify return code: 21 (unable to verify the first certificate) ---

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• Globe SSL with NGINX SSL certificate problem, please help

  - by PartySoft

  Hello, I have a big problem with installing a certificat for nginx (same happends with apache though) I have 3 files __domain_com.crt __domain_com.ca-bundle and ssl.key. I tried to append cat __domain_com.crt __leechpack_com.ca-bundle bundle.crt but if I do it like this i get an error: [emerg]: SSL_CTX_use_certificate_chain_file("/etc/nginx/__leechpack_com.crt") failed (SSL: error:0906D066:PEM routines:PEM_read_bio:bad end line error:140DC009:SSL routines:SSL_CTX_use_certificate_chain_file:PEM lib) And that's because the delimiters of the certificates arren't separated. ZqTjb+WBJQ== -----END CERTIFICATE----------BEGIN CERTIFICATE----- MIIE6DCCA9CgAwIBAgIQdIYhlpUQySkmKUvMi/gpLDANBgkqhkiG9w0BAQUFADBv If i separate them with an enter between certificated it will at least start but i will get the same warning from Firefox: This Connection is Untrusted You have asked Firefox to connect securely to domain.com, but we can't confirm that your connection is secure. The concatenate solution it is given by Globe SSL and the NGINX site but it doesn't work. I think the bundle is ignored though. http://customer.globessl.com/knowledgebase/55/Certificate-Installation--Nginx.html http://nginx.org/en/docs/http/configuring_https_servers.html#chains%20http://wiki.nginx.org/NginxHttpSslModule if i do openssl s_client -connect down.leechpack.com:443 CONNECTED(00000003) depth=0 /OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com verify error:num=20:unable to get local issuer certificate verify return:1 depth=0 /OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com verify error:num=27:certificate not trusted verify return:1 depth=0 /OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com verify error:num=21:unable to verify the first certificate verify return:1 --- Certificate chain 0 s:/OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com i:/C=RO/O=GLOBE HOSTING CERTIFICATION AUTHORITY/CN=GLOBE SSL Domain Validated CA 1 s:/C=US/O=Globe Hosting, Inc./OU=GlobeSSL DV Certification Authority/CN=GlobeSSL CA i:/C=SE/O=AddTrust AB/OU=AddTrust External TTP Network/CN=AddTrust External CA Root --- Server certificate -----BEGIN CERTIFICATE----- MIIFQzCCBCugAwIBAgIQRnpCmtwX7z7GTla0QktE6DANBgkqhkiG9w0BAQUFADBl MQswCQYDVQQGEwJSTzEuMCwGA1UEChMlR0xPQkUgSE9TVElORyBDRVJUSUZJQ0FU SU9OIEFVVEhPUklUWTEmMCQGA1UEAxMdR0xPQkUgU1NMIERvbWFpbiBWYWxpZGF0 ZWQgQ0EwHhcNMTAwMjExMDAwMDAwWhcNMTEwMjExMjM1OTU5WjCBjTEhMB8GA1UE CxMYRG9tYWluIENvbnRyb2wgVmFsaWRhdGVkMSgwJgYDVQQLEx9Qcm92aWRlZCBi eSBHbG9iZSBIb3N0aW5nLCBJbmMuMSQwIgYDVQQLExtHbG9iZSBTdGFuZGFyZCBX aWxkY2FyZCBTU0wxGDAWBgNVBAMUDyoubGVlY2hwYWNrLmNvbTCCASIwDQYJKoZI hvcNAQEBBQADggEPADCCAQoCggEBAKX7jECMlYEtcvqVWQVUpXNxO/VaHELghqy/ Ml8dOfOXG29ZMZsKUMqS0jXEwd+Bdpm31lBxOALkj8o79hX0tspLMjgtCnreaker 49y62BcjfguXRFAaiseXTNbMer5lDWiHlf1E7uCoTTiczGqBNfl6qSJlpe4rYBtq XxBAiygaNba6Owghuh19+Uj8EICb2pxbJNFfNzU1D9InFdZSVqKHYBem4Cdrtxua W4+YONsfLnnfkRQ6LOLeYExHziTQhSavSv9XaCl9Zqzm5/eWbQqLGRpSJoEPY/0T GqnmeMIq5M35SWZgOVV10j3pOCS8o0zpp7hMJd2R/HwVaPCLjukCAwEAAaOCAcQw ggHAMB8GA1UdIwQYMBaAFB9UlnKtPUDnlln3STFTCWb5DWtyMB0GA1UdDgQWBBT0 8rPIMr7JDa2Xs5he5VXAvMWArjAOBgNVHQ8BAf8EBAMCBaAwDAYDVR0TAQH/BAIw ADAdBgNVHSUEFjAUBggrBgEFBQcDAQYIKwYBBQUHAwIwVQYDVR0gBE4wTDBKBgsr BgEEAbIxAQICGzA7MDkGCCsGAQUFBwIBFi1odHRwOi8vd3d3Lmdsb2Jlc3NsLmNv bS9kb2NzL0dsb2JlU1NMX0NQUy5wZGYwRgYDVR0fBD8wPTA7oDmgN4Y1aHR0cDov L2NybC5nbG9iZXNzbC5jb20vR0xPQkVTU0xEb21haW5WYWxpZGF0ZWRDQS5jcmww dwYIKwYBBQUHAQEEazBpMEEGCCsGAQUFBzAChjVodHRwOi8vY3J0Lmdsb2Jlc3Ns LmNvbS9HTE9CRVNTTERvbWFpblZhbGlkYXRlZENBLmNydDAkBggrBgEFBQcwAYYY aHR0cDovL29jc3AuZ2xvYmVzc2wuY29tMCkGA1UdEQQiMCCCDyoubGVlY2hwYWNr LmNvbYINbGVlY2hwYWNrLmNvbTANBgkqhkiG9w0BAQUFAAOCAQEAB2Y7vQsq065K s+/n6nJ8ZjOKbRSPEiSuFO+P7ovlfq9OLaWRHUtJX0sLntnWY1T9hVPvS5xz/Ffl w9B8g/EVvvfMyOw/5vIyvHq722fAAC1lWU1rV3ww0ng5bgvD20AgOlIaYBvRq8EI 5Dxo2og2T1UjDN44GOSWsw5jetvVQ+SPeNPQLWZJS9pNCzFQ/3QDWNPOvHqEeRcz WkOTCqbOSZYvoSPvZ3APh+1W6nqiyoku/FCv9otSCtXPKtyVa23hBQ+iuxqIM4/R gncnUKASi6KQrWMQiAI5UDCtq1c09uzjw+JaEzAznxEgqftTOmXAJSQGqZGd6HpD ZqTjb+WBJQ== -----END CERTIFICATE----- subject=/OU=Domain Control Validated/OU=Provided by Globe Hosting, Inc./OU=Globe Standard Wildcard SSL/CN=*.domain.com issuer=/C=RO/O=GLOBE HOSTING CERTIFICATION AUTHORITY/CN=GLOBE SSL Domain Validated CA --- No client certificate CA names sent --- SSL handshake has read 3313 bytes and written 343 bytes --- New, TLSv1/SSLv3, Cipher is DHE-RSA-AES256-SHA Server public key is 2048 bit Secure Renegotiation IS supported Compression: NONE Expansion: NONE SSL-Session: Protocol : TLSv1 Cipher : DHE-RSA-AES256-SHA Session-ID: 5F9C8DC277A372E28A4684BAE5B311533AD30E251369D144A13DECA3078E067F Session-ID-ctx: Master-Key: 9B531A75347E6E7D19D95365C1208F2ED37E4004AA8F71FC614A18937BEE2ED9F82D58925E0B3931492AD3D2AA6EFD3B Key-Arg : None Start Time: 1288618211 Timeout : 300 (sec) Verify return code: 21 (unable to verify the first certificate) ---

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• configure squid3 to set up a web proxy in ubuntu12.04

  - by Gnijuohz

  I am in a LAN and have to use a proxy given to access the web in a very limited way. I can't even use google, github.com or SE sites. However I can use ssh to log into a server, which I have root access so basically I can do anything I want with it. So I was thinking that maybe I could use that server as a proxy so I can visit sites through it. I tested it using ssh -vT [email protected] which gave a proper response. And In my computer I can't do this. Also I tried downloading something from the gun.org using wget, which can't be done in my computer too. And it succeeded on that server. I don't know if that's enough to say that this server have full access to the Internet. But I assumed so and I installed squid3 on it. After trying some while, I failed to get it working. I got this after I run squid3 -k parse 2012/07/06 21:45:18| Processing Configuration File: /etc/squid3/squid.conf (depth 0) 2012/07/06 21:45:18| Processing: acl manager proto cache_object 2012/07/06 21:45:18| Processing: acl localhost src 127.0.0.1/32 ::1 2012/07/06 21:45:18| Processing: acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1 2012/07/06 21:45:18| Processing: acl localnet src 10.1.0.0/16 # RFC1918 possible internal network 2012/07/06 21:45:18| Processing: acl SSL_ports port 443 2012/07/06 21:45:18| Processing: acl Safe_ports port 80 # http 2012/07/06 21:45:18| Processing: acl Safe_ports port 21 # ftp 2012/07/06 21:45:18| Processing: acl Safe_ports port 443 # https 2012/07/06 21:45:18| Processing: acl Safe_ports port 70 # gopher 2012/07/06 21:45:18| Processing: acl Safe_ports port 210 # wais 2012/07/06 21:45:18| Processing: acl Safe_ports port 1025-65535 # unregistered ports 2012/07/06 21:45:18| Processing: acl Safe_ports port 280 # http-mgmt 2012/07/06 21:45:18| Processing: acl Safe_ports port 488 # gss-http 2012/07/06 21:45:18| Processing: acl Safe_ports port 591 # filemaker 2012/07/06 21:45:18| Processing: acl Safe_ports port 777 # multiling http 2012/07/06 21:45:18| Processing: acl CONNECT method CONNECT 2012/07/06 21:45:18| Processing: http_port 3128 transparent vhost vport 2012/07/06 21:45:18| Starting Authentication on port [::]:3128 2012/07/06 21:45:18| Disabling Authentication on port [::]:3128 (interception enabled) 2012/07/06 21:45:18| Disabling IPv6 on port [::]:3128 (interception enabled) 2012/07/06 21:45:18| Processing: cache_mem 1000 MB 2012/07/06 21:45:18| Processing: cache_swap_low 90 2012/07/06 21:45:18| Processing: coredump_dir /var/spool/squid3 2012/07/06 21:45:18| Processing: refresh_pattern ^ftp: 1440 20% 10080 2012/07/06 21:45:18| Processing: refresh_pattern ^gopher: 1440 0% 1440 2012/07/06 21:45:18| Processing: refresh_pattern -i (/cgi-bin/|?) 0 0% 0 2012/07/06 21:45:18| Processing: refresh_pattern (Release|Packages(.gz)*)$ 0 20% 2880 2012/07/06 21:45:18| Processing: refresh_pattern . 0 20% 4320 2012/07/06 21:45:18| Processing: ipcache_high 95 2012/07/06 21:45:18| Processing: http_access allow all I deleted some allow and deny rules and added http_access allow all so that all the request would be allowed. After configuring my computer, I got this error: Access control configuration prevents your request from being allowed at this time. Please contact your service provider if you feel this is incorrect. And the log in the server showed that my TCP requests had all been denied. So, first of all, is what I am trying to do achievable? If so, how to configure the squid in the server so that I use it as a proxy to surf the Internet? My computer and the server both run Ubuntu11.04. Thanks for any help~

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• Trouble setting up PATH for Java on Debian

  - by milkmansrevenge

  I am trying to get Oracle Java 7 update 3 working correctly on Debian 6. I have downloaded and set up the files in /usr/java/jre1.7.0_03. I have also set the following two lines at the end of /etc/bash.bashrc: export JAVA_HOME=/usr/java/jre1.7.0_03 export PATH=$PATH:$JAVA_HOME/bin Logging in as other users and root is fine, Java can be found: chris@mc:~$ java -version java version "1.7.0_03" Java(TM) SE Runtime Environment (build 1.7.0_03-b04) Java HotSpot(TM) 64-Bit Server VM (build 22.1-b02, mixed mode) However there are two cases where Java cannot be found as detailed below. Note that both of these worked fine when I have previously installed OpenJDK Java 6 via aptitude, but I need Oracle Java 7 for various reasons. Most importantly, I cannot run commands as another user via su, despite the PATH showing that Java should be present. The user was created with adduser chris root@mc:~# su chris -c "echo $PATH" /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/java/jre1.7.0_03/bin:/bin root@mc:~# su chris -c "java -version" bash: java: command not found root@mc:~# su chris -c "/usr/java/jre1.7.0_03/bin/java -version" java version "1.7.0_03" ... How can it be in the PATH but not be found? Update 05/04/2012: explained by Daniel, to do with it being a non-interactive shell so files such as /etc/profile and /etc/bash.bashrc are not executed. Doing a full swap to that user and running Java works: root@mc:~# su chris chris@mc:/root$ java -version java version "1.7.0_03" ... I run a script on start up which exhibits similar but slightly different problems. The script is located in /etc/init.d/start-mystuff.sh and calls a jar: #!/bin/bash # /etc/init.d/start-mystuff.sh java -jar /opt/Mars.jar I can confirm that the script runs on start up and the exit code is 127, which indicates command not found. Inserting a line to print/save the PATH shows that it is: /sbin:/usr/sbin:/bin:/usr/bin This second problem isn't as important because I can just point directly to the Java executable in the script, but I am still curious! I have tried setting the full PATH and JAVA_HOME explicitly in /etc/environment which didn't help. I have also tried setting them in /etc/profile which doesn't seem to help either. I have tried logging in and out again after setting PATH in the various locations (duh!). Anyway, long post for what will probably have a simple one line solution :( Any help with this would be greatly appreciated, I have spent far too long trying to fix it by myself. Motivation The first problem may seem obscure but in my system I have users that are not allowed SSH access yet I still want to run processes as them. I have a ton of scripts operating in this way and don't want to have to change them all.

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