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• The Niantic Project: Ingress by Felicia Hajra-Lee

  Despite the current fact that the augmented reality game for Android is still in beta phase, it is amazing to see that the world of literature is already taking momentum on this 'real-life' universe. After reading 'The Alignment: Ingress' by Thomas Greanias it took only a blink of the eye to go for 'The Niantic Project: Ingress' by Felicia Hajra-Lee, too. Here is the review I posted on Amazon.com: Ingress, a parallel universe to our reality, is here. There is no doubt about this anymore... The Niantic Project, originated at the CERN collider in Geneva, Switzerland, got into focus of global players. And the game is hard; fair-play is only for the fainted ones. Felicia understands to drag the audience directly into the action of the Niantic Project and its protagonists. The novella is heavily based on the investigations posted daily on the website of Ingress. She really understands how to interweave the various clues and creates an atmosphere where it sometimes feels challenging to differentiate between fiction and reality. It all starts with 'Epiphany Night' at the Niantic Labs, the high exposure of Exotic Matter (XM) and the escape of scientist Dr. Devra Bogdanovich and 'sentinel' Roland Jarvis. Of course, a new research, or should we name it technology, like the Niantic Project has to be protected and there are multiple parties on the hunt. Throughout the various chapters Felicia introduces new potential buyers from all over the globe, gives us detailed insights on the hunters and their brutal effectiveness to finish an assignment, and manages to keep the reader in high-pitched mode thanks to a couple of turn-arounds in the overall story. Personally, I have to say that I really enjoyed reading this title. Felicia's love to details is absolutely amazing, and sometimes I was really wondering whether she would be one of the assassins. But unfortunately I also have to say that I'm not a great fan of the structural organization of the (title-less) chapters. It is fascinating to follow the ventures of Devra, Farlowe and 855 but occasionally I had to go back to previous paragraphs in order to keep track of the individual plots. Overall a great title, captivating and rich in details but simply too short. Please Fecilia, gives us more to read. As an owner of an Android smartphone or tablet, you should get yourself into the world of Ingress. Check out the Play Store to install the app. Now. ;-)

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• Brendan Gregg's "Systems Performance: Enterprise and the Cloud"

  - by user12608550

  Long ago, the prerequisite UNIX performance book was Adrian Cockcroft's 1994 classic, Sun Performance and Tuning: Sparc & Solaris, later updated in 1998 as Java and the Internet. As Solaris evolved to include the invaluable DTrace observability features, new essential performance references have been published, such as Solaris Performance and Tools: DTrace and MDB Techniques for Solaris 10 and OpenSolaris (2006)  by McDougal, Mauro, and Gregg, and DTrace: Dynamic Tracing in Oracle Solaris, Mac OS X and FreeBSD (2011), also by Mauro and Gregg. Much has occurred in Solaris Land since those books appeared, notably Oracle's acquisition of Sun Microsystems in 2010 and the demise of the OpenSolaris community. But operating system technologies have continued to improve markedly in recent years, driven by stunning advances in multicore processor architecture, virtualization, and the massive scalability requirements of cloud computing. A new performance reference was needed, and I eagerly waited for something that thoroughly covered modern, distributed computing performance issues from the ground up. Well, there's a new classic now, authored yet again by Brendan Gregg, former Solaris kernel engineer at Sun and now Lead Performance Engineer at Joyent. Systems Performance: Enterprise and the Cloud is a modern, very comprehensive guide to general system performance principles and practices, as well as a highly detailed reference for specific UNIX and Linux observability tools used to examine and diagnose operating system behaviour.  It provides thorough definitions of terms, explains performance diagnostic Best Practices and "Worst Practices" (called "anti-methods"), and covers key observability tools including DTrace, SystemTap, and all the traditional UNIX utilities like vmstat, ps, iostat, and many others. The book focuses on operating system performance principles and expands on these with respect to Linux (Ubuntu, Fedora, and CentOS are cited), and to Solaris and its derivatives [1]; it is not directed at any one OS so it is extremely useful as a broad performance reference. The author goes beyond the intricacies of performance analysis and shows how to interpret and visualize statistical information gathered from the observability tools.  It's often difficult to extract understanding from voluminous rows of text output, and techniques are provided to assist with summarizing, visualizing, and interpreting the performance data. Gregg includes myriad useful references from the system performance literature, including a "Who's Who" of contributors to this great body of diagnostic tools and methods. This outstanding book should be required reading for UNIX and Linux system administrators as well as anyone charged with diagnosing OS performance issues.  Moreover, the book can easily serve as a textbook for a graduate level course in operating systems [2]. [1] Solaris 11, of course, and Joyent's SmartOS (developed from OpenSolaris) [2] Gregg has taught system performance seminars for many years; I have also taught such courses...this book would be perfect for the OS component of an advanced CS curriculum.

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• How should I pitch moving to an agile/iterative development cycle with mandated 3-week deployments?

  - by Wayne M

  I'm part of a small team of four, and I'm the unofficial team lead (I'm lead in all but title, basically). We've largely been a "cowboy" environment, with no architecture or structure and everyone doing their own thing. Previously, our production deployments would be every few months without being on a set schedule, as things were added/removed to the task list of each developer. Recently, our CIO (semi-technical but not really a programmer) decided we will do deployments every three weeks; because of this I instantly thought that adopting an iterative development process (not necessarily full-blown Agile/XP, which would be a huge thing to convince everyone else to do) would go a long way towards helping manage expectations properly so there isn't this far-fetched idea that any new feature will be done in three weeks. IMO the biggest hurdle is that we don't have ANY kind of development approach in place right now (among other things like no CI or automated tests whatsoever). We don't even use Waterfall, we use "Tell Developer X to do a task, expect him to do everything and get it done". Are there any pointers that would help me start to ease us towards an iterative approach and A) Get the other developers on board with it and B) Get management to understand how iterative works? So far my idea involves trying to set up a CI server and get our build process automated (it takes about 10-20 minutes right now to simply build the application to put it on our development server), since pushing tests and/or TDD will be met with a LOT of resistance at this point, and constantly force us to break larger projects into smaller chunks that could be done iteratively in a three-week cycle; my only concern is that, unless I'm misunderstanding, an agile/iterative process may or may not release the software (depending on the project scope you might have "working" software after three weeks, but there isn't enough of it that works to let users make use of it), while I think the expectation here from management is that there will always be something "ready to go" in three weeks, and that disconnect could cause problems. On that note, is there any literature or references that explains the agile/iterative approach from a business standpoint? Everything I've seen only focuses on the developers, how to do it, but nothing seems to describe it from the perspective of actually getting the buy-in from the businesspeople.

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• Programming and Ubiquitous Language (DDD) in a non-English domain

  - by Sandor Drieënhuizen

  I know there are some questions already here that are closely related to this subject but none of them take Ubiquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with mixed languages anyway. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options? UPDATE Today, about year later, having dealt with this issue on a daily basis, I have to say that option 3 has worked out pretty well for me. It wasn't as tedious as I initially feared and translating in real time while talking to the client wasn't a problem either. I also found the following advantages to be true, based on my experience. Translating the UL makes you pay more attention to defining the UL and even the domain itself, especially when you don't know how to translate a term and you have to start looking through dictionaries etc. This has even caused me to reconsider domain modeling decisions a few times. It helps you make your knowledge of the English language more profound. Obviously, your code is much more pleasant to look at instead of being a mind boggling obscenity.

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• Good, simple reasons for having a multiple environments

  - by smp7d

  Throughout my career I had worked at companies that had a collection of different environments for different purposes. We always had more or less our desktop environment, a test environment, a QA environment, a staging environment and a production environment. This went for both servers/applications and any data sources we were using. When I started at my current company I found that 90% of the apps were either developed on a desktop environment against production data sources or developed directly on the production server depending on the platform. I wasn't phased because I was hired in part to make changes to improve the way the development team functioned, which was clear from my interview process. We slowly started to turn the philosophy and pretty soon, most of the apps could be run in either a desktop, test or production environment. Not too long after that staging came around as well. Now most of our developers see the benefit of this methodology and defend it vigilantly. However, we have a number of legacy apps that never got migrated. We also have a number of legacy programmers who think of this as a waste of time. Unfortunately, we got lip service but never full buy-in from management. We got what we thought was a commitment to invest substantially in this about a year ago, but nothing materialized despite the considerable planning that we put into it. Now we are finding that we need more and more environments. We need help from the server/network administration teams for setup and we need participation from the business stakeholders to support the release cycle. We are at a place now where a project can function what I consider "normally" only if you have the right people on the project and the time to set up the proper environments. I'd love to present a complete argument, but management really has no time and interest in hearing me out until there is a critical issue. I cant really articulate the benefits simply as it always just seemed second nature to me. I was wondering if there are any good, simple, irrefutable reasons for the separation of environments that would get managers with no development experience to get behind this idea. Are there any good resources/literature on the topic?

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• Sweden Azure Group with Michele Laroux Bustamente &amp; Maartin Balliauw Thursday 22nd May

  - by Alan Smith

  Originally posted on: http://geekswithblogs.net/asmith/archive/2014/05/19/156418.aspxSweden Azure Group (SWAG) has the privilege of welcoming Michele Laroux Bustamente and Maartin Balliauw to present sessions at our meeting this Thursday. Michele and Maartin are two of the world’s leading experts in Cloud Computing and Azure, and will be taking time out from their busy schedules to share their ideas with us, and answer any questions. Knowit Stockholm are kindly hosting the event at their offices, and providing food and refreshments. It should be a great evening. You can register for the event here. Azure Q & A - Michele Leroux Bustamante In this interactive Q & A session Michele Leroux Bustamante will be on hand to share her wealth of experience on Azure related issues. If you are new to Azure and wanting some tips to get started, or an experienced developer needing to negotiate the legal and political protocols related to Cloud Computing Michele will have been there, done that, and be willing to share her experiences. This session will be entirely driven by that attendees, so please come prepared with questions. Reducing latency on the web with the Windows Azure CDN – Maarten Balliauw Serving up content on the Internet is something our web sites do daily. But are we doing this in the fastest way possible? How are users in faraway countries experiencing our apps? Why do we have three webservers serving the same content over and over again? In this session, we’ll explore the Windows Azure Content Delivery Network or CDN, a service which makes it easy to serve up blobs, videos and other content from servers close to our users. We’ll explore simple file serving as well as some more advanced, dynamic edge caching scenarios. Michele Leroux Bustamante Michele Leroux Bustamante is CIO at Solliance (solliance.net), cofounder of Snapboard (snapboard.com), and is recognized as a Microsoft Regional Director and MVP. Michele is a thought leader with over 20 years specializing in building scalable and secure end-to-end system design, identity and access management, and cloud computing technologies – for companies of all sizes. In recent years Michele has also helped launch several startup business ventures and has been a mentor to startups in several accelerator programs – providing both technical and business guidance. Michele shares her experiences through presentations and keynotes all over the world, and has been publishing regularly in technology journals. Maarten Balliauw Maarten Balliauw is a Technical Evangelist at JetBrains. His interests are all web: ASP.NET MVC, PHP and Windows Azure. He’s a Microsoft Most Valuable Professional (MVP) for Azure and an ASPInsider. He has published many articles in both PHP and .NET literature such as MSDN magazine and PHP architect. Maarten is a frequent speaker at various national and international events such as MIX (Las Vegas), TechDays, DPC, …

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• Has test driven development (TDD) actually benefited a real world project?

  - by James

  I am not new to coding. I have been coding (seriously) for over 15 years now. I have always had some testing for my code. However, over the last few months I have been learning test driven design/development (TDD) using Ruby on Rails. So far, I'm not seeing the benefit. I see some benefit to writing tests for some things, but very few. And while I like the idea of writing the test first, I find I spend substantially more time trying to debug my tests to get them to say what I really mean than I do debugging actual code. This is probably because the test code is often substantially more complicated than the code it tests. I hope this is just inexperience with the available tools (RSpec in this case). I must say though, at this point, the level of frustration mixed with the disappointing lack of performance is beyond unacceptable. So far, the only value I'm seeing from TDD is a growing library of RSpec files that serve as templates for other projects/files. Which is not much more useful, maybe less useful, than the actual project code files. In reading the available literature, I notice that TDD seems to be a massive time sink up front, but pays off in the end. I'm just wondering, are there any real world examples? Does this massive frustration ever pay off in the real world? I really hope I did not miss this question somewhere else on here. I searched, but all the questions/answers are several years old at this point. It was a rare occasion when I found a developer who would say anything bad about TDD, which is why I have spent as much time on this as I have. However, I noticed that nobody seems to point to specific real-world examples. I did read one answer that said the guy debugging the code in 2011 would thank you for have a complete unit testing suite (I think that comment was made in 2008). So, I'm just wondering, after all these years, do we finally have any examples showing the payoff is real? Has anybody actually inherited or gone back to code that was designed/developed with TDD and has a complete set of unit tests and actually felt a payoff? Or did you find that you were spending so much time trying to figure out what the test was testing (and why it was important) that you just tossed out the whole mess and dug into the code?

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• Good, simple reasons for having multiple environments

  - by smp7d

  Throughout my career I had worked at companies that had a collection of different environments for different purposes. We always had more or less our desktop environment, a test environment, a QA environment, a staging environment and a production environment. This went for both servers/applications and any data sources we were using. When I started at my current company I found that 90% of the apps were either developed on a desktop environment against production data sources or developed directly on the production server depending on the platform. I wasn't fazed because I was hired in part to make changes to improve the way the development team functioned, which was clear from my interview process. We slowly started to turn the philosophy and pretty soon, most of the apps could be run in either a desktop, test or production environment. Not too long after that staging came around as well. Now most of our developers see the benefit of this methodology and defend it vigilantly. However, we have a number of legacy apps that never got migrated. We also have a number of legacy programmers who think of this as a waste of time. Unfortunately, we got lip service but never full buy-in from management. We got what we thought was a commitment to invest substantially in this about a year ago, but nothing materialized despite the considerable planning that we put into it. Now we are finding that we need more and more environments. We need help from the server/network administration teams for setup and we need participation from the business stakeholders to support the release cycle. We are at a place now where a project can function what I consider "normally" only if you have the right people on the project and the time to set up the proper environments. I'd love to present a complete argument, but management really has no time and interest in hearing me out until there is a critical issue. I can't really articulate the benefits simply as it always just seemed second nature to me. I was wondering if there are any good, simple, irrefutable reasons for the separation of environments that would get managers with no development experience to get behind this idea. Are there any good resources/literature on the topic?

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• Are closures with side-effects considered "functional style"?

  - by Giorgio

  Many modern programming languages support some concept of closure, i.e. of a piece of code (a block or a function) that Can be treated as a value, and therefore stored in a variable, passed around to different parts of the code, be defined in one part of a program and invoked in a totally different part of the same program. Can capture variables from the context in which it is defined, and access them when it is later invoked (possibly in a totally different context). Here is an example of a closure written in Scala: def filterList(xs: List[Int], lowerBound: Int): List[Int] = xs.filter(x => x >= lowerBound) The function literal x => x >= lowerBound contains the free variable lowerBound, which is closed (bound) by the argument of the function filterList that has the same name. The closure is passed to the library method filter, which can invoke it repeatedly as a normal function. I have been reading a lot of questions and answers on this site and, as far as I understand, the term closure is often automatically associated with functional programming and functional programming style. The definition of function programming on wikipedia reads: In computer science, functional programming is a programming paradigm that treats computation as the evaluation of mathematical functions and avoids state and mutable data. It emphasizes the application of functions, in contrast to the imperative programming style, which emphasizes changes in state. and further on [...] in functional code, the output value of a function depends only on the arguments that are input to the function [...]. Eliminating side effects can make it much easier to understand and predict the behavior of a program, which is one of the key motivations for the development of functional programming. On the other hand, many closure constructs provided by programming languages allow a closure to capture non-local variables and change them when the closure is invoked, thus producing a side effect on the environment in which they were defined. In this case, closures implement the first idea of functional programming (functions are first-class entities that can be moved around like other values) but neglect the second idea (avoiding side-effects). Is this use of closures with side effects considered functional style or are closures considered a more general construct that can be used both for a functional and a non-functional programming style? Is there any literature on this topic? IMPORTANT NOTE I am not questioning the usefulness of side-effects or of having closures with side effects. Also, I am not interested in a discussion about the advantages / disadvantages of closures with or without side effects. I am only interested to know if using such closures is still considered functional style by the proponent of functional programming or if, on the contrary, their use is discouraged when using a functional style.

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• "Whole-team" C++ features?

  - by Blaisorblade

  In C++, features like exceptions impact your whole program: you can either disable them in your whole program, or you need to deal with them throughout your code. As a famous article on C++ Report puts it: Counter-intuitively, the hard part of coding exceptions is not the explicit throws and catches. The really hard part of using exceptions is to write all the intervening code in such a way that an arbitrary exception can propagate from its throw site to its handler, arriving safely and without damaging other parts of the program along the way. Since even new throws exceptions, every function needs to provide basic exception safety — unless it only calls functions which guarantee throwing no exception — unless you disable exceptions altogether in your whole project. Hence, exceptions are a "whole-program" or "whole-team" feature, since they must be understood by everybody in a team using them. But not all C++ features are like that, as far as I know. A possible example is that if I don't get templates but I do not use them, I will still be able to write correct C++ — or will I not?. I can even call sort on an array of integers and enjoy its amazing speed advantage wrt. C's qsort (because no function pointer is called), without risking bugs — or not? It seems templates are not "whole-team". Are there other C++ features which impact code not directly using them, and are hence "whole-team"? I am especially interested in features not present in C. Update: I'm especially looking for features where there's no language-enforced sign you need to be aware of them. The first answer I got mentioned const-correctness, which is also whole-team, hence everybody needs to learn about it; however, AFAICS it will impact you only if you call a function which is marked const, and the compiler will prevent you from calling it on non-const objects, so you get something to google for. With exceptions, you don't even get that; moreover, they're always used as soon as you use new, hence exceptions are more "insidious". Since I can't phrase this as objectively, though, I will appreciate any whole-team feature. Appendix: Why this question is objective (if you wonder) C++ is a complex language, so many projects or coding guides try to select "simple" C++ features, and many people try to include or exclude some ones according to mostly subjective criteria. Questions about that get rightfully closed regularly here on SO. Above, instead, I defined (as precisely as possible) what a "whole-team" language feature is, provide an example (exceptions), together with extensive supporting evidence in the literature about C++, and ask for whole-team features in C++ beyond exceptions. Whether you should use "whole-team" features, or whether that's a relevant concept, might be subjective — but that only means the importance of this question is subjective, like always.

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• Mac Management and Security

  - by Bart Silverstrim

  I was going through some literature on managing OS X laptops and asked someone some questions about usage scenarios when using the MacBooks. I asked someone more knowledgeable than I about whether it was possible for my Mac to be taken over if I were visiting another site for a conference or if I went on a wifi network at a local coffee house with policies from an OS X Server with workgroup manager (either legit for the site or someone running a version of OS X Server on hardware they have hidden somewhere on the network), which apparently could be set up to do things like limit my access to Finder or impose other neat whiz-bang management features. He said that it is indeed possible for it to happen as it would be assigned via the DHCP server and the OS X server would assume my Mac is a guest and could hand out restrictions and apparently my Mac will happily accept them without notifying me or giving me an option, unlike Windows which I believe would need to be joined to a domain before it becomes "managed" by Active Directory. So my question is as network admins and sysadmins with users traveling with MacBooks, is there a way to reasonably protect your users from having their machines hijacked without resorting to just turning off networking all the time? Or isn't this much of a security hazard? What threat does this pose to the road warriors in your businesses?

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• Windows 32-bit and 64-bit and GPT

  - by MrLane

  I know similar questions have been asked before across several sites, but the answers at least to me have been confusing and conflicting. My understanding has always been that 64-bit Windows will create and use GPT disks just fine, but will not boot from them without a UEFI BIOS. Also my understanding WAS that 32-bit Windows could not use GPT at all and so is always restricted to 2.2TB disks, which was another reason to move to 64-bit on top of the 4GB memory limit. But I have now read that this isn't correct: 32-bit Windows will create and use GPT disks just as 64-bit does. The only resriction is that you can't boot 32-bit Windows even if you DO have a UEFI BIOS? I don't think much of the literature has explained this well. There are several tools floating around for creating virtual disks or 2.2+.8GB partition schemes and such for 32-bit systems. Why when it seems you can use GPT in 32-bit Windows anyway. It also seems that people blame MS for lagging behind with respect to all of this: but it seems the issue is with BIOS manufactures not supporting UEFI rather than MS not supporting GPT... Is my new understanding now correct?

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• Mac Management Without Permission and Security

  - by Bart Silverstrim

  I was going through some literature on managing OS X laptops and asked someone some questions about usage scenarios when using the MacBooks. I asked someone more knowledgeable than I about whether it was possible for my Mac to be taken over if I were visiting another site for a conference or if I went on a wifi network at a local coffee house with policies from an OS X Server with workgroup manager (either legit for the site or someone running a version of OS X Server on hardware they have hidden somewhere on the network), which apparently could be set up to do things like limit my access to Finder or impose other neat whiz-bang management features. He said that it is indeed possible for it to happen as it would be assigned via the DHCP server and the OS X server would assume my Mac is a guest and could hand out restrictions and apparently my Mac will happily accept them without notifying me or giving me an option, unlike Windows which I believe would need to be joined to a domain before it becomes "managed" by Active Directory. So my question is as network admins and sysadmins with users traveling with MacBooks, is there a way to reasonably protect your users from having their machines hijacked without resorting to just turning off networking all the time? Or isn't this much of a security hazard? What threat does this pose to the road warriors in your businesses?

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• A tiered approach to cloning linux partitons

  - by Djurdjura

  I'm looking at a strategy for cloning Linux (root) partitions without having to use a Live CD. Literature suggests rightly that the source and target partitions must be umounted to be able to get a clean clone. This assumes that you need to use a LiveCD. I was wondering if instead of requiring a LiveCD, if using a 3rd partition that would emulate the LiveCD functionality, if we can't achieve the same functionality. In other words, at a high level a system with 3 partitions (all bootable): Rescue Partition (LiveCD emulation) Running Partition (Source) Backup Partition (Destination) All 3 partitions are LVMS. When it's time to clone the source partition to the backup (destination) partition, we would boot to the rescue partition, unmount the other 2 partitions (is it required?), run disk check on the source, copy to the destination (dd or simple copy to avoid replicating the defragmentation from the source), run disk check on the destination partition, update Grub menu list to force boot from either partition, and reboot into that partition. My question, is it an approach that you'd recommend? MBR in all this? Any gotchas or extra checks required? Thanks, D. PS. On recommendation from members, posting here instead of stackoverflow.com.

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• Virtual Machine Network Architecture, Isolating Public and Private Networks

  - by Mark

  I'm looking for some insight into best practices for network traffic isolation within a virtual environment, specifically under VMWARE ESXi. Currently I have (in testing) 1 hardware server running ESXi but i expect to expand this to multiple pieces of hardware. The current setup is as follows: 1 pfsense VM, this VM accepts all outside (WAN/internet) traffic and performs firewall/port forwarding/NAT functionality. I have multiple public IP addresses sent to the this VM that are used for access to individual servers (via per incoming IP port forwarding rules). This VM is attached to the private (virtual) network that all other VMs are on. It also manages a VPN link into the private network with some access restrictions. This isn't the perimeter firewall but rather the firewall for this virtual pool only. I have 3 VMs that communicate with each other, as well as have some public access requirements: 1 LAMP server running an eCommerce site, public internet accessible 1 accounting server, access via windows server 2008 RDS services for remote access by users 1 inventory/warehouse management server, VPN to client terminals in warehouses These servers constantly talk with each other for data synchronization. Currently all the servers are on the same subnet/virtual network and connected to the internet through the pfsense VM. The pfsense firewall uses port forwarding and NAT to allow outside access to the servers for services and for server access to the internet. My main question is this: Is there a security benefit to adding a second virtual network adapter to each server and controlling traffic such that all server to server communication is on one separate virtual network, while any access to the outside world is routed through the other network adapter, through the firewall, and on the the internet. This is the type of architecture i would use if these were all physical servers, but i'm unsure if the networks being virtual changes the way i should approach locking down this system. Thank you for any thoughts or direction to any appropriate literature.

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• How do I prevent spawning of zombie-like apache2 processes on Dreamhost VPS?

  - by Jonathan Hayward

  I have had a website for months or longer on a DreamHost VPS, and I have had vague memories on, in initial setup, having to turn off some customized Apache under /dh to get a standard Apache 2.x to work with. Things have been going along on an even keel, when I started making some changes lately and I found that when I tried to bounce Apache (/usr/sbin/apachectl restart), it couldn't bind to port 80, and my site had been converted from a big literature site to a small parking site. I tried to see what was listening on 80, and it was a DreamHost-customized Apache that had spawned. I killed all of them, restarted Apache, and changed the parent directory under /dh to mode 000. That was a day or two ago. I was bouncing Apache again in trying to get a new site to load under HTTPS, and I found that once again DreamHost's apache had spawned, from the directory I set to mode 000, and once again converted my site to a parking page. I renamed the directory, but I am very skeptical of whether I have permanently killed the DreamHost-customized Apache. Besides duct tape options like a crontab to kill and delete each minute, how can I permanently turn off the Apache processes that are spawning from a location under /dh and interfering with standard Apache? What should I be doing that I am not? Can DreamHost's technical support stop the interference? Thanks,

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• Why do you use a 3PAR SAN? [closed]

  - by Starfish

  If you use a 3PAR SAN, I’d like to hear what you think about it, particularly compared to the HP EVA. What do you see as its advantages over other SANs like the EVA? What’s so special about the ASIC? We had HP quote us an EVA P6500 and 3PAR V400 with equivalent storage and the 3PAR was nearly twice the cost. My site has two EVA SANs with a combined capacity of ~80 TB. We want to replace the older and larger of the two. We’ve been looking at the EVA and the 3PAR to see which would be a better fit for us. I’m struggling to understand how the 3PAR differs from the EVA from a practical technical standpoint. When I read the sales literature and speak with the HP sales engineers, they spend a lot of time talking about how the 3PAR is better because of its ASIC. It’s ASIC this and ASIC that, but when I press them on how a 3PAR with thin provisioning is better than an EVA with thin provisioning, I can’t get a straight answer. Meanwhile, one of my colleagues, who has more say regarding which SAN we get, is enamored by the 3PAR, and he can’t explain clearly to me why he wants it over the EVA. Our needs are pretty simple. We have 10 servers running VMware and ~100 VMs. We use VMware’s thin provisioning currently, but we would like to start using thin provisioning on the new SAN. We don’t have a need for SSDs or migration between storage tiers. We plan on having FC or SAS drives for our most used data and SATA/FATA drives for the lesser used data which is how we have the EVAs configured. We also do not need any SAN-level snapshotting or replication.

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• scalable yet doable small-medium office network

  - by Jared

  Hello, I'm studying up with both Microsoft and Cisco literature and I must say, my head is starting to get clustered up (pun intended). I've made a quick network diagram of a theoretical company... Company1 owns Company 2 and Company 3, which are all under separate rooms and networks, but must be able to share a few resources such as files or printers. Given the amount of info out there and best practices, I thought about posting here to get suggestions and see what would the pro's do. I can read and read all day and implement on my own, but if I dont get some outside input, how will I know if I'm doing something wrong, right? anyway, please take a look and see if this is an over-complicated network or a lackluster design for a small-medium company of about 35 people and lets say they will be double that number by end of the year... :) Using win2k3, esxi, windows xp. FCS - forefront client security, ACS - access control system, SPCWK - spiceworks, XCH - Exchange Im not allowed to post an image yet, so here's the link ---- GLIFFY IMAGE Flame suit is on just in case people get mad at me for making an "abomination". I'd really want to get the general overview properly before I dive into the more complicated things

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• Apache, Tomcat and mod_jk for load balancing

  - by pHk

  Hi guys. I've set-up a basic Apache (2.2.x) and Tomcat (6.0.x) set-up using mod_jk for load balancing using the worker.properties file. Preliminary testing seems to show that this works relatively well, and it was quite easy to set-up. However; the fact that it was so easy to set-up has got me a little worried. We're dealing with 100 - 300 concurrent users using the same web application (deployed on 2 or 3 Tomcat instances). I have done a little Googling and looking around on here and there seems to be more than 1 way to accomplish this (one example on here used a balancer:// style URL, which I've never seen before in an Apache config). For example, one question I ask myself is how reliable the load detection on mod_jk really is (Busyness, Session, Request, etc). In your experience, does this set-up prove to be reliable in real world scenarios? Any pointers on improvements, pit falls or interesting literature/articles? I've worked with Apache before, but am in no way an expert. Thanks in advance.

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• What are possible results/side effects if replication between DC's in a Windows domain is unable to occur?

  - by hydroparadise

  There's plenty of administration literature out there how to properly manage Windows servers. But in dealing with real life, things don't always occur like you want them to. In Microsoft's Windows Server 2003 Administrator's Companion, out of 1400+ pages, theres only one page that I could find when it comes up setting up additional domain controlers. They make it sound seemless and don't reveal a whole lot on what happens if "peer" DC's are unable to replicate. Down to the specific issue at hand, we had a DC go down about a month ago due to a bad RAID controller. There was nothing critical that waranted imediate attention, so bringing it back up got put on the back burner. A month later, we get the DC back up and running and everyting seemed ok. The next day, nobody is able to logon complaining that the "user does not exist" or "unable to establish a trust relationship". Knowing that I had just put the downed DC back on the network, I immediately took it back off the network and had everybody restart the workstations. After that, exchange was fine, shares became available, and everybody was able to log in. After doing some event log swimming, it would appear that everything started due to replication issues on the SYSVOL. I've read where you can force replication, but that would mean putting it back on the network. I am afraid to put the DC back on the network in fear that something else could go wrong. So, what other issues could one expect to run into where two DC's are unreplicated for over a month?

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• What’s the use of code reuse?

  - by Tony Davis

  All great developers write reusable code, don’t they? Well, maybe, but as with all statements regarding what “great” developers do or don’t do, it’s probably an over-simplification. A novice programmer, in particular, will encounter in the literature a general assumption of the importance of code reusability. They spend time worrying about DRY (don’t repeat yourself), moving logic into specific “helper” modules that they can then reuse, agonizing about the minutiae of the class structure, inheritance and interface design that will promote easy reuse. Unfortunately, writing code specifically for reuse often leads to complicated object hierarchies and inheritance models that are anything but reusable. If, instead, one strives to write simple code units that are highly maintainable and perform a single function, in a concise, isolated fashion then the potential for reuse simply “drops out” as a natural by-product. Programmers, of course, care about these principles, about encapsulation and clean interfaces that don’t expose inner workings and allow easy pluggability. This is great when it helps with the maintenance and development of code but how often, in practice, do we actually reuse our code? Most DBAs and database developers are familiar with the practical reasons for the limited opportunities to reuse database code and its potential downsides. However, surely elsewhere in our code base, reuse happens often. After all, we can all name examples, such as date/time handling modules, which if we write with enough care we can plug in to many places. I spoke to a developer just yesterday who looked me in the eye and told me that in 30+ years as a developer (a successful one, I’d add), he’d never once reused his own code. As I sat blinking in disbelief, he explained that, of course, he always thought he would reuse it. He’d often agonized over its design, certain that he was creating code of great significance that he and other generations would reuse, with grateful tears misting their eyes. In fact, it never happened. He had in his head, most of the algorithms he needed and would simply write the code from scratch each time, refining the algorithms and tailoring the code to meet the specific requirements. It was, he said, simply quicker to do that than dig out the old code, check it, correct the mistakes, and adapt it. Is this a common experience, or just a strange anomaly? Viewed in a certain light, building code with a focus on reusability seems to hark to a past age where people built cars and music systems with the idea that someone else could and would replace and reuse the parts. Technology advances so rapidly that the next time you need the “same” code, it’s likely a new technique, or a whole new language, has emerged in the meantime, better equipped to tackle the task. Maybe we should be less fearful of the idea that we could write code well suited to the system requirements, but with little regard for reuse potential, and then rewrite a better version from scratch the next time.

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• What Counts For A DBA: ESP

  - by Louis Davidson

  Now I don’t want to get religious here, and I’m not going to, but what I’m going to describe in this ‘What Counts for a DBA’ installment sometimes feels like magic. Often  I will spend hours thinking about the solution to a design issue or coding problem, working diligently to try to come up with a solution and then finally just give up with the feeling that I’m not even qualified to be a data entry clerk, much less a data architect.  At this point I often take a walk (or sometimes a nap), and then it hits me. I realize that I have the answer just sitting in my brain, ready to implement.  This phenomenon is not limited to walks either; it can happen almost any time after I stop my obsession about a problem. I call this phenomena ESP (or Extra-Sensory Programming.)  Another term for this could be ‘sleeping on it’, and while the idiom tends to mean to let time pass to actively think about a problem, sleeping on a problem also lets you relax and let your brain do the work. I first noticed this back in my college days when I would play video games for hours on end. We would get stuck deep in some dungeon unable to find a way out, playing for days on end until we were beaten down tired. Once we gave up and walked away, the solution would usually be there waiting for one of us before we came back to play the next day.  Sometimes it would be in the form of a dream, and sometimes it would just be that the problem was now easy to solve when we started to play again.  While it worked great for video games, it never occurred when I studied English Literature for hours on end, or even when I worked for the same sort of frustrating hours attempting to solve a homework problem in Calculus.  I believe that the difference was that I was passionate about the video game, and certainly far less so about homework where people used the word “thou” instead of “you” or x to represent a number. This phenomenon occurs somewhat more often in my current work as a professional data programmer, because I am very passionate about SQL and love those aspects of my career choice.  Every day that I get to draw a new data model to solve a customer issue, or write a complex SELECT statement to ferret out the answer to a complex data question, is a great day. I hope it is the same for any reader of this blog.  But, unfortunately, while the day on a whole is great, a heck of a lot of noise is generated in work life. There are the typical project deadlines, along with the requisite project manager sitting on your shoulders shouting slogans to try to make you to go faster: Add in office politics, and the occasional family issues that permeate the mind, and you lose the ability to think deeply about any problem, not to mention occasionally forgetting your own name.  These office realities coupled with a difficult SQL problem staring at you from your widescreen monitor will slowly suck the life force out of your body, making it seem impossible to solve the problem This is when the walk starts; or a nap. Maybe you hide from the madness under your desk like George Costanza hides from Steinbrenner on Seinfeld.  Forget about the problem. Free your mind from the insanity of the problem and your surroundings. Then let your training and education deep in your brain take over and see if it will passively do the rest for you. If you don’t end up with a solution, the worst case scenario is that you have a bit of exercise or rest, and you won’t have heard the phrase “better is the enemy of good enough” even once…which certainly will do your brain some good. Once you stop expecting whipping your brain for information, inspiration may just strike and instead of a humdrum solution you find a solution you hadn’t even considered, almost magically. So, my beloved manager, next time you have an urgent deadline and you come across me taking a nap, creep away quietly because I’m working, doing some extra-sensory programming.

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• Type checking and recursive types (Writing the Y combinator in Haskell/Ocaml)

  - by beta

  When explaining the Y combinator in the context of Haskell, it's usually noted that the straight-forward implementation won't type-check in Haskell because of its recursive type. For example, from Rosettacode [1]: The obvious definition of the Y combinator in Haskell canot be used because it contains an infinite recursive type (a = a -> b). Defining a data type (Mu) allows this recursion to be broken. newtype Mu a = Roll { unroll :: Mu a -> a } fix :: (a -> a) -> a fix = \f -> (\x -> f (unroll x x)) $ Roll (\x -> f (unroll x x)) And indeed, the “obvious” definition does not type check: ?> let fix f g = (\x -> \a -> f (x x) a) (\x -> \a -> f (x x) a) g <interactive>:10:33: Occurs check: cannot construct the infinite type: t2 = t2 -> t0 -> t1 Expected type: t2 -> t0 -> t1 Actual type: (t2 -> t0 -> t1) -> t0 -> t1 In the first argument of `x', namely `x' In the first argument of `f', namely `(x x)' In the expression: f (x x) a <interactive>:10:57: Occurs check: cannot construct the infinite type: t2 = t2 -> t0 -> t1 In the first argument of `x', namely `x' In the first argument of `f', namely `(x x)' In the expression: f (x x) a (0.01 secs, 1033328 bytes) The same limitation exists in Ocaml: utop # let fix f g = (fun x a -> f (x x) a) (fun x a -> f (x x) a) g;; Error: This expression has type 'a -> 'b but an expression was expected of type 'a The type variable 'a occurs inside 'a -> 'b However, in Ocaml, one can allow recursive types by passing in the -rectypes switch: -rectypes Allow arbitrary recursive types during type-checking. By default, only recursive types where the recursion goes through an object type are supported. By using -rectypes, everything works: utop # let fix f g = (fun x a -> f (x x) a) (fun x a -> f (x x) a) g;; val fix : (('a -> 'b) -> 'a -> 'b) -> 'a -> 'b = <fun> utop # let fact_improver partial n = if n = 0 then 1 else n*partial (n-1);; val fact_improver : (int -> int) -> int -> int = <fun> utop # (fix fact_improver) 5;; - : int = 120 Being curious about type systems and type inference, this raises some questions I'm still not able to answer. First, how does the type checker come up with the type t2 = t2 -> t0 -> t1? Having come up with that type, I guess the problem is that the type (t2) refers to itself on the right side? Second, and perhaps most interesting, what is the reason for the Haskell/Ocaml type systems to disallow this? I guess there is a good reason since Ocaml also will not allow it by default even if it can deal with recursive types if given the -rectypes switch. If these are really big topics, I'd appreciate pointers to relevant literature. [1] http://rosettacode.org/wiki/Y_combinator#Haskell

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• SQLAuthority News – Advantages of Distance Learning

  - by Pinal Dave

  Distance education is extremely popular – almost overnight, it seems.  Almost everyone has taken an online course, or knows someone who has, or is considering joining an online school.  There are many advantages and disadvantages to attending an online school – but the same can be said of attending a physical school!  Let’s take a look at the top reasons to use distance education. 1) Flexibility.  Physical universities are usually willing to make some concessions to student – like night classes, study hours, and online networks.  However, nothing is going to beat the flexibility of distance education.  You can attend classes and take notes anytime, anywhere, wearing anything you’d like! 2) Affordability.  We don’t need to get into hard numbers to understand how an expensive university can be.  Students are taking on more and more debt just to get an education.  Many of these fees pay for room, board, and facilities.   Distance education cuts out all these costs, and makes attending school much more affordable for the average student. 3) Try before you buy.  Did you know that the average college student changes his or her major 10 times before they graduate?  You can imagine that this kind of indecision plays a huge part in WHEN you graduate – not being able to make up your mind can cost you big bucks if you have to stay in school for extra years!  Distance education allows you to take different classes from a wide range of disciplines.  Do you want to study forensic science or English literature?  Now you don’t have to pay for classes you can’t afford just to find out. 4) Pace yourself.  Some students struggle in a traditional classroom setting – classes can be taught too fast, too slow, or there are too many distractions.  Distance education allows mature students to set the pace themselves.  They can rewatch lectures they didn’t catch the first time, or go through classes quickly if they are already familiar with the material – cutting out the chance of burning out or getting bored. 5) Lifelong learning.  Maybe you already have a degree, but would like to learn more about your field, or a related field, or maybe even about something completely unrelated – just because you are curious!  Distance education allows you to learn whatever you want ,whenever you want (and yes, wearing anything you’d like!). 6) Attend whatever college you want.  Because of the popularity of distance education, physical campuses are getting in on the game by offering online courses – often just uploaded versions of classes already taught at their campus.  Ever wanted to attend Harvard, but knew you couldn’t get in?  Take a class online!  Of course, you probably should not attempt to lie and say you have a Harvard degree, but Ivy League colleges are prestigious because they are the best in their field – take advantage of the best by taking an online course! I am a big believer in continuing education, whether it is online courses, returning to school, or even take informal classes online.  Distance education can be a great way to accomplish these goals and become a lifelong learner. My friends at provides training through virtual classrooms for students who want to avoid travelling. Distance learning course allows IT aspirants to connect with trainers using the internet.  I encourage everyone to check it out! Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQL Training, T SQL, Technology

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• Is there a theory for "transactional" sequences of failing and no-fail actions?

  - by Ross Bencina

  My question is about writing transaction-like functions that execute sequences of actions, some of which may fail. It is related to the general C++ principle "destructors can't throw," no-fail property, and maybe also with multi-phase transactions or exception safety. However, I'm thinking about it in language-neutral terms. My concern is with correctly designing error handling in C++ functions that must be reliable. I would like to know what the concepts below are called so that I can learn more about them. I'm sorry that I can't ask the question more directly. Since I don't know this area I have provided an example to explain my question. The question is at the end. Here goes: Consider a sequence of steps or actions executed sequentially, where actions belong to one of two classes: those that always succeed, and those that may fail. In the examples below: S stands for an action that always succeeds (called "no-fail" in some settings). F stands for an action that may fail (for example, it might fail to allocate memory or do I/O that could fail). Consider a sequences of actions (executed sequentially from left to right): S->S->S->S Since each action in the sequence above succeeds, the whole sequence succeeds. On the other hand, the following sequence may fail because the last action may fail: S->S->S->F So, claim: a sequence has the no-fail (S) property if and only if all of its actions are no-fail. Now, I'm interested in action sequences that form "atomic transactions", with "failure atomicity," i.e. where either the whole sequence completes successfully, or there is no effect. I.e. if some action fails, the earlier ones must be rolled back. This requires that any successfully executed actions prior to a failing action must always be able to be rolled back. Consider the sequence: S->S->S->F S<-S<-S In the example above, the first row is the forward path of the transaction, and the second row are inverse actions (executed from right to left) that can be used to roll back if the final top row actions fails. It seems to me that for a transaction to support failure atomicity, the following invariant must hold: Claim: To support failure atomicity (either completion or complete roll-back on failure) all actions preceding the latest failable (F) action on the forward path (marked * in the example below) must have no-fail (S) inverses. The following is an example of a sequence that supports failure atomicity: * S->F->F->F S<-S<-S Further, if we want the transaction to be able to attempt cancellation mid-way through, but still guarantee either full completion or full rollback then we need the following property: Claim: To support failure atomicity and cancellation mid-way through execution, in the face of errors in the inverse (cancellation) path, all actions following the earliest failable (F) inverse on the reverse path (marked *) must be no-fail (S). F->F->F->S->S S<-S<-F<-F * I believe that these two conditions guarantee that an abortable/cancelable transaction will never get "stuck". My questions are: What is the study and theory of these properties called? are my claims correct? and what else is there to know? UPDATE 1: Updated terminology: what I previously called "robustness" is called atomicity in the database literature. UPDATE 2: Added explicit reference to failure atomicity, which seems to be a thing.

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