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• How can I make a universal construction more efficient?

  - by VF1

  A "universal construction" is a wrapper class for a sequential object that enables it to be linearized (a strong consistency condition for concurrent objects). For instance, here's an adapted wait-free construction, in Java, from [1], which presumes the existence of a wait-free queue that satisfies the interface WFQ (which only requires one-time consensus between threads) and assumes a Sequential interface: public interface WFQ<T> // "FIFO" iteration { int enqueue(T t); // returns the sequence number of t Iterable<T> iterateUntil(int max); // iterates until sequence max } public interface Sequential { // Apply an invocation (method + arguments) // and get a response (return value + state) Response apply(Invocation i); } public interface Factory<T> { T generate(); } // generate new default object public interface Universal extends Sequential {} public class SlowUniversal implements Universal { Factory<? extends Sequential> generator; WFQ<Invocation> wfq = new WFQ<Invocation>(); Universal(Factory<? extends Sequential> g) { generator = g; } public Response apply(Invocation i) { int max = wfq.enqueue(i); Sequential s = generator.generate(); for(Invocation invoc : wfq.iterateUntil(max)) s.apply(invoc); return s.apply(i); } } This implementation isn't very satisfying, however, since it presumes determinism of a Sequential and is really slow. I attempted to add memory recycling: public interface WFQD<T> extends WFQ<T> { T dequeue(int n); } // dequeues only when n is the tail, else assists other threads public interface CopyableSequential extends Sequential { CopyableSequential copy(); } public class RecyclingUniversal implements Universal { WFQD<CopyableSequential> wfqd = new WFQD<CopyableSequential>(); Universal(CopyableSequential init) { wfqd.enqueue(init); } public Response apply(Invocation i) { int max = wfqd.enqueue(i); CopyableSequential cs = null; int ctr = max; for(CopyableSequential csq : wfq.iterateUntil(max)) if(--max == 0) cs = csq.copy(); wfqd.dequeue(max); return cs.apply(i); } } Here are my specific questions regarding the extension: Does my implementation create a linearizable multi-threaded version of a CopyableSequential? Is it possible extend memory recycling without extending the interface (perhaps my new methods trivialize the problem)? My implementation only reduces memory when a thread returns, so can this be strengthened? [1] provided an implementation for WFQ<T>, not WFQD<T> - one does exist, though, correct? [1] Herlihy and Shavit, The Art of Multiprocessor Programming.

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• What Precalculus knowledge is required before learning Discrete Math Computer Science topics?

  - by Ein Doofus

  Below I've listed the chapters from a Precalculus book as well as the author recommended Computer Science chapters from a Discrete Mathematics book. Although these chapters are from two specific books on these subjects I believe the topics are generally the same between any Precalc or Discrete Math book. What Precalculus topics should one know before starting these Discrete Math Computer Science topics?: Discrete Mathematics CS Chapters 1.1 Propositional Logic 1.2 Propositional Equivalences 1.3 Predicates and Quantifiers 1.4 Nested Quantifiers 1.5 Rules of Inference 1.6 Introduction to Proofs 1.7 Proof Methods and Strategy 2.1 Sets 2.2 Set Operations 2.3 Functions 2.4 Sequences and Summations 3.1 Algorithms 3.2 The Growths of Functions 3.3 Complexity of Algorithms 3.4 The Integers and Division 3.5 Primes and Greatest Common Divisors 3.6 Integers and Algorithms 3.8 Matrices 4.1 Mathematical Induction 4.2 Strong Induction and Well-Ordering 4.3 Recursive Definitions and Structural Induction 4.4 Recursive Algorithms 4.5 Program Correctness 5.1 The Basics of Counting 5.2 The Pigeonhole Principle 5.3 Permutations and Combinations 5.6 Generating Permutations and Combinations 6.1 An Introduction to Discrete Probability 6.4 Expected Value and Variance 7.1 Recurrence Relations 7.3 Divide-and-Conquer Algorithms and Recurrence Relations 7.5 Inclusion-Exclusion 8.1 Relations and Their Properties 8.2 n-ary Relations and Their Applications 8.3 Representing Relations 8.5 Equivalence Relations 9.1 Graphs and Graph Models 9.2 Graph Terminology and Special Types of Graphs 9.3 Representing Graphs and Graph Isomorphism 9.4 Connectivity 9.5 Euler and Hamilton Ptahs 10.1 Introduction to Trees 10.2 Application of Trees 10.3 Tree Traversal 11.1 Boolean Functions 11.2 Representing Boolean Functions 11.3 Logic Gates 11.4 Minimization of Circuits 12.1 Language and Grammars 12.2 Finite-State Machines with Output 12.3 Finite-State Machines with No Output 12.4 Language Recognition 12.5 Turing Machines Precalculus Chapters R.1 The Real-Number System R.2 Integer Exponents, Scientific Notation, and Order of Operations R.3 Addition, Subtraction, and Multiplication of Polynomials R.4 Factoring R.5 Rational Expressions R.6 Radical Notation and Rational Exponents R.7 The Basics of Equation Solving 1.1 Functions, Graphs, Graphers 1.2 Linear Functions, Slope, and Applications 1.3 Modeling: Data Analysis, Curve Fitting, and Linear Regression 1.4 More on Functions 1.5 Symmetry and Transformations 1.6 Variation and Applications 1.7 Distance, Midpoints, and Circles 2.1 Zeros of Linear Functions and Models 2.2 The Complex Numbers 2.3 Zeros of Quadratic Functions and Models 2.4 Analyzing Graphs of Quadratic Functions 2.5 Modeling: Data Analysis, Curve Fitting, and Quadratic Regression 2.6 Zeros and More Equation Solving 2.7 Solving Inequalities 3.1 Polynomial Functions and Modeling 3.2 Polynomial Division; The Remainder and Factor Theorems 3.3 Theorems about Zeros of Polynomial Functions 3.4 Rational Functions 3.5 Polynomial and Rational Inequalities 4.1 Composite and Inverse Functions 4.2 Exponential Functions and Graphs 4.3 Logarithmic Functions and Graphs 4.4 Properties of Logarithmic Functions 4.5 Solving Exponential and Logarithmic Equations 4.6 Applications and Models: Growth and Decay 5.1 Systems of Equations in Two Variables 5.2 System of Equations in Three Variables 5.3 Matrices and Systems of Equations 5.4 Matrix Operations 5.5 Inverses of Matrices 5.6 System of Inequalities and Linear Programming 5.7 Partial Fractions 6.1 The Parabola 6.2 The Circle and Ellipse 6.3 The Hyperbola 6.4 Nonlinear Systems of Equations

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

  - by Aaronaught

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

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• What is the use of Association, Aggregation and Composition (Encapsulation) in Classes

  - by SahilMahajanMj

  I have gone through lots of theories about what is encapsulation and the three techniques of implementing it, which are Association, Aggregation and Composition. What i found is, Encapsulation Encapsulation is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. For this reason, encapsulation is also referred to as data hiding. Encapsulation can be described as a protective barrier that prevents the code and data being randomly accessed by other code defined outside the class. Access to the data and code is tightly controlled by an interface. The main benefit of encapsulation is the ability to modify our implemented code without breaking the code of others who use our code. With this feature Encapsulation gives maintainability, flexibility and extensibility to our code. Association Association is a relationship where all object have their own lifecycle and there is no owner. Let’s take an example of Teacher and Student. Multiple students can associate with single teacher and single student can associate with multiple teachers but there is no ownership between the objects and both have their own lifecycle. Both can create and delete independently. Aggregation Aggregation is a specialize form of Association where all object have their own lifecycle but there is ownership and child object can not belongs to another parent object. Let’s take an example of Department and teacher. A single teacher can not belongs to multiple departments, but if we delete the department teacher object will not destroy. We can think about “has-a” relationship. Composition Composition is again specialize form of Aggregation and we can call this as a “death” relationship. It is a strong type of Aggregation. Child object dose not have their lifecycle and if parent object deletes all child object will also be deleted. Let’s take again an example of relationship between House and rooms. House can contain multiple rooms there is no independent life of room and any room can not belongs to two different house if we delete the house room will automatically delete. The question is: Now these all are real world examples. I am looking for some description about how to use these techniques in actual class code. I mean what is the point for using three different techniques for encapsulation, How these techniques could be implemented and How to choose which technique is applicable at time.

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• Avoiding the Black Hole of Leads

  - by Charles Knapp

  Sales says, "Marketing doesn’t deliver enough qualified leads. So, we generate 90% of our own leads." Meanwhile, Marketing says, "We generate most of the leads. But, Sales doesn’t contact them quickly enough, while the lead is still interested." According to Sirius Decisions: Up to 90% of leads never make it to closure Sales works on only 11% of the leads supplied by Marketing Only 18% of the leads Sales accepts convert to opportunities Yet, 45% of prospects typically buy a product from someone within 12 months The root cause of these commonplace complaints is a disconnect between the funnels of marketing and sales. Unfortunately, we often see companies with an assortment of poorly integrated marketing tools. It takes too long and too many people to move the data around, scrub it, upload it from one system to another, and get it routed to the right sales teams. As a result, leads fall through the cracks, contextual information is lost, and by the time sales actually contacts a customer it may be too late. Sales automation alone is not enough. Marketing automation (including social) is not enough. Sales and Marketing must work together. It’s time to connect the silos of marketing and sales pipelines and analytics. It’s time for integrated Sales and Marketing automation. Integrated pipelines improve lead quality and timeliness. Marketing systems can track a rich set of contextual information about a prospect–self-disclosed information about interests, content viewed, and so on. This insight can equip the sales rep with rich information to make a face-to-face conversation more relevant and more likely to convert to the next stage in the sales process. Integrated lead to revenue (LTR) management provides end-to-end visibility, enabling the company to measure what is working. Marketing can measure its impact on revenue and other business outcomes, and sales can harness and redirect marketing investments to areas where they most help achieve sales objectives. It’s a win-win play. Marketing delivers more leads that are qualified, cuts cost per lead, and demonstrates a strong Return on Marketing Investment (ROMI). Sales spends more time with warm leads and less time on cold calls, achieves higher close rates, and delivers more revenue. Learn more by attending our Integrated Sales and Marketing session at the upcoming CloudWorld conferences. Or, visit our Sales and Marketing Cloud Service site for videos and other learning resources.

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• Develop web site from existing software or cherry pick and use a web framework?

  - by erisco

  A small team and I are tasked with developing a web site. The client has referenced a particular open source project (we'll call it X) when describing some of the features. Because of this, the team wants to start with X and adapt it to satisfy the client. I have looked at X and its code and, in my opinion, it would be unwise. However, my experience is limited, and could really benefit from the insights of others so that I can figure out what I should be asserting as the right direction for the team. My red flags are going up and this is why. X was developed in the earlier days of PHP; 500 line blocks of code are the norm; global variables are abundant; giant switch cases are the norm for switching between which page is shown. There is no clear mapping between URL and where the code for that page sits. From a feature-set standpoint, X is actually software specialized for a different task and has dozens of features we don't need or have use for that come as core assumptions. We will be unable to adapt X through its plugin system. That said, there are a few features which can be mapped, with some modification, to suit our purposes. I believe this is the attraction the team feels. I would feel comfortable if, instead of using X directly, we lifted what is salvageable and useful to us. We can then use that code, and the same 3rd party libraries X is using, in a new code base built on top of a PHP web framework (particularly Agavi, so you understand what I mean by 'web framework'). The web framework gives us a strong MVC structure and provides the common facilities for web development, or adapters to work with 3rd party libraries that do so. We will also have a clean slate feature-wise to work from, which means we can work additively instead of subtractively. Because the code base is better structured, and contains none of what we don't need, it will be easier to document, which is a critical requirement of our client. So to summarize, the team wants to use X, whereas I want to take the bits we can from X and use a web framework instead. I want to bounce this opinion off of other's experiences so that I can be more informed. Thanks for your insight.

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• Cloud Infrastructure has a new standard

  - by macoracle

  I have been working for more than two years now in the DMTF working group tasked with creating a Cloud Management standard. That work has culminated in the release today of the Cloud Infrastructure Management Interface (CIMI) version 1.0 by the DMTF. CIMI is a single interface that a cloud consumer can use to manage their cloud infrastructure in multiple clouds. As CIMI is adopted by the cloud vendors, no more will you need to adapt client code to each of the proprietary interfaces from these multiple vendors. Unlike a de facto standard where typically one vendor has change control over the interface, and everyone else has to reverse engineer the inner workings of it, CIMI is a de jure standard that is under change control of a standards body. One reason the standard took two years to create is that we factored in use cases, requirements and contributed APIs from multiple vendors. These vendors have products shipping today and as a result CIMI has a strong foundation in real world experience. What does CIMI allow? CIMI is both a model for the resources (computing, storage networking) in the cloud as well as a RESTful protocol binding to HTTP. This means that to create a Machine (guest VM) for example, the client creates a “document” that represents the Machine resource and sends it to the server using HTTP. CIMI allows the resources to be encoded in either JavaScript Object Notation (JSON) or the eXentsible Markup Language (XML). CIMI provides a model for the resources that can be mapped to any existing cloud infrastructure offering on the market. There are some features in CIMI that may not be supported by every cloud, but CIMI also supports the discovery of which features are implemented. This means that you can still have a client that works across multiple clouds and is able to take full advantage of the features in each of them. Isn’t it too early for a standard? A key feature of a successful standard is that it allows for compatible extensions to occur within the core framework of the interface itself. CIMI’s feature discovery (through metadata) is used to convey to the client that additional features that may be vendor specific have been implemented. As multiple vendors implement such features, they become candidates to add the future versions of CIMI. Thus innovation can continue in the cloud space without being slowed down by a lowest common denominator type of specification. Since CIMI was developed in the open by dozens of stakeholders who are already implementing infrastructure clouds, I expect to CIMI being adopted by these same companies and others over the next year or two. Cloud Customers who can see the benefit of this standard should start to ask their cloud vendors to show a CIMI implementation in their roadmap.  For more information on CIMI and the DMTF's other cloud efforts, go to: http://dmtf.org/cloud

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• Exalytics OBI11g Partner Training 3-day hands-on Workshops

  - by Mike.Hallett(at)Oracle-BI&EPM

  These FREE to OPN Partners hands-on workshops highlight both the hardware and software components that are engineered to work together to deliver Oracle Exalytics - an optimized version of the industry-leading Oracle TimesTen In-Memory Database with analytic extensions, a highly scalable Oracle server designed specifically for in-memory business intelligence, and Oracle's proven Business Intelligence Foundation (OBI 11g v 11.1.1.6 and Essbase) with enhanced visualization capabilities and performance optimizations. Priority will be given to Partner individuals who have passed or scheduled to take the Oracle Business Intelligence Foundation Suite 11g Essentials (1Z1-591) exam, and to Partners who have purchased an Exalytics for their own data centres to demonstrate it to their clients. Topics covered will include: Exalytics Architectural Overview Upgrade and Lifecycle Management Times Ten for Exalytics Summary Advisor Utility Essbase and EPM System on Exalytics Dashboard and Analysis Interactions OBIEE 11.1.1.6 Features and Advanced Topics After taking this course, you will be well prepared to architect, build, demo, and implement an end-to-end Exalytics solution.You will also be able to extend your current analytical and enterprise performance management application implementations with numerous Oracle technologies specifically enhanced to take advantage of the compute capacity and in-memory capabilities of Oracle Exalytics. Prerequisites Experience and understanding of OBIEE 11g is required ·       Previous attendance of Oracle Business Intelligence Foundation Suite Workshop or BIEE 11g Introduction Workshop is highly recommended, and priority will be given to Partner individuals who have passed or scheduled to take the Oracle Business Intelligence Foundation Suite 11g Essentials (1Z1-591) exam. Good understanding of data warehousing and data modelling for reporting and analysis purpose.  Strong experience with database technologies preferred Attendee to provide their own laptops which must meet the following minimum hardware/software requirements: Hardware Minimum 8GB RAM 60 GB free disk space (includes staging) USB 2.0 port (at least one available) It is strongly recommended that you bring a mouse. You will be working in a development environment and using the mouse heavily. Software One of the following operating systems: 64-bit Windows host/laptop OS 64-bit host/laptop OS with a Windows VM (XP, Server, or Win 7, BIC2g, etc.) Internet Explorer 7.x/8.x or Firefox 3.5.x WINRAR or 7ziputility to unzip workshop files: Download-able from http://www.win-rar.com/download.html Download-able from http://www.7zip.com/ Oracle VirtualBox 4.0.2 or higher Downloadable from http://www.virtualbox.org/wiki/Downloads CPU virtualization mode needs to be enabled. We will provide guidance on the day of the workshop.  Attendees will be given a VirtualBox image containing a pre-installed Oracle Exalytics environment. Register Here for 3-day Workshops: 11-Dec-12 Birmingham UK 29-Jan-13 Utrecht NL 12-Feb-13 Frankfurt Germany 12-Mar-13 Moscow Russia

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• Moms on Mobile: Are They Way Ahead of You?

  - by Mike Stiles

  You may have no idea how much and how fast moms are embracing mobile. Of all the demographics that can be targeted by marketers, moms have always been at or near the top of the list. And why not? They’re running households, they’re all over town, they’re making buying decisions, and they’re influencing family and friends. They, out of necessity, become masters of efficiency and time management. So when a technology tool, like mobile, comes along that assists with that efficiency and time management, we would obviously expect them to take advantage of it. So if it’s obvious, why are so many big, sophisticated brands left choking on the dust of moms who have zoomed past them in the adoption of mobile, and social on mobile? Let’s break down some hard truths as presented by a Mojiava report: -Moms spend 6.1 hours per day on average on their smartphones – more than magazines, TV or radio. -46% took action after seeing a mobile ad. -51% self-identify as “addicted” to their smartphone. -Households with an income of $25K-$50K have about the same mobile penetration among moms as those with incomes of $50K-$75K. So mobile is regarded as a necessity for middle-class moms. -Even moms without smartphones spend 2.5 hours on average per day on some connected mobile device. -Of moms with such devices, 9.8% have an iPad, 9.5% a Kindle and 5.7% an iPod Touch. -Of tablet-owning moms, 97% bought something using their tablet in the last month. -31% spend over 10 hours per week on their tablet, but less than 2 hours per week on their PCs. -62% of connected moms use shopping apps. -46% want to get info on their mobile while in a store. -Half of connected moms use social on their mobile. And they’re engaged. 81% are brand fans, 86% post updates, and 84% comment. If women and moms are one of your primary targets and you find yourself with no strong social channels where content is driving engagement and relationship-building, with sites not optimized for mobile, or with no tablet or smartphone apps, you have been solidly left behind by your customers and prospects. And their adoption of mobile and social on mobile is only exponentially speeding up, not slowing down. How much sense does it make when your customer is ready to act on your mobile ad, wants to user your iPad app to buy something from you, wants to be your fan on Facebook, wants to get messages and deals from you while they’re in your store…but you’re completely absent? I’ll help you cheat on the test by giving you the answer…no sense at all. Catch up to momma.

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• Where does a "Technical Programmer" fit in, and what does the title mean? [closed]

  - by Mike E

  Was: "What is a 'Technical Programmer'"? I've noticed in job posting boards a few postings, all from European companies in the games industry, for a "Technical Programmer". The job description was similar, having to do with tools development, 3d graphics programming, etc. It seems to be somewhere between a Technical Artist who's more technical than artist or who can code, and a Technical Director but perhaps without the seniority/experience. Information elsewhere on the position is sparse. The title seems redundant and I haven't seen any American companies post jobs by that name, exactly. One example is this job posting on gamedev.net which isn't exactly thorough. In case the link dies: Subject: Technical Programmer Frictional Games, the creators of Amnesia: The Dark Descent and the Penumbra series, are looking for a talented programmer to join the company! You will be working for a small team with a big focus on finding new and innovating solutions. We want you who are not afraid to explore uncharted territory and constantly learn new things. Self-discipline and independence are also important traits as all work will be done from home. Some the things you will work with include: 3D math, rendering, shaders and everything else related. Console development (most likely Xbox 360). Hardware implementations (support for motion controls, etc). All coding is in C++, so great skills in that is imperative. Revised Summarised Question: So, where does a programmer of this nature fit in to software development team? If I had these on my team, what tasks am I expecting them to complete? Can I ask one to build a new level editor, or optimize the rendering engine? It doesn't seem to be a "tools programmer" which focuses on producing artist tools, often in high-level languages like C#, Python, or Java. Nor does it seem to be working directly on the engine, nor a graphics programmer, as such. Yet, a strong C++ requirement, which was mirrored in other postings besides this one I quoted. Edited To Add As far as it being a low-level programmer, I had considered that but lacking from the posting was a requirement of Assembly. Instead, they tend to require familiarity with higher-level hardware APIs such as DirectX, or DirectInput. I wasn't fully clear in my original post. I think, however, that Mathew Foscarini has it right in his answer, so barring someone who definitely works with or as a "Technical Programmer" stepping in to provide a clearer explanation, I'll go with that. A generalist, which also fits the description of a more-technical-than-artist TA.

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• How do I server multiple domains from the same directory and codebase without my configuraton breaking when apache.conf is overwritten?

  - by neokio

  I have 20 domains on a VPS running cPanel. One public_html is filled with code, the remaining 19 are symbolic links to that one. (For example, assets is a directory within public_html ... for the 19 others, there's a symbolic link to that directory in each each accounts public_html dir.) It's all PHP / MySQL database driven, with content changing depending on the domain. It works like a charm, assuming cPanel has suExec enabled correctly, and assuming apache.conf does NOT have SymLinksIfOwnerMatch enabled. However, every few weeks, my apache.conf is mysteriously overwritten, re-enabling SymLinksIfOwnerMatch, and disabling all 19 linked sites for as long as it takes for me to notice. Here's the offending line in apache.conf: <Directory "/"> AllowOverride All Options ExecCGI FollowSymLinks IncludesNOEXEC Indexes SymLinksIfOwnerMatch </Directory> The addition of SymLinksIfOwnerMatch disables the sites in a strange way ... the html is generated correctly, but all css/js/image in the html fails to load. Clicking any link redirects to /. And I have no idea why. I do have a few things in my .htaccess, which work fine when SymLinksIfOwnerMatch is not present: <IfModule mod_rewrite.c> # www.example.com -> example.com RewriteCond %{HTTPS} !=on RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC] RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L] # Remove query strings from static resources RewriteRule ^assets/js/(.*)_v(.*)\.js /assets/js/$1.js [L] RewriteRule ^assets/css/(.*)_v(.*)\.css /assets/css/$1.css [L] RewriteRule ^assets/sites/(.*)/(.*)_v(.*)\.css /assets/sites/$1/$2.css [L] # Block access to hidden files and directories RewriteCond %{SCRIPT_FILENAME} -d [OR] RewriteCond %{SCRIPT_FILENAME} -f RewriteRule "(^|/)\." - [F] # SLIR ... reroute images to image processor RewriteCond %{REQUEST_URI} ^/images/.*$ RewriteRule ^.*$ - [L] # ignore rules if URL is a file RewriteCond %{REQUEST_FILENAME} !-f # ignore rules if URL is not php #RewriteCond %{REQUEST_URI} !\.php$ # catch-all for routing RewriteRule . index.php [L] </ifModule> I also use most of the 5G Blacklist 2013 for protection against exploits and other depravities. Again, all of this works great, except when SymLinksIfOwnerMatch gets added back into apache.conf. Since I've failed to find the cause of whatever cPanel/security update is overwriting apache.conf, I thought there might be a more correct way to accomplish my goal using group permissions. I've created a 'www' group, added all accounts to the group, and chmod -R'd the code source to use that group. Everything is 644 or 755. But doesn't seem to be enough. My unix isn't that strong. Do you need to restart something for group changes to take effect? Probably not. Anyways, I'm entering unknown territory. Can anyone recommend the right way to configure a website for multiple sites using one codebase that doesn't rely on apache.conf?

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• Reasons NOT to use JSF [closed]

  - by Vain Fellowman

  I am new to StackExchange, but I figured you would be able to help me. We're crating a new Java Enterprise application, replacing an legacy JSP solution. Due to many many changes, the UI and parts of the business logic will completely be rethought and reimplemented. Our first thought was JSF, as it is the standard in Java EE. At first I had a good impression. But now I am trying to implement a functional prototype, and have some really serious concerns about using it. First of all, it creates the worst, most cluttered invalid pseudo-HTML/CSS/JS mix I've ever seen. It violates every single rule I learned in web-development. Furthermore it throws together, what never should be so tightly coupled: Layout, Design, Logic and Communication with the server. I don't see how I would be able to extend this output comfortably, whether styling with CSS, adding UI candy (like configurable hot-keys, drag-and-drop widgets) or whatever. Secondly, it is way too complicated. Its complexity is outstanding. If you ask me, it's a poor abstraction of basic web technologies, crippled and useless in the end. What benefits do I have? None, if you think about. Hundreds of components? I see ten-thousands of HTML/CSS snippets, ten-thousands of JavaScript snippets and thousands of jQuery plug-ins in addition. It solves really many problems - we wouldn't have if we wouldn't use JSF. Or the front-controller pattern at all. And Lastly, I think we will have to start over in, say 2 years. I don't see how I can implement all of our first GUI mock-up (Besides; we have no JSF Expert in our team). Maybe we could hack it together somehow. And then there will be more. I'm sure we could hack our hack. But at some point, we'll be stuck. Due to everything above the service tier is in control of JSF. And we will have to start over. My suggestion would be to implement a REST api, using JAX-RS. Then create a HTML5/Javascript client with client side MVC. (or some flavor of MVC..) By the way; we will need the REST api anyway, as we are developing a partial Android front-end, too. I doubt, that JSF is the best solution nowadays. As the Internet is evolving, I really don't see why we should use this 'rake'. Now, what are pros/cons? How can I emphasize my point to not use JSF? What are strong points to use JSF over my suggestion?

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• Zscaler. Certs, cookies, and port 80 traffic

  - by 54's_lol

  So I work at HQ for a large company that shall remain nameless. We use Zscaler and I had to roll out a 2048 cert per zscaler's request. People around me at work dont understand the technology and think that the cert's are what is allowing internet connectivity. From my understanding(and please chime in) is the cookie located C:\Users\$$$$$$4$$\AppData\Roaming\Macromedia\Flash Player#SharedObjects\Q3JQJQJV\gateway.zscaler.net\zscaler.swf here that gets created when you provide your creds the first time you use the browser. The cert's are just simply a way of inspecting the SSL traffic as zscaler had no way of doing this before without them. They are essentially using the classic MITM attack to parse your SSL traffic. Gmail is smart enough to recognize this as you get a warning. My question is this, is there a product or service that I can use to verify my web browser when at home(I.E. off company network) isn't still getting routed to zscaler's cloud? If i do a tracert that will work fine. It's the port 80 and 443 web traffic zscaler and my company is after. I would like to verify that when I'm off their premise that my web traffic is using only my isp and the path to whatever content I'm searching for. Do the cert's i'm pushing and browser authentication do something behind the curtain that forces web traffic to get routed to zscaler? I searched quite a bit and would very much like to know if I'm ever off company scrutiny. I do know zscaler offers the service to force the scenario im asking about. Can I prove how my web traffic is getting routed? Thanks for any insight. I've been a fan for a long time and your guy's kung fu is very strong:-)

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• USB Hardware vs. Software Write Lock

  - by TreyK

  I'm in the market for a USB flash drive, and remember this cool feature a tiny 32MB flash drive of mine had: a write lock switch. This seemed like it would be an amazing feature to have as a shield against any nastiness happening to the drive on an unfamiliar computer. However, very few drives on the market offer this feature. Instead, it seems that forms of software protection are the more prominent method. This software protection causes me a bit of uneasiness, as it seems like this software wouldn't be nearly as bulletproof as a physical switch. Also, levels of protection seem to vary from product to product. Being able to protect certain folders from reading and/or writing would be nice, but is the security trade-off worth it? Just how effective can this software protection be? Wouldn't a simple format be able to clean any drive with software protection? My drive must also be compatible with Windows XP, Vista, and 7, as well as Linux and Mac. What would be the best way forward for getting a well-sized (~8GB) flash drive with a strong write protection implementation, for little or no more than a regular drive? Thanks.

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• Computer specs for a large database

  - by SpeksETC

  What sort of computer specs (CPU, RAM, disk speed) should I use for running queries on a database of 200+ million records? The queries are for a research project, so there is only one "user" and only one query will be running at a time. I tried it on my own laptop with SQL Server with an i3 processor, 2GB RAM, 5400 RPM disk and a simple query didn't finish even after 8+ hours. I have an option to connect a SSD via eSata and upgrade to 4GB RAM, but not sure if this will be enough... Thanks! Edit: The database is about 25 GB and the indexes are not setup properly. When I tried to add an index, I let it run for about 8 hours and it still hadn't finished so I gave up. Should I have more patience :)? In general, the queries will run once in a while and its ok even if it takes a couple hours to complete.... Also, the queries will produce probably about 10 million records which I need to process using Stata/Matlab and I'm concerned that my current laptop is not strong enough, but unsure of the bottleneck....

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• Variable size encrypted container

  - by Cray

  Is there an application similar to TrueCrypt, but the one that can make variable size containers opposed to fixed-size or only-growing-to-certain-amount containers which can be made by TrueCrypt? I want this container to be able to be mounted to a drive/folder, and the size of the outer container not be much different from the total size of all the files that I put into the mounted folder, while still providing strong encryption. If to put it in other words, I want a program like truecrypt, which not only automatically grows the container if I put in new files, but also decreases it's size if some files are deleted. I know there are some issues of course, and it would not work 100% as truecrypt, because it basically works on the sector level of the disk, giving all the filesystem-control to the OS, and so when I remove a file, it might as well be left there, or there might be some fragmentation issues that would stop just truncating the volume from working, but perhaps a program can be built in some other way? Instead of providing sector-level interface, it would provide filesystem-level interface? A filesystem inside a file which would support shrinking when files are deleted?

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• Sophos UTM in Hyper-V

  - by TheD

  So, I had a previous thread about this Virtualizing Firewalls/UTM. Essentially, I have configured what I think would work, but networking isn't my strong point! Two Virtual Adapters - with IP addresses 192.168.0.2 (External) and 192.168.0.3 (Internal) respectively. The External Adapater looks at 192.168.0.1 (my Zyxel) for it's default gateway. The Internal Adapter, 192.168.0.3, which is what the Sophos UTM listens on, has it's default gateway set to 192.168.0.2, the IP of the External Lan interface. So, PC (192.168.0.11, DHCP) --> (LAN) --> Switch --> 192.168.0.3 (Internal LAN Interface IP) --> Sophos UTM --> 192.168.0.2 (External LAN Interface IP) --> 192.168.0.1 --> Internet Would this be the correct setup, or am I completely out of the game here? Cheers!

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• The physical working paradigm of a signal passing on wire.

  - by smwikipedia

  Hi, This may be more a question of physics, so pardon me if there's any inconvenience. When I study computer networks, I often read something like this in order to represent a signal, we place some voltage on one end of the wire and the other end will detect the voltage and thus the signal. So I am wondering how a signal exactly passes through wire? Here's my current understanding based on my formal knowledge about electronics: First we need a close circuit to constrain/hold the electronic field. When we place a voltage at somewhere A of the circuit, electronic field will start to build up within the circuit medium, this process should be as fast as light speed. And as the electronic field is being built up, the electrons within the circuit medium are moved, and thus electronic current occurs, and once the electronic current is strong enough to be detected at somewhere else B on the complete circuit, then B knows about what has happend at A and thus communication between A and B is achieved. The above is only talking about the process of sending a single voltage through wire. If there's a bitstream and we need to send a series of voltages, I am not sure which of the following is true: The 2nd voltage should only be sent from A after the 1st voltage has been detected at B, the time interval is time needed to stimulate the electronic field in the medium and form a detectable electronic current at B. Several different voltages could be sent on wire one by one, different electronic current values will exists along the wire simutaneously and arrive at B successively. I hope I made myself clear and someone else has ever pondered this question. (I tag this question with network cause I don't know if there's a better option.) Thanks, Sam

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• What to do before connecting Ubuntu Server to the internet for the first time?

  - by CodeMonkey

  I just finished installing Ubuntu Server 12.10 on an Asus Eee PC 1000H (to be used as a home server/sandbox) from USB. I installed this software during installation: OpenSSH server LAMP server Samba file server Virtual Machine host I won't use 2, 3 or 4 for a while though. Can/should I turn these off somehow? I have turned home directory encryption on. Security updates are installed automatically. I have chosen a strong password for the single user. I have never plugged in the internet cable so far. Before doing so I'd like to ask: What can/should I do/install to increase security before connecting to the internet? Firewall? Fail2ban? Users/Passwords? Encryption? Enable/Disable functionality? etc. I'm sorry if you get this question a lot. I've searched around quite a while, but it still feels like I might overlook something important.

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• Samba server NETBIOS name not resolving, WINS support not working

  - by Eric

  When I try to connect to my CentOS 6.2 x86_64 server's samba shares using address \\REPO (NETBIOS name of REPO), it times out and shows an error; if I do so directly via IP, it works fine. Furthermore, my server does not work correctly as a WINS server despite my samba settings being correct for it (see below for details). If I stop the iptables service, things work properly. I'm using this page as a reference for which ports to use: http://www.samba.org/samba/docs/server_security.html Specifically: UDP/137 - used by nmbd UDP/138 - used by nmbd TCP/139 - used by smbd TCP/445 - used by smbd I really really really want to keep the secure iptables design I have below but just fix this particular problem. SMB.CONF [global] netbios name = REPO workgroup = AWESOME security = user encrypt passwords = yes # Use the native linux password database #passdb backend = tdbsam # Be a WINS server wins support = yes # Make this server a master browser local master = yes preferred master = yes os level = 65 # Disable print support load printers = no printing = bsd printcap name = /dev/null disable spoolss = yes # Restrict who can access the shares hosts allow = 127.0.0. 10.1.1. [public] path = /mnt/repo/public create mode = 0640 directory mode = 0750 writable = yes valid users = mangs repoman IPTABLES CONFIGURE SCRIPT # Remove all existing rules iptables -F # Set default chain policies iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT DROP # Allow incoming SSH iptables -A INPUT -i eth0 -p tcp --dport 22222 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 22222 -m state --state ESTABLISHED -j ACCEPT # Allow incoming HTTP #iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT #iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT # Allow incoming Samba iptables -A INPUT -i eth0 -p udp --dport 137 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p udp --sport 137 -m state --state ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p udp --dport 138 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p udp --sport 138 -m state --state ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 139 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 139 -m state --state ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 445 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 445 -m state --state ESTABLISHED -j ACCEPT # Make these rules permanent service iptables save service iptables restart**strong text**

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• With WebMatrix, How do I Connect to a MySQL Database on a Colleague's Machine?

  - by Ash Clarke

  I have scoured Google trying to discover how to do this, but essentially I want to connect to a colleague's MySQL database for working together on a Wordpress installation. I am having no luck and keep getting an error about the connection not being possible: Unable to connect to any of the specified MySQL hosts. MySql.Data.MySqlClient.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts. at MySql.Data.MySqlClient.NativeDriver.Open() at MySql.Data.MySqlClient.Driver.Open() at MySql.Data.MySqlClient.Driver.Create(MySqlConnectionStringBuilder settings) at MySql.Data.MySqlClient.MySqlPool.GetPooledConnection() at MySql.Data.MySqlClient.MySqlPool.TryToGetDriver() at MySql.Data.MySqlClient.MySqlPool.GetConnection() at MySql.Data.MySqlClient.MySqlConnection.Open() at Microsoft.WebMatrix.DatabaseManager.MySqlDatabase.MySqlDatabaseProvider.TestConnection(String connectionString) at Microsoft.WebMatrix.DatabaseManager.IisDbManagerModuleService.TestConnection(DatabaseConnection databaseConnection, String configPathState) at Microsoft.WebMatrix.DatabaseManager.Client.ClientConnection.Test(ManagementConfigurationPath configPath) at Microsoft.WebMatrix.DatabaseManager.Client.DatabaseHierarchyInfo.EnsureLoaded() The connection details are copied from my colleague's connection string, with the exception of the server being modified to match the IP address of his machine. I'm not sure if there is a firewall port I have to open or a configuration file I have to modify, but I'm not having much luck so far. (There is a strong chance that, by default, web matrix / iis express doesn't set the mysql database it creates to accept remote connections. If anyone knows how to change this, that would be grand!) Anyone have any ideas?

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• Identifying and Resolving Oracle ITL Deadlock

  - by Allan

  I have an Oracle DB package that is routinely causing what I believe is an ITL (Interested Transaction List) deadlock. The relevant portion of a trace file is below. Deadlock graph: ---------Blocker(s)-------- ---------Waiter(s)--------- Resource Name process session holds waits process session holds waits TM-0000cb52-00000000 22 131 S 23 143 SS TM-0000ceec-00000000 23 143 SX 32 138 SX SSX TM-0000cb52-00000000 30 138 SX 22 131 S session 131: DID 0001-0016-00000D1C session 143: DID 0001-0017-000055D5 session 143: DID 0001-0017-000055D5 session 138: DID 0001-001E-000067A0 session 138: DID 0001-001E-000067A0 session 131: DID 0001-0016-00000D1C Rows waited on: Session 143: no row Session 138: no row Session 131: no row There are no bit-map indexes on this table, so that's not the cause. As far as I can tell, the lack of "Rows waited on" plus the "S" in the Waiter waits column likely indicates that this is an ITL deadlock. Also, the table is written to quite often (roughly 8 insert or updates concurrently, as often as 240 times a minute), so and ITL deadlock seems like a strong possibility. I've increased the INITRANS parameter of the table and it's indexes to 100 and increased the PCT_FREE on the table from 10 to 20 (then rebuilt the indexes), but the deadlocks are still occurring. The deadlock seems to happen most often during an update, but that could just be a coincidence, as I've only traced it a couple of times. My questions are two-fold: 1) Is this actually an ITL deadlock? 2) If it is an ITL deadlock, what else can be done to avoid it? Cross-posted from Stack Overflow. Deadlocks are normally a programming problem, but ITL deadlocks relate directly to how Oracle writes to disk, so this may be an area where DBAs have more experience.

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• The Java Specialist: An Interview with Java Champion Heinz Kabutz

  - by Janice J. Heiss

  Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers. Originally published on blogs.oracle.com/javaone.

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• The Java Specialist: An Interview with Java Champion Heinz Kabutz

  - by Janice J. Heiss

  Dr. Heinz Kabutz is well known for his Java Specialists’ Newsletter, initiated in November 2000, where he displays his acute grasp of the intricacies of the Java platform for an estimated 70,000 readers; for his work as a consultant; and for his workshops and trainings at his home on the Island of Crete where he has lived since 2006 -- where he is known to curl up on the beach with his laptop to hack away, in between dips in the Mediterranean. Kabutz was born of German parents and raised in Cape Town, South Africa, where he developed a love of programming in junior high school through his explorations on a ZX Spectrum computer. He received a B.S. from the University of Cape Town, and at 25, a Ph.D., both in computer science. He will be leading a two-hour hands-on lab session, HOL6500 – “Finding and Solving Java Deadlocks,” at this year’s JavaOne that will explore what causes deadlocks and how to solve them. Q: Tell us about your JavaOne plans.A: I am arriving on Sunday evening and have just one hands-on-lab to do on Monday morning. This is the first time that a non-Oracle team is doing a HOL at JavaOne under Oracle's stewardship and we are all a bit nervous about how it will turn out. Oracle has been immensely helpful in getting us set up. I have a great team helping me: Kirk Pepperdine, Dario Laverde, Benjamin Evans and Martijn Verburg from jClarity, Nathan Reynolds from Oracle, Henri Tremblay of OCTO Technology and Jeff Genender of Savoir Technologies. Monday will be hard work, but after that, I will hopefully get to network with fellow Java experts, attend interesting sessions and just enjoy San Francisco. Oh, and my kids have already given me a shopping list of things to get, like a GoPro Hero 2 dive housing for shooting those nice videos of Crete. (That's me at the beginning diving down.) Q: What sessions are you attending that we should know about?A: Sometimes the most unusual sessions are the best. I avoid the "big names". They often are spread too thin with all their sessions, which makes it difficult for them to deliver what I would consider deep content. I also avoid entertainers who might be good at presenting but who do not say that much.In 2010, I attended a session by Vladimir Yaroslavskiy where he talked about sorting. Although he struggled to speak English, what he had to say was spectacular. There was hardly anybody in the room, having not heard of Vladimir before. To me that was the highlight of 2010. Funnily enough, he was supposed to speak with Joshua Bloch, but if you remember, Google cancelled. If Bloch has been there, the room would have been packed to capacity.Q: Give us an update on the Java Specialists’ Newsletter.A: The Java Specialists' Newsletter continues being read by an elite audience around the world. The apostrophe in the name is significant.  It is a newsletter for Java specialists. When I started it twelve years ago, I was trying to find non-obvious things in Java to write about. Things that would be interesting to an advanced audience.As an April Fool's joke, I told my readers in Issue 44 that subscribing would remain free, but that they would have to pay US$5 to US$7 depending on their geographical location. I received quite a few angry emails from that one. I would have not earned that much from unsubscriptions. Most readers stay for a very long time.After Oracle bought Sun, the Java community held its breath for about two years whilst Oracle was figuring out what to do with Java. For a while, we were quite concerned that there was not much progress shown by Oracle. My newsletter still continued, but it was quite difficult finding new things to write about. We have probably about 70,000 readers, which is quite a small number for a Java publication. However, our readers are the top in the Java industry. So I don't mind having "only" 70000 readers, as long as they are the top 0.7%.Java concurrency is a very important topic that programmers think they should know about, but often neglect to fully understand. I continued writing about that and made some interesting discoveries. For example, in Issue 165, I showed how we can get thread starvation with the ReadWriteLock. This was a bug in Java 5, which was corrected in Java 6, but perhaps a bit too much. Whereas we could get starvation of writers in Java 5, in Java 6 we could now get starvation of readers. All of these interesting findings make their way into my courseware to help companies avoid these pitfalls.Another interesting discovery was how polymorphism works in the Server HotSpot compiler in Issue 157 and Issue 158. HotSpot can inline methods from interfaces that have only one implementation class in the JVM. When a new subclass is instantiated and called for the first time, the JVM will undo the previous optimization and re-optimize differently.Here is a little memory puzzle for your readers: public class JavaMemoryPuzzle {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzle jmp = new JavaMemoryPuzzle();    jmp.f();  }}When you run this you will always get an OutOfMemoryError, even though the local variable data is no longer visible outside of the code block.So here comes the puzzle, that I'd like you to ponder a bit. If you very politely ask the VM to release memory, then you don't get an OutOfMemoryError: public class JavaMemoryPuzzlePolite {  private final int dataSize =      (int) (Runtime.getRuntime().maxMemory() * 0.6);  public void f() {    {      byte[] data = new byte[dataSize];    }    for(int i=0; i<10; i++) {      System.out.println("Please be so kind and release memory");    }    byte[] data2 = new byte[dataSize];  }  public static void main(String[] args) {    JavaMemoryPuzzlePolite jmp = new JavaMemoryPuzzlePolite();    jmp.f();    System.out.println("No OutOfMemoryError");  }}Why does this work? When I published this in my newsletter, I received over 400 emails from excited readers around the world, most of whom sent me the wrong explanation. After the 300th wrong answer, my replies became unfortunately a bit curt. Have a look at Issue 174 for a detailed explanation, but before you do, put on your thinking caps and try to figure it out yourself. Q: What do you think Java developers should know that they currently do not know?A: They should definitely get to know more about concurrency. It is a tough subject that most programmers try to avoid. Unfortunately we do come in contact with it. And when we do, we need to know how to protect ourselves and how to solve tricky system errors.Knowing your IDE is also useful. Most IDEs have a ton of shortcuts, which can make you a lot more productive in moving code around. Another thing that is useful is being able to read GC logs. Kirk Pepperdine has a great talk at JavaOne that I can recommend if you want to learn more. It's this: CON5405 – “Are Your Garbage Collection Logs Speaking to You?” Q: What are you looking forward to in Java 8?A: I'm quite excited about lambdas, though I must confess that I have not studied them in detail yet. Maurice Naftalin's Lambda FAQ is quite a good start to document what you can do with them. I'm looking forward to finding all the interesting bugs that we will now get due to lambdas obscuring what is really going on underneath, just like we had with generics.I am quite impressed with what the team at Oracle did with OpenJDK's performance. A lot of the benchmarks now run faster.Hopefully Java 8 will come with JSR 310, the Date and Time API. It still boggles my mind that such an important API has been left out in the cold for so long.What I am not looking forward to is losing perm space. Even though some systems run out of perm space, at least the problem is contained and they usually manage to work around it. In most cases, this is due to a memory leak in that region of memory. Once they bundle perm space with the old generation, I predict that memory leaks in perm space will be harder to find. More contracts for us, but also more pain for our customers.

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• VIM with iA Writer type formatting?

  - by Ambidex

  I've been Googling for a while now. I would like to have iA Writer-like (or a bit like StackExchange) formatting in Vim. Since I love the way it formats my texts, but I'm constantly pressing "w" to skip words because my experience with Vim. I would love to be able to have the same smart formatting in Vim. I did found a nice Vim plugin for getting Vim to toggle to big and clean font: https://github.com/honza/writer.vim But this still does not enable me to use the formatting: # Header 1 ## Header 2 *underline* **strong** etc... Besides all this above, I would not mind to have Vim like shortcuts in my iA writer app if it would not be possible to implement iA formatting in Vim. Edit: After a while of even more searching, I found out this type of formatting is called Markdown. I am starting to think there isn't really a good way to directly edit a Markdown file in Vim, because Vim is not able to make things display like that? I would really like to be able to use the movement shortcuts in combination of the nice formatting of Markdown and how it is displayed in iA Writer.

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