Search Results

Search found 659 results on 27 pages for 'safety'.

Page 23/27 | < Previous Page | 19 20 21 22 23 24 25 26 27  | Next Page >

  • 5.1 surround sound on Acer Aspire 5738ZG with Ubuntu 11.10

    - by kbargais_LV
    I got a problem with sound. I tried everything but no results. :( I got 3 sound ports. my daemon: # This file is part of PulseAudio. # # PulseAudio is free software; you can redistribute it and/or modify # it under the terms of the GNU Lesser General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # PulseAudio is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # General Public License for more details. # # You should have received a copy of the GNU Lesser General Public License # along with PulseAudio; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 # USA. ## Configuration file for the PulseAudio daemon. See pulse-daemon.conf(5) for ## more information. Default values are commented out. Use either ; or # for ## commenting. ; daemonize = no ; fail = yes ; allow-module-loading = yes ; allow-exit = yes ; use-pid-file = yes ; system-instance = no ; local-server-type = user ; enable-shm = yes ; shm-size-bytes = 0 # setting this 0 will use the system-default, usually 64 MiB ; lock-memory = no ; cpu-limit = no ; high-priority = yes ; nice-level = -11 ; realtime-scheduling = yes ; realtime-priority = 5 ; exit-idle-time = 20 ; scache-idle-time = 20 ; dl-search-path = (depends on architecture) ; load-default-script-file = yes ; default-script-file = /etc/pulse/default.pa ; log-target = auto ; log-level = notice ; log-meta = no ; log-time = no ; log-backtrace = 0 resample-method = speex-float-1 ; enable-remixing = yes ; enable-lfe-remixing = no flat-volumes = no ; rlimit-fsize = -1 ; rlimit-data = -1 ; rlimit-stack = -1 ; rlimit-core = -1 ; rlimit-as = -1 ; rlimit-rss = -1 ; rlimit-nproc = -1 ; rlimit-nofile = 256 ; rlimit-memlock = -1 ; rlimit-locks = -1 ; rlimit-sigpending = -1 ; rlimit-msgqueue = -1 ; rlimit-nice = 31 ; rlimit-rtprio = 9 ; rlimit-rttime = 1000000 ; default-sample-format = s16le ; default-sample-rate = 44100 ; default-sample-channels = 6 ; default-channel-map = front-left,front-right default-fragments = 8 default-fragment-size-msec = 10 ; enable-deferred-volume = yes ; deferred-volume-safety-margin-usec = 8000 ; deferred-volume-extra-delay-usec = 0

    Read the article

  • Nest reinvents smoke detectors. Introduces smart and talking smoke detector that keeps quite when you wave

    - by Gopinath
    Nest, the leading smart thermostat maker has introduced a smart home device today- Nest Protect, a smart, talking smoke & carbon monoxide detector that can quite when you wave your hand. Less annoyances and more intelligence Smoke detectors are around for hundreds of years and playing a major role in providing safety from fire accidents at home. But the technology of these devices is stale and there is no major innovation for the past several years. With the introduction of Nest Protect, the landscape of smoke detectors is all set to change just like how Nest thermostat redefined the industry two years ago. Nest Protect is internet enabled and equipped with motion- and smoke-detection sensors so that when it starts beeping you can silence it by waving hand instead of doing circus feats to turn off the alarm. Everyone who cooks in a home equipped with smoke detector would know how annoying it is to turn off sensitive smoke detectors that goes off control quite often. Apart from addressing the annoyances of regular smoke detector, Nest Protect has talking capabilities. It can alert users with clear & actionable instructions when it detects a danger. Instead of harsh beeps it actually speak to you so you know what is happening. It will tell you what smoke it has detected and in which room it is detected. Multiple Nest Protects installed in a home can communicate with each other. Lets say that there is a smoke in bed room, the Nest Protect installed in bed room shares this information to all Nest Protects installed in the home and your kitchen device can alert you that there is a smoke in bed room. There is an App for that The internet enabled Nest Protect has an app to view its status and various alerts. When the Protect is running on low battery it alerts you to replace them soon. If there is a smoke at home and you are away, you will get message alerts. The app works on all major smartphones as well as tablets. Auto shuts down gas furnaces/heaters on smoke Apart from forming a network with other Nest Protect devices installed at home, they can also communicate with Nest Thermostat if it is installed. When carbon monoxide is detected it can shut off your gas furnace automatically. Also with the help of motion detectors it improves Nest Thermostat’s auto-away functionality. It looks elegant and costs a lot more than a regular smoke detector Just like Nest Thermostat, Nest Protect is elegant and adorable. You just fall in love with it the moment you see it. It’s another master piece from the designer of Apple’s iPod. All is good with the Nest Protect, except the price!! It costs whooping $129, which is almost 4 times more expensive than the best selling conventional thermostats available at $30. A single bed room apartment would require at least 3 detectors and it costs around $390 to install Nest Protects compared to 90$ required for conventional smoke detectors. Though Nest Thermostat is an expensive one compared to conventional thermostats, it offered great savings through its intelligent auto-away feature. Users were able to able to see returns on their investments. If Nest Protect also can provide good return on investment the it will be very successful.

    Read the article

  • Impressions on jQuery Mobile

    - by Jeff
    For the uninitiated, jQuery Mobile is a sweet little client framework that turns regular HTML into something more touch and mobile friendly. It results in a user interface that has bigger targets, rounded corners and simple skinning capability. When it was announced that ASP.NET MVC 4 would include support for a mobile-sensitive view engine, offering up alternate views for clients that fit the mobile profile, I was all over that. Combined with jQuery Mobile, it brought a chance to do some experimentation. I blitzed through the views in POP Forums and converted them all to mobile views. (For the curious, this first pass can be found here on CodePlex, while a more recent update that uses RC 2 of jQuery Mobile v1.1.0 is running on the demo site.) Initially, it was kind of a mixed bag. The jQuery demo site also acts as documentation, and it’s reasonably complete. I had no problem getting up a lot of basic views quickly, splitting out portions of some pages as subpages that they quickly load in. The default behavior in the older version was to slide the pages in, which looked a little weird when you were using a back button. They’ve since changed it so the default transition is a fade in/out. Because you’re dealing with Web pages, I don’t think anyone is really under the illusion that you’re not using a native app, so I don’t know that this matters. I’ve tested extensively on iPad and Windows Phone, and to be honest, I’ve encountered a lot of issues. On Windows Phone, there is some kind of inconsistency that prevents the proper respect for the viewport settings. The text background on text fields (for labeling) doesn’t work, either. On both platforms, certain in-DOM page navigation links work only half of the time. Is this an issue of user error? Probably, but that’s what’s frustrating about it. Most of what you accomplish with this framework involves decorating various elements with CSS classes. There isn’t any design-time safety to speak of to make sure that you’re doing it right. I think the issues can be overcome, but there are some trade-offs to consider. The first is download size. Yes, the scripts and CSS do get cached, but that first hit will cost nearly 40k for the mobile parts. That’s still a lot when you’re on some crappy AT&T EDGE network, or hotel Wi-Fi. Then you have to ask yourself, do you really want your app to look like it’s native to iOS? I’m not saying that’s a bad thing, because consistent UI is good, but you will end up feeling a whole lot of sameness, and maybe you don’t want that. I did some experimentation to try and Metro-ize the jQuery Mobile theme, and it’s kind of a mixed bag. It mostly works, but you get some weirdness on badges and with buttons that I’m not crazy about. It probably just means you need to keep tweaking. At this point, I’m a little torn about whether or not I’ll use it for POP Forums or one of the sites I’m working on. The benefits are pretty strong, but figuring out where I’m doing it wrong is proving a little time consuming.

    Read the article

  • Create a Remote Git Repository from an Existing XCode Repository

    - by codeWithoutFear
    Introduction Distributed version control systems (VCS’s), like Git, provide a rich set of features for managing source code.  Many development tools, including XCode, provide built-in support for various VCS’s.  These tools provide simple configuration with limited customization to get you up and running quickly while still providing the safety net of basic version control. I hate losing (and re-doing) work.  I have OCD when it comes to saving and versioning source code.  Save early, save often, and commit to the VCS often.  I also hate merging code.  Smaller and more frequent commits enable me to minimize merge time and effort as well. The work flow I prefer even for personal exploratory projects is: Make small local changes to the codebase to create an incrementally improved (and working) system. Commit these changes to the local repository.  Local repositories are quick to access, function even while offline, and provides the confidence to continue making bold changes to the system.  After all, I can easily recover to a recent working state. Repeat 1 & 2 until the codebase contains “significant” functionality and I have connectivity to the remote repository. Push the accumulated changes to the remote repository.  The smaller the change set, the less likely extensive merging will be required.  Smaller is better, IMHO. The remote repository typically has a greater degree of fault tolerance and active management dedicated to it.  This can be as simple as a network share that is backed up nightly or as complex as dedicated hardware with specialized server-side processing and significant administrative monitoring. XCode’s out-of-the-box Git integration enables steps 1 and 2 above.  Time Machine backups of the local repository add an additional degree of fault tolerance, but do not support collaboration or take advantage of managed infrastructure such as on-premises or cloud-based storage. Creating a Remote Repository These are the steps I use to enable the full workflow identified above.  For simplicity the “remote” repository is created on the local file system.  This location could easily be on a mounted network volume. Create a Test Project My project is called HelloGit and is located at /Users/Don/Dev/HelloGit.  Be sure to commit all outstanding changes.  XCode always leaves a single changed file for me after the project is created and the initial commit is submitted. Clone the Local Repository We want to clone the XCode-created Git repository to the location where the remote repository will reside.  In this case it will be /Users/Don/Dev/RemoteHelloGit. Open the Terminal application. Clone the local repository to the remote repository location: git clone /Users/Don/Dev/HelloGit /Users/Don/Dev/RemoteHelloGit Convert the Remote Repository to a Bare Repository The remote repository only needs to contain the Git database.  It does not need a checked out branch or local files. Go to the remote repository folder: cd /Users/Don/Dev/RemoteHelloGit Indicate the repository is “bare”: git config --bool core.bare true Remove files, leaving the .git folder: rm -R * Remove the “origin” remote: git remote rm origin Configure the Local Repository The local repository should reference the remote repository.  The remote name “origin” is used by convention to indicate the originating repository.  This is set automatically when a repository is cloned.  We will use the “origin” name here to reflect that relationship. Go to the local repository folder: cd /Users/Don/Dev/HelloGit Add the remote: git remote add origin /Users/Don/Dev/RemoteHelloGit Test Connectivity Any changes made to the local Git repository can be pushed to the remote repository subject to the merging rules Git enforces. Create a new local file: date > date.txt /li> Add the new file to the local index: git add date.txt Commit the change to the local repository: git commit -m "New file: date.txt" Push the change to the remote repository: git push origin master Now you can save, commit, and push/pull to your OCD hearts’ content! Code without fear! --Don

    Read the article

  • The Power of Goals

    - by BuckWoody
    Every year we read blogs, articles, magazines, hear news stories and blurbs on making New Year’s Resolutions. Well, I for one don’t do that. I do something else. Each year, on January 1, my wife, daughter and I get up early - like before 6:00 A.M. - and find a breakfast place that’s open. When I used to live in Safety Harbor, Florida, that was the “Paradise Café”, which has some of the best waffles around…but I digress. We find that restaurant and have a great breakfast while everyone else is recuperating from the night before. And we bring along a worn leather book that we’ve been writing in since my daughter wasn’t even old enough to read. It’s our book of Goals. A resolution, as it is purely defined, is a decision to change, stop or start an action. It has a sense of continuance, and that’s the issue. Some people decide things like “I’m going to lose weight” or “I’m going to spend more time with my family or hobby”. But a goal is different. A goal tends to have a defined start and end point. It’s something that can be measured. So each year on January 1 we sit down with the little leather book and we make a few - and only a few - individual and family goals. Sometimes it’s to exercise three times a week at the gym, sometimes it’s to save a certain percentage of income, and sometimes it’s to give away some of our possessions or to help someone we know in a specific way. Each person is responsible for their own goals - coming up with them, and coming up with a plan to meet them. Then we write it down in the little leather book. But it doesn’t end there. Each month, we grab the little leather book and read out the goals from that year to each person with a question or two: How are you doing on your goal? And what are you doing about reaching it? Can I help? Am I helping? At the end of the year, we put a checkmark by the goals we reached, and an X by the ones we didn’t. There’s no judgment, there’s no statements, each person is just expected to handle the success or failure in their own way. We also have family goals, and those we work on together. This might seem a little “corny” to some people. “I don’t need to write goals down” they say, “I keep track in my head of the things I do all the time. That’s silly.” But let me give you a little challenge: find a book, get with your family, and write down the things you want to do by the next January 1. Each month, look at the book. You can make goals for your career, your education, your spiritual side, your family, whatever. But if you make your goals realistic, think them through, and think about how you will achieve them, you will be surprised by the power of written goals.

    Read the article

  • 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.

    Read the article

  • Why do I need two Instances in Windows Azure?

    - by BuckWoody
    Windows Azure as a Platform as a Service (PaaS) means that there are various components you can use in it to solve a problem: Compute “Roles” - Computers running an OS and optionally IIS - you can have more than one "Instance" of a given Role Storage - Blobs, Tables and Queues for Storage Other Services - Things like the Service Bus, Azure Connection Services, SQL Azure and Caching It’s important to understand that some of these services are Stateless and others maintain State. Stateless means (at least in this case) that a system might disappear from one physical location and appear elsewhere. You can think of this as a cashier at the front of a store. If you’re in line, a cashier might take his break, and another person might replace him. As long as the order proceeds, you as the customer aren’t really affected except for the few seconds it takes to change them out. The cashier function in this example is stateless. The Compute Role Instances in Windows Azure are Stateless. To upgrade hardware, because of a fault or many other reasons, a Compute Role's Instance might stop on one physical server, and another will pick it up. This is done through the controlling fabric that Windows Azure uses to manage the systems. It’s important to note that storage in Azure does maintain State. Your data will not simply disappear - it is maintained - in fact, it’s maintained three times in a single datacenter and all those copies are replicated to another for safety. Going back to our example, storage is similar to the cash register itself. Even though a cashier leaves, the record of your payment is maintained. So if a Compute Role Instance can disappear and re-appear, the things running on that first Instance would stop working. If you wrote your code in a Stateless way, then another Role Instance simply re-starts that transaction and keeps working, just like the other cashier in the example. But if you only have one Instance of a Role, then when the Role Instance is re-started, or when you need to upgrade your own code, you can face downtime, since there’s only one. That means you should deploy at least two of each Role Instance not only for scale to handle load, but so that the first “cashier” has someone to replace them when they disappear. It’s not just a good idea - to gain the Service Level Agreement (SLA) for our uptime in Azure it’s a requirement. We point this out right in the Management Portal when you deploy the application: (Click to enlarge) When you deploy a Role Instance you can also set the “Upgrade Domain”. Placing Roles on separate Upgrade Domains means that you have a continuous service whenever you upgrade (more on upgrades in another post) - the process looks like this for two Roles. This example covers the scenario for upgrade, so you have four roles total - One Web and one Worker running the "older" code, and one of each running the new code. In all those Roles you want at least two instances, and this example shows that you're covered for High Availability and upgrade paths: The take-away is this - always plan for forward-facing Roles to have at least two copies. For Worker Roles that do background processing, there are ways to architect around this number, but it does affect the SLA if you have only one.

    Read the article

  • Caching factory design

    - by max
    I have a factory class XFactory that creates objects of class X. Instances of X are very large, so the main purpose of the factory is to cache them, as transparently to the client code as possible. Objects of class X are immutable, so the following code seems reasonable: # module xfactory.py import x class XFactory: _registry = {} def get_x(self, arg1, arg2, use_cache = True): if use_cache: hash_id = hash((arg1, arg2)) if hash_id in _registry: return _registry[hash_id] obj = x.X(arg1, arg2) _registry[hash_id] = obj return obj # module x.py class X: # ... Is it a good pattern? (I know it's not the actual Factory Pattern.) Is there anything I should change? Now, I find that sometimes I want to cache X objects to disk. I'll use pickle for that purpose, and store as values in the _registry the filenames of the pickled objects instead of references to the objects. Of course, _registry itself would have to be stored persistently (perhaps in a pickle file of its own, in a text file, in a database, or simply by giving pickle files the filenames that contain hash_id). Except now the validity of the cached object depends not only on the parameters passed to get_x(), but also on the version of the code that created these objects. Strictly speaking, even a memory-cached object could become invalid if someone modifies x.py or any of its dependencies, and reloads it while the program is running. So far I ignored this danger since it seems unlikely for my application. But I certainly cannot ignore it when my objects are cached to persistent storage. What can I do? I suppose I could make the hash_id more robust by calculating hash of a tuple that contains arguments arg1 and arg2, as well as the filename and last modified date for x.py and every module and data file that it (recursively) depends on. To help delete cache files that won't ever be useful again, I'd add to the _registry the unhashed representation of the modified dates for each record. But even this solution isn't 100% safe since theoretically someone might load a module dynamically, and I wouldn't know about it from statically analyzing the source code. If I go all out and assume every file in the project is a dependency, the mechanism will still break if some module grabs data from an external website, etc.). In addition, the frequency of changes in x.py and its dependencies is quite high, leading to heavy cache invalidation. Thus, I figured I might as well give up some safety, and only invalidate the cache only when there is an obvious mismatch. This means that class X would have a class-level cache validation identifier that should be changed whenever the developer believes a change happened that should invalidate the cache. (With multiple developers, a separate invalidation identifier is required for each.) This identifier is hashed along with arg1 and arg2 and becomes part of the hash keys stored in _registry. Since developers may forget to update the validation identifier or not realize that they invalidated existing cache, it would seem better to add another validation mechanism: class X can have a method that returns all the known "traits" of X. For instance, if X is a table, I might add the names of all the columns. The hash calculation will include the traits as well. I can write this code, but I am afraid that I'm missing something important; and I'm also wondering if perhaps there's a framework or package that can do all of this stuff already. Ideally, I'd like to combine in-memory and disk-based caching.

    Read the article

  • The Future of Air Travel: Intelligence and Automation

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

    Read the article

  • RemoveHandler Issues with Custom Events

    - by Jeff Certain
    This is a case of things being more complicated that I thought they should be. Since it took a while to figure this one out, I thought it was worth explaining and putting all of the pieces to the answer in one spot. Let me set the stage. Architecturally, I have the notion of generic producers and consumers. These put items onto, and remove items from, a queue. This provides a generic, thread-safe mechanism to load balance the creation and processing of work items in our application. Part of the IProducer(Of T) interface is: 1: Public Interface IProducer(Of T) 2: Event ItemProduced(ByVal sender As IProducer(Of T), ByVal item As T) 3: Event ProductionComplete(ByVal sender As IProducer(Of T)) 4: End Interface Nothing sinister there, is there? In order to simplify our developers’ lives, I wrapped the queue with some functionality to manage the produces and consumers. Since the developer can specify the number of producers and consumers that are spun up, the queue code manages adding event handlers as the producers and consumers are instantiated. Now, we’ve been having some memory leaks and, in order to eliminate the possibility that this was caused by weak references to event handles, I wanted to remove them. This is where it got dicey. My first attempt looked like this: 1: For Each producer As P In Producers 2: RemoveHandler producer.ItemProduced, AddressOf ItemProducedHandler 3: RemoveHandler producer.ProductionComplete, AddressOf ProductionCompleteHandler 4: producer.Dispose() 5: Next What you can’t see in my posted code are the warnings this caused. The 'AddressOf' expression has no effect in this context because the method argument to 'AddressOf' requires a relaxed conversion to the delegate type of the event. Assign the 'AddressOf' expression to a variable, and use the variable to add or remove the method as the handler.  Now, what on earth does that mean? Well, a quick Bing search uncovered a whole bunch of talk about delegates. The first solution I found just changed all parameters in the event handler to Object. Sorry, but no. I used generics precisely because I wanted type safety, not because I wanted to use Object. More searching. Eventually, I found this forum post, where Jeff Shan revealed a missing piece of the puzzle. The other revelation came from Lian_ZA in this post. However, these two only hinted at the solution. Trying some of what they suggested led to finally getting an invalid cast exception that revealed the existence of ItemProducedEventHandler. Hold on a minute! I didn’t create that delegate. There’s nothing even close to that name in my code… except the ItemProduced event in the interface. Could it be? Naaaaah. Hmmm…. Well, as it turns out, there is a delegate created by the compiler for each event. By explicitly creating a delegate that refers to the method in question, implicitly cast to the generated delegate type, I was able to remove the handlers: 1: For Each producer As P In Producers 2: Dim _itemProducedHandler As IProducer(Of T).ItemProducedEventHandler = AddressOf ItemProducedHandler 3: RemoveHandler producer.ItemProduced, _itemProducedHandler 4:  5: Dim _productionCompleteHandler As IProducer(Of T).ProductionCompleteEventHandler = AddressOf ProductionCompleteHandler 6: RemoveHandler producer.ProductionComplete, _productionCompleteHandler 7: producer.Dispose() 8: Next That’s “all” it took to finally be able to remove the event handlers and maintain type-safe code. Hopefully, this will save you the same challenges I had in trying to figure out how to fix this issue!

    Read the article

  • Openmatics Revolutionizes Fleet Management with Standards-Based Vehicle Telematics Platform

    - by Michael Snow
    Openmatics s.r.o. was founded in 2010 as a subsidiary of ZF Friedrichshafen AG, a global player in driveline and chassis technology. Oracle Customer:  Openmatics s.r.o.Location:  Pilsen, Czech RepublicIndustry:  AutomotiveEmployees:  70 Its goal was to develop and operate a flexible, open telematics platform for automotive applications, which is independent from vehicle and component suppliers—recognizing that the fragmented telematics market was not meeting today’s fleet management needs. Openmatics provides a rich product portfolio, and customers can extend the platform, as required, to meet their needs. Partners and third-parties can develop their own applications using the Openmatics’ software development kit and can sell them via the Openmatics app shop.ZF Friedrichshafen AG is a global player in driveline and chassis technology. With 121 production companies and 650 service partners in 26 countries, ZF is among the top 10 largest automotive suppliers worldwide. Founded in 1915 to develop and produce transmissions for airships and vehicles, the group’s product offerings now include transmissions and steering systems as well as chassis components and complete axle systems and modules.  A word from Openmatics s.r.o.  “Oracle WebCenter Portal, together with the underlying Oracle Application Development Framework, provided the fundamental infrastructure for the Openmatics platform. Fleet managers can now reduce fuel consumption and operating costs, and more efficiently manage vehicle usage, maintenance, and safety. The standards-based platform allows third-party suppliers to deploy their own vehicle telematics services as Openmatics apps and creates a de facto standard for the automotive industry, independent from a single manufacturer or service provider.” – Gero Strobel, Head of Development, Openmatics s.r.o. Challenges Create an industry standard for vehicle telematics by establishing a customizable platform that enables access to telematics information, such as current and past fuel consumption, through a web browser to better meet automotive market and customer needs Reduce fleet-management costs by eliminating the need to invest in isolated telematics hardware and software solutions per vehicle brand and vehicle component manufacturer Establish an open platform where third-party providers—such as original equipment manufacturers (OEM), insurers, fleet operators, and individual developers—can deploy their own vehicle telematics services Allow users to purchase targeted telematics services as single apps to reduce costs and ensure rapid growth of telematics services available on the platform Enable users to configure their telematics apps with ease to make sure the platform meets individual fleet management requirements, such as analyzing past and current fuel consumption of a truck fleet Solutions Deployed Oracle WebCenter Portal as a foundation for Openmatics, a standards-based automotive telematics platform that provides next-generation fleet management with unified digital communication from and to vehicles on the move Used Oracle Application Development Framework as the development framework for Oracle WebCenter Portal’s components and services, providing developers with ready-to-use software development kits with application programming interfaces, design templates, and visual tools that accelerated time to market Used Oracle Enterprise Pack for Eclipse to simplify telematics application development in Java Enabled fleet monitoring by recording vehicle data—such as fuel consumption information—through onboard units, delivering the information to Oracle Database, and making it accessible through a customizable app portfolio on any web browser Stored vehicle telematics data—sent as encrypted information—in Oracle Database, ensuring data integrity and immediate availability for the platform’s telematics applications Enabled a wide range of telematics services suppliers, from vehicle component manufacturers to fleet application developers, to offer vehicle telematics services on the Openmatics platform, ensuring platform independence from OEMs Provided Openmatics customers with the means to individually select the automotive telematics services that are relevant to their business requirements, eliminating the need to pay for superfluous information and reducing fleet management costs Oracle Products & Services Oracle Application Development Framework Oracle WebCenter Portal Oracle SOA Suite Oracle Enterprise Pack for Eclipse Oracle Database Oracle Consulting &amp;amp;amp;amp;amp;amp;amp;&amp;amp;amp;amp;amp;lt;span id=&amp;amp;amp;amp;amp;quot;XinhaEditingPostion&amp;amp;amp;amp;amp;quot;&amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;lt;/span&amp;amp;amp;amp;amp;gt;amp;&amp;amp;amp;amp;amp;amp;lt;span id=&amp;amp;amp;amp;amp;amp;quot;XinhaEditingPostion&amp;amp;amp;amp;amp;amp;quot;&amp;amp;amp;amp;amp;amp;gt;&amp;amp;amp;amp;amp;amp;lt;/span&amp;amp;amp;amp;amp;amp;gt;lt;p&amp;amp;amp;amp;amp;amp;amp;amp;gt; &amp;amp;amp;amp;amp;amp;amp;amp;lt;/p&amp;amp;amp;amp;amp;amp;amp;amp;gt;

    Read the article

  • ConcurrentDictionary<TKey,TValue> used with Lazy<T>

    - by Reed
    In a recent thread on the MSDN forum for the TPL, Stephen Toub suggested mixing ConcurrentDictionary<T,U> with Lazy<T>.  This provides a fantastic model for creating a thread safe dictionary of values where the construction of the value type is expensive.  This is an incredibly useful pattern for many operations, such as value caches. The ConcurrentDictionary<TKey, TValue> class was added in .NET 4, and provides a thread-safe, lock free collection of key value pairs.  While this is a fantastic replacement for Dictionary<TKey, TValue>, it has a potential flaw when used with values where construction of the value class is expensive. The typical way this is used is to call a method such as GetOrAdd to fetch or add a value to the dictionary.  It handles all of the thread safety for you, but as a result, if two threads call this simultaneously, two instances of TValue can easily be constructed. If TValue is very expensive to construct, or worse, has side effects if constructed too often, this is less than desirable.  While you can easily work around this with locking, Stephen Toub provided a very clever alternative – using Lazy<TValue> as the value in the dictionary instead. This looks like the following.  Instead of calling: MyValue value = dictionary.GetOrAdd( key, () => new MyValue(key)); .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: consolas, "Courier New", courier, monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } We would instead use a ConcurrentDictionary<TKey, Lazy<TValue>>, and write: MyValue value = dictionary.GetOrAdd( key, () => new Lazy<MyValue>( () => new MyValue(key))) .Value; This simple change dramatically changes how the operation works.  Now, if two threads call this simultaneously, instead of constructing two MyValue instances, we construct two Lazy<MyValue> instances. However, the Lazy<T> class is very cheap to construct.  Unlike “MyValue”, we can safely afford to construct this twice and “throw away” one of the instances. We then call Lazy<T>.Value at the end to fetch our “MyValue” instance.  At this point, GetOrAdd will always return the same instance of Lazy<MyValue>.  Since Lazy<T> doesn’t construct the MyValue instance until requested, the actual MyClass instance returned is only constructed once.

    Read the article

  • Learn Many Languages

    - by Jeff Foster
    My previous blog, Deliberate Practice, discussed the need for developers to “sharpen their pencil” continually, by setting aside time to learn how to tackle problems in different ways. However, the Sapir-Whorf hypothesis, a contested and somewhat-controversial concept from language theory, seems to hold reasonably true when applied to programming languages. It states that: “The structure of a language affects the ways in which its speakers conceptualize their world.” If you’re constrained by a single programming language, the one that dominates your day job, then you only have the tools of that language at your disposal to think about and solve a problem. For example, if you’ve only ever worked with Java, you would never think of passing a function to a method. A good developer needs to learn many languages. You may never deploy them in production, you may never ship code with them, but by learning a new language, you’ll have new ideas that will transfer to your current “day-job” language. With the abundant choices in programming languages, how does one choose which to learn? Alan Perlis sums it up best. “A language that doesn‘t affect the way you think about programming is not worth knowing“ With that in mind, here’s a selection of languages that I think are worth learning and that have certainly changed the way I think about tackling programming problems. Clojure Clojure is a Lisp-based language running on the Java Virtual Machine. The unique property of Lisp is homoiconicity, which means that a Lisp program is a Lisp data structure, and vice-versa. Since we can treat Lisp programs as Lisp data structures, we can write our code generation in the same style as our code. This gives Lisp a uniquely powerful macro system, and makes it ideal for implementing domain specific languages. Clojure also makes software transactional memory a first-class citizen, giving us a new approach to concurrency and dealing with the problems of shared state. Haskell Haskell is a strongly typed, functional programming language. Haskell’s type system is far richer than C# or Java, and allows us to push more of our application logic to compile-time safety. If it compiles, it usually works! Haskell is also a lazy language – we can work with infinite data structures. For example, in a board game we can generate the complete game tree, even if there are billions of possibilities, because the values are computed only as they are needed. Erlang Erlang is a functional language with a strong emphasis on reliability. Erlang’s approach to concurrency uses message passing instead of shared variables, with strong support from both the language itself and the virtual machine. Processes are extremely lightweight, and garbage collection doesn’t require all processes to be paused at the same time, making it feasible for a single program to use millions of processes at once, all without the mental overhead of managing shared state. The Benefits of Multilingualism By studying new languages, even if you won’t ever get the chance to use them in production, you will find yourself open to new ideas and ways of coding in your main language. For example, studying Haskell has taught me that you can do so much more with types and has changed my programming style in C#. A type represents some state a program should have, and a type should not be able to represent an invalid state. I often find myself refactoring methods like this… void SomeMethod(bool doThis, bool doThat) { if (!(doThis ^ doThat)) throw new ArgumentException(“At least one arg should be true”); if (doThis) DoThis(); if (doThat) DoThat(); } …into a type-based solution, like this: enum Action { DoThis, DoThat, Both }; void SomeMethod(Action action) { if (action == Action.DoThis || action == Action.Both) DoThis(); if (action == Action.DoThat || action == Action.Both) DoThat(); } At this point, I’ve removed the runtime exception in favor of a compile-time check. This is a trivial example, but is just one of many ideas that I’ve taken from one language and implemented in another.

    Read the article

  • How do I get 5.1 surround sound working on an Acer Aspire 5738ZG?

    - by kbargais_LV
    I got a problem with sound. I tried everything but no results. :( I got 3 sound ports. my daemon: # This file is part of PulseAudio. # # PulseAudio is free software; you can redistribute it and/or modify # it under the terms of the GNU Lesser General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # PulseAudio is distributed in the hope that it will be useful, but # WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # General Public License for more details. # # You should have received a copy of the GNU Lesser General Public License # along with PulseAudio; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 # USA. ## Configuration file for the PulseAudio daemon. See pulse-daemon.conf(5) for ## more information. Default values are commented out. Use either ; or # for ## commenting. ; daemonize = no ; fail = yes ; allow-module-loading = yes ; allow-exit = yes ; use-pid-file = yes ; system-instance = no ; local-server-type = user ; enable-shm = yes ; shm-size-bytes = 0 # setting this 0 will use the system-default, usually 64 MiB ; lock-memory = no ; cpu-limit = no ; high-priority = yes ; nice-level = -11 ; realtime-scheduling = yes ; realtime-priority = 5 ; exit-idle-time = 20 ; scache-idle-time = 20 ; dl-search-path = (depends on architecture) ; load-default-script-file = yes ; default-script-file = /etc/pulse/default.pa ; log-target = auto ; log-level = notice ; log-meta = no ; log-time = no ; log-backtrace = 0 resample-method = speex-float-1 ; enable-remixing = yes ; enable-lfe-remixing = no flat-volumes = no ; rlimit-fsize = -1 ; rlimit-data = -1 ; rlimit-stack = -1 ; rlimit-core = -1 ; rlimit-as = -1 ; rlimit-rss = -1 ; rlimit-nproc = -1 ; rlimit-nofile = 256 ; rlimit-memlock = -1 ; rlimit-locks = -1 ; rlimit-sigpending = -1 ; rlimit-msgqueue = -1 ; rlimit-nice = 31 ; rlimit-rtprio = 9 ; rlimit-rttime = 1000000 ; default-sample-format = s16le ; default-sample-rate = 44100 ; default-sample-channels = 6 ; default-channel-map = front-left,front-right default-fragments = 8 default-fragment-size-msec = 10 ; enable-deferred-volume = yes ; deferred-volume-safety-margin-usec = 8000 ; deferred-volume-extra-delay-usec = 0

    Read the article

  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

    Read the article

  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

    Read the article

  • Best available technology for layered disk cache in linux

    - by SpliFF
    I've just bought a 6-core Phenom with 16G of RAM. I use it primarily for compiling and video encoding (and occassional web/db). I'm finding all activities get disk-bound and I just can't keep all 6 cores fed. I'm buying an SSD raid to sit between the HDD and tmpfs. I want to setup a "layered" filesystem where reads are cached on tmpfs but writes safely go through to the SSD. I want files (or blocks) that haven't been read lately on the SSD to then be written back to a HDD using a compressed FS or block layer. So basically reads: - Check tmpfs - Check SSD - Check HD And writes: - Straight to SSD (for safety), then tmpfs (for speed) And periodically, or when space gets low: - Move least frequently accessed files down one layer. I've seen a few projects of interest. CacheFS, cachefsd, bcache seem pretty close but I'm having trouble determining which are practical. bcache seems a little risky (early adoption), cachefs seems tied to specific network filesystems. There are "union" projects unionfs and aufs that let you mount filesystems over each other (USB device over a DVD usually) but both are distributed as a patch and I get the impression this sort of "transparent" mounting was going to become a kernel feature rather than a FS. I know the kernel has a built-in disk cache but it doesn't seem to work well with compiling. I see a 20x speed improvement when I move my source files to tmpfs. I think it's because the standard buffers are dedicated to a specific process and compiling creates and destroys thousands of processes during a build (just guessing there). It looks like I really want those files precached. I've read tmpfs can use virtual memory. In that case is it practical to create a giant tmpfs with swap on the SSD? I don't need to boot off the resulting layered filesystem. I can load grub, kernel and initrd from elsewhere if needed. So that's the background. The question has several components I guess: Recommended FS and/or block layer for the SSD and compressed HDD. Recommended mkfs parameters (block size, options etc...) Recommended cache/mount technology to bind the layers transparently Required mount parameters Required kernel options / patches, etc..

    Read the article

  • Bidirectional real-time sync of large file tree between two distant linux servers

    - by dlo
    By large file tree I mean about 200k files, and growing all the time. A relatively small number of files are being changed in any given hour though. By bidirectional I mean that changes may occur on either server and need to be pushed to the other, so rsync doesn't seem appropriate. By distant I mean that the servers are both in data centers, but geographically remote from each other. Currently there are only 2 servers, but that may expand over time. By real-time, it's ok for there to be a little latency between syncing, but running a cron every 1-2 minutes doesn't seem right, since a very small fraction of files may change in any given hour, let alone minute. EDIT: This is running on VPS's so I might be limited on the kinds of kernel-level stuff I can do. Also, the VPS's are not resource-rich, so I'd shy away from solutions that require lots of ram (like Gluster?). What's the best / most "accepted" approach to get this done? This seems like it would be a common need, but I haven't been able to find a generally accepted approach yet, which was surprising. (I'm seeking the safety of the masses. :) I've come across lsyncd to trigger a sync at the filesystem change level. That seems clever though not super common, and I'm a bit confused by the various lsyncd approaches. There's just using lsyncd with rsync, but it seems this could be fragile for bidirectionality since rsync doesn't have a notion of memory (eg- to know whether a deleted file on A should be deleted on B or whether it's a new file on B that should be copied to A). lipsync appears to be just a lsyncd+rsync implementation, right? Then there's using lsyncd with csync2, like this: http://www.axivo.com/community/threads/lightning-fast-synchronization-with-csync2-and-lsyncd.121/ ... I'm leaning towards this approach, but csync2 is a little quirky, though I did do a successful test of it. I'm mostly concerned that I haven't been able to find a lot of community confirmation of this method. People on here seem to like Unison a lot, but it seems that it is no longer under active development and it's not clear that it has an automatic trigger like lsyncd. I've seen Gluster mentioned, but maybe overkill for what I need? UPDATE: fyi- I ended up going with the original solution I mentioned: lsyncd+csync2. It seems to work quite well, and I like the architectural approach of having the servers be very loosely joined, so that each server can operate indefinitely on its own regardless of the link quality between them.

    Read the article

  • Why are people trying to connect to me network on TCP port 445?

    - by Solignis
    I was playing with my new syslog server and had my m0n0wall firewall logs forwarded as a test, I noticed a bunch of recent firewall log entries that say that it blocked other WAN IPs from my ISP (I checked) from connecting to me on TCP port 445. Why would a random computer be trying to connect to me on a port apperently used for Windows SMB shares? Just internet garbage? A port scan? I am just curious. here is what I am seeing Mar 15 23:38:41 gateway/gateway ipmon[121]: 23:38:40.614422 fxp0 @0:19 b 98.82.198.238,60653 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN broadcast Mar 15 23:38:42 gateway/gateway ipmon[121]: 23:38:41.665571 fxp0 @0:19 b 98.82.198.238,60665 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN Mar 15 23:38:43 gateway/gateway ipmon[121]: 23:38:43.165622 fxp0 @0:19 b 98.82.198.238,60670 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN broadcast Mar 15 23:38:44 gateway/gateway ipmon[121]: 23:38:43.614524 fxp0 @0:19 b 98.82.198.238,60653 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN broadcast Mar 15 23:38:44 gateway/gateway ipmon[121]: 23:38:43.808856 fxp0 @0:19 b 98.82.198.238,60665 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN Mar 15 23:38:44 gateway/gateway ipmon[121]: 23:38:43.836313 fxp0 @0:19 b 98.82.198.238,60670 -> 98.103.xxx,xxx,445 PR tcp len 20 48 -S IN broadcast Mar 15 23:38:48 gateway/gateway ipmon[121]: 23:38:48.305633 fxp0 @0:19 b 98.103.22.25 -> 98.103.xxx.xxx PR icmp len 20 92 icmp echo/0 IN broadcast Mar 15 23:38:48 gateway/gateway ipmon[121]: 23:38:48.490778 fxp0 @0:19 b 98.103.22.25 -> 98.103.xxx.xxx PR icmp len 20 92 icmp echo/0 IN Mar 15 23:38:48 gateway/gateway ipmon[121]: 23:38:48.550230 fxp0 @0:19 b 98.103.22.25 -> 98.103.xxx.xxx PR icmp len 20 92 icmp echo/0 IN broadcast Mar 15 23:43:33 gateway/gateway ipmon[121]: 23:43:33.185836 fxp0 @0:19 b 98.86.34.225,64060 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN broadcast Mar 15 23:43:34 gateway/gateway ipmon[121]: 23:43:33.405137 fxp0 @0:19 b 98.86.34.225,64081 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN Mar 15 23:43:34 gateway/gateway ipmon[121]: 23:43:33.454384 fxp0 @0:19 b 98.86.34.225,64089 -> 98.103.xxx.xxx,445 PR tcp len 20 48 -S IN broadcast I blacked out part of my IP address for my own safety.

    Read the article

  • Seeking (somewhat) better explanations about supporting > 2.1 TB hard drives.

    - by irrational John
    Today while Googling about I stumbled across posts claiming that Seagate plans to ship a 3TB drive sometime later in 2010. Unfortunately, the stuff I looked at all seemed to contain tidbits of info which I didn't think fit together properly. (I would link to some examples, but I'm only allowed 1 link per post at the moment). Now I really don't have any "need" to better understand the underlying tedious details of this. I am just curious. And confused. So ... some questions I'm hoping someone better informed than I might answer. The talk about a potential addressing problem in both the hardware and the software confused me. The assertion is that something called something called Long LBA addressing (LLBA) is needed in the Command Descriptor Block as a way to get around the current limits to access a hard drive bigger than ~2.1 (or ~2.2?) TB. OK, fine. But I thought the last time this problem came up it was solved by extending the length of the LBA field from 28 to 48 bits. (Remember this website? www.48bitlba.com) A 6 byte LBA is clearly large enough, so what's up with this LLBA talk. I thought this was all fixed back by Win XP SP2, if not sooner? And certainly all the hardware should be up to the task, shouldn't it? The real problem as I understand it with drives much bigger than 2 TB are the 4 byte LBA fields in the Master Boot Record (MBR) used to partition just about all hard drives at the moment. The most likely solution is to migrate to Intel's GUID Partition Table (GPT). A GPT uses 8 byte fields for the LBA. What I don't understand in this context is what is the problem with booting say Windows from a 3TB drive that uses a GPT. Granted, the current PC BIOS wouldn't know how to recognize or work with a GPT. But every GPT comes with a so-called "Safety" or "Guarding" MBR in sector 0.Apple already uses a hybrid version of the MBR to allow them to boot Windows on their Intel Macs (aka Boot Camp). Couldn't something similar be done to allow the PC BIOS to recognize and boot from a partition in, say, the first 1 GB of a 3GB or larger drive? I've got more questions such as where do 4K sectors fit into all of this. But it's probably time I just shut up and posted this. ;-) -irrational john

    Read the article

  • Scaling a video processing application on EC2?

    - by Stpn
    I am approaching the need to scale a video-processign application that runs on EC2. So far the setup is one machine: Backbonejs frontend Rails 3.2 Postgresql Resque + S3 for storage The flow of the app is as follows: 1) Request from frontend. Upload a video. 2) Storing video 3) Quering external APIs. 4) Processing / encoding videos. 5) Post to frontend. I can separate the backend and frontend without any problems, but when it comes to distributing the backend between several servers I am a bit puzzled. I can probably come up with a temporary solution (like just duplicating apps making several instances), but since I don't really have expertise in backend system administration, there can be some fundamental mistakes.. Also I would rather have something that is scalable. I wonder if anyone can give some feedback on the following plan: A) Frontend machine. Just frontend, talks to backend via REST Api of sorts. B) Backend server (BS), main database. Gets request from 1), posts to 2) saves uploads to 3) C) S3 storage. D) Server for quering APIs. Basically just a Resque workers, that post info back to 2) E) Server for video encoding. Processes videos uploaded on 3) and uploads them back. So I will have: A)frontend \ \ B)MAIN_APP/DB ----- C)S3 Storage (Files) / \ / / \ / D)ExternalAPI_queries E)Video_Processing (redundant DB) (redundant DB) All this will supposedly talk to each other via HTTP requests. My reason for this is that Video Processing part is really the most resource-intensive and I would just run barebones application that accepts requests and starts processing them. Questions: 1) In this setup I will have the main database at B) and all other servers will communicate with it via HTTP requests (and store duplicates of databases also I guess..for safety reasons). Is it the right approach or should I have 1 database that everyone connects to (how then?) 2) Is it a good idea to separate API queries from Video Processing part? Logically they are very close (processing is determined by the result of API queries), but resource-wise Video Processing is waaay more intensive. 3) what should I use to distribute calls between backend apps based on load?

    Read the article

  • Getting an boot error when starting computer

    - by Rob Avery IV
    I was in the middle of watching a movie on Netflix, then suddenly everything started crashing. First, explorer.exe closed down, then Google chrome. I had multiple things running in the background (Steam, Raptr, etc.). Individuality, each of those apps closed down also. When they did, a small dialog box popped up for each of them, one at a time, saying that it was missing a file, it couldn't run anymore, or something similar to that. It also had some jumbled up "code" with numbers and letters that I couldn't read. Ever since then, everytime I turn my computer on, it will run for a few seconds and give this error "Reboot and select proper boot device or insert boot media in selected boot device and press a key_". No matter how many times I try to reboot it, it always gives me the same error. A day later after this happened I was able to start the computer, but before it booted, it told me that I didn't shut down the computer properly and asked how I wanted to run the OS (Run Windows in Safety Mode, Run Windows Normally, etc.). Once I logged, everything went SUPER slow and everything crashed almost instantly. The only thing I opened was Microsoft Security Essentials and only got in about two clicks before it was "Not Responding". Then, after that the whole computer froze and I had to restart it. Now, it's back to saying what it originally said, "Reboot and select proper boot device or insert boot media in selected boot device and press a key_". I built this PC back in February 2012. Here are the specs: OS: Windows 7 Ultimate CPU: AMD 8-core GPU: Nvidia GTX Force 560 Ti RAM: 16GB Hard Drive: Hitachi Deskstar 750GB I'm usually very good taking care of my PC. I don't download anything that's not from a trusted site or source. I don't open up any spam email or such or go to any harmful websites like porn or stream movies. I am very clean with the things I do with my PC and don't do many DIFFERENT things with it. I use it pretty often especially for video games and doing homework in Eclipse. Also, good to note that I don't have any Norton or antisoftware installed. I have Microsoft Security Essentials installed but never did a scan. Thanks!

    Read the article

  • Expendable, Redundant, Easily recoverable

    - by MeIr
    I am desperate at this point, I have been looking for "Big storage" solution for a while on my own and I can't find anything that would suite my needs. But now push came to shove. Current situation: I have about 6TB data storage (already full) - Drobo. Yesterday Drobo died on me and it put me into bad situation - I can't recover my data without buying another Drobo. From extensive research online I realized that Drobo is not the safest bet and by now it seems very poor choice. I ordered new Drobo to try to get my data back, however I don't want to be in the same situation later and continuing using Drobo promises this event to re-occur. What I am looking for: 1) Inexpensive setup. 2) Dynamically extendable - add more drives and/or replace a drive with bigger capacity. 3) Redundant - setup against 1-3 drive failure, will depend on total number of drives. For the sake of argument let's assume for every 4 drives one should be able to fail without data loss. 4) Easy data recovery - let's say unforeseen happens, I would like to be able to recover information without buying new tools or replacements - example: new Drobo. 5) Should be USB or Network Attach Storage 6) No demand on speed. Doesn't have to be fast, I am not doing video editing on the setup. However if option exists, would be nice to have a decent speed. After thoughts: I reviewed few options and FreeNAS looks nice, but it doesn't have #2 - Dynamic extendability. There are work around with Pools but it seems a bit complicated and unnecessary. More over it seems like data safety is a big question - saw some horror stories. Please advise on what options I have and what seems like an optimal solution (if any). I don't care if it has to be Windows or Linux box or any other OS and/or software that has to run on top, but simple solution is more attractive. Thank you! P.S: Feel free to ignore "After thoughts".

    Read the article

  • C#: System.Lazy&lt;T&gt; and the Singleton Design Pattern

    - by James Michael Hare
    So we've all coded a Singleton at one time or another.  It's a really simple pattern and can be a slightly more elegant alternative to global variables.  Make no mistake, Singletons can be abused and are often over-used -- but occasionally you find a Singleton is the most elegant solution. For those of you not familiar with a Singleton, the basic Design Pattern is that a Singleton class is one where there is only ever one instance of the class created.  This means that constructors must be private to avoid users creating their own instances, and a static property (or method in languages without properties) is defined that returns a single static instance. 1: public class Singleton 2: { 3: // the single instance is defined in a static field 4: private static readonly Singleton _instance = new Singleton(); 5:  6: // constructor private so users can't instantiate on their own 7: private Singleton() 8: { 9: } 10:  11: // read-only property that returns the static field 12: public static Singleton Instance 13: { 14: get 15: { 16: return _instance; 17: } 18: } 19: } This is the most basic singleton, notice the key features: Static readonly field that contains the one and only instance. Constructor is private so it can only be called by the class itself. Static property that returns the single instance. Looks like it satisfies, right?  There's just one (potential) problem.  C# gives you no guarantee of when the static field _instance will be created.  This is because the C# standard simply states that classes (which are marked in the IL as BeforeFieldInit) can have their static fields initialized any time before the field is accessed.  This means that they may be initialized on first use, they may be initialized at some other time before, you can't be sure when. So what if you want to guarantee your instance is truly lazy.  That is, that it is only created on first call to Instance?  Well, there's a few ways to do this.  First we'll show the old ways, and then talk about how .Net 4.0's new System.Lazy<T> type can help make the lazy-Singleton cleaner. Obviously, we could take on the lazy construction ourselves, but being that our Singleton may be accessed by many different threads, we'd need to lock it down. 1: public class LazySingleton1 2: { 3: // lock for thread-safety laziness 4: private static readonly object _mutex = new object(); 5:  6: // static field to hold single instance 7: private static LazySingleton1 _instance = null; 8:  9: // property that does some locking and then creates on first call 10: public static LazySingleton1 Instance 11: { 12: get 13: { 14: if (_instance == null) 15: { 16: lock (_mutex) 17: { 18: if (_instance == null) 19: { 20: _instance = new LazySingleton1(); 21: } 22: } 23: } 24:  25: return _instance; 26: } 27: } 28:  29: private LazySingleton1() 30: { 31: } 32: } This is a standard double-check algorithm so that you don't lock if the instance has already been created.  However, because it's possible two threads can go through the first if at the same time the first time back in, you need to check again after the lock is acquired to avoid creating two instances. Pretty straightforward, but ugly as all heck.  Well, you could also take advantage of the C# standard's BeforeFieldInit and define your class with a static constructor.  It need not have a body, just the presence of the static constructor will remove the BeforeFieldInit attribute on the class and guarantee that no fields are initialized until the first static field, property, or method is called.   1: public class LazySingleton2 2: { 3: // because of the static constructor, this won't get created until first use 4: private static readonly LazySingleton2 _instance = new LazySingleton2(); 5:  6: // Returns the singleton instance using lazy-instantiation 7: public static LazySingleton2 Instance 8: { 9: get { return _instance; } 10: } 11:  12: // private to prevent direct instantiation 13: private LazySingleton2() 14: { 15: } 16:  17: // removes BeforeFieldInit on class so static fields not 18: // initialized before they are used 19: static LazySingleton2() 20: { 21: } 22: } Now, while this works perfectly, I hate it.  Why?  Because it's relying on a non-obvious trick of the IL to guarantee laziness.  Just looking at this code, you'd have no idea that it's doing what it's doing.  Worse yet, you may decide that the empty static constructor serves no purpose and delete it (which removes your lazy guarantee).  Worse-worse yet, they may alter the rules around BeforeFieldInit in the future which could change this. So, what do I propose instead?  .Net 4.0 adds the System.Lazy type which guarantees thread-safe lazy-construction.  Using System.Lazy<T>, we get: 1: public class LazySingleton3 2: { 3: // static holder for instance, need to use lambda to construct since constructor private 4: private static readonly Lazy<LazySingleton3> _instance 5: = new Lazy<LazySingleton3>(() => new LazySingleton3()); 6:  7: // private to prevent direct instantiation. 8: private LazySingleton3() 9: { 10: } 11:  12: // accessor for instance 13: public static LazySingleton3 Instance 14: { 15: get 16: { 17: return _instance.Value; 18: } 19: } 20: } Note, you need your lambda to call the private constructor as Lazy's default constructor can only call public constructors of the type passed in (which we can't have by definition of a Singleton).  But, because the lambda is defined inside our type, it has access to the private members so it's perfect. Note how the Lazy<T> makes it obvious what you're doing (lazy construction), instead of relying on an IL generation side-effect.  This way, it's more maintainable.  Lazy<T> has many other uses as well, obviously, but I really love how elegant and readable it makes the lazy Singleton.

    Read the article

  • Rob Blackwell on interoperability and Azure

    - by Eric Nelson
    At QCon in March we had a sample Azure application implemented in both Java and Ruby to demonstrate that the Windows Azure Platform is not just about .NET. The following is an interesting interview with Rob Blackwell, the R&D director of the partner who implemented the application. UK Interoperability Team Interviews Rob Blackwell, R&D Director at Active Web Solutions. Is Microsoft taking interoperability seriously? Yes. In the past, I think Microsoft has, quite rightly come in for criticism, but architects and developers should look at this again. The Interoperability Bridges site (http://www.interoperabilitybridges.com/ ) shows a wide range of projects that allow interoperability from Java, Ruby and PHP for example. The Windows Azure platform has been architected with interoperable APIs in mind. It's straightforward to access the various storage facilities from just about any language or platform. Azure compute is capable of running more than just C# applications! Why is interoperability important to you? My company provides consultancy and bespoke development services. We're a Microsoft Gold Partner, but we live in the real world where companies have a mix of technologies provided by a variety of vendors. When developing an enterprise software solution, you rarely have a completely blank canvas. We often see integration scenarios where we need to exchange data with legacy systems. It's not unusual to see modern Silverlight applications being built on top of Java or Mainframe based back ends. Could you give us some examples of where interoperability has been important for your projects? We developed an innovative Sea Safety system for the RNLI Lifeboats here in the UK. Commercial Fishing is one of the most dangerous professions and we helped developed the MOB Guardian System which uses satellite technology and man overboard devices to raise the alarm when a fisherman gets into trouble. The solution is implemented in .NET running on Windows, but without interoperable standards, it would have been impossible to communicate with the satellite gateway technology. For more information, please see the case study: http://www.microsoft.com/casestudies/Case_Study_Detail.aspx?CaseStudyID=4000005892 More recently, we were asked to build a web site to accompany the QCon 2010 conference in London to help demonstrate and promote interoperability. We built the site using Java and Restlet and hosted it in Windows Azure Compute. The site accepts feedback from visitors and all the data is stored in Windows Azure Storage. We also ported the application to Ruby on Rails for demonstration purposes. Visitors to the stand were surprised that this was even possible. Why should Java developers be interested in Windows Azure? Windows Azure Storage consists of Blobs, Queues and Tables. The storage is scalable, durable, secure and cost-effective. Using the WindowsAzure4j library, it's easy to use, and takes just a few lines of code. If you are writing an application with large data storage requirements, or you want an offsite backup, it makes a lot of sense. Running Java applications in Azure Compute is straightforward with tools like the Tomcat Solution Accelerator (http://code.msdn.microsoft.com/winazuretomcat )and AzureRunMe (http://azurerunme.codeplex.com/ ). The Windows Azure AppFabric Service Bus can also be used to connect heterogeneous systems running on different networks and in different data centres. How can The Service Bus be considered an interoperability solution? I think that the Windows Azure AppFabric Service Bus is one of Microsoft’s best kept secrets. Think of it as “a globally scalable application plumbing kit in the sky”. If you have used Enterprise Service Buses before, you’ll be familiar with the concept. Applications can connect to the service bus to securely exchange data – these can be point to point or multicast links. With the AppFabric Service Bus, the applications can exist anywhere that has access to the Internet and the connections can traverse firewalls. This makes it easy to extend or scale your application or reach out to other networks and technologies. For example, let’s say you have a SQL Server database running on premises and you want to expose the data to a Java application running in the cloud. You could set up a point to point Service Bus connection and use JDBC. Traditionally this would have been difficult or impossible without punching holes in firewalls and compromising security. Rob Blackwell is R&D Director at Active Web Solutions, www.aws.net , a Microsoft Gold Partner specialising in leading edge software solutions. He is an occasional writer and conference speaker and blogs at www.robblackwell.org.uk Related Links: UK Azure Online Community – join today. UK Windows Azure Site Start working with Windows Azure

    Read the article

< Previous Page | 19 20 21 22 23 24 25 26 27  | Next Page >