Search Results

Search found 5410 results on 217 pages for 'n tier architecture'.

Page 59/217 | < Previous Page | 55 56 57 58 59 60 61 62 63 64 65 66  | Next Page >

  • IPC between multiple processes on multiple servers

    - by z8000
    Let's say you have 2 servers each with 8 CPU cores each. The servers each run 8 network services that each host an arbitrary number of long-lived TCP/IP client connections. Clients send messages to the services. The services do something based on the messages, and potentially notify N1 of the clients of state changes. Sure, it sounds like a botnet but it isn't. Consider how IRC works with c2s and s2s connections and s2s message relaying. The servers are in the same data center. The servers can communicate over a private VLAN @1GigE. Messages are < 1KB in size. How would you coordinate which services on which host should receive and relay messages to connected clients for state change messages? There's an infinite number of ways to solve this problem efficiently. AMQP (RabbitMQ, ZeroMQ, etc.) Spread Toolkit N^2 connections between allservices (bad) Heck, even run IRC! ... I'm looking for a solution that: perhaps exploits the fact that there's only a small closed cluster is easy to admin scales well is "dumb" (no weird edge cases) What are your experiences? What do you recommend? Thanks!

    Read the article

  • Estimate of Hits / Visits / Uniques in order to fall within a given Alexa Tier?

    - by Alex C
    Hi there! I was wondering if anyone could offer up rough estimates that could tell me how many hits a day move you into a given Alexa rank ? Top 5,000 Top 10,000 Top 50,000 Top 100,000 Top 500,000 Top 1,000,000 I know this is incredibly subjective and thus the broad brush strokes with the number ranges... BUT I've got a site currently ranked just over 1.2M worldwide and over 500k in the USA (http://www.alexa.com/siteinfo/fstr.net) Pretty cool for something hand-built on weekends (pat self on back) I was applying to an ad-platform and was told that their program doesn't accept webmasters who have an Alexa rank of greater than 100,000. (Time to take back that pat on the back I guess). I know that my hits in the last 30 days are somewhere on the order of 15,000 uniques and 20,000 pageviews. So I'm wondering how much harder do I have to work to achieve my next "goals"? I'd like to break into the top million, then re-evaluate from there. It'd be nice to know what those targets translate into (very roughly of course). I imagine that alexa ranks and tiers become very much exponential as you move up the ranks, but even hearing annecdotal evidence from other webmasters would be really useful to me. (ie: I have a site that is ranked X and it got Y hits in the last 30 days) Thanks :) - Alex

    Read the article

  • Difference between “system-on-chip” and “CPU”

    - by Tim
    Very confused, in some websites, they have this line: iPhone 5s CPU: Apple A7 other websites saying that: iPhone 5s System-on-chip: Apple 7 CPU: 1.3 GHz 64bit dual core other sources saying that iPhone 5s System-on-chip: Apple 7 CPU: 1.3 GHz 64bit dual core Apple 7 In Wikipedia, it said: The Apple A7 is a 64-bit system on a chip (SoC) designed by Apple Inc. It first appeared in the iPhone 5S, which was introduced on September 10, 2013. Apple states that it is up to twice as fast and has up to twice the graphics power compared to its predecessor, the Apple A6. While not the first 64-bit ARM CPU, it is the first to ship in a consumer smartphone or tablet computer. There are 2 sentences: The Apple A7 is a 64-bit system on a chip (SoC) and While not the first 64-bit ARM CPU Wikipedia also said “The A7 features an Apple-designed 64-bit 1.3–1.4 GHz ARMv8-A dual-core CPU, called Cyclone”. So System on chip is also CPU? very confused

    Read the article

  • Servers - Buying New vs Buying Second-hand

    - by Django Reinhardt
    We're currently in the process of adding additional servers to our website. We have a pretty simple topology planned: A Firewall/Router Server infront of a Web Application Server and Database Server. Here's a simple (and technically incorrect) diagram that I used in a previous question to illustrate what I mean: We're now wondering about the specs of our two new machines (the Web App and Firewall servers) and whether we can get away with buying a couple of old servers. (Note: Both machines will be running Windows Server 2008 R2.) We're not too concerned about our Firewall/Router server as we're pretty sure it won't be taxed too heavily, but we are interested in our Web App server. I realise that answering this type of question is really difficult without a ton of specifics on users, bandwidth, concurrent sessions, etc, etc., so I just want to focus on the general wisdom on buying old versus new. I had originally specced a new Dell PowerEdge R300 (1U Rack) for our company. In short, because we're going to be caching as much data as possible, I focussed on Processor Speed and Memory: Quad-Core Intel Xeon X3323 2.5Ghz (2x3M Cache) 1333Mhz FSB 16GB DDR2 667Mhz But when I was looking for a cheap second-hand machine for our Firewall/Router, I came across several machines that made our engineer ask a very reasonable question: If we stuck a boat load of RAM in this thing, wouldn't it do for the Web App Server and save us a ton of money in the process? For example, what about a second-hand machine with the following specs: 2x Dual-Core AMD Opteron 2218 2.6Ghz (2MB Cache) 1000Mhz HT 16GB DDR2 667Mhz Would it really be comparable with the more expensive (new) server above? Our engineer postulated that the reason companies upgrade their servers to newer processors is often because they want to reduce their power costs, and that a 2.6Ghz processor was still a 2.6Ghz processor, no matter when it was made. Benchmarks on various sites don't really support this theory, but I was wondering what server admin thought. Thanks for any advice.

    Read the article

  • Architectural advice - web camera remote access

    - by Alan Hollis
    I'm looking for architectural advice. I have a client who I've built a website for which essentially allows users to view their web cameras remotely. The current flow of data is as follows: User opens page to view web camera image. Javascript script polls url on server ( appended with unique timestamp ) every 1000ms Ftp connection is enabled for the cameras ftp user. Web camera opens ftp connection to server. Web camera begins taking photos. Web camera sends photo to ftp server. On image url request: Server reads latest image on hard drive uploaded via ftp for camera. Server deleted any older images from the server. This is working okay at the moment for a small amount of users/cameras ( about 10 users and around the same amount of cameras), but we're starting to worrying about the scalability of this approach. My original plan was instead of having the files read from the server, the web server would open up an ftp connection to the web server and read the latest images directly from there meaning we should have been able to scale horizontally fairly easily. But ftp connection establishment times were too slow ( mainly due to the fact that PHP out of the ox is unable to persist ftp connections ) and so we abandoned this approach and went straight for reading from the hard drive. The firmware provider for the cameras state they're able to build a http client which instead of using ftp to upload the image could post the image to a web server. This seems plausible enough to me, but I'm looking for some architectural advice. My current thought is a simple Nginx/PHP/Redis stack. Web camera issues post requests of latest image to Nginx/PHP and the latest image for that camera is stored in Redis. The clients can then pull the latest image from Redis which should be extremely quick as the images will always be stored in memory. The data flow would then become: User opens page to view web camera image. Javascript script polls url on server ( appended with unique timestamp ) every 1000ms Camera is sent an http request to start posting images to a provided url Web camera begins taking photos. Web camera sends post requests to server as fast as it can On image url request: Server reads latest image from redis Server tells redis to delete later image My questions are: Are there any greater overheads of transferring images via HTTP instead of FTP? Is there a simple way to calculate how many potential cameras we could have streaming at once? Is there any way to prevent potentially DOS'ing our own servers due to web camera requests? Is Redis a good solution to this problem? Should I abandon PHP/Ngix combination and go for something else? Is this proposed solution actually any good? Will adding HTTPs to the mix cause posting the image to become too slow? Thanks in advance Alan

    Read the article

  • Install correct libraries depending on 64/32 bit

    - by Rich
    I am using Bash to install a customised version of JBoss, and one of the things I would like to do is install the correct version of the Apache Portable Runtime, which is a native binary. This script could be run on both 32 and 64 bit versions of RHEL. What are my options for identifying which version of the APR to install? I think we only have 32bit and x64-based systems here. I would still like to identify i64 systems so that the script can refuse to install on that type of machine. I am aware of using uname -m and grepping /proc/cpuinfo to find out, but was wondering which approach others would recommend?

    Read the article

  • equivalent to CDN but for dynamical content?

    - by ajsie
    so i know for serving static elements (css, js, images, videos etc) you should use CDN since they are spread out throughout the world. but how could i spread out by apache servers? is there an equivalent to CDN but for dynamical pages? or is it the traditional LAMP way. if so, i guess my best option is to find an international hosting provider that hosts in different countries, so the content will be served from the country located nearest the client machine. any suggestions of such hosting providers? or is it best practice to contact different hosting providers in different countries that do not relate to each other. what is the right way to go?

    Read the article

  • NDepend: How to not display 'tier' assemblies in dependency graph?

    - by Edward Buatois
    I was able to do this in an earlier version of nDepend by going to tools-options and setting which assemblies would be part of the analysis (and ignore the rest). The latest version of the trial version of nDepend lets me set it, but it seems to ignore the setting and always analyze all assemblies whether I want it to or not. I tried to delete the "tier" assemblies by moving them over to the "application assemblies" list, but when I delete them out of there, they just get added back to the "tier" list, which I can't ignore. I don't want my dependency graph to contain assemblies like "system," "system.xml," and "system.serialization!" I want only MY assemblies in the dependency graph! Or is that a paid-version feature now? Is there a way to do what I'm talking about?

    Read the article

  • NDepend: How to not display 'tier' assemblies in dependency graph?

    - by Edward Buatois
    I was able to do this in an earlier version of nDepend by going to tools-options and setting which assemblies would be part of the analysis (and ignore the rest). The latest version of the trial version of nDepend lets me set it, but it seems to ignore the setting and always analyze all assemblies whether I want it to or not. I tried to delete the "tier" assemblies by moving them over to the "application assemblies" list, but when I delete them out of there, they just get added back to the "tier" list, which I can't ignore. I don't want my dependency graph to contain assemblies like "system," "system.xml," and "system.serialization!" I want only MY assemblies in the dependency graph! Or is that a paid-version feature now? Is there a way to do what I'm talking about?

    Read the article

  • Windows Azure: General Availability of Web Sites + Mobile Services, New AutoScale + Alerts Support, No Credit Card Needed for MSDN

    - by ScottGu
    This morning we released a major set of updates to Windows Azure.  These updates included: Web Sites: General Availability Release of Windows Azure Web Sites with SLA Mobile Services: General Availability Release of Windows Azure Mobile Services with SLA Auto-Scale: New automatic scaling support for Web Sites, Cloud Services and Virtual Machines Alerts/Notifications: New email alerting support for all Compute Services (Web Sites, Mobile Services, Cloud Services, and Virtual Machines) MSDN: No more credit card requirement for sign-up All of these improvements are now available to use immediately (note: some are still in preview).  Below are more details about them. Web Sites: General Availability Release of Windows Azure Web Sites I’m incredibly excited to announce the General Availability release of Windows Azure Web Sites. The Windows Azure Web Sites service is perfect for hosting a web presence, building customer engagement solutions, and delivering business web apps.  Today’s General Availability release means we are taking off the “preview” tag from the Free and Standard (formerly called reserved) tiers of Windows Azure Web Sites.  This means we are providing: A 99.9% monthly SLA (Service Level Agreement) for the Standard tier Microsoft Support available on a 24x7 basis (with plans that range from developer plans to enterprise Premier support) The Free tier runs in a shared compute environment and supports up to 10 web sites. While the Free tier does not come with an SLA, it works great for rapid development and testing and enables you to quickly spike out ideas at no cost. The Standard tier, which was called “Reserved” during the preview, runs using dedicated per-customer VM instances for great performance, isolation and scalability, and enables you to host up to 500 different Web sites within them.  You can easily scale your Standard instances on-demand using the Windows Azure Management Portal.  You can adjust VM instance sizes from a Small instance size (1 core, 1.75GB of RAM), up to a Medium instance size (2 core, 3.5GB of RAM), or Large instance (4 cores and 7 GB RAM).  You can choose to run between 1 and 10 Standard instances, enabling you to easily scale up your web backend to 40 cores of CPU and 70GB of RAM: Today’s release also includes general availability support for custom domain SSL certificate bindings for web sites running using the Standard tier. Customers will be able to utilize certificates they purchase for their custom domains and use either SNI or IP based SSL encryption. SNI encryption is available for all modern browsers and does not require an IP address.  SSL certificates can be used for individual sites or wild-card mapped across multiple sites (we charge extra for the use of a SSL cert – but the fee is per-cert and not per site which means you pay once for it regardless of how many sites you use it with).  Today’s release also includes the following new features: Auto-Scale support Today’s Windows Azure release adds preview support for Auto-Scaling web sites.  This enables you to setup automatic scale rules based on the activity of your instances – allowing you to automatically scale down (and save money) when they are below a CPU threshold you define, and automatically scale up quickly when traffic increases.  See below for more details. 64-bit and 32-bit mode support You can now choose to run your standard tier instances in either 32-bit or 64-bit mode (previously they only ran in 32-bit mode).  This enables you to address even more memory within individual web applications. Memory dumps Memory dumps can be very useful for diagnosing issues and debugging apps. Using a REST API, you can now get a memory dump of your sites, which you can then use for investigating issues in Visual Studio Debugger, WinDbg, and other tools. Scaling Sites Independently Prior to today’s release, all sites scaled up/down together whenever you scaled any site in a sub-region. So you may have had to keep your proof-of-concept or testing sites in a separate sub-region if you wanted to keep them in the Free tier. This will no longer be necessary.  Windows Azure Web Sites can now mix different tier levels in the same geographic sub-region. This allows you, for example, to selectively move some of your sites in the West US sub-region up to Standard tier when they require the features, scalability, and SLA of the Standard tier. Full pricing details on Windows Azure Web Sites can be found here.  Note that the “Shared Tier” of Windows Azure Web Sites remains in preview mode (and continues to have discounted preview pricing).  Mobile Services: General Availability Release of Windows Azure Mobile Services I’m incredibly excited to announce the General Availability release of Windows Azure Mobile Services.  Mobile Services is perfect for building scalable cloud back-ends for Windows 8.x, Windows Phone, Apple iOS, Android, and HTML/JavaScript applications.  Customers We’ve seen tremendous adoption of Windows Azure Mobile Services since we first previewed it last September, and more than 20,000 customers are now running mobile back-ends in production using it.  These customers range from startups like Yatterbox, to university students using Mobile Services to complete apps like Sly Fox in their spare time, to media giants like Verdens Gang finding new ways to deliver content, and telcos like TalkTalk Business delivering the up-to-the-minute information their customers require.  In today’s Build keynote, we demonstrated how TalkTalk Business is using Windows Azure Mobile Services to deliver service, outage and billing information to its customers, wherever they might be. Partners When we unveiled the source control and Custom API features I blogged about two weeks ago, we enabled a range of new scenarios, one of which is a more flexible way to work with third party services.  The following blogs, samples and tutorials from our partners cover great ways you can extend Mobile Services to help you build rich modern apps: New Relic allows developers to monitor and manage the end-to-end performance of iOS and Android applications connected to Mobile Services. SendGrid eliminates the complexity of sending email from Mobile Services, saving time and money, while providing reliable delivery to the inbox. Twilio provides a telephony infrastructure web service in the cloud that you can use with Mobile Services to integrate phone calls, text messages and IP voice communications into your mobile apps. Xamarin provides a Mobile Services add on to make it easy building cross-platform connected mobile aps. Pusher allows quickly and securely add scalable real-time messaging functionality to Mobile Services-based web and mobile apps. Visual Studio 2013 and Windows 8.1 This week during //build/ keynote, we demonstrated how Visual Studio 2013, Mobile Services and Windows 8.1 make building connected apps easier than ever. Developers building Windows 8 applications in Visual Studio can now connect them to Windows Azure Mobile Services by simply right clicking then choosing Add Connected Service. You can either create a new Mobile Service or choose existing Mobile Service in the Add Connected Service dialog. Once completed, Visual Studio adds a reference to Mobile Services SDK to your project and generates a Mobile Services client initialization snippet automatically. Add Push Notifications Push Notifications and Live Tiles are a key to building engaging experiences. Visual Studio 2013 and Mobile Services make it super easy to add push notifications to your Windows 8.1 app, by clicking Add a Push Notification item: The Add Push Notification wizard will then guide you through the registration with the Windows Store as well as connecting your app to a new or existing mobile service. Upon completion of the wizard, Visual Studio will configure your mobile service with the WNS credentials, as well as add sample logic to your client project and your mobile service that demonstrates how to send push notifications to your app. Server Explorer Integration In Visual Studio 2013 you can also now view your Mobile Services in the the Server Explorer. You can add tables, edit, and save server side scripts without ever leaving Visual Studio, as shown on the image below: Pricing With today’s general availability release we are announcing that we will be offering Mobile Services in three tiers – Free, Standard, and Premium.  Each tier is metered using a simple pricing model based on the # of API calls (bandwidth is included at no extra charge), and the Standard and Premium tiers are backed by 99.9% monthly SLAs.  You can elastically scale up or down the number of instances you have of each tier to increase the # of API requests your service can support – allowing you to efficiently scale as your business grows. The following table summarizes the new pricing model (full pricing details here):   You can find the full details of the new pricing model here. Build Conference Talks The //BUILD/ conference will be packed with sessions covering every aspect of developing connected applications with Mobile Services. The best part is that, even if you can’t be with us in San Francisco, every session is being streamed live. Be sure not to miss these talks: Mobile Services – Soup to Nuts — Josh Twist Building Cross-Platform Apps with Windows Azure Mobile Services — Chris Risner Connected Windows Phone Apps made Easy with Mobile Services — Yavor Georgiev Build Connected Windows 8.1 Apps with Mobile Services — Nick Harris Who’s that user? Identity in Mobile Apps — Dinesh Kulkarni Building REST Services with JavaScript — Nathan Totten Going Live and Beyond with Windows Azure Mobile Services — Kirill Gavrylyuk , Paul Batum Protips for Windows Azure Mobile Services — Chris Risner AutoScale: Dynamically scale up/down your app based on real-world usage One of the key benefits of Windows Azure is that you can dynamically scale your application in response to changing demand. In the past, though, you have had to either manually change the scale of your application, or use additional tooling (such as WASABi or MetricsHub) to automatically scale your application. Today, we’re announcing that AutoScale will be built-into Windows Azure directly.  With today’s release it is now enabled for Cloud Services, Virtual Machines and Web Sites (Mobile Services support will come soon). Auto-scale enables you to configure Windows Azure to automatically scale your application dynamically on your behalf (without any manual intervention) so you can achieve the ideal performance and cost balance. Once configured it will regularly adjust the number of instances running in response to the load in your application. Currently, we support two different load metrics: CPU percentage Storage queue depth (Cloud Services and Virtual Machines only) We’ll enable automatic scaling on even more scale metrics in future updates. When to use Auto-Scale The following are good criteria for services/apps that will benefit from the use of auto-scale: The service/app can scale horizontally (e.g. it can be duplicated to multiple instances) The service/app load changes over time If your app meets these criteria, then you should look to leverage auto-scale. How to Enable Auto-Scale To enable auto-scale, simply navigate to the Scale tab in the Windows Azure Management Portal for the app/service you wish to enable.  Within the scale tab turn the Auto-Scale setting on to either CPU or Queue (for Cloud Services and VMs) to enable Auto-Scale.  Then change the instance count and target CPU settings to configure the Auto-Scale ranges you want to maintain. The image below demonstrates how to enable Auto-Scale on a Windows Azure Web-Site.  I’ve configured the web-site so that it will run using between 1 and 5 VM instances.  The exact # used will depend on the aggregate CPU of the VMs using the 40-70% range I’ve configured below.  If the aggregate CPU goes above 70%, then Windows Azure will automatically add new VMs to the pool (up to the maximum of 5 instances I’ve configured it to use).  If the aggregate CPU drops below 40% then Windows Azure will automatically start shutting down VMs to save me money: Once you’ve turned auto-scale on, you can return to the Scale tab at any point and select Off to manually set the number of instances. Using the Auto-Scale Preview With today’s update you can now, in just a few minutes, have Windows Azure automatically adjust the number of instances you have running  in your apps to keep your service performant at an even better cost. Auto-scale is being released today as a preview feature, and will be free until General Availability. During preview, each subscription is limited to 10 separate auto-scale rules across all of the resources they have (Web sites, Cloud services or Virtual Machines). If you hit the 10 limit, you can disable auto-scale for any resource to enable it for another. Alerts and Notifications Starting today we are now providing the ability to configure threshold based alerts on monitoring metrics. This feature is available for compute services (cloud services, VM, websites and mobiles services). Alerts provide you the ability to get proactively notified of active or impending issues within your application.  You can define alert rules for: Virtual machine monitoring metrics that are collected from the host operating system (CPU percentage, network in/out, disk read bytes/sec and disk write bytes/sec) and on monitoring metrics from monitoring web endpoint urls (response time and uptime) that you have configured. Cloud service monitoring metrics that are collected from the host operating system (same as VM), monitoring metrics from the guest VM (from performance counters within the VM) and on monitoring metrics from monitoring web endpoint urls (response time and uptime) that you have configured. For Web Sites and Mobile Services, alerting rules can be configured on monitoring metrics from monitoring endpoint urls (response time and uptime) that you have configured. Creating Alert Rules You can add an alert rule for a monitoring metric by navigating to the Setting -> Alerts tab in the Windows Azure Management Portal. Click on the Add Rule button to create an alert rule. Give the alert rule a name and optionally add a description. Then pick the service which you want to define the alert rule on: The next step in the alert creation wizard will then filter the monitoring metrics based on the service you selected:   Once created the rule will show up in your alerts list within the settings tab: The rule above is defined as “not activated” since it hasn’t tripped over the CPU threshold we set.  If the CPU on the above machine goes over the limit, though, I’ll get an email notifying me from an Windows Azure Alerts email address ([email protected]). And when I log into the portal and revisit the alerts tab I’ll see it highlighted in red.  Clicking it will then enable me to see what is causing it to fail, as well as view the history of when it has happened in the past. Alert Notifications With today’s initial preview you can now easily create alerting rules based on monitoring metrics and get notified on active or impending issues within your application that require attention. During preview, each subscription is limited to 10 alert rules across all of the services that support alert rules. No More Credit Card Requirement for MSDN Subscribers Earlier this month (during TechEd 2013), Windows Azure announced that MSDN users will get Windows Azure Credits every month that they can use for any Windows Azure services they want. You can read details about this in my previous Dev/Test blog post. Today we are making further updates to enable an easier Windows Azure signup for MSDN users. MSDN users will now not be required to provide payment information (e.g. no credit card) during sign-up, so long as they use the service within the included monetary credit for the billing period. For usage beyond the monetary credit, they can enable overages by providing the payment information and remove the spending limit. This enables a super easy, one page sign-up experience for MSDN users.  Simply sign-up for your Windows Azure trial using the same Microsoft ID that you use to manage your MSDN account, then complete the one page sign-up form below and you will be able to spend your free monthly MSDN credits (up to $150 each month) on any Windows Azure resource for dev/test:   This makes it trivially easy for every MDSN customer to start using Windows Azure today.  If you haven’t signed up yet, I definitely recommend checking it out. Summary Today’s release includes a ton of great features that enable you to build even better cloud solutions.  If you don’t already have a Windows Azure account, you can sign-up for a free trial and start using all of the above features today.  Then visit the Windows Azure Developer Center to learn more about how to build apps with it. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

    Read the article

  • Organization &amp; Architecture UNISA Studies &ndash; Chap 5

    - by MarkPearl
    Learning Outcomes Describe the operation of a memory cell Explain the difference between DRAM and SRAM Discuss the different types of ROM Explain the concepts of a hard failure and a soft error respectively Describe SDRAM organization Semiconductor Main Memory The two traditional forms of RAM used in computers are DRAM and SRAM DRAM (Dynamic RAM) Divided into two technologies… Dynamic Static Dynamic RAM is made with cells that store data as charge on capacitors. The presence or absence of charge in a capacitor is interpreted as a binary 1 or 0. Because capacitors have natural tendency to discharge, dynamic RAM requires periodic charge refreshing to maintain data storage. The term dynamic refers to the tendency of the stored charge to leak away, even with power continuously applied. Although the DRAM cell is used to store a single bit (0 or 1), it is essentially an analogue device. The capacitor can store any charge value within a range, a threshold value determines whether the charge is interpreted as a 1 or 0. SRAM (Static RAM) SRAM is a digital device that uses the same logic elements used in the processor. In SRAM, binary values are stored using traditional flip flop logic configurations. SRAM will hold its data as along as power is supplied to it. Unlike DRAM, no refresh is required to retain data. SRAM vs. DRAM DRAM is simpler and smaller than SRAM. Thus it is more dense and less expensive than SRAM. The cost of the refreshing circuitry for DRAM needs to be considered, but if the machine requires a large amount of memory, DRAM turns out to be cheaper than SRAM. SRAMS are somewhat faster than DRAM, thus SRAM is generally used for cache memory and DRAM is used for main memory. Types of ROM Read Only Memory (ROM) contains a permanent pattern of data that cannot be changed. ROM is non volatile meaning no power source is required to maintain the bit values in memory. While it is possible to read a ROM, it is not possible to write new data into it. An important application of ROM is microprogramming, other applications include library subroutines for frequently wanted functions, System programs, Function tables. A ROM is created like any other integrated circuit chip, with the data actually wired into the chip as part of the fabrication process. To reduce costs of fabrication, we have PROMS. PROMS are… Written only once Non-volatile Written after fabrication Another variation of ROM is the read-mostly memory, which is useful for applications in which read operations are far more frequent than write operations, but for which non volatile storage is required. There are three common forms of read-mostly memory, namely… EPROM EEPROM Flash memory Error Correction Semiconductor memory is subject to errors, which can be classed into two categories… Hard failure – Permanent physical defect so that the memory cell or cells cannot reliably store data Soft failure – Random error that alters the contents of one or more memory cells without damaging the memory (common cause includes power supply issues, etc.) Most modern main memory systems include logic for both detecting and correcting errors. Error detection works as follows… When data is to be read into memory, a calculation is performed on the data to produce a code Both the code and the data are stored When the previously stored word is read out, the code is used to detect and possibly correct errors The error checking provides one of 3 possible results… No errors are detected – the fetched data bits are sent out An error is detected, and it is possible to correct the error. The data bits plus error correction bits are fed into a corrector, which produces a corrected set of bits to be sent out An error is detected, but it is not possible to correct it. This condition is reported Hamming Code See wiki for detailed explanation. We will probably need to know how to do a hemming code – refer to the textbook (pg. 188 – 189) Advanced DRAM organization One of the most critical system bottlenecks when using high-performance processors is the interface to main memory. This interface is the most important pathway in the entire computer system. The basic building block of main memory remains the DRAM chip. In recent years a number of enhancements to the basic DRAM architecture have been explored, and some of these are now on the market including… SDRAM (Synchronous DRAM) DDR-DRAM RDRAM SDRAM (Synchronous DRAM) SDRAM exchanges data with the processor synchronized to an external clock signal and running at the full speed of the processor/memory bus without imposing wait states. SDRAM employs a burst mode to eliminate the address setup time and row and column line precharge time after the first access In burst mode a series of data bits can be clocked out rapidly after the first bit has been accessed SDRAM has a multiple bank internal architecture that improves opportunities for on chip parallelism SDRAM performs best when it is transferring large blocks of data serially There is now an enhanced version of SDRAM known as double data rate SDRAM or DDR-SDRAM that overcomes the once-per-cycle limitation of SDRAM

    Read the article

  • Can a partition table be edited from a LiveUSB of another architecture?

    - by Eliran Malka
    My purpose is to re-partition a dual-boot machine (running Ubuntu 13.04 / Windows 7), i.e. the current table is as follows: ----------------------------------------------------------- | | extended partition | | | windows |--------------------------------| recovery | | (NTFS) | swap | filesystem | (NTFS) | | | (swap) | (ext4) | | ----------------------------------------------------------- and I want to create an additional ext4 partition under the extended partition, and mount those (the one I created and the 'filesystem' partition) to root and home (/ and /home), such as the new layout will be: ----------------------------------------------------------- | | extended partition | | | windows |--------------------------------| recovery | | (NTFS) | swap | root | home | (NTFS) | | | (swap) | (ext4) | (ext4) | | ----------------------------------------------------------- As the installations on the system and on my Live USB differ in architecture, I want to know: Is it safe to use a 64bit GParted from a Live USB for partitioning a 32bit installation?

    Read the article

  • ASP.NET MVC Portable Areas - Can they communicate and be used as a plugin-like architecture?

    - by Beton
    I'll get straight to the point: I was wondering if there is a common pattern to use portable areas as a components of a plugin-like architecture. Example: We've got 3 plugins (portable areas) packaged and distributed via NuGet feed. Each of them is following the standard MVC structure (has it own Models, Views and Controllers). Lets say login form, header and footer. What I was wondering if there is a way to make them communicate. For example: when user logs on, login plugin executes it own logic, logs the user and then it updates the state of the header plugin with changes it state accordingly. Thanks in advance.

    Read the article

  • WCF Data Services implementation strategies.

    - by Nix
    Microsoft has done a savvy job of not outlining the actual place for data services in the wonderful world of SOA/Web dev. So my question is simple, are WCF Data Services designed to be used via clients? Or has anyone ever heard of someone using them on the server side? Simple scenario a general layered architecture using BO business objects (parenthesis indicate what is being passed between layers) (XML) WCF Service - (BO)Business Logic - (BO) Dao - Entity Framework or using data services it would be where DS BO are modeled business entities to be used in data service. (XML) WCF Service -(BO) Business Logic - (BO) WCF Data Service - (DS BO)Server I can't see a use for the later, unless there are going to be a lot of cases people would be accessing your data via your Data Service Layer vs the Service layer? Thoughts anyone? I have not seen any mention of using DS from within a Service Layer....

    Read the article

  • java enterprise project

    - by darko petreski
    Hi All, All the time we are hearing that java is enterprise. We have read many books about jpa, entity beans and other stuff. All this books explain this technology with some dummy examples. I have not seen a book that explains real problems with enterprise beans, java clients and security! I mean real book not some imaginated stupid examples . Is there any book that describes completely some enterprise system, Its architecture, communication, security, of course the client that uses the distributed components ? I need a book that will cover the flowing: server side components (ejb, jpa) client side java desktop application security (authentication and authorization) web services with complete authentication clustering (we can find for all of this a book, but there is no book that covers all this things in one piece. Also all the books are with dummy samples.) Or may be some project that is documented. Regards, Darko

    Read the article

  • Expose url to webservice

    - by Patrick Peters
    In our project we want to query a document management system for a specific document or movie. The dms returns a URL with the document location (for example: http://mydomain.myserver1.share/mypdf.pdf or http://mydomain.myserver2.share/mymovie.avi). We want to expose the document to internet users and intranet users. The requested file can be large (large video files). Our architecture is like: request goes like: webapp1 - webapp2 - webapp3 - dms response goes like: dms - webapp3 - webapp2 - webapp1 webapp1 could be on the internet. I have have been thinking how we can obfusicate the real url from the dms, due to security issues. I have seen implementations from other webapps where the pdf URL was obfusicated by creating a temp file for the requested document that is specific for the session and user. So other users cannot easily guess the documentname of other users. My question: is there a pattern that deals with exposing company/user vulernable data to the public ? Our development is in C# 3.5.

    Read the article

  • JBoss Seam - Jetty - Virtualhosting

    - by Walter White
    Hi all, I am trying to cutback on the memory usage of my server and would like to optimize the architecture. I currently deploy 2 separate web applications to Jetty 6.1.22 that correspond to different virtualhosts. They have pretty much the same application stack except one has fewer components and are styled differently (content, images, css, etc.). If I change my design pattern over to EJB / EAR + 2 WARS embedded, will that lower the memory consumption? Will that give me a single instance of JBoss Seam, Quartz, and all of my components? They must use a different datasource. Thanks, Walter

    Read the article

  • Circular Dependency Solution

    - by gfoley
    Our current project has ran into a circular dependency issue. Our business logic assembly is using classes and static methods from our SharedLibrary assembly. The SharedLibrary contains a whole bunch of helper functions, such as a SQL Reader class, Enumerators, Global Variables, Error Handling, Logging and Validation. The SharedLibrary needs access to the Business objects, but the Business objects need access to SharedLibrary. The old developers solved this obvious code smell by replicating the functionality of the business objects in the shared library (very anti-DRY). I've spent a day now trying to read about my options to solve this but i'm hitting a dead end. I'm open to the idea of architecture redesign, but only as a last resort. So how can i have a Shared Helper Library which can access the business objects, with the business objects still accessing the Shared Helper Library?

    Read the article

  • .Net opening and closing database connections

    - by Dan
    I designed the data access portion of our framework so that every time a business object needs to interact with the database it would have to open a connection, invoke the data access layer (to execute the query), and then close the connection. Then if it needed to run in a transaction it would open the connection, begin the transaction, invoke the data access layer (to execute the query) and then commit the transaction, close the transaction, and finally close the connection. I did it this way with the mindset of open late and close early... but what if I needed to call other BO's to submit data in a single transaction? Is there a better way to handle opening and closing connections as well as working with transactions? I'm a rookie in designing application architecture so I hope I'm not doing this wrongly... any help is appreciated.

    Read the article

  • REST doesn't work with Sever-Client-Client setup

    - by drozzy
    I am having a problem with my current RESTful api design. What I have is a REST api which is consumed by Django web-server, which renders the HTML templates. REST api > Django webserver > HTML The problem I am encountering is that I have to reconstruct all the URLS like mysite.com/main/cities/<id>/streets/ into equivalent rest api urls on my web-server layer: api.com/cities/<id>/streets/ Thus I have a lot of mapping back and forth, but as far as I know REST says that the client (in this case my web-server) should NOT need to know how to re-construct the urls. Can REST be used for such a setup and how? Or is it only viable for Server-Client architecture. Thanks

    Read the article

  • How to determine OS Platform with WMI?

    - by cary.wagner
    I am trying to figure out if there is a location in WMI that will return the OS Architecture (i.e. 32-bit or 64-bit) that will work across "all" versions of Windows. I thought I had figured it out looking at my Win2k8 system when I found the following: Win32_OperatingSystem / OSArchitecture I was wrong. It doesn't appear that this field exists on Win2k3 systems. Argh! So, is anyone aware of another field in WMI that "is" the same across server versions? If not, what about a registry key that is the same? I am using a tool that only allows me to configure simple field queries, so I cannot use a complex script to perform. Any help would be greatly appreciated! Cheers... Cary

    Read the article

< Previous Page | 55 56 57 58 59 60 61 62 63 64 65 66  | Next Page >