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  • Amount of RAM for a web-server user.

    - by Janis Peisenieks
    I'm curently hosting my clients web-sites on some vps servers. What I would like to know, how many visitors can use the multiple web sites concurrently, before I need to migrate each of the sites to their seperate servers? So in laymans terms, how much RAM does a web-page user take on average? For example, how many concurrent visitors can I have on my server, running an Apache server, with 512mb RAM?

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  • Linux tools to choose suitable Cisco ASA 5500

    - by linuxcore
    I have a linux webhosting server which affects a high DDOS. I want to use Cisco ASA 5500 Series Adaptive Security Appliances to protect the linux server from this DDOS. I know there are many factors should you know before you choose the suitable hardware firewall like the amount of this DDOS and pps ..etc Please suggest a linux tools to measure those factors and to help me collect the required informations ( pps - amount of DDOS - concurrent connections and other factors ) Regards,

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  • FTP passive mode with limited port range?

    - by Phil Keeling
    I am running FileZilla FTP Server with passive mode enabled, and due to firewall constraints I have to limit the passive mode port range to only 6 ports. My question is how would FileZilla handle any situation where more than 6 concurrent FTP connections are active and want to passively upload a file. Would it queue the connections and prioritise them in a first in, first out manner? I'm not too familiar with FTP so any insight would be appreciated.

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  • What is the best log rotator for Python wsgi applications ?

    - by Low Kian Seong
    I am running a wsgi based application that has concurrent users accessing it. For my logs needs I tried logrotate but found that logrotate is not too friendly to Python applications, so I tried using RotatingFileHandler and even worse found my logs all chopped up and part of it went missing! I am considering ConcurrentRotatingFileHandler, my question is, has anyone out there experienced the same thing and better yet do you have any battle tested solution for Python wsgi, concurrently accessed applications?

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  • How would I recognize the "spoon-feeding problem" on a dynamic webapp server?

    - by Don Spaulding
    The "spoon-feeding problem", as it was recently explained to me, happens when connections to your application server are tied up feeding data across slow network connections to your clients. This makes sense to me and now I understand the importance of putting a highly-concurrent proxy in front of my app servers. My question is, how did the first person to recognize this problem figure it out? What *nix tools and troubleshooting techniques would help me to recognize this problem if I hadn't had it explained to me?

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  • A Versatile Physical Server

    - by Paul
    How does one judge potential memory and processor needs for linux web servers? Specifically, given: A Debian or Ubuntu OS Running a web server (apache2), and A database (MySQL), and A DNS server (bind), and Being used by up to 100 concurrent users, at some points each downloading high-resolution (0.5 to 1 MB) images via a web app. How much should one budget in terms of RAM, type of processor(s), and number of cores? Thanks!

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  • Apache: scope for environmental variables

    - by Anonymous
    While there's documentation available on Apache environmental variables, I can not find answer to one important question. Imagine I use rewrite rules to set environmental variable RewriteRule ... ... [E=something:1] What is the scope of "something" - global Apache server (this means "something" will be available for other request transactions), this request (means that "something" is only valid for THIS http request (and its related processing - but what's about internal redirects and other internal stuff - are they considered as THIS request, or another one?), and may be set differently within another (concurrent) request?

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  • A new Bursting patch for EBS Customers.

    - by ashish.shrivastava
    Patch 8594771 for Bursting functionality was released last week. The patch is for EBS R12 and 11i Customers. Following bugs have been fixed against this patch. 9550733 - DELIVERYREQUEST DOES NOT ACCEPT THE COMM IN EMAIL ADDRESS ALIAS. 9483876 : XML PUBLISHER REPORT BURSTING PROGRAM NOT DEBUGGING AFTER PATCH 7352374 9433950 : JAVA.UTIL.ZIP.ZIPEXCEPTION: ZIP FILE MUST HAVE AT LEAST ONE ENTRY 9285648 : XML PUBLISHER REPORT BURSTING PROGRAM IGNORES PORT NUMBER FOR WEBDAV DELIVERY 9269498 : NOT ABLE TO GENERATE ALL TYPES OF OUTPUTS WHILE BURSTING WITH JDE INTEGRATION. 9110360 : BURSTING USING BACKGROUND AND TITLE TAGS IN BURSTING CONTROL FILE FAILS 8937963 : BURSTING - UNABLE TO USE SPECIFIC FILENAME MORE THAN ONCE CAUSING ZIPEXCEPTION 8871779 : THE CONCURRENT LOG DOES NOT CONTAIN INFO AFTER PATCH 7352374 8594771 - BURSTING DOES NOT SUPPORT ESCAPE CHARACTERS LIKE "FIRST LAST "

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  • EBS: OPP Out of memory issue...

    - by ashish.shrivastava
    FO Processor is little more hungry for memory compare to other Java process. If XSLT scalable option is not set and the same time your RTF template is not well optimized definitely you are going to hit Out of memory exception while working with large volume of data. If the memory requirement is not too bad, you can set the OOP Heap size using following SQL queries. Check the current OPP JVM Heap size using following SQL query SQL select DEVELOPER_PARAMETERS from FND_CP_SERVICES where SERVICE_ID = (select MANAGER_TYPE from FND_CONCURRENT_QUEUES where CONCURRENT_QUEUE_NAME = 'FNDCPOPP' DEVELOPER_PARAMETERS ----------------------------------------------------- J:oracle.apps.fnd.cp.gsf.GSMServiceController:-mx512m Set the JVM Heap size using following SQL query SQL update FND_CP_SERVICES set DEVELOPER_PARAMETERS = 'J:oracle.apps.fnd.cp.gsf.GSMServiceController:-mx2048m' where SERVICE_ID = (select MANAGER_TYPE from FND_CONCURRENT_QUEUES where CONCURRENT_QUEUE_NAME = 'FNDCPOPP'); SQLCommit; . You need to restart the Concurrent Manager to make it effective. If this does not resolve the issue, You need to optimize RTF template and set the XSLT scalable option true.

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  • PHP OCI8 and Oracle 11g DRCP Connection Pooling in Pictures

    - by christopher.jones
    Here is a screen shot from a PHP OCI8 connection pooling demo that I like to run. It graphically shows how little database host memory is needed when using DRCP connection pooling with Oracle Database 11g. Migrating to DRCP can be as simple as starting the pool and changing the connection string in your PHP application. The script that generated the data for this graph was a simple "Parts" query application being run under various simulated user loads. I was running the database on a small Oracle Linux server with just 2G of memory. I used PHP OCI8 1.4. Apache is in pre-fork mode, as needed for PHP. Each graph has time on the horizontal access in arbitrary 'tick' time units. Click the image to see it full sized. Pooled connections Beginning with the top left graph, At tick time 65 I used Apache's 'ab' tool to start 100 concurrent 'users' running the application. These users connected to the database using DRCP: $c = oci_pconnect('phpdemo', 'welcome', 'myhost/orcl:pooled'); A second hundred DRCP users were added to the system at tick 80 and a final hundred users added at tick 100. At about tick 110 I stopped the test and restarted Apache. This closed all the connections. The bottom left graph shows the number of statements being executed by the database per second, with some spikes for background database activity and some variability for this small test. Each extra batch of users adds another 'step' of load to the system. Looking at the top right Server Process graph shows the database server processes doing the query work for each web user. As user load is added, the DRCP server pool increases (in green). The pool is initially at its default size 4 and quickly ramps up to about (I'm guessing) 35. At tick time 100 the pool increases to my configured maximum of 40 processes. Those 40 processes are doing the query work for all 300 web users. When I stopped the test at tick 110, the pooled processes remained open waiting for more users to connect. If I had left the test quiet for the DRCP 'inactivity_timeout' period (300 seconds by default), the pool would have shrunk back to 4 processes. Looking at the bottom right, you can see the amount of memory being consumed by the database. During the initial quiet period about 500M of memory was in use. The absolute number is just an indication of my particular DB configuration. As the number of pooled processes increases, each process needs more memory. You can see the shape of the memory graph echoes the Server Process graph above it. Each of the 300 web users will also need a few kilobytes but this is almost too small to see on the graph. Non-pooled connections Compare the DRCP case with using 'dedicated server' processes. At tick 140 I started 100 web users who did not use pooled connections: $c = oci_pconnect('phpdemo', 'welcome', 'myhost/orcl'); This connection string change is the only difference between the two tests. At ticks 155 and 165 I started two more batches of 100 simulated users each. At about tick 195 I stopped the user load but left Apache running. Apache then gradually returned to its quiescent state, killing idle httpd processes and producing the downward slope at the right of the graphs as the persistent database connection in each Apache process was closed. The Executions per Second graph on the bottom left shows the same step increases as for the earlier DRCP case. The database is handling this load. But look at the number of Server processes on the top right graph. There is now a one-to-one correspondence between Apache/PHP processes and DB server processes. Each PHP processes has one DB server processes dedicated to it. Hence the term 'dedicated server'. The memory required on the database is proportional to all those database server processes started. Almost all my system's memory was consumed. I doubt it would have coped with any more user load. Summary Oracle Database 11g DRCP connection pooling significantly reduces database host memory requirements allow more system memory to be allocated for the SGA and allowing the system to scale to handled thousands of concurrent PHP users. Even for small systems, using DRCP allows more web users to be active. More information about PHP and DRCP can be found in the PHP Scalability and High Availability chapter of The Underground PHP and Oracle Manual.

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  • How would you advocate not using a shared spreadsheet to track bugs / issues ?

    - by Sylvain Defresne
    In our company, the developers want to use a proper bug tracking tool to manager issues in our application. The management however insists on using a shared spreadsheet (formeerly a shared excel file, now a spreadsheet on a web base solution allowing concurrent access). Their argument is that the spreadsheet allow them to have a more highlevel view of the state of the project as they can see how many bugs are open with a quick glance. This also allow them to see who is working on each bug, and get estimation of the time required to close them all (as developer are required to fill time estimation of the bug they are working on). As you can understand, this is not really practical to use for the developers (bug tracking software were invented for a reason). So how can I advocate bug tracking software to ease the work of the developer ? As a bonus, which software would you recommend that would allow the management to be able to get their feedbacks (number of bugs opens, who is working on them, time estimation) with a high level view ?

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  • O&rsquo;Reilly Deal of the Day 6/August/2014 - Professional C# 5.0 and .NET 4.5.1

    - by TATWORTH
    Originally posted on: http://geekswithblogs.net/TATWORTH/archive/2014/08/06/orsquoreilly-deal-of-the-day-6august2014---professional-c-5.0.aspxToday’s half-price deal from O’Reilly at http://shop.oreilly.com/product/9781118833032.do?code=MSDEAL, is Professional C# 5.0 and .NET 4.5.1. “Written by a dream team of .NET experts, Professional C# 5.0 and .NET 4.5.1 includes everything developers need to work with C#, the language of choice for .NET applications. This book is perfect for both experienced C# programmers looking to sharpen their skills and professional developers who are using C# for the first time. The authors deliver unparalleled coverage of Visual Studio 2013 and .NET Framework 4.5.1 additions, as well as new test-driven development and concurrent programming features. Source code for all the examples are available for download, so you can start writing Windows desktop, Windows Store apps, and ASP.NET web applications immediately.”

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  • How big can my SharePoint 2010 installation be?

    - by Sahil Malik
    Ad:: SharePoint 2007 Training in .NET 3.5 technologies (more information). 3 years ago, I had published “How big can my SharePoint 2007 installation be?” Well, SharePoint 2010 has significant under the covers improvements. So, how big can your SharePoint 2010 installation be? There are three kinds of limits you should know about Hard limits that cannot be exceeded by design. Configurable that are, well configurable – but the default values are set for a pretty good reason, so if you need to tweak, plan and understand before you tweak. Soft limits, you can exceed them, but it is not recommended that you do. Before you read any of the limits, read these two important disclaimers - 1. The limit depends on what you’re doing. So, don’t take the below as gospel, the reality depends on your situation. 2. There are many additional considerations in planning your SharePoint solution scalability and performance, besides just the below. So with those in mind, here goes.   Hard Limits - Zones per web app 5 RBS NAS performance Time to first byte of any response from NAS must be less than 20 milliseconds List row size 8000 bytes driven by how SP stores list items internally Max file size 2GB (default is 50MB, configurable). RBS does not increase this limit. Search metadata properties 10,000 per item crawled (pretty damn high, you’ll never need to worry about it). Max # of concurrent in-memory enterprise content types 5000 per web server, per tenant Max # of external system connections 500 per web server PerformancePoint services using Excel services as a datasource No single query can fetch more than 1 million excel cells Office Web Apps Renders One doc per second, per CPU core, per Application server, limited to a maximum of 8 cores.   Configurable Limits - Row Size Limit 6, configurable via SPWebApplication.MaxListItemRowStorage property List view lookup 8 join operations per query Max number of list items that a single operation can process at one time in normal hours 5000 Configurable via SPWebApplication.MaxItemsPerThrottledOperation   Also you get a warning at 3000, which is configurable via SPWebApplication.MaxItemsPerThrottledOperationWarningLevel   In addition, throttle overrides can be requested, throttle overrides can be disabled, and time windows can be set when throttle is disabled. Max number of list items for administrators that a single operation can process at one time in normal hours 20000 Configurable via SPWebApplication.MaxItemsPerThrottledOperationOverride Enumerating subsites 2000 Word and Powerpoint co-authoring simultaneous editors 10 (Hard limit is 99). # of webparts on a page 25 Search Crawl DBs per search service app 10 Items per crawl db 25 million Search Keywords 200 per site collection. There is a max limit of 5000, which can then be modified by editing the web.config/client.config. Concurrent # of workflows on a content db 15. Workflows running in the timer service are not counted in this limit. Further workflows are queued. Can be configured via the Set-SPFarmConfig powershell commandlet. Number of events picked by the workflow timer job and delivered to workflows 100. You can increase this limit by running additional instances of the workflow timer service. Visio services file size 50MB Visio web drawing recalculation timeout 120 seconds Configurable via – Powershell commandlet Set-SPVisioPerformance Visio services minimum and maximum cache age for data connected diagrams 0 to 24 hours. Default is 60 minutes. Configurable via – Powershell commandlet Set-SPVisioPerformance   Soft Limits - Content Databases 300 per web app Application Pools 10 per web server Managed Paths 20 per web app Content Database Size 200GB per Content DB Size of 1 site collection 100GB # of sites in a site collection 250,000 Documents in a library 30 Million, with nesting. Depends heavily on type and usage and size of documents. Items 30 million. Depends heavily on usage of items. SPGroups one SPUser can be in 5000 Users in a site collection 2 million, depends on UI, nesting, containers and underlying user store AD Principals in a SPGroup 5000 SPGroups in a site collection 10000 Search Service Instances 20 Indexed Items in Search 100 million Crawl Log entries 100 million Search Alerts 1 million per search application Search Crawled Properties 1/2 million URL removals in search 100 removals per operation User Profiles 2 million per service application Social Tags 500 million per social database Comment on the article ....

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  • Quick ways to boost performance and scalability of ASP.NET, WCF and Desktop Clients

    - by oazabir
    There are some simple configuration changes that you can make on machine.config and IIS to give your web applications significant performance boost. These are simple harmless changes but makes a lot of difference in terms of scalability. By tweaking system.net changes, you can increase the number of parallel calls that can be made from the services hosted on your servers as well as on desktop computers and thus increase scalability. By changing WCF throttling config you can increase number of simultaneous calls WCF can accept and thus make most use of your hardware power. By changing ASP.NET process model, you can increase number of concurrent requests that can be served by your website. And finally by turning on IIS caching and dynamic compression, you can dramatically increase the page download speed on browsers and and overall responsiveness of your applications. Read the CodeProject article for more details. http://www.codeproject.com/KB/webservices/quickwins.aspx Please vote for me if you find the article useful.

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  • F# for the C# Programmer

    - by mbcrump
    Are you a C# Programmer and can’t make it past a day without seeing or hearing someone mention F#?  Today, I’m going to walk you through your first F# application and give you a brief introduction to the language. Sit back this will only take about 20 minutes. Introduction Microsoft's F# programming language is a functional language for the .NET framework that was originally developed at Microsoft Research Cambridge by Don Syme. In October 2007, the senior vice president of the developer division at Microsoft announced that F# was being officially productized to become a fully supported .NET language and professional developers were hired to create a team of around ten people to build the product version. In September 2008, Microsoft released the first Community Technology Preview (CTP), an official beta release, of the F# distribution . In December 2008, Microsoft announced that the success of this CTP had encouraged them to escalate F# and it is now will now be shipped as one of the core languages in Visual Studio 2010 , alongside C++, C# 4.0 and VB. The F# programming language incorporates many state-of-the-art features from programming language research and ossifies them in an industrial strength implementation that promises to revolutionize interactive, parallel and concurrent programming. Advantages of F# F# is the world's first language to combine all of the following features: Type inference: types are inferred by the compiler and generic definitions are created automatically. Algebraic data types: a succinct way to represent trees. Pattern matching: a comprehensible and efficient way to dissect data structures. Active patterns: pattern matching over foreign data structures. Interactive sessions: as easy to use as Python and Mathematica. High performance JIT compilation to native code: as fast as C#. Rich data structures: lists and arrays built into the language with syntactic support. Functional programming: first-class functions and tail calls. Expressive static type system: finds bugs during compilation and provides machine-verified documentation. Sequence expressions: interrogate huge data sets efficiently. Asynchronous workflows: syntactic support for monadic style concurrent programming with cancellations. Industrial-strength IDE support: multithreaded debugging, and graphical throwback of inferred types and documentation. Commerce friendly design and a viable commercial market. Lets try a short program in C# then F# to understand the differences. Using C#: Create a variable and output the value to the console window: Sample Program. using System;   namespace ConsoleApplication9 {     class Program     {         static void Main(string[] args)         {             var a = 2;             Console.WriteLine(a);             Console.ReadLine();         }     } } A breeze right? 14 Lines of code. We could have condensed it a bit by removing the “using” statment and tossing the namespace. But this is the typical C# program. Using F#: Create a variable and output the value to the console window: To start, open Visual Studio 2010 or Visual Studio 2008. Note: If using VS2008, then please download the SDK first before getting started. If you are using VS2010 then you are already setup and ready to go. So, click File-> New Project –> Other Languages –> Visual F# –> Windows –> F# Application. You will get the screen below. Go ahead and enter a name and click OK. Now, you will notice that the Solution Explorer contains the following: Double click the Program.fs and enter the following information. Hit F5 and it should run successfully. Sample Program. open System let a = 2        Console.WriteLine a As Shown below: Hmm, what? F# did the same thing in 3 lines of code. Show me the interactive evaluation that I keep hearing about. The F# development environment for Visual Studio 2010 provides two different modes of execution for F# code: Batch compilation to a .NET executable or DLL. (This was accomplished above). Interactive evaluation. (Demo is below) The interactive session provides a > prompt, requires a double semicolon ;; identifier at the end of a code snippet to force evaluation, and returns the names (if any) and types of resulting definitions and values. To access the F# prompt, in VS2010 Goto View –> Other Window then F# Interactive. Once you have the interactive window type in the following expression: 2+3;; as shown in the screenshot below: I hope this guide helps you get started with the language, please check out the following books for further information. F# Books for further reading   Foundations of F# Author: Robert Pickering An introduction to functional programming with F#. Including many samples, this book walks through the features of the F# language and libraries, and covers many of the .NET Framework features which can be leveraged with F#.       Functional Programming for the Real World: With Examples in F# and C# Authors: Tomas Petricek and Jon Skeet An introduction to functional programming for existing C# developers written by Tomas Petricek and Jon Skeet. This book explains the core principles using both C# and F#, shows how to use functional ideas when designing .NET applications and presents practical examples such as design of domain specific language, development of multi-core applications and programming of reactive applications.

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  • Un écran LCD 3D Ready pour 1499 euros en avril, Samsung investit le marché

    Mise à jour du 09.03.2010 par Katleen Un écran LCD 3D Ready pour 1499 euros en avril, Samsung investit le marché Panasonic s'est fait damer le pion par Samsung, qui vient d'annoncer une sortie de ses premiers téléviseurs 3D Ready en France pour avril 2010, soit un mois en avance sur son concurrent. Une douzaine de modèles sortiront dans cette gamme, toutes technologies confondues (LCD, LED, plasma...). L'appareil le moins cher sera un LCD 3D Ready de 40 pouces à 1499 euros. Les lunettes actives permettant denner des images en trois dimensions seront a acheter en sus, pour 200 euros les 4 paires (offre de lancement). Selon le constructeur coréen, une cinquantaine d...

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  • Advices and strategies for browser compatibility on web applications into a corporate environment

    - by TiagoBrenck
    With the new CSS 3 and HTML 5 tecnology, the web applications gained a lot of new tools for a better UI(user interface) interaction, beautifull templates and even responsive layout to fit into tablets and smartphones. Within a corporate environment, those new tecnologies are required so the company can "follow" the IT evolution and their concurrent, but they also want that those new web applications supports old browsers. How to deal with this situation? By one side we are asked to follow the news and IT evolutions, create responsive layouts and use a lot of cool jQuery's plugins. And by the other side, we are asked to support old browsers that doesn't support those new responsive features, plugins or components. I would like advices and strategies to create "modern" web applications that are also supported on old browsers. How does your company deal with this situation? Is it possible to have the same web application running good and beauty on old browsers, and responsive, interactive on actual browsers?

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  • Gilda Garretón, a Java Developer and Parallelism Computing Researcher

    - by Yolande
    In a new interview titled “Gilda Garretón, a Java Developer and Parallelism Computing Research,” Garretón shares her first-hand experience developing with Java and Java 7 for very large-scale integration (VLSI) of computer-aided design (CAD). Garretón gives an insightful overview of how Java is contributing to the parallelism development and to the Electric VLSI Design Systems, an open source VLSI CAD application used as a research platform for new CAD algorithms as well as the research flow for hardware test chips.  Garretón considers that parallelism programming is hard and complex, yet important developments are taking place.  "With the addition of the concurrent package in Java SE 6 and the Fork/Join feature in Java SE 7, developers have a chance to rely more on existing frameworks and dedicate more time to the essence of their parallel algorithms." Read the full article here  

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  • Clarification about Event Producer in StreamInsight

    - by sandy
    I need a small clarification about streamInsight, I know by doc's that StreamInsight can handle multiple concurrent Events. But will the event producer be a separate function, for ex: I need to watch a folder for new Files becoz all my sensors il write readings every day in a new file in particular drive. Method 1: FileSystemWatcher: These is the traditional approach where we write a service using FileSystemWatcher to watch a folder for new files,etc.. Upon receiving event from FileSystemWatcher il perform some operations on these files. How to do these using streamInsight??? I came know that using IObservable i can push events to StreamInsight. But is there anything to watch folder is sreamInsight like FileSystemWatcher. OR In order to raise events to streamInsight do we need to use FileSystemWacther? Any suggestion regarding these is highly appreciated. Thank in Advance

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  • Strategies for browser compatibility on web applications in a corporate environment

    - by TiagoBrenck
    With the new CSS 3 and HTML 5 technology, web applications have gained a lot of new tools for a better UI (user interface) interaction, beautiful templates and even responsive layout to fit into tablets and smartphones. Within a corporate environment, those new technologies are required so the company can "follow" the IT evolution and their concurrent, but they also want that those new web applications supports old browsers. How should I deal with this situation? By one side we are asked to follow the the evolution of technology, create responsive layouts and use a lot of cool jQuery plugins. On the other hand, we are asked to support old browsers that do not support those new responsive features, plugins or components. I would like advice and strategies on how to create "modern" web applications that are also supported on old browsers. How does your company deal with this situation? Is it possible to have the same web application run well and beautifully on old browsers, and be responsive and interactive on newer browsers?

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  • What do you think of a performance engineer should have?

    - by Vance
    I believe performance tuning (or even testing) is one the most challenging for an engineer. Well, in lots of company, this is the lowest priority than others "important" thing. My purpose of opening this post is to know what do you think*good* performance engineer should have. I can list some things like: Solid database,programming knowledge. Do single thread performance testing. Good knowledge of using the load generator tools to simulate the concurrent loads. Use different tools to monitor/measure the app/db server performance status Understand and can debug the codes. Even tune the codes. Any more ideas are always appreciated!

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  • DevConnections Conference

    - by ScottGu
    The excellent DevConnections conference will be held in Florida later this month (March 27th to 30th).  DevConnections features multiple concurrent tracks – including ASP.NET Connections, Silverlight Connections, Visual Studio Connections, SQL Server Connections, and SharePoint Connections. I’ll be doing a keynote on the first day, and there will be dozens of fantastic talks that week by some of the best presenters in the .NET community.  You can learn more about the conference here. I highly recommend the conference – and hope to meet up with some of you there! Scott P.S. Use the discount code “DevCon1” to save $200 when registering.

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  • Host And Expose Application to local small network

    - by tartak
    I developed a little application (web application) using JavaEE+MySql. I try to keep some data and .. from time to time to get some reports using my data. My problem is I have to access this application from 4-5 computers in the office. They are connected through a switch. It's a typical small office network, nothing fancy. I need some advice on how to do this. I mean for a small application with no external communication is it mandatory to use an Apache machine? I'd use a simple Tomcat container on the "server machine" (which is my computer, a windows machine) and .. basically .. I would like to permit the access to my colleagues also. I don't have any knowledge about concurrency (I know mysql permits concurrent access) so I would like some configuration tips also.

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  • .NET 4: &ldquo;Slim&rdquo;-style performance boost!

    - by Vitus
    RTM version of .NET 4 and Visual Studio 2010 is available, and now we can do some test with it. Parallel Extensions is one of the most valuable part of .NET 4.0. It’s a set of good tools for easily consuming multicore hardware power. And it also contains some “upgraded” sync primitives – Slim-version. For example, it include updated variant of widely known ManualResetEvent. For people, who don’t know about it: you can sync concurrency execution of some pieces of code with this sync primitive. Instance of ManualResetEvent can be in 2 states: signaled and non-signaled. Transition between it possible by Set() and Reset() methods call. Some shortly explanation: Thread 1 Thread 2 Time mre.Reset(); mre.WaitOne(); //code execution 0 //wating //code execution 1 //wating //code execution 2 //wating //code execution 3 //wating mre.Set(); 4 //code execution //… 5 Upgraded version of this primitive is ManualResetEventSlim. The idea in decreasing performance cost in case, when only 1 thread use it. Main concept in the “hybrid sync schema”, which can be done as following:   internal sealed class SimpleHybridLock : IDisposable { private Int32 m_waiters = 0; private AutoResetEvent m_waiterLock = new AutoResetEvent(false);   public void Enter() { if (Interlocked.Increment(ref m_waiters) == 1) return; m_waiterLock.WaitOne(); }   public void Leave() { if (Interlocked.Decrement(ref m_waiters) == 0) return; m_waiterLock.Set(); }   public void Dispose() { m_waiterLock.Dispose(); } } It’s a sample from Jeffry Richter’s book “CLR via C#”, 3rd edition. Primitive SimpleHybridLock have two public methods: Enter() and Leave(). You can put your concurrency-critical code between calls of these methods, and it would executed in only one thread at the moment. Code is really simple: first thread, called Enter(), increase counter. Second thread also increase counter, and suspend while m_waiterLock is not signaled. So, if we don’t have concurrent access to our lock, “heavy” methods WaitOne() and Set() will not called. It’s can give some performance bonus. ManualResetEvent use the similar idea. Of course, it have more “smart” technics inside, like a checking of recursive calls, and so on. I want to know a real difference between classic ManualResetEvent realization, and new –Slim. I wrote a simple “benchmark”: class Program { static void Main(string[] args) { ManualResetEventSlim mres = new ManualResetEventSlim(false); ManualResetEventSlim mres2 = new ManualResetEventSlim(false);   ManualResetEvent mre = new ManualResetEvent(false);   long total = 0; int COUNT = 50;   for (int i = 0; i < COUNT; i++) { mres2.Reset(); Stopwatch sw = Stopwatch.StartNew();   ThreadPool.QueueUserWorkItem((obj) => { //Method(mres, true); Method2(mre, true); mres2.Set(); }); //Method(mres, false); Method2(mre, false);   mres2.Wait(); sw.Stop();   Console.WriteLine("Pass {0}: {1} ms", i, sw.ElapsedMilliseconds); total += sw.ElapsedMilliseconds; }   Console.WriteLine(); Console.WriteLine("==============================="); Console.WriteLine("Done in average=" + total / (double)COUNT); Console.ReadLine(); }   private static void Method(ManualResetEventSlim mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } }   private static void Method2(ManualResetEvent mre, bool value) { for (int i = 0; i < 9000000; i++) { if (value) { mre.Set(); } else { mre.Reset(); } } } } I use 2 concurrent thread (the main thread and one from thread pool) for setting and resetting ManualResetEvents, and try to run test COUNT times, and calculate average execution time. Here is the results (I get it on my dual core notebook with T7250 CPU and Windows 7 x64): ManualResetEvent ManualResetEventSlim Difference is obvious and serious – in 10 times! So, I think preferable way is using ManualResetEventSlim, because not always on calling Set() and Reset() will be called “heavy” methods for working with Windows kernel-mode objects. It’s a small and nice improvement! ;)

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