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  • Unidirectional synchronization and admin back-end

    - by HTF
    I have Wordpress installation on two web nodes (load balancing/failover). There is unidirectional synchronization from server A to server B so any updates must occur on the first web node. I have a problem with Wordpress admin side. I'm using Nginx and the initial plan was to create rewrite rule from domain.com/wp-admin to wpadmin.domain.com - pointing to the first node. The problem is that the Wordpress installation can be access only via main domain and without extra subdomain there is no distinction between both web servers for the rewrite rule. Could you please advise if there is any other solution in this case. Regards

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  • Optional Member Objects

    - by David Relihan
    Okay, so you have a load of methods sprinkled around your systems main class. So you do the right thing and refactor by creating a new class and perform move method(s) into a new class. The new class has a single responsibility and all is right with the world again: class Feature { public: Feature(){}; void doSomething(); void doSomething1(); void doSomething2(); }; So now your original class has a member variable of type object: Feature _feature; Which you will call in the main class. Now if you do this many times, you will have many member-objects in your main class. Now these features may or not be required based on configuration so in a way it's costly having all these objects that may or not be needed. Can anyone suggest a way of improving this? At the moment I plan to test in the newly created class if the feature is enabled - so the when a call is made to method I will return if it is not enabled. I could have a pointer to the object and then only call new if feature is enabled - but this means I will have to test before I call a method on it which would be potentially dangerous and not very readable. Would having an auto_ptr to the object improve things: auto_ptr<Feature> feature; Or am I still paying the cost of object invokation even though the object may\or may not be required. BTW - I don't think this is premeature optimisation - I just want to consider the possibilites.

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  • Bacula Director and Storage in LAN

    - by B14D3
    I have two networks LAN and DMZ.. Machines in DMZ are accesible from internet ( only over http). In LAN I have servers that see all LAN and all DMZ machines but machinse from DMZ don't see any LAN servers. Machines in LAN have access only to all LAN and DMZ, no direct access to internet and no access from internet. DMZ <------ LAN DMZ ----X--->LAN I'm planning to configure Bacula as major backup system. My plan is to install Bacula Director and Storage deamon on the same server in LAN for safety reasons. So my question is: Will this configuration work, is it posible for bacula director and storage deamon installed on server in LAN to makes backup servers that are in my DMZ? Or in this network configuration Bacula should be in DMZ? (If yes will I can backup with it servers in LAN ?)

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  • Getting Started with Ruby & Ruby on Rails

    - by JakeTheSnake
    Some background: I'm a jack-of-all traits, one of which is programming. I learned VB6 through Excel and PHP for creating websites and so far it's worked out just fine for me. I'm not CS major or even mathematically inclined - logic is what interests me. Current status: I'm willing to learn new and more powerful languages; my first foray into such a route is learning Ruby. I went to the main Ruby website and did the interactive intro. (by the way, I'm currently getting redirected to google.com when I try the link...it's happening to other websites as well...is my computer infected?) I liked what I learned and wanted to get started using Ruby to create websites. I downloaded InstantRails and installed it; everything so far has been fine - the program starts up just fine, and I can test some Ruby code in the console. However my troubles begin when I try and view a web page with Ruby code present. Lastly, my problem: As in PHP, I can browse to the .php file directly and through using PHP tags and some simple 'echo' statements I can be on my way in making dynamic web pages. However with the InstantRails app working, accessing a .rb or .rhtml page doesn't produce similar results. I made a simple text file named 'test.rb' and put basic HTML tags in there (html, head, body) and the Ruby tags <%= and % with some ruby code inside. The web page actually shows the tags and the code - as if it's all just plain HTML. I take it Ruby isn't parsing the page before it is displayed to the user, but this is where my lack of understanding of the Ruby environment stops me short. Where do I go from here?

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  • How do I pass a LuaTable between two Lua states using LuaInterface?

    - by user316675
    I've been trying to pass a LuaTable class between two Lua states, like so: LuaManager L1 = new Lua(); LuaManager L2 = new Lua(); LuaTable table = L1.DoString("return {apple = 25}")[0]; L2["tbl"] = table; double results = L2.DoString("return tbl[\"apple\"]")[0]; Assert.AreEqual(25.0, results); The above test fails; I receive a return value of nil. Using the Immediate Window confirms that "table" is a non-null object, and that table["apple"] returns 25; it's something that's being lost in translation to L2. Interestingly, when the object is loaded back into the same state, the test works, like so: //Succeeds LuaManager lua = new Lua(); LuaTable table = lua.DoString("return {apple = 25}")[0]; lua["tbl"] = table; double results = lua.DoString("return tbl[\"apple\"]")[0]; Assert.AreEqual(25.0, results); How can I safely pass the LuaTables without hassles? Thanks in advance!

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  • CSS being ignored in IE & FFox but not Chrome

    - by Grant
    Hi, i am styling a navigation menu using the following css. I have found that it works perfectly in chrome but absolutely none of the css is beign applied in firefox or IE. Is there something obvious that i havent done or have done here? <style type="text/css"> #ddm { margin: 0; padding: 0; } #ddm li { float: left; list-style: none; font: 8pt Tahoma, Geneva, sans-serif; } #ddm li a { display: block; padding: 5px 12px; text-decoration: none; border-right: 1px solid white; width: 70px; white-space: nowrap; color:Red; border: none; } #ddm li a:hover { color:White; background-color:#444444; } #ddm li ul { margin: 0; padding: 0; position: absolute; visibility: hidden; } #ddm li ul li { float: none; display: inline } #ddm li ul li a { width: auto; } #ddm li ul li a:hover { } </style> <ul id="ddm"> <li> <ul> <li><a href="#">test 1</a></li> <li><a href="#">test 2</a></li> </ul> </li> </ul>

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  • String Connection Issue

    - by Nano HE
    Hi, Could you please have a look at my code below. #!C:\Perl\bin\perl.exe use strict; use warnings; use Data::Dumper; my $fh = \*DATA; my $str1 = "listBox1.Items.Add(\""; my $str2 = "\")\;"; while(my $line = <$fh>) { $line=~s/^\s+//g; print $str1.$line.$str2; chomp($line); } __DATA__ Hello World Output: D:\learning\perl>test.pl listBox1.Items.Add("Hello ");listBox1.Items.Add("World "); D:\learning\perl> Style error. I want the style below. Is ther anything wrong about my code? thanks. D:\learning\perl>test.pl listBox1.Items.Add("Hello"); listBox1.Items.Add("World"); D:\learning\perl>

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  • Service Browser for AMF calls (Flex to Java)

    - by Tehsin
    Has anyone used or is aware of a service browser to test AMF calls? I am looking for a tool similar to ZamfBrowser ( http://www.zamfbrowser.org ), but one that works for the Java environment. ZamfBrowser is geared towards AMFPHP. The idea here is to provide a service browser, that allows developers to test Java services using the AMF protocol, without having to go through the Flex UI all the time. There has got to be something out there already for this, but I can't seem to locate anything..... It's kind of funny and strange that a service browser exists for AMFPHP but not for regular AMF calls in a Java environment. I would imagine something exists under Blaze or LCDS? ... Trying to find it in the docs but can't seem to find anything .... The best alternative I can think of at the moment is to use FlexMonkey to record stuff, and then to simulate it using that....which is okay I guess but still sucks because you have to go in and create the Flex UI first, whereas with something like ZamfBrowser, you simply point it at the service calls, it tells the server-side developers if their code works, etc. generates the required as3 classes for you... and makes the integration process much easier in a large team. Any help or insight would be appreciated :) Thanks!

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  • html5 cache -> "network: *" doesn't work

    - by Greg
    Hello all, I am trying a simple test with the html 5 cache. Here is a simple web page : <!DOCTYPE html> <html manifest="test.manifest"> <head> </head> <body> <img src="http://www.somewebsite.com/picture.jpg"/> </body> </html> With the following manifest : CACHE MANIFEST #v0.1 NETWORK: http://www.somewebsite.com/ This work fine, the picture is displayed. My problem is that I won't be able to know from where the picture will come. Here comes the online whitelist wildcard flag, that is supposed to solve my problem. But with the manifest : CACHE MANIFEST #v0.1 NETWORK: * The image is not displayed (tested on safari / safari mobile / firefox). What is not working ? Is there another way to turn the online whitelist wildcard flag on ?

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  • How to fill in the network line in the ubuntu interfaces config file?

    - by matnagel
    I have to configure an ubuntu hardy server network interface. The service hoster told me that this is the network data for the machine: IP Range: 111.111.200.74 to 111.111.200.78 Netmask: 255.255.255.248 Broadcast: 111.111.200.79 Gateway: 111.111.200.73 Subnet: 111.111.200.72/29 I am only using the first IP address. I will update the /etc/hosts file with 111.111.200.74, but I am still unsure how the /etc/network/interfaces file should be. This is my plan: auto lo iface lo inet loopback auto eth0 iface eth0 inet static address 111.111.200.74 netmask 255.255.255.248 network 111.111.200.??? broadcast 111.111.200.79 gateway 111.111.200.73 As you can see I don't know how to build the network line. How would I calculate the data for the network line and what is the result? (I changed the first 2 octets of the subnet, they are not "111.111" in the real setup.)

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  • Passing parameters to eventListener function

    - by bryan sammon
    I have this function check(e) that I'd like to be able to pass parameters from test() when I add it to the eventListener. Is this possible? Like say to get the mainlink variable to pass through the parameters. Is this even good to do? I put the javascript below, I also have it on jsbin: http://jsbin.com/ujahe3/9/edit function test() { if (!document.getElementById('myid')) { var mainlink = document.getElementById('mainlink'); var newElem = document.createElement('span'); mainlink.appendChild(newElem); var linkElemAttrib = document.createAttribute('id'); linkElemAttrib.value = "myid"; newElem.setAttributeNode(linkElemAttrib); var linkElem = document.createElement('a'); newElem.appendChild(linkElem); var linkElemAttrib = document.createAttribute('href'); linkElemAttrib.value = "jsbin.com"; linkElem.setAttributeNode(linkElemAttrib); var linkElemText = document.createTextNode('new click me'); linkElem.appendChild(linkElemText); if (document.addEventListener) { document.addEventListener('click', check/*(WOULD LIKE TO PASS PARAMETERS HERE)*/, false); }; }; }; function check(e) { if (document.getElementById('myid')) { if (document.getElementById('myid').parentNode === document.getElementById('mainlink')) { var target = (e && e.target) || (event && event.srcElement); var obj = document.getElementById('mainlink'); if (target!= obj) { obj.removeChild(obj.lastChild); }; }; }; };

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  • How to select the first property with unknown name and first item from array in JSON

    - by Oscar Godson
    I actually have two questions, both are probably simple, but for some odd reason I cant figure it out... I've worked with JSON 100s of times before too! but here is the JSON in question: {"69256":{ "streaminfo":{ "stream_ID":"1025", "sourceowner_ID":"2", "sourceowner_avatar":"http:\/\/content.nozzlmedia.com\/images\/sourceowner_avatar2.jpg", "sourceownertype_ID":"1", "stream_name":"Twitter", "streamtype":"Social media" "appsarray":[] }, "item":{ "headline":"Charboy", "main_image":"http:\/\/content.nozzlmedia.com\/images\/author_avatar173212.jpg", "summary":"ate a tomato and avocado for dinner...", "nozzl_captured":"2010-05-12 23:02:12", "geoarray":[{ "state":"OR", "county":"Multnomah", "city":"Portland", "neighborhood":"Downtown", "zip":"97205", "street":"462 SW 11th Ave", "latitude":"45.5219", "longitude":"-122.682" }], "full_content":"ate a tomato and avocado for dinner tonight. such tasty foods. just enjoyable.", "body_text":"ate a tomato and avocado for dinner tonight. such tasty foods. just enjoyable.", "author_name":"Charboy", "author_avatar":"http:\/\/content.nozzlmedia.com\/images\/author_avatar173212.jpg", "fulltext_url":"http:\/\/twitter.com\/charboy\/statuses\/13889868936", "leftovers":{ "twitter_id":"tag:search.twitter.com,2005:13889868936", "date":"2010-05-13T02:59:59Z", "location":"iPhone: 45.521866,-122.682262" }, "wordarray":{ "0":"ate", "1":"tomato", "2":"avocado", "3":"dinner", "4":"tonight", "5":"tasty", "6":"foods", "7":"just", "8":"enjoyable", "9":"Charboy", "11":"Twitter", "13":"state:OR", "14":"county:Multnomah, OR", "15":"city:Portland, OR", "16":"neighborhood:Downtown", "17":"zip:97205" } } } } Question 1: How do I loop through each item (69256) when the number is random? e.g. item 1 is 123, item2 is 646? Like, for example, a normal JSON feed would have something like: {'item':{'blah':'lorem'},'item':{'blah':'ipsum'}} the JS would be like console.log(item.blah) to return lorem then ipsum in a loop How do I do it when i dont know the first item of the object? Question 2: How do I select items from the geoarray object? I tried: json.test.item.geoarray.latitude and json.test.item.geoarray['latitude']

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  • Transfer nearly an entire file system to a fresh install as smoothly as possible

    - by Xander
    I've got a friend who needs his computer working in just a few hours. His files are safe, however, he managed to corrupt his main install of Windows 7. My plan is to go in with a Linux disk, copy his C:\ do a backup drive I've got and then reinstall. Restoring many of his files will be pretty simple (such as documents and such), however, things such as applications won't transfer as easily. Is there any easy way to transfer applications such as MS Office (which he needs in the morning) or other commercial software packages without having to go through the hassle of locating the keys and reinstalling them completely? I don't think just moving them over will work just because of the fact that I'm sure much of that is stored in the registry (validation stuff and such). Anyways, quick responses would be super nice! Also, additional help would be great!

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  • How to configure Eclipse XML formatting?

    - by tputkonen
    I would like to change the way Eclipse formats XML files. For example, if I have in pom.xml file a section as follows: <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> After ctrl+shift+f it will look like: <dependency> <groupId> junit </groupId> <artifactId> junit </artifactId> <version> 3.8.1 </version> <scope> test </scope> </dependency> I prefer the first version, so how to configure Eclipse to format XML files to look like that?

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  • curl: downloading from dynamic url

    - by adam n
    I'm trying to download an html file with curl in bash. Like this site: http://www.registrar.ucla.edu/schedule/detselect.aspx?termsel=10S&subareasel=PHYSICS&idxcrs=0001B+++ When I download it manually, it works fine. However, when i try and run my script through crontab, the output html file is very small and just says "Object moved to here." with a broken link. Does this have something to do with the sparse environment the crontab commands run it? I found this question: http://stackoverflow.com/questions/1279340/php-ssl-curl-object-moved-error but i'm using bash, not php. What are the equivalent command line options or variables to set to fix this problem in bash? (I want to do this with curl, not wget) Edit: well, sometimes downloading the file manually (via interactive shell) works, but sometimes it doesn't (I still get the "Object moved here" message). So it may not be a a specifically be a problem with cron's environment, but with curl itself. the cron entry: * * * * * ~/.class/test.sh >> ~/.class/test_out 2>&1 test.sh: #! /bin/bash PATH=/usr/local/bin:/usr/bin:/bin:/sbin cd ~/.class course="physics 1b" url="http://www.registrar.ucla.edu/schedule/detselect.aspx?termsel=10S<URL>subareasel=PHYSICS<URL>idxcrs=0001B+++" curl "$url" -sLo "$course".html --max-redirs 5 As I was searching around on google, someone suggested that the problem might happen because there are parameters in the url. (Because it is a dynamic url?)

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  • Spoof user agent for GoGo Inflight Internet?

    - by AndyL
    Is it possible to trick the GoGo Inflight WiFi on airlines into thinking that you have a mobile device instead of a laptop? It seems like most airlines that offer in flight wireless these days use GoGo. They offer different pricing for mobile and laptops. It seems like they are checking the browser's user agent. Out of curiosity, is it possible to use a Firefox extension like this one to spoof the user-agent and allow a laptop to access the internet under a GoGo mobile plan? How would GoGo handle something like an IMAP email client, like Thunderbird. Do IMAP clients have a user-agent field as well that would normally identify whether the mail client is running on a laptop or mobile device?

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  • Configuring mod_rewrite and mod_jk for Apache 2.2 and JBoss 4.2.3

    - by The Pretender
    Hello! My problem is as follows: I have JBoss 4.2.3 application server with AJP 1.3 connector running on one host under Windows (192.168.1.2 for my test environment) and Apache 2.2.14 running on another FreeBSD box (192.168.1.10). Apache acts as a "front gate" for all requests and sends them to JBoss via mod_jk. Everything was working fine until I had to do some SEO optimizations. These optimizations include SEF urls, so i decided to use mod_rewrite for Apache to alter requests before they are sent to JBoss. Basically, I nedd to implement 2 rules: Redirect old rules like "http://hostname/directory/" to "http://hostname/" with permanent redirect Forward urls like "http://hostname/wtf/123/" to "http://hostname/wtf/view.htm?id=123" so that end user doesn't see the "ugly" URL (the actual rewrite). Here is my Apache config for test virtual host: <VirtualHost *:80> ServerAdmin [email protected] DocumentRoot "/usr/local/www/dummy" ServerName 192.168.1.10 <IfModule mod_rewrite.c> RewriteEngine On RewriteRule /directory/(.*) /$1 [R=permanent,L] RewriteRule ^/([^/]+)/([0-9]+)/?$ /$1/view.htm?id=$2 </IfModule> JkMount /* jsp-hostname ErrorLog "/var/log/dummy-host.example.com-error_log" CustomLog "/var/log/dummy-host.example.com-access_log" common </VirtualHost> The problem is that second rewrite rule doesn't work. Requests slip through to JBoss unchanged, so I get Tomcat 404 error. But if I add redirect flag to the second rule like RewriteRule ^/([^/]+)/([0-9]+)/?$ /$1/view.htm?id=$2 [R,L] it works like a charm. But redirect is not what I need here :) . I suspect that the problem is that requests are forwarded to the another host (192.168.1.2), but I really don't have any idea on how to make it work. Any help would be appreciated :)

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  • help on ejb stateless datagram and message driven beans

    - by Kemmal
    i have a client thats sending a message to the ejbserver using UDP, i want the server(stateless bean) to echo back this message to the client but i cant seem to do this. or can i implement the same logic by using JMS? please help and enlighten. this is just a test, in the end i want a midp to be sending the message to the ejb using datagrams. here is my code. @Stateless public class SessionFacadeBean implements SessionFacadeRemote { public SessionFacadeBean() { } public static void main(String[] args) { DatagramSocket aSocket = null; byte[] buffer = null; try { while(true) { DatagramPacket request = new DatagramPacket(buffer, buffer.length); aSocket.receive(request); DatagramPacket reply = new DatagramPacket(request.getData(), request.getLength(), request.getAddress(), request.getPort()); aSocket.send(reply); } } catch (SocketException e) { System.out.println("Socket: " + e.getMessage()); } catch (IOException e) { System.out.println("IO: " + e.getMessage()); } finally { if(aSocket != null) aSocket.close(); } } } and the client: public static void main(String[] args) { DatagramSocket aSocket = null; try { aSocket = new DatagramSocket(); byte [] m = "Test message!".getBytes(); InetAddress aHost = InetAddress.getByName("localhost"); int serverPort = 6789; DatagramPacket request = new DatagramPacket(m, m.length, aHost, serverPort); aSocket.send(request); byte[] buffer = new byte[1000]; DatagramPacket reply = new DatagramPacket(buffer, buffer.length); aSocket.receive(reply); System.out.println("Reply: " + new String(reply.getData())); } catch (SocketException e) { System.out.println("Socket: " + e.getMessage()); } catch (IOException e) { System.out.println("IO: " + e.getMessage()); } finally { if(aSocket != null) aSocket.close(); } } please help.

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  • PhpBB3: adding background to specific php generated text input without affecting the other text inputs

    - by user1780055
    I have created a custom PhpBB3 style and desperately since a few hours tried to add a background image to a specific comment text area. With firebug I checked if the comment text area had a class and it does, so I tried some css variations and finally tried: sn-inputComment { background: url("{T_THEME_PATH}/images/pencil.png") repeat-x left top #FFFFFF;} { I also tried to find and manipulate the php generated text area but no success. Non of my methods worked. I will provide you all with a tinylink url to my forum with a test user and password access. User: test Password: 123456 url: http://tinyurl.com/9yqpxdb Now when you are logged in you should be redirected to the correct url and you will see a a few text boxes with "Write a comment...". I would be very happy if you could tell me what I did wrong, why im not able to add a background to the text input without having my search boxes and "what is on your mind box" affected. I appreciate your time and hope that this can be somehow solved. Sincerely, Daniel

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  • Insert MANY key value pairs fast into berkeley db with hash access

    - by Kungi
    Hi, i'm trying to build a hash with berkeley db, which shall contain many tuples (approx 18GB of key value pairs), but in all my tests the performance of the insert operations degrades drastically over time. I've written this script to test the performance: #include<iostream> #include<db_cxx.h> #include<ctime> #define MILLION 1000000 int main () { long long a = 0; long long b = 0; int passes = 0; int i = 0; u_int32_t flags = DB_CREATE; Db* dbp = new Db(NULL,0); dbp->set_cachesize( 0, 1024 * 1024 * 1024, 1 ); int ret = dbp->open( NULL, "test.db", NULL, DB_HASH, flags, 0); time_t time1 = time(NULL); while ( passes < 100 ) { while( i < MILLION ) { Dbt key( &a, sizeof(long long) ); Dbt data( &b, sizeof(long long) ); dbp->put( NULL, &key, &data, 0); a++; b++; i++; } DbEnv* dbep = dbp->get_env(); int tmp; dbep->memp_trickle( 50, &tmp ); i=0; passes++; std::cout << "Inserted one million --> pass: " << passes << " took: " << time(NULL) - time1 << "sec" << std::endl; time1 = time(NULL); } } Perhaps you can tell me why after some time the "put" operation takes increasingly longer and maybe how to fix this. Thanks for your help, Andreas

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  • Server 2008 R2 - Boot disk RAID 1 - migrate to larger disk

    - by William Hooper
    My group inherited several 2008 R2 servers with single 70GB RAID 1 boot/system disks. No other disks in the servers. We need larger boot / system disk. Plan is : to replace one disk with new 500 GB drive wait for resync replace other smaller disk with 2nd 500 GB drive wait for resysnc Now I should have 500 GB RAID 1 with original 70 GB partition Then I would like to extend the 70 GB partition to 200 GB and add D: drive partition with remaining 300 GB Can the above be done using Windows Disk Management and / or Windows DiskPart ?

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  • Strategy Pattern with Type Reflection affecting Performances ?

    - by Aurélien Ribon
    Hello ! I am building graphs. A graph consists of nodes linked each other with links (indeed my dear). In order to assign a given behavior to each node, I implemented the strategy pattern. class Node { public BaseNodeBehavior Behavior {get; set;} } As a result, in many parts of the application, I am extensively using type reflection to know which behavior a node is. if (node.Behavior is NodeDataOutputBehavior) workOnOutputNode(node) .... My graph can get thousands of nodes. Is type reflection greatly affecting performances ? Should I use something else than the strategy pattern ? I'm using strategy because I need behavior inheritance. For example, basically, a behavior can be Data or Operator, a Data behavior can IO, Const or Intermediate and finally an IO behavior can be Input or Output. So if I use an enumeration, I wont be able to test for a node behavior to be of data kind, I will need to test it to be [Input, Output, Const or Intermediate]. And if later I want to add another behavior of Data kind, I'm screwed, every data-testing method will need to be changed.

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  • Wake up and record in Windows Media Center on a Mac Mini

    - by Sir Code-A-Lot
    I'm currently considering buying a Mac Mini to use as a media center. I plan to install Windows 7 (or 8) on it, using Boot Camp. Will it be able to go into standby or hibernate (S3, S4?) and wake up to record TV scheduled in Windows Media Center? I haven't been able to find concrete information on supported standby types when running Windows under boot camp, and if Windows will even be able to wake when a recording should start. I just want to be clear on any limitations in this area before I buy anything.

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  • Faster method for Matrix vector product for large matrix in C or C++ for use in GMRES

    - by user35959
    I have a large, dense matrix A, and I aim to find the solution to the linear system Ax=b using an iterative method (in MATLAB was the plan using its built in GMRES). For more than 10,000 rows, this is too much for my computer to store in memory, but I know that the entries in A are constructed by two known vectors x and y of length N and the entries satisfy: A(i,j) = .5*(x[i]-x[j])^2+([y[i]-y[j])^2 * log(x[i]-x[j])^2+([y[i]-y[j]^2). MATLAB's GMRES command accepts as input a function call that can compute the matrix vector product A*x, which allows me to handle larger matrices than I can store in memory. To write the matrix-vecotr product function, I first tried this in matlab by going row by row and using some vectorization, but I avoid spawning the entire array A (since it would be too large). This was fairly slow unfortnately in my application for GMRES. My plan was to write a mex file for MATLAB to, which is in C, and ideally should be significantly faster than the matlab code. I'm rather new to C, so this went rather poorly and my naive attempt at writing the code in C was slower than my partially vectorized attempt in Matlab. #include <math.h> #include "mex.h" void Aproduct(double *x, double *ctrs_x, double *ctrs_y, double *b, mwSize n) { mwSize i; mwSize j; double val; for (i=0; i<n; i++) { for (j=0; j<i; j++) { val = pow(ctrs_x[i]-ctrs_x[j],2)+pow(ctrs_y[i]-ctrs_y[j],2); b[i] = b[i] + .5* val * log(val) * x[j]; } for (j=i+1; j<n; j++) { val = pow(ctrs_x[i]-ctrs_x[j],2)+pow(ctrs_y[i]-ctrs_y[j],2); b[i] = b[i] + .5* val * log(val) * x[j]; } } } The above is the computational portion of the code for the matlab mex file (which is slightly modified C, if I understand correctly). Please note that I skip the case i=j, since in that case the variable val will be a 0*log(0), which should be interpreted as 0 for me, so I just skip it. Is there a more efficient or faster way to write this? When I call this C function via the mex file in matlab, it is quite slow, slower even than the matlab method I used. This surprises me since I suspected that C code should be much faster than matlab. The alternative matlab method which is partially vectorized that I am comparing it with is function Ax = Aprod(x,ctrs) n = length(x); Ax = zeros(n,1); for j=1:(n-3) v = .5*((ctrs(j,1)-ctrs(:,1)).^2+(ctrs(j,2)-ctrs(:,2)).^2).*log((ctrs(j,1)-ctrs(:,1)).^2+(ctrs(j,2)-ctrs(:,2)).^2); v(j)=0; Ax(j) = dot(v,x(1:n-3); end (the n-3 is because there is actually 3 extra components, but they are dealt with separately,so I excluded that code). This is partly vectorized and only needs one for loop, so it makes some sense that it is faster. However, I was hoping I could go even faster with C+mex file. Any suggestions or help would be greatly appreciated! Thanks! EDIT: I should be more clear. I am open to any faster method that can help me use GMRES to invert this matrix that I am interested in, which requires a faster way of doing the matrix vector product without explicitly loading the array into memory. Thanks!

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  • Is the RESTORE process dependent on schema?

    - by Martin Aatmaa
    Let's say I have two database instances: InstanceA - Production server InstanceB - Test server My workflow is to deploy new schema changes to InstanceB first, test them, and then deploy them to InstanceA. So, at any one time, the instance schema relationship looks like this: InstanceA - Schema Version 1.5 InstanceB - Schema Version 1.6 (new version being tested) An additional part of my workflow is to keep the data in InstanceB as fresh as possible. To fulfill this, I am taking the database backups of InstanceA and applying them (restoring them) to InstanceB. My question is, how does schema version affect the restoral process? I know I can do this: Backup InstanceA - Schema Version 1.5 Restore to InstanceB - Schema Version 1.5 But can I do this? Backup InstanceA - Schema Version 1.5 Restore to InstanceB - Schema Version 1.6 (new version being tested) If no, what would the failure look like? If yes, would the type of schema change matter? For example, if Schema Version 1.6 differed from Schema Version 1.5 by just having an altered storec proc, I imagine that this type of schema change should't affect the restoral process. On the other hand, if Schema Version 1.6 differed from Schema Version 1.5 by having a different table definition (say, an additional column), I image this would affect the restoral process. I hope I've made this clear enough. Thanks in advance for any input!

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