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  • How to set up multiple SSIDs with bandwidth limiting on a single wireless router?

    - by Rahul Narain
    I have an Asus WL-520GU wireless router connected to a cable modem that I use for wireless internet access in my apartment. I would like to set it up so that it provides two SSIDs: one secured and password-protected for my regular use, and a "guest" SSID that's unsecured but throttled to, say, 10% of the available bandwidth. What is the most straightforward way to do this? I've been looking into DD-WRT and Tomato, both of which support my router. DD-WRT supports setting up multiple SSIDs using the GUI, but I don't know if it's possible to limit the bandwidth of each SSID independently; point #12 in this FAQ thread says it's not possible to limit by day or by MAC address, which is discouraging but not conclusive. Tomato allows bandwidth limits in its QoS settings, going by the screenshot here, but multiple SSID support is still experimental and it doesn't look like it will work with the encryption settings or bandwidth limits in the GUI. I'd like to know a good way to do this which gives me the fewest opportunities for screwing up. I'm no stranger to the command line, if that turns out to be what's necessary, but if so, please explain what the commands are doing because I don't have a good mental model of what needs to happen to set this up.

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  • Implications of Multiple JobTracker nodes in a Hadoop cluster?

    - by Jim Dennis
    I get the impression that one can, potentially, have multiple JobTracker nodes configured to share the same set of MR (TaskTracker) nodes. I know that, conventionally, all the nodes in a Hadoop cluster should have the same set of configuration files (conventionally under /etc/hadoop/conf/ --- at least for the Cloudera Distribution of Hadoop (CDH). Can we define multiple Job Trackers in mapred-site.xml? Something like: <configuration> <property> <name>mapred.job.tracker</name> <value>jt01.mydomain.not:8021</value> </property> <property> <name>mapred.job.tracker</name> <value>jt02.mydomain.not:8021</value> </property> ... </configuration> Or is there some other allowed syntax for this? What are the implications of doing this. Does each JobTracker get information about the load on each TaskTracker node. In other words can the two JobTracker co-ordinated their scheduling across the TT nodes only based on the gossip information from the TTs or would they need to talk to one another? Is this documented anywhere?

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  • Can mod-rewrite be used to set environmental variables?

    - by VLostBoy
    Hi, I've got an existing simple rewrite rule like so: <Directory /path> RewriteEngine on RewriteBase / # if the requested resource does not exist RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d # route the uri to a front controller RewriteRule ^(.*)$ index.php/$1 [L] </Directory> This works fine, but I want to do one of either two things. On the basis of detecting the clients accept-language header, I want to either (i) Set the detected language as an environmental variable that the script can use or (ii)Rewrite the request so that the url begins with the language code (e.g. www.example.com/en/some/resource) In terms of implementing (i), I defined this rule: <Directory /path> RewriteEngine on RewriteBase / # if the requested resource does not exist RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d # if the users preferred language is supported... RewriteCond %{HTTP:Accept-Language} ^.*(de|es|fr|it|ja|ru|en).*$ [NC] # define an environmental variable PREFER_LANG RewriteRule ^(.*)$ - [env=PREFER_LANG:%1] # route the uri to a front controller RewriteRule ^(.*)$ index.php/$1 [L] </Directory> I've tried a few variations, but PREFER_LANG is not defined in $_SERVER nor retrievable by getenv. In terms of implementing (ii)... lets just say its messy. I'll post it if I can't get an answer to one. Can anyone advise me? Thanks!

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  • Join multiple consecutive SQLite database dump files into 1 common database? Purpose: Search through ENTIRE Chrome Browsing History

    - by porg
    Google Chrome 's default web browsing history search engine only lets you access the records of the recent 100 days. Nevertheless in your application data, Chrome keeps your entire browsing history in SQLite database files, with the file naming scheme of "History Index YYYY-MM". I am looking for a way to search… …through my entire browsing history, …with sophisticated filters (limit search terms to certain fields such as URL, domain, title, body text; wildcard or regex terms, date ranges). … in … …either some ready-made software. eHistory came close, as it can limit terms to fields, but it lacks wildcards/regexes, and has the same limited time horizon as the default search. Beyond that, I could not find any suited Chrome extension or standalone (Mac) app. …or a command line to join multiple SQLite database files into one database, which I can then query (with the full syntax power). In the spirit of the pseudo code below: Preferred this way: sqlite --targetDatabase ChromeHistoryAll --importFiles /path/to/ChromeAppData/History\ Index* --importOnlyYetUnknownFiles Or if my desired feature --importOnlyYetUnknownFiles is not possible (feature could also be called "avoid duplicate imports by checking UIDs"), then by explicitly only importing files, of which I know, that they have yet not been imported into the ChromeHistoryAll database: cd ChromeAppData; sqlite --databaseTarget ChromeHistoryAll --importFiles YetNotImported1 YetNotImported2 YetNotImported3 All my queries I would then perform in the database "ChromeHistoryAll" P.S.: Additional question of general interest: Is there a way to perform a database query in a temporary database which was created on-the-fly from multiple files? Like: sqlite --query="SQL query" --targetDatabase DbAll --DBtemporaryInRAM --importFiles db1 db2 db3 This is surely not applicable for my Chrome question, as these History Index files have a combined file size of 500MB together, thus such a query would be of bad performance. But it could come handy in other situations.

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  • Slicing the EDG

    - by Antony Reynolds
    Different SOA Domain Configurations In this blog entry I would like to introduce three different configurations for a SOA environment.  I have omitted load balancers and OTD/OHS as they introduce a whole new round of discussion.  For each possible deployment architecture I have identified some of the advantages. Super Domain This is a single EDG style domain for everything needed for SOA/OSB.   It extends the standard EDG slightly but otherwise assumes a single “super” domain. This is basically the SOA EDG.  I have broken out JMS servers and Coherence servers to improve scalability and reduce dependencies. Key Points Separate JMS allows those servers to be kept up separately from rest of SOA Domain, allowing JMS clients to post messages even if rest of domain is unavailable. JMS servers are only used to host application specific JMS destinations, SOA/OSB JMS destinations remain in relevant SOA/OSB managed servers. Separate Coherence servers allow OSB cache to be offloaded from OSB servers. Use of Coherence by other components as a shared infrastructure data grid service. Coherence cluster may be managed by WLS but more likely run as a standalone Coherence cluster. Benefits Single Administration Point (1 Admin Server) Closely follows EDG with addition of application specific JMS servers and standalone Coherence servers for OSB caching and application specific caches. Coherence grid can be scaled independent of OSB/SOA. JMS queues provide for inter-application communication. Drawbacks Patching is an all or nothing affair. Startup time for SOA may be slow if large number of composites deployed. Multiple Domains This extends the EDG into multiple domains, allowing separate management and update of these domains.  I see this type of configuration quite often with customers, although some don't have OWSM, others don't have separate Coherence etc. SOA & BAM are kept in the same domain as little benefit is obtained by separating them. Key Points Separate JMS allows those servers to be kept up separately from rest of SOA Domain, allowing JMS clients to post messages even if other domains are unavailable. JMS servers are only used to host application specific JMS destinations, SOA/OSB JMS destinations remain in relevant SOA/OSB managed servers. Separate Coherence servers allow OSB cache to be offloaded from OSB servers. Use of Coherence by other components as a shared infrastructure data grid service. Coherence cluster may be managed by WLS but more likely run as a standalone Coherence cluster. Benefits Follows EDG but in separate domains and with addition of application specific JMS servers and standalone Coherence servers for OSB caching and application specific caches. Coherence grid can be scaled independent of OSB/SOA. JMS queues provide for inter-application communication. Patch lifecycle of OSB/SOA/JMS are no longer lock stepped. JMS may be kept running independently of other domains allowing applications to insert messages fro later consumption by SOA/OSB. OSB may be kept running independent of other domains, allowing service virtualization to continue independent of other domains availability. All domains use same OWSM policy store (MDS-WSM). Drawbacks Multiple domains to manage and configure. Multiple Admin servers (single view requires use of Grid Control) Multiple Admin servers/WSM clusters waste resources. Additional homes needed to enjoy benefits of separate patching. Cross domain trust needs setting up to simplify cross domain interactions. Startup time for SOA may be slow if large number of composites deployed. Shared Service Environment This model extends the previous multiple domain arrangement to provide a true shared service environment.This extends the previous model by allowing multiple additional SOA domains and/or other domains to take advantage of the shared services.  Only one non-shared domain is shown, but there could be multiple, allowing groups of applications to share patching independent of other application groups. Key Points Separate JMS allows those servers to be kept up separately from rest of SOA Domain, allowing JMS clients to post messages even if other domains are unavailable. JMS servers are only used to host application specific JMS destinations, SOA/OSB JMS destinations remain in relevant SOA/OSB managed servers. Separate Coherence servers allow OSB cache to be offloaded from OSB servers. Use of Coherence by other components as a shared infrastructure data grid service Coherence cluster may be managed by WLS but more likely run as a standalone Coherence cluster. Shared SOA Domain hosts Human Workflow Tasks BAM Common "utility" composites Single OSB domain provides "Enterprise Service Bus" All domains use same OWSM policy store (MDS-WSM) Benefits Follows EDG but in separate domains and with addition of application specific JMS servers and standalone Coherence servers for OSB caching and application specific caches. Coherence grid can be scaled independent of OSB/SOA. JMS queues provide for inter-application communication. Patch lifecycle of OSB/SOA/JMS are no longer lock stepped. JMS may be kept running independently of other domains allowing applications to insert messages fro later consumption by SOA/OSB. OSB may be kept running independent of other domains, allowing service virtualization to continue independent of other domains availability. All domains use same OWSM policy store (MDS-WSM). Supports large numbers of deployed composites in multiple domains. Single URL for Human Workflow end users. Single URL for BAM end users. Drawbacks Multiple domains to manage and configure. Multiple Admin servers (single view requires use of Grid Control) Multiple Admin servers/WSM clusters waste resources. Additional homes needed to enjoy benefits of separate patching. Cross domain trust needs setting up to simplify cross domain interactions. Human Workflow needs to be specially configured to point to shared services domain. Summary The alternatives in this blog allow for patching to have different impacts, depending on the model chosen.  Each organization must decide the tradeoffs for itself.  One extreme is to go for the shared services model and have one domain per SOA application.  This requires a lot of administration of the multiple domains.  The other extreme is to have a single super domain.  This makes the entire enterprise susceptible to an outage at the same time due to patching or other domain level changes.  Hopefully this blog will help your organization choose the right model for you.

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  • R ggplot barplot; Fill based on two separate variables

    - by user1476968
    A picture says more than a thousand words. As you can see, my fill is based on the variable variable. Within each bar there is however multiple data entities (black borders) since the discrete variable complexity make them unique. What I am trying to find is something that makes each section of the bar more distinguishable than the current look. Preferable would be if it was something like shading. Here's an example (not the same dataset, since the original was imported): dat <- read.table(text = "Complexity Method Sens Spec MMC 1 L Alpha 50 20 10 2 M Alpha 40 30 80 3 H Alpha 10 10 5 4 L Beta 70 50 60 5 M Beta 49 10 80 6 H Beta 90 17 48 7 L Gamma 19 5 93 8 M Gamma 18 39 4 9 H Gamma 10 84 74", sep = "", header=T) library(ggplot2) library(reshape) short.m <- melt(dat) ggplot(short.m, aes(x=Method, y= value/100 , fill=variable)) + geom_bar(stat="identity",position="dodge", colour="black") + coord_flip()

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  • How to address thread-safety of service data used for maintaining static local variables in C++?

    - by sharptooth
    Consider the following scenario. We have a C++ function with a static local variable: void function() { static int variable = obtain(); //blahblablah } the function needs to be called from multiple threads concurrently, so we add a critical section to avoid concurrent access to the static local: void functionThreadSafe() { CriticalSectionLockClass lock( criticalSection ); static int variable = obtain(); //blahblablah } but will this be enough? I mean there's some magic that makes the variable being initialized no more than once. So there's some service data maintained by the runtime that indicates whether each static local has already been initialized. Will the critical section in the above code protect that service data as well? Is any extra protection required for this scenario?

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  • What is the point declaring variables at the end of class?

    - by serhio
    I saw multiple examples in MSDN that uses to declare the internal fields at the end of the class. What is the point? I find this a little embarrassing, because each time Visual Studio adds a method it adds it to the end of the class, so there is need every time to move it... class A { public A(){} // Methods, Properties, etc ... private string name; } class A { private string name; public A(){} // Methods, Properties, etc ... }

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  • Variables are "lost" somewhere, then reappear... all with no error thrown.

    - by rob - not a robber
    Hi All, I'm probably going to make myself look like a fool with my horrible scripting but here we go. I have a form that I am collecting a bunch of checkbox info from using a binary method. ON/SET=1 !ISSET=0 Anyway, all seems to be going as planned except for the query bit. When I run the script, it runs through and throws no errors, but it's not doing what I think I am telling it to. I've hard coded the values in the query and left them in the script and it DOES update the DB. I've also tried echoing all the needed variables after the script runs and exiting right after so I can audit them... and they're all there. Here's an example. ####FEATURES RECORD UPDATE ### HERE I DECIDE TO RUN THE SCRIPT BASED ON WHETHER AN IMAGE BUTTON WAS USED if (isset($_POST["button_x"])) { ### HERE I AM ASSIGNING 1 OR 0 TO A VAR BASED ON WHTER THE CHECKBOX WAS SET if (isset($_POST["pool"])) $pool=1; if (!isset($_POST["pool"])) $pool=0; if (isset($_POST["darts"])) $darts=1; if (!isset($_POST["darts"])) $darts=0; if (isset($_POST["karaoke"])) $karaoke=1; if (!isset($_POST["karaoke"])) $karaoke=0; if (isset($_POST["trivia"])) $trivia=1; if (!isset($_POST["trivia"])) $trivia=0; if (isset($_POST["wii"])) $wii=1; if (!isset($_POST["wii"])) $wii=0; if (isset($_POST["guitarhero"])) $guitarhero=1; if (!isset($_POST["guitarhero"])) $guitarhero=0; if (isset($_POST["megatouch"])) $megatouch=1; if (!isset($_POST["megatouch"])) $megatouch=0; if (isset($_POST["arcade"])) $arcade=1; if (!isset($_POST["arcade"])) $arcade=0; if (isset($_POST["jukebox"])) $jukebox=1; if (!isset($_POST["jukebox"])) $jukebox=0; if (isset($_POST["dancefloor"])) $dancefloor=1; if (!isset($_POST["dancefloor"])) $dancefloor=0; ### I'VE DONE LOADS OF PERMUTATIONS HERE... HARD SET THE 1/0 VARS AND LEFT THE $estab_id TO BE PICKED UP. SET THE $estab_id AND LEFT THE COLUMN DATA TO BE PICKED UP. ALL NO GOOD. IT _DOES_ WORK IF I HARD SET ALL VARS THOUGH mysql_query("UPDATE thedatabase SET pool_table='$pool', darts='$darts', karoke='$karaoke', trivia='$trivia', wii='$wii', megatouch='$megatouch', guitar_hero='$guitarhero', arcade_games='$arcade', dancefloor='$dancefloor' WHERE establishment_id='22'"); ###WEIRD THING HERE IS IF I ECHO THE VARS AT THIS POINT AND THEN EXIT(); they all show up as intended. header("location:theadminfilething.php"); exit(); THANKS ALL!!!

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  • JNI cached jclass global reference variables being garbage collected?

    - by bubbadoughball
    I'm working in the JNI Invocation API, calling into Java from C. I have some upfront initialization to cache 30+ Java classes into global references. The results of FindClass are passed into NewGlobalRef to acquire a global reference to the class. I'm caching these class variables to reuse them later. I have 30+ global references to classes (and 30+ global methodIDs for the class constructors). In the following sample, I've removed exception handling as well as JNI invocation for the purpose of shortening the code snippet. My working code has exception checks after every JNI call and I'm running with -Xcheck:jni. Here's the snippet: jclass aClass; jclass bClass; jmethodID aCtor; jmethodID bCtor; void getGlobalRef(const char* clazz, jclass* globalClass) { jclass local = (*jenv)->FindClass(jenv,clazz); if (local) { *globalClass = (jclass) (*jenv)->NewGlobalRef(jenv,local); (*jenv)->DeleteLocalRef(jenv,local); } } methodID getMethodID(jclass clazz, const char* method, const char* sig) { return (*jenv)->GetMethodID(jenv,clazz,method,sig); } void initializeJNI() { getGlobalRef("MyProj/Testclass1", &aclass); getGlobalRef("MyProj/Testclass2", &bclass); . . aCtor = getMethodID(aclass,"<init>","()V"); bCtor = getMethodID(bclass,"<init>","(I)V"); } The initializeJNI() function sets the global references for jclasses and method IDs for constructors as well as some jfieldID's and some initialization of C data structures. After initialization, when I call into a JNI function using some of the cached jclasses and ctor jmethodIDs, I get a bad global or local reference calling reported from the -Xcheck:jni. In gdb, I break at the last line of initializeJNI(), and print all jclasses and jmethodIDs and the ones causing problems look to have been turned into garbage or garbage-collected (i.e. 0x00 or 0x06). Is it possible for global references to be gc'ed? Any suggestions?

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  • Should we use temporary variables for the returned values of functions?

    - by totymedli
    I thought about this: Is there a performance difference in these two practices: Store the return value of a function in a temporary variable than give that variable as a parameter to another function. Put the function into the other function. Specification Assuming all classes and functions are written correctly. Case 1. ClassA a = function1(); ClassB b = function2(a); function3(b); Case 2. function3(function2(function1())); I know there aren't a big difference with only one run, but supposed that we could run this a lot of times in a loop, I created some tests. Test #include <iostream> #include <ctime> #include <math.h> using namespace std; int main() { clock_t start = clock(); clock_t ends = clock(); // Case 1. start = clock(); for (int i=0; i<10000000; i++) { double a = cos(1); double b = pow(a, 2); sqrt(b); } ends = clock(); cout << (double) (ends - start) / CLOCKS_PER_SEC << endl; // Case 2. start = clock(); for (int i=0; i<10000000; i++) sqrt(pow(cos(1),2)); ends = clock(); cout << (double) (ends - start) / CLOCKS_PER_SEC << endl; return 0; } Results Case 1 = 6.375 Case 2 = 0.031 Why is the first one is much slower, and if the second one is faster why dont we always write code that way? Anyway does the second pratice has a name? I also wondered what happens if I create the variables outside the for loop in the first case, but the result was the same. Why?

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  • Why do I recieve multiple warnings of "No running instance of xfce4-panel was found" when logging into Xubuntu?

    - by Fredrik
    I'm running Xubuntu 11.04, the bootup-time is quite fast but when I log in it takes close to a minute before the desktop is displayed, meanwhile I see no activity on the hard drive. When I finally have the desktop I see this notification repeated 10 times: and then this one: In .config/autostart I have these entries $ ls xfce4-settings-helper-autostart.desktop xfce4-clipman-plugin-autostart.desktop xfce-panel.desktop $ cat xfce-panel.desktop [Desktop Entry] Encoding=UTF-8 Version=0.9.4 Type=Application Name=xfce4-panel Comment= Exec=xfce4-panel StartupNotify=false Terminal=false Hidden=false I need some assistance to locate the slow startup, which logs to look at etc. And then this annoying message about xfce-panel. Where do I look for from where it is started.

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  • How to fix “Unable to cast COM object of type ‘Microsoft.SharePoint.Library.SPRequestInternalClass’ to interface type ‘Microsoft.SharePoint.Library.ISPRequest” using PowerGUI

    - by ybbest
    I got the error today when debugging some of my PowerShell Script in PowerGUI. The script works perfectly fine in PowerShell console. Then I had spent a couple of hours scratching my head, trying to figure out why. It turns out that the PowerShell Variables Panel causes the problem. Not quite sure why, but collapse the panel fix the problem. Problem: It throws the following exception when debugging my PowerShell Script. Analysis: It turns out that the PowerShell Variables Panel causes the problem. I assume it calls some function to grab value of some of variables which cause the problems. Solution: Collapse or Close the variables panel fix the problem

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  • JavaScript Intellisense Improvements with VS 2010

    - by ScottGu
    This is the twentieth in a series of blog posts I’m doing on the upcoming VS 2010 and .NET 4 release.  Today’s blog post covers some of the nice improvements coming with JavaScript intellisense with VS 2010 and the free Visual Web Developer 2010 Express.  You’ll find with VS 2010 that JavaScript Intellisense loads much faster for large script files and with large libraries, and that it now provides statement completion support for more advanced scenarios compared to previous versions of Visual Studio. [In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu] Improved JavaScript Intellisense Providing Intellisense for a dynamic language like JavaScript is more involved than doing so with a statically typed language like VB or C#.  Correctly inferring the shape and structure of variables, methods, etc is pretty much impossible without pseudo-executing the actual code itself – since JavaScript as a language is flexible enough to dynamically modify and morph these things at runtime.  VS 2010’s JavaScript code editor now has the smarts to perform this type of pseudo-code execution as you type – which is how its intellisense completion is kept accurate and complete.  Below is a simple walkthrough that shows off how rich and flexible it is with the final release. Scenario 1: Basic Type Inference When you declare a variable in JavaScript you do not have to declare its type.  Instead, the type of the variable is based on the value assigned to it.  Because VS 2010 pseudo-executes the code within the editor, it can dynamically infer the type of a variable, and provide the appropriate code intellisense based on the value assigned to a variable. For example, notice below how VS 2010 provides statement completion for a string (because we assigned a string to the “foo” variable): If we later assign a numeric value to “foo” the statement completion (after this assignment) automatically changes to provide intellisense for a number: Scenario 2: Intellisense When Manipulating Browser Objects It is pretty common with JavaScript to manipulate the DOM of a page, as well as work against browser objects available on the client.  Previous versions of Visual Studio would provide JavaScript statement completion against the standard browser objects – but didn’t provide much help with more advanced scenarios (like creating dynamic variables and methods).  VS 2010’s pseudo-execution of code within the editor now allows us to provide rich intellisense for a much broader set of scenarios. For example, below we are using the browser’s window object to create a global variable named “bar”.  Notice how we can now get intellisense (with correct type inference for a string) with VS 2010 when we later try and use it: When we assign the “bar” variable as a number (instead of as a string) the VS 2010 intellisense engine correctly infers its type and modifies statement completion appropriately to be that of a number instead: Scenario 3: Showing Off Because VS 2010 is psudo-executing code within the editor, it is able to handle a bunch of scenarios (both practical and wacky) that you throw at it – and is still able to provide accurate type inference and intellisense. For example, below we are using a for-loop and the browser’s window object to dynamically create and name multiple dynamic variables (bar1, bar2, bar3…bar9).  Notice how the editor’s intellisense engine identifies and provides statement completion for them: Because variables added via the browser’s window object are also global variables – they also now show up in the global variable intellisense drop-down as well: Better yet – type inference is still fully supported.  So if we assign a string to a dynamically named variable we will get type inference for a string.  If we assign a number we’ll get type inference for a number.  Just for fun (and to show off!) we could adjust our for-loop to assign a string for even numbered variables (bar2, bar4, bar6, etc) and assign a number for odd numbered variables (bar1, bar3, bar5, etc): Notice above how we get statement completion for a string for the “bar2” variable.  Notice below how for “bar1” we get statement completion for a number:   This isn’t just a cool pet trick While the above example is a bit contrived, the approach of dynamically creating variables, methods and event handlers on the fly is pretty common with many Javascript libraries.  Many of the more popular libraries use these techniques to keep the size of script library downloads as small as possible.  VS 2010’s support for parsing and pseudo-executing libraries that use these techniques ensures that you get better code Intellisense out of the box when programming against them. Summary Visual Studio 2010 (and the free Visual Web Developer 2010 Express) now provide much richer JavaScript intellisense support.  This support works with pretty much all popular JavaScript libraries.  It should help provide a much better development experience when coding client-side JavaScript and enabling AJAX scenarios within your ASP.NET applications. Hope this helps, Scott P.S. You can read my previous blog post on VS 2008’s JavaScript Intellisense to learn more about our previous JavaScript intellisense (and some of the scenarios it supported).  VS 2010 obviously supports all of the scenarios previously enabled with VS 2008.

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  • A temporary disagreement

    - by Tony Davis
    Last month, Phil Factor caused a furore amongst some MVPs with an article that attempted to offer simple advice to developers regarding the use of table variables, versus local and global temporary tables, in their code. Phil makes clear that the table variables do come with some fairly major limitations.no distribution statistics, no parallel query plans for queries that modify table variables.but goes on to suggest that for reasonably small-scale strategic uses, and with a bit of due care and testing, table variables are a "good thing". Not everyone shares his opinion; in fact, I imagine he was rather aghast to learn that there were those felt his article was akin to pulling the pin out of a grenade and tossing it into the database; table variables should be avoided in almost all cases, according to their advice, in favour of temp tables. In other words, a fairly major feature of SQL Server should be more-or-less 'off limits' to developers. The problem with temp tables is that, because they are scoped either in the procedure or the connection, it is easy to allow them to hang around for too long, eating up precious memory and bulking up the shared tempdb database. Unless they are explicitly dropped, global temporary tables, and local temporary tables created within a connection rather than within a stored procedure, will persist until the connection is closed or, with connection pooling, until the connection is reused. It's also quite common with ASP.NET applications to have connection leaks, as Bill Vaughn explains in his chapter in the "SQL Server Deep Dives" book, meaning that the web page exits without closing the connection object, maybe due to an error condition. This will then hang around in the heap for what might be hours before picked up by the garbage collector. Table variables are much safer in this regard, since they are batch-scoped and so are cleaned up automatically once the batch is complete, which also means that they are intuitive to use for the developer because they conform to scoping rules that are closer to those in procedural code. On the surface then, an ideal way to deal with issues related to tempdb memory hogging. So why did Phil qualify his recommendation to use Table Variables? This is another of those cases where, like scalar UDFs and table-valued multi-statement UDFs, developers can sometimes get into trouble with a relatively benign-looking feature, due to way it's been implemented in SQL Server. Once again the biggest problem is how they are handled internally, by the SQL Server query optimizer, which can make very poor choices for JOIN orders and so on, in the absence of statistics, especially when joining to tables with highly-skewed data. The resulting execution plans can be horrible, as will be the resulting performance. If the JOIN is to a large table, that will hurt. Ideally, Microsoft would simply fix this issue so that developers can't get burned in this way; they've been around since SQL Server 2000, so Microsoft has had a bit of time to get it right. As I commented in regard to UDFs, when developers discover issues like with such standard features, the database becomes an alien planet to them, where death lurks around each corner, and they continue to avoid these "killer" features years after the problems have been eventually resolved. In the meantime, what is the right approach? Is it to say "hammers can kill, don't ever use hammers", or is it to try to explain, as Phil's article and follow-up blog post have tried to do, what the feature was intended for, why care must be applied in its use, and so enable developers to make properly-informed decisions, without requiring them to delve deep into the inner workings of SQL Server? Cheers, Tony.

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  • Analiytics: Can I set a goal on multiple events?

    - by David Parks
    We have a popup dialogue that requests users email address or facebook login. The page behind the popup loads, so a page view is counted. We want to measure: How many users ignored the popup completely How many users engaged the popup, but don't complete the process (we trigger an event when the user performs actions defined as "engaging") How many users completed the popup Bounce rates aren't telling because some users won't receive the popup. We are basically triggering events "PopupDisplayed" "PopupEngaged" and "PopupComplete", with labels to differentiate between email and facebook. But I don't think I can set goals to count "Users who received 'PopupDisplayed' AND 'PopupComplete'" events, so I can count how many users both saw the popup and completed it.

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  • Should I use the same AddThis tag on multiple sites?

    - by ripper234
    I have an AddThis for one site: <script type="text/javascript" src="http://s7.addthis.com/js/250/addthis_widget.js#pubid=ripper234"> </script> Now I logged into AddThis and wanted to get my tag again, I saw it changed: <script type="text/javascript" src="http://s7.addthis.com/js/300/addthis_widget.js#pubid=ripper234"> </script> Should I use the same tag I got before, or the new tag? What's the difference? Is 250/300 the internal version number?

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  • Ubuntu One Sync for multiple folders, not just the Ubuntu One folder.

    - by bisi
    Hello, I may have misunderstood Ubuntu One as a service, but this is how I had pictured it. At home, I tagged a few folders with the "Sync to Ubuntu One" tick and it started uploading. Now back at work, on Win7, I installed Ubuntu One and thought I was going to be able to tick which of the backed-up folders I could download/sync to this machine. From what I gather after a little research is that whatever I would like to synchronize would need to be in the Ubuntu One folder? There is no way to do this outside of that? Thanks for confirming, or informing me whether this will be introduced in the future as an option? Thank you very much for your help on this! bisi

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  • How should I log time spent on multiple tasks?

    - by xenoterracide
    In Joel's blog on evidence based scheduling he suggests making estimates based on the smallest unit of work and logging extra work back to the original task. The problem I'm now experiencing is that I'll have create object A with subtask method A which creates object B and test all of the above. I create tasks for each of these that seems to be resulting in ok-ish estimates (need practice), but when I go to log work I find that I worked on 4 tasks at once because I tweak method A and find a bug in the test and refactor object B all while coding it. How should I go about logging this work? should I say I spent, for example, 2 hours on each of the 4 tasks I worked on in the 8 hour day?

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  • Is there a pattern or best practice for passing a reference type to multiple classes vs a static class?

    - by Dave
    My .NET application creates HTML files, and as such, the structure looks like variable myData BuildHomePage() variable graph = new BuildGraphPage(myData) variable table = BuildTablePage(myData) BuildGraphPage and BuildTablePage both require access data, the myData object. In the above example, I've passed the myData object to 2 constructors. This is what I'm doing now, in my current project. The myData object, and it's properties are all readonly. The problem is, the number of pages which will require this object has grown. In the real project, there are currently 4, but the new spec is to have about 20. Passing this object to the constructor of each new object and assigning it to a field is a little time consuming, but not a hardship! This poses the question whether it's better practice to continue as I have, or to refactor and create a new static class for myData which can be referenced from any where in my project. I guess my abilities to use Google are poor, because I did try and find an appropriate pattern as I am sure this type of design must be common place but my results returned nothing. Is there a pattern which is suited, or do best practices lean towards one implementation over another.

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  • To have multiple sites with similar content on the same server but different IPs?

    - by Eugene
    I have 7 different sites on the same dedicated server. Two major sites have different IPs, and 5 small share the same IP. About first 2 they have similar content, but not the same. Basically they have different: URLs Titles Meta Data But they both have the same niche. I was thinking about two strategies. One is to move one of the sites (from 2 first one) on different server or move 5 other sites on different server. But I'm not sure which way is better. My questions are: Wouldn't be better from SEO stand point, to move those 2 sites on different servers? Does it worth it to spend for additional server? Do you know if Google penalize sites for similar content on the same server with different IPs?

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  • Is there a Content Management System that allows multiple & independent blogs to be running on one domain?

    - by Ron
    Hello Webmasters, I am a Wordpress fan, and I'm now building a new site and I'm not sure which CMS can achieve what I'm trying to do. I am building a food blog network for a bunch of cities in the US, and I want to my city pages to be independently running blogs themselves. So basically... Home Page - Its own blog with its own users, talking about Food in general Dallas Page (child of home page) - Its own blog with its own users Chicago Page ..... so on and so forth. The web layout and design will be all the same, but just trying to achieve 25~50 independent blogs on one domain. How can I achieve this? I'm hoping that I don't have to install Wordpress into as many subdomains that I create... Thank you for your help in advance. -RP

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  • Why do people have to use multiple versions of jQuery in the same page?

    - by reprogrammer
    I have noticed that sometimes people have to use multiple versions of jQuery in the same page (See question 1 and question 2). I assume people have to carry old versions of jQuery because some pieces of their code is based on an older version of jQuery. Obviously, this approach causes inefficiency. The ideal solution is to refactor the old code to use the newer jQuery API. I wonder if there are tools that automate the process of upgrading a piece of code to use a newer version of jQuery. I've never written programs in in either Javascript or jQuery. So, I'd like to hear from programmers experienced in these language about their opinion on this issue. In particular, I'd like to know the following. How much of problem it is to have to load multiple versions of jQuery? Have you ever had to load multiple versions of any other library in the same page? Do you know of any refactoring tools that helps you migrate your code to use the updated API? Do you think such a refactoring tool is useful? Are you willing to use it?

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  • Business operates in multiple counties, will adding a listing in the Local Business sites harm our placement in SERPs?

    - by leeand00
    I work at a non-profit where we operate in more than two counties within our state. Our offices are located in two different towns, and that leaves a few counties of operation where we would also like to appear in their local SERPs or Local Business listings. Please note that these towns are not necessarily close to all the areas of operation. Since we don't have offices in all the counties of operation, how can we effectively post our business in the Local Business Listings and still show up in our counties of operation?

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  • How do I detect multiple sprite collisions when there are >10 sprites?

    - by yao jiang
    I making a small program to animate the astar algorithm. If you look at the image, there are lots of yellow cars moving around. Those can collide at any moment, could be just one or all of them could just stupidly crash into each other. How do I detect all of those collisions? How do I find out which specific car has crash into which other car? I understand that pygame has collision function, but it only detects one collision at a time and I'd have to specify which sprites. Right now I am just trying to iterate through each sprite to see if there is collision: for car1 in carlist: for car2 in carlist: collide(car1, car2); This can't be the proper way to do it, if the car list goes to a huge number, a double loop will be too slow.

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