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  • How do you fix the Performance Dashboard datetime overfow error

    - by Mike L
    I'm a programmer/DBA by accident and we're running SQL Server 2005 with Performance Dashboard for basic monitoring. The server has been up for a few weeks and now we can't drill into certain reports. Is there any way to reset these reports without a complete reboot? edit: I bet the error message would help. I get this when I drill into the CPU graph: Error: Difference of two datetime columns caused overflow at runtime.

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  • How to change default boot order ubuntu 10.04 ?

    - by Sako Christian
    Hello, How can I change default boot order in Ubuntu 10.04 from Ubuntu to Windows7? However, I already checked sudo gedit /etc/default/grub and modify the grub file to be GRUB_DEFAULT=4 and update the grup sudo update-grub I even install graph software to re order the book sudo startupmanager But still after restart the default choose for boot is Ubuntu ... Thank you, Sako Christian P.S: I am using Ubuntu 10.04 with grub version 1.98

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  • Sysinternal's Process Explorer v14 doesn't show network activity.

    - by MikMik
    The new version of Process Explorer shows network activity history, but it doesn't in one of my computers. This particular PC runs Windows XP SP3 and it has just been reformatted so everything is "fresh". I have even installed WinPCap and Microsoft Network monitor, in case some of these drivers were necessary, but the graph stays in 0. Any ideas why this could happen? I would ask in Sysinternal's forum, but I really don't want to register in yet another forum.

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  • Unusually high memory usage on a CentOS VPS with 512 guaranteed RAM

    - by Andrei Bârsan
    I'm working on a medium-sized web application written in PHP that's running on a VPS with 512mb ram. The webapp hasn't been officially launched yet, so there isn't too much traffic going on, just me and a few other people working on it. There is another slightly smaller webapp also hosted on this machine, among 4-5 other small static sites. We are running Centos 5 32-bit & cPanel/WHM. This is the result of running ps aux and, as you can see, it's not using 100% of the RAM. However, on the hypanel overview, it's always shown as using aroun 500MB ram, just for running apache, mysql, and the lowest-memory-footprint versions of the mail server, ftp server etc. -bash-3.2# ps aux USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 1 0.0 0.0 2156 664 ? Ss 12:08 0:00 init [3] root 1123 0.0 0.0 2260 548 ? S<s 12:08 0:00 /sbin/udevd -d root 1462 0.0 0.0 1812 568 ? Ss 12:08 0:00 syslogd -m 0 named 1496 0.0 0.0 3808 820 ? Ss 12:08 0:00 nsd named 1497 0.0 0.0 10672 756 ? S 12:08 0:00 nsd named 1499 0.0 0.0 3880 584 ? S 12:08 0:00 nsd root 1514 0.0 0.1 7240 1064 ? Ss 12:08 0:00 /usr/sbin/sshd root 1522 0.0 0.0 2832 832 ? Ss 12:08 0:00 xinetd -stayalive -pidfile /var/run/xinetd.pid root 1534 0.0 0.1 3712 1328 ? S 12:08 0:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql - mysql 1667 0.0 2.9 225680 30884 ? Sl 12:08 0:00 /usr/sbin/mysqld --basedir=/ --datadir=/var/lib/mysql - mailnull 1766 0.0 0.1 9352 1100 ? Ss 12:08 0:00 /usr/sbin/exim -bd -q60m root 1797 0.0 0.0 2156 708 ? Ss 12:08 0:00 /usr/sbin/dovecot root 1798 0.0 0.0 2632 1012 ? S 12:08 0:00 dovecot-auth root 1816 0.0 3.0 38580 32456 ? Ss 12:08 0:01 /usr/local/bin/spamd -d --allowed-ips=127.0.0.1 --pidfi root 1839 0.0 1.6 63200 17496 ? Ss 12:08 0:00 /usr/local/apache/bin/httpd -k start -DSSL root 1846 0.0 0.1 5416 1468 ? Ss 12:08 0:00 pure-ftpd (SERVER) root 1848 0.0 0.1 6212 1244 ? S 12:08 0:00 /usr/sbin/pure-authd -s /var/run/ftpd.sock -r /usr/sbin root 1856 0.0 0.1 4492 1112 ? Ss 12:08 0:00 crond root 1864 0.0 0.0 2356 428 ? Ss 12:08 0:00 /usr/sbin/atd dovecot 1927 0.0 0.1 5196 1952 ? S 12:08 0:00 pop3-login dovecot 1928 0.0 0.1 5196 1948 ? S 12:08 0:00 pop3-login dovecot 1929 0.0 0.1 5316 2012 ? S 12:08 0:00 imap-login dovecot 1930 0.0 0.2 5416 2228 ? S 12:08 0:00 imap-login root 1939 0.0 0.1 3936 1964 ? S 12:08 0:00 cPhulkd - processor root 1963 0.0 0.8 15876 8564 ? S 12:08 0:00 cpsrvd (SSL) - waiting for connections root 1966 0.0 0.7 15172 7748 ? S 12:08 0:00 cpdavd - accepting connections on 2077 and 2078 root 1990 0.0 0.2 5008 3136 ? S 12:08 0:00 queueprocd - wait to process a task root 2017 0.0 2.9 38580 31020 ? S 12:08 0:00 spamd child root 2018 0.0 0.5 8904 5636 ? S 12:08 0:00 /usr/bin/perl /usr/local/cpanel/bin/leechprotect nobody 2021 0.0 3.2 66512 33724 ? S 12:08 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 2022 0.0 3.1 67812 33024 ? S 12:08 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 2024 0.0 1.9 64364 20680 ? S 12:08 0:00 /usr/local/apache/bin/httpd -k start -DSSL root 2027 0.0 0.4 9000 4540 ? S 12:08 0:00 tailwatchd root 2032 0.0 0.1 4176 1836 ? SN 12:08 0:00 cpanellogd - sleeping for logs nobody 3096 0.0 1.9 64572 20264 ? S 12:09 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 3097 0.0 2.8 66008 30136 ? S 12:09 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 3098 0.0 2.8 65704 29752 ? S 12:09 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 3099 0.0 3.1 67260 32816 ? S 12:09 0:00 /usr/local/apache/bin/httpd -k start -DSSL andrei 3448 0.0 0.1 3204 1632 ? S 12:50 0:00 imap nobody 3537 0.0 1.9 64308 20108 ? S 13:01 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 3614 0.0 1.9 64576 20628 ? S 13:10 0:00 /usr/local/apache/bin/httpd -k start -DSSL nobody 3615 0.0 1.3 63200 14672 ? S 13:10 0:00 /usr/local/apache/bin/httpd -k start -DSSL root 3626 0.0 0.2 10232 2964 ? Rs 13:14 0:00 sshd: root@pts/0 root 3648 0.0 0.1 3844 1600 pts/0 Ss 13:14 0:00 -bash root 3826 0.0 0.0 2532 908 pts/0 R+ 13:21 0:00 ps aux Lately, without any significant changes to the configuration, the memory usage started peaking and going over 512, causing the virtual server to kill apache, basically murdering our site in the process. Do you have any idea if this is normal and more resources should be acquired? I don't think... since there isn't too much data or traffic online yet.

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  • Bash-Scripting - Munin Plugin don't work

    - by FTV Admin
    i have written a munin-plugin to count the http-statuscodes of lighttpd. The script: #!/bin/bash ###################################### # Munin-Script: Lighttpd-Statuscodes # ###################################### ##Config # path to lighttpd access.log LIGHTTPD_ACCESS_LOG_PATH="/var/log/lighttpd/access.log" # rows to parse in logfile (higher value incrase time to run plugin. if value to low you may get bad counting) LOG_ROWS="200000" # #munin case $1 in autoconf) # check config AVAILABLE=`ls $LIGHTTPD_ACCESS_LOG_PATH` if [ "$AVAILABLE" = "$LIGHTTPD_ACCESS_LOG_PATH" ]; then echo "yes" else echo "No: "$AVAILABLE echo "Please check your config!" fi exit 0;; config) # graph config cat <<'EOM' graph_title Lighhtpd Statuscodes graph_vlabel http-statuscodes / min graph_category lighttpd 1xx.label 1xx 2xx.label 2xx 3xx.label 3xx 4xx.label 4xx 5xx.label 5xx EOM exit 0;; esac ## calculate AVAILABLE=`ls $LIGHTTPD_ACCESS_LOG_PATH` if [ "$AVAILABLE" = "$LIGHTTPD_ACCESS_LOG_PATH" ]; then TIME_NOW=`date` CODE_1xx="0" CODE_2xx="0" CODE_3xx="0" CODE_4xx="0" CODE_5xx="0" for i in 1 2 3 4 5; do TIME5=`date +%d/%b/%Y:%k:%M --date "$TIME_NOW -"$i"min"` CODE_1xx=$(( $CODE_1xx + `tail -n $LOG_ROWS $LIGHTTPD_ACCESS_LOG_PATH | grep "$TIME5" | grep 'HTTP/1.1" 1' | grep -c " "` )) CODE_2xx=$(( $CODE_2xx + `tail -n $LOG_ROWS $LIGHTTPD_ACCESS_LOG_PATH | grep "$TIME5" | grep 'HTTP/1.1" 2' | grep -c " "` )) CODE_3xx=$(( $CODE_3xx + `tail -n $LOG_ROWS $LIGHTTPD_ACCESS_LOG_PATH | grep "$TIME5" | grep 'HTTP/1.1" 3' | grep -c " "` )) CODE_4xx=$(( $CODE_4xx + `tail -n $LOG_ROWS $LIGHTTPD_ACCESS_LOG_PATH | grep "$TIME5" | grep 'HTTP/1.1" 4' | grep -c " "` )) CODE_5xx=$(( $CODE_5xx + `tail -n $LOG_ROWS $LIGHTTPD_ACCESS_LOG_PATH | grep "$TIME5" | grep 'HTTP/1.1" 5' | grep -c " "` )) done CODE_1xx=$(( $CODE_1xx / 5 )) CODE_2xx=$(( $CODE_2xx / 5 )) CODE_3xx=$(( $CODE_3xx / 5 )) CODE_4xx=$(( $CODE_4xx / 5 )) CODE_5xx=$(( $CODE_5xx / 5 )) echo "1xx.value "$CODE_1xx echo "2xx.value "$CODE_2xx echo "3xx.value "$CODE_3xx echo "4xx.value "$CODE_4xx echo "5xx.value "$CODE_5xx else echo "1xx.value U" echo "2xx.value U" echo "3xx.value U" echo "4xx.value U" echo "5xx.value U" fi If i run the script on local machine it runs perfectly: root@server1 /etc/munin/plugins # ll lrwxrwxrwx 1 root root 45 2011-12-19 15:23 lighttpd_statuscodes -> /usr/share/munin/plugins/lighttpd_statuscodes* root@server1 /etc/munin/plugins # ./lighttpd_statuscodes autoconf yes root@server1 /etc/munin/plugins # ./lighttpd_statuscodes config graph_title Lighhtpd Statuscodes graph_vlabel http-statuscodes / min graph_category lighttpd 1xx.label 1xx 2xx.label 2xx 3xx.label 3xx 4xx.label 4xx 5xx.label 5xx root@server1 /etc/munin/plugins #./lighttpd_statuscodes 1xx.value 0 2xx.value 5834 3xx.value 1892 4xx.value 0 5xx.value 0 But Munin shows no graph: http://s1.directupload.net/images/111219/3psgq3vb.jpg I have tested the Plugin from munin-server via telnet: root@munin-server /etc/munin/plugins/ # telnet 123.123.123.123 4949 Trying 123.123.123.123... Connected to 123.123.123.123. Escape character is '^]'. # munin node at server1.cluster1 fetch lighttpd_statuscodes 1xx.value U 2xx.value U 3xx.value U 4xx.value U 5xx.value U . Connection closed by foreign host. You can see in the script that value = U only printed, when the script can't check the lighttpd's access.log. But why can't script do it, when running via munin, and when running on local machine all is ok? Is there a bug in my bash-script? I have no Idea. Thanks for helping!

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  • Getting more from an electricity monitor

    - by beakersoft
    Hi, I've recently got a free smart power electric energy monitor from my electric provider (npower, in the UK). While it is quite good i would like to pull the information from the monitor onto my home server, so i can get more detailed information and maybe graph it using mrtg or similar. Has anyone every tinkered about with them, how do the monitor and the display talk to each other (bluetooth/wifi) and any other info people might have. cheers Luke

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  • openvz graphing user_beancounters

    - by Jona
    Hi there, We run a cluster of openvz servers and are looking for a way to automatically graph the content of user_beancounters for all ves. We currently have a fairly rudimentary cron which alerts us when limits are hit but we could like a graphing solution to show us history. Obviously we could roll our own using some fancy bash/php/perl and rrdtool but we're wondering if there are any existing solutions before we go down this path. We current run a cacti/snmp based graphing infrastructure.

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  • Sysinternal's Process Explorer v14 doesn't show network activity

    - by MikMik
    The new version of Process Explorer shows network activity history, but it doesn't in one of my computers. This particular PC runs Windows XP SP3 and it has just been reformatted so everything is "fresh". I have even installed WinPCap and Microsoft Network monitor, in case some of these drivers were necessary, but the graph stays in 0. Any ideas why this could happen? I would ask in Sysinternal's forum, but I really don't want to register in yet another forum.

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  • What is the best way to solve an Objective-C namespace collision?

    - by Mecki
    Objective-C has no namespaces; it's much like C, everything is within one global namespace. Common practice is to prefix classes with initials, e.g. if you are working at IBM, you could prefix them with "IBM"; if you work for Microsoft, you could use "MS"; and so on. Sometimes the initials refer to the project, e.g. Adium prefixes classes with "AI" (as there is no company behind it of that you could take the initials). Apple prefixes classes with NS and says this prefix is reserved for Apple only. So far so well. But appending 2 to 4 letters to a class name in front is a very, very limited namespace. E.g. MS or AI could have an entirely different meanings (AI could be Artificial Intelligence for example) and some other developer might decide to use them and create an equally named class. Bang, namespace collision. Okay, if this is a collision between one of your own classes and one of an external framework you are using, you can easily change the naming of your class, no big deal. But what if you use two external frameworks, both frameworks that you don't have the source to and that you can't change? Your application links with both of them and you get name conflicts. How would you go about solving these? What is the best way to work around them in such a way that you can still use both classes? In C you can work around these by not linking directly to the library, instead you load the library at runtime, using dlopen(), then find the symbol you are looking for using dlsym() and assign it to a global symbol (that you can name any way you like) and then access it through this global symbol. E.g. if you have a conflict because some C library has a function named open(), you could define a variable named myOpen and have it point to the open() function of the library, thus when you want to use the system open(), you just use open() and when you want to use the other one, you access it via the myOpen identifier. Is something similar possible in Objective-C and if not, is there any other clever, tricky solution you can use resolve namespace conflicts? Any ideas? Update: Just to clarify this: answers that suggest how to avoid namespace collisions in advance or how to create a better namespace are certainly welcome; however, I will not accept them as the answer since they don't solve my problem. I have two libraries and their class names collide. I can't change them; I don't have the source of either one. The collision is already there and tips on how it could have been avoided in advance won't help anymore. I can forward them to the developers of these frameworks and hope they choose a better namespace in the future, but for the time being I'm searching a solution to work with the frameworks right now within a single application. Any solutions to make this possible?

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  • Zenoss need to get freespace threshold and alerts on windows "mount points"

    - by agilenoob
    I have a WMI query that will give me all the data I need to do this but I can't figure out how to get this working in Zenoss. I know I need to set data points and a threshold, and optionaly a graph. The problem is examples of how to do this with WMI are few and very confusing. Could anyone atleast point me to documention on how to do this? WMI Query(WQL): "SELECT Caption, Capacity, Freespace FROM Win32_Volume WHERE DriveLetter IS NULL"

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  • Software to report internet traffic for home user

    - by Mehper C. Palavuzlar
    I need a freeware to monitor my internet activity, especially upload and download amounts over time. For instance, I like to see a graph or table that shows the downloaded and uploaded amounts per day, week or month and in total for a selected period. OS: Windows XP, Vista, 7 Edit: I don't need to see the traffic program by program. I'm not interested in which program accesses the internet, but I'm interested in monitoring my incoming and outgoing data amounts using a light-weight freeware.

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  • How do I make the first row of an Excel chart be treated as a heading when it's a number?

    - by Andrew Grimm
    Given a data sample like Prisoner 24601 0.50 Day 1 80 90 Day 2 81 89 Day 3 82 90 Day 4 81 91 What's the easiest way to tell Excel that 24601 and 0.50 are data series names rather than Y axis values when creating a line chart? Approaches I'm aware of: Turn Prisoner numbers into text by having ="24601" and ="0.50" Only select rows 2 onwards as data, and then add in the labels once the graph has been created? Approaches that don't appear to work: Ask Excel to format the first row's numbers as text.

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  • Matplotlib plotting non uniform data in 3D surface

    - by Raj Tendulkar
    I have a simple code to plot the points in 3D for Matplotlib as below - from mpl_toolkits.mplot3d import axes3d import matplotlib.pyplot as plt import numpy as np from numpy import genfromtxt import csv fig = plt.figure() ax = fig.add_subplot(111, projection='3d') my_data = genfromtxt('points1.csv', delimiter=',') points1X = my_data[:,0] points1Y = my_data[:,1] points1Z = my_data[:,2] ## I remove the header of the CSV File. points1X = np.delete(points1X, 0) points1Y = np.delete(points1Y, 0) points1Z = np.delete(points1Z, 0) # Convert the array to 1D array points1X = np.reshape(points1X,points1X.size) points1Y = np.reshape(points1Y,points1Y.size) points1Z = np.reshape(points1Z,points1Z.size) my_data = genfromtxt('points2.csv', delimiter=',') points2X = my_data[:,0] points2Y = my_data[:,1] points2Z = my_data[:,2] ## I remove the header of the CSV File. points2X = np.delete(points2X, 0) points2Y = np.delete(points2Y, 0) points2Z = np.delete(points2Z, 0) # Convert the array to 1D array points2X = np.reshape(points2X,points2X.size) points2Y = np.reshape(points2Y,points2Y.size) points2Z = np.reshape(points2Z,points2Z.size) ax.plot(points1X, points1Y, points1Z, 'd', markersize=8, markerfacecolor='red', label='points1') ax.plot(points2X, points2Y, points2Z, 'd', markersize=8, markerfacecolor='blue', label='points2') plt.show() My problem is that I tried to make a decent surface plot out of these data points that I have. I already tried to use ax.plot_surface() function to make it look nice. For this I eliminated some points, and recalculated the matrix kind of input needed by this function. However, the graph I generated was far more difficult to interpret and understand. So there might be 2 possibilities: either I am not using the function correctly, or otherwise, the data I am trying to plot is not good for the surface plot. What I was expecting was 3D graph which would have an effect similar to that we have of 3D pie chart. We see that one piece (that which is extracted out) is part of another piece. I was not expecting it to be exactly same like that, but some kind of effect like that. What I would like to ask is: Do you think it will be possible to make such 3D graph? Is there any way better, I could express my data in 3 dimension? Here are the 2 files - points1.csv Dim1,Dim2,Dim3 3,8,1 3,8,2 3,8,3 3,8,4 3,8,5 3,9,1 3,9,2 3,9,3 3,9,4 3,9,5 3,10,1 3,10,2 3,10,3 3,10,4 3,10,5 3,11,1 3,11,2 3,11,3 3,11,4 3,11,5 3,12,1 3,12,2 3,13,1 3,13,2 3,14,1 3,14,2 3,15,1 3,15,2 3,16,1 3,16,2 3,17,1 3,17,2 3,18,1 3,18,2 4,8,1 4,8,2 4,8,3 4,8,4 4,8,5 4,9,1 4,9,2 4,9,3 4,9,4 4,9,5 4,10,1 4,10,2 4,10,3 4,10,4 4,10,5 4,11,1 4,11,2 4,11,3 4,11,4 4,11,5 4,12,1 4,13,1 4,14,1 4,15,1 4,16,1 4,17,1 4,18,1 5,8,1 5,8,2 5,8,3 5,8,4 5,8,5 5,9,1 5,9,2 5,9,3 5,9,4 5,9,5 5,10,1 5,10,2 5,10,3 5,10,4 5,10,5 5,11,1 5,11,2 5,11,3 5,11,4 5,11,5 5,12,1 5,13,1 5,14,1 5,15,1 5,16,1 5,17,1 5,18,1 6,8,1 6,8,2 6,8,3 6,8,4 6,8,5 6,9,1 6,9,2 6,9,3 6,9,4 6,9,5 6,10,1 6,11,1 6,12,1 6,13,1 6,14,1 6,15,1 6,16,1 6,17,1 6,18,1 7,8,1 7,8,2 7,8,3 7,8,4 7,8,5 7,9,1 7,9,2 7,9,3 7,9,4 7,9,5 and points2.csv Dim1,Dim2,Dim3 3,12,3 3,12,4 3,12,5 3,13,3 3,13,4 3,13,5 3,14,3 3,14,4 3,14,5 3,15,3 3,15,4 3,15,5 3,16,3 3,16,4 3,16,5 3,17,3 3,17,4 3,17,5 3,18,3 3,18,4 3,18,5 4,12,2 4,12,3 4,12,4 4,12,5 4,13,2 4,13,3 4,13,4 4,13,5 4,14,2 4,14,3 4,14,4 4,14,5 4,15,2 4,15,3 4,15,4 4,15,5 4,16,2 4,16,3 4,16,4 4,16,5 4,17,2 4,17,3 4,17,4 4,17,5 4,18,2 4,18,3 4,18,4 4,18,5 5,12,2 5,12,3 5,12,4 5,12,5 5,13,2 5,13,3 5,13,4 5,13,5 5,14,2 5,14,3 5,14,4 5,14,5 5,15,2 5,15,3 5,15,4 5,15,5 5,16,2 5,16,3 5,16,4 5,16,5 5,17,2 5,17,3 5,17,4 5,17,5 5,18,2 5,18,3 5,18,4 5,18,5 6,10,2 6,10,3 6,10,4 6,10,5 6,11,2 6,11,3 6,11,4 6,11,5 6,12,2 6,12,3 6,12,4 6,12,5 6,13,2 6,13,3 6,13,4 6,13,5 6,14,2 6,14,3 6,14,4 6,14,5 6,15,2 6,15,3 6,15,4 6,15,5 6,16,2 6,16,3 6,16,4 6,16,5 6,17,2 6,17,3 6,17,4 6,17,5 6,18,2 6,18,3 6,18,4 6,18,5 7,10,1 7,10,2 7,10,3 7,10,4 7,10,5 7,11,1 7,11,2 7,11,3 7,11,4 7,11,5 7,12,1 7,12,2 7,12,3 7,12,4 7,12,5 7,13,1 7,13,2 7,13,3 7,13,4 7,13,5 7,14,1 7,14,2 7,14,3 7,14,4 7,14,5 7,15,1 7,15,2 7,15,3 7,15,4 7,15,5 7,16,1 7,16,2 7,16,3 7,16,4 7,16,5 7,17,1 7,17,2 7,17,3 7,17,4 7,17,5 7,18,1 7,18,2 7,18,3 7,18,4 7,18,5

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  • Create a linear trend line in Excel graphs with logarithmic scale

    - by Redsoft7
    I I have an Excel scatter chart with x and y values. I set the logarithmic scale in x-axis and y-axis. When I add a linear trend line to the graph, the line is not linear but appears like a curve. How can I make a linear trend line on a logarithmic-scaled chart? Sample data: x: 18449 22829 25395 36869 101419 125498 208144 2001508 14359478 17301785 y: 269,09 273,89 239,50 239,50 175,13 176,73 151,94 135,15 131,55 121,55

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  • Looking for something to monitor an Internet Shared Connection in Windows XP

    - by thenewbie
    If someone knows a software with these features: Works from the tray area Very lightweight Works also in Windows XP (preferably workstation, nothing serverish required) Can show a bandwidth usage graph, where I can easily see each PC's usage I can inspect a computer's connections, find out the ports and applications that are using them (eg, all bandwidth is consumed by PC #3, that's running uTorrent.exe from port 33003) ...I'd happily check it out. I'm only sharing my connection with (at most) 4 computers, I'd prefer not having to add hardware or reinstall my system. Thanks in advance!

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  • Parsing adobe Kuler RSS feed

    - by dezkev
    I have been trying to parse the below XML file (kuler rss feed). I have read the various posts on this site but am unable to piece them together. I specifically want to extract the child(or siblings) nodes of the element <kuler:themeItem>. However I am getting an exception : Namespace Manager or XsltContext needed. This query has a prefix, variable, or user-defined function. Pl help : C# 3.0 net framework 3.5 RSS feed snippet: <?xml version="1.0" encoding="UTF-8" ?> - <rss xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:kuler="http://kuler.adobe.com/kuler/API/rss/" xmlns:rss="http://blogs.law.harvard.edu/tech/rss" version="2.0"> - <channel> <title>kuler recent themes</title> <link>http://kuler.adobe.com/</link> <description>most recent themes published on kuler (1 to 20 of 332518)</description> <language>en-us</language> <pubDate>Wed, 07 Apr 2010 08:41:31 PST</pubDate> <lastBuildDate>Wed, 07 Apr 2010 08:41:31 PST</lastBuildDate> <docs>http://blogs.law.harvard.edu/tech/rss</docs> <generator>Kuler Services</generator> <managingEditor>[email protected]</managingEditor> <webMaster>[email protected]</webMaster> <recordCount>332518</recordCount> <startIndex>0</startIndex> <itemsPerPage>20</itemsPerPage> - <item> <title>Theme Title: Muted Graph</title> <link>http://kuler.adobe.com/index.cfm#themeID/856075</link> <guid>http://kuler.adobe.com/index.cfm#themeID/856075</guid> - <enclosure xmlns="http://www.solitude.dk/syndication/enclosures/"> <title>Muted Graph</title> - <link length="1" type="image/png"> <url>http://kuler-api.adobe.com/kuler/themeImages/theme_856075.png</url> </link> </enclosure> <description><img src="http://kuler-api.adobe.com/kuler/themeImages/theme_856075.png" /><br /> Artist: tischt<br /> ThemeID: 856075<br /> Posted: 04/07/2010<br /> Hex: F1E9B2, 3D3606, 2A3231, 4A0A07, 424431</description> - <kuler:themeItem> <kuler:themeID>856075</kuler:themeID> <kuler:themeTitle>Muted Graph</kuler:themeTitle> <kuler:themeImage>http://kuler-api.adobe.com/kuler/themeImages/theme_856075.png</kuler:themeImage> - <kuler:themeAuthor> <kuler:authorID>216099</kuler:authorID> <kuler:authorLabel>tischt</kuler:authorLabel> </kuler:themeAuthor> <kuler:themeTags /> <kuler:themeRating>0</kuler:themeRating> <kuler:themeDownloadCount>0</kuler:themeDownloadCount> <kuler:themeCreatedAt>20100407</kuler:themeCreatedAt> <kuler:themeEditedAt>20100407</kuler:themeEditedAt> - <kuler:themeSwatches> - <kuler:swatch> <kuler:swatchHexColor>F1E9B2</kuler:swatchHexColor> <kuler:swatchColorMode>rgb</kuler:swatchColorMode> <kuler:swatchChannel1>0.945098</kuler:swatchChannel1> <kuler:swatchChannel2>0.913725</kuler:swatchChannel2> <kuler:swatchChannel3>0.698039</kuler:swatchChannel3> <kuler:swatchChannel4>0.0</kuler:swatchChannel4> <kuler:swatchIndex>0</kuler:swatchIndex> </kuler:swatch> My Code so far: static void Main(string[] args) { const string feedUrl = "http://kuler-api.adobe.com/rss/get.cfm?listtype=recent&key=xxxx"; var doc = new XmlDocument(); var request = WebRequest.Create(feedUrl) as HttpWebRequest; using (var response = request.GetResponse() as HttpWebResponse) { var reader = new StreamReader(response.GetResponseStream()); doc.Load(reader); } XmlNodeList rsslist = doc.SelectNodes("//rss/channel/item/kuler:themeItem"); for (int i = 0; i < rsslist.Count; i++) { XmlNode rssdetail = rsslist.Item(i).SelectSingleNode("kuler:themeTitle"); string title = rssdetail.InnerText; Console.WriteLine(title); } } }

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  • Excel 2007: plot data points not on an axis/ force linear x-incrementation without altering integrity of non-linear data

    - by Ennapode
    In Excel, how does one go about plotting points that don't have an x component that is an x-axis label? For example, in my graph, the x-components are derived from the cosine function and aren't linear, but Excel is displaying them as if .0016 to .0062 to .0135 is an equal incrementation. How would I change this so that the x-axis has an even incrementation without altering the integrity of the points themselves? In other words, how do I plot a point with an x component independent from the x-axis label?

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  • Data Profiling without SSIS

    Strangely enough for a predominantly SSIS blog, this post is all about how to perform data profiling without using SSIS. Whilst the Data Profiling Task is a worthy addition, there are a couple of limitations I’ve encountered of late. The first is that it requires SQL Server 2008, and not everyone is there yet. The second is that it can only target SQL Server 2005 and above. What about older systems, which are the ones that we probably need to investigate the most, or other vendor databases such as Oracle? With these limitations in mind I did some searching to find a quick and easy alternative to help me perform some data profiling for a project I was working on recently. I only had SQL Server 2005 available, and anyway most of my target source systems were Oracle, and of course I had short timescales. I looked at several options. Some never got beyond the download stage, they failed to install or just did not run, and others provided less than I could have produced myself by spending 2 minutes writing some basic SQL queries. In the end I settled on an open source product called DataCleaner. To quote from their website: DataCleaner is an Open Source application for profiling, validating and comparing data. These activities help you administer and monitor your data quality in order to ensure that your data is useful and applicable to your business situation. DataCleaner is the free alternative to software for master data management (MDM) methodologies, data warehousing (DW) projects, statistical research, preparation for extract-transform-load (ETL) activities and more. DataCleaner is developed in Java and licensed under LGPL. As quoted above it claims to support profiling, validating and comparing data, but I didn’t really get past the profiling functions, so won’t comment on the other two. The profiling whilst not prefect certainly saved some time compared to the limited alternatives. The ability to profile heterogeneous data sources is a big advantage over the SSIS option, and I found it overall quite easy to use and performance was good. I could see it struggling at times, but actually for what it does I was impressed. It had some data type niggles with Oracle, and some metrics seem a little strange, although thankfully they were easy to augment with some SQL queries to ensure a consistent picture. The report export options didn’t do it for me, but copy and paste with a bit of Excel magic was sufficient. One initial point for me personally is that I have had limited exposure to things of the Java persuasion and whilst I normally get by fine, sometimes the simplest things can throw me. For example installing a JDBC driver, why do I have to copy files to make it all work, has nobody ever heard of an MSI? In case there are other people out there like me who have become totally indoctrinated with the Microsoft software paradigm, I’ve written a quick start guide that details every step required. Steps 1- 5 are the key ones, the rest is really an excuse for some screenshots to show you the tool. Quick Start Guide Step 1  - Download Data Cleaner. The Microsoft Windows zipped exe option, and I chose the latest stable build, currently DataCleaner 1.5.3 (final). Extract the files to a suitable location. Step 2 - Download Java. If you try and run datacleaner.exe without Java it will warn you, and then open your default browser and take you to the Java download site. Follow the installation instructions from there, normally just click Download Java a couple of times and you’re done. Step 3 - Download Microsoft SQL Server JDBC Driver. You may have SQL Server installed, but you won’t have a JDBC driver. Version 3.0 is the latest as of April 2010. There is no real installer, we are in the Java world here, but run the exe you downloaded to extract the files. The default Unzip to folder is not much help, so try a fully qualified path such as C:\Program Files\Microsoft SQL Server JDBC Driver 3.0\ to ensure you can find the files afterwards. Step 4 - If you wish to use Windows Authentication to connect to your SQL Server then first we need to copy a file so that Data Cleaner can find it. Browse to the JDBC extract location from Step 3 and drill down to the file sqljdbc_auth.dll. You will have to choose the correct directory for your processor architecture. e.g. C:\Program Files\Microsoft SQL Server JDBC Driver 3.0\sqljdbc_3.0\enu\auth\x86\sqljdbc_auth.dll. Now copy this file to the Data Cleaner extract folder you chose in Step 1. An alternative method is to edit datacleaner.cmd in the data cleaner extract folder as detailed in this data cleaner wiki topic, but I find copying the file simpler. Step 5 – Now lets run Data Cleaner, just run datacleaner.exe from the extract folder you chose in Step 1. Step 6 – Complete or skip the registration screen, and ignore the task window for now. In the main window click settings. Step 7 – In the Settings dialog, select the Database drivers tab, then click Register database driver and select the Local JAR file option. Step 8 – Browse to the JDBC driver extract location from Step 3 and drill down to select sqljdbc4.jar. e.g. C:\Program Files\Microsoft SQL Server JDBC Driver 3.0\sqljdbc_3.0\enu\sqljdbc4.jar Step 9 – Select the Database driver class as com.microsoft.sqlserver.jdbc.SQLServerDriver, and then click the Test and Save database driver button. Step 10 - You should be back at the Settings dialog with a the list of drivers that includes SQL Server. Just click Save Settings to persist all your hard work. Step 11 – Now we can start to profile some data. In the main Data Cleaner window click New Task, and then Profile from the task window. Step 12 – In the Profile window click Open Database Step 13 – Now choose the SQL Server connection string option. Selecting a connection string gives us a template like jdbc:sqlserver://<hostname>:1433;databaseName=<database>, but obviously it requires some details to be entered for example  jdbc:sqlserver://localhost:1433;databaseName=SQLBits. This will connect to the database called SQLBits on my local machine. The port may also have to be changed if using such as when you have a multiple instances of SQL Server running. If using SQL Server Authentication enter a username and password as required and then click Connect to database. You can use Window Authentication, just add integratedSecurity=true to the end of your connection string. e.g jdbc:sqlserver://localhost:1433;databaseName=SQLBits;integratedSecurity=true.  If you didn’t complete Step 4 above you will need to do so now and restart Data Cleaner before it will work. Manually setting the connection string is fine, but creating a named connection makes more sense if you will be spending any length of time profiling a specific database. As highlighted in the left-hand screen-shot, at the bottom of the dialog it includes partial instructions on how to create named connections. In the folder shown C:\Users\<Username>\.datacleaner\1.5.3, open the datacleaner-config.xml file in your editor of choice add your own details. You’ll see a sample connection in the file already, just add yours following the same pattern. e.g. <!-- Darren's Named Connections --> <bean class="dk.eobjects.datacleaner.gui.model.NamedConnection"> <property name="name" value="SQLBits Local Connection" /> <property name="driverClass" value="com.microsoft.sqlserver.jdbc.SQLServerDriver" /> <property name="connectionString" value="jdbc:sqlserver://localhost:1433;databaseName=SQLBits;integratedSecurity=true" /> <property name="tableTypes"> <list> <value>TABLE</value> <value>VIEW</value> </list> </property> </bean> Step 14 – Once back at the Profile window, you should now see your schemas, tables and/or views listed down the left hand side. Browse this tree and double-click a table to select it for profiling. You can then click Add profile, and choose some profiling options, before finally clicking Run profiling. You can see below a sample output for three of the most common profiles, click the image for full size.   I hope this has given you a taster for DataCleaner, and should help you get up and running pretty quickly.

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  • Demystifying Silverlight Dependency Properties

    - by dwahlin
    I have the opportunity to teach a lot of people about Silverlight (amongst other technologies) and one of the topics that definitely confuses people initially is the concept of dependency properties. I confess that when I first heard about them my initial thought was “Why do we need a specialized type of property?” While you can certainly use standard CLR properties in Silverlight applications, Silverlight relies heavily on dependency properties for just about everything it does behind the scenes. In fact, dependency properties are an essential part of the data binding, template, style and animation functionality available in Silverlight. They simply back standard CLR properties. In this post I wanted to put together a (hopefully) simple explanation of dependency properties and why you should care about them if you’re currently working with Silverlight or looking to move to it.   What are Dependency Properties? XAML provides a great way to define layout controls, user input controls, shapes, colors and data binding expressions in a declarative manner. There’s a lot that goes on behind the scenes in order to make XAML work and an important part of that magic is the use of dependency properties. If you want to bind data to a property, style it, animate it or transform it in XAML then the property involved has to be a dependency property to work properly. If you’ve ever positioned a control in a Canvas using Canvas.Left or placed a control in a specific Grid row using Grid.Row then you’ve used an attached property which is a specialized type of dependency property. Dependency properties play a key role in XAML and the overall Silverlight framework. Any property that you bind, style, template, animate or transform must be a dependency property in Silverlight applications. You can programmatically bind values to controls and work with standard CLR properties, but if you want to use the built-in binding expressions available in XAML (one of my favorite features) or the Binding class available through code then dependency properties are a necessity. Dependency properties aren’t needed in every situation, but if you want to customize your application very much you’ll eventually end up needing them. For example, if you create a custom user control and want to expose a property that consumers can use to change the background color, you have to define it as a dependency property if you want bindings, styles and other features to be available for use. Now that the overall purpose of dependency properties has been discussed let’s take a look at how you can create them. Creating Dependency Properties When .NET first came out you had to write backing fields for each property that you defined as shown next: Brush _ScheduleBackground; public Brush ScheduleBackground { get { return _ScheduleBackground; } set { _ScheduleBackground = value; } } Although .NET 2.0 added auto-implemented properties (for example: public Brush ScheduleBackground { get; set; }) where the compiler would automatically generate the backing field used by get and set blocks, the concept is still the same as shown in the above code; a property acts as a wrapper around a field. Silverlight dependency properties replace the _ScheduleBackground field shown in the previous code and act as the backing store for a standard CLR property. The following code shows an example of defining a dependency property named ScheduleBackgroundProperty: public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), null);   Looking through the code the first thing that may stand out is that the definition for ScheduleBackgroundProperty is marked as static and readonly and that the property appears to be of type DependencyProperty. This is a standard pattern that you’ll use when working with dependency properties. You’ll also notice that the property explicitly adds the word “Property” to the name which is another standard you’ll see followed. In addition to defining the property, the code also makes a call to the static DependencyProperty.Register method and passes the name of the property to register (ScheduleBackground in this case) as a string. The type of the property, the type of the class that owns the property and a null value (more on the null value later) are also passed. In this example a class named Scheduler acts as the owner. The code handles registering the property as a dependency property with the call to Register(), but there’s a little more work that has to be done to allow a value to be assigned to and retrieved from the dependency property. The following code shows the complete code that you’ll typically use when creating a dependency property. You can find code snippets that greatly simplify the process of creating dependency properties out on the web. The MVVM Light download available from http://mvvmlight.codeplex.com comes with built-in dependency properties snippets as well. public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), null); public Brush ScheduleBackground { get { return (Brush)GetValue(ScheduleBackgroundProperty); } set { SetValue(ScheduleBackgroundProperty, value); } } The standard CLR property code shown above should look familiar since it simply wraps the dependency property. However, you’ll notice that the get and set blocks call GetValue and SetValue methods respectively to perform the appropriate operation on the dependency property. GetValue and SetValue are members of the DependencyObject class which is another key component of the Silverlight framework. Silverlight controls and classes (TextBox, UserControl, CompositeTransform, DataGrid, etc.) ultimately derive from DependencyObject in their inheritance hierarchy so that they can support dependency properties. Dependency properties defined in Silverlight controls and other classes tend to follow the pattern of registering the property by calling Register() and then wrapping the dependency property in a standard CLR property (as shown above). They have a standard property that wraps a registered dependency property and allows a value to be assigned and retrieved. If you need to expose a new property on a custom control that supports data binding expressions in XAML then you’ll follow this same pattern. Dependency properties are extremely useful once you understand why they’re needed and how they’re defined. Detecting Changes and Setting Defaults When working with dependency properties there will be times when you want to assign a default value or detect when a property changes so that you can keep the user interface in-sync with the property value. Silverlight’s DependencyProperty.Register() method provides a fourth parameter that accepts a PropertyMetadata object instance. PropertyMetadata can be used to hook a callback method to a dependency property. The callback method is called when the property value changes. PropertyMetadata can also be used to assign a default value to the dependency property. By assigning a value of null for the final parameter passed to Register() you’re telling the property that you don’t care about any changes and don’t have a default value to apply. Here are the different constructor overloads available on the PropertyMetadata class: PropertyMetadata Constructor Overload Description PropertyMetadata(Object) Used to assign a default value to a dependency property. PropertyMetadata(PropertyChangedCallback) Used to assign a property changed callback method. PropertyMetadata(Object, PropertyChangedCalback) Used to assign a default property value and a property changed callback.   There are many situations where you need to know when a dependency property changes or where you want to apply a default. Performing either task is easily accomplished by creating a new instance of the PropertyMetadata class and passing the appropriate values to its constructor. The following code shows an enhanced version of the initial dependency property code shown earlier that demonstrates these concepts: public Brush ScheduleBackground { get { return (Brush)GetValue(ScheduleBackgroundProperty); } set { SetValue(ScheduleBackgroundProperty, value); } } public static readonly DependencyProperty ScheduleBackgroundProperty = DependencyProperty.Register("ScheduleBackground", typeof(Brush), typeof(Scheduler), new PropertyMetadata(new SolidColorBrush(Colors.LightGray), ScheduleBackgroundChanged)); private static void ScheduleBackgroundChanged(DependencyObject d, DependencyPropertyChangedEventArgs e) { var scheduler = d as Scheduler; scheduler.Background = e.NewValue as Brush; } The code wires ScheduleBackgroundProperty to a property change callback method named ScheduleBackgroundChanged. What’s interesting is that this callback method is static (as is the dependency property) so it gets passed the instance of the object that owns the property that has changed (otherwise we wouldn’t be able to get to the object instance). In this example the dependency object is cast to a Scheduler object and its Background property is assigned to the new value of the dependency property. The code also handles assigning a default value of LightGray to the dependency property by creating a new instance of a SolidColorBrush. To Sum Up In this post you’ve seen the role of dependency properties and how they can be defined in code. They play a big role in XAML and the overall Silverlight framework. You can think of dependency properties as being replacements for fields that you’d normally use with standard CLR properties. In addition to a discussion on how dependency properties are created, you also saw how to use the PropertyMetadata class to define default dependency property values and hook a dependency property to a callback method. The most important thing to understand with dependency properties (especially if you’re new to Silverlight) is that they’re needed if you want a property to support data binding, animations, transformations and styles properly. Any time you create a property on a custom control or user control that has these types of requirements you’ll want to pick a dependency property over of a standard CLR property with a backing field. There’s more that can be covered with dependency properties including a related property called an attached property….more to come.

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  • Metro: Promises

    - by Stephen.Walther
    The goal of this blog entry is to describe the Promise class in the WinJS library. You can use promises whenever you need to perform an asynchronous operation such as retrieving data from a remote website or a file from the file system. Promises are used extensively in the WinJS library. Asynchronous Programming Some code executes immediately, some code requires time to complete or might never complete at all. For example, retrieving the value of a local variable is an immediate operation. Retrieving data from a remote website takes longer or might not complete at all. When an operation might take a long time to complete, you should write your code so that it executes asynchronously. Instead of waiting for an operation to complete, you should start the operation and then do something else until you receive a signal that the operation is complete. An analogy. Some telephone customer service lines require you to wait on hold – listening to really bad music – until a customer service representative is available. This is synchronous programming and very wasteful of your time. Some newer customer service lines enable you to enter your telephone number so the customer service representative can call you back when a customer representative becomes available. This approach is much less wasteful of your time because you can do useful things while waiting for the callback. There are several patterns that you can use to write code which executes asynchronously. The most popular pattern in JavaScript is the callback pattern. When you call a function which might take a long time to return a result, you pass a callback function to the function. For example, the following code (which uses jQuery) includes a function named getFlickrPhotos which returns photos from the Flickr website which match a set of tags (such as “dog” and “funny”): function getFlickrPhotos(tags, callback) { $.getJSON( "http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?", { tags: tags, tagmode: "all", format: "json" }, function (data) { if (callback) { callback(data.items); } } ); } getFlickrPhotos("funny, dogs", function(data) { $.each(data, function(index, item) { console.log(item); }); }); The getFlickr() function includes a callback parameter. When you call the getFlickr() function, you pass a function to the callback parameter which gets executed when the getFlicker() function finishes retrieving the list of photos from the Flickr web service. In the code above, the callback function simply iterates through the results and writes each result to the console. Using callbacks is a natural way to perform asynchronous programming with JavaScript. Instead of waiting for an operation to complete, sitting there and listening to really bad music, you can get a callback when the operation is complete. Using Promises The CommonJS website defines a promise like this (http://wiki.commonjs.org/wiki/Promises): “Promises provide a well-defined interface for interacting with an object that represents the result of an action that is performed asynchronously, and may or may not be finished at any given point in time. By utilizing a standard interface, different components can return promises for asynchronous actions and consumers can utilize the promises in a predictable manner.” A promise provides a standard pattern for specifying callbacks. In the WinJS library, when you create a promise, you can specify three callbacks: a complete callback, a failure callback, and a progress callback. Promises are used extensively in the WinJS library. The methods in the animation library, the control library, and the binding library all use promises. For example, the xhr() method included in the WinJS base library returns a promise. The xhr() method wraps calls to the standard XmlHttpRequest object in a promise. The following code illustrates how you can use the xhr() method to perform an Ajax request which retrieves a file named Photos.txt: var options = { url: "/data/photos.txt" }; WinJS.xhr(options).then( function (xmlHttpRequest) { console.log("success"); var data = JSON.parse(xmlHttpRequest.responseText); console.log(data); }, function(xmlHttpRequest) { console.log("fail"); }, function(xmlHttpRequest) { console.log("progress"); } ) The WinJS.xhr() method returns a promise. The Promise class includes a then() method which accepts three callback functions: a complete callback, an error callback, and a progress callback: Promise.then(completeCallback, errorCallback, progressCallback) In the code above, three anonymous functions are passed to the then() method. The three callbacks simply write a message to the JavaScript Console. The complete callback also dumps all of the data retrieved from the photos.txt file. Creating Promises You can create your own promises by creating a new instance of the Promise class. The constructor for the Promise class requires a function which accepts three parameters: a complete, error, and progress function parameter. For example, the code below illustrates how you can create a method named wait10Seconds() which returns a promise. The progress function is called every second and the complete function is not called until 10 seconds have passed: (function () { "use strict"; var app = WinJS.Application; function wait10Seconds() { return new WinJS.Promise(function (complete, error, progress) { var seconds = 0; var intervalId = window.setInterval(function () { seconds++; progress(seconds); if (seconds > 9) { window.clearInterval(intervalId); complete(); } }, 1000); }); } app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { wait10Seconds().then( function () { console.log("complete") }, function () { console.log("error") }, function (seconds) { console.log("progress:" + seconds) } ); } } app.start(); })(); All of the work happens in the constructor function for the promise. The window.setInterval() method is used to execute code every second. Every second, the progress() callback method is called. If more than 10 seconds have passed then the complete() callback method is called and the clearInterval() method is called. When you execute the code above, you can see the output in the Visual Studio JavaScript Console. Creating a Timeout Promise In the previous section, we created a custom Promise which uses the window.setInterval() method to complete the promise after 10 seconds. We really did not need to create a custom promise because the Promise class already includes a static method for returning promises which complete after a certain interval. The code below illustrates how you can use the timeout() method. The timeout() method returns a promise which completes after a certain number of milliseconds. WinJS.Promise.timeout(3000).then( function(){console.log("complete")}, function(){console.log("error")}, function(){console.log("progress")} ); In the code above, the Promise completes after 3 seconds (3000 milliseconds). The Promise returned by the timeout() method does not support progress events. Therefore, the only message written to the console is the message “complete” after 10 seconds. Canceling Promises Some promises, but not all, support cancellation. When you cancel a promise, the promise’s error callback is executed. For example, the following code uses the WinJS.xhr() method to perform an Ajax request. However, immediately after the Ajax request is made, the request is cancelled. // Specify Ajax request options var options = { url: "/data/photos.txt" }; // Make the Ajax request var request = WinJS.xhr(options).then( function (xmlHttpRequest) { console.log("success"); }, function (xmlHttpRequest) { console.log("fail"); }, function (xmlHttpRequest) { console.log("progress"); } ); // Cancel the Ajax request request.cancel(); When you run the code above, the message “fail” is written to the Visual Studio JavaScript Console. Composing Promises You can build promises out of other promises. In other words, you can compose promises. There are two static methods of the Promise class which you can use to compose promises: the join() method and the any() method. When you join promises, a promise is complete when all of the joined promises are complete. When you use the any() method, a promise is complete when any of the promises complete. The following code illustrates how to use the join() method. A new promise is created out of two timeout promises. The new promise does not complete until both of the timeout promises complete: WinJS.Promise.join([WinJS.Promise.timeout(1000), WinJS.Promise.timeout(5000)]) .then(function () { console.log("complete"); }); The message “complete” will not be written to the JavaScript Console until both promises passed to the join() method completes. The message won’t be written for 5 seconds (5,000 milliseconds). The any() method completes when any promise passed to the any() method completes: WinJS.Promise.any([WinJS.Promise.timeout(1000), WinJS.Promise.timeout(5000)]) .then(function () { console.log("complete"); }); The code above writes the message “complete” to the JavaScript Console after 1 second (1,000 milliseconds). The message is written to the JavaScript console immediately after the first promise completes and before the second promise completes. Summary The goal of this blog entry was to describe WinJS promises. First, we discussed how promises enable you to easily write code which performs asynchronous actions. You learned how to use a promise when performing an Ajax request. Next, we discussed how you can create your own promises. You learned how to create a new promise by creating a constructor function with complete, error, and progress parameters. Finally, you learned about several advanced methods of promises. You learned how to use the timeout() method to create promises which complete after an interval of time. You also learned how to cancel promises and compose promises from other promises.

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  • Metro: Understanding Observables

    - by Stephen.Walther
    The goal of this blog entry is to describe how the Observer Pattern is implemented in the WinJS library. You learn how to create observable objects which trigger notifications automatically when their properties are changed. Observables enable you to keep your user interface and your application data in sync. For example, by taking advantage of observables, you can update your user interface automatically whenever the properties of a product change. Observables are the foundation of declarative binding in the WinJS library. The WinJS library is not the first JavaScript library to include support for observables. For example, both the KnockoutJS library and the Microsoft Ajax Library (now part of the Ajax Control Toolkit) support observables. Creating an Observable Imagine that I have created a product object like this: var product = { name: "Milk", description: "Something to drink", price: 12.33 }; Nothing very exciting about this product. It has three properties named name, description, and price. Now, imagine that I want to be notified automatically whenever any of these properties are changed. In that case, I can create an observable product from my product object like this: var observableProduct = WinJS.Binding.as(product); This line of code creates a new JavaScript object named observableProduct from the existing JavaScript object named product. This new object also has a name, description, and price property. However, unlike the properties of the original product object, the properties of the observable product object trigger notifications when the properties are changed. Each of the properties of the new observable product object has been changed into accessor properties which have both a getter and a setter. For example, the observable product price property looks something like this: price: { get: function () { return this.getProperty(“price”); } set: function (value) { this.setProperty(“price”, value); } } When you read the price property then the getProperty() method is called and when you set the price property then the setProperty() method is called. The getProperty() and setProperty() methods are methods of the observable product object. The observable product object supports the following methods and properties: · addProperty(name, value) – Adds a new property to an observable and notifies any listeners. · backingData – An object which represents the value of each property. · bind(name, action) – Enables you to execute a function when a property changes. · getProperty(name) – Returns the value of a property using the string name of the property. · notify(name, newValue, oldValue) – A private method which executes each function in the _listeners array. · removeProperty(name) – Removes a property and notifies any listeners. · setProperty(name, value) – Updates a property and notifies any listeners. · unbind(name, action) – Enables you to stop executing a function in response to a property change. · updateProperty(name, value) – Updates a property and notifies any listeners. So when you create an observable, you get a new object with the same properties as an existing object. However, when you modify the properties of an observable object, then you can notify any listeners of the observable that the value of a particular property has changed automatically. Imagine that you change the value of the price property like this: observableProduct.price = 2.99; In that case, the following sequence of events is triggered: 1. The price setter calls the setProperty(“price”, 2.99) method 2. The setProperty() method updates the value of the backingData.price property and calls the notify() method 3. The notify() method executes each function in the collection of listeners associated with the price property Creating Observable Listeners If you want to be notified when a property of an observable object is changed, then you need to register a listener. You register a listener by using the bind() method like this: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 2.99; } }; app.start(); })(); In the code above, the bind() method is used to associate the price property with a function. When the price property is changed, the function logs the new value of the price property to the Visual Studio JavaScript console. The price property is associated with the function using the following line of code: // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); Coalescing Notifications If you make multiple changes to a property – one change immediately following another – then separate notifications won’t be sent. Instead, any listeners are notified only once. The notifications are coalesced into a single notification. For example, in the following code, the product price property is updated three times. However, only one message is written to the JavaScript console. Only the last value assigned to the price property is written to the JavaScript Console window: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 3.99; observableProduct.price = 2.99; observableProduct.price = 1.99; Only the last value assigned to price, the value 1.99, appears in the console: If there is a time delay between changes to a property then changes result in different notifications. For example, the following code updates the price property every second: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Add 1 to price every second window.setInterval(function () { observableProduct.price += 1; }, 1000); In this case, separate notification messages are logged to the JavaScript Console window: If you need to prevent multiple notifications from being coalesced into one then you can take advantage of promises. I discussed WinJS promises in a previous blog entry: http://stephenwalther.com/blog/archive/2012/02/22/windows-web-applications-promises.aspx Because the updateProperty() method returns a promise, you can create different notifications for each change in a property by using the following code: // Change the price observableProduct.updateProperty("price", 3.99) .then(function () { observableProduct.updateProperty("price", 2.99) .then(function () { observableProduct.updateProperty("price", 1.99); }); }); In this case, even though the price is immediately changed from 3.99 to 2.99 to 1.99, separate notifications for each new value of the price property are sent. Bypassing Notifications Normally, if a property of an observable object has listeners and you change the property then the listeners are notified. However, there are certain situations in which you might want to bypass notification. In other words, you might need to change a property value silently without triggering any functions registered for notification. If you want to change a property without triggering notifications then you should change the property by using the backingData property. The following code illustrates how you can change the price property silently: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price silently observableProduct.backingData.price = 5.99; console.log(observableProduct.price); // Writes 5.99 The price is changed to the value 5.99 by changing the value of backingData.price. Because the observableProduct.price property is not set directly, any listeners associated with the price property are not notified. When you change the value of a property by using the backingData property, the change in the property happens synchronously. However, when you change the value of an observable property directly, the change is always made asynchronously. Summary The goal of this blog entry was to describe observables. In particular, we discussed how to create observables from existing JavaScript objects and bind functions to observable properties. You also learned how notifications are coalesced (and ways to prevent this coalescing). Finally, we discussed how you can use the backingData property to update an observable property without triggering notifications. In the next blog entry, we’ll see how observables are used with declarative binding to display the values of properties in an HTML document.

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